NASDAQ: WHWK

We submitted investigational new drug (“IND”) applications with the U.S. Food and Drug Administration (“FDA”) for HWK-007 for the treatment of solid tumors, including non-small cell lung cancer (“NSCLC”) and ovarian cancer, and HWK-016 for the treatment of ovarian and endrometrial cancers, in the fourth quarter of 2025; and we anticipate submitting an IND for HWK-206 for the treatment of small cell lung cancer ("SCLC") and neuroendocrine tumors (“NETs”) in mid-2026. The FDA has cleared the IND applications for HWK-007 and HWK-016 and the Phase 1 trials for each asset are now actively recruiting. We expect data readouts in the first half of 2027 from each trial. With these three assets, we have the ability to pursue multiple cancer indications with high potential in large addressable patient populations, including and beyond those indications currently expected to be targeted in the upcoming Phase 1 trials.

Our track record of strong execution of novel drug formulation, research, clinical development, and commercialization in oncology, combined with our deep understanding of ADCs positions us to unlock the high potential of this differentiated ADC portfolio. Our management team has extensive experience in the discovery, development, and commercialization of cancer therapeutics, including in senior roles at leading oncology companies. We are supported by our board of directors and specialized scientific advisors, who contribute their deep understanding of drug discovery and development. Furthermore, our investor base includes top life science investors. We believe that our team is well positioned to execute our strategy to develop and, if approved, commercialize the ADC Therapies and future pipeline assets to ultimately bring broad benefit to cancer patients worldwide.

Legacy FYARRO Business.

Historically, our lead drug product was FYARRO® (sirolimus protein-bound particles for injectable suspension (albumin-bound); nab-sirolimus), which combines two established technologies: nanoparticle albumin-bound (nab) technology and the anti-cancer agent, sirolimus. Nab-sirolimus is a potent inhibitor of the mTOR biological pathway with demonstrated anti-cancer activity in advanced malignant perivascular epithelioid cell tumor (“PEComa”), a rare cancer. We exclusively licensed FYARRO, previously called ABI-009, nab-sirolimus, from Abraxis BioScience, LLC, a wholly owned subsidiary of Celgene Corporation, which is a wholly owned subsidiary of Bristol-Myers Squibb Company (“BMS”) and we refer to the development, production and commercial sale of FYARRO herein as the “FYARRO Business”. On February 22, 2022, we

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launched FYARRO in the United States for treatment of advanced malignant PEComa and recognized net product sales of $7.1 million and $26.0 million for the years ended December 31, 2025 and 2024, respectively.

On December 19, 2024, we entered into a Stock Purchase Agreement (the “Divestiture Agreement”) with KAKEN INVESTMENTS INC., a Delaware corporation (“KAKEN”), KAKEN PHARMACEUTICAL CO., LTD (“Guarantor”), and Aadi Subsidiary, Inc., a Delaware corporation and our former wholly owned subsidiary and the operating company for the FYARRO Business (“Aadi Subsidiary”). Under the Divestiture Agreement, KAKEN acquired 100% of the outstanding shares of capital stock of Aadi Subsidiary from us at the closing of the transaction for a cash payment of $102.4 million (following applicable purchase price adjustments under the Divestiture Agreement) (the "FYARRO Divestiture"). The divestiture transaction closed on March 25, 2025 and, as a result, we no longer operate the FYARRO Business.

Our Strategy

Our vision is to make bold choices in applying technology to efficiently deliver improved oncology therapies for people living with difficult-to-treat cancers. The principal components of our strategy include:

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We leverage an optimized, next-generation ADC architecture.

Recently, next-generation ADCs have been associated with double-digit improvement in objective response rates (“ORR”) over first generation ADCs against the same target across a variety of solid tumors, including ovarian, breast cancer, and lung cancers. These next-generation ADC architectures are typified by improved linker-antibody stability, optimized pharmacokinetics and improved inhibitor payloads, such as using a TOP1 inhibitor in lieu of monomethyl auristatin E (“MMAE”).

Our ADC Therapies are designed to leverage an optimized, next-generation ADC architecture engineered for selective tumor delivery, modality-leading stability and optimized TOP1 inhibition for maximal tumor killing while minimizing potential toxicity.

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We preferentially pursue clinically validated targets and identify opportunities for differentiation.

Rather than expend resources on target discovery, we leverage our team’s deep experience in oncology and biologics, review existing oncology target literature, and engage with key opinion leaders to identify promising tumor antibodies, antibody conjugates, and antigens. We focus on tumor targets of product candidates previously tested in clinical trials by other biopharmaceutical companies and where the trials results were made available, the rationale for discontinuation of such product candidates were well-known and where we have identified opportunities for differentiation. We also prioritize those targets that we believe have both strong precedent data and potential broader applicability, including expansion beyond the indications in which they were initially tested.

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We innovate antibody design to improve ADC performance.

We strive to develop ADCs that couple next-generation ADC architecture with cutting-edge antibody strategies to further improve antibody performance, including, but not limited to, high affinity, biparatopic, Fc modifications that increase ADC potency or safety.

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We focus our development strategies to demonstrate differentiation of our assets compared to first generation ADCs to maximize our asset’s competitive profile.

Our development strategy leverages precedent data from first generation ADCs to benchmark potential improvements to guide further expansion in both precedent and non-precedent indications. We also plan to pursue combination strategies early in our programs to reach more patients and take full advantage of Project Frontrunner, the FDA’s effort to shift cancer therapeutics development in earlier lines of therapy.

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We utilize an efficient virtual model with outsourced clinical development and manufacturing.

We plan to utilize an outsourced model for research, development and manufacturing operations. Initially, we intend to continue to benefit from the continuity of partnership with WuXi Biologics and Hangzhou DAC for ADC manufacturing. We will expand our CRDMO network as appropriate as our portfolio advances further in clinical trials.

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We look to continue to build our portfolio through strategic partnerships. We plan to continue to use our management and board expertise, as well as our extensive network, to maximize and grow our portfolio through additional strategic partnerships and transactions.

Our Portfolio

We were deliberate in identifying promising tumor targets that are broadly expressed across multiple cancer types, and plan to focus our initial development efforts on high potential indications where first generation ADCs against these targets have already shown proof of concept in Phase 1 clinical trials. The three tumor targets we selected – PTK7, MUC16 and SEZ6 – are each validated by a first-generation ADC that demonstrated promising efficacy in key indications, but were discontinued, largely due to safety and limited therapeutic index. Importantly, we prioritized the ability to be in the clinic quickly, filing INDs for HWK-007, our PTK7-directed asset, and HWK-016, our MUC16-directed asset, in the fourth quarter of 2025 and we anticipate filing an IND for HWK-206, our SEZ6-directed asset, in mid-2026. The FDA has cleared the IND applications for HWK-007 and HWK-016 and the Phase 1 trials for each asset are now actively recruiting. We expect data readouts in the first half of 2027 from each trial.

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HWK-007 presents a differentiated opportunity as one of the first next-generation ADCs in clinical development for high PTK7 expressing cancers, including NSCLC, ovarian cancer, and several other major indications.

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HWK-016 is potentially the first ADC that targets membrane-bound portion of MUC16, a glycoprotein "super expressed" in gynecological cancers, including ovarian cancer, endometrial cancer and cervical cancer.

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HWK-206 is designed to bind to two epitopes on SEZ6, which is often overexpressed in cancers of neuroendocrine origin. We believe this biparatopic approach can potentially improve internalization and drive increased effectiveness of the ADC.

We believe that improving ADC architecture can increase treatment efficacy in solid tumors. Each of the ADC Therapies utilizes the advanced CPT113 linker-payload technology from Hangzhou DAC, which consists of a highly stable yet cleavable linker that delivers a TOP1 inhibitor payload, and high affinity antibodies designed using the industry-leading antibody capability of Wuxi Biologics. The portfolio leverages an advanced ADC platform technology and are engineered for minimal off-target toxicity, greater stability and higher therapeutic index. We believe these assets can potentially overcome the limitations that hindered the first generation ADC therapies, and show superior performance to other next generation ADCs in development, to deliver improved results for patients. Under the WuXi License Agreement, we have worldwide development and commercialization rights to all of our product candidates. We intend to develop each of our programs as a monotherapy and also in combination with other therapies.

Industry Background

Antibody-Drug Conjugates

An antibody-drug conjugate (“ADC”) consists of an antibody that is connected to a drug (the payload) via a linker. An ADC can be a preferred alternative to systemic chemotherapies, particularly for cancer such as solid tumors, as it can deliver potent antibody-directed payloads directly to the tumor cells. This targeted approach can limit off-target toxicities of chemotherapy and/or allow for greatly improved potency against cancer. With these improvements in cancer outcomes, the ADC market with an estimated nearly $11 billion in sales at the end of 2024 is expected to grow to over $23 billion by 2030, with some estimates as high as $50 billion.

As of the end of 2025, 15 ADCs have been approved by the FDA (mostly first generation; two have been withdrawn) against multiple cancers, including blood, breast, gynecological and lung cancers. Despite the benefit seen with first generation ADCs, there continues to be significant need for improved ADCs with safer payloads, improved stability and optimized pharmacokinetics. For example, first generation ADCs often use tubulin inhibitor-based payloads, such as MMAE-based payloads, that have been associated with a class effect of dose-limiting toxicities, like peripheral neuropathy, ocular toxicities and neutropenia.

Next-generation ADCs

Recent advances in ADCs have included replacing the tubulin inhibitor-based payloads with Topoisomerase I (“TOP1”) inhibitor payloads to reduce toxicity, improving linker stability to reduce circulating free payload, and increasing and

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optimizing the drug-to-antibody ratio (“DAR”) to improve pharmacokinetics and antitumor activity. In a number of ADC programs, next generation ADCs were shown to have improved ORR by approximately 15-45% over their first-generation precursors. For example, the ORR for ABBV-011, a calicheamicin-based ADC with a DAR of 2 and a non-cleavable linker, in small cell lung cancer (“SCLC”) was 19%, while the ORR for ABBV-706, a next-generation ADC with a TOP1 inhibitor payload and a DAR of 6, was 56%, representing a 37% higher response rate compared to ABBV-011.

1 Overall response rate in indicated Phase I patients; exception, Elahere phase III data in ovarian cancer

FRa, Folate receptor alpha; DM4, Ravtansine (tubulin inhibitor); TOPO1, Topoisomerase I inhibitor; MMAE, Monomethyl Auristatin E (tubulin inhibitor) OvCa, Ovarian Cancer; TNBC, Triple negative breast cancer; SCLC, Small cell lung cancer; NSCLC, non-small cell lung cancer; HER2+ BC, Human Epidermal Growth Factor Receptor 2 positive breast cancer.

Source: Published data; Whitehawk analysis.

Regarding a target in our portfolio, PTK7, the graphs below demonstrate the placement of phase 1 cofetuzumab pelidotin (“Cofe-P”) data – an established PTK7 benchmark – in the context of currently approved or late-stage ADC benchmarks for efficacy in ovarian and lung cancers. Our product candidate, HWK-007, is a PTK7 switch to an advanced platform, and therefore extrapolating from the prior examples above, we believe there could be meaningful efficacy gains in objective response rate over Cofe-P.

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1. Elahere and Rina-S. 2. Trodelvy and Datroway. Maitland et al. Clin Cancer Research, 2021: 27:4511–20. Elahere USPI and Lee, E.K. et al.; Annals of Oncology, Volume 35, S550; Paz-Ares L, Goto Y, Lim WDT, et al. Journal of Clinical Oncology. 2024;42(24):2860-2872.; Myung-Ju Ahn et al. JCO 43, 260-272(2025). DOI:10.1200/JCO-24-01544. ORR, objective response rate; Cofe-P, Cofetuzumab pelidotin.

Our Approach: CPT113-based ADC platform

Each of the ADC Therapies utilizes Hangzhou DAC’s CPT113 platform, which consists of a highly stable yet cleavable linker with proprietary carbon-bridge technology that delivers a TOP1 inhibitor payload. We believe that the CPT113 platform’s linker stability and payload has the potential to be highly competitive among the next generation ADC platforms. Hangzhou DAC selectively designed and synthesized an advanced linker and payload design that supports stability, limits free payload release and improves the pharmacokinetic characteristics for the associated ADCs. Separately from the ADC Therapies we are licensing, Hangzhou DAC has two internally developed programs utilizing the same platform and directed to different targets, DXC006 and DXC1002, that are currently in dose-escalating Phase 1 clinical trials in China.

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1.
Based on highest species reported in publications on file; note that stability is largely consistent (~1-5X differences) between species for an individual ADC.

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Calculated based on molar concentration of free payload and ADC in representative pharmacokinetic studies.

The payload component of CPT113 is a proprietary TOP1 inhibitor based on a modified form of exatecan. Exatecan is a semisynthetic, water-soluble derivative of camptothecin, a naturally occurring plant alkaloid that is known for its TOP1 inhibition and antitumor activity. TOP1 are necessary for normal and tumor cell growth, as they are involved in DNA supercoiling and repackaging of DNA during cell division. Inhibition of TOP1 prevents DNA from rejoining, thereby causing DNA breaks and leading to cell death.

Although exatecan has shown some antitumor activity, it has been associated with acute toxicity when delivered freely in the circulation, however, has been found to be highly effective as an ADC payload due to its ability to improve the overall efficacy and toxicity of the ADC. Multiple companies are utilizing pure exatecan or exatecan derivatives in their ADC platforms. Deruxtecan (“DXd”), for example, has been shown to have potent anti-tumor efficacy with an improved safety profile compared to pure exatecan. Trastuzumab deruxtecan (“T-DXd”), an ADC consisting of a humanized mAb trastuzumab (Herceptin) covalently linked to DXd, is approved for treatment of breast cancer, gastric cancer and gastroesophageal adenocarcinoma and sold by Daiichi Sankyo. Based on preclinical models of exatecan, our modified version retains potency and with our proprietary bioconjugation has minimal toxicity in regards to impact on the bone marrow. This heme-sparing profile helps address challenges like severe neutropenia that has emerged with exatecan-based and other TOP1 ADCs.

