Company: WHWK
Filing Date: 2025-01-21
Form Type: PREM14A
Source: 0001193125-25-009599
Chunk: 185

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-01-21
Form: PREM14A
Chunk 185
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C and 23% compared to 21% in patients with TNBC compared to patients with PTK7 mod-highTNBC. 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’scommercial potential was limited by the reduced dose intensity and narrow therapeutic window driven by toxicities consistent with MMAE-associated class effects, including - 122 -

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 Aadi 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:

| • |     | PRO1107, being developed by Genmab following its acquisition of ProfoundBio, is currently in Phase 1/2 with the                                                                                                   
 first patient dosed in February 2024. PRO1107 uses an MMAE payload, which is a tubulin inhibitor similar to the payload in Cofe-P, connected through a protease-cleavable hydrophilic linker system called LD343, 
 and has a DAR of 8.                                                                                                                                                                                               |

| • |     | DAY301 (MTX-13), being developed by Day One Biopharmaceuticals after                                                                                                                                              
 acquiring development and commercialization rights outside of the Greater China area from MabCare Therapeutics, recently initiated a Phase 1 trial. Unlike Cofe-P and PRO1107, DAY301 has a pure exatecan payload 
 which may be associated with myelosuppression. LY4175408, being developed by Eli Lilly, also has a pure exatecan payload. We expect Eli Lilly will submit its IND in 2025.                                        |

| • |