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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

(Mark One)

For the fiscal year ended December 31, 2022

OR

Commission File Number 001-39460

KYMERA THERAPEUTICS, INC.

(Exact name of Registrant as specified in its Charter)

Registrant’s telephone number, including area code: (857) 285-5300

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☒ NO ☐

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. YES ☐ No ☒

Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ NO ☐

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). Yes ☒ NO ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements. ☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executiveofficers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES ☐ No ☒

The aggregate market value of the registrant’s common stock, $0.0001 par value per share, held by non-affiliates of the registrant, based on the last sale price of the Common Stock at the close of business on June 30, 2022, was $792.0 million. Shares of common stock held by each executive officer and director and by each other person who may be deemed to be an affiliate of the registrant have been excluded from this computation. The determination of affiliate status for this purpose is not necessarily a conclusive determination for other purposes.

The number of shares of Registrant’s Common Stock outstanding as of February 17, 2023 was 55,183,644.

DOCUMENTS INCORPORATED BY REFERENCE

Table of Contents

i

SUMMARY OF THE MATERIAL AND OTHER RISKS ASSOCIATED WITH OUR BUSINESS

ii

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K, or Annual Report, contains forward-looking statements which are made pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements other than statements of historical facts contained in this Annual Report are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as “may”, “will”, “should”, “expects”, “intends”, “plans”, “anticipates”, “believes”, “estimates”, “predicts”, “potential”, “continue” or the negative of these terms or other comparable terminology. These statements are not guarantees of future results or performance and involve substantial risks and uncertainties. Forward-looking statements in this Annual Report include, but are not limited to, express or implied statements about:

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Any forward-looking statements in this Annual Report reflect our current views with respect to future events and with respect to our future financial performance, and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by these forward-looking statements. Factors that may cause actual results to differ materially from current expectations include, among other things, those described under Part I, Item 1A, “Risk Factors” and elsewhere in this Annual Report. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Except as required by law, we assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future.

All of our forward-looking statements are as of the date of this Annual Report only. In each case, actual results may differ materially from such forward-looking information. We can give no assurance that such expectations or forward-looking statements will prove to be correct. An occurrence of or any material adverse change in one or more of the risk factors or risks and uncertainties referred to in this Annual Report or included in our other public disclosures or our other periodic reports or other documents or filings filed with or furnished to the Securities and Exchange Commission, or the SEC, could materially and adversely affect our business, prospects, financial condition and results of operations. Except as required by law, we do not undertake or plan to update or revise any such forward-looking statements to reflect actual results, changes in plans, assumptions, estimates or projections or other circumstances affecting such forward-looking statements occurring after the date of this Annual Report, even if such results, changes or circumstances make it clear that any forward-looking information will not be realized. Any public statements or disclosures by us following this Annual Report that modify or impact any of the forward-looking statements contained in this Annual Report will be deemed to modify or supersede such statements in this Annual Report.

We may from time to time provide estimates, projections and other information concerning our industry, the general business environment, and the markets for certain diseases, including estimates regarding the potential size of those markets and the estimated incidence and prevalence of certain medical conditions. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties, and actual events, circumstances or numbers, including actual disease prevalence rates and market size, may differ materially from the information reflected in this Annual Report. Unless otherwise expressly stated, we obtained this industry, business information, market data, prevalence information and other data from reports, research surveys, studies and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data, and similar sources, in some cases applying our own assumptions and analysis that may, in the future, prove not to have been accurate.

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PART I

Item 1. Business.

We are a biopharmaceutical company focused on discovering and developing novel small molecule therapeutics that selectively degrade disease-causing proteins by harnessing the body’s own natural protein degradation system. Our proprietary targeted protein degradation, or TPD, platform, which we refer to as Pegasus™, enables us to discover highly selective small molecule protein degraders with activity against disease-causing proteins throughout the body. We believe that our small molecule protein degraders have unique advantages over existing therapies and allow us to address a large portion of the human genome that was previously intractable with traditional modalities. We focus on biological pathways that have been clinically validated but where key biological nodes/proteins have not been drugged or have been inadequately drugged. To date, we have utilized our Pegasus™ platform to design novel protein degraders focused in the areas of immunology-inflammation and oncology, and we continue to apply our platform’s capabilities to additional therapeutic areas. We have a mission to drug all target classes in human cells using TPD.

Our programs exemplify our focus on addressing high impact targets that have been elusive to conventional modalities and that drive the pathogenesis of multiple serious diseases with significant unmet medical needs. Our current clinical stage programs are IRAK4, IRAKIMiD, and STAT3, which each address high impact targets within the interleukin-1 receptor/toll-like receptor, or IL-1R/TLR, and janus kinase/signal transducers and activators of transcription, or JAK/STAT, pathways, providing the opportunity to treat a broad range of immune-inflammatory diseases, hematologic malignancies, and solid tumors. Our fourth clinical program, MDM2, targets both solid and hematologic malignancies.

With respect to our IRAK4 program, we are collaborating with Sanofi S.A, or Sanofi, on the development of drug candidates targeting IRAK4 outside the oncology and immuno-oncology fields. We are developing KT-474, a highly active and selective, orally bioavailable IRAK4 degrader, for the treatment of IL-1R/TLR-driven immunology-inflammation conditions and diseases with high unmet medical need, including hidradenitis suppurativa, or HS, an inflammatory skin disease, as well as atopic dermatitis, or AD, and potentially other indications. We have completed our Phase 1 trial of KT-474, which included a single ascending dose, or SAD, portion, a multiple ascending dose, or MAD, portion and a single dose, food-effect cohort to establish the dose for the patient cohort, or Part C, in patients with HS and AD. In December 2022, Sanofi notified us of its intent to advance KT-474 into Phase 2 clinical trials. Phase 2 clinical trials of KT-474 will initially investigate its potential in HS and AD, with the clinical trial for the first indication initiating in 2023. With respect to our oncology programs, we are evaluating KT-333, a STAT3 degrader, in a Phase 1 clinical trial in patients with relapsed/refractory liquid and solid tumors, including aggressive lymphomas. Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023. We are also evaluating KT-413, our IRAKIMiD degrader, in a Phase 1 clinical trial in patients with relapsed/refractory B cell lymphomas, including MYD88 mutant diffuse large B cell lymphomas (DLBCL). Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023. In December 2022, we received FDA clearance for our investigational new drug, or IND, application to evaluate our MDM2 degrader, KT-253, in a Phase 1 clinical trial. KT-253 has been developed to stabilize the tumor suppressor p53 and address a wide variety of p53 wild type tumor types in both solid tumors and hematologic malignancies. We plan to initiate our Phase 1 clinical trial of KT-253 in early 2023.

Our Strategy

Our mission is to discover, develop and commercialize novel and transformative therapies that improve the lives of patients with serious diseases, and we are committed to the selection of targets that enable a broad impact across multiple clinical indications with high unmet medical need. We believe the unique discovery capabilities of our PegasusTM platform will position us to be a leader in the area of TPD. Our goal is to become a fully integrated biopharmaceutical company with a pipeline of novel degrader medicines targeting disease-causing proteins that were previously intractable. We intend to achieve this goal by pursuing the following strategic objectives.

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Background of Targeted Protein Degradation

Proteins are responsible for the structure, function and regulation of tissues and organs. Cells in the body continuously synthesize and degrade proteins, maintaining an equilibrium called protein homeostasis. Most diseases are the result of aberrant protein behavior driven by activation, mutation, or downregulation of the protein itself, or by the gene responsible for the transcription and translation of that particular protein. With a deepened molecular understanding of various diseases and the characterization of the full human genome, research efforts have increasingly focused on the development of medicines to address malfunctioning proteins responsible for oncologic, auto-immune, cardio-metabolic, neurodegenerative, and rare genetic diseases.

The ‘druggable’ genome challenge

Several therapeutic modalities have been developed over the years to address aberrant protein activity. These have included small molecule inhibitors of protein function, therapeutic antibodies, oligo-based therapeutics such as RNA interference therapeutics, antisense oligonucleotides, or ASO, and other genetic therapies.

Some of these modalities have had a tremendous impact on the treatment of diseases and quality of life of patients, and several others, while earlier stage, offer potential. However, these traditional modalities face specific challenges that limit their therapeutic impact and reach. Some of the limitations of existing modalities include the following:

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As a result of these limitations, we believe that only 20% of the full human genome has been effectively drugged to date. New therapeutic modalities which can overcome some of these challenges are necessary to expand the drugged proteome/genome and provide new efficacious medicines to patients in need. We believe that TPD is such a modality.

Figure 1. Expanding the Druggable Human Proteome.

Targeted Protein Degradation

One of the methods that cells use to control the balance between the synthesis of new proteins and the degradation and disposal of damaged and/or misfolded proteins, is ubiquitin-proteasome system, or UPS. The discovery of ubiquitin-mediated protein degradation provided important insights into specific processes like cellular division and DNA repair and led to the discovery of UPS’ critical roles in various cellular pathways, including the cell cycle, signaling pathways, the regulation of gene expression, and responses to oxidative stress. The discovery of the UPS also revealed a new modality to harness this cellular process for the treatment of diseases.

The UPS comprises a series of finely orchestrated enzymatic sequences that ultimately lead to protein polyubiquitination and degradation by the proteasome in cells. Protein ubiquitination is a cellular process involving an enzymatic cascade consisting of ubiquitin-activating enzymes (E1), ubiquitin-conjugating enzymes (E2), and ubiquitin-protein ligases (E3). In humans, there are two classes of ubiquitin activating E1 enzymes, more than 30 E2 enzymes, and approximately 600 E3 ligases.

As illustrated in the figure below, the E3/E2/ubiquitin ligase complex (shown in blue) binds to a substrate protein (shown in purple) to mediate the transfer of ubiquitin, which leads to degradation of the target protein through the proteasome.

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Figure 2. Natural Protein Degradation Through Ubiquitin-Proteasome System.

Targeted protein degradation is a new modality that co-opts this innate cellular process. The core of the TPD modality consists of a small molecule (shown in magenta in Figure 3 below) that we refer to as a heterobifunctional degrader. The role of this heterobifunctional degrader molecule is to mediate a “new” interaction through the formation of a ternary complex between a disease-causing protein and an E3 ligase. The E3 ligase tags the protein target for degradation by attaching a series of ubiquitin, and the proteasome recognizes the tagged protein and degrades it into small peptides.

Forming an efficient ternary complex, as shown in step 2 in the figure below, is a critical step in TPD, and its formation, function, and effect on cellular and in vivo systems is vital to the success of the degradation and its impact on disease. In addition, the degrader molecule needs to be able to effect degradation in a variety of different cell types and contexts and have the right pharmaceutical properties to be therapeutically dosed to patients.

As shown in the figure below, after the degrader facilitates the ubiquitination of the target protein, and as the protein is degraded by the proteasome, the molecule separates from the protein, and is able to form another ternary complex to conduct the degradation process again. This iterative mechanism is catalytic, which results in increased potency even at lower concentrations, another key differentiator from other modalities such as small molecule inhibitors and therapeutic antibodies.

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Figure 3. Overview of Targeted Protein Degradation.

Due to the unique advantages of TPD, this transformative modality is capable of targeting proteins traditionally undrugged by small molecules. Specifically, TPD can target proteins without a catalytic function such as scaffolding proteins and transcription factors, with small molecule-like drug properties that can potentially be dosed orally and distributed systemically unlike oligo-based therapeutics such as RNAi’s. TPD molecules also are amenable to existing small molecule manufacturing principles which are less costly than other therapeutic modalities. Because of the catalytic nature of the degradation process, we believe the modality has the potential to be therapeutically effective with smaller amounts of drug substance and less frequent dosing than traditional therapeutics.

The use of small molecules to affect protein homeostasis has been clinically and commercially validated by multiple drugs over the past two decades. Drugs such as bortezomib and fulvestrant have been understood to inhibit the proteasome and target the estrogen receptor for proteasome-dependent degradation, respectively. More recently, immunomodulatory imide drugs such as lenalidomide and pomalidomide have been understood on a post-hoc basis to direct the degradation of a series of transcription factors via the UPS.

These immunomodulatory drugs have validated the concept of using the UPS to degrade proteins and elicit a pharmacological and therapeutic effect in disease settings. However, unlike earlier approaches in this field, TPD takes this proven concept further to prospectively target the degradation of a wider range of proteins through the rational design of heterobifunctional degraders which coordinate the discreet binding of target proteins and E3 ligases to drive the desired protein degradation.

An important factor for the efficiency of a degrader is the specificity and affinity to the targeted E3 ligase. The various E3 ligases have different distribution and cellular localization profiles that are important factors when considering which E3 ligase to use for a particular disease protein target. There are approximately 600 E3 ligases that occur in nature, but to date only a handful of these E3 ligases have been evaluated for therapeutic purposes, leaving a substantial portion of the genome available for targeting.

Our PegasusTM Platform

Our proprietary drug discovery platform, called PegasusTM, enables us to rationally design targeted protein degraders that have the potential to drug all target classes in the cell. Our approach is rooted in an understanding of the relationship between E3 ubiquitin ligases and target proteins, which allows us to identify the properties that make a target both ligandable and degradable, and determine how multiple factors impact potency, selectivity, pharmacokinetics, or PK, and pharmacodynamics, or PD. Key components of our platform include our E3 ligase ligand toolbox, our understanding of degradation across healthy and diseased tissue types, our proprietary chemistry and our Center for Molecular Glue Discovery.

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Our Therapeutic Pipeline

Our current clinical-stage programs are IRAK4, IRAKIMiD, STAT3 and MDM2, which each focus on a single critical signaling node within the genetically and clinically validated IL-1R/TLR, JAK/STAT and p53 pathways.

We completed our Phase 1 clinical trial for KT-474 in October 2022. Patient enrollment and dosing are ongoing for our Phase 1 clinical trials for KT-333 and KT-413. In December 2022, we announced we received FDA clearance of our IND to evaluate our MDM2 degrader, KT-253 and we expect to start enrollment in the Phase 1 study in early 2023.

The following table summarizes our clinical stage pipeline. We also have multiple programs in earlier stages of development and are exploring targets in therapeutic areas outside of our core areas of focus:

Our IRAK4, IRAKIMiD, STAT3 and MDM2 Programs

We are developing KT-474, a highly active and selective, orally bioavailable IRAK4 degrader, for the treatment of IL-1R/TLR-driven immunology-inflammation conditions and diseases with high unmet medical need, including HS, an inflammatory skin disease, as well as AD and RA. We have chosen to pursue IRAK4 degradation due to the well-validated role of the IL-1R/TLR pathway in immunology and inflammation and the potential advantage that drugging a single node of multiple different mediators of inflammation has over other approaches focused on targeting one of many cytokines that stimulate the IRAK4 node. IRAK4 is a critical node in the IL-1R/TLR signaling pathway, which is dependent on both IRAK4’s kinase activity and scaffolding function. We have observed through our in vitro and in vivo studies that KT-474 induces IRAK4 degradation, impacting both the kinase and the scaffolding functions, and therefore can efficiently and selectively block IL-1R/TLR-mediated inflammation in a way we believe to be superior to IRAK4 kinase inhibitors. We therefore believe KT-474 has the potential to improve outcomes over current treatment options as well as other drugs currently in development. The dose

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escalation in the SAD and MAD portions of this Phase 1 trial in healthy volunteers was completed in December 2021. In October 2022, we announced that we had completed the patient cohort, or Part C, of the KT-474 Phase 1 trial, which included hidradenitis suppurativa, or HS, and atopic dermatitis, or AD, patients. We are collaborating with Sanofi on the development of drug candidates targeting IRAK4 outside of oncology and immuno-oncology fields, and in December 2022, Sanofi notified us of its intent to advance KT-474 into Phase 2 clinical trials in patients with HS and AD . See “Business—Collaborations—Collaboration Agreement with Sanofi.”

We are developing another group of IRAK4 degraders, which we call IRAKIMiDs, with a unique profile that combines the activity of IRAK4 degradation and immunomodulatory imide drugs, or IMiDs, for the treatment of MYD88-mutated diffuse large B-cell lymphoma, or DLBCL. In oncology, IRAK4 is an obligate protein in MYD88 signaling and this activated mutation is well characterized to drive oncogenesis. IMiDs are a class of drugs that degrade zinc-finger transcription factors, such as Ikaros and Aiolos, resulting in the restoration of Type 1 interferon, or Type 1 IFN, signaling pathway which is relevant in treating lymphoma. Our IRAKIMiDs combine the activity of the IMiDs with IRAK4 degradation in a single agent and address both the IL-1R/TLR and the Type 1 IFN pathways synergistically and in doing so are designed to produce broad activity against MYD88-mutant lymphomas. In animal models, we have demonstrated that this combination in a single agent is superior to co-administering IRAK4 and IMiD agents. We believe this will be the first precision medicine in lymphoma to target a genetically defined population, which accounts for approximately 25% of DLBCL patients. We have observed that the functional synergy between the degradation of IRAK4 and IMiD activity results in broad activity against MYD88-mutant lymphomas in vitro and in mouse xenograft models, leading to rapid, complete and sustained tumor regressions, even when dosed intermittently. Further, we have seen additive and synergistic activity in vivo combining IRAKIMiD with ibrutinib (BTK), venetoclax (BCL-2 inhibitor), and rituximab (anti-CD20 monoclonal antibody), which are important back-bone therapies in these B cell lymphomas. We are currently evaluating our IRAKIMiD degrader, KT-413, in a Phase 1 clinical trial in patients with relapsed/refractory B cell lymphomas, including MYD88 DLBCL. Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023.

We are developing our selective STAT3 degraders for the treatment of hematological malignancies and solid tumors, as well as autoimmune diseases and fibrosis. STAT3 is a transcription factor activated through a variety of different cytokine and growth factor receptors via janus kinases, or JAKs, as well as through oncogenic fusion proteins and mutations in STAT3 itself. We believe the diverse functions of STAT3 in tumor biology, evasion of immune surveillance by tumor cells, and inflammation and fibrosis provide opportunities to address a wide variety of high unmet need disease indications through the targeting of a single genetically and clinically validated pathway. While the JAK-STAT pathway has been partially addressed with several clinically successful JAK-targeting agents, we believe there are currently no drugs that specifically affect STAT3 broadly across all the relevant cell types. Small molecule STAT3 dimerization inhibitors targeting the SH2 domain have been in development, but significant challenges remain: first, homology of SH2 domains among all STAT family members impacts the ability to achieve specificity for STAT3, and second, inability to block dimerization independent transcriptional activities of STAT3. For these reasons, we believe that STAT3 degraders may provide a transformative solution to the development of targeted and selective drugs to address multiple STAT3 dependent pathologies. We are currently evaluating our STAT3 degrader, KT-333, in a Phase 1 clinical trial in patients with relapsed/refractory liquid and solid tumors, including aggressive lymphomas. Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023.

We are developing degraders that target MDM2 for the treatment of solid tumors and hematological malignancies. MDM2 is the crucial regulator of the most common tumor suppressor, p53, which remains intact (or wild type) in more than 50% of cancers. Unlike small molecule inhibitors, our MDM2 degrader, KT-253, has been shown preclinically to have the ability to overcome the MDM2 feedback loop and rapidly induce apoptosis, even with brief exposures. In December 2022, we announced that we received clearance from the FDA for our IND for KT-253. We plan to initiate a Phase 1 clinical trial of KT-253 in early 2023, which is designed to evaluate the safety, tolerability, PK/PD and clinical activity of KT-253 in adult patients with liquid and solid tumors.

Our Approach to Target Selection

We maintain a unique approach to target selection within the TPD field focused on targets within three distinct categories, as described below and shown in Figure 4.

Inadequately Drugged (ID). We are focused on targets that have been inadequately drugged with other technologies and, importantly, where degradation provides a clear advantage over enzyme inhibition. We have identified and targeted proteins where removal offers superior therapeutic benefit versus inhibition of enzymatic activity or blockade of a binding site. Examples of targets we are pursuing in this category include IRAK4 and MDM2.

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Undrugged Targets (UD). We are also exploring targets that are traditionally undrugged using other technologies. In some instances, ligands to these targets may exist and, while inadequate on their own for inhibition, have potential to serve as part of a heterobifunctional targeted protein degraders. In other instances, undrugged targets may have no known ligands and potentially no accessible small molecule binding sites which may make them poor candidates for both inhibitors and current heterobifunctional molecules. In these instances, we are pursuing a molecular glue approach in which a new surface on an E3 ligase is created via a small molecule with potential to engage the protein target of interest through a specific protein-protein interaction. An example of a target we are pursuing in this category is STAT3.

Tissue Restricted (TR). The final category of targets includes targets which can uniquely be accessed using our proprietary human whole body E3 ligase Atlas. Our efforts here are focused on systematically identifying tissue sparing and tissue selective E3 ligases, which enables us to access clinically validated targets where on-target, unwanted pharmacology limits the clinical utility of small molecule inhibitors. We are currently working on several programs, at different stages of development, pursuing tissue restricted or selective degradation.

Figure 4. Our Approach to Target Selection

Our Programs

IRAK4 Degrader for IL-1R/TLR-driven Immunology-inflammation Diseases

Summary

We are developing KT-474, a highly active and selective, orally bioavailable IRAK4 degrader, for the treatment of IL-1R/TLR-driven immune-inflammatory conditions and diseases with high unmet medical need, including HS, AD, RA and others. We have chosen to pursue IRAK4 degradation due to the well-validated role of the IL-1R/TLR pathway in immunology and inflammation and the potential advantage that drugging a single node of multiple different mediators of inflammation has over other approaches focused on targeting one of many cytokines that stimulate the IRAK4 node. IRAK4 is a critical node in the IL-1R/TLR signaling pathway, which is dependent on both IRAK4’s kinase activity and scaffolding function. We have observed through our in vitro and in vivo studies that KT-474 induces IRAK4 degradation, impacting both the kinase and the scaffolding functions, and therefore can selectively block IL-1R/TLR-mediated inflammation in a way we believe to be superior to IRAK4 kinase inhibitors. We therefore believe KT-474 has the potential to improve outcomes over current treatment options as well as other drugs currently in development. The dose escalation in the SAD and MAD portions of this Phase 1 trial in healthy volunteers was completed in December 2021. In October 2022, we announced that we had completed the patient cohort, or Part C, of the KT-474 Phase 1 trial, which included HS and AD patients. We are collaborating with Sanofi on the development of drug candidates targeting IRAK4 outside of oncology and immuno-oncology fields, and in December 2022, Sanofi notified us of its intent to advance KT-474 into Phase 2 clinical trials in patients with HS and AD initially potentially

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followed by other indications. See the section entitled “Business—Collaborations—Collaboration Agreement with Sanofi” appearing elsewhere in this Annual Report for more information.