One advantage of the CPT113 platform is its relatively high stability. Many first generation ADCs were challenged by high free payload release in circulation. Many approved and marketed ADCs have 1 to 20 percent free payload released into the circulation, which limits their therapeutic windows because the high amounts of free payload can generate off-target side effects. Next generation ADC platforms in development generally seek to lower the amounts of free payload released into circulation. Based on reported pharmacokinetic results across different ADC programs, as shown in the figure below, the CPT113 platform is likely on par with or better than these latest platforms, demonstrating its highly competitive stability.

An important component to this stability is bioconjugation, or how the linker-payload is attached to the antibody. We estimate that more than 95% of new TOP1 ADCs in clinical development today still use an older bioconjugation process defined by single-chain, partial site-specific bioconjugation. The single chain bioconjugation process breaks the disulfide bonds that normally hold antibody heavy and light chains together – there are four paired bonds of eight cysteines that are broken. Many ADC developers add their single chain linker payloads onto those cysteines to form a typical DAR8 TOP1 ADC. Single

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chain bioconjugation is relatively simple, but inherently unstable. First, the removal of the normal disulfide bridges between antibody chains can make the whole antibody component of the ADC less stable. Second, once the ADC is exposed to conditions in the circulation, each single chain linker-payload conjugation may besubject to attack and cleavage due to conditions in the blood releasing free payload into circulation – payload that is no longer targeted to the tumor and can circulate to damage normal tissue. In essence, standard single chain conjugation is relatively fragile and may be prone to free payload release that could lead to high rates of class payload toxicities.

Conversely, CPT113 adds linker-payloads on to the mAb as carbon-bonded pairs – that is two linker-payloads that are covalently bound together are added to the exact location where the disulfides on monoclonals have previously been broken. This strategy effectively re-bridges the native paired cysteines, replacing the disulfide bond with a new carbon bond in the linker. This “carbon bridge cysteine re-pairing” method restores the antibody’s more natural state, which we have demonstrated preclinically to enhance overall ADC stability beyond what is traditionally achieved by single chain bioconjugation.

We also employ an additional bioconjugation step - linker hydrolysis - to lock the carbon bridge structure of the ADC, further improving stability, reducing free payload release and limiting potential payload toxicity.

In addition to the exatecan-based TOP1 design, we have further optimized our linker-payload. We utilize PEG-based masking to optimize hydrophobicity of our linker, supporting longer ADC half-life in circulation and optimal ADC dosing. We layer on to that a novel, triple-peptide, intracellular cleavage site that ensures a controlled release profile of cytotoxic payload only once the ADC is inside the tumor cell.

Taken together, we believe these elements represent an elegant and cohesive engineering solution designed to deliver best-in-class stability, safety and tumor potency.

We believe that TOP1-based platforms are not all created equal. Based on key preclinical measures of tumor potency, stability and safety, the ADC Therapies demonstrated quantifiable advantages compared with the average TOP1-based ADCs.

Regarding tumor potency, across xenograft models our ADC Therapies achieve tumor reduction at doses roughly 3 to 10 times lower than conventional TOP1-based ADCs. This increased potency can translate lower minimally effective dose needed to achieve tumor regression in humans.

In addition, we consistently see 5 to 25 times lower levels of free payload in plasma in our ADC Therapies in nonclinical models compared to other TOP1-based ADCs. This advantage in stability is a function of our “carbon bridge cysteine re-pairing” and other aspects of our novel chemistry which sequesters the payload in place until it reaches the tumor cell.

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Finally, due to improved targeting, stability and novel payload, we observe a 2 to 3 times higher safety margin in nonclinical models of our ADC Therapies than the typical TOP1-based ADCs.

Taken together, we believe we have a differentiated next-generation platform with the potential for powerful tumor killing and lower side effects.

Our Product Candidates

HWK-007

Overview

HWK-007 is a differentiated next-generation ADC with a DAR of 6 targeting Protein Tyrosine Kinase 7 (PTK7). There are no approved PTK7-directed ADCs.

Following the submission of an IND in the fourth quarter of 2025 and the FDA's subsequent clearance of the IND, HWK-007 is now being explored in a Phase 1 trial that will initially evaluate activity in lung and ovarian cancers, two

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PTK7-expressing tumor types with established precedent data, as well as endometrial cancer, one of the highest PTK7-expressing tumor types. We expect data readout in the first half of 2027 from the Phase 1 trial.

HWK-007 has shown superior cytotoxic activity compared to a first generation MMAE-based PTK7 ADC in both in vitro and in vivo preclinical models. With its optimized linker and TOP1 inhibitor payload, we hope to improve upon the initial ORRs seen with Cofe-P, a first-generation MMAE-based ADC with a DAR 4 targeting PTK7.

Target Overview: Protein tyrosine kinase 7 (PTK7)

Protein tyrosine kinase 7 (PTK7) is an oncofetal pseudokinase also known as colon carcinoma kinase 4 (“CCK-4”). PTK7 is a transmembrane protein with an extracellular region comprised of 7 Ig domains and an intracellular domain that is non-catalytic.

PTK7 drives embryonic early development by regulating cell polarity, movement and development of hematopoietic and somatic progenitor cells often interacting with ligands, co-receptors and intracellular transducers in the Wnt signaling pathway. PTK7 is subsequently down-regulated in adult tissues and is known as a catalytically inactive receptor tyrosine kinase (RTK).

A large-scale RNA analysis of >157,000 tumor samples, nearly half from metastatic lesions, found PTK7 to be the third most highly expressed tumor marker among clinically validated and emerging ADC targets, present in approximately 70% of tumors. Highest median PTK7 mRNA expression was observed in endometrial (7.4), ovarian (7.2), head and neck (7.1), non-small cell lung cancer (NSCLC) (6.9) and breast (6.7) tumors. The analysis found stable expression across disease stages and metastatic status, underscoring relevance in both early- and late-stage disease. It also found expression levels comparable to or exceeding clinically validated and emerging ADC targets:

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Lung cancer: Comparable to HER2, HER3, Trop-2 and cMET.

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Ovarian cancer: Comparable to HER2 and FRα; markedly higher than CDH6, B7-H4 and CLDN6.

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Endometrial cancer: Comparable to Trop-2; markedly higher than FRα, B7-H4 and HER2.

We estimate that nearly 750,000 patients have PTK7-positive cancers in the United States alone, underscoring its potential as a tumor marker.

PTK7 is almost exclusively re-expressed in primary and metastatic tumor cells and cancer associated fibroblasts (“CAFs”) in the tumor microenvironment. PTK7 is known to promote cancer growth and invasion. Overexpression of PTK7 is associated with poor prognosis, tumor metastasis, and reduced overall survival.

Matulonis, et al., Real-World Characterization of PTK7, an Oncofetal Pseudokinase Expressed in Multiple Solid Tumors [Poster], presented at ENA 2025.

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Gene expression data were derived from a whole-transcriptome RNA-sequencing panel (Tempus’ xR) capturing 20,000 genes.

1. Among clinically validated and emerging ADC targets. 2. Across 17 indications (pan-cancer, N=122,228), weighted by SEER incidence.

TPM, transcripts per million

PTK7 is a clinically validated tumor target. In a Phase 1 trial in patients with advanced solid tumors, including PROC, NSCLC or triple-negative breast cancer (“TNBC”), Cofe-P demonstrated clinical activity with ORR ranging from 16 to 27% in all evaluable patients and 23 to 46% in the subgroup with moderate or high expression of PTK7 (“PTK7 mod-high”), as confirmed by immunohistochemistry (IHC) analysis of tumor tissues. In patients treated every three weeks (“Q3W”) cohort, ORR was up to 46% compared to 27% in patients with PROC compared to patients with PTK7 mod-high PROC, 25% compared to 16% in patients with NSCLC compared to patients with PTK7 mod-high NSCLC and 23% compared to 21% in patients with TNBC compared to patients with PTK7 mod-high TNBC. This is an important finding as PTK7 is an ADC target where a high proportion of marker-positive patients express PTK7 at moderate to high levels.

Despite these encouraging signals, Cofe-P’s commercial potential was limited by the reduced dose intensity and narrow therapeutic window driven by toxicities consistent with MMAE-associated class effects, including Grade 3 headache and fatigue. Additionally, 25% (28/112) of the Q3W cohort experienced Grade 3 neutropenia. Overall, common treatment-related adverse events included nausea, alopecia, fatigue, headache, neutropenia and vomiting.

* Mod-high ORR reflects Whitehawk analysis of the PTK7 protein expression and best overall response data for Q3W cohorts in Figure 2 of Maitland et al. Clin Cancer Research, 2021: 27:4511–20. There were 13, 16, and 13 patients with mod-high PTK 7 expressions in PROC, NSCLC, and TNBC, respectively.

Emerging Therapies and their Limitations

Although there are currently no approved ADCs targeting PTK7, there are multiple PTK7 programs currently in, or about to begin, clinical development, some of which are described here:

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DAY301 (MTX-13), being developed by Day One Biopharmaceuticals after acquiring development and commercialization rights outside of the Greater China area from MabCare Therapeutics, is being explored in a Phase 1 trial.

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LY4175408, being developed by Eli Lilly, also has a pure exatecan payload and is being explored in a Phase 1 trial.

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SKB518, being developed by Kelun Biotech, is currently in Phase 1 in China.

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KIVU-107, being developed by Kivu Bioscience, uses a pure exatecan payload and is being explored in a Phase 1 trial.

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IDE034, being developed by Ideaya Biosciences, an investigational PTK7/B7H3 bispecific TOP1 ADC being explored in a Phase 1 trial.

We expect multiple external PTK7 ADC programs are projected to present clinical data in 2026 to 2027, which will further validate our target and TOP1 inhibitor payload approach. Additionally, there are multiple preclinical PTK7 bispecific ADCs in development. There are a number of other ADC programs in development for NSCLC targeting other tumor-associated antigens.

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Our Product Candidate: HWK-007

HWK-007, as a differentiated next-generation PTK7-directed ADC, is poised among the first in next-generation ADCs with an alternate TOP1 inhibitor payload to enter the clinic. With its optimized linker and TOP1 inhibitor payload switch, we are targeting to build on the initial ORRs seen with Cofe-P and potentially deliver superior outcomes for patients.

HWK-007 has already demonstrated superior tumor reduction compared to Cofe-P in both in vitro and in vivo preclinical models. HWK-007 shows superior tumor reduction in a lung cancer cell lines compared to similar doses of Cofe-P. The in vivo antitumor studies were conducted with human tumor xenografts with moderate to high PTK7 expression in nude mice (n=8 per xenograft). As shown in the figure below, in human SCLC xenograft models NCI-H446 (PTK7-mod), both HWK-007 and Cofe-P showed clear dose response in antitumor activity but HWK-007 demonstrated increased antitumor activity compared to Cofe-P at each corresponding dose with tumor regression achieved by HWK-007 at higher doses. Similar results were also observed in xenograft models from other tumor types.

Clinical Development Plan

In the fourth quarter of 2025, we completed IND-enabling studies and linker-payload process development, submitted an IND for the treatment of solid tumors, including NSCLC, PROC and endometrial, and initiated a Phase 1 trial for HWK-007. The Phase 1 clinical trial, HWK-007-101, is a Phase 1, multicenter, open-label study in adult participants that will employ a sequential dose-escalation and expansion design to evaluate the safety, pharmacokinetics and preliminary antitumor activity of HWK-007 in participants with advanced or metastatic solid tumors that are refractory to standard therapies. We expect data readout in the first half of 2027 from HWK-007-101.

HWK-016

Overview

Our product candidate HWK-016 is a next-generation ADC targeting the membrane-bound portion of MUC16, a glycoprotein "super expressed" in gynecological cancers, such as ovarian, endometrial and cervical cancers. MUC16 has

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been previously a challenging target because a large part of its extracellular portion is often cleaved and released or “shed” into the bloodstream, often called cancer antigen 125 (“CA125”). HWK-016 is specifically designed to bind to the membrane-bound portion, which we believe can enable greater therapeutic effect at lower doses. We plan to develop HWK-016 initially for the treatment of ovarian and endometrial cancers, aiming to deliver a potential best-in-class treatment for these large patient populations.

Our in vitro and in vivo studies show consistent cytotoxic activity by HWK-016, including in the presence of CA125, suggesting that our product candidate does bind to the right epitope. Our product candidate also has an optimized linker and improved TOP1 inhibitor payload, which we expect can improve response rate and reduce toxicity. We submitted an IND for the treatment of ovarian cancer in the fourth quarter of 2025, which was subsequently cleared by the FDA, and initiated a Phase 1 clinical trial of HWK-016 in participants with advanced or metastatic solid tumors that are refractory to standard therapies in the first quarter of 2026. We expect data readout in the first half of 2027 from the Phase 1 trial.

Target Overview: Mucin 16 (MUC16)

Mucin 16 (MUC16) is a heavily glycosylated type 1 transmembrane protein with a low level of expression in normal bronchial, endometrial, ovarian and corneal epithelial cells.

