Company: DAWN
Filing Date: 2025-02-25
Form Type: 10-K
Source: 0000950170-25-026654
Chunk: 81

Company: Day One Biopharmaceuticals, Inc.
Filing Date: 2025-02-25
Form: 10-K
Item: Item 1
Chunk 81
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 would be administered nivolumab and tovorafenib in combination with nivolumab to assess the tolerability and efficacy of combination therapy with PD-1 (nivolumab) and pan-RAF-kinase (tovorafenib) inhibition for the treatment of children and young adults with craniopharyngioma, however, the study was amended in January 2025 as a single-arm study of tovorafenib only with an estimated enrollment of 57 patients.

A Phase 1/2 study of tovorafenib in combination with vinblastine was initiated in 2024 by the Hospital for Sick Kids in Toronto, Canada, in collaboration with the C17 Council, in patients with relapsed/refractory pediatric low-grade glioma. The study is anticipated to enroll approximately 55 patients.

DAY301

Our second product candidate, DAY301, is a PTK7-targeted ADC composed of a novel humanized anti-PTK7 immunoglobulin G1 monoclonal antibody, or mAb, (referred to as DAY301 mAb) conjugated with a topoisomerase I inhibitor (exatecan mesylate [exatecan]) via a highly stable and hydrophilic modified valine-alanine (VA) cleavable linker. DAY301 is intended for the treatment of patients with advanced solid tumors.

DAY301 targets PTK7, a highly-conserved, catalytically inactive transmembrane protein that is overexpressed in multiple adult cancers. DAY301 demonstrated encouraging preclinical antitumor efficacy in relevant tumor models representing a wide range of solid tumors, including ovarian cancer, NSCLC, TNBC, SCLC, ESCC, CSCC, colorectal cancer, and esophageal adenocarcinoma. DAY301 was tolerated in non-human primate nonclinical toxicology studies with favorable pharmacokinetic and safety profiles. Collectively, the data suggest that DAY301 could potentially have a wide therapeutic window in clinical testing and therefore provide benefits for cancer patients with high unmet medical needs.

Clinical development plan 

We have initiated a Phase 1a/b dose-escalation and cohort expansion study to evaluate the safety and tolerability of DAY301 in patients with tumor types known to have high PTK7 expression. The objective of the Phase 1a study is to identify two recommended dose levels for further evaluation based on safety and anti-tumor activity. Once the two recommended doses are established, a minimum of two cohorts of