Biology and Mechanism of Action of IRAK4 Degrader

IRAK4 is a key component of the myddosome, a multiprotein complex involved in innate immunity that mediates signaling through TLRs and IL-1Rs. The IRAK4 protein is ubiquitously expressed across multiple different tissue types, including skin, lymphoid tissue, bone marrow, gastrointestinal tract, and lung.

The function of IRAK4 is dependent both on its kinase activity and on its scaffolding function, which are required for the assembly of the myddosome complex following TLR or IL-1R engagement and MYD88 activation. While the kinase function is primarily responsible for the phosphorylation events in the IRAK4-JNK axis, the scaffolding function is primarily responsible for the NF-KB activation and downstream gene traction of several key pro-inflammatory cytokines and chemokines.

We believe IRAK4 degradation is superior to IRAK4 kinase inhibition as our preclinical data suggests that it is critical to block both the kinase activity and scaffolding functions of the IRAK4 protein, which requires removal, as opposed to just inhibition, of the protein. IL-1 family cytokines, including IL-1a, IL-1ß, IL-18, IL-36, and IL-33, have been implicated in a variety of different immunology-inflammation conditions and diseases. As both TLRs and IL-1Rs are involved in the production and response to all of these IL-1 family cytokines, IRAK4 targeting with a single small molecule degrader could impact multiple different cytokines and chemokines and thereby provide a transformative approach to the treatment of IL-1R/TLR-driven diseases.

Figure 5. IRAK4 Function is Comprised of Both Kinase-Dependent and -Independent Activity.

Development Opportunities and Differentiation from IL-1 Family Cytokine Antibodies

There are numerous cutaneous, rheumatic and gastrointestinal immunology-inflammation disease indications for which pathogenesis involves IL-1 family cytokines as well as TLR stimulation. These present opportunities where we believe a highly efficient and selective IRAK4 degrader would provide significant advantages over both currently approved treatment options and those in clinical development. We are initially prioritizing indications such as HS, AD, and RA where there is clinical proof of concept for targeting cytokines impacted by the IL-1R/TLR pathway but for which there continues to be a high level of unmet need.

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Figure 6. IL-1 Family Cytokines

Hidradenitis Suppurativa

HS is a chronic, destructive, painful and debilitating inflammatory skin disease affecting up to 1% of both the U.S. and global population. Patients with HS have numerous painful, draining nodules and abscesses, usually within skin folds, that are characterized by inflammation and bacterial colonization. Currently HS is treated symptomatically with corticosteroids, antibiotics and surgery. The only FDA-approved treatment for HS is the anti-TNF antibody adalimumab, which provides some benefit to approximately 50% of patients with moderate-to-severe disease but is not curative. Thus, there remains a high unmet need for better therapies for the treatment of HS.

Bacterial activation of TLRs, as well as the production of IL-1a, IL-1ß, and IL-36 by keratinocytes and inflammatory cells leading to inflammation characterized by high levels of TNF-a, IL-6, and IL-17, are central to the pathogenesis of HS. Monoclonal antibodies targeting individual cytokines such as IL-1a (bermekimab), IL-1a/ß receptor (anakinra), and IL-17 (secukinumab and bimekizumab) have shown preliminary clinical activity in HS and provide clinical validation for targeting the IL-1R/TLR pathway in HS. As such, an IRAK4 degrader which acts on multiple cytokines as well as TLRs has the potential to offer a significant advantage over the single-cytokine-targeting agents currently being developed.

Atopic Dermatitis

AD is a chronic, pruritic inflammatory skin disease that occurs most frequently in children but also affects adults. In the major global markets, the diagnosed prevalence of AD is estimated over 60 million patients, with approximately 40%, or 24 million, falling into the moderate-to-severe category. AD follows a chronic relapsing course over month to years, with dry skin and severe pruritus as the primary symptoms, sometimes accompanied by skin thickening from chronic scratching and fissuring. AD is treated symptomatically with topical therapies, including emollients, corticosteroids, and phosphodiesterase inhibitors. The lone FDA-approved systemic treatment is the IL-4Ra targeting antibody dupilumab, though only approximately 40% of moderate-to-severe disease patients met the primary endpoint in its Phase 3 trials, leaving a significant percentage of patients who are currently underserved.

Furthermore, there is evidence that IL-33 and IL-1 are both involved in the generation of inflammation in both AD and other allergic diseases, including eosinophilic asthma and chronic rhinosinusitis. Single-cytokine-targeting monoclonal antibodies against IL-33 (etokimab) and IL-1a(bermekimab) have shown preliminary clinical activity in AD. Thus, we believe the ability of an IRAK4 degrader to impact the production of both IL-33 and IL-1, through complete TLR signaling blockade, and the cellular response to both cytokines, through complete IL-1R signaling blockade, provides a compelling mechanistic rationale for development in AD.

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Rheumatoid Arthritis

RA, an additional potential indication for our IRAK4 degrader, is the most common inflammatory arthritis, affecting approximately 5 million individuals in the 7 major markets worldwide, with a prevalence of 0.7% of the U.S. population. The synovial inflammation characteristic of RA is driven by Th1 and Th17 immune responses with production of TNF-a and IL-1 family cytokines, including IL-1, IL-18 and IL-33, IL-6 and IL-17. Multiple therapies targeting the IL-1R/TLR pathway are approved for RA, and recently an IRAK4 kinase inhibitor (PF-06650833) has shown clinical activity comparable to the JAK inhibitor tofacitinib and a favorable safety profile in a randomized, placebo-controlled Phase 2b study in RA patients with inadequate response to methotrexate. Based on these early signs of activation, we believe a degrader-based approach which impacts both the kinase activity and the scaffolding function of IRAK4 may have the potential for a more transformative effect on the disease.

Clinical Studies and Data

In December 2021, we completed dose escalation in the SAD and MAD portions of the KT-474 Phase 1 trial. The following figure summarizes the trial design of the healthy volunteer portion of the trial.

Figure 7: KT-474 Healthy Volunteer Study

The summary of key findings in the healthy volunteer portion of the KT-474 clinical trial included:

Following the healthy volunteer portion of the trial, we completed a single dose, food-effect cohort to establish the dose for the patient cohort, or Part C, of the KT-474 Phase 1 trial, which included HS and AD patients and which was completed in October 2022.

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Part C enrolled 21 patients, the demographics of which are shown below in Figure 8.

Figure 8: KT-474 Part C Baseline Demographics

The Part C baseline disease characteristics are shown below in Figure 9. One HS patient withdrew for personal reasons after dose 4, and one AD patient withdrew for personal reasons after dose 5.

Figure 9: KT-474 Part C Baseline Disease Characteristics

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As shown below in Figure 10, the KT-474 plasma PK at the 75 mg once daily (QD) dose (in the fed state) in patients was comparable to healthy volunteers in the MAD portion of the Phase 1 clinical trial who received 100 mg once daily in the fasted state, the MAD cohort which we refer to as MAD3. Additionally, mean Cmax (6-hour post dose concentration) and Ctrough (pre-dose concentration) levels at steady state in Part C were in line with MAD3 levels at Day 14, and the mean half-life of 44 hours was within the range observed in MAD (34-59 hours)

Figure 10: Part C KT-474 Plasma PK

As shown in Figure 11, KT-474 concentrations in plasma led to a comparable level of IRAK4 degradation in healthy volunteers and HS/AD patients. Specifically, at concentrations above 3 ng/mL degradation was generally above 80% in both populations. Additionally, IRAK4 levels in PBMC in patients with evaluable samples were near the lower limit of quantification at Day 28.

Figure 11: PK/PD Correlation in Plasma/Monocytes (FLOW)

Baseline IRAK4 levels in skin lesions of evaluable HS and AD patients were approximately twice the levels of healthy volunteers. By Day 28 of dosing, the mean IRAK4 in skin lesions of AD and HS patients was reduced to approximately the same level as healthy subjects, as shown below in Figure 12.

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Figure 12: IRAK4 Levels in Skin Lesions

KT-474 was generally well-tolerated. There were no serious adverse events, no drug-related infections, and no adverse events observed leading to dose interruption or discontinuation. The below figure lists adverse events related to study drug occurring in greater than 1 Patient.

Figure 13: KT-474 Part C Adverse Events

In addition, a modest, non-adverse QTc prolongation, consistent with that observed by Day 7 in the MAD portion of the healthy volunteer study, was also observed in the patient cohort but spontaneously resolved back to baseline with continued dosing during the 28-day dosing period.

A whole blood ex vivo stimulation assay using the TLR ligands LPS or R848 showed broad inhibition of multiple disease-relevant cytokines and chemokines of up to 84-98% in HS and AD patients from Days 14 to 28, comparable or superior to what was observed in the healthy volunteer MAD3 cohort, as shown below in Figure 14.

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Figure 14: KT-474 Whole Blood ex vivo stimulation

To determine whether KT-474 had a systemic anti-inflammatory effect in HS and AD patients, plasma levels of IL-6, CRP, SAA and IL-1b were measured at baseline and at various times during and after the 28-day treatment period. In patients whose baseline levels were greater than the upper limit of normal, the evaluable patients showed suppression of all 4 analytes, with mean maximum reductions through Day 42 ranging from 41 to 63%, as shown below in Figure 15.

Figure 15: Plasma Levels

Part C also evaluated how systemic IRAK4 degradation in blood and skin would affect the expression of proinflammatory genes known to be relevant to either AD or HS. Figure 16 illustrates select disease-relevant genes downregulated in skin lesions of at least 50% of AD or HS patients at Day 28 compared to baseline. In AD, affected genes included the Th2 cytokine IL-5, the inflammasome NLRP3, as well as CXCL1 and IL-2RB. Genes affected in HS included IL-1 family cytokines IL-1 and IL-36A, mediators of Th1 inflammation such as IFN-g and GZMB, the Th17 cytokine IL-17A, and drivers of innate immunity such as IL-8 and CSF3. The downregulation was substantial with many genes inhibited more than 90% in both diseases.

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Figure 16: Disease-relevant biomarkers

Part C included exploratory clinical endpoints used for HS and AD. The endpoints were chosen in order to assess the effect of KT-474 treatment on the burden of skin disease as well as on symptoms such as pain and pruritus that impact quality of life for HS and AD patients.

In AD patients, as shown in Figure 17, there was a mean 37% reduction in skin lesions as measured using the Eczema Area and Severity Index (EASI) score, with reductions in individual patients of up to 76%. Maximum reduction was seen by Day 28 and was maintained at Day 42.

Figure 17: Mean EASI Score Over Time (n=7)

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As shown in Figure 18, mean peak pruritus in AD patients over the past week or past 24 hours was reduced by 52% and 63%, respectively, with maximum reductions occurring by Day 42. Peak pruritus responders, defined as ≥4 Unit reduction in peak pruritus over the past week or past 24 hours, were seen in 57% and 71% of AD patients, respectively, with responses sustained after Day 28.

Figure 18: Peak Pruritus Numerical Rating Scale in AD patients

The Validated Investigator’s Global Assessment (vIGA) of disease severity improved in 2 of 7 AD patients and remained stable in the others out to Day 42, as shown in Figure 19.

Figure 19: vIGA-AD Score Over Time (n=7)

In HS patients, the efficacy analyses were performed in all patients, which included two patients with very severe disease. In addition, efficacy analyses were also performed in a subset of HS patients that only had moderate to severe disease, which was the target population for this study. As shown in Figure 20, the AN count was reduced by up to an average of 46% in all HS patients and of 51% in the moderate to severe subset, with reductions in individual patients of up to 100% and with maximum reduction occurring by Day 42. The proportion of patients achieving an AN count of 0, 1 or 2 at Day 28 was 42% in all HS patients and 50% in those with moderate to severe disease.

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Figure 20: AN count over time

HiSCR50 response is defined as a 50% or greater reduction in AN count and no increase in abscesses or draining fistulas. As shown in Figure 21, at Day 42, the proportion of HiSCR50 responders was 42% in all HS patients and 50% in those with moderate to severe disease.

Figure 21: % of Patients with HiSCR50

HiSCR75 response, defined as 75% or greater reduction in AN count, was seen in 25% of all HS patients and 30% of those with moderate to severe disease.

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Symptoms of pain and pruritus were also measured. As shown in Figure 22, there was a 49 to 55% mean reduction in the Pain Numerical Rating Scale, or NRS, in all HS patients and in those HS patients with moderate to severe disease, respectively, with maximum reduction occurring between Days 28 and 42. Pain NRS30 response is defined as at least a 30% reduction and at least one unit reduction from baseline in Pain NRS. As also shown in Figure 22, the Pain NRS responder rate was 50% in all HS patients and 60% in those HS patients with moderate to severe disease, sustained after Day 28.

Figure 22: Pain Numerical Rating Scale in HS patients

As shown below in Figure 23, there was a mean reduction in peak pruritus of 62% in all HS patients and 68% in those HS patients with moderate to severe disease, with maximum reduction by Day 42 in all HS patients and by Day 28 in those with moderate to severe disease.

Figure 23: Mean % Change in Peak Pruritus Over Past Week

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The Physician’s Global Assessment of disease severity improved in 5 HS patients, including clearing of disease in 1 patient with moderate disease at baseline, and remained stable in the other evaluable patients out to Day 42, as shown in Figure 24.

Figure 24: Physician’s Global Assessment (HS-PGA)

Clinical Development Plan

On December 14, 2022, we announced that Sanofi notified us of its commitment to advance KT-474 into Phase 2 clinical trials in 2023. Phase 2 clinical trials of KT-474 will initially investigate its potential in HS and AD with the first clinical trial for the first indication planned for initiation in 2023.

IRAKIMiD Program in Oncology

Summary

We are developing another group of IRAK4 degraders, which we call IRAKIMiDs, with a unique profile that combines the activity of IRAK4 degradation and IMiDs for the treatment of MYD88-mutated DLBCL. In oncology, IRAK4 is an obligate protein in MYD88 signaling and this activated mutation is well characterized to drive oncogenesis. IMiDs are a class of drugs that degrade zinc-finger transcription factors, such as Ikaros and Aiolos, resulting in the restoration of Type 1 IFN signaling pathway which is relevant in treating lymphoma. Our IRAKIMiDs combine the activity of the IMiDs with IRAK4 degradation in a single agent and address both the IL-1R/TLR and the Type 1 IFN pathways synergistically with a goal of demonstrating broad activity against MYD88-mutant lymphomas. We believe this will be the first precision medicine in lymphoma to target a genetically defined population, which accounts for at least 25% of the estimated approximately 150,000 DLBCL patients currently diagnosed in the major global markets. We have observed the degradation of IRAK4 and IMiD activity results in additivity and synergy in vitro. IRAKIMiDs combine both of these mechanisms in a single compound. Our IRAKIMiD degrader, KT-413, has been observed to have broad activity against MYD88-mutant lymphomas in vitro and in mouse xenograft models, leading to rapid, complete and sustained tumor regressions, even when dosed intermittently. We are currently evaluating our IRAKIMiD degrader, KT-413, in a Phase 1 clinical trial in patients with relapsed/refractory B cell lymphomas, including MYD88 mutant DLBCL. Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023.

Target Rationale and Mechanism of Action

In DLBCL, the activating mutation of MYD88 drives activation of the NF-KB transcription factor and pro-survival mechanisms such as IRF4. MYD88 is a protein that forms a multiprotein signaling complex, known as the myddosome, which transduces receptor agonism from both the TLR and IL-1 b receptors. IRAK4 is an integral component of the myddosome, and both its catalytic kinase activity as well as its scaffolding function are required to drive downstream signals from the myddosome.

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The constitutive activation of NF-KB is a hallmark of several B-cell lymphoma subtypes. In DLBCL, NF-KB activation is driven by a range of oncogenic alterations in several upstream pathways and regulators. Multiple co-mutations in these complexes often occur within the same tumor, emphasizing the dependence of these cancers on NF-KB activation. IMiDs such as lenalidomide drive a partial downregulation of NF-KB and IRF4, resulting in the restoration of Type 1 IFN signaling and promoting cell death.

Figure 25. NF-KB is Activated by Complimentary Mechanisms in Diffuse Large B Cell Lymphoma.

Leveraging knowledge and chemistry expertise derived from the design of our selective IRAK4 degrader program, we have designed a novel class of heterobifunctional IRAK4 degraders, which we call IRAKIMiDs, that utilize an active IMiD as the cereblon binder to simultaneously engage and degrade both IRAK4 and IMiD substrates, such as Ikaros and Aiolos, thus combining the activity of two molecules in a single agent. IRAKIMiDs therefore combine two highly relevant therapeutic mechanisms in a single compound, enabling the functional synergy of NF-kB inhibition and upregulation of the Type 1 IFN response that results in increased and broader single-agent activity in MYD88-mutated DLBCL as compared to either mechanism alone.

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Figure 26. IRAKIMiDs (right) Combine Both IRAK4 Degradation and IMiD Activity in a Single Agent.

Development Opportunities and Differentiation of Novel Therapies in MYD88-Mutated DLBCL

Oncogenic mutations of MYD88, most commonly MYD88L265P, are common in several subsets of DLBCL. In particular, MYD88 is estimated to be mutated in approximately 30-40% of activated B cell DLBCL, or ABC-DLBCL, cases; 30-80% of primary CNS lymphoma cases; and 45-75% of primary extranodal lymphomas cases. In addition, MYD88 is mutated in approximately 90% of Waldenström macroglobulinemia cases. The presence of MYD88 mutations in DLBCL is often associated with poorer response to chemotherapy and reduced overall survival compared to other genetic subtypes, supporting the need for more effective therapies targeting MYD88-mutated DLBCL.

Front-line treatment of DLBCL typically involves the R-CHOP treatment regimen of chemotherapy combined with rituximab. While effective in many other patients, front-line chemotherapy has significantly poorer survival rates in DLBCL subsets where MYD88 mutations are prevalent. In additional lines of therapy, several novel targeted therapies have been approved recently, including the combination of polatuzumab, bendamustine and rituximab, as well as CD19-targeting chimeric antigen receptor T-cells. While these agents have some notable activity, many patients fail to respond to or subsequently relapse from these therapies, with no adequate treatment options. Several targeted therapies that impact the NF-kB pathway, such as the Bruton’s tyrosine kinase inhibitor ibrutinib, or the IMiD lenalidomide, have shown modest single agent activity, with poor durability of response in MYD88-mutated DLBCL.

Based on our preclinical data, we believe KT-413, which synergistically combines the activity of both IRAK4 and IMiD substrate degradation to exploit complimentary pathway signaling, will have the potential to improve upon the efficacy of IRAK4 kinase inhibitors and other therapies, including BTK inhibitors and IMiDs, and provide single-agent activity in MYD88-mutated DLBCL.

Preclinical Studies and Data

In support of our preclinical development, we have observed our IRAKIMiD degraders’ high selectivity and therapeutic potential in both in vitro and in vivo studies.

To assess the activity of our IRAKIMiD degraders in both MYD88-mutated and -wild-type cells lines, we conducted various in vitro studies in a panel of cell lines. MYD-88-mutated cell lines included ABC-DLBCL lines such as OCI-Ly10, SUDHL2, and TMD8 while MYD-88-wild-type cell lines included OCI-Ly19, U2932, and SUDHL6. We have shown that IRAK4 degradation, as opposed to IRAK4 inhibition, shows additivity and synergy when combined with IMiDs in vitro. Specifically, combining an IRAK4 degrader with the IMiD pomalidomide shows additive and synergistic activity in several MYD88-mutated cell lines in vitro, supporting the combined effect of targeting both the MYD88 and IRAK4 pathways together. Notably, we did not see an additive effect when IRAK4 kinase inhibitors were combined with IMiDs, suggesting that the greater activity of IRAK4 degradation is needed for synergistic activity. We believe these data support the development of our unique class of IRAKIMiD degraders.

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KT-413 is a potent degrader of IRAK4 and the IMiD substrates, Ikaros and Aiolos with single digit nM DC50 values against all three targets with maximal growth inhibition observed with approximately 80% target knockdown. As shown in Figure 27, KT-413 is more potent and more active in MYD88-mutated DLBCL than either an IRAK4-selective degrader compound, or a clinically active IMiD, supporting our hypothesis that simultaneous degradation of IRAK4 and IMiD substrates is more effective than degrading either alone.

Figure 27. KT-413 Potency

Figure 28 summarizes results of in vivo experiments in xenograft models of MYD88 mutant DLBCL demonstrating profound antitumor activity with durable complete responses in animals treated with KT-413 on intermittent dosing schedules as infrequent as every 2 or 3 weeks. As shown, this level of activity is superior to that of an IRAK4 kinase inhibitor or the clinically active latest generation IMiD compound.

Figure 28. KT-413 In vivo xenograft models

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Figure 29 highlights the unique PK/PD properties of KT-413 that result in protracted tumor exposure and robust knockdown of the targets for at least 72 hours, committing tumor cells to apoptosis that leads to tumor regressions.

Figure 29. Super Anti-Tumor Activity

In addition to the robust single agent antitumor effects of KT-413, Figure 30 summarizes the combination data with agents used in the treatment of lymphoma. In these experiments conducted in MYD88 mutant DLBCL models, sub-optimal doses of KT-413 combined with ibrutinib (BTK) venetoclax (BCL-2 inhibitor), or rituximab (Rituxan, an anti-CD-20 monoclonal antibody), showed deep and durable regressions highlighting the potential of KT-413 combination to be used in earlier lines of therapy in patients with MYD88 mutant lymphoma.