MUC16 is upregulated in a number of cancers, with broad overexpression - or "super expression" - in gynecological tumors including ovarian, cervical and endometrial. In ovarian cancer, for example, MUC16 is present at rates up to 3-10 times higher than clinically validated and emerging ADC targets. Overexpression of MUC16 promotes cancer cell proliferation and chemoresistance, while also inhibiting anti-cancer immune responses. Knockdown of MUC16 has been shown to reduce tumor growth, motility, and invasiveness, while overexpression enhances these properties.

MUC16 interacts with various signaling pathways and proteins, such as the JAK2/STAT3/GR axis, PI3k, EGFR and Src family kinases.

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Pan-cancer, N=4030. TPM, transcripts per million. Data on file. RNA sequencing data (Tempus AI, Inc.) were used to examine MUC16 expression across ovarian cancer histologic subtypes. Median mRNA expression was quantified as log2(transcripts per million [TPM]+1 and differences were evaluated using the Kruskal-Wallis test.

MUC16 consists of an O-glycosylated N-terminal domain, a tandem repeat domain, approximately 56 SEA (sperm protein, enterokinase and agrin) domains, a transmembrane domain and a cytoplasmic tail. MUC16 is unique in its large number of SEA domains, as other mucins such as MUC1, MUC12, MUC13, and MUC17 only possess a single SEA module. SEA

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domains and their functions are not fully understood but MUC16 is speculated to have two proteolytic sites in the SEA domains, at the 55th and 56th SEA domains. It is believed that MUC16 cleavage occurs at these sites, whereby CA125 is released or “shed” into the bloodstream. The serum levels of CA125 serve as a biomarker for cancer screening and disease monitoring; CA125 is one of the best-known blood biomarkers for ovarian cancer and elevated levels are strongly associated with poor prognosis.

MUC16 is a clinically validated tumor target, including by DMUC4064A, a first generation MMAE-based ADC targeting the tandem repeat region of MUC16, that demonstrated efficacy in PROC in an open-label Phase 1 trial. DMUC4064A, which has a protease-cleavable linker with a DAR of 2, demonstrated 42% ORR at the recommended Phase 2 dose.

Despite this promising response rate, DMUC4064A development was discontinued in 2021 due to a limited therapeutic index, toxicities consistent with MMAE class effects and binding to circulating CA125 that may have hindered effectiveness, also known as an “antigen sink.” Patients treated with DMUC4064A experienced toxicities consistent with other MMAE-based therapies, with 40% of patients reporting ocular toxicities, including Grade 3 ocular events in 9%. Although MUC16 is expressed in certain ocular cell types, we believe the frequency and severity of ocular toxicities were primarily driven by the MMAE payload rather than on-target effects from MUC16 binding. Overall, 25% experience Grade 3 or higher treatment-related adverse events. Common adverse events included fatigue, nausea, abdominal pain, constipation, blurred vision, diarrhea, anemia and peripheral neuropathy. Additionally, lower doses did not produce objective responses, likely due to a portion of the ADC binding to circulating CA125. Consequently, higher doses were necessary to first saturate most of the circulating CA125 before achieving therapeutic efficacy and tumor cell killing.

Sources: Liu J, et al. Gynecol Oncol. 2021;163(3):473-480; Liu J, et al. Ann Oncol. 2016;27(11):2124-2130; Chen Y, et al. Cancer Res. 2007;67(10):4924-4932. ORR, objective response rate.

Emerging Therapies and their Limitations

Currently, there are no approved ADCs targeting MUC16. Regeneron is developing two MUC16 bispecific T cell-engaging antibodies; a limitation of this approach, however, includes the modest ORRs observed to date. While several ADCs targeting other antigens in PROC are under development, none offer the combined advantages of high target expression in both depth and frequency, along with the potential for a matched blood-based biomarker like CA125.

Our Product Candidate: HWK-016

Our product candidate is designed to bind to a different region than the targets of prior MUC16 therapies in development. HWK-016 targets membrane-bound MUC16 (mMUC16) below the site of cleavage, so that even if MUC16 is cleaved and release of CA125 occurs, the ADC can stay bound to the cell surface permitting internalization of the TOP1 inhibitor payload. This allows HWK-016 to bypass the antigen sink of circulating CA125, and directly target the tumor surface.

Preclinical data shows that HWK-016 demonstrates superior tumor growth inhibition in vivo compared to DMUC4064A in a high CA125-shedding model of ovarian cancer. In vitro and in vivo data suggest that this next-generation approach has the potential for improved response rates in ovarian cancer and other gynecological cancers. For example, our product candidate

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HWK-016, along with DMUC and mMUC16 antibodies conjugated to DXd and MMAE payloads, were tested in an in vivo OVCAR-3 CDX model. Nude mice bearing the OVCAR-3 tumor xenograft were treated with a single dose of ADC at 1 mg/kg. mMUC16 ADCs displayed significantly increased in vivo antitumor activity compared to DMUC ADCs, regardless of the cytotoxic payload. No obvious weight loss was observed in any group.

Clinical Development Plan

We completed IND-enabling studies and linker-payload process development in 2025 and submitted an IND in the fourth quarter of 2025. In the first quarter of 2026, we initiated HWK-016-101, a Phase 1, multicenter, open-label study in adult participants that will employ a sequential dose-escalation and expansion design to evaluate the safety, tolerability, pharmacokinetics and preliminary antitumor activity of HWK-016 in participants with advanced or metastatic solid tumors that are refractory to standard therapies. We expect data readout in the first half of 2027 from HWK-016-101.

HWK-206

Overview

Our product candidate HWK-206 is a biparatopic ADC targeting to two epitopes on the SEZ6 protein. There is limited class competition as we believe ABBV-706 is the only clinical-stage SEZ6 ADC currently in development. We believe our product candidate is the only biparatopic ADC in development for SCLC and NETs patients and that this approach of binding to two independent sites on the target antigen protein will achieve superior outcomes compared to other SCLC ADCs. In vitro and in vivo assays demonstrate increased binding and internalization compared to the monotopic ABBV-706. We plan to complete IND-enabling studies and linker-payload process development in the first half of 2026, with an IND submission planned in mid-2026.

Target Overview: Seizure-related homolog protein 6 (SEZ6)

Seizure-related homolog protein 6 (SEZ6) is a transmembrane protein commonly expressed on neurons, particularly neuronal dendrites, but minimally expressed in normal tissues outside the central nervous system (“CNS”). SEZ6 plays a role in CNS development and maintenance both during childhood development and in adulthood. SEZ6 is responsible for dendritic branching and synapse formation.

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The extracellular portion of the SEZ6 proteins contain three CUB domains and five SCR domains. The presence of multiple CUB and SCR domains suggests potential adhesive or receptor trafficking functions but their binding partners are not yet known.

SEZ6 is highly expressed in about 80% of SCLC and also overexpressed in extrapulmonary NETs and CNS tumors. SEZ6 expression is correlated with tumor progression although its role in cancer is not well understood.

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Whitehawk analysis based on Human Protein Atlas, Gepia, and literature review.

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Emerging Therapies and their Limitations

Currently, we believe ABBV-706 (developed by AbbVie) is the only clinical stage SEZ6 ADC in development. ABBV-706 is a TOP1 inhibitor-based ADC (DAR 6) with a cleavable linker. In a Phase 1 trial in patients with SCLC and neuroendocrine neoplasms (“NEN”), ABBV-706 demonstrated 56% ORR in SCLC at the RP2D of 1.8mg/kg and 37% ORR in NENs. ABBV-706 demonstrated a manageable safety profile with no on-target neurotoxicity. The promising results with ABBV-706 validated SEZ6 as a target and demonstrated clinical improvement by switching to a cleavable TOP1 inhibitor linker-payload. Of note, the most common grade ≥3 treatment-emergent adverse events (“TEAEs”) in the 1.8 mg/kg and 2.5 mg/kg cohorts were hematological and dose-dependent. Adjudicated interstitial lung disease (ILD) of any grade was observed in 7 patients (9%) overall (1.8 mg/kg, n=4; 2.5 mg/kg, n=3), with Grade ≥3 ILD events reported in 4 patients (1.8 mg/kg, n=2; 2.5 mg/kg, =2).

While ABBV‑706 may represent an important advance in the treatment of small cell lung cancer, these findings highlight opportunities for continued innovation in antibody–drug conjugate engineering to further improve safety and tolerability.

Our Product Candidate: HWK-206

We plan to investigate a biparatopic ADC approach for SEZ6. Biparatopic antibodies (which bind two different epitopes of the same protein) can allow for clustering of cells surface receptors by way of binding an epitope of SEZ6 and then a different epitope on another SEZ6 protein. This clustering ultimately results in the formation of large receptor clusters on the cell surface, which can drive receptor internalization and increase payload release for an ADC. We believe this target specificity, binding, and the internalization can translate into great efficacy and/or safety gains for patients treated with ADCs.

Source: Weisser et al. Nat Commun. 2023;14(1):1394.

There are several biparatopic molecules that provide precedent for demonstrating increased therapeutic benefit compared to their single epitope counterparts. For example, zanidatamab, a biparatopic HER2 Ab (Jazz Pharmaceuticals) binds the same epitopes as trastuzumab (Herceptin) and pertuzumab (Perjeta). Zanidatamab demonstrated approximately 20% increase in ORR compared to monoparatopic trastuzumab while maintaining a tolerable safety profile.

We believe our biparatopic SEZ6 ADC, HWK-206, is the only biparatopic ADC in development for SCLC and NETs, and shows potential to outperform the available treatment approaches and the single epitope-binding ADCs in development.

Preclinical models suggest the biSEZ6 antibody shows superior binding and internalization compared to single epitope SEZ6 antibody counterparts, including the antibody used in ABBV-706, with increased mean fluorescence intensity (MFI).

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Clinical Development Plan

We plan to explore this potential in our planned Phase 1 trial in SCLC and NETs where there is a significant need for new treatment options. We plan to complete IND-enabling studies, linker-payload process development and submit an IND in mid-2026.

Intellectual Property

We strive to protect the proprietary technologies that we believe are important to our business, including pursuing and maintaining patent protection intended to cover the ADC Therapies, their respective anticipated methods of use, related technologies, and other inventions that are important to our business. In addition to patent protection, we may also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

Our commercial success will depend, in part, upon our ability to obtain and maintain patent and other proprietary protection for the ADC Therapies, if approved, and other commercially important technologies, inventions, and know-how related to our business, defend and enforce our intellectual property rights, in particular, our patent rights, preserve the confidentiality of our trade secrets, and operate without infringing valid and enforceable intellectual property rights of others.

The patent positions for biotechnology and pharmaceutical companies like us are generally uncertain and can involve complex legal, scientific, and factual issues. We cannot predict whether the patent applications we are currently pursuing will issue as patents in any particular jurisdiction or whether the claims of any issued patents will provide sufficient proprietary protection from competitors. In addition, the coverage claimed in a patent application can be significantly reduced before a patent is issued, and its scope can be reinterpreted and even challenged after issuance. As a result, we cannot guarantee that the ADC Therapies will be protected or remain protectable by enforceable patents. Moreover, any patents that

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we hold may be challenged, circumvented, or invalidated by third parties. For more information regarding the risks related to our intellectual property please see “Risk Factors—Risks Related to Our Intellectual Property”.

The term of individual patents depends upon the legal term of the patents in the countries in which they are obtained. In most countries in which we file, the patent term is 20 years from the earliest date of filing a non-provisional patent application.

In the United States, the term of a patent covering an FDA approved drug may, in certain cases, be eligible for a patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Act, as compensation for the loss of patent term during FDA regulatory review process. The period of extension may be up to five years but cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval. Only one patent among those eligible for an extension and only those claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended. Similar provisions are available in Europe and in certain other jurisdictions to extend the term of a patent that covers an approved drug. We also intend to seek patent term extensions in any jurisdictions where they are available, however, there is no guarantee that the applicable authorities, including the FDA, will agree with our assessment of whether such extensions should be granted, and even if granted, the length of such extensions.

In addition to patent protection, we also rely on trade secret protection for our proprietary information that is not amenable to, or that we do not consider appropriate for, patent protection. However, trade secrets can be difficult to protect. Although we take steps to protect our proprietary information, including restricting access to our premises and our confidential information, as well as entering into agreements with our employees, consultants, advisors, and potential collaborators, such individuals may breach such agreements and disclose our proprietary information including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. In addition, third parties may independently develop the same or similar proprietary information or may otherwise gain access to our proprietary information. As a result, we may be unable to meaningfully protect our trade secrets and proprietary information. For more information regarding the risks related to our intellectual property please see “Risk Factors—Risks Related to Our Intellectual Property.”

As of March 9, 2026, patent rights held by us relating to our ADC drug candidates include the following:

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With respect to the PTK7 targeting drug candidate, our material patents consist of one U.S patent application and related patent applications in Asia and South America exclusively licensed from WuXi Biologics and directed to the PTK7 ADC drug candidate, and two provisional applications which we intend to pursue patent protection for in key jurisdictions. These applications, if issued, are expected to expire in at least 2046, without taking into account any possible patent term adjustments or extensions and assuming payment of all appropriate maintenance, renewal, annuity or other governmental fees.

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With respect to the SEZ6 targeting drug candidate, our material patents consist of patent applications in Asia and South America exclusively licensed from WuXi Biologics and directed to the SEZ6 ADC drug candidate, which we intend to pursue patent protection for in key jurisdictions. These applications, if issued, is expected to expire in at least 2046, without taking into account any possible patent term adjustments or extensions and assuming payment of all appropriate maintenance, renewal, annuity or other governmental fees.

