Company: WHWK
Filing Date: 2025-01-31
Form Type: DEFM14A
Source: 0001193125-25-018470
Chunk: 184

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-01-31
Form: DEFM14A
Chunk 184
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 surface permitting internalization of the TOPO1 inhibitor payload. This allows mMUC16-CPT113 to bypass the antigen sink of circulating CA125, and directly target the tumor surface.

Preclinical data shows that mMUC16-CPT113 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

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next wave approach has the potential for improved response rates in ovarian cancer and other gynecological cancers. For example, our product candidate mMUC16-CPT113, 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 plan to complete IND-enabling studies and linker-payload process development in 2025 with IND submission by the end
of 2025. Subject to FDA acceptance, we plan to initiate Phase 1 trial in ovarian cancer in 2026, with the potential to expand into other cancers affecting women, such as endometrial and cervical cancer, where we believe mMUC16-CPT113 can make a
meaningful impact.

biSEZ6-CPT113

Overview

Our product candidate biSEZ6-CPT113 is a biparatopic ADC targeting to two or more antigens of the SEZ6 protein. There is limited class competition as ABBV-706 is the only clinical-stage SEZ6 ADC currently in development. Our product candidate is the only biparatopic ADC in development for SCLC and high-grade neuroendocrine tumors (“NET”) patients and we
believe this approach of binding to two independent sites on the target antigen protein will achieve superior outcomes compared to other SCLC ADCs. In vitroandin vivoassays demonstrate increased binding and internalization compared
to the monotopic ABBV-706. We plan to complete IND-enabling studies and linker-payload process development in 2025 and first half of 2026, with an IND submission planned
in mid-2026.

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| Target Overview: SE