Figure 30. KT-413 Combination therapy

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Clinical Studies and Data

In 2022, we initiated our Phase 1 clinical trial of KT-413 to evaluate the safety, tolerability, PK/PD and clinical activity of KT-413 administered as an intravenous, or IV, infusion once every 3 weeks to adult patients with relapsed and/or refractory B-cell non-Hodgkin’s lymphomas. Figure 31 below shows the details of the trial design.

Figure 31: KT-413 Phase 1 Clinical Trial Design

In December 2022, we announced that dose level 1 (0.16 mg/kg) and dose level 2 (0.32 mg/kg) were completed. Patients in both dose cohorts were heavily pretreated, having received multiple prior lines of therapy, and included follicular lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma, which were both wild-type for MYD88. Plasma PK and PD translated as we expected in humans with dose level 1 and dose level 2 showing dose-dependent degradation of IRAK4, Ikaros and Aiolos in PBMC, with up to 95/100% knockdown of Ikaros/Aiolos and 40% knockdown of IRAK4 in dose level 2 as summarized below in Figure 32.

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Figure 32: Target Degradation in PBMC by FLOW

Figure 33 highlights that serial tumor biopsies at Cycle 3/Day 4 in the patient treated at dose level 1 showed comparable knockdown of Ikaros/Aiolos and IRAK4 as in plasma.

Figure 33: Target Knockdown in Tumor by Targeted MS

There were no dose limiting toxicities or treatment-related serious adverse events and no neutropenia observed in dose level 1 and dose level 2 patient cohorts.

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Clinical Development Plan

The Phase 1a dose escalation portion of the trial is ongoing. We currently anticipate dose levels 3 and 4 to be clinically active doses, and we plan to provide additional clinical data in 2023.

STAT3 Degrader for Cancer and Autoimmune/Fibrotic Diseases

Summary

We are developing our selective STAT3 degraders for the treatment of hematological malignancies and solid tumors, as well as autoimmune diseases and fibrosis. STAT3 is a transcription factor activated through a variety of different cytokine and growth factor receptors via JAKs, as well as through oncogenic fusion proteins and mutations in STAT3 itself. We believe the diverse functions of STAT3 in tumor biology, evasion of immune surveillance by tumor cells, and inflammation and fibrosis provide opportunities to address a wide variety of high unmet need disease indications through the targeting of a single genetically and clinically validated pathway. While the JAK-STAT pathway has been partially addressed with several clinically successful JAK-targeting agents, we believe there are currently no drugs that specifically affect STAT3 broadly across all the relevant cell types. Small molecule STAT3 dimerization inhibitors targeting the SH2 domain have been in development, but significant challenges remain: first, homology of SH2 domains among all STAT family members impacts the ability to achieve specificity for STAT3, and second, inability to block dimerization independent transcriptional activities of STAT3. For these reasons, we believe that STAT3 degraders may provide a transformative solution to develop targeted and specific drugs to address multiple STAT3 dependent pathologies.

In September 2022, our STAT3 degrader, KT-333, was granted its second orphan drug designation by the FDA for the treatment of cutaneous T-cell lymphoma, following its orphan drug designation for peripheral T-cell lymphoma, earlier that year. We are currently evaluating KT-333 in a Phase 1 clinical trial in patients with relapsed/refractory liquid and solid tumors, including aggressive lymphomas. Patient enrollment and dosing are ongoing in the Phase 1a portion of the trial, and we expect to provide additional clinical data in 2023.

Biology and Mechanism of Action of STAT3 Degrader

STAT3 (signal transducer and activator of transcription 3) is a transcription factor and a member of the STAT protein family. In response to cytokines and growth factors, STAT3 is phosphorylated by receptor-associated serine/threonine kinases, and phosphorylated STAT3, or p-STAT3, then forms dimers that translocate into the nucleus, bind to DNA, and regulate transcription of a wide variety of genes involved in oncogenesis, inflammation and fibrosis. STAT3 is frequently mutated and activated in numerous cancers, including clinically aggressive hematologic malignancies with high unmet medical need. Mechanistically, aberrant activation of STAT3 has been directly linked to the promotion of cancer cell survival, proliferation, and metastasis. In addition, STAT3 regulates the crosstalk between tumor, stroma, and immune cells to promote an immunosuppressive tumor microenvironment. STAT3 activation by IL-6 and TGF-ß is also involved in the pathogenesis of autoimmunity and fibrosis. These various roles of STAT3 in disease pathogenesis make it an attractive target for drug development in cancer and autoimmune and fibrotic diseases.

Differentiation from JAK and IL-6 Inhibitors

Small molecule inhibitors against JAK family kinases, such as JAK1, JAK2, JAK3, and TYK2, have been approved for the treatment of autoimmune diseases such as RA, psoriatic arthritis, and ulcerative colitis and target the JAK2/STAT5 pathway. In oncology, JAK inhibitors have been approved for hematological malignancies with mutations leading to activation of the JAK2/STAT5 pathway, including primary myelofibrosis and polycythemia vera, and for acute graft versus host disease. JAK inhibitors block signaling of a number of cytokines and growth factors and reduce activation not only of STAT3 but also STAT1 and STAT5 in response to these stimuli. For modulating anti-tumor effects, this broad activity may have conflicting consequences. In particular, the inhibition of STAT1 activity dampens anti-tumor immune responses by cytolytic T cells and antigen presenting cells, thereby counteracting a productive immune response that could be achieved by inhibition of STAT3 alone. As a result, JAK inhibitors have not shown clinical activity in cancer beyond the myeloproliferative neoplasms. The broad activity of JAK inhibitors is also associated with class-specific adverse effects. By targeting STAT3 selectively, these immunosuppressive and safety liabilities associated with broader STAT1 and STAT5 inhibition through JAK inhibition may be avoided while also effectively addressing JAK-dependent and independent activation of STAT3.

Monoclonal antibodies directed against pro-inflammatory cytokines such as IL-6 or their receptors IL-6R have also been approved for select autoimmune diseases. However, autoimmune and fibrotic diseases and certain cancers are often regulated

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by multiple cytokines. As such, targeting STAT3 has the potential to be more effective since it is involved in signaling by not just IL-6, but also by TGF-ß and cytokines such as IL-12, IL-2 and IL-15. Consequently, targeting STAT3 directly has the potential to block multiple signaling pathways that converge on STAT3 and reverse pathological processes that contribute to a tumor-permissive microenvironment.

Development Opportunities

The multiple effects of a STAT3 degrader on oncogenesis, tumor cell resistance to tyrosine kinase inhibitors and chemotherapy, and evasion of immune surveillance provide multiple development opportunities in hematologic malignancies and solid tumors. Additionally, the role of STAT3 in chronic inflammation and fibrosis, as also observed in patients with germline STAT3 gain-of-function mutations, informs opportunities in autoimmune and fibrotic diseases.

Hematologic Malignancies

Oncogenic STAT3 mutations and/or STAT3 pathway activations are highly common in peripheral T-cell lymphoma, or PTCL and cutaneous T-cell lymphoma, or CTCL. PTCL has an estimated prevalence of approximately 40,000 patients in the major global markets and CTCL has an estimated prevalence of approximately 100,000 patients across the major global markets. STAT3 mutations and pathway activations along with responsiveness of PTCL subsets and CTCL to immune checkpoint inhibitors point to a dependency on STAT3 in these indications and therefore the opportunity to develop a STAT3 degrader as a monotherapy. The standard of care for first-line treatment of PTCL is the combination of brentuximab vedotin, a CD30-directed antibody-drug conjugate, and chemotherapy. The majority of PTCL patients, including ALK-ALCL, PTCL-Not Otherwise Specified, AITL and NK/T lymphoma subtypes, eventually progress and die of their disease. For patients with refractory/relapsed disease, current treatment options are limited and approved therapies pralatrexate and romidepsin have shown limited efficacy. High prevalence of STAT3 mutations (approximately 13-38%) and STAT3 pathway activation (up to 90%) is found in these refractory/relapsed PTCL subsets with high unmet need. Given the documented effect of STAT3 downregulation on levels of programmed death-ligand 1, or PD-L1, we expect our STAT3 degrader to have a dual effect in these patients. In CTCL patients with advanced stage disease and the highest levels of STAT3 activation, there are no curative therapies and no standard of care. Antibody-drug conjugates, HDAC inhibitors, and immune checkpoint inhibitors have some activity and are used upfront or in refractory/relapsed patients, but there remains a high unmet need for an effective therapeutic with both tumor-intrinsic as well as immunomodulatory antitumor effects.

STAT3 pathway activation is also present in virtually all patients with T- and NK-cell large granular lymphocytic leukemia, and up to 70% of patients have oncogenic STAT3 mutations. These findings are highly indicative of STAT3 dependency, which is further supported by the preliminary clinical activity of JAK inhibitors in these patients. STAT3 activation is also commonly observed in AML and in DLBCL even though STAT3 mutations are infrequent. PD-L1 overexpression in DLBCL has been linked to worse disease outcomes and responses to anti-PD-1/PD-L1 drugs have been reported in these patients. Given STAT3 has downstream impact on PD-1/PD-L1, we believe that a STAT3 degrader has the potential to achieve profound clinical effects both as a monotherapy and in combination with other active drugs.

Solid Tumors

Cancers that are responsive to anti-PD-1/PD-L1 immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs), including non-small cell lung cancer, or NSCLC, head and neck squamous cell carcinoma, or HNSCC, breast cancer and colorectal cancer, are compelling development opportunities due to the established role of STAT3 in solid tumor resistance to ICIs and TKIs. Specifically, STAT3 degraders have the potential to improve responses upfront in combination with these modalities or overcome acquired resistance as add-on therapy in second line.

Autoimmune and Fibrotic Diseases

Patients with rare germline STAT3 gain-of-function mutations develop multiple autoimmune and fibrotic diseases, including systemic sclerosis, or SSc, AD, interstitial lung disease, enteropathies, and RA. We believe these manifestations, and their response to JAK inhibitors, provide support for STAT3 degrader development in immunology and inflammation. There are numerous publications that highlight the role of STAT3-mediated IL-6 and TGF-ß signaling in the pathogenesis of SSc, idiopathic pulmonary fibrosis, or IPF, Crohn’s disease, and multiple sclerosis. There remains a high unmet need for drugs that can target both the inflammation and fibrosis in SSc, IPF and other diseases that cause Progressive Fibrosing Interstitial Lung Disease (PF-ILD) and halt or reverse disease progression. A STAT3 degrader has the potential for this dual effect and could therefore provide a transformative approach to treating PF-ILD as well as Crohn’s disease and RA.

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Preclinical Studies and Data

Figure 34 shows the selectivity of our STAT3 degrader as evidenced by proteomic analysis demonstrating that at KT-333 concentrations 10-fold greater than the DC95, STAT3 is the only protein to be degraded among over 10,000 proteins evaluated including other closely related STAT family members.

Figure 34. Change in Protein Levels

The in vivo activity of KT-333 is summarized in Figure 35, which shows weekly administration resulting in robust antitumor activity with full regressions that are durable in animals bearing STAT3-dependent T cell lymphomas. These regressions were associated with >90% STAT3 knockdown in tumors.

Figure 35. KT-333 In vivo activity

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While KT-333 single agent leads to profound anti-tumor activity, based on the role of STAT3 in the tumor microenvironment, additional studies were undertaken to explore the potential immune effects of STAT3 degraders on tumors. Figure 36 summarizes results from a mouse syngeneic colorectal cancer model, in which a STAT3 degrader resulted in an IFN-gamma-dependent gene expression signature that has previously been identified as a predictor of response in cancer patients treated with pembrolizumab. These findings are consistent with STAT3’s role in remodeling the tumor microenvironment and provide the rationale for combining STAT3 degraders with immune checkpoint inhibitors.

Figure 36. Mouse Syngeneic Colorectal Cancer Model

As shown in Figure 37, a mouse syngeneic CT-26 colorectal cancer model, the addition of KT-333 augmented the activity of a PD-1 inhibitor in a syngeneic mouse model of colorectal cancer (CT-26), resulting in complete regressions in a majority of animals. Furthermore, in the combination group, there was no tumor growth when re-challenged one month after last dose, suggesting development of long-term immune memory. In addition to causing tumor regressions, the combination extended survival relative to either PD-1 inhibitor or STAT3 degrader alone. Collectively, we believe these data suggest that the addition of STAT3 degraders could significantly augment the clinical efficacy of immune checkpoint inhibitors.

Figure 37. STAT3 Degradation and Anti-PD-1 Synergy

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Clinical Studies and Data

In 2022, we initiated our Phase 1 clinical trial of KT-333 to evaluate the safety, tolerability, PK/PD and clinical activity of KT-333 dosed weekly on Days 1, 8 and 15 of 28-day cycles in adult patients with relapsed and/or refractory lymphomas, leukemias and solid tumors. Figure 38 below shows the details of the trial.

Figure 38: KT-333 Phase 1 Clinical Trial Design

In December 2022 we announced that dose level 1 (0.05 mg/kg) had been completed with a total of four patients enrolled. All patients were heavily pretreated with multiple prior lines of therapy and included three patients with solid tumors and one patient with cutaneous T-cell lymphoma. As summarized in Figure 39, plasma PK and PD translated as we expected in humans with mean maximum STAT3 degradation in PBMC following the first 2 doses averaging 66%, with maximum STAT3 knockdown of up to 86% as measured by mass spectrometry.

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Figure 39: Clinical Pharmacodynamics in Peripheral Blood Mononuclear Cells by Mass Spectrometry

There were no dose limiting toxicities or treatment-related serious adverse events observed in dose level 1.

Clinical Development Plans

The Phase 1a dose escalation portion of the trial is ongoing. We currently anticipate dose levels 3 and 4 to be clinically active doses, and we expect to provide additional clinical data in 2023.

Preclinical Studies and Data in Autoimmunity

The following figures summarize the results of multiple preclinical experiments demonstrating robust antifibrotic and anti-inflammatory activity of STAT3 degraders in mouse models of systemic scleroderma, arthritis, and CNS inflammation. In the Tight Skin model, shown in Figure 40, a spontaneous TGF beta dependent model of fibrosis that is representative of scleroderma, STAT3 degradation resulted in significant reduction in skin thickening and completely inhibited myofibroblast contraction in an in vitro gel contraction assay.

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Figure 40. In Vivo tight Skin Model (Fibrosis)

In the Collagen Induced Arthritis (CIA) model, which is a prototypical model of RA, as shown in Figure 41, STAT3 degradation reduced the clinical signs of disease in a dose dependent manner. The effect of STAT3 degrader is also reflected by the significant reduction in pathology scores and periosteal bone growth.

Figure 41. In Vivo CIA Model (RA)

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Figure 42 illustrates the effect of STAT3 degradation in the Experimental Autoimmune Encephalomyelitis (or EAE) model representative of MS. In this model STAT3 degradation not only had a profound effect on severity of disease but also greatly reduced the incidence of disease and delayed onset of encephalomyelitis in the animals.

Figure 42. In Vivo MS Model

Collectively, these findings highlight the pleiotropic effects of STAT3 degraders in fibrosis and inflammation, demonstrating the potential for this approach across a broad spectrum of autoimmune diseases.

MDM2

Summary

We are developing degraders that target MDM2 for the treatment of solid tumors and hematological malignancies. MDM2 is the crucial regulator of the most common tumor suppressor, p53, which remains intact (or wild type) in more than 50% of cancers. Unlike small molecule inhibitors, our MDM2 degrader, KT-253, has been shown preclinically to have the ability to overcome the MDM2 feedback loop and rapidly induce apoptosis, even with brief exposures. In December 2022, we announced that we received clearance from the FDA for our IND for KT-253. We plan to initiate a Phase 1 clinical trial of KT-253 in early 2023, which is designed to evaluate the safety, tolerability, PK/PD and clinical activity of KT-253 in adult patients with liquid and solid tumors.

Target Rational and Mechanism of Action

MDM2 is the major E3 ligase which controls the tumor suppressor p53. p53 is functional in close to 50% of cancers, both liquid and solid, and many p53 functional cell lines are dependent on MDM2 overexpression for p53 suppression and survival. Stabilization and upregulation of p53 by removal of MDM2 by degradation can cause cells to undergo cell death and/or cell cycle arrest. While MDM2 small molecule inhibitors have shown clinical activity in a variety of tumor types, the activity has been limited as a result of the inhibition of MDM2 leading to a feedback loop, as shown in Figure 43. This feedback loop results in upregulation of MDM2 protein expression, which in turn makes it more difficult for occupancy-driven small molecules to inhibit MDM2. As a result, small molecule inhibitors have had a more modest effect on p53 upregulation which often leads to cell cycle arrest rather than apoptosis, thereby limiting the efficacy of MDM2/p53 small molecule inhibitors. This feedback loop also necessitates more chronic exposure to drug to maintain modest MDM2 inhibition in tumors, potentially leading to toxic effects on normal cells that limits the safety and tolerability of these inhibitors. Degraders have the potential to overcome the MDM2 feedback loop by completely removing the protein in a catalytic manner. This enables the development of highly potent drugs that are able to induce strong p53 upregulation and an irreversible acute apoptotic response in tumor cells with just brief exposures, thereby maximizing efficacy and improving the safety profile by allowing time for the recovery of normal cells.

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Figure 43. MDM2 Feedback Loop

Preclinical Data

KT-253 is designed as a potent and selective degrader of MDM2. Figure 44 displays the sub-nanomolar potency of KT-253 as compared to a small molecule inhibitor currently in clinical trials.

Figure 44. KT-253 Sub-nanomolar Potency

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We observed increased p53 stabilization over small molecule inhibitors, as shown in Figure 45.

Figure 45. p53 Stabilization

As a result, we believe KT-253 has potential to have stark potency differences versus the inhibitors in cell killing assays in p53 wild type Acute Lymphocytic Leukemia, as shown in Figure 46.

Figure 46. Tumor cell killing (pM range)

As shown in Figure 47, KT-253 is 200-fold more potent in the RS4-11 Acute Lymphocytic Leukemia cell line compared to what has been published, to date, on the most potent MDM2 small molecule in the clinic (DS-3032).

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Figure 47. KT-253 Potency in the RS4-11 Acute Lymphocytic Leukemia cell line

We believe the potency of KT-253 relative to a MDM2 small molecule inhibitor is the result of its ability to overcome the feedback up-regulation of MDM2, as shown below in Figure 48.

Figure 48. Degrader Overcomes MDM2 Feedback Loop

Figure 49 illustrates that with a single low dose at 1mg/kg, KT-253 induces PD markers of MDM2 inhibition, including brisk p53 upregulation and acute apoptotic readouts such as PUMA. This single low dose sends the established tumor model into deep regression for weeks, while also allowing time for recovery of any normal cells affected. Clinically equivalent exposures of small molecules have not been observed to have significant in vivo activity in this xenograft model.

Figure 49. KT-253 PD markers

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Figure 50 shows that a single dose of KT-253 at 1mg/kg, Q3W achieves in vivo tumor regression in the CTG-2227 AML patient-derived xenograft (PDX) model as measured by reduction of human CD45+ cells in the bone marrow and AML blats in whole blood.

Figure 50. KT-253 In Vivo tumor regression

Figure 51 shows that KT-253 administered once every three weeks in combination with the AML standard of care agent, venetoclax, was more active than either compound alone in the MOLM13 AML CDX model, resulting in sustained tumor regression.

Figure 51. Strong Single Agent and Combinatorial Activity
in Venetoclax Resistant AML Models

 

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Figure 52 illustrates MDM2 dependency is seen across a large subset of tumor types as shown on the left by genetically knocking out MDM2 across a panel of cell lines and on the right, showing effects on cell lines by pharmacologically removing MDM2 with a degrader. KT-253 shows marked superiority over the SMI DS-3032 in the panel of Acute Lymphocytic Leukemia (ALL), AML, DLBCL and Uveal melanoma cells.

Figure 52. MDM2 Dependency

Development Opportunities

The large numbers of p53wt cell lines dependent on MDM2, as depicted in Figure 52 above on the left blue, gives a high-level view of the potential breadth of opportunities in oncology for a potent and well tolerated agent for this pathway. These tumor cell types include but are not limited to cancers which have amplification and over expression of MDM2. De-stabilization of p53 by MDM2 enables cells to survive by blocking both cell cycle arrest and apoptosis. While the opportunities are very diverse, we plan to focus our development efforts on tumors which are most susceptible to the acute apoptotic response elicited by our degraders, where we believe we will be able to achieve the greatest therapeutic index and efficacy. Our initial disease areas of interest are AML, Uveal melanoma and lymphomas, in addition to other solid tumors indications where preclinically we see that MDM2 degradation leads to an acute apoptotic response predictive of clinical activity with intermittent dosing.

Clinical Development Plans

In December 2022, we announced we received FDA clearance of our IND to evaluate KT-253 and we expect to initiate our Phase 1 trial in solid tumors and hematologic malignancies in early 2023. We have identified AML as an initial hematologic indication for development based on strong pre-clinical KT-253 activity. Preclinical data also support potential development in other hematologic indications, such as ALL and NHL, as well as in select sensitive solid tumors.

Our PegasusTM Platform

Our proprietary drug discovery platform, PegasusTM, enables us to rationally design targeted protein degraders that have the potential to drug all target classes in the cell. Our approach is rooted in an understanding of the relationship between E3 ubiquitin ligases and target proteins, which allows us to identify the properties that make a target both ligandable and degradable, and determine how multiple factors impact potency, selectivity, PK and PD. Key components of our platform include our E3 ligase toolbox, our understanding of degradation across healthy and diseased tissue types, our proprietary chemistry and our Center for Molecular Glue Discovery.