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With respect to the MUC16 targeting drug candidate, our material patents consist of one U.S patent application and related patent applications in Asia and South America exclusively licensed from WuXi Biologics and directed to the MUC16 ADC drug candidate and one U.S. provisional application, which we intend to pursue patent protection for in key jurisdictions. These applications, if issued, are expected to expire in at least 2046, without taking into account any possible patent term adjustments or extensions and assuming payment of all appropriate maintenance, renewal, annuity or other governmental fees.

Competition

Many companies are active in the oncology market and are developing or marketing products for the specific therapeutic markets that we target, including both antibody- and non-antibody-based therapies. Similarly, we also face competition from other companies and institutions that continue to invest in innovation in the ADC field, including new payload classes, new conjugation approaches and new targeting moieties. Specifically, we are aware of multiple companies with ADC technologies that may be competitive with our products and product candidates, including, but not limited to, AbbVie, Daiichi Sankyo, Day One Biopharmaceuticals, Eli Lilly, Genmab, GlaxoSmithKline, Gilead, Kelun, Mersana, Sanofi, Roche, Pfizer,

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Zymeworks, Ideaya and Biocytogen. There are hundreds of ADCs in development, the vast majority of which are being developed for the treatment of cancer.

Our industry is characterized by rapidly advancing technologies, intense competition, and a strong emphasis on proprietary products. We face competition with respect to our current products and product candidates and will face competition with respect to any products and product candidates that we may seek to develop or commercialize in the future. Our competitors include large pharmaceutical and biotechnology companies, academic institutions, government agencies and other public and private research organizations that conduct research, seek patent protection and establish collaborative arrangements for research, development, manufacturing and commercialization. Many of our competitors have significantly greater financial resources and capabilities in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approval and marketing than we do. Furthermore, mergers and acquisitions in the biotechnology industry may result in even more resources being concentrated among a smaller number of our competitors.

In addition, we expect changes to the treatment paradigm, including potential new entrants and new approvals across the lines of therapies. New technologies, procedures or treatments could change the patient population and their eligibility to use our product candidates, raise expectations regarding safety and efficacy results that are necessary for regulatory approval and, if approved, adoption by the medical community, or otherwise render the ADC Therapies and any other product candidates that we may develop obsolete.

PTK7

Although there are currently no approved ADCs targeting PTK7, there are multiple PTK7 programs currently in, or about to begin, clinical development, including

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DAY301 (MTX-13), being developed by Day One Biopharmaceuticals after acquiring development and commercialization rights outside of the Greater China area from MabCare Therapeutics, is being explored in a Phase 1 trial.

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LY4175408, being developed by Eli Lilly, also has a pure exatecan payload and is being explored in a Phase 1 trial.

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SKB518, being developed by Kelun Biotech, is currently in Phase 1 in China.

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KIVU-107, being developed by Kivu Bioscience, uses a pure exatecan payload and is being explored in a Phase 1 trial.

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IDE034, being developed by Ideaya Biosciences, an investigational PTK7/B7H3 bispecific TOP1 ADC being explored in a Phase 1 trial.

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Additionally, there are multiple preclinical PTK7 bispecific ADCs in development.

In addition, there are multiple PTK7 ADC programs that are projected to present clinical data in 2026 and 2027, which we believe will further validate our target and TOP1 inhibitor payload approach.

MUC16

Currently, there are no approved ADCs targeting MUC16. Regeneron is developing two MUC16 bispecific T cell-engaging antibodies; a limitation of this approach, however, includes the modest ORRs observed to date. While several ADCs targeting other antigens in PROC are under development, none offer the combined advantages of high target expression in both depth and frequency, along with the potential for a matched blood-based biomarker like CA125. In addition, there are several early-stage clinical trials evaluating CART cell therapies targeting MUC16.

SEZ6

Currently, we believe ABBV-706 (developed by AbbVie) is the only clinical stage SEZ6 ADC in development. ABBV-706 is a TOP1 inhibitor-based ADC (DAR 6) with a cleavable linker. In a Phase 1 trial in patients with SCLC and neuroendocrine neoplasms (“NEN”), ABBV-706 demonstrated 56% ORR in SCLC and 37% ORR in NENs. ABBV-706 demonstrated a manageable safety profile with no on-target neurotoxicity. The promising results with ABBV-706 validated SEZ6 as a target and demonstrated clinical improvement by switching to a cleavable TOP1 inhibitor linker-payload.

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Manufacturing

We do not own or operate, and have no plans to establish, any manufacturing facilities. We continue to benefit from the continuity of partnership with WuXi Biologics and its affiliates and Hangzhou DAC for ADC manufacturing for our clinical supply pursuant to a master services agreement and material supply agreement, respectively, and corresponding work orders. We will expand our CRDMO network as appropriate as our portfolio advances further in clinical trials.

Government Regulation

Government authorities in the United States, including federal, state, and local authorities, and in other countries, extensively regulate, among other things, the manufacturing, research and clinical development, marketing, labeling and packaging, storage, distribution, post-approval monitoring and reporting, advertising and promotion, and export and import of pharmaceutical and biological products, such as those we are developing. In addition, some government authorities regulate the pricing of such products. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local and foreign statutes and regulations require the expenditure of substantial time and financial resources.

U.S. Government Regulation

Government authorities in the United States, at the federal, state, and local level, and other countries extensively regulate, among other things, the research, development, nonclinical and clinical testing, manufacture, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, post-approval monitoring and reporting, marketing, and export and import of products such as those we are developing.

Generally, before a new drug can be marketed, considerable data must be generated which demonstrate the drug’s quality, safety, and efficacy. Such data must then be organized into a format specific for each regulatory authority, submitted for review and approved by the regulatory authority.

Drugs are also subject to other federal, state, and local statutes and regulations. The process of obtaining regulatory approvals and the subsequent compliance with appropriate federal, state, local, and foreign statutes and regulations require the expenditure of substantial time and financial resources. Failure to comply with the applicable regulatory requirements at any time during the product development process, approval process, or after approval, may subject an applicant to administrative or judicial sanctions. These sanctions could include, among other actions, the regulatory authority’s refusal to approve pending applications, withdrawal of an approval, clinical holds, untitled or warning letters, voluntary product recalls or withdrawals from the market, product seizures, total or partial suspension of production or distribution, injunctions, debarment, fines, refusals of government contracts, restitution, disgorgement, or civil or criminal penalties. Any agency or judicial enforcement action could have a material adverse effect on us.

U.S. Drug Development

In the U.S., the FDA regulates drugs under the Federal Food, Drug, and Cosmetic Act (“FDCA”) and its implementing regulations. Drugs are also subject to other federal, state, and local statutes and regulations. Drugs must be approved by the FDA through the NDA process before they may be legally marketed in the U.S. The process required by the FDA before a drug may be marketed in the U.S. generally involves the following:

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completion of extensive preclinical, sometimes referred to as nonclinical, laboratory tests, animal studies, and formulation studies all performed in accordance with applicable regulations, including the FDA’s good laboratory practice (“GLP”) regulations;

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submission to the FDA of an investigational new drug application (“IND”), which must become effective before human clinical trials may begin and must be updated annually and amended in accordance with the regulations;

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performance of adequate and well-controlled human clinical trials in accordance with applicable IND and other clinical trial-related regulations, sometimes referred to as good clinical practices (“GCPs”), to establish the safety and efficacy of the proposed drug for its proposed indication(s);

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submission to the FDA of an NDA for a new drug;

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a determination by the FDA within 60 days of its receipt of an NDA to file the NDA for review;

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satisfactory completion of an FDA pre-approval inspection of the manufacturing facility or facilities at which the active pharmaceutical ingredient (“API”) and finished drug product are produced to assess compliance with the FDA’s current good manufacturing practice requirements (“cGMP”);

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potential FDA audit of the testing laboratories and clinical trial sites that generated the data in support of the NDA; and

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FDA review and approval of the NDA prior to any commercial marketing or sale of the drug in the U.S.

Prior to beginning a clinical trial with a product candidate in the United States, companies must submit an IND to the FDA. An IND is a request for authorization from the FDA to administer an investigational new drug product to humans. The central focus of an IND submission is on the general investigational plan and the protocol(s) for clinical studies. The IND also includes results of animal and in vitro studies assessing the toxicology, pharmacokinetics, pharmacology, and pharmacodynamic characteristics of the product; chemistry, manufacturing, and controls information; and any available human data or literature to support the use of the investigational product. An IND must become effective before human clinical trials may begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day time period, raises safety concerns or questions about the proposed clinical trial. In such a case, the IND may be placed on clinical hold and the IND sponsor and the FDA must resolve any outstanding concerns or questions before the clinical trial can begin. Submission of an IND therefore may or may not result in FDA authorization to begin a clinical trial.

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with GCPs, which include the requirement that all research subjects provide their informed consent for their participation in any clinical study. Clinical trials are conducted under protocols detailing, among other things, the objectives of the study, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated. A new IND, or a separate submission to the existing IND must be made for each successive clinical trial conducted during product development and for any subsequent protocol amendments. Furthermore, an independent review board ("IRB") for each site proposing to conduct the clinical trial must review and approve the plan for any clinical trial and its informed consent form before the clinical trial begins at that site and must monitor the study until completed. Regulatory authorities, the IRB or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the clinical trial is unlikely to meet its stated objectives. Some studies also include oversight by an independent group of qualified experts organized by the clinical study sponsor, known as a data safety monitoring board, which may review data and endpoints at designated check points, make recommendations and/or halt the clinical trial if it determines that there is an unacceptable safety risk for subjects or other grounds, such as no demonstration of efficacy. There are also requirements governing the reporting of ongoing clinical studies and clinical study results to public registries.

Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

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Phase 1: The product candidate is initially introduced into healthy human subjects or patients with the target disease or condition. These studies are designed to test the safety, dosage tolerance, absorption, metabolism and distribution of the investigational product in humans, the side effects associated with increasing doses, and, if possible, to gain early evidence on effectiveness. In the case of some products for severe or life-threatening diseases, especially when the product may be too inherently toxic to ethically administer to healthy volunteers, the initial human testing is often conducted in patients.

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Phase 2: The product candidate is administered to a limited patient population with a specified disease or condition to evaluate the preliminary efficacy, optimal dosages, and dosing schedule and to identify possible adverse side effects and safety risks. Multiple Phase 2 clinical trials may be conducted to obtain information prior to beginning larger and more expensive Phase 3 clinical trials.

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Phase 3: The product candidate is administered to an expanded patient population to further evaluate dosage, to provide statistically significant evidence of clinical efficacy and to further test for safety, generally at multiple

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geographically dispersed clinical trial sites. These clinical trials are intended to establish the overall risk/benefit ratio of the investigational product and to provide an adequate basis for product approval.

A pivotal study is a clinical study that adequately meets regulatory agency requirements for the evaluation of a drug candidate’s efficacy and safety such that it can serve as the primary basis for approval of the drug. Generally, pivotal studies are also Phase 3 studies but may be Phase 2 studies if the trial design provides a well-controlled and reliable assessment of clinical benefit, particularly in situations where there is an unmet medical need. Post-approval trials, sometimes referred to as Phase 4 clinical trials, 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. In certain instances, the FDA may mandate the performance of Phase 4 clinical trials.

Progress reports detailing the results of the clinical trials must be submitted at least annually to the FDA and written IND safety reports must be submitted to the FDA and the investigators for serious and unexpected adverse reactions, any finding from other clinical studies, tests in laboratory animals, or in vitro testing that suggests a significant risk for human subjects, or 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 submit an IND safety report within 15 calendar days after the sponsor determines that the information qualifies for reporting. The sponsor also must notify the FDA of any unexpected fatal or life-threatening suspected adverse reaction within seven calendar days after the sponsor’s initial receipt of the information. Phase 1, Phase 2, and Phase 3 trials may not be completed successfully within any specified period, if at all. The FDA, the IRB, or the clinical trial sponsor may suspend or terminate a clinical trial at any time on various grounds, including a finding that the research subjects or patients are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the drug has been associated with unexpected serious harm to patients.

We may also suspend or terminate a clinical trial based on evolving business objectives and/or competitive climate. Concurrent with clinical trials, companies usually complete additional animal studies and must also develop additional information about the chemistry and physical characteristics of the drug as well as finalize a process for manufacturing the drug in commercial quantities in accordance with cGMP requirements. The manufacturing process must be capable of consistently producing quality batches of the drug candidate and, among other things, cGMPs impose extensive procedural, substantive, and recordkeeping requirements to ensure and preserve the long-term stability and quality of the final drug product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the drug candidate does not undergo unacceptable deterioration over its shelf life.

A manufacturer of an investigational drug for a serious disease or condition is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for individual patient access to such investigational drug. This requirement applies on the earlier of the first initiation of a Phase 2 or Phase 3 trial of the investigational drug or, as applicable, 15 days after the drug receives a designation as a breakthrough therapy, fast track product, or regenerative advanced therapy.

NDA and the FDA Review Process

Following trial completion, trial data are analyzed to assess safety and efficacy. The results of preclinical studies and clinical trials are then submitted to the FDA as part of an NDA, along with proposed labeling for the drug and information about the manufacturing process and facilities that will be used to ensure drug quality, results of analytical testing conducted on the chemistry of the drug, and other relevant information. The NDA is a request for approval to market the drug and must contain sufficient evidence of drug product quality, safety and efficacy, which is demonstrated by extensive analytical, preclinical and clinical testing. Data may come from company-sponsored clinical trials intended to test the safety and efficacy of a use of a drug, 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 drug product for a particular indication or indications to the satisfaction of the FDA. FDA approval of an NDA must be obtained before a drug may be offered for sale in the United States.

