Day One Biopharmaceuticals Holding Company LLC

• Day One Biopharmaceuticals Holding Company LLC
• Health-Care

DAWN

Day One was founded to address a critical unmet need: children with cancer are being left behind in a cancer drug development revolution. Our name was inspired by the “The Day One Talk” that physicians have with patients and their families about an initial cancer diagnosis and treatment plan. We aim to re-envision cancer drug development and redefine what’s possible for all people living with cancer–regardless of age–starting from Day One.

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, a vulnerable population that has been underserved in the recent revolution in targeted therapeutics and immuno-oncology. 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 been studied in over 250 patients and has been shown to be well-tolerated as a monotherapy. 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/mitrogen-activated protein kinase, or MAPK, pathway leading to uncontrolled cell growth.

We have initiated a pivotal Phase 2 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. We expect to dose the first patient in this trial in the second quarter of 2021, to report initial data from this trial in the first half of 2022, and to file a related New Drug Application, or NDA with the U.S. Food and Drug Administration, or FDA, in 2023. 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.

Our second product candidate, pimasertib, is an oral, highly-selective small molecule inhibitor of mitogen-activated protein kinase kinases 1 and 2 (MEK), a well-characterized key signaling node in the MAPK pathway. We expect to initiate a Phase 1b/2 trial in the first quarter of 2022 to study the combination of DAY101 and pimasertib in patients 12 years and older with various MAPK-altered solid tumors. We believe our business development capabilities combined with our extensive experience in oncology drug development and deep ties within the research and patient advocacy communities, particularly within the pediatric setting, positions us to be a leader in identifying, acquiring and developing therapies for patients of all ages. We hold exclusive worldwide rights to DAY101 for all oncology indications and to pimasertib for all therapeutic areas subject to certain milestone and royalty payments. For additional information, see the subsection titled “—Material agreements.” 

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