We have developed a proprietary human whole body E3 Atlas for mapping expression patterns of all known human E3 ubiquitin ligases in both healthy and disease contexts by combining the power of quantitative, high-resolution proteomics with proprietary algorithms. We are refining the characterization of the expression profiles in healthy and diseased tissues of well-established liganded E3 ligases such as cereblon and VHL and, more importantly, of other naturally occurring E3 ligases, which remain unliganded to date. We have established subcellular localization indices for each E3 ligase and are determining their

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absolute abundances. We believe our approach is designed to overcome the limitations of relying on publicly available RNA or antibody-based protein expression datasets, which often lead to inaccuracies in determining relative E3 ligase expression levels in different biological contexts.

Our proprietary E3 Ligase Whole-Body Atlas enables data-driven, disease-selective protein degradation strategies based on all of the mapped E3 ligases, which we view as a paradigm shift from relying on the limited number of E3 ligases typically exploited for TPD and provides us with a distinct competitive advantage. Using comparative analyses of expression patterns, we can identify selective pairings of E3 ubiquitin ligases with therapeutic targets of interest, including tissue-selective or tissue-restrictive pairings. We believe this approach is central to building out a toolbox of differentiated E3 ubiquitin ligase binders. Furthermore, we are able to use our custom-built Quantitative Systems Pharmacology Models in combination with proprietary data to understand the absolute abundance of E3 ligases and protein targets to predict cellular efficacy. Figure 53 below shows an example of diverse expression profiles, using circle size as a relative abundance measure, for E3 ligases and selected targets across a panel of healthy tissues (on the x-axis), taken from our proprietary E3 Ligase Whole-Body Atlas.

Figure 53. Novel E3 Ligases to Drug a New Generation of Targets

As an example of our work in this area, we have identified a tissue-selective E3 ubiquitin ligase that we believe, based on a comprehensive analysis using both proteomics and transcriptomics, is localized to a specific cell type, our target cell, and is not expressed in several other cell types. We believe this profile may allow for the selective degradation of a protein only in our target cells. We have fully characterized this novel tissue selective ligase and, through hit-finding campaigns, have identified unique chemical matter which has affinity for this E3 ligase below 1 uM. We have also shown productive ternary complex formation against the identified therapeutic target. Figure 54 illustrates, on the left, the tissue-selective expression of the E3 ligase and, on the right, the binding affinity of the lead compound and ternary complex formation with the target protein of interest.

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Figure 54. Tissue-selective expression and binding affinity

We are also developing targeted protein degraders directed against a well-validated and high-value oncology target that has known on-target heme toxicity. Utilizing our discovery platform, we have identified an E3 ligase that has very low expression in the target cell responsible for this toxicity, as illustrated in Figure 55 below in the Western Blot analysis.

Figure 55. Western Blot analysis

We have developed novel degraders for this oncology target that have demonstrated potent degradation of target type, as shown in the top panel of Figure 56. As illustrated in the middle panel, we have also shown that our degrader does not degrade

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the target in the key blood cell type. Additionally, as shown in the bottom panel, when comparing this novel degrader, versus a well-known small molecule inhibitor, we were able to show that the degrader allows these blood cells to survive while the small molecule inhibitor led to substantial cell death. This is the first in vivo proof-of-concept of selectively degrading this target while avoiding known on target heme toxicity, which we believe is a significant advance that demonstrates the capabilities of our platform.

Figure 56. Degrader profile

As illustrated below in Figure 57, we utilize a broad range of hit finding approaches to develop small molecules against our selected targets. Specifically, we use virtual screening and artificial intelligence enabled iteration to characterize the binding pocket of target proteins and E3 ligases, to evaluate ligandability and to find small molecule ligands. We also use high content screening such as DNA-encoded libraries (DEL), Affinity Selection Mass Spectrometry (ASMS) or traditional high throughput screening (HTS). We use Fragment Based Screening (FBS) and covalent screening for more targeted approaches where protein topology is understood. We also utilize X-ray and cryoEM capabilities to enable not only hit finding, but also ternary complex optimization.

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Figure 57. Hit finding approaches

As illustrated in Figure 58 below, our proprietary chemistry approach utilizes ternary complex modelling, which leverages cloud computing to evaluate millions of compounds with the objective to design both an optimal linker and to identify the correct vectors to enable efficient binding of both an E3 ligase ligand and protein ligand. We use molecular chameleonicity to accurately design and predict ADME and PK profiles of these complex molecules which is critical to designing molecules with high oral bioavailability. Our experienced chemistry and computational chemistry teams utilize artificial intelligence driven insights to understand those design parameters driving clearance, permeability and efflux.

Figure 58. Proprietary chemistry approach

We also utilize a mechanistic modelling process to predict accurately both human PK and PD from preclinical data, an example of which is illustrated in Figure 59. We first applied an indirect PK/PD response model to describe the mechanism of action of TPD. We then accounted for the biodistribution of drug to target tissue and used an Emax exposure-response model to describe the mechanism of action of TPD. A preclinical PK/PD study was conducted in dog to understand the kinetics of protein degradation in tissues at different dose levels, with data used to estimate in vivo degradation potency and protein turnover rate in the target tissue. We then “humanize” the PK/PD model by applying human PK parameters, adjusting for species’ differences in potency and protein turnover rate, if necessary, to predict protein degradation in the clinic. As shown in the far right of Figure 59, the model accurately predicted human PD, as measured by predicted IRAK4 reduction, using preclinical PK/PD animal data (orange) to predict human PK/PD data in (blue).

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Figure 59. Modeling Approach

Our Center for Molecular Glue Discovery is focused on identifying novel E3 ligases, beyond cereblon, that enable the design of molecules that target undrugged and un-ligandable proteins through small molecule interactions. Molecular glues, rather than requiring a defined binding pocket on the undruggable target, leverage a weak preexisting interaction between an E3 ligase and an unligandable protein of interest. Through binding of the molecular glue to the E3 ligase, the protein-protein interaction interface of the E3 ligase is remodeled, leading to enhanced interaction of the two proteins, thus facilitating degradation. Our approach is to move beyond the traditional approach of molecular glues, which mostly utilize cereblon/IMiD based molecular glues. We have established strategic partnerships to advance our molecular glue initiatives. Our work with these groups is focused on identifying and characterizing novel E3 ligase/substrate pairs for molecular glue interactions that exploit natural affinity augmented with small molecules. We are utilizing genetic screening, structural insights, and pathway and computational biology to identify novel matched pairs of E3 ligases and high value undrugged targets.

We recently announced the discovery of a novel degron interaction for a target that we believe is undrugged and not ligandable. This finding has led to the identification and characterization of a highly selective novel molecular glue of an ‘undruggable’ transcription factor, and to the initiation of multiple molecular glue discovery programs.

Other Programs

Our focus on key undrugged or inadequately drugged nodes within therapeutically validated pathways combined with the target and disease agnostic features of our PegasusTM platform gives us opportunity to develop new therapies across various therapeutic areas. We are taking advantage of our proprietary E3 Ligase Whole-Body Atlas on the differential expression profile of E3 ligases to pursue targets that can benefit from potentially tissue-restricted degradation as well as programs that can be enabled by novel molecular glue mechanisms. Our early pipeline includes programs in genetically defined oncology and immunology indications. Through our Vertex collaboration, we are engaged in the discovery of additional targets that are able to fully leverage our aforementioned capabilities and expand our impact across several diseases outside of oncology and immunology.

Collaborations

Master Collaboration Agreement with Vertex Pharmaceuticals Incorporated

On May 9, 2019, we entered into a collaboration agreement with Vertex, focused on the research and development of our small molecule targeted protein degraders against multiple targets in disease areas outside our core strategic focus. The collaboration leverages our expertise in targeted protein degradation and our PegasusTM platform as well as Vertex’s scientific, clinical, and regulatory capabilities to accelerate the development of medicines for people with serious diseases. We refer to this agreement as the Vertex Agreement.

Under the terms of the Vertex Agreement, we conduct research activities in multiple targets pursuant to an agreed-upon research plan. Upon designation of a clinical development candidate, Vertex has the option to exclusively license molecules against the designated target. We are eligible to receive an aggregate of up to $170 million in potential payments per licensing product based upon the successful achievement of specified research, development, regulatory and commercial milestones, as

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well as option exercise payments, for up to six (6) programs optioned by Vertex for licensing as part of the collaboration. No milestones have been achieved to date under the Vertex Agreement.

In addition, Vertex will pay low single-digit royalties on future net sales on any products that may result from the commercialization of the licensed molecules. Vertex’s royalty obligations are on a product-by-product and country-by-country basis and are subject to certain reductions, including (i) in the event that the exploitation of a product is not covered by a valid claim with the licensed patent rights and (ii) in the event of third parties achieving specifically negotiated levels of competitive market share. Such royalty obligations will expire on a country-by-country and product-by-product basis upon the later of (a) the expiration of the last patent which covers a product in such country, (b) the expiration of any exclusivity granted by a regulatory authority and (c) 10 years following the first commercial sale of a product in such country. No additional payments have been made by Vertex under the Vertex Agreement to date.

As initial consideration for the collaboration, Vertex paid us $70 million upfront including an equity investment in us through the purchase of 3,059,695 shares of our Series B-1 preferred stock.

Under the Vertex Agreement, the parties established a joint advisory committee, or JAC. The JAC will, among other responsibilities, review and oversee, certain strategic activities performed under the Vertex Agreement, including reviewing the research plan and budget for the research activities and reviewing the research activities performed by each party.

The initial research term of the collaboration is four years, extendable for an additional one-year period upon mutual agreement by the parties and payment by Vertex of certain per-target fees.

The Vertex Agreement may be terminated by Vertex either in its entirety or on a target-by-target basis, upon prior written notice to Kymera. Either party may terminate the collaboration agreement upon the other party’s material breach, subject to specified notice and cure provisions, or upon the bankruptcy, insolvency, dissolution or winding up of the other party. Kymera also has the right to terminate the agreement with respect to a certain target upon 30 days’ prior written notice in the event that Vertex ceases all research, development and commercialization activities related to such target for a certain period of time, provided that the cessation is not the result of events outside of Vertex’s control.

Collaboration Agreement with Genzyme Corporation

On July 7, 2020, we entered into a collaboration agreement, or the Original Sanofi Agreement, with Genzyme Corporation, a subsidiary of Sanofi, to co-develop drug candidates directed to two biological targets. The Original Sanofi Agreement became effective during the third quarter of 2020.

On November 15, 2022, we entered into an Amended and Restated Collaboration and License Agreement with Sanofi, or the Amended Sanofi Agreement, which amended the Original Sanofi Agreement to revise certain research terms and responsibilities set forth under the Original Sanofi Agreement. The Amended Sanofi Agreement also specifies details around the timing and number of Phase 2 trials required under the terms of the collaboration. The Amended Sanofi Agreement became effective on December 5, 2022. The Original Sanofi Agreement, as amended by the Amended Sanofi Agreement, is referred to herein as the Sanofi Agreement.

Under the Sanofi Agreement, Kymera grants to Sanofi a worldwide exclusive license to develop, manufacture and commercialize certain lead compounds generated during the collaboration directed against IRAK4 and one additional undisclosed target in an undisclosed field of use. Such license is exercisable on a collaboration target-by-collaboration target basis only after a specified milestone. For compounds directed against IRAK4, the field of use includes diagnosis, treatment, cure, mitigation or prevention of any diseases, disorders or conditions, excluding oncology and immune-oncology.

Pursuant to the Sanofi Agreement, with respect to both targets we are responsible for discovery and preclinical research and conducting a phase 1 clinical trial for at least one degrader directed against IRAK4 plus up to three back up degraders, the costs of which will be borne by us, except in certain circumstances. With respect to both targets, Sanofi is responsible for development, manufacturing, and commercialization of product candidates after a specified development milestone occurs with respect to each collaboration candidate.

In addition, pursuant to the Sanofi Agreement, Sanofi will grant to us an exclusive option, or Opt-In Right, exercisable, at our sole discretion, on a collaboration target-by-collaboration target basis that will include the right to (i) fund 50% of the United States development costs for collaboration products directed against such target in the applicable field of use and (ii) share equally in the net profits and net losses of commercializing collaboration products directed against such target in the applicable field of use in the United States. In addition, if we exercise our Opt-In Right, Sanofi will grant to us an exclusive

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option, applicable to each collaboration target, which upon exercise will allow us to conduct certain co-promotion activities in the field in the United States.

In consideration for the exclusive licenses granted to Sanofi under the Sanofi Agreement, Sanofi paid to us an upfront payment of $150.0 million. In addition to the upfront payment, we will also be eligible to receive certain development milestone payments of up to $1.48 billion in the aggregate, of which more than $1.0 billion relates to the IRAK4 program, upon the achievement of certain developmental or regulatory events. We will also be eligible to receive certain commercial milestone payments up to $700.0 million in the aggregate, of which $400.0 million relates to the IRAK4 program, which are payable upon the achievement of certain net sales thresholds. We will further be eligible to receive tiered royalties for each program on net sales ranging from the high single digits to high teens, subject to low-single digits upward adjustments in certain circumstances.

The Sanofi Agreement, unless earlier terminated, will expire on a product-by-product basis on the date of expiration of all payment obligations under the Sanofi Agreement with respect to such product. We or Sanofi may terminate the agreement upon the other party’s material breach or insolvency or for certain patent challenges. In addition, Sanofi may terminate the agreement for convenience or for a material safety event upon advance prior written notice, and we may terminate the agreement with respect to any collaboration candidate if, following Sanofi’s assumption of responsibility for the development, commercialization or manufacturing of collaboration candidates with respect to a particular target, Sanofi ceases to exploit any collaboration candidates directed to such target for a specified period.

Additionally, on December 2, 2022, Sanofi provided us with written notice of its intention to advance the collaboration target 1 candidate, KT-474, into Phase 2 clinical trials. We are entitled to receive milestone payments upon the dosing of the first patient(s) in Phase 2 studies per indication up to a specified number of indications as further set forth in the Sanofi Agreement.

Manufacturing / Supply Chain

We do not own or operate manufacturing facilities for the production of our drug candidates and currently have no plans to build our own clinical or commercial scale manufacturing capabilities. We currently engage with third-party contract manufacturing organizations, or CMOs, for the manufacture of our drug candidates for preclinical studies, and we intend to continue to do so in the future. We rely on and expect to continue to rely on third-party manufacturers for the production of both drug substance and finished drug product. We have engaged third-party manufacturers to supply the drug substances for our drug candidates and a third-party manufacturer to develop and manufacture finished drug products that we are using in our clinical trials. We currently obtain our supplies from these manufacturers on a purchase order basis and do not have long-term supply arrangements in place. Should any of these manufacturers become unavailable to us for any reason, we believe that there are a number of potential replacements, although we may incur some delay in identifying and qualifying such replacements.

All of our drug candidates are organic compounds of low molecular weight, generally called small molecules, but which are larger than traditional small molecule therapeutics. We have selected these compounds not only on the basis of their potential efficacy and safety, but also because we anticipate an ease of synthesis and cost of goods. We have produced drug substances and drug products for use in our clinical trials and continue to refine our production processes. The drug substance and drug product processes are amenable to scale-up and do not require unusual equipment in the manufacturing process. To adequately meet our needs for late-stage clinical and commercial manufacturing, our suppliers will need to scale their production, or we will need to secure alternate suppliers.

Competition

The biotechnology industry is extremely competitive in the race to develop new products. While we believe we have significant competitive advantages with our years of expertise in targeted protein degradation, clinical development expertise, and intellectual property position, we currently face and will continue to face competition for our development programs from companies that use targeted protein degradation or targeted protein degradation development platforms, and from companies focused on more traditional therapeutic modalities such as small molecules and antibodies. The competition is likely to come from multiple sources, including larger pharmaceutical companies, biotechnology companies, and academia.

Competitors in our efforts to develop small molecule protein degraders therapies for patients, include, but are not limited to, Arvinas, Inc., C4 Therapeutics, Inc., Nurix Therapeutics, Inc., and Foghorn Therapeutics, Inc. Further, several large pharmaceutical companies have disclosed preclinical investments in this field. Our competitors will also include companies that are or will be developing other targeted protein degradation methods as well as small molecule, antibody, or gene therapies

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for the same indications that we are targeting. In addition to the competitors we face in developing small molecule protein degraders, we will also face competition in the indications we expect to pursue with our IRAK4, IRAKIMiD, STAT3, and MDM2 programs. Many of these indications already have approved standards of care which may include more traditional therapeutic modalities. In order to compete effectively with these existing therapies, we will need to demonstrate that our protein degrader therapies are favorable to existing therapeutics.

Intellectual Property

Our success depends in part on our ability to secure intellectual property protection for our product candidates and future products, as well as our platform protein degradation technologies and any other relevant inventions and improvements that are considered commercially important to our business. Our success also depends on our ability to defend and enforce our intellectual property rights, preserve the confidentiality of our proprietary information, and operate without infringing, misappropriating or otherwise violating the valid and enforceable patents and proprietary rights of third parties.

As with other biotechnology and pharmaceutical companies, our ability to secure and maintain intellectual property protection for our product candidates, future products, and other proprietary technologies will depend on our success in obtaining effective patent coverage and enforcing those patents if granted. However, we cannot guarantee that our pending patent applications, and any patent applications that we may in the future file, will result in the issuance of patents, or that any issued patents we may obtain will provide sufficient proprietary protection from competitors. Any issued patents that we obtain may be challenged, invalidated, or circumvented by third parties.

In addition to patents, we also rely on trade secrets, know-how and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary technology, in part, through confidentiality agreements and invention assignment agreements with our employees, consultants, scientific advisors, contractors and potential collaborators.

Patent Portfolio

Our intellectual property includes a portfolio of wholly owned patent families covering our platform E3 ligase ligand technology and our novel bifunctional degrader product candidates, including claims to compositions of matter, pharmaceutical compositions, methods of use, methods of treatment, and other related compounds and methods. Our intellectual property portfolio is in its very early stages, and, as of January 20, 2023, included nine granted U.S. patents, about 101 U.S. patent applications, about 20 international patent applications, and about 259 foreign patent applications. Our patent portfolio is generally organized into two categories: (1) platform E3 ligase ligand patent families and (2) protein degrader patent families, including various target-specific degrader patent families.

Platform E3 Ligase Ligand Patent Families

Our platform E3 ligase ligand patent families are wholly owned and include four patent families directed to novel ligands for the cereblon E3 ubiquitin ligase, as well as methods of treatment and other related methods. As of January 20, 2023, our platform E3 ligase ligand patent families included three granted U.S. patents, four U.S. patent applications, and three patent applications in Europe. Any U.S. or foreign patents resulting from these applications, if granted and all appropriate maintenance fees paid, are expected to expire between 2038 and 2040, absent any patent term adjustments or extensions.

Protein Degrader Patent Families

Our protein degrader patent families are wholly owned and are directed to novel bifunctional degrader compounds that are useful in affecting ubiquitination of a target protein, as well as methods of treatment and other related methods. As of January 20, 2023, our protein degrader patent families included one granted U.S. patent, seven U.S. patent applications and about 14 foreign patent applications filed in foreign jurisdictions, such as Australia, Canada, Europe, Israel, Japan, Mexico, New Zealand, and the Russian Federation. Any U.S. or foreign patents resulting from these applications, if granted and all appropriate maintenance fees paid, are expected to expire between 2038 and 2043, absent any patent term adjustments or extensions.

Target-Specific Degrader Patent Families

Our target-specific degrader patent families are wholly owned and focus protection around degrader compounds that are designed to target specific proteins for degradation, as well as methods of treatment and other related methods. Such targets include, for example, IRAK (interleukin-1 receptor-associated kinases) and STAT (signal transducers and activators of transcription). As of January 20, 2023, our target-specific degrader patent families included five granted U.S. patents, about 84

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U.S. patent applications, about 20 international patent applications, and about 241 patent applications filed in foreign jurisdictions, such as Australia, Brazil, Canada, China, Eurasia, Europe, Israel, India, Japan, Mexico, New Zealand, Singapore, South Africa, and Taiwan. Any U.S. or foreign patents resulting from our target-specific degrader patent families, if granted and all appropriate maintenance fees paid, are expected to expire between 2038 and 2044, absent any patent term adjustments or extensions.

IRAK-Specific Patent Families

Our IRAK-specific patent families are wholly owned and include patent families covering degrader compounds that are designed to specifically target IRAK for degradation and patent families covering novel IRAK ligands. As of January 20, 2023, our IRAK-specific patent families included four granted U.S. patents, about 34 U.S. patent applications, about 9 international patent applications, and about 158 patent applications filed in foreign jurisdictions, such as Australia, Argentina, Brazil, Canada, China, Europe, Eurasia, Gulf Cooperation Council, Israel, India, Japan, Mexico, New Zealand, Singapore, South Africa, and Taiwan. Any U.S. or foreign patents resulting from our IRAK-specific patent families, if granted and all appropriate maintenance fees paid, are expected to expire between 2038 and 2044, absent any patent term adjustments or extensions.

With respect to the KT-474 product candidate, as of January 20, 2023, we own one granted U.S. patent, 15 pending U.S. patent applications, three pending international patent applications, and about 81 patent applications filed in foreign jurisdictions, such as Australia, Brazil, Canada, China, Europe, Israel, India, Japan, South Korea, Mexico, New Zealand, Singapore, South Africa, and Taiwan, each with claims directed to compositions of matter covering KT-474 and/or methods of making or using KT-474. Any U.S. or foreign patents resulting from these patent families, if granted and all appropriate maintenance fees paid, are expected to expire between 2039 and 2044, absent any patent term adjustments or extensions.

STAT-Specific Patent Families

Our STAT-specific patent families are wholly owned and focus on degrader compounds that are designed to specifically target signal transducers and activators of transcription (STAT) for degradation. As of January 20, 2023, our STAT-specific patent families included one granted U.S. patent, 14 U.S. patent applications, two international patent applications, and about 33 patent applications filed in foreign jurisdictions, such as Australia, Canada, China, Eurasia, Europe, India, Israel, Japan, South Korea, Mexico, and Taiwan. Any U.S. or foreign patents resulting from our STAT-specific patent families, if granted and all appropriate maintenance fees paid, are expected to expire between 2040 and 2044, absent any patent term adjustments or extensions.