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The submission of an NDA is subject to the payment of substantial user fees; a waiver of such fees may be obtained under certain limited circumstances. 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 reviews an NDA to determine, among other things, whether a product is safe and effective for its intended use and whether its manufacturing is cGMP-compliant to assure and preserve the product’s identity, strength, quality, and purity. Under the Prescription Drug User Fee Act (PDUFA) guidelines that are currently in effect, the FDA has a goal of ten months from the date of “filing” of a standard NDA for a new molecular entity to review and act on the submission. This review typically takes 12 months from the date the NDA is submitted to FDA because the FDA has approximately two months to make a “filing” decision after the application is submitted. The FDA conducts a preliminary review of all NDAs within the first 60 days after submission, before accepting them for filing, to determine whether they are sufficiently complete to permit substantive review. The FDA does not always meet its PDUFA goal dates for standard and priority NDAs, and the review process is often significantly extended by FDA requests for additional information or clarification. In such event, the NDA must be resubmitted with the additional information. The resubmitted application is also subject to review before the FDA accepts it for filing.

After the NDA submission is accepted for filing, the FDA reviews the NDA to determine, among other things, whether the proposed drug is safe and effective for its intended use, and whether the drug is being manufactured in accordance with cGMP to assure and preserve the drug’s identity, strength, quality, and purity. The FDA may refer applications for novel drugs or drug candidates that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation, and a recommendation 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. In the course of its review, the FDA may re-analyze the clinical trial data, which could result in extensive discussions between the FDA and the applicant during the review process. The review and evaluation of an NDA by the FDA is extensive and time consuming and may take longer than originally planned to complete, and we may not receive a timely approval, if at all.

Before approving an NDA, the FDA typically conducts a pre-approval inspection of the manufacturing facilities for the new drug to determine whether they comply with cGMPs. The FDA will not approve the drug unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the drug within required specifications. In addition, before approving an NDA, the FDA may also audit data from clinical trials to ensure compliance with GCP requirements. After the FDA evaluates the application, manufacturing process, and manufacturing facilities where the drug product and/or its API will be produced, it may issue an approval letter or a Complete Response Letter. An approval letter authorizes commercial marketing of the drug with specific prescribing information for specific indications. A Complete Response Letter indicates that the review cycle of the application is complete and the application is not ready for approval. A Complete Response Letter usually describes all of the specific deficiencies in the NDA identified by the FDA. The Complete Response Letter may require additional clinical data and/or an additional pivotal clinical trial(s), and/or other significant, expensive and time-consuming requirements related to clinical trials, preclinical studies, or manufacturing. If a Complete Response Letter is issued, the applicant may either resubmit the NDA, addressing all of the deficiencies identified in the letter, challenge the determination set forth in the letter by requesting a hearing, or withdraw the application. Even if such data and information are submitted, the FDA may ultimately decide that the NDA does not satisfy the criteria for approval. Data obtained from clinical trials are not always conclusive and the FDA may interpret data differently than we interpret the same data. Further, FDA’s “real time” release of newly issued Complete Response Letters associated with withdrawn or abandoned applications, if applicable to any of our product candidates, can materially impact our business and competitive advantage.

There is no assurance that the FDA will ultimately approve a drug product for marketing in the United States and we may encounter significant difficulties or costs during the review process. If a drug receives marketing approval, the approval may be significantly limited to specific diseases, dosages, or patient subgroups, or the indications for use may otherwise be limited, which could restrict the commercial value of the drug. Further, the FDA may require that certain contraindications, warnings, precautions, or adverse events be included in the drug labeling or may condition the approval of the NDA on other changes to the proposed labeling, development of adequate controls and specifications, or a commitment to conduct post-marketing testing or clinical trials, and surveillance to monitor the effects of approved drugs.

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If regulatory approval of a product is granted, such approval will be granted for particular indications and may entail limitations on the indicated uses for which such product may be marketed. For example, the FDA may approve the NDA with a Risk Evaluation and Mitigation Strategy (“REMS”) to ensure the benefits of the product outweigh its risks. A REMS is a safety strategy to manage a known or potential serious risk associated with a medicine and to enable patients to have continued access to such medicines by managing their safe use. It could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries, and other risk minimization tools.

Once approved, the FDA may withdraw the product approval if compliance with pre- and post-marketing requirements is not maintained or if problems occur after the product reaches the marketplace. The FDA may also require one or more Phase 4 post-market studies and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization and may limit further marketing of the product based on the results of these post-marketing studies. In addition, new government requirements, including those resulting from new legislation, may be established, or the FDA’s policies may change, which could impact the timeline for regulatory approval or otherwise impact ongoing development programs.

Any of these limitations on approval or marketing could restrict the commercial promotion, distribution, prescription, or dispensing of drugs. Drug approvals may be withdrawn for non-compliance with regulatory standards or if problems occur following initial marketing.

FDA Expedited Development and Review Programs

The FDA has various programs, including fast track designation, priority review, accelerated approval, and breakthrough therapy designation, which are intended to expedite or simplify the process for the development and FDA review of drugs that are intended for the treatment of serious or life-threatening diseases or conditions and demonstrate the potential to address unmet medical needs. The purpose of these programs is to provide important new drugs to patients earlier than under standard FDA review procedures.

The FDA has a fast track designation program that is intended to expedite or facilitate the process for reviewing new drug products that meet certain criteria. Specifically, new drugs are eligible for fast track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. With regard to a fast track product, the FDA may consider for review sections of the NDA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the NDA, the FDA agrees to accept sections of the NDA and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the NDA.

Any product submitted to the FDA for approval, including a product with a fast track designation, may also be eligible for other types of FDA programs intended to expedite development and review, such as priority review and accelerated approval. A product is eligible for priority review if it has the potential to provide safe and effective therapy where no satisfactory alternative therapy exists or a significant improvement in the treatment, diagnosis, or prevention of a disease compared to marketed products. The FDA will attempt to direct additional resources to the evaluation of an application for a new drug designated for priority review in an effort to facilitate the review. The FDA endeavors to review applications with priority review designations within six months of the filing date as compared to ten months for review of new molecular entity NDAs under its current PDUFA review goals.

In addition, a product may be eligible for accelerated approval. Drug products intended to treat serious or life-threatening diseases or conditions may be eligible for accelerated approval upon a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, that 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. As a condition of approval, the FDA may require a sponsor of a drug receiving accelerated approval to perform post-marketing studies to verify and describe the predicted effect on irreversible morbidity or mortality, or other clinical endpoint and to submit promotional materials for preapproval and pre-use review, which could adversely impact the timing of the commercial launch of the product. In addition, the drug may be subject to accelerated withdrawal procedures.

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The Food and Drug Omnibus Reform Act made several changes to the FDA’s authorities and its regulatory framework, including, among other changes, reforms to the accelerated approval pathway, such as requiring the FDA to specify conditions for post-approval study requirements and setting forth procedures for the FDA to withdraw a product on an expedited basis for non-compliance with post-approval requirements.

The Food and Drug Administration Safety and Innovation Act established a category of drugs referred to as “breakthrough therapies” that may be eligible to receive breakthrough therapy designation. A sponsor may seek FDA designation of a product candidate as a “breakthrough therapy” if the product is intended, alone or in combination with one or more other products, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the fast track program features, as well as more intensive FDA interaction and guidance. The breakthrough therapy designation is a distinct status from both accelerated approval and priority review, which can also be granted to the same drug if relevant criteria are met. If a product is designated as breakthrough therapy, the FDA will work to expedite the development and review of such drug.

In addition, the FDA may review new drug applications under the Oncology Center of Excellence Real-Time Oncology Review (“RTOR”), which, according to the FDA, aims to explore a more efficient review process to ensure that safe and effective treatments are available to patients as early as possible, while maintaining and improving review quality. Drugs considered for review under RTOR must be likely to demonstrate substantial improvements over available therapy, which may include drugs previously granted breakthrough therapy designation for the same or other indications, and must have straight-forward study designs and endpoints that can be easily interpreted. RTOR allows the FDA to review much of the data in an NDA earlier, before the applicant formally submits the complete application. This analysis of the pre-submission package gives the FDA and applicants an early opportunity to address data quality and potential review issues and allows the FDA to provide early feedback regarding the most effective way to analyze data to properly address key regulatory questions.

Fast track designation, priority review, accelerated approval, and breakthrough therapy designation do not change the standards for approval, but may expedite the development or approval process. 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 decide that the time period for FDA review or approval will not be shortened. We may explore some of these opportunities for the ADC Therapies as appropriate.

Post-Marketing Requirements

Following approval of a new drug, a pharmaceutical company and the approved drug are subject to continuing regulation by the FDA, including, among other things, establishment registration and drug listing, monitoring and recordkeeping activities, reporting to the applicable regulatory authorities of adverse experiences with the drug, providing the regulatory authorities with updated safety and efficacy information, drug sampling and distribution requirements, and complying with promotion and advertising requirements, which include, among others, standards for direct-to-consumer advertising, restrictions on promoting drugs for uses or in patient populations that are not described in the drug’s approved labeling, limitations on industry-sponsored scientific and educational activities, and requirements for promotional activities involving the internet.

In particular, the FDA closely regulates the marketing, labeling, advertising, and promotion of drug products. A company can make only those claims relating to safety and efficacy that are approved by the FDA and in accordance with the provisions of the approved label. The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses. Failure to comply with these requirements can result in, among other things, adverse publicity, warning letters, corrective advertising, and potential civil and criminal penalties. Physicians may prescribe, in their independent professional medical judgment, legally available products for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Physicians may believe that such off-label uses are the best treatment for many patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use of their products. The federal government has levied large civil and criminal fines against companies for alleged improper promotion of off-label use and has enjoined companies from engaging in off-label promotion. The FDA and other regulatory agencies have also required that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed. However, companies may share truthful and not misleading information that is otherwise consistent with a

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product’s FDA-approved labelling. Modifications or enhancements to the drug or its labeling or changes of the site or process of manufacture are often subject to the approval of the FDA and other regulators, which may or may not be received or may result in a lengthy review process.

Prescription drug advertising is subject to federal, state, and foreign regulations. In the U.S., the FDA regulates prescription drug promotion, including direct-to-consumer advertising. Prescription drug promotional materials must be submitted to the FDA in conjunction with their first use. Any distribution of prescription drugs and pharmaceutical samples must comply with the U.S. Prescription Drug Marketing Act (“PDMA”), a part of the FDCA. Drug manufacturers and their collaborators are also required to place a unique product identifier on prescription drug packages. This identifier consists of the National Drug Code, serial number, lot number, and expiration date, in the form of a 2-dimensional data matrix barcode that can be read by humans and machines.

In the U.S., once a drug is approved, its manufacture is subject to comprehensive and continuing regulation by the FDA. FDA regulations require that drugs be manufactured in specific facilities per the NDA approval and in accordance with cGMP. We rely, and expect to continue to rely, on third parties for the production of clinical and commercial quantities of its drugs in accordance with cGMP regulations. cGMP regulations require among other things, quality control and quality assurance as well as the corresponding maintenance of records and documentation and the obligation to investigate and correct any deviations from cGMP. Drug manufacturers and other entities involved in the manufacture and distribution of approved drugs 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 cGMP and other laws. Accordingly, manufacturers must continue to expend time, money, and effort in the area of production and quality control to maintain cGMP compliance. These regulations also impose certain organizational, procedural, and documentation requirements with respect to manufacturing and quality assurance activities. NDA holders using contract manufacturers, laboratories or packagers are responsible for the selection and monitoring of qualified firms, and, in certain circumstances, qualified suppliers to these firms. These firms and, where applicable, their suppliers are subject to inspections by the FDA at any time, and the discovery of violative conditions, including failure to conform to cGMP, could result in enforcement actions that interrupt the operation of any such facilities or the ability to distribute drugs manufactured, processed, or tested by them. Discovery of problems with a drug after approval may result in restrictions on a drug, manufacturer, or holder of an approved NDA, including, among other things, recall or withdrawal of the drug from the market, and may require substantial resources to correct.

The FDA also may require post-approval testing, sometimes referred to as Phase 4 testing, risk minimization action plans, and post- marketing surveillance to monitor the effects of an approved drug or place conditions on an approval that could restrict the distribution or use of the drug. Discovery of previously unknown problems with a drug or the failure to comply with applicable FDA requirements can have negative consequences, including adverse publicity, judicial, or administrative enforcement actions. Other potential consequences include, among other things:

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restrictions on the marketing or manufacturing of the product, complete withdrawal of the product from the market or product recalls;

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fines, warning letters, or untitled letters;

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clinical holds on post-approval or Phase 4 clinical studies, if applicable;

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refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of product license approvals;

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product seizure or detention, or refusal to permit the import or export of products;

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consent decrees, corporate integrity agreements, debarment, or exclusion from federal healthcare programs;

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mandated modification of promotional materials and labeling and the issuance of corrective information;

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the issuance of safety alerts, Dear Healthcare Provider letters, press releases, and other communications containing warnings or other safety information about the product; or

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injunctions or the imposition of civil or criminal penalties.

The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Newly discovered or developed safety or effectiveness data may require changes to a drug’s approved labeling, including the addition of new warnings and contraindications, and also may require the implementation of other risk management measures, including a REMS or the conduct of post-marketing studies to assess a newly discovered safety issue. Also, new government requirements, including those resulting from new legislation, may be established, or the FDA’s policies may change, which could delay or prevent regulatory approval of our drugs under development.

Orphan Drug Designation

The FDA may grant orphan drug designation to drugs intended to treat a rare disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States, there is no reasonable expectation that the cost of developing and marketing the drug for this type of disease or condition will be recovered from sales in the United States. Orphan drug designation must be requested before submitting an application for marketing approval. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process. After the grant of an orphan drug designation, FDA may revoke the designation if FDA finds that the request for designation contained an untrue statement of material fact, omitted required material information, or if FDA subsequently finds that the drug had not been eligible for the orphan drug designation at the time of the submission of the request.

