Company: WHWK
Filing Date: 2025-04-25
Form Type: 424B5
Source: 0001193125-25-097064
Chunk: 23

Company: Whitehawk Therapeutics, Inc.
Filing Date: 2025-04-25
Form: 424B5
Chunk 23
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). As part of our continued evaluation of potential new clinical programs for FYARRO, either as a single agent or in combination with other targeted therapies, we selected these new clinical indications based on preclinical data supporting these programs, which we believe are promising, and the prospect of providing enhanced therapeutic benefit in these indications with meaningful patient populations and high unmet needs. We are currently enrolling patients in a Phase 2 open-label, multi-institutional study to evaluate the efficacy and safety of the combination of FYARRO with letrozole for the treatment of advanced or recurrent endometrioid-type endometrial cancer (EEC) and a Phase 2 multicenter, open-label, single-armtrial to evaluate FYARRO in adult patients with functional or non-functional,well-differentiated, locally advanced unresectable or metastatic NETs of the GI tract, lung, or pancreas who have received no more than two prior lines of therapy. In October 2022, we entered into a collaboration and supply agreement with Mirati Therapeutics, Inc. (“Mirati”) to evaluate the combination of Mirati’s adagrasib, a KRASG12C selective inhibitor, and FYARRO in KRASG12C mutant non-smallcell lung cancer (NSCLC) and other solid tumors. Under the terms of the agreement, Mirati will be responsible for sponsoring and operating the Phase 1/2 study and we will supply study drug and jointly share the cost of the study. The primary objective of this multi-center, single-arm,open-label Phase 1/2 trial is to determine the optimal dose and recommended Phase 2 dose for the combination of adagrasib and FYARRO in patients with KRASG12C-mutant solid tumors. In addition, the study will investigate the safety, tolerability and efficacy of adagrasib and FYARRO in combination in patients both with and without prior

2

exposure to a KRASG12C inhibitor. The trial will build on preclinical data showing enhanced anti-tumor efficacy with the combination of adagrasib and FYARRO relative to either agent alone. In
August 2023, we announced that the first patient dosing occurred in the Phase 1/2 trial.

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