Other Target-Specific Patent Families

As of January 20, 2023, we own about 36 U.S. patent applications, nine international patent applications and about 50 patent applications filed in Australia, Argentina, Brazil, Canada, China, Europe, Gulf Cooperation Council, Israel, India, Japan, Mexico, New Zealand, Singapore, South Africa, and Taiwan which focus on degrader compounds designed to specifically target other proteins. Any U.S. or foreign patents resulting from these patent families, if granted and all appropriate maintenance fees paid, are expected to expire between 2040 and 2044, absent any patent term adjustments or extensions.

The term of individual patents may vary based on the countries in which they are obtained. Generally, patents issued from applications filed in the United States are effective for 20 years from the earliest effective non-provisional filing date. In certain cases, a patent term can be extended to recapture a portion of the term effectively lost as a result of the FDA regulatory review period. The Hatch-Waxman Act permits a patent term extension of up to five years beyond the expiration of the patent, though the total patent term, including any extension, must not exceed 14 years following FDA approval. A patent can only be extended once, such that, if a single patent is applicable to multiple products, it can only be extended based on one product.

The duration of patents outside of the United States varies in accordance with provisions of applicable local law, but typically is also 20 years from the earliest effective national filing date.

Similar patent term extension provisions are available in Europe and other foreign jurisdictions to extend the term of a patent covering an approved drug. When possible, we expect to apply for patent term extensions for patents covering our product candidates and their methods of use.

Trademarks

We intend to file applications for trademark registrations in connection with our product candidates and other technologies in various jurisdictions, including the United States.

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We have applied to register both the KYMERA mark and the KYMERA THERAPEUTICS mark in the United States, Europe, and Canada. We also filed applications in the same jurisdictions for the mark IRAKIMiD, for pharmaceutical and medical preparations and therapeutics, as well as diagnostic reagents, for the treatment of oncology, autoimmune, immune-oncology and other related diseases. In addition, we filed applications for E3 HUMAN ATLAS and E3 LIGASE WHOLE BODY ATLAS in connection with pharmaceutical research and development and drug development and discovery services. All of our European Union trademarks in existence as of December 31, 2020 were automatically cloned onto the United Kingdom register due to “Brexit.”

Most recently, we filed an application for our K & Design mark in the United States, and we plan to file European Union, United Kingdom, and Canada applications based on our U.S. priority date in that application in due course.

Government Regulation

The FDA and other regulatory authorities at federal, state and local levels, as well as in foreign countries, extensively regulate, among other things, the research, development, testing, manufacture, quality control, import, export, safety, effectiveness, labeling, packaging, storage, distribution, record keeping, approval, advertising, promotion, marketing, post-approval monitoring and post-approval reporting of drugs. We, along with our vendors, contract research organizations and contract manufacturers, will be required to navigate the various preclinical, clinical, manufacturing and commercial approval requirements of the governing regulatory agencies of the countries in which we wish to conduct studies or seek approval of our product candidates. The process of obtaining regulatory approvals of drugs and ensuring subsequent compliance with appropriate federal, state, local and foreign statutes and regulations requires the expenditure of substantial time and financial resources.

In the U.S., the FDA regulates drug products under the Federal Food, Drug, and Cosmetic Act, or FD&C Act, as amended, its implementing regulations and other laws. If we fail to comply with applicable FDA or other requirements at any time with respect to product development, clinical testing, approval or any other legal requirements relating to product manufacture, processing, handling, storage, quality control, safety, marketing, advertising, promotion, packaging, labeling, export, import, distribution, or sale, we may become subject to administrative or judicial sanctions or other legal consequences. These sanctions or consequences could include, among other things, the FDA’s refusal to approve pending applications, issuance of clinical holds for ongoing studies, suspension or revocation of approved applications, warning or untitled letters, product withdrawals or recalls, product seizures, relabeling or repackaging, total or partial suspensions of manufacturing or distribution, injunctions, fines, civil penalties or criminal prosecution.

The process required by the FDA before our product candidates are approved as drugs for therapeutic indications and may be marketed in the U.S. generally involves the following:

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Preclinical Studies and Clinical Trials for Drugs

Before testing any drug in humans, the product candidate must undergo rigorous preclinical testing. Preclinical studies include laboratory evaluations of drug chemistry, formulation and stability, as well as in vitro and animal studies to assess safety and in some cases to establish the rationale for therapeutic use. The conduct of preclinical studies is subject to federal and state regulations and requirements, including GLP requirements for safety/toxicology studies. The results of the preclinical studies, together with manufacturing information and analytical data must be submitted to the FDA as part of an IND. An IND is a request for authorization from the FDA to administer an investigational product to humans and must become effective before clinical trials may begin. Some long-term preclinical testing may continue after the IND is submitted. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, raises concerns or questions about the conduct of the clinical trial, including concerns that human research patients will be exposed to unreasonable health risks, and imposes a full or partial clinical hold. FDA must notify the sponsor of the grounds for the hold and any identified deficiencies must be resolved before the clinical trial can begin. Submission of an IND may result in the FDA not allowing clinical trials to commence or not allowing clinical trials to commence on the terms originally specified in the IND.

The clinical stage of development involves the administration of the product candidate to healthy volunteers or patients under the supervision of qualified investigators, generally physicians not employed by or under the trial sponsor’s control, in accordance with GCP requirements, which include the requirements that all research patients provide their informed consent for their participation in any clinical trial. Clinical trials are conducted under protocols detailing, among other things, the objectives of the clinical trial, dosing procedures, subject selection and exclusion criteria and the parameters and criteria to be used in monitoring safety and evaluating effectiveness. Each protocol, and any subsequent amendments to the protocol, must be submitted to the FDA as part of the IND. Furthermore, each clinical trial must be reviewed and approved by an IRB for each institution at which the clinical trial will be conducted to ensure that the risks to individuals participating in the clinical trials are minimized and are reasonable related to the anticipated benefits. The IRB also approves the informed consent form that must be provided to each clinical trial subject or his or her legal representative and must monitor the clinical trial until completed. The FDA, the IRB or the sponsor may suspend or discontinue a clinical trial at any time on various grounds, including a finding that the patients are being exposed to an unacceptable health risk. There also are requirements governing the reporting of ongoing clinical trials and completed clinical trials to public registries. Information about applicable clinical trials, including clinical trial results, must be submitted within specific timeframes for publication on the www.clinicaltrials.gov website.

A sponsor who wishes to conduct a clinical trial outside of the United States may, but need not, obtain FDA authorization to conduct the clinical trial under an IND. If a foreign clinical trial is not conducted under an IND, FDA will nevertheless accept the results of the study in support of an NDA if the study was conducted in accordance with GCP requirements, and the FDA is able to validate the data through an onsite inspection if deemed necessary.

Clinical trials to evaluate therapeutic indications to support NDAs for marketing approval are typically conducted in three sequential phases, which may overlap.

In March 2022, the FDA released a final guidance entitled “Expansion Cohorts: Use in First-In-Human Clinical Trials to Expedite Development of Oncology Drugs and Biologics,” which outlines how drug developers can utilize an adaptive trial design commonly referred to as a seamless trial design in early stages of oncology drug development (i.e., the first-in-human clinical trial) to compress the traditional three phases of trials into one continuous trial called an expansion cohort trial.

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Information to support the design of individual expansion cohorts are included in IND applications and assessed by FDA. Expansion cohort trials can potentially bring efficiency to drug development and reduce development costs and time.

Post-approval trials, sometimes referred to as Phase 4 clinical trials or post-marketing studies, may be conducted after initial marketing approval. These trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication and are commonly intended to generate additional safety data regarding use of the product in a clinical setting. In certain instances, the FDA may mandate the performance of Phase 4 clinical trials as a condition of approval of an NDA.

Progress reports detailing the results of the clinical trials, among other information, must be submitted at least annually to the FDA. Written IND safety reports must be submitted to the FDA and the investigators fifteen days after the trial sponsor determines the information qualifies for reporting for serious and unexpected suspected adverse events, findings from other studies or animal or in vitro testing that suggest a significant risk for human volunteers and any clinically important increase in the rate of a serious suspected adverse reaction over that listed in the protocol or investigator brochure. The sponsor must also notify the FDA of any unexpected fatal or life-threatening suspected adverse reaction as soon as possible but in no case later than seven calendar days after the sponsor’s initial receipt of the information.

Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the product candidate and finalize a process for manufacturing the drug product in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the product candidate and manufacturers must develop, among other things, methods for testing the identity, strength, quality and purity of the final drug product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the product candidate does not undergo unacceptable deterioration over its shelf life.

U.S. Marketing Approval for Drugs

Assuming successful completion of the required clinical testing, the results of the preclinical studies and clinical trials, together with detailed information relating to the product’s chemistry, manufacture, controls and proposed labeling, among other things, are submitted to the FDA as part of an NDA requesting approval to market the product for one or more indications. An NDA is a request for approval to market a new drug for one or more specified indications and must contain proof of the drug’s safety and efficacy for the requested indications. The marketing application is required to include both negative and ambiguous results of preclinical studies and clinical trials, as well as positive findings. Data may come from company-sponsored clinical trials intended to test the safety and efficacy of a product’s use or from a number of alternative sources, including studies initiated by investigators. To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety and efficacy of the investigational product to the satisfaction of the FDA. FDA approval of an NDA must be obtained before a drug may be marketed in the U.S.

The FDA reviews all submitted NDAs before it accepts them for filing and may request additional information rather than accepting the NDA for filing. The FDA must make a decision on accepting an NDA for filing within 60 days of receipt, and such decision could include a refusal to file by the FDA. Once the submission is accepted for filing, the FDA begins an in-depth substantive review of the NDA. The FDA reviews an NDA to determine, among other things, whether the drug is safe and effective for the indications sought and whether the facility in which it is manufactured, processed, packaged or held meets standards designed to assure the product’s continued safety, quality and purity. Under the goals and polices agreed to by the FDA under the Prescription Drug User Fee Act, or PDUFA, the FDA targets ten months, from the filing date, in which to complete its initial review of a new molecular entity NDA and respond to the applicant, and six months from the filing date of a new molecular entity NDA for priority review. The FDA does not always meet its PDUFA goal dates for standard or priority NDAs, and the review process is often extended by FDA requests for additional information or clarification.

Further, under PDUFA, as amended, each NDA must be accompanied by a user fee. The FDA adjusts the PDUFA user fees on an annual basis. Fee waivers or reductions are available in certain circumstances, including a waiver of the application fee for the first application filed by a small business. Additionally, no user fees are assessed on NDAs for products designated as orphan drugs, unless the product also includes a non-orphan indication.

The FDA also may require submission of a Risk Evaluation and Mitigation Strategy, or REMS, program if it believes that a risk evaluation and mitigation strategy is necessary to ensure that the benefits of the drug outweigh its risks. The REMS program could include use of risk evaluation and mitigation strategies like medication guides, physician communication plans, assessment plans and/or elements to assure safe use, such as restricted distribution methods, patient registries or other risk-minimization tools.

The FDA may refer an application for a novel drug to an advisory committee. An advisory committee is a panel of independent experts, including clinicians and other scientific experts, which reviews, evaluates and provides a recommendation

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as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

Before approving an NDA, the FDA typically will inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. Additionally, before approving an NDA, the FDA may inspect one or more clinical trial sites to assure compliance with GCP and other requirements and the integrity of the clinical data submitted to the FDA.

After evaluating the NDA and all related information, including the advisory committee recommendation, if any, and inspection reports regarding the manufacturing facilities and clinical trial sites, the FDA may issue an approval letter, or, in some cases, a complete response letter. A complete response letter generally contains a statement of specific conditions that must be met in order to secure final approval of the NDA and may require additional clinical or preclinical testing in order for the FDA to reconsider the application. Even with submission of this additional information, the FDA ultimately may decide that the application does not satisfy the regulatory criteria for approval. If and when those conditions have been met to the FDA’s satisfaction, the FDA will typically issue an approval letter. An approval letter authorizes commercial marketing of the drug with specific prescribing information for specific indications.

Even if the FDA approves a product, depending on the specific risk(s) to be addressed it may limit the approved indications for use of the product, require that contraindications, warnings or precautions be included in the product labeling, require that post-approval studies, including Phase 4 clinical trials, be conducted to further assess a drug’s safety after approval, require testing and surveillance programs to monitor the product after commercialization or impose other conditions, including distribution and use restrictions or other risk management mechanisms under a REMS, which can materially affect the potential market and profitability of the product. The FDA may prevent or limit further marketing of a product based on the results of post-marketing studies or surveillance programs. After approval, some types of changes to the approved product, such as adding new indications, manufacturing changes and additional labeling claims, are subject to further testing requirements and FDA review and approval.

Orphan Drug Designation and Exclusivity

Under the Orphan Drug Act of 1983, the FDA may grant orphan designation to a drug intended to treat a rare disease or condition, which is a disease or condition that affects fewer than 200,000 individuals in the U.S., or if it affects more than 200,000 individuals in the U.S., there is no reasonable expectation that the cost of developing and making the product available in the U.S. for the disease or condition will be recovered from sales of the product. Orphan designation must be requested before submitting an NDA. Orphan designation does not convey any advantage in or shorten the duration of the regulatory review and approval process, though companies developing orphan products are eligible for certain incentives, including tax credits for qualified clinical testing and waiver of application fees.

If a product that has orphan designation subsequently receives the first FDA approval for the disease or condition for which it has such designation, the product is entitled to a seven-year period of marketing exclusivity during which the FDA may not approve any other applications to market the same therapeutic agent for the same indication, except in limited circumstances, such as a subsequent product’s showing of clinical superiority over the product with orphan exclusivity or where the original applicant cannot produce sufficient quantities of product. Competitors, however, may receive approval of different therapeutic agents for the indication for which the orphan product has exclusivity or obtain approval for the same therapeutic agent for a different indication than that for which the orphan product has exclusivity. Orphan product exclusivity could block the approval of one of our products for seven years if a competitor obtains approval for the same therapeutic agent for the same indication before we do, unless we are able to demonstrate that our product is clinically superior. If an orphan designated product receives marketing approval for an indication broader than what is designated, it may not be entitled to orphan exclusivity. Further, orphan drug exclusive marketing rights in the U.S. may be lost if the FDA later determines that the request for designation was materially defective or the manufacturer of the approved product is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition.

In September of 2022, KT-333, Kymera’s STAT3 degrader in development for relapsed and/or refractory lymphomas and solid tumors, was granted its second orphan drug designation by the U.S. Food and Drug Administration for the treatment of cutaneous T-cell lymphoma (CTCL), following its orphan drug designation for peripheral T-cell lymphoma (PTCL) in June of 2022. These designations provide incentives to encourage the development of medicines for rare diseases.

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Expedited Development and Review Programs for Drugs

The FDA maintains several programs intended to facilitate and expedite development and review of new drugs to address unmet medical needs in the treatment of serious or life-threatening diseases or conditions. These programs include Fast Track designation, Breakthrough Therapy designation, Priority Review, Accelerated Approval and platform technology designation and the purpose of these programs is to either expedite the development or review of important new drugs to get them to patients earlier than under standard FDA development and review procedures.

A new drug is eligible for Fast Track designation if it is intended to treat a serious or life-threatening disease or condition and demonstrates the potential to address unmet medical needs for such disease or condition. Fast Track designation provides increased opportunities for sponsor interactions with the FDA during preclinical and clinical development, in addition to the potential for rolling review once a marketing application is filed, meaning that the agency may review portions of the marketing application before the sponsor submits the complete application, as well as Priority Review, discussed below.

In addition, a new drug may be eligible for Breakthrough Therapy designation if it is intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. Breakthrough Therapy designation provides all the features of Fast Track designation in addition to intensive guidance on an efficient drug development program beginning as early as Phase 1, and FDA organizational commitment to expedited development, including involvement of senior managers and experienced review staff in a cross-disciplinary review, where appropriate.

Any product submitted to the FDA for approval, including a product with Fast Track or Breakthrough Therapy designation, may also be eligible for additional FDA programs intended to expedite the review and approval process, including Priority Review designation and Accelerated Approval. A product is eligible for Priority Review if it has the potential to provide a significant improvement in safety or effectiveness in the treatment, diagnosis or prevention of a serious disease or condition. Under priority review, the FDA must review an application in six months compared to ten months for a standard review.

Additionally, products are eligible for Accelerated Approval if they can be shown to have an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or an effect on a clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality which is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit, taking into account the severity, rarity or prevalence of the condition and the availability or lack of alternative treatments.

Accelerated Approval is usually contingent on a sponsor’s agreement to conduct additional post-approval studies to verify and describe the product’s clinical benefit and, under the Food and Drug Omnibus Reform Act of 2022, or FDORA, the FDA is now permitted to require, as appropriate, that such trials be underway prior to approval or within a specific time period after the date of approval for a product granted accelerated approval. Under FDORA, the FDA has increased authority for expedited procedures to withdraw approval of a drug or indication approved under Accelerated Approval if, for example, the confirmatory trial fails to verify the predicted clinical benefit of the product. In addition, for products being considered for accelerated approval, the FDA generally requires, unless otherwise informed by the Agency, that all advertising and promotional materials that are intended for dissemination or publication within 120 days following marketing approval be submitted to the agency for review during the pre-approval review period, and that after 120 days following marketing approval, all advertising and promotional materials must be submitted at least 30 days prior to the intended time of initial dissemination or publication.

Under FDORA, a platform technology incorporated within or utilized by a drug or biological product is eligible for designation as a designated platform technology if (1) the platform technology is incorporated in, or utilized by, a drug approved under an NDA; (2) preliminary evidence submitted by the sponsor of the approved or licensed drug, or a sponsor that has been granted a right of reference to data submitted in the application for such drug, demonstrates that the platform technology has the potential to be incorporated in, or utilized by, more than one drug without an adverse effect on quality, manufacturing, or safety; and (3) data or information submitted by the applicable person indicates that incorporation or utilization of the platform technology has a reasonable likelihood to bring significant efficiencies to the drug development or manufacturing process and to the review process. A sponsor may request the FDA to designate a platform technology as a designated platform technology concurrently with, or at any time after, submission of an IND application for a drug that incorporates or utilizes the platform technology that is the subject of the request. If so designated, the FDA may expedite the development and review of any subsequent original NDA for a drug that uses or incorporates the platform technology.

Even if a product qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or the time period for FDA review or approval may not be shortened. Furthermore, Fast Track designation, Breakthrough Therapy designation, Priority Review and Accelerated Approval do not change the scientific or medical standards for approval or the quality of evidence necessary to support approval but may expedite the development or review process.

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Pediatric Information and Pediatric Exclusivity

Under the Pediatric Research Equity Act, or PREA, as amended, certain NDAs and certain supplements to an NDA must contain data to assess the safety and efficacy of the drug for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The FDA may grant deferrals for submission of pediatric data or full or partial waivers. The FD&C Act requires that a sponsor who is planning to submit a marketing application for a drug that includes a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration submit an initial Pediatric Study Plan, or PSP, within 60 days of an end-of-Phase 2 meeting or, if there is no such meeting, as early as practicable before the initiation of the Phase 3 or Phase 2/3 trial. The initial PSP must include an outline of the pediatric study or studies that the sponsor plans to conduct, including study objectives and design, age groups, relevant endpoints and statistical approach, or a justification for not including such detailed information, and any request for a deferral of pediatric assessments or a full or partial waiver of the requirement to provide data from pediatric studies along with supporting information. The FDA and the sponsor must reach an agreement on the PSP. A sponsor can submit amendments to an agreed-upon initial PSP at any time if changes to the pediatric plan need to be considered based on data collected from preclinical studies, early phase clinical trials and/or other clinical development programs.

A drug can also obtain pediatric market exclusivity in the U.S. Pediatric exclusivity, if granted, adds six months to existing exclusivity periods and patent terms. This six-month exclusivity, which runs from the end of other exclusivity protection or patent term, may be granted based on the voluntary completion of a pediatric trial or of multiple pediatric trials in accordance with an FDA-issued “Written Request” for such trials.

U.S. Post-Approval Requirements for Drugs

Drugs manufactured or distributed pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to recordkeeping, periodic reporting, product sampling and distribution, tracking and tracing, reporting of adverse experiences with the product, complying with promotion and advertising requirements, which include restrictions on promoting products for unapproved uses or patient populations (known as “off-label use”) and limitations on industry-sponsored scientific and educational activities. Manufacturers and other parties involved in the drug supply chain for prescription drug products must also comply with product tracking and tracing requirements and for notifying the FDA of counterfeit, diverted, stolen and intentionally adulterated products or products that are otherwise unfit for distribution in the United States. Although physicians may prescribe legally available products for off-label uses, manufacturers and individuals working on behalf of manufacturers may not market or promote such uses. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses, and a company that is found to have improperly promoted off-label uses may be subject to significant liability, including investigation by federal and state authorities. Prescription drug promotional materials must be submitted to the FDA in conjunction with their first use or first publication. Further, if there are any modifications to the drug, including changes in indications, labeling or manufacturing processes or facilities, the applicant may be required to submit and obtain FDA approval of a new NDA or NDA supplement, which may require the development of additional data or preclinical studies and clinical trials.

The FDA may impose a number of post-approval requirements as a condition of approval of an NDA. For example, the FDA may require post-market testing, including Phase 4 clinical trials, and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization.

In addition, drug manufacturers and their subcontractors involved in the manufacture and distribution of approved drugs, and those supplying products, ingredients, and components of them, are required to register their establishments with the FDA and certain state agencies and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with ongoing regulatory requirements, including cGMP, which impose certain procedural and documentation requirements upon us and our contract manufacturers. Failure to comply with statutory and regulatory requirements can subject a manufacturer to possible legal or regulatory action, such as warning letters, suspension of manufacturing, product seizures, injunctions, civil penalties or criminal prosecution. There is also a continuing, annual prescription drug product program user fee.

Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information, requirements for post-market studies or clinical trials to assess new safety risks, or imposition of distribution or other restrictions under a REMS. Other potential consequences include, among other things:

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Regulation of Companion Diagnostics

Companion diagnostics identify patients who are most likely to benefit from a particular therapeutic product; identify patients likely to be at increased risk for serious side effects as a result of treatment with a particular therapeutic product; or monitor response to treatment with a particular therapeutic product for the purpose of adjusting treatment to achieve improved safety or effectiveness. Companion diagnostics are regulated as medical devices by the FDA. In the U.S., the FD&C Act, and its implementing regulations, and other federal and state statutes and regulations govern, among other things, medical device design and development, preclinical and clinical testing, premarket clearance or approval, registration and listing, manufacturing, labeling, storage, advertising and promotion, sales and distribution, export and import, and post-market surveillance. Unless an exemption or FDA exercise of enforcement discretion applies, diagnostic tests generally require marketing clearance or approval from the FDA prior to commercialization. The two primary types of FDA marketing authorization applicable to a medical device are clearance of a premarket notification, or 510(k), and approval of a premarket approval application, or PMA.

To obtain 510(k) clearance for a medical device, or for certain modifications to devices that have received 510(k) clearance, a manufacturer must submit a premarket notification demonstrating that the proposed device is substantially equivalent to a previously cleared 510(k) device or to a preamendment device that was in commercial distribution before May 28, 1976, or a predicate device, for which the FDA has not yet called for the submission of a PMA. In making a determination that the device is substantially equivalent to a predicate device, the FDA compares the proposed device to the predicate device and assesses whether the subject device is comparable to the predicate device with respect to intended use, technology, design and other features which could affect safety and effectiveness. If the FDA determines that the subject device is substantially equivalent to the predicate device, the subject device may be cleared for marketing. The 510(k) premarket notification pathway generally takes from three to twelve months from the date the application is completed, but can take significantly longer.

A PMA must be supported by valid scientific evidence, which typically requires extensive data, including technical, preclinical, clinical and manufacturing data, to demonstrate to the FDA’s satisfaction the safety and effectiveness of the device. For diagnostic tests, a PMA typically includes data regarding analytical and clinical validation studies. As part of its review of the PMA, the FDA will conduct a pre-approval inspection of the manufacturing facility or facilities to ensure compliance with the Quality System Regulation, or QSR, which requires manufacturers to follow design, testing, control, documentation and other quality assurance procedures. The FDA’s review of an initial PMA is required by statute to take between six months, although the process typically takes longer, and may require several years to complete. If the FDA evaluations of both the PMA and the manufacturing facilities are favorable, the FDA will either issue an approval letter or an approvable letter, which usually contains a number of conditions that must be met in order to secure the final approval of the PMA. If the FDA’s evaluation of the PMA or manufacturing facilities is not favorable, the FDA will deny the approval of the PMA or issue a not approvable letter. A not approvable letter will outline the deficiencies in the application and, where practical, will identify what is necessary to make the PMA approvable. Once granted, PMA approval may be withdrawn by the FDA if compliance with post-approval requirements, conditions of approval or other regulatory standards is not maintained, or problems are identified following initial marketing.

On July 31, 2014, the FDA issued a final guidance document addressing the development and approval process for “In Vitro Companion Diagnostic Devices.” According to the guidance document, for novel therapeutic products that depend on the use of a diagnostic test and where the diagnostic device could be essential for the safe and effective use of the corresponding therapeutic product, the premarket application for the companion diagnostic device should be developed and approved or cleared contemporaneously with the therapeutic, although the FDA recognizes that there may be cases when contemporaneous development may not be possible. However, in cases where a drug cannot be used safely or effectively without the companion diagnostic, the FDA’s guidance indicates it will generally not approve the drug without the approval or clearance of the diagnostic device. The FDA also issued a draft guidance in July 2016 setting forth the principles for co-development of an in

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vitro companion diagnostic device with a therapeutic product. The draft guidance describes principles to guide the development and contemporaneous marketing authorization for the therapeutic product and its corresponding in vitro companion diagnostic.

Once cleared or approved, the companion diagnostic device must adhere to post-marketing requirements including the requirements of the FDA’s QSR, adverse event reporting, recalls and corrections along with product marketing requirements and limitations. Like drug makers, companion diagnostic makers are subject to unannounced FDA inspections at any time during which the FDA will conduct an audit of the product(s) and our facilities for compliance with its authorities.

Other Regulatory Matters

Manufacturing, sales, promotion and other activities of product candidates following product approval, where applicable, or commercialization are also subject to regulation by numerous regulatory authorities in the U.S. in addition to the FDA, which may include the Centers for Medicare & Medicaid Services, or CMS, other divisions of the Department of Health and Human Services, the Department of Justice, the Drug Enforcement Administration, the Consumer Product Safety Commission, the Federal Trade Commission, the Occupational Safety & Health Administration, the Environmental Protection Agency and state and local governments and governmental agencies.

Other Healthcare Laws

Healthcare providers, physicians, and third-party payors will play a primary role in the recommendation and prescription of any products for which we obtain marketing approval. Our business operations and any current or future arrangements with third-party payors, healthcare providers and physicians may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which we develop, market, sell and distribute any drugs for which we obtain marketing approval. In the United States, these laws include, without limitation, state and federal anti-kickback, false claims, physician transparency, and patient data privacy and security laws and regulations. If our operations are found to be in violation of any of such laws or any other governmental regulations that apply, we may be subject to penalties, including, without limitation, administrative, civil and criminal penalties, damages, fines, disgorgement, the curtailment or restructuring of operations, integrity oversight and reporting obligations, exclusion from participation in federal and state healthcare programs and responsible individuals may be subject to imprisonment.

The scope and enforcement of each of these laws is uncertain and subject to rapid change in the current environment of healthcare reform, especially in light of the lack of applicable precedent and regulations. Federal and state enforcement bodies have recently increased their scrutiny of interactions between healthcare companies and healthcare providers, which has led to a number of investigations, prosecutions, convictions and settlements in the healthcare industry. It is possible that governmental authorities will conclude that our business practices do not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other related governmental regulations that may apply to us, we may be subject to significant civil, criminal and administrative penalties, damages, fines, imprisonment, disgorgement, exclusion from government funded healthcare programs, such as Medicare and Medicaid, reputational harm, additional oversight and reporting obligations if we become subject to a corporate integrity agreement or similar settlement to resolve allegations of non-compliance with these laws and the curtailment or restructuring of our operations. If any of the physicians or other healthcare providers or entities with whom we expect to do business is found not to be in compliance with applicable laws, they may be subject to similar actions, penalties and sanctions. Ensuring business arrangements comply with applicable healthcare laws, as well as responding to possible investigations by government authorities, can be time- and resource-consuming and can divert a company’s attention from its business.

Insurance Coverage and Reimbursement

In the United States and markets in other countries, patients who are prescribed treatments for their conditions and providers performing the prescribed services generally rely on third-party payors to reimburse all or part of the associated healthcare costs. Thus, even if a product candidate is approved, sales of the product will depend, in part, on the extent to which third-party payors, including government health programs in the United States such as Medicare and Medicaid, commercial health insurers and managed care organizations, provide coverage, and establish adequate reimbursement levels for, the product. In the United States, the principal decisions about reimbursement for new medicines are typically made by the Centers for Medicare & Medicaid Services, or CMS, an agency within the U.S. Department of Health and Human Services. CMS decides whether and to what extent a new medicine will be covered and reimbursed under Medicare and private payors tend to follow CMS to a substantial degree. No uniform policy of coverage and reimbursement for drug products exists among third-party payors. Therefore, coverage and reimbursement for drug products can differ significantly from payor to payor. The process for determining whether a third-party payor will provide coverage for a product may be separate from the process for setting the price or reimbursement rate that the payor will pay for the product once coverage is approved. Third-party payors are increasingly challenging the prices charged, examining the medical necessity, reviewing the cost-effectiveness of medical

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products and services and imposing controls to manage costs. Third-party payors may limit coverage to specific products on an approved list, also known as a formulary, which might not include all of the approved products for a particular indication.

In order to secure coverage and reimbursement for any product that might be approved for sale, a company may need to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of the product, which will require additional expenditure above and beyond the costs required to obtain FDA or other comparable regulatory approvals. Additionally, companies may also need to provide discounts to purchasers, private health plans or government healthcare programs. Nonetheless, product candidates may not be considered medically necessary or cost effective. A decision by a third-party payor not to cover a product could reduce physician utilization once the product is approved and have a material adverse effect on sales, our operations and financial condition. Additionally, a third-party payor’s decision to provide coverage for a product does not imply that an adequate reimbursement rate will be approved. Further, one payor’s determination to provide coverage for a product does not assure that other payors will also provide coverage and reimbursement for the product, and the level of coverage and reimbursement can differ significantly from payor to payor.

The containment of healthcare costs has become a priority of federal, state and foreign governments, and the prices of products have been a focus in this effort. Governments have shown significant interest in implementing cost-containment programs, including price controls, restrictions on reimbursement and requirements for substitution of generic products. Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit a company’s revenue generated from the sale of any approved products. Coverage policies and third-party payor reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more products for which a company or its collaborators receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

Current and future healthcare reform legislation

In the United States and some foreign jurisdictions, there have been, and likely will continue to be, a number of legislative and regulatory changes and proposed changes regarding the healthcare system directed at broadening the availability of healthcare, improving the quality of healthcare, and containing or lowering the cost of healthcare. For example, in March 2010, the United States Congress enacted the Affordable Care Act, which, among other things, includes changes to the coverage and payment for products under government health care programs. The Affordable Care Act includes provisions of importance to our potential product candidates that:

Since its enactment, there have been numerous judicial, administrative, executive, and legislative challenges to certain aspects of the Affordable Care Act, and we expect there will be additional challenges and amendments to the Affordable Care Act in the future. On June 17, 2021, the U.S. Supreme Court dismissed the most recent judicial challenge to the ACA brought by several states without specifically ruling on the constitutionality of the ACA. Prior to the Supreme Court's decision, President Biden issued an Executive Order to initiate a special enrollment period from February 15, 2021 through August 15, 2021 for purposes of obtaining health insurance coverage through the ACA marketplace. The Executive Order also instructed certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, including among

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others, reexamining Medicaid demonstration projects and waiver programs that include work requirements, and policies that create unnecessary barriers to obtaining access to health insurance coverage through Medicaid or the ACA. It is unclear how other healthcare reform measures of the Biden administrations or other efforts, if any, to challenge repeal or replace the ACA, will impact our business.

Other legislative changes have been proposed and adopted in the United States since the Affordable Care Act was enacted. In August 2011, the Budget Control Act of 2011, among other things, included aggregate reductions of Medicare payments to providers of 2% per fiscal year, which went into effect in April 2013 and, due to subsequent legislative amendments to the statute, will remain in effect through 2030 unless additional Congressional action is taken. The Coronavirus Aid, Relief and Economic Security Act, or CARES Act, which was signed into law in March 2020 and is designed to provide financial support and resources to individuals and businesses affected by the COVID-19 pandemic, suspended these reductions from May 1, 2020, through March 31, 2022 due to the COVID-19 pandemic. Then, a 1% payment reduction occurred beginning April 1, 2022 through June 30, 2022, and the 2% payment reduction resumed on July 1, 2022. In January 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, further reduced Medicare payments to several providers, including hospitals, imaging centers and cancer treatment centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years.

Moreover, payment methodologies may be subject to changes in healthcare legislation and regulatory initiatives. For example, CMS may develop new payment and delivery models, including bundled payment models. In addition, recently there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their commercial products, which has resulted in several Congressional inquiries and proposed and enacted state and federal legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for pharmaceutical products. For example, at the federal level, the current administration’s budgets for fiscal years 2019 and 2020 contained further drug price control measures that could be enacted in future legislation, including, for example, measures to permit Medicare Part D plans to negotiate the price of certain drugs under Medicare Part B, to allow some states to negotiate drug prices under Medicaid, and to eliminate cost sharing for generic drugs for low-income patients. Additionally, the current administration released a “Blueprint” to lower drug prices and reduce out of pocket costs of drugs that contains additional proposals to increase drug manufacturer competition, increase the negotiating power of certain federal healthcare programs, incentivize manufacturers to lower the list price of their products, and reduce the out-of-pocket costs of drug products paid by consumers. The U.S. Department of Health and Human Services has already started the process of soliciting feedback on some of these measures and, at the same time, is immediately implementing others under its existing authority. For example, in May 2019, CMS issued a final rule to allow Medicare Advantage Plans the option of using step therapy, a type of prior authorization, for Part B drugs beginning January 1, 2020. This final rule codified CMS’s policy change that was effective January 1, 2019. Although a number of these and other measures may require additional authorization to become effective, Congress and the current administration have each indicated that it will continue to seek new legislative and/or administrative measures to control drug costs. Individual states in the United States have also increasingly passed legislation and implemented regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.

On May 30, 2018, the Right to Try Act was signed into law. The law, among other things, provides a federal framework for certain patients to access certain investigational new drug products that have completed a Phase 1 clinical trial and that are undergoing investigation for FDA approval. Under certain circumstances, eligible patients can seek treatment without enrolling in clinical trials and without obtaining FDA permission under the FDA expanded access program. There is no obligation for a drug manufacturer to make its drug products available to eligible patients as a result of the Right to Try Act.

In August 2022, the IRA was signed into law. The IRA includes several provisions that may impact our business to varying degrees, including provisions that establish a $2,000 out-of-pocket cap for Medicare Part D beneficiaries, impose new manufacturer financial liability on many drugs reimbursed under Medicare Part D, allow the U.S. government to negotiate Medicare Part B and Part D pricing for certain high-cost drugs and biologics without generic or biosimilar competition, and require companies to pay rebates to Medicare for drug prices that increase faster than inflation. The effect of IRA on our business and the healthcare industry in general is not yet known.

Outside the United States, ensuring coverage and adequate payment for a product also involves challenges. Pricing of prescription pharmaceuticals is subject to government control in many countries. Pricing negotiations with government authorities can extend well beyond the receipt of regulatory approval for a product and may require a clinical trial that compares the cost-effectiveness of a product to other available therapies. The conduct of such a clinical trial could be expensive and result in delays in commercialization.

In the European Union, pricing and reimbursement schemes vary widely from country to country. Some countries provide that products may be marketed only after a reimbursement price has been agreed upon. Some countries may require the

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completion of additional studies that compare the cost-effectiveness of a particular product candidate to currently available therapies or so-called health technology assessments, in order to obtain reimbursement or pricing approval. For example, the European Union provides options for its member states to restrict the range of products for which their national health insurance systems provide reimbursement and to control the prices of medicinal products for human use. European Union member states may approve a specific price for a product, or it may instead adopt a system of direct or indirect controls on the profitability of the company placing the product on the market. Other member states allow companies to fix their own prices for products but monitor and control prescription volumes and issue guidance to physicians to limit prescriptions. Recently, many countries in the European Union have increased the amount of discounts required on pharmaceuticals and these efforts could continue as countries attempt to manage healthcare expenditures, especially in light of the severe fiscal and debt crises experienced by many countries in the European Union. The downward pressure on healthcare costs in general, particularly prescription products, has become intense. As a result, increasingly high barriers are being erected to the entry of new products. Political, economic and regulatory developments may further complicate pricing negotiations, and pricing negotiations may continue after reimbursement has been obtained. Reference pricing used by various European Union member states, and parallel trade, i.e., arbitrage between low-priced and high-priced member states, can further reduce prices. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for any products, if approved in those countries.

Compliance with other federal and state laws or requirements; changing legal requirements

If any products that we may develop are made available to authorized users of the Federal Supply Schedule of the General Services Administration, additional laws and requirements apply. Products must meet applicable child-resistant packaging requirements under the U.S. Poison Prevention Packaging Act. Manufacturing, labeling, packaging, distribution, sales, promotion and other activities also are potentially subject to federal and state consumer protection and unfair competition laws, among other requirements to which we may be subject.

The distribution of pharmaceutical products is subject to additional requirements and regulations, including extensive recordkeeping, licensing, storage and security requirements intended to prevent the unauthorized sale of pharmaceutical products.

The failure to comply with any of these laws or regulatory requirements may subject firms to legal or regulatory action. Depending on the circumstances, failure to meet applicable regulatory requirements can result in criminal prosecution, fines or other penalties, injunctions, exclusion from federal healthcare programs, requests for recall, seizure of products, total or partial suspension of production, denial or withdrawal of product approvals, relabeling or repackaging, or refusal to allow a firm to enter into supply contracts, including government contracts. Any claim or action against us for violation of these laws, even if we successfully defend against it, could cause us to incur significant legal expenses and divert our management’s attention from the operation of our business. Prohibitions or restrictions on marketing, sales or withdrawal of future products marketed by us could materially affect our business in an adverse way.

Changes in regulations, statutes or the interpretation of existing regulations could impact our business in the future by requiring, for example: (i) changes to our manufacturing arrangements; (ii) additions or modifications to product labeling or packaging; (iii) the recall or discontinuation of our products; or (iv) additional recordkeeping requirements. If any such changes were to be imposed, they could adversely affect the operation of our business.

Other U.S. Environmental, Health and Safety Laws and Regulations

We may be subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. From time to time and in the future, our operations may involve the use of hazardous and flammable materials, including chemicals and biological materials, and may also produce hazardous waste products. Even if we contract with third parties for the disposal of these materials and waste products, we cannot completely eliminate the risk of contamination or injury resulting from these materials. In the event of contamination or injury resulting from the use or disposal of our hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

We maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees, but this insurance may not provide adequate coverage against potential liabilities. However, we do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. Current or future environmental laws and regulations may impair our research, development or production efforts. In addition, failure to comply with these laws and regulations may result in substantial fines, penalties or other sanctions.

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Government Regulation of Drugs Outside of the United States

To market any product outside of the U.S., we would need to comply with numerous and varying regulatory requirements of other countries regarding safety and efficacy and governing, among other things, clinical trials, marketing authorization or identification of an alternate regulatory pathway, manufacturing, commercial sales and distribution of our products. For instance, in the United Kingdom and the European Economic Area, or the EEA (comprised of the EU Member States plus Iceland, Liechtenstein and Norway), medicinal products must be authorized for marketing by using either the centralized procedure or a national procedure.

Now that the United Kingdom (which comprises Great Britain and Northern Ireland) has left the European Union, Great Britain is no longer covered by centralized marketing authorizations (under the Northern Ireland Protocol, centralized marketing authorizations will continue to be recognized in Northern Ireland). All medicinal products with a current centralized marketing authorization were automatically converted to Great Britain authorizations on January, 1, 2021. For a period of two years from January 1, 2021, the Medicines and Healthcare products Regulatory Agency, or MHRA, the UK medicines regulator, may rely on a decision taken by the European Commission on the approval of a new marketing authorization in the centralized procedure, in order to more quickly grant a new Great Britain marketing authorization. A separate application will, however, still be required. The MHRA also has the power to have regard to marketing authorizations approved in EU Member States through decentralized or mutual recognition procedures with a view to more quickly granting a marketing authorization in the United Kingdom or Great Britain.

In the EU, innovative medicinal products for therapeutic indications that are authorized for marketing (i.e., reference products) qualify for eight years of data exclusivity and an additional two years of market exclusivity upon marketing authorization. The data exclusivity period prevents generic or biosimilar applicants from referencing the innovator’s preclinical and clinical trial data contained in the dossier of the reference product when applying for a generic or biosimilar marketing authorization in the EU during a period of eight years from the date on which the reference product was first authorized in the

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EU. The market exclusivity period prevents a successful generic or biosimilar applicant from commercializing its product in the EU until ten years have elapsed from the initial authorization of the reference product in the EU. The ten-year market exclusivity period can be extended to a maximum of eleven years if, during the first eight years of those ten years, the marketing authorization holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies. There is no guarantee that a product will be considered by the EMA to be an innovative medicinal product, and products may not qualify for data exclusivity. Even if a product is considered to be an innovative medicinal product so that the innovator gains the prescribed period of data exclusivity, another company nevertheless could also market another version of the product if such company obtained marketing authorization based on an MAA with a complete independent data package of pharmaceutical tests, preclinical tests and clinical trials.

The criteria for designating an “orphan medicinal product” in the EU are similar in principle to those in the U.S. In the EU a medicinal product may be designated as orphan if: (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the EU when the application is made, or (b) it is unlikely that the product, without the benefits derived from orphan status, would generate sufficient return in the EU to justify the necessary investment in its development; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the EU or, if such a method exists, the product will be of significant benefit to those affected by that condition. Orphan medicinal products are eligible for financial incentives such as reduction of fees or fee waivers and are, upon grant of a marketing authorization, entitled to ten years of market exclusivity for the approved therapeutic indication. During this ten-year orphan market exclusivity period, no MAA shall be accepted, and no marketing authorization shall be granted for a similar medicinal product for the same therapeutic indication. A “similar medicinal product” is defined as a medicinal product containing a similar active substance or substances as contained in an authorized orphan medicinal product, and which is intended for the same therapeutic indication. An orphan product can also obtain an additional two years of market exclusivity in the EU where an agreed pediatric investigation plan for pediatric studies has been complied with. No extension to any supplementary protection certificate, or SPC, can be granted on the basis of pediatric studies for orphan indications. The ten-year market exclusivity may be reduced to six years if, at the end of the fifth year, it is established that the product no longer meets the criteria for orphan designation, for example, if the product is sufficiently profitable not to justify maintenance of market exclusivity. Additionally, marketing authorization may be granted to a similar product for the same therapeutic indication at any time if (i) the second applicant can establish that its product, although similar, is safer, more effective or otherwise clinically superior; (ii) the marketing authorization holder for the authorized orphan product consents to a second orphan medicinal product application; or (iii) the marketing authorization holder for the authorized orphan product cannot supply enough orphan medicinal product.