In the United States, orphan drug designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages, and user-fee waivers. In addition, if a product receives the first FDA approval for the indication for which it has orphan designation, the product is entitled to orphan drug exclusivity ("ODE"), which means the FDA may not approve any other application to market the same drug for the same indication for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity.

In Catalyst Pharms., Inc. v. Becerra, 14 F.4th 1299 (11th Cir. 2021), the court disagreed with the FDA’s longstanding position that the ODE only applies to the approved use or indication within an eligible disease. This decision created uncertainty in the application of the ODE. On January 24, 2023, the FDA published a notice in the Federal Register to clarify that while the agency complies with the court’s order in Catalyst, FDA intends to continue to apply its longstanding interpretation of the regulations to matters outside of the scope of the Catalyst order – that is, the agency will continue tying the scope of ODE to the uses or indications for which a drug is approved, which permits other sponsors to obtain approval of a drug for new uses or indications within the same orphan designated disease or condition that have not yet been approved. It is unclear how future litigation, legislation, agency decisions, and administrative actions will impact the scope of the ODE. The Consolidated Appropriations Act of 2026, signed into law in February 2026, codified this longstanding FDA interpretation of the Orphan Drug Act, allowing the FDA to approve multiple versions of the same orphan drug for different subindications and subpopulations.

In June 2024, in Loper Bright Enterprises v. Raimondo, the U.S. Supreme Court overruled the Chevron doctrine, which gave deference to regulatory agencies’ statutory interpretations in litigation against federal government agencies, such as the FDA, where the law is ambiguous. This landmark Supreme Court decision may invite various stakeholders to bring lawsuits against the FDA to challenge longstanding decisions and policies, which could lead to uncertainties in the industry. Further, changes in the leadership of the FDA and other federal agencies under the current administration may lead to new policies, changes in the regulations, or disruptions to the operations of federal agencies, any of which may impact our clinical development plans.

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In the European Union, the European Commission, after receiving the opinion of the European Medicines Agency’s (“EMA”) Committee for Orphan Medicinal Products (“COMP”), grants orphan drug designation to also promote the development of products. The relevant European legislation provides that a product can be designated as an orphan drug by the European Commission if its sponsor can establish: that the product is intended for the diagnosis, prevention, or treatment of (1) a life-threatening or chronically debilitating condition affecting not more than 5 in 10,000 persons in the European Union when the application is made, or (2) a life-threatening, seriously debilitating, or serious and chronic condition in the European Union and that without incentives it is unlikely that the marketing of the product in the European Union would generate sufficient return to justify the necessary investment. For either of these conditions, the applicant must also demonstrate that there exists no satisfactory method of diagnosis, prevention, or treatment of the condition in question that has been authorized in the European Union or, if such method exists, the product has to be of significant benefit compared to products available for the condition. Additionally, designation is granted for products intended for the diagnosis, prevention, or treatment of a life-threatening, seriously debilitating, or serious and chronic condition and when, without incentives, it is unlikely that sales of the drug in the European Union would be sufficient to justify the necessary investment in developing the drug or biological product.

In the European Union, orphan drug designation also entitles a party to financial incentives such as reduction of fees or fee waivers and ten years of market exclusivity is granted following drug or biological product approval. During this market exclusivity period, neither the EMA nor the European Commission or the 27 member states that comprise the European Union can accept an application or grant a marketing authorization for the same therapeutic indication in respect of a “similar medicinal product.” 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. This period may be reduced to six years if, after five years, the orphan drug designation criteria are no longer met, including where it is shown that the product is sufficiently profitable not to justify maintenance of market exclusivity.

U.S. Patent Term Restoration and Marketing Exclusivity

Depending upon the timing, duration, and specifics of the FDA approval of our ADC drug candidate, some of our United States patents may be eligible for limited patent term extension under the Hatch-Waxman Act. The Hatch-Waxman Act permits a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of a patent beyond a total of 14 years from the product’s approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and the submission date of an NDA plus the time between the submission date of an NDA and the approval of that application. The U.S. Patent and Trademark Office (“USPTO”), in consultation with the FDA, reviews and approves the application for any patent term extension or restoration.

Marketing exclusivity provisions under the FDCA can also delay the submission or the approval of certain marketing applications for competing products. The FDCA provides a five-year period of non-patent marketing exclusivity within the U.S. to the first applicant to obtain approval of an NDA for a new chemical entity. A drug is a new chemical entity if the FDA has not previously approved any other new drug containing the same active moiety, which is the molecule or ion responsible for the action of the drug substance. During the exclusivity period, the FDA may not accept for review an abbreviated new drug application (“ANDA”) or a 505(b)(2) NDA submitted by another company for another drug based on the same active moiety, regardless of whether the drug is intended for the same indication as the original innovator drug or for another indication. However, an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement to one of the patents listed with the FDA by the innovator NDA holder.

The FDCA also provides three years of marketing exclusivity for an NDA, or supplement to an existing NDA, if new clinical investigations, other than bioavailability studies, that were conducted or sponsored by the applicant are deemed by the FDA to be essential to the approval of the application, for example new indications, dosages, or strengths of an existing drug. This three-year exclusivity covers only the modification for which the drug received approval on the basis of the new clinical investigations and does not prohibit the FDA from approving ANDAs or 505(b)(2) applications for drugs containing the active agent for the original indication or condition of use.

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These five-year and three-year exclusivities will not delay the submission or approval of a full NDA. However, an applicant submitting a full NDA would be required to conduct or obtain a right of reference to all of the preclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and effectiveness.

ODE, as described above, may offer a seven-year period of marketing exclusivity, except in certain circumstances. Pediatric exclusivity is another type of regulatory 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 in accordance with an FDA-issued “Written Request” for a pediatric trial.

Other U.S. Regulatory Matters

Manufacturing, sales, promotion, and other activities following drug approval are also subject to regulation by numerous regulatory authorities in addition to the FDA, including, in the United States, the Centers for Medicare & Medicaid Services (“CMS”), other divisions of the U.S. Department of Health and Human Services (“HHS”), the Drug Enforcement Administration for controlled substances, the Consumer Product Safety Commission, the Federal Trade Commission, the Occupational Safety & Health Administration, the Environmental Protection Agency, and state and local governments. In the United States, sales, marketing, and scientific/educational programs must also comply with state and federal fraud and abuse laws. Pricing and rebate programs must comply with the Medicaid rebate requirements of the U.S. Omnibus Budget Reconciliation Act of 1990 and more recent requirements in the Patient Protection and Affordable Care Act as amended by the Health Care and Education Reconciliation Act of 2010 (the “ACA”). If drugs are made available to authorized users of the Federal Supply Schedule of the General Services Administration, additional laws and requirements apply. The handling of any controlled substances must comply with the U.S. Controlled Substances Act and Controlled Substances Import and Export Act. Drugs must meet applicable child-resistant packaging requirements under the U.S. Poison Prevention Packaging Act. Manufacturing, sales, promotion, and other activities are also potentially subject to federal and state consumer protection and unfair competition laws.

We are subject to numerous foreign, federal, state, and local 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. In addition, our leasing and operation of real property may subject us to liability pursuant to certain U.S. environmental laws and regulations, under which current or previous owners or operators of real property and entities that disposed or arranged for the disposal of hazardous substances may be held strictly, jointly, and severally liable for the cost of investigating or remediating contamination caused by hazardous substance releases, even if they did not know of and were not responsible for the releases.

The distribution of pharmaceutical drugs is subject to additional requirements and regulations, including extensive record-keeping, licensing, storage, and security requirements intended to prevent the unauthorized sale of pharmaceutical drugs. The failure to comply with regulatory requirements subjects firms to possible legal or regulatory action. Depending on the circumstances, failure to meet applicable regulatory requirements can result in criminal prosecution, fines, or other penalties, injunctions, voluntary recall or seizure of drugs, total or partial suspension of production, denial or withdrawal of product approvals, or refusal to allow a firm to enter into supply contracts, including government contracts. In addition, even if a firm complies with FDA and other requirements, new information regarding the safety or efficacy of a product could lead the FDA to modify or withdraw product approval. Prohibitions or restrictions on 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; (iii) the recall or discontinuation of our products; or (iv) additional record-keeping requirements. If any such changes were to be imposed, they could adversely affect the operation of our business.

Coverage and Reimbursement

Sales of our drugs will depend, in part, on the extent to which our drugs will be covered by third-party payors, such as government health programs, commercial insurers, and managed healthcare organizations, as well as the level of reimbursement such third-party payors provide for our products. Patients and providers are unlikely to use our products

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unless coverage is provided and reimbursement is adequate to cover a significant portion of the cost of our products in which our products are used. These third-party payors are increasingly reducing reimbursements for medical drugs and services.

In the U.S., no uniform policy of coverage and reimbursement for drugs or biological products exists, and one payor’s determination to provide coverage and adequate reimbursement for a product does not assure that other payors will make a similar determination. In the U.S., the principal decisions about reimbursement for new medicines are typically made by the CMS, an agency within the HHS, as the CMS decides whether and to what extent a new medicine will be covered and reimbursed under Medicare. Private third-party payors tend to follow Medicare coverage and reimbursement limitations to a substantial degree, but also have their own methods and approval process apart from Medicare determinations. Accordingly, decisions regarding the extent of coverage and amount of reimbursement to be provided for the ADC Therapies will be made on a payor-by-payor basis. As a result, the coverage determination process may be a time-consuming and costly process that will require us to provide scientific and clinical support for the use of our products to each payor separately, with no assurance that coverage and adequate reimbursement will be obtained. Even if we obtain coverage for a given product, the resulting reimbursement payment rates might not be adequate for us to achieve or sustain profitability or may require co-payments that patients find unacceptably high.

Additionally, the containment of healthcare costs has become a priority of federal and state governments, and the prices of drugs have been a focus in this effort. The U.S. government, state legislatures, and foreign governments have shown significant interest in implementing cost-containment programs, including price controls, restrictions on reimbursement, and requirements for substitution of generic drugs. Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit our net revenue and results.

The Medicaid Drug Rebate Program (“MDRP”) requires pharmaceutical manufacturers to enter into and have in effect a national rebate agreement with the Secretary of the HHS as a condition for states to receive federal matching funds for the manufacturer’s outpatient drugs furnished to Medicaid patients. The ACA made several changes to the MDRP, including increasing pharmaceutical manufacturers’ rebate liability by raising the minimum basic Medicaid rebate percentage on most branded prescription drugs of average manufacturer price (“AMP”) and adding a new rebate calculation for “line extensions” (i.e., new formulations, such as extended release formulations) of solid oral dosage forms of branded products, creating a new methodology by which rebates owed are calculated for drugs that are inhaled, infused, instilled, implanted, or injected, as well as potentially impacting their rebate liability by modifying the statutory definition of AMP. The ACA also expanded the universe of Medicaid utilization subject to drug rebates by requiring pharmaceutical manufacturers to pay rebates on Medicaid managed care utilization and by enlarging the population potentially eligible for Medicaid drug benefits. Pricing and rebate programs must also comply with the Medicaid rebate requirements of the U.S. Omnibus Budget Reconciliation Act of 1990. The American Rescue Plan Act of 2021 eliminated the statutory cap on Medicaid Drug Rebate Program rebates that manufactures pay to state Medicaid programs. Elimination of this cap may require pharmaceutical manufacturers to pay more in rebates than it receives on the sale of products, which could have a material impact on our business.

The Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (“MMA”) established the Medicare Part D program to provide a voluntary prescription drug benefit to Medicare beneficiaries. Under Part D, Medicare beneficiaries may enroll in prescription drug plans offered by private entities that provide coverage of outpatient prescription drugs. Unlike Medicare Parts A and B, Part D coverage is not standardized. Part D prescription drug plan sponsors are not required to pay for all covered Part D drugs, and each drug plan can develop its own drug formulary that identifies which drugs it will cover and at what tier or level. However, while all Medicare drug plans must give at least a standard level of coverage set by Medicare, Part D prescription drug plan sponsors are not required to pay for all covered Part D drugs, and each drug plan can develop its own drug formulary that identifies which drugs it will cover and at what tier or level. These Part D prescription drug formularies must include drugs within each therapeutic category and class of covered Part D drugs, though not necessarily all the drugs in each category or class. Any formulary used by a Part D prescription drug plan must be developed and reviewed by a pharmacy and therapeutic committee. Government payment for some of the costs of prescription drugs may increase demand for drugs for which we may obtain marketing approval. However, any negotiated prices for our drugs covered by a Part D prescription drug plan will likely be lower than the prices we might otherwise obtain. Moreover, while the MMA applies only to drug benefits for Medicare beneficiaries, private payors often follow Medicare coverage policy and

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payment limitations in setting their own payment rates. Any reduction in payment that results from the MMA may result in a similar reduction in payments from non-governmental payors.

For a drug product to receive federal reimbursement under the Medicaid or Medicare Part B programs or to be sold directly to U.S. government agencies, the manufacturer must extend discounts to entities eligible to participate in the 340B drug pricing program. The required 340B discount on a given product is calculated based on the AMP and Medicaid rebate amounts reported by the manufacturer. As of 2010, the ACA expanded the types of entities eligible to receive discounted 340B pricing, although, under the current state of the law, with the exception of children’s hospitals, these newly eligible entities will not be eligible to receive discounted 340B pricing on orphan drugs. In addition, as 340B drug pricing is determined based on AMP and Medicaid rebate data, the revisions to the Medicaid rebate formula and AMP definition described above could cause the required 340B discount to increase. In addition, legislation may be introduced that, if passed, would further expand the 340B program to additional covered entities or would require participating manufacturers to agree to provide 340B discounted pricing on drugs used in an inpatient setting.

