Day One Biopharmaceuticals, Inc., a clinical-stage biopharmaceutical company, develops and commercializes targeted therapies for patients with genetically defined cancers. Its lead product candidate is DAY101, an oral brain-penetrant type II pan-rapidly accelerated fibrosarcoma kinase inhibitor that is in Phase II clinical trial for pediatric patients with relapsed/progressive low-grade glioma. The company is also developing Pimasertib, an oral small molecule inhibitor of mitogen-activated protein kinase kinases 1 and 2. Day One Biopharmaceuticals, Inc. was incorporated in 2018 and is headquartered in South San Francisco, California.