Day One Biopharmaceuticals ^{Priced, Nasdaq: DAWN}

We are a clinical-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for patients of all ages with genetically defined cancers. Initially, we focus our clinical development efforts on pediatric patients living with cancer. Our lead product candidate, DAY101, is an oral, brain-penetrant, highly-selective type II pan-rapidly accelerated fibrosarcoma, or pan-RAF, kinase inhibitor. DAY101 has demonstrated encouraging anti-tumor activity in pediatric and adult populations with specific genetic alterations that result in the over-activation of the RAS/mitogen-activated protein kinase, or MAPK, pathway leading to uncontrolled cell growth. We have initiated a pivotal Phase 2 (FIREFLY-1) trial of DAY101 for pediatric patients with relapsed or progressive low-grade glioma, or pLGG, the most common brain tumor diagnosed in children, for which there are no approved therapies and no standard of care. DAY101 has been granted Breakthrough Therapy designation by the FDA for the treatment of pLGG, based on initial results from a Phase 1 trial which showed evidence of rapid anti-tumor activity, a greater than 50% monotherapy response rate and durable responses in pLGG patients. We also plan to study DAY101 alone or in combination with additional agents that target other key signaling nodes in the MAPK pathway in patient populations where various genetic alterations are believed to play an important role in driving disease.