Prior to obtaining a marketing authorization in the EU, applicants must demonstrate compliance with all measures included in an EMA-approved pediatric investigation plan, or PIP, covering all subsets of the pediatric population, unless the EMA has granted a product-specific waiver, a class waiver, or a deferral for one or more of the measures included in the PIP. The respective requirements for all marketing authorization procedures are laid down in Regulation (EC) No 1901/2006, the so-called Pediatric Regulation. This requirement also applies when a company wants to add a new indication, pharmaceutical form or route of administration for a medicine that is already authorized. The Pediatric Committee of the EMA, or PDCO, may grant deferrals for some medicines, allowing a company to delay development of the medicine for children until there is enough information to demonstrate its effectiveness and safety in adults. The PDCO may also grant waivers when development of a medicine for children is not needed or is not appropriate, such as for diseases that only affect the elderly population. Before an MAA can be filed, or an existing marketing authorization can be amended, the EMA determines that companies actually comply with the agreed studies and measures listed in each relevant PIP. If an applicant obtains a marketing authorization in all EU Member States, or a marketing authorization granted in the centralized procedure by the European Commission, and the study results for the pediatric population are included in the product information, even when negative, the medicine is then eligible for an additional six-month period of qualifying patent protection through extension of the term of the SPC, provided an application for such extension is made at the same time as filing the SPC application for the product, or at any point up to 2 years before the SPC expires. In the case of orphan medicinal products, a two year extension of the orphan market exclusivity may be available. This pediatric reward is subject to specific conditions and is not automatically available when data in compliance with the PIP are developed and submitted.

Similar to as in the U.S., the various phases of non-clinical and clinical research in the European Union are subject to significant regulatory controls.

In April 2014, the EU adopted the new Clinical Trials Regulation, (EU) No 536/2014 (Clinical Trials Regulation) which replaced the Clinical Trials Directive 2001/20/EC on January 31, 2022. The Clinical Trials Regulation is directly applicable in all the EU Member States, meaning no national implementing legislation in each EU Member State is required. The extent to which ongoing clinical trials will be governed by the Clinical Trials Regulation will depend on the duration of the individual clinical trial. If a clinical trial continues for more than three years from the day on which the Clinical Trials Regulation became

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applicable the Clinical Trials Regulation will at that time begin to apply to the clinical trial. The new Clinical Trials Regulation aims to simplify and streamline the approval of clinical trials in the European Union.

The main characteristics of the regulation include: a streamlined application procedure via a single-entry point, the “Clinical Trials Information System” or CTIS; a single set of documents to be prepared and submitted for the application as well as simplified reporting procedures for clinical trial sponsors; and a harmonized procedure for the assessment of applications for clinical trials, which is divided in two parts. Part I is assessed by coordinated assessment by the competent authorities of all EU Member States in which an application for authorization of a clinical trial has been submitted (Member States concerned) following review by a Reference Member State. Part II is assessed separately by each Member State concerned. Strict deadlines have been established for the assessment of clinical trial applications. The role of the relevant ethics committees in the assessment procedure will continue to be governed by the national law of the concerned EU Member State. However, overall related timelines will be defined by the Clinical Trials Regulation.

The aforementioned EU rules are generally applicable in the European Economic Area, or EEA, which consists of the EU Member States, plus Norway, Liechtenstein and Iceland.

Government regulation of data collection outside of the United States

In the event we conduct clinical trials in the European Union, we will be subject to additional privacy restrictions. The collection and use of personal health data in the EEA is governed by the General Data Protection Regulation, or the GDPR, which became effective on May 25, 2018. The GDPR applies to the processing of personal data by any company established in the EEA and to companies established outside the EEA to the extent they process personal data in connection with the offering of goods or services to data subjects in the EEA or the monitoring of the behavior of data subjects in the EEA. The GDPR enhances data protection obligations for data controllers of personal data, including stringent requirements relating to the consent of data subjects, expanded disclosures about how personal data is used, requirements to conduct privacy impact assessments for “high risk” processing, limitations on retention of personal data, mandatory data breach notification and “privacy by design” requirements, and creates direct obligations on service providers acting as processors. The GDPR also imposes strict rules on the transfer of personal data outside of the EEA to countries that do not ensure an adequate level of protection, like the United States. Failure to comply with the requirements of the GDPR and the related national data protection laws of the EEA Member States, which may deviate slightly from the GDPR, may result in fines of up to 4% of a company’s global revenues for the preceding financial year, or €20,000,000, whichever is greater. Moreover, the GDPR grants data subjects the right to claim material and non-material damages resulting from infringement of the GDPR. Given the breadth and depth of changes in data protection obligations, maintaining compliance with the GDPR will require significant time, resources and expense, and we may be required to put in place additional controls and processes ensuring compliance with the new data protection rules. There has been limited enforcement of the GDPR to date, particularly in biopharmaceutical development, so we face uncertainty as to the exact interpretation of the new requirements on any future trials and we may be unsuccessful in implementing all measures required by data protection authorities or courts in interpretation of the new law. In addition, further to the United Kingdom’s exit from the European Union on January 31, 2020, the GDPR ceased to apply in the United Kingdom at the end of the transition period on December 31, 2020. However, as of January 1, 2021, the United Kingdom’s European Union (Withdrawal) Act 2018 incorporated the GDPR (as it existed on December 31, 2020, but subject to certain UK specific amendments) into UK law, referred to as the UK GDPR. The UK GDPR and the UK Data Protection Act 2018 set out the United Kingdom’s data protection regime, which is independent from but aligned to the European Union’s data protection regime. Non-compliance with the UK GDPR may result in monetary penalties of up to £17.5 million or 4% of worldwide revenue, whichever is higher. Although the UK is regarded as a third country under the European Union’s GDPR, the European Commission has now issued a decision recognizing the UK as providing adequate protection under the EU GDPR and, therefore, transfers of personal data originating in the EU to the UK remain unrestricted. Like the EU GDPR, the UK GDPR restricts personal data transfers outside the United Kingdom to countries not regarded by the United Kingdom as providing adequate protection. The UK government has confirmed that personal data transfers from the United Kingdom to the EEA remain free flowing.

There is significant uncertainty related to the manner in which data protection authorities will seek to enforce compliance with the GDPR. For example, it is not clear if the authorities will conduct random audits of companies doing business in the EEA, or if the authorities will wait for complaints to be filed by individuals who claim their rights have been violated. Enforcement uncertainty and the costs associated with ensuring GDPR compliance are onerous and may adversely affect our business, financial condition, results of operations and prospects.

Should we utilize third party distributors, compliance with such foreign governmental regulations would generally be the responsibility of such distributors, who may be independent contractors over whom we have limited control.

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Brexit and the Regulatory Framework in the United Kingdom

On June 23, 2016, the electorate in the United Kingdom voted in favor of leaving the European Union (commonly referred to as “Brexit”), and the UK formally left the EU on January 31, 2020. There was a transition period during which EU pharmaceutical laws continued to apply to the UK, which expired on December 31, 2020. However, the EU and the UK have concluded a trade and cooperation agreement, or TCA, which was provisionally applicable since January 1, 2021 and has been formally applicable since May 1, 2021. The TCA includes specific provisions concerning pharmaceuticals, which include the mutual recognition of GMP, inspections of manufacturing facilities for medicinal products and GMP documents issued, but does not foresee wholesale mutual recognition of UK and EU pharmaceutical regulations. At present, Great Britain has implemented EU legislation on the marketing, promotion and sale of medicinal products through the Human Medicines Regulations 2012 (as amended) (under the Northern Ireland Protocol, the EU regulatory framework will continue to apply in Northern Ireland). The regulatory regime in Great Britain therefore largely aligns with current EU regulations, however it is possible that these regimes will diverge in future now that Great Britain’s regulatory system is independent from the EU and the TCA does not provide for mutual recognition of UK and EU pharmaceutical legislation.

Employees and Human Capital

As of December 31, 2022, we had 167 full-time employees, of which 84 have M.D. or Ph.D. degrees. Within our workforce, 134 employees are engaged in research and development and 33 are engaged in business development, finance, legal, and general management and administration. We consider the intellectual capital of our employees to be an essential driver of our business and key to our future prospects. Our workforce expanded during FY22; new employees were hired to support and extend our clinical and preclinical pipeline, with hires in clinical development and operations, research, manufacturing, and general and administrative functions. We expect to continue to add additional employees in 2023 with a focus on expanding increasing expertise and bandwidth in clinical and preclinical research and development. We continually evaluate the business need and opportunity and balance in house expertise and capacity with outsourced expertise and capacity. Currently, we outsource substantially all clinical trial work to clinical research organizations and certain drug manufacturing to contract manufacturers. Drug development is a complex endeavor which requires deep expertise and experience across a broad array of disciplines. Pharmaceutical companies, both large and small, compete for a limited number of qualified applicants to fill specialized positions. We monitor our compensation programs closely and provide what we consider to be a very competitive mix of compensation and insurance benefits for all our employees, as well as participation in our equity programs. To attract qualified applicants, the Company offers a comprehensive benefits package consisting of base salary and cash target bonus, medical and other benefits and equity compensation for every employee. Bonus opportunity and equity compensation increase as a percentage of total compensation based on level of responsibility. Actual bonus payout is based on performance.

None of our employees is subject to a collective bargaining agreement or represented by a trade or labor union. We consider our relations with our employees to be good.

We support our employees’ further development with individualized development plans, mentoring, coaching, group training, conference attendance and financial support including tuition reimbursement.

Response to COVID-19

Beginning in March 2020, we have supported our employees and government efforts to curb the COVID-19 pandemic through a multifaceted communication, infrastructure, and behavior modification and enforcement effort. Practices that were implemented at different times in 2022 included the following:

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Facilities

Our corporate headquarters are located in Watertown, Massachusetts, where we lease and occupy approximately 34,522 square feet of office and laboratory space. The current term of our Watertown lease expires March 31, 2030, with an option to extend the term five additional years with 12 months’ notice with rent set at an agreed upon market rate.

On December 20, 2021, we entered into a noncancelable lease for 100,624 square feet of office and laboratory space in Watertown, Massachusetts. This lease has an initial term of 134 months, and we have two consecutive options to extend the term of the lease for five years each at then-market rates.

Our new facility is expected to be sufficient to meet our current needs. To meet the future needs of our business, we may lease additional or alternate space, and we believe suitable additional or alternative space will be available in the future on commercially reasonable terms.

Our Corporate Information

We were incorporated under the laws of Delaware in September 2015 under the name Project HSC, Inc. We are the successor in interest to Kymera Therapeutics, LLC, a limited liability company formed under the laws of the State of Delaware on May 25, 2017 and the former holder of all of our outstanding shares of common stock. Our principal executive offices are located at 200 Arsenal Yards Blvd., Suite 230, Watertown, MA 02472 and our telephone number is (857) 285-5300. Our website address is www.kymeratx.com. References to our website are inactive textual references only and the content of our website should not be deemed incorporated by reference into this Annual Report on Form 10-K.

Available Information

Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and any amendments to these reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act of 1934, are available free of charge on our website located at www.kymeratx.com as soon as reasonably practicable after they are filed with or furnished to the Securities and Exchange Commission, or the SEC.

The SEC maintains an Internet website that contains reports, proxy and information statements, and other information regarding us and other issuers that file electronically with the SEC. The SEC’s Internet website address is http://www.sec.gov.

A copy of our Corporate Governance Guidelines, Code of Business Conduct and Ethics and the charters of the Audit Committee, Compensation Committee and Nominating and Corporate Governance Committee are posted on our website, www.kymeratx.com, under “Investors”.

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Item 1A. Risk Factors.

Our business involves a high degree of risk. You should carefully consider the material and other risks and uncertainties described and summarized below, as well as the other information in this Annual Report on Form 10-K, including our consolidated financial statements and related notes and the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Special Note Regarding Forward-Looking Statements,” before you make an investment decision. Our actual results could differ materially from those anticipated in the forward-looking statements as a result of factors that are described below and elsewhere in this Annual Report on Form 10-K. The risks described below are not the only risks that we face. The occurrence of any of the events or developments described below could harm our business, financial condition, results of operations and prospects. As a result, the market price of our common stock could decline, and you may lose all or part of your investment in our common stock.

Risks Related to Our Financial Position and Need for Additional Capital

We are a biopharmaceutical company with a limited operating history and have not generated any revenue to date from drug sales, and may never become profitable.

Biopharmaceutical drug development is a highly speculative undertaking and involves a substantial degree of risk. Since our formation in 2015 and our initial funding in 2016, our operations to date have been limited primarily to organizing and staffing our company, business planning, raising capital, researching and developing our drug discovery technology, developing our pipeline, building our intellectual property portfolio, undertaking preclinical studies and conducting Phase 1 clinical trials of our product candidates. We have never generated any revenue from drug sales. We have not obtained regulatory approvals for any of our current product candidates. Typically, it takes many years to develop one new pharmaceutical drug from the time it is discovered to when it is available for treating patients. Consequently, any predictions we make about our future success or viability may not be as accurate as they could be if we had a longer operating history. In addition, as a business with a limited operating history, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors, such as the COVID-19 pandemic. We will need to transition from a company with a research and development focus to a company capable of supporting late-stage development and commercial activities. We may not be successful in such a transition.

We have incurred significant operating losses since our inception and anticipate that we will incur continued losses for the foreseeable future.

Since inception, we have focused substantially all of our efforts and financial resources on developing our proprietary targeted protein degradation drug discovery platform, or the PegasusTM platform, and initial product candidates as well as supporting our collaborations and partnerships. To date, we have financed our operations primarily through the issuance and sale of our convertible preferred stock to outside investors and collaborators in private equity financings, upfront payments under our existing collaborations and our initial public offering, follow-on offering and PIPE offering. From our inception through December 31, 2022, we raised an aggregate of approximately $1.03 billion of gross proceeds from such transactions and through our collaborations with Genzyme Corporation, or Sanofi, and Vertex Pharmaceuticals Incorporated, or Vertex. As of December 31, 2022, our cash and cash equivalents and investments were $559.5 million. We have incurred net losses in each year since our inception, and we had an accumulated deficit of $383.8 million as of December 31, 2022. For the years ended December 31, 2022, 2021 and 2020, we reported net losses of $154.8 million, $100.2 million and $45.6 million, respectively. Substantially all of our operating losses have resulted from costs incurred in connection with our research and development programs and from general and administrative costs associated with our operations. We expect to continue to incur significant expenses and increasing operating losses over the next several years and for the foreseeable future. Our prior losses, combined with expected future losses, have had and will continue to have an adverse effect on our stockholders’ deficit and working capital. We expect our expenses to significantly increase in connection with our ongoing activities, as we:

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In addition, if we obtain marketing approval for our current or future product candidates, we will incur significant expenses relating to sales, marketing, product manufacturing and distribution. Because of the numerous risks and uncertainties associated with developing pharmaceutical drugs, including in light of the ongoing evolution of the COVID-19 pandemic, we are unable to predict the extent of any future losses or when we will become profitable, if at all. Even if we do become profitable, we may not be able to sustain or increase our profitability on a quarterly or annual basis.

Risks Related to Future Financial Condition

We will need to raise substantial additional funding. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, scale back or discontinue some of our product candidate development programs or future commercialization efforts.

The development of pharmaceutical drugs is capital-intensive. We have commenced clinical development of KT-474, KT-413, and KT-333, and plan to initiate clinical development of KT-253 this year. We are also currently advancing multiple development candidates through preclinical development across a number of potential indications. We expect our expenses to increase substantially in connection with our ongoing activities, particularly as we continue the research and development of, advance the preclinical and clinical activities of, and seek marketing approval for, our current or future product candidates. In addition, if we obtain marketing approval for any of our current or future product candidates, we expect to incur significant commercialization expenses related to sales, marketing, product manufacturing and distribution to the extent that such sales, marketing, product manufacturing and distribution are not the responsibility of our collaborators. We may also need to raise additional funds sooner if we choose to pursue additional indications and/or geographies for our current or future product candidates or otherwise expand more rapidly than we presently anticipate. Furthermore, we expect to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on attractive terms, we would be forced to delay, scale back or discontinue the development and commercialization of one or more of our product candidates, and may be unable to expand our operations or otherwise capitalize on our business opportunities, as desired, which could materially affect our business, financial condition and results of operations.

As of December 31, 2022, we had approximately $559.5 million of cash and cash equivalents and investments. In August 2020, we completed an IPO of our common stock by issuing 9,987,520 shares of our common stock, including the exercise in full by the underwriters of their option to purchase up to 1,302,720 additional shares of common stock, at a public offering price of $20.00 per share. The aggregate gross proceeds to us from the offering, before deducting underwriting discounts and commissions, and other estimated offering expenses payable by us, were approximately $199.8 million. Concurrent with the IPO, we announced the sale of 676,354 common shares at the public offering price per share in a private placement to Vertex. The aggregate gross proceeds to us from the concurrent private placement were approximately $13.5 million. The concurrent private placement also closed in August 2020. In July 2021, we completed a follow-on offering of our common stock and an additional private placement transaction with Vertex resulting, in the aggregate, in net proceeds of approximately, $243.1 million. In August 2022, we completed a PIPE offering of our common stock and pre-funded warrants resulting in gross proceeds of $150.0 million. We expect that the approximately $559.5 million of cash and cash equivalents and investments at December 31, 2022 will be sufficient to fund our operations into the second half of 2025. We have based this estimate on assumptions that may prove to be wrong, and we could use our capital resources sooner than we currently expect. This estimate also assumes that we do not obtain any additional funding through collaborations or other strategic alliances. Our future capital requirements will depend on, and could increase significantly as a result of, many factors, including:

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Identifying potential product candidates and conducting preclinical studies and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve drug sales. In addition, our current or future product candidates, if approved, may not achieve commercial success. Our commercial revenues, if any, will be derived from sales of drugs that we do not expect to be commercially available for many years, if at all. Accordingly, we will need to continue to rely on additional funding to achieve our business objectives.

Any additional fundraising efforts may divert our management from their day-to-day activities, which may adversely affect our ability to develop and commercialize our current or future product candidates. Disruptions in the financial markets in general may make equity and debt financing more difficult to obtain and may have a material adverse effect on our ability to meet our fundraising needs. We cannot guarantee that future financing will be available in sufficient amounts or on terms favorable to us, if at all. Moreover, the terms of any financing may adversely affect the holdings or the rights of our stockholders and the issuance of additional securities, whether equity or debt, by us, or the possibility of such issuance, may cause the market price of our shares to decline. The sale of additional equity or convertible securities would dilute all of our stockholders. The incurrence of indebtedness would result in increased fixed payment obligations and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact our ability to conduct our business. We could also be required to seek funds through arrangements with collaborators or otherwise at an earlier stage than otherwise would be desirable and we may be required to relinquish rights to some of our technologies or current or future product candidates or otherwise agree to terms unfavorable to us, any of which may have a material adverse effect on our business, operating results and prospects.

We will continue to incur increased costs as a result of operating as a public company, and our management will be required to devote substantial time to new compliance initiatives.

As a public company, we will continue to incur significant legal, accounting and other expenses that we did not incur as a private company. We are subject to the reporting requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act, which require, among other things, that we file with the Securities and Exchange Commission, or the SEC, annual, quarterly and current reports with respect to our business and financial condition. In addition, the Sarbanes-Oxley Act of 2002, as amended, or Sarbanes-Oxley Act, as well as rules subsequently adopted by the SEC and The Nasdaq Global Market to implement provisions of the Sarbanes-Oxley Act, impose significant requirements on public companies, including requiring establishment and maintenance of effective disclosure and financial controls and changes in corporate governance practices. Further, in July 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act, or the Dodd-Frank Act, was enacted. There are significant corporate governance and executive compensation related provisions in the Dodd-Frank Act that require the SEC to adopt additional rules and regulations in these areas, such as “say on pay” and proxy access. We were required to implement these requirements beginning in 2022 and incurred unexpected expenses in connection with such implementation. Stockholder activism, the current political environment and the current high level of government intervention and regulatory reform may lead to substantial new regulations and disclosure obligations, which may lead to additional compliance costs and impact the manner in which we operate our business in ways we cannot currently anticipate.

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The rules and regulations applicable to public companies substantially increase our legal and financial compliance costs and make some activities more time-consuming and costly. If these requirements divert the attention of our management and personnel from other business concerns, they could have a material adverse effect on our business, financial condition and results of operations. The increased costs will decrease our net income or increase our net loss and may require us to reduce costs in other areas of our business. For example, we expect these rules and regulations to make it more difficult and more expensive for us to obtain director and officer liability insurance and we may be required to incur substantial costs to maintain the same or similar coverage. We cannot predict or estimate the amount or timing of additional costs we may incur to respond to these requirements. The impact of these requirements could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors, our board committees or as executive officers.

Risks Related to Drug Development and Regulatory Approval

Risks Related to Preclinical and Clinical Development

We are very early in our development efforts. All of our product candidates are in preclinical or early clinical development. If we are unable to commercialize our product candidates or experience significant delays in doing so, our business will be materially harmed.

Our ability to become profitable depends upon our ability to generate revenue. To date, while we have generated collaboration revenue, we have not generated any revenue from our product candidates, and we do not expect to generate any revenue from the sale of drugs in the near future. We do not expect to generate revenue from product sales unless and until we complete the development of, obtain marketing approval for, and begin to sell, one or more of our product candidates. We are also unable to predict when, if ever, we will be able to generate revenue from such product candidates due to the numerous risks and uncertainties associated with drug development, including the uncertainty of:

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We expect to incur significant sales and marketing costs as we prepare to commercialize our current or future product candidates. Even if we initiate and successfully complete pivotal or registration-enabling clinical trials of our current or future product candidates, and our current or future product candidates are approved for commercial sale, and despite expending these costs, our current or future product candidates may not be commercially successful. We may not achieve profitability soon after generating drug sales, if ever. If we are unable to generate revenue, we will not become profitable and may be unable to continue operations without continued funding.

Our approach to the discovery and development of product candidates based on our Pegasus platform is novel and unproven, which makes it difficult to predict the time, cost of development and likelihood of successfully developing any products.