The American Recovery and Reinvestment Act of 2009 provides funding for the federal government to compare the effectiveness of different treatments for the same illness. The plan for the research was published in 2012 by the HHS, the Agency for Healthcare Research and Quality and the National Institutes for Health, and periodic reports on the status of the research and related expenditures are made to Congress. It is also possible that comparative effectiveness research demonstrating benefits in a competitor’s drug could adversely affect the sales of our ADC drug candidate. If third-party payors do not consider our drugs to be cost-effective compared to other available therapies, they may not cover our drugs as a benefit under their plans or, if they do, the level of payment may not be sufficient to allow us to sell our drugs on a profitable basis.

In recent years, additional laws have resulted in direct or indirect reimbursement reductions for certain Medicare providers. For example, the Budget Control Act of 2011, among other things, created measures for spending reductions by Congress. These changes included aggregate reductions to Medicare payments to providers of up to 2% per fiscal year, which went into effect in April 2013 and will remain in effect through 2032, unless additional congressional action is taken. The American Taxpayer Relief Act of 2012, among other things, reduced Medicare payments to several providers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. These laws, and future state and federal healthcare reform measures, as discussed further below, may be adopted in the future, any of which may result in additional reductions in Medicare and other healthcare funding and otherwise affect the prices we may obtain for any product candidate for which it may obtain regulatory approval or the frequency with which any such product candidate is prescribed or used.

As noted above, the marketability of any products for which we receive regulatory approval for commercial sale may suffer if the government and other third-party payors fail to provide adequate coverage and reimbursement. We expect that an increasing emphasis on cost containment measures in the U.S. will continue to increase the pressure on pharmaceutical pricing. Coverage policies and third-party reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more products for which we receive regulatory approval, less favorable coverage policies and reimbursement rates may be implemented in the future.

In addition, in some foreign countries, the proposed pricing for a drug must be approved before it may be lawfully marketed. The requirements governing drug pricing vary widely from country to country. For example, the European Union provides options for its member states to restrict the range of medicinal drugs for which their national health insurance systems provide reimbursement and to control the prices of medicinal drugs for human use. A member state may approve a specific price for the medicinal drug or it may instead adopt a system of direct or indirect controls on the profitability of the company placing the medicinal drug on the market. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical drugs will allow favorable reimbursement and pricing arrangements for any of our drugs. Historically, drugs launched in the European Union do not follow price structures of the U.S. and generally tend to be significantly lower.

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U.S. Healthcare Reform

The ACA has had a significant impact on the healthcare industry. The ACA expanded coverage for the uninsured while at the same time containing overall healthcare costs. With regard to pharmaceutical products, the ACA, among other things, addressed a new methodology by which rebates owed by manufacturers under the MDRP are calculated for drugs that are inhaled, infused, instilled, implanted, or injected, increased the minimum Medicaid rebates owed by manufacturers under the MDRP and extended the rebate program to individuals enrolled in Medicaid managed care organizations, established annual fees and taxes on manufacturers of certain branded prescription drugs, and a new Medicare Part D coverage gap discount program, in which manufacturers must agree to offer 70% (increased pursuant to the Bipartisan Budget Act of 2018, effective as of 2019) point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D. The American Rescue Plan Act of 2021 eliminated the statutory cap on Medicaid Drug Rebate Program rebates that manufacturers pay to state Medicaid programs. Elimination of this cap may require pharmaceutical manufacturers to pay more in rebates than they receive on the sale of products, which could have a material impact on our business.

The ACA requires pharmaceutical manufacturers of branded prescription drugs to pay a branded prescription drug fee to the federal government. Each such manufacturer is required to pay a prorated share of the branded prescription drug fee based on the dollar value of its branded prescription drug sales to certain federal programs identified in the law. The ACA also expanded the 340B program to include additional types of covered entities. Federal law requires that any company that participates in the Medicaid rebate program also participate in the 340B program in order for federal funds to be available for the manufacturer’s drugs under Medicaid. The 340B program requires participating manufacturers to agree to charge statutorily defined covered entities no more than the 340B “ceiling price” for the manufacturer’s covered outpatient drugs. In addition, in order to be eligible to have its products paid for with federal funds under the Medicaid programs and purchased by certain federal grantees and agencies, a manufacturer also must participate in the Department of Veterans Affairs Federal Supply Schedule (“FSS”) pricing program, established by Section 603 of the Veterans Health Care Act of 1992. Under this program, the manufacturer is obligated to make products available for procurement on an FSS contract and charge a price to four federal agencies—the Department of Veterans Affairs, the Department of Defense, the Public Health Service, and the Coast Guard—that is at least 24% less than the Non-Federal Average Manufacturing Price for the prior fiscal year.

Since the enactment of the ACA, there have been judicial and Congressional challenges to certain aspects of the ACA. In June 2021, the Supreme Court held that Texas and other challengers had no legal standing to challenge the ACA, upholding the ACA. In January 2021, President Biden also issued an executive order to initiate a special enrollment period to allow people to obtain health insurance coverage through the ACA marketplace and instructs certain governmental agencies to review and reconsider their existing policies and rules that limit access to healthcare, among others. We cannot predict how future litigation, healthcare reform measures of the current administration, or what other regulations will ultimately be implemented at the federal or state level, or the effect of any future legislation or regulation may have on our business.

Moreover, there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed and enacted federal and state 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 drug products. At the federal level, for example, in September 2018, CMS announced that it will allow Medicare Advantage Plans the option to use step therapy for Part B drugs beginning January 1, 2019. Additionally, CMS issued a final rule, effective on July 9, 2019, that requires direct-to-consumer television advertisements of prescription drugs and biological products, for which payment is available through or under Medicare or Medicaid, to include in the advertisement the Wholesale Acquisition Cost, or list price, of that drug or biological product if it is equal to or greater than $35 for a monthly supply or usual course of treatment. Prescription drugs and biological products that are in violation of these requirements will be included on a public list.

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In July 2021, the Biden administration released an executive order, “Promoting Competition in the American Economy,” with multiple provisions aimed at increasing competition for prescription drugs. In August 2022, Congress passed the Inflation Reduction Act of 2022, which includes prescription drug provisions that have significant implications for the pharmaceutical industry and Medicare beneficiaries, including allowing the federal government to negotiate a maximum fair price for certain high-priced single source Medicare drugs, imposing penalties and excise tax for manufacturers that fail to comply with the drug price negotiation requirements, requiring inflation rebates for all Medicare Part B and Part D drugs, with limited exceptions, if their drug prices increase faster than inflation, and redesigning Medicare Part D to reduce out-of-pocket prescription drug costs for beneficiaries, among other changes. In June 2024, in Loper Bright Enterprises v. Raimondo, the U.S. Supreme Court overruled the Chevron doctrine, which gave deference to regulatory agencies’ statutory interpretations in litigation against federal government agencies, such as the FDA, where the law is ambiguous. This landmark Supreme Court decision may invite various stakeholders to bring lawsuits against the FDA to challenge longstanding decisions and policies, such as market exclusivities, which could lead to uncertainties in the industry. Further, changes in the leadership of the FDA and other federal agencies under the current administration may lead to new policies, changes in the regulations, or disruptions to the operations of federal agencies, any of which may impact our clinical development plans. There are important exemptions to Maximum Fair Price including medications that are orphan drug designated and approved, for only one rare disease, and drugs with low Medicare spend as defined by CMS. In an effort to curb Medicare patients’ out-of-pocket costs for prescription drugs, the Part D redesign legislation requires manufacturers to contribute to the catastrophic coverage phase for Part D Drugs, as discounts through a manufacturer discount program. Various industry stakeholders have initiated lawsuits against the federal government asserting that the price negotiation provisions of the Inflation Reduction Act are unconstitutional. Further, the current administration has issued executive orders focused on decreasing prescription drug prices, including directing the Secretary of HHS to establish a mechanism through which American patients can buy drugs directly from manufacturers who sell at a most-favored-nation price and directing the U.S. Trade Representative and Secretary of Commerce to take action to ensure foreign countries are not engaged in practices that purposefully and unfairly undercut market prices and drive price hikes in the U.S. In November 2025, CMS announced a voluntary initiative called the GENEROUS Model (GENErating cost Reductions fOr U.S. Medicaid Model) to introduce the option of most-favored-nation pricing to the Medicaid program, whereby a drug manufacturer may voluntarily offer supplemental rebates to participating state Medicaid programs for a manufacturer’s covered outpatient drugs. Government agreements with pharmaceutical companies and other measures that use most-favored-nation pricing targets for prescription drugs or that increase generic and biosimilar drug entry sooner than expected can have a material adverse effect on our industry, ability to set adequate pricing for new drugs to recover R&D costs, ability to attract potential investors and potential buyers in the future, or the pricing of our approved product in the U.S. and in foreign countries. The impact of these judicial challenges as well as future actions and agency rules implemented by the government on us and the pharmaceutical industry as a whole is unclear. Furthermore, any reduction in reimbursement from Medicare and other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability, or commercialize any of the product candidates for which we receive approval. At the state level, legislatures have 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. For example, the FDA has authorized the state of Florida to develop a program to import certain prescription drugs from Canada for a limited period to help reduce drug costs, provided that Florida’s Agency for Health Care Administration meets the requirements set forth by the FDA. Other states may follow Florida.

We expect that additional federal and state healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare drugs and services, and in turn could significantly reduce the projected value of certain development projects and reduce our profitability and may increase our regulatory burdens and operating costs.

Moreover, 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 I 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

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no obligation for a drug manufacturer to make its drug products available to eligible patients as a result of the Right to Try Act, but the manufacturer must develop an internal policy and respond to patient requests according to that policy.

Other Healthcare Laws

For our product and any product candidates that obtain regulatory approval and are marketed in the United States, our arrangements, directly or indirectly, with third-party payors, healthcare providers, and customers 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 market, sell, and distribute any products for which we obtain marketing approval. Our employees, consultants, and commercial partners may engage in misconduct or other improper activities, including non-compliance with regulatory standards and requirements. Federal and state healthcare laws and regulations that may affect our ability to conduct business, include, without limitation:

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FDA, Department of Justice, and other government authority prohibitions against the advertisement, promotion and labeling of our products for off-label uses, or uses outside the specific indications approved by the FDA;

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the federal Anti-Kickback Statute, which broadly prohibits, among other things, any person from knowingly and willfully offering, soliciting, receiving or providing remuneration, directly or indirectly, in exchange for or to induce either the referral of an individual for, or the purchase, order or recommendation of, any good or service for which payment may be made under federal healthcare programs, such as Medicare or Medicaid. A person or entity does not need to have actual knowledge of the statute or specific intent to violate it to have committed a violation;

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the federal False Claims Act, which prohibits, among other things, individuals or entities from knowingly presenting, or causing to be presented, false claims, or knowingly using false statements, to obtain payment from the federal government. These laws have been interpreted to apply to arrangements between manufacturers, on the one hand, and prescribers, purchasers, and other healthcare-related professionals on the other. They can apply to manufacturers who provide inaccurate information on coverage, coding, and reimbursement of their products to persons who bill third-party payers. In addition, manufacturers have been prosecuted or faced civil and criminal liability under these laws for a variety of alleged promotional and marketing activities, including violations of the federal Anti-Kickback Statute and engaging in off-label promotion that caused claims to be submitted for non-covered off-label uses. Private individuals can bring False Claims Act “qui tam” actions, on behalf of the government and such individuals, commonly known as “whistleblowers,” may share in amounts paid by the entity to the government in fines or settlement;

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the Health Insurance Portability and Accountability Act of 1996 (“HIPAA”), as amended, which among other things, also created criminal liability for knowingly and willfully falsifying or concealing a material fact or making a materially false statement in connection with the delivery of or payment for healthcare benefits, items or services. Similar to the U.S. federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation;

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Federal criminal laws that prohibit executing a scheme to defraud any healthcare benefit program or making, or causing to be made, false statements relating to healthcare matters;

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the federal Civil Monetary Penalties Law, which prohibits, among other things, offering or transferring remuneration to a federal healthcare beneficiary that a person knows or should know is likely to influence the beneficiary’s decision to order or receive items or services reimbursable by the government from a particular provider or supplier;

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the Foreign Corrupt Practices Act, the U.K. Bribery Act of 2010, and other local anti-corruption laws that apply to our international activities;

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the federal Physician Payment Sunshine Act (“Open Payments”), and implementing regulations, which require applicable group purchasing organizations and manufacturers of covered drugs, medical devices, biologicals and medical supplies for which payment is available under Medicare, Medicaid, or the Children’s Health Insurance Program to report annually to the CMS information related to certain payments and other transfers of value made to covered recipients, including licensed physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain non-physician healthcare professionals (such as physician assistants and nurse

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practitioners, among others), and teaching hospitals, and information regarding ownership and investment interests held by physicians and their immediate family members;

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analogous state and foreign law equivalents of each of the above federal laws, such as anti-kickback and false claims laws which may apply to items or services reimbursed by any third-party payor, including commercial insurers or patients; state laws that require pharmaceutical manufacturers to comply with the industry’s voluntary compliance guidelines and the applicable compliance guidance promulgated by the federal government or otherwise restrict payments that may be made to healthcare providers and other potential referral sources; state laws that require manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers or marketing expenditures; consumer protection and unfair competition laws, which broadly regulate marketplace activities and activities that potentially harm customers; foreign and state laws, including the EU General Data Protection Regulation (“GDPR”) and a version of the GDPR adopted in the United Kingdom (“UK GDPR”), and state laws and regulations, including general legislation such as the California Consumer Protection Act (“CCPA”), and sector- or subject matter-specific laws and regulations, governing the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts; and state laws related to insurance fraud in the case of claims involving private insurers.

