Company: WHWK
Filing Date: 2025-01-21
Form Type: PREM14A
Source: 0001193125-25-009599
Chunk: 190

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-01-21
Form: PREM14A
Chunk 190
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 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: 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.   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.

| 1. | Aadi analysis based on Human Protein Atlas, Gepia, and literature review. |

Emerging Therapies and their Limitations Currently, ABBV-706(developed by AbbVie) is the only clinical stage SEZ6 ADC in development. ABBV-706is