Our PegasusTM platform utilizes a method known as targeted protein degradation, or TPD, to discover and develop product candidates. Our future success depends on the successful development of this novel therapeutic approach. No product candidate using a heterobifunctional degrader has been approved in the United States or Europe, and the data underlying the feasibility of developing such therapeutic products is both preliminary and limited. In addition, we have not yet succeeded and may not succeed in demonstrating the efficacy and safety of any of our product candidates in clinical trials or in obtaining marketing approval thereafter. In particular, our ability to successfully achieve TPD with a therapeutic result requires the successful development of heterobifunctional molecules that were intentionally designed with a rational drug development process and developing those molecules with the right combination of protein targets and E3 ligases. This is a complex process requiring a number of component parts or biological mechanisms to work in unison to achieve the desired effect. We cannot be certain that we will be able to discover degraders by matching the right target with the ideal E3 ligase and the right linker in a timely manner, or at all. All of our product candidates are in preclinical or early clinical development. As such, there may be adverse effects from treatment with any of our current or future product candidates that we cannot predict at this time.

As a result of these factors, it is more difficult for us to predict the time and cost of product candidate development, and we cannot predict whether the application of our PegasusTM platform, or any similar or competitive platforms, will result in the development and marketing approval of any products. Any development problems we experience in the future related to our PegasusTM platform or any of our research programs may cause significant delays or unanticipated costs or may prevent the development of a commercially viable product. Any of these factors may prevent us from completing our preclinical studies and clinical trials or commercializing any product candidates we may develop on a timely or profitable basis, if at all.

We may not be successful in our efforts to identify or discover additional product candidates or we may expend our limited resources to pursue a particular product candidate or indication and fail to capitalize on product candidates or indications that may be more profitable or for which there is a greater likelihood of success.

A key element of our strategy is to apply our PegasusTM platform and product pipeline to address a broad array of targets and new therapeutic areas. The therapeutic discovery activities that we are conducting may not be successful in identifying product candidates that are useful in treating oncology, inflammation, immunology or genetic diseases. Our research programs may be unsuccessful in identifying potential product candidates, or our potential product candidates may be shown to have harmful side effects or may have other characteristics that may make the products unmarketable or unlikely to receive marketing approval.

Because we have limited financial and management resources, we focus on a limited number of research programs and product candidates. We are currently focused on our four most advanced development programs, IRAK4, IRAKIMiD, STAT3 and MDM2, which target key signaling pathways implicated in multiple inflammatory and autoimmune diseases as well as numerous cancers. As a result, we may forego or delay pursuit of opportunities with other current or future product candidates or for other indications that later prove to have greater commercial potential. Our resource allocation decisions may cause us to fail to capitalize on viable commercial drugs or profitable market opportunities. Our spending on current and future research and development programs and current or future product candidates for specific indications may not yield any commercially viable drugs. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through future collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

We depend heavily on the successful development of our lead programs. We cannot be certain that we will be able to obtain regulatory approval for, or successfully commercialize, any of our current or future product candidates

We currently have no product candidates approved for sale and may never be able to develop marketable product candidates. Our business depends heavily on the successful development, regulatory approval and commercialization of our current or future product candidates, including our IRAK4, IRAKIMiD, STAT3 and MDM2 programs. The preclinical studies

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and clinical trials of our current or future product candidates are, and the manufacturing and marketing of our current or future product candidates will be, subject to extensive and rigorous review and regulation by numerous government authorities in the U.S. and in other countries where we intend to test or, if approved, market any of our current or future product candidates. Before obtaining regulatory approvals for the commercial sale of any of our current or future product candidates, we must demonstrate through preclinical studies and clinical trials that each product candidate is safe and effective for use in each target indication. Drug development is a long, expensive and uncertain process, and delay or failure can occur at any stage of any of our preclinical studies and clinical trials. This process can take many years and may include post-marketing studies and surveillance, which will require the expenditure of substantial resources. Of the large number of drugs in development in the U.S., only a small percentage will successfully complete the FDA regulatory approval process and will be commercialized, with similarly low rates of success for drugs in development in the European Union obtaining regulatory approval from the European Commission following scientific evaluation by the European Medicines Agency, or EMA. Accordingly, even if we are able to obtain the requisite financing to continue to fund our development and preclinical studies and clinical trials, we cannot assure you that any of our current or future product candidates will be successfully developed or commercialized. For example, in December 2020, we submitted an IND application for KT-474 to initiate a first-in-human Phase 1 randomized, double-blind, placebo-controlled clinical trial in healthy volunteers and patients with hidradenitis suppurativa (HS) or atopic dermatitis (AD). The program was initially placed on partial clinical hold regarding the multiple ascending dose (MAD) portion of the Phase 1 trial, pending FDA review of the interim data in healthy volunteers from the SAD portion of the trial. In June 2021, the FDA lifted the partial clinical hold on the MAD portion of the Phase 1 trial of KT-474 following review of interim SAD results. As a result, in July 2021, we initiated enrollment in the MAD portion of the Phase 1 trial of KT-474, including healthy volunteers. We completed dose escalation in the SAD and MAD portions of this Phase 1 trial in December 2021. We completed a single dose, food-effect cohort to establish the dose for the patient cohort, or Part C, of the KT-474 Phase 1 trial. Part C has completed and included patients with either moderate-to-severe HS or AD.

We are not permitted to market our current or future product candidates in the U.S. until we receive approval of a New Drug Application, or an NDA, from the FDA, in the European Union, or EU, until we receive approval of a marketing authorisation application, or an MAA, from the European Commission following scientific evaluation by the EMA, or in any other foreign countries until we receive the requisite approval from such countries. Obtaining approval of an NDA or MAA is a complex, lengthy, expensive and uncertain process, and the FDA or EMA may delay, limit or deny approval of any of our current or future product candidates for many reasons, including, among others:

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Any of these factors, many of which are beyond our control, could jeopardize our ability to obtain regulatory approval for and successfully market our current or future product candidates. Any such setback in our pursuit of regulatory approval would have a material adverse effect on our business and prospects.

If we experience delays or difficulties in the initiation or enrollment of patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented.

There may be delays in trial initiation, and we may not be able to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or similar regulatory authorities outside the U.S. In particular, our ability to open clinical sites and enroll patients may be significantly delayed by the evolving COVID-19 pandemic and we do not know the extent and scope of such disruptions of patient care or delays at this point. Moreover, some of our competitors have ongoing clinical trials for current or future product candidates that treat the same patient populations as our current or future product candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ current or future product candidates.

Patient enrollment may be affected by other factors including:

Interim, “topline,” and preliminary data from our clinical trials that we announce or publish from time to time, including relating to our Phase 1 clinical trials of KT-474, KT-413 and KT-333, may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we may publicly disclose preliminary or topline data from our preclinical studies and clinical trials, which is based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the topline or preliminary results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Topline data also remain subject to audit and verification procedures that may result in the final

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data being materially different from the preliminary data we previously published. As a result, topline data should be viewed with caution until the final data are available. From time to time, we may also disclose interim data from our clinical trials. Interim data from clinical trials that we may complete, including data from of our Phase 1 trials of KT-474, KT-413 and KT-333, are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available or as patients from our clinical trials continue other treatments for their diseases. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects. Further, disclosure of interim data by us or by our competitors could result in volatility in the price of our common stock.

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial, including our Phase 1 trials of KT-474, KT-413 and KT-333, is based on what is typically extensive information, and you or others may not agree with what we determine is material or otherwise appropriate information to include in our disclosure.

If the interim, topline, or preliminary data that we report differ from actual results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, our product candidates may be harmed, which could harm our business, results of operations, prospects or financial condition.

Positive results from early preclinical studies and clinical trials of our current or future product candidates are not necessarily predictive of the results of later preclinical studies and clinical trials of our current or future product candidates. If we cannot replicate the positive results from our preclinical studies of our current or future product candidates in our future clinical trials, we may be unable to successfully develop, obtain regulatory approval for and commercialize our current or future product candidates.

Positive results from our preclinical studies of our current or future product candidates, and any positive results we may obtain from our early clinical trials of our current or future product candidates, including our Phase 1 trial of KT-474, may not necessarily be predictive of the results from required later preclinical studies and clinical trials. Similarly, even if we are able to complete our planned preclinical studies or clinical trials of our current or future product candidates according to our current development timeline, the positive results from such preclinical studies and clinical trials of our current or future product candidates, including our Phase 1 trial of KT-474, may not be replicated in subsequent preclinical studies or clinical trials. Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials after achieving positive results in early-stage development, and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, preclinical findings made while clinical trials were underway or safety or efficacy observations made in preclinical studies and clinical trials, including previously unreported adverse events. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials nonetheless failed to obtain approval from the FDA or comparable foreign regulatory authority. If we fail to produce positive results in our planned preclinical studies or clinical trials of any of our current or future product candidates, the development timeline and regulatory approval and commercialization prospects for our current or future product candidates, and, correspondingly, our business and financial prospects, would be materially adversely affected.

Additionally, our planned or future clinical trials may utilize an “open-label” trial design, such as the open-label patient portion of our Phase 1 clinical trials of KT-474, KT-413, KT-333 and KT-253. An “open-label” clinical trial is one where both the patient and investigator know whether the patient is receiving the investigational product candidate or either an existing approved drug or placebo. Most typically, open-label clinical trials test only the investigational product candidate and sometimes may do so at different dose levels. Open-label clinical trials are subject to various limitations that may exaggerate any therapeutic effect as patients in open-label clinical trials are aware when they are receiving treatment. Open-label clinical trials may be subject to a “patient bias” where patients perceive their symptoms to have improved merely due to their awareness of receiving an experimental treatment. In addition, open-label clinical trials may be subject to an “investigator bias” where those assessing and reviewing the physiological outcomes of the clinical trials are aware of which patients have received treatment and may interpret the information of the treated group more favorably given this knowledge. The results from an open-label trial, including our Phase 1 trials of KT-474, KT-413 and KT-333, may not be predictive of future clinical trial results with any of our product candidates for which we include an open-label clinical trial when studied in a controlled environment with a placebo or active control

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The incidence and prevalence for target patient populations of our product candidates have not been established with precision. If the market opportunities for our product candidates are smaller than we estimate or if any approval that we obtain is based on a narrower definition of the patient population, our revenue and ability to achieve profitability will be adversely affected, possibly materially.

The precise incidence and prevalence for the indications being pursued by our current and future product candidates are currently unknown. Our projections of both the number of people who have these diseases, as well as the subset of people with these diseases who have the potential to benefit from treatment with our product candidates, are based on estimates. We are developing KT-474 for the treatment of a broad set of immunology-inflammation diseases, such as HS, an inflammatory skin disease, AD, and rheumatoid arthritis. The total addressable market opportunity for our product candidates will ultimately depend upon, among other things, their proven safety and efficacy, the diagnosis criteria included in the final label for each, whether our product candidates are approved for sale for these indications, acceptance by the medical community and patient access, product pricing and reimbursement. The number of patients for our product candidates in the United States and elsewhere may turn out to be lower than expected, patients may not be otherwise amenable to treatment with our products, or new patients may become increasingly difficult to identify or gain access to, all of which would adversely affect our results of operations and our business.

A pandemic, epidemic, or outbreak of an infectious disease, such as COVID-19 or its variants, may materially and adversely affect our business and our financial results and could cause a disruption to the development of our product candidate.

Public health crises such as pandemics or similar outbreaks could adversely impact our business. In December 2019, a novel strain of a virus named SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), or coronavirus, which causes COVID-19, surfaced in Wuhan, China and has since spread worldwide, including to Eastern Massachusetts where our primary office and laboratory space is located. The pandemic and policies and regulations implemented by governments in response to the pandemic, most of which have been lifted, have had a significant impact, both direct and indirect, on businesses and commerce. The coronavirus pandemic is evolving, and to date has led to the implementation of various responses, including government-imposed quarantines, travel restrictions and other public health safety measures. The extent to which the coronavirus impacts our operations or those of our third-party partners, including our preclinical studies or clinical trial operations, will also depend on future developments, which are highly uncertain and cannot be predicted with confidence, including the duration of the outbreak, new information that will emerge concerning the severity of the coronavirus and the actions to contain the coronavirus or treat its impact, among others. The continued spread of COVID-19 globally, including the ongoing identification of new variants of the virus, could adversely impact our preclinical or clinical trial operations in the U.S. and abroad, including our ability to recruit and retain patients and principal investigators and site staff who, as healthcare providers, may have heightened exposure to COVID-19. For example, similar to other biopharmaceutical companies, we may experience additional delays in enrolling subjects in our clinical trials. COVID-19 may also affect employees of third-party CROs located in affected geographies that we rely upon to carry out our clinical trials. In addition, the patient populations that our lead and other core product candidates target may be particularly susceptible to COVID-19 or its variants, which may make it more difficult for us to identify patients able to enroll in our clinical trials and may impact the ability of enrolled patients to complete any such trials. Any negative impact that the ongoing COVID-19 pandemic has to patient enrollment or treatment, or the execution of our product candidates could cause costly delays to clinical trial activities, which could adversely affect our ability to obtain regulatory approval for and to commercialize our product candidates, increase our operating expenses, and have a material adverse effect on our financial results.

Additionally, timely enrollment in clinical trials is dependent upon clinical trial sites which will be adversely affected by global health matters, such as pandemics. We are conducting and plan to conduct clinical trials for our product candidates in geographies which are currently being affected by the coronavirus. Some factors from the coronavirus outbreak that will delay or otherwise adversely affect enrollment in the clinical trials of our product candidates, as well as our business generally, include:

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We cannot presently predict the scope and severity of additional planned and potential shutdowns or disruptions of businesses and government agencies, such as the SEC or FDA. For example, since March 2020, the FDA has been working to resume pre-pandemic levels of inspection activities, including routine surveillance, bioresearch monitoring and pre-approval inspections. Should the FDA determine that an inspection is necessary for approval of any NDAs we may submit and an inspection cannot be completed during the review cycle due to restrictions on travel at that time, and the FDA does not determine a remote interactive evaluation to be adequate, the agency has stated that it generally intends to issue, depending on the circumstances, a complete response letter or defer action on the application until an inspection can be completed. During the COVID-19 public health emergency, a number of companies have announced receipt of complete response letters due to the FDA’s inability to complete required inspections for their applications. Regulatory authorities outside the U.S. may adopt similar restrictions or other policy measures in response to the COVID-19 pandemic and may experience delays in their regulatory activities.

These and other factors arising from the coronavirus could worsen. Any of these factors, and other factors related to any such disruptions that are unforeseen, could have a material adverse effect on our business and our results of operations and financial condition. Further, uncertainty around these and related issues could lead to adverse effects on the economy of the United States and other economies, which could impact our ability to raise the necessary capital needed to develop and commercialize our product candidates. Other global health concerns could also result in social, economic, and labor instability in the countries in which we or the third parties with whom we engage operate.

Our current or future product candidates may cause adverse or other undesirable side effects that could delay or prevent their regulatory approval, limit the commercial profile of an approved label, or result in significant negative consequences following marketing approval, if any.

All of our product candidates are in preclinical or early clinical development, and there may be adverse effects from treatment with any of our current or future product candidates that we cannot predict at this time. Undesirable side effects caused by our current or future product candidates could cause us to interrupt, delay or halt preclinical studies or could cause us or regulatory authorities to interrupt, delay or halt clinical trials and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other regulatory authorities. As is the case with many treatments for inflammatory and autoimmune diseases, cancer or other diseases, it is likely that there may be adverse side effects associated with the use of our product candidates. Additionally, a potential risk in any protein degradation product is that healthy proteins or proteins not targeted for degradation will be degraded or that the degradation of the targeted protein in itself could cause adverse events, undesirable side effects, or unexpected characteristics. It is possible that healthy proteins or proteins not targeted for degradation could be degraded using our degrader molecules in any of our current or future clinical studies. There is also the potential risk of delayed adverse events following treatment using any of our current or future product candidates.

These side effects could arise due to off-target activity, allergic reactions in trial subjects, or unwanted on-target effects in the body. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of these or other side effects. In such an event, our trials could be suspended or terminated and the FDA or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our current or future product candidates for any or all targeted indications. The drug-related side effects could affect patient recruitment or the ability of enrolled patients to complete the trial or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.

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Further, our current or future product candidates could cause undesirable side effects in clinical trials related to on-target toxicity. If on-target toxicity is observed, or if our current or future product candidates have characteristics that are unexpected, we may need to abandon their development or limit development to more narrow uses or subpopulations in which the undesirable side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. Many compounds that initially showed promise in early-stage testing for treating cancer or other diseases have later been found to cause side effects that prevented further development of the compound.

Further, clinical trials by their nature utilize a sample of the potential patient population. With a limited number of patients and limited duration of exposure, rare and severe side effects of our current or future product candidates may only be uncovered with a significantly larger number of patients exposed to the product candidate. If our current or future product candidates receive marketing approval and we or others identify undesirable side effects caused by such current or future product candidates after such approval, a number of potentially significant negative consequences could result, including:

We believe that any of these events could prevent us from achieving or maintaining market acceptance of the affected product candidates and could substantially increase the costs of commercializing our current or future product candidates, if approved, and significantly impact our ability to successfully commercialize our current or future product candidates and generate revenues.

Manufacturing our current or future product candidates is complex and we may encounter difficulties in production. If we encounter such difficulties, our ability to provide supply of our current or future product candidates for preclinical studies and clinical trials or for commercial purposes could be delayed or stopped.

The process of manufacturing our current or future product candidates is complex and highly regulated. We do not have our own manufacturing facilities or personnel and currently rely, and expect to continue to rely, on third parties for the manufacture of our current or future product candidates. These third-party contract manufacturing organizations, or CMOs, may not be able to provide adequate resources or capacity to meet our needs and may incorporate their own proprietary processes into our product candidate manufacturing processes. We have limited control and oversight of a third party’s proprietary process, and a third party may elect to modify its process without our consent or knowledge. These modifications, such as any impacting the product formulation, could negatively impact our manufacturing, including by resulting in product loss or failure that requires additional manufacturing runs or a change in manufacturer, either of which could significantly increase the cost of and significantly delay the manufacture of our current or future product candidates. Changes in manufacturers often involve changes in manufacturing procedures and processes, which could require that we conduct bridging studies between our prior clinical supply used in our clinical trials and that of any new manufacturer. We may be unsuccessful in demonstrating the comparability of clinical supplies which could require the conduct of additional clinical trials.

If any CMO with whom we contract fails to perform its obligations, we may be forced to enter into an agreement with a different CMO, which we may not be able to do on reasonable terms, if at all. This could significantly delay our clinical trials supply as we establish alternative supply sources. In some cases, the technical skills required to manufacture our product candidates or products, if approved, may be unique or proprietary to the original CMO and we may have difficulty, or there may be contractual restrictions prohibiting us from, transferring such skills to a back-up or alternate supplier, or we may be

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unable to transfer such skills at all. In addition, if we are required to change CMOs for any reason, we will be required to verify that the new CMO maintains facilities and procedures that comply with quality standards and with all applicable regulations. We will also need to verify, such as through a manufacturing comparability study, that any new manufacturing process will produce our product candidate according to the specifications previously submitted to the FDA or another regulatory authority. The delays associated with the verification of a new CMO could negatively affect our ability to develop product candidates or commercialize our products in a timely manner or within budget. Furthermore, a CMO may possess technology related to the manufacture of our product candidate that such CMO owns independently. This would increase our reliance on such CMO or require us to obtain a license from such CMO in order to have another CMO manufacture our product candidates. In addition, as our current or future product candidates progress through preclinical studies and clinical trials towards potential approval and commercialization, it is expected that various aspects of the manufacturing process will be altered in an effort to optimize processes and results. Such changes may require amendments to be made to regulatory applications which may further delay the timeframes under which modified manufacturing processes can be used for any of our current or future product candidates and additional bridging studies or trials may be required. Any such delay could have a material adverse impact on our business, results of operations and prospects.

Risks Related to Regulatory Approval

If we are not able to obtain, or if there are delays in obtaining, required regulatory approvals for our current or future product candidates, we will not be able to commercialize, or will be delayed in commercializing, our current or future product candidates, and our ability to generate revenue will be materially impaired.

Our current or future product candidates and the activities associated with their development and commercialization, including their design, testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale, distribution, import, and export, are subject to comprehensive regulation by the FDA and other regulatory agencies in the U.S. and by comparable authorities in other countries. Before we can commercialize any of our current and future product candidates, we must obtain marketing approval from the regulatory authorities in the relevant jurisdictions. We have not received approval to market any of our current product candidates from regulatory authorities in any jurisdiction, and it is possible that none of our current product candidates, nor any product candidates we may seek to develop in the future, will ever obtain regulatory approval. As a company, we have only limited experience in filing and supporting the applications necessary to gain regulatory approvals and expect to rely on third-party CROs and/or regulatory consultants to assist us in this process. Securing regulatory approval requires the submission of extensive preclinical and clinical data and supporting information to the various regulatory authorities for each therapeutic indication to establish the product candidate’s safety and efficacy. Securing regulatory approval also requires the submission of information about the drug manufacturing process to, and inspection of manufacturing facilities and often clinical sites by, the relevant regulatory authority. Our current or future product candidates may not be effective, may be only moderately effective or may prove to have undesirable or unintended side effects, toxicities or other characteristics that may preclude our obtaining marketing approval or prevent or limit commercial use.

The process of obtaining regulatory approvals, both in the U.S. and abroad, is expensive, may take many years if additional clinical trials are required, if approval is obtained at all, and can vary substantially based upon a variety of factors, including the type, complexity and novelty of the product candidates involved. Changes in marketing approval policies during the development period, changes in or the enactment of additional statutes or regulations, or changes in regulatory review for each submitted NDA or equivalent application type outside the U.S., may cause delays in the approval or rejection of an application. The FDA and comparable authorities in other countries have substantial discretion in the approval process and may refuse to accept any application or may decide that our data are insufficient for approval and require additional preclinical, clinical or other studies. Our current or future product candidates could be delayed in receiving, or fail to receive, regulatory approval for many reasons, including the following:

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Even if we were to obtain approval, regulatory authorities may approve any of our current or future product candidates for fewer or more