The scope and enforcement of each of these laws are uncertain and subject to rapid change in the current environment of healthcare reform. 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 may not comply with current or future statutes, regulations, or case law involving applicable fraud and abuse or other healthcare laws and regulations, and we could also be subject to claims, demands, and litigation initiated by private individuals or entities related to these matters. If our operations, including those of our contractors or agents who conduct business for or on our behalf, are alleged or 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 of drugs from government funded healthcare programs, such as Medicare and Medicaid, reputational harm, additional oversight, and reporting obligations if we becomes 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 alleged or found to be not in compliance with applicable laws, they may be subject to similar actions, penalties, and sanctions, which may also adversely affect our business. 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 the business.

Privacy and Data Protection Laws

We are subject to laws and regulations covering data privacy and the protection of health-related and other personal information. Federal, state, and foreign laws also govern the privacy and security of health information in some circumstances. For example, HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, and their implementing regulations also impose obligations on covered entities such as health insurance plans, healthcare clearinghouses, and certain health care providers and their respective business associates and their covered subcontractors, including mandatory contractual terms, with respect to safeguarding the privacy, security and transmission of individually identifiable health information, State data privacy and security laws may differ from each other in significant ways and often are not pre-empted by HIPAA, which may complicate compliance efforts in states or jurisdictions we conduct business. For example, in 2020, California enacted the CCPA, which created new individual privacy rights for California consumers, as defined in the law, and placed increased privacy and security obligations on entities handling personal data of consumers or households. The CCPA requires covered companies to provide certain disclosures to consumers about its data collection, use and sharing practices, and to provide affected California residents with ways to opt-out of certain sales or transfers of personal information. The CCPA went into effect on January 1, 2020 and became enforceable by the California Attorney General on July 1, 2020. It was further amended and supplemented by the California Privacy Rights Act, which became effective on January 1, 2023, and imposes additional privacy and security obligations on companies doing business in California. While

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there is currently an exception in the CCPA for protected health information that is subject to HIPAA and clinical trial regulations, as currently written, numerous other states have enacted legislation similar to the CCPA, and several states have enacted other privacy and security legislation, such as Washington’s My Health, My Data Act, which includes a private right of action. The CCPA and such other new and evolving legislation may impact our business activities significantly, and these and other applicable state and foreign privacy laws, as well as uncertain changes in future regulation and legislation, could impact our business strategies, increase our potential liability, increase our compliance costs, and adversely affect our business.

The collection and use of personal health data in the European Union are governed by the GDPR and applicable member state legislation. The GDPR and related member state legislation impose several requirements relating to consent of the individuals to whom the personal data relates, information provided to the individuals, and the security and confidentiality of personal data. Legislation similar to the GDPR, the UK GDPR, also has been adopted in the United Kingdom. The GDPR and UK GDPR also impose strict rules on the transfer of personal data out of the European Union and United Kingdom, respectively, to the U.S. Both the GDPR and UK GDPR provide for substantial fines for noncompliance. Failure to comply with the requirements of the GDPR, UK GDPR, or data protection laws of European Union member states may result in fines and other administrative penalties. The GDPR and UK GDPR may impose additional responsibility and liability in relation to personal data that we process and we may be required to put in place additional mechanisms in an effort to achieve and maintain compliance with their obligations. This may be onerous and adversely affect our business, financial condition, results of operations, and prospects.

Foreign Regulatory Matters

European Drug Development

In Europe, any future drug products for which we receive marketing authorization will also be subject to extensive regulatory requirements. As in the United States, medicinal products can only be marketed if a marketing authorization from the competent regulatory agencies has been obtained. Similar to the United States, the various phases of preclinical and clinical research in Europe are subject to significant regulatory controls. Although the European Union Clinical Trials Directive 2001/20/EC (“Clinical Trials Directive”) has sought to harmonize the EU clinical trials regulatory framework, setting out common rules for the control and authorization of clinical trials in the EU, the EU member states have transposed and applied the provisions of the Clinical Trials Directive differently. This has led to significant variations in the member state regimes. Under the current regime, before a clinical trial can be initiated, it must be approved in each of the EU member states where the trial is to be conducted by two distinct bodies: the National Competent Authority (“NCA”) and one or more Ethics Committees (“ECs”). Under the current regime, all suspected unexpected serious adverse reactions to the investigated drug that occur during the clinical trial have to be reported to the NCA and ECs of the member state where they occurred.

In 2014, a new Clinical Trials Regulation 536/2014 (“Clinical Trials Regulation”), replacing the current Directive, was adopted. The Clinical Trials Regulation will become directly applicable in all EU member states (without national implementation) once the EU Portal and Database are fully functional. The implementation of the Clinical Trials Regulation depends on confirmation of full functionality of the Clinical Trials Information System through an independent audit, which commenced in September 2020. This system went into application in first quarter of 2022. From January 31, 2025, any trials approved under the Clinical Trials Directive that continue running will need to comply with the Clinical Trials Regulation, and their sponsors must enter information on the trials in the Clinical Trials Information System. The Clinical Trials Regulation seeks to simplify and streamline the approval of clinical trials in the European Union. For example, the sponsor can submit a single application for approval of a clinical trial via the EU Portal. As part of the application process, the sponsor will propose a reporting member state, which will coordinate the validation and evaluation of the application. The reporting member state shall consult and coordinate with the other member states in which the clinical trial will take place, also referred to as the Member States Concerned. If an application is rejected, it can be amended and resubmitted through the EU Portal. If an approval is issued, the sponsor can start the clinical trial in all Member States Concerned. However, a Member State Concerned can in limited circumstances declare an “opt-out” from an approval. In such a case, the clinical trial cannot be conducted in that member state. The Clinical Trials Regulation also aims to streamline and simplify the rules on safety

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reporting and introduces enhanced transparency requirements such as mandatory submission of a summary of the clinical trial results to the EU Database.

European Drug Review and Approval

In the European Economic Area (“EEA”), which is comprised of the 27 EU member states plus Norway, Iceland, and Liechtenstein, medicinal products can only be commercialized after obtaining approval of an EU marketing authorization application (“MAA”). There are two types of marketing authorizations. The first is the community or centralized EU MAA, which is issued by the European Commission through the Centralized Procedure, based on the opinion of the Committee for Medicinal Products for Human Use (“CHMP”) of the European Medicines Agency and which is valid throughout the entire territory of the EEA. The Centralized Procedure is mandatory for certain types of drugs, such as biotechnology medicinal drugs, orphan medicinal drugs, and medicinal drugs containing a new active substance indicated for the treatment of AIDS, cancer, neurodegenerative disorders, diabetes, auto-immune, and viral diseases. The Centralized Procedure is optional for drugs containing a new active substance not yet authorized in the EEA, or for drugs that constitute a significant therapeutic, scientific, or technical innovation or which are in the interest of public health in the EU.

National EU MAAs, which are issued by the competent authorities of the member states of the EEA and only cover their respective territory, are available for drugs not falling within the mandatory scope of the Centralized Procedure. Where a drug has already been authorized for marketing in a member state of the EEA, this National EU MAA can be recognized in another member states through the Mutual Recognition Procedure. If the drug has not received a National EU MAA in any member state at the time of application, it can be approved simultaneously in various member states through the Decentralized Procedure. Under the Decentralized Procedure an identical dossier is submitted to the competent authorities of each of the member states in which the EU MAA is sought, one of which is selected by the applicant as the Reference Member State (“RMS”). The competent authority of the RMS prepares a draft assessment report, a draft summary of the drug characteristics (“SPC”), and a draft of the labeling and package leaflet, which are sent to the other member states, or the Member States Concerned, for their approval. If the Member States Concerned raise no objections, based on a potential serious risk to public health, to the assessment, SPC, labeling, or packaging proposed by the RMS, the drug is subsequently granted a national EU MAA in all the member states, i.e., in the RMS and the Member States Concerned.

Under the above-described procedures, before granting the EU MAA, the EMA or the competent authorities of the member states of the EEA make an assessment of the risk-benefit balance of the drug on the basis of scientific criteria concerning its quality, safety, and efficacy.

European Chemical Entity Exclusivity

In Europe, new chemical entities, sometimes referred to as new active substances, qualify for eight years of data exclusivity upon marketing authorization and an additional two years of market exclusivity. This data exclusivity, if granted, prevents regulatory authorities in the EU from referencing the innovator’s data to assess a generic application for eight years, after which generic marketing authorization can be submitted, and the innovator’s data may be referenced, but not approved for two years. The overall ten-year period will be extended to a maximum of 11 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.

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 EU, commonly referred to as Brexit. Thereafter, on March 29, 2017, the country formally notified the EU of its intention to withdraw pursuant to Article 50 of the Lisbon Treaty. The United Kingdom formally left the EU on January 31, 2020. A transition period began on February 1, 2020, during which EU pharmaceutical law remains applicable to the United Kingdom and ended on December 31, 2020. Although the United Kingdom is no longer a member of the EU, EU law remains applicable in Northern Ireland, as set forth in the Protocol on Ireland and Northern Ireland and as amended by the Windsor Framework, which will be implemented in Northern Ireland on January 1, 2025. There are a number of new marketing authorization routes available in the United Kingdom, Great Britain (England, Scotland and Wales) or Northern Ireland, in addition to the national procedure. As with the EU position, a company can only start to market a medicine in the United Kingdom once it has received a marketing

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authorization. The main legislation that applies to clinical trials in the United Kingdom is the United Kingdom Medicines for Human Use (Clinical Trials) Regulations 2004, which transposes the Clinical Trials Directive into domestic law. Consequently, the requirements and obligations that relate to the conduct of clinical trials in the UK currently remain largely aligned with the EU position. It is unclear how future regulatory regime in the United Kingdom will impact regulations of products, manufacturers, and approval of product candidates in the United Kingdom.

Other Foreign Countries

For other countries outside of the United States and the European Union, the requirements governing the conduct of clinical trials, drug approval or marketing authorization, pricing, and reimbursement vary from country to country. In all cases, clinical trials must be conducted in accordance with GCP requirements and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki, which is a statement of ethical principles for medical research involving human subjects, including research on identifiable human material and data, developed by the World Medical Association.

If we fail to comply with applicable foreign regulatory requirements, we may be subject to, among other things, fines, suspension or withdrawal of regulatory approvals, product recalls, seizure of products, operating restrictions, and criminal prosecution.

Employees and Human Capital

We have operated by leveraging skilled experts, consultants, contract research organizations, and contractors to manage our clinical operations, manufacturing, research and development, and other functions under the leadership and direction of our management. We will continue to expand our infrastructure to manage our operations, including commercial with additional full-time employees.

As of December 31, 2025, we had 23 full-time or part-time employees. None of our employees are represented by labor unions or covered by collective bargaining agreements. We consider the relationship with our employees to be good.

Our human capital resources objectives include, as applicable, identifying, recruiting, retaining, incentivizing and integrating our existing and additional employees, advisors and consultants, while being committed to a diverse and dynamic workplace. The principal purposes of our equity incentive plans are to attract, retain and reward personnel through the granting of equity-based compensation awards in order to increase shareholder value and the success of our company by motivating such individuals to perform to the best of their abilities and achieve our objectives.

Our Corporate Information

We were originally incorporated in the State of Delaware in November 2007 under the name “Zeta Acquisition Corp. II.” Zeta Acquisition Corp. II was a “shell” company registered under the Exchange Act with no specific business plan or purpose until it began operating the business of Aerpio Pharmaceuticals, Inc. through a merger in March 2017. In August 2021, we effected a reverse merger pursuant to which a wholly owned subsidiary of ours, merged with and into Aadi Subsidiary, Inc. (formerly known as Aadi Bioscience, Inc. or "Private Aadi") (“Aadi Subsidiary”), with Aadi Subsidiary surviving as a wholly owned subsidiary of ours (the "Merger"). Upon the closing of the Merger, we changed our name from “Aerpio Pharmaceuticals, Inc.” to “Aadi Bioscience, Inc.” and the name of Private Aadi was changed from “Aadi Bioscience, Inc.” to “Aadi Subsidiary, Inc.”

In connection with the FYARRO Divestiture, KAKEN acquired 100% of the outstanding shares of capital stock of Aadi Subsidiary. On March 18, 2025, in connection with such transaction, we changed our name from "Aadi Bioscience, Inc." to "Whitehawk Therapeutics, Inc."

Since March 2025, our principal executive offices have been located at 2 Headquarters Plaza, East Building, 11th Floor, Morristown, NJ 07960. Prior to March 2025, our principal executive offices were located at 17383 Sunset Boulevard, Suite A250, Pacific Palisades, California 90272. We maintain a website at www.whitehawktx.com, to which we regularly post copies of our press releases as well as additional information about us. Our filings with the Securities and Exchange Commission (the “SEC”) will be available free of charge through the website as soon as reasonably practicable after being electronically filed with or furnished to the SEC. Information contained in our website does not constitute a part of this Annual Report on Form 10-K or any of our other filings with the SEC unless specifically incorporated herein by reference.

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In addition, our filings with the SEC may be accessed through the SEC’s Electronic Data Gathering, Analysis, and Retrieval system at http://www.sec.gov. All statements made in any of our securities filings, including all forward-looking statements or information, are made as of the date of the document in which the statement is included, and we do not assume or undertake any obligation to update any of those statements or documents unless we are required to do so by law.

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