Day One Biopharmaceuticals
Brisbane, California, United States · Biopharma, Biotechnology, Health Care
Day One Biopharmaceuticals is a clinical-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases. The company believes in putting kids first and is developing targeted therapies that deliver to their needs. Day One was founded to address the dire lack of therapeutic development in pediatric cancer and aims
Key facts
- Headquarters
- Brisbane, California, United States
- Employees
- 51
- Industries
- Biopharma, Biotechnology, Health Care
- Website
- dayonebio.com
- Company page
Recent activity at Day One Biopharmaceuticals
- : SEC 8-K (5.02):
- : SEC 8-K (1.01): On March 6, 2026, Servier Pharmaceuticals LLC, along with its subsidiary Servier Detroit Inc. and Day One Biopharmaceuticals, entered into a Merger Agreement wherein Servier Detroit will initiate a cash tender offer to acquire all outstanding shares of Day One Biopharmaceuticals at a price of $21.50 per share. The consummation of the offer is contingent upon conditions including majority shareholder consent and regulatory approvals under the Hart-Scott-Rodino Act. The offer is set to commence within 15 business days of the agreement and is not subject to financing conditions, indicating strategic confidence in the merger's viability. The merger aims for Servier to integrate Day One as a wholly owned subsidiary, enhancing its operational portfolio in the biopharmaceutical space.
- : SEC 8-K (7.01): On March 2, 2026, Day One Biopharmaceuticals, Inc. disclosed a positive opinion received by Ipsen Pharma SAS from the Committee for Medicinal Products for Human Use regarding the conditional marketing authorization of OJEMDA TM (tovorafenib). This drug is intended for treating children with relapsed or refractory BRAF-altered pediatric low-grade glioma. This update reflects the ongoing collaboration as previously announced in July 2024, where Day One Biopharmaceuticals entered an exclusive license agreement with Ipsen for commercialization outside of the U.S. The implications of this development enhance the strategic positioning of the Company in pediatric oncology markets. The enhanced corporate presentation is included as Exhibit 99.1.
- : SEC 8-K (7.01): On February 24, 2026, Day One Biopharmaceuticals, Inc. updated its corporate presentation, which is attached as Exhibit 99.3 to the filing. This Regulation FD disclosure provides shareholders with the latest strategic corporate information, relevant financial metrics, and forward-looking insights pertaining to the company. The filing also references a press release detailing the company's financial results for the quarter and year ended December 31, 2025, indicating ongoing transparency and communication with investors. The updates in the presentation are significant for understanding the company’s current position and future direction.
- : SEC 8-K (7.01): On January 11, 2026, the Company announced its 2026 priorities and milestones, including the expectation to complete enrollment in the pivotal Phase 3 FIREFLY-2 clinical trial evaluating tovorafenib as a front-line therapy for patients aged up to 25 years with relapsed or refractory pediatric low-grade glioma in the first half of 2026. Additionally, the Company plans to provide initial data from the Phase 1a clinical trial for DAY301 in the second half of 2026 and advance the Emi-Le program with Phase 1 clinical data by mid-2026. The announcement included details on future participation in the 44th Annual J.P. Morgan Healthcare Conference on January 12, 2026. This filing emphasizes the Company's ongoing commitment to its clinical development pipeline and strategic planning for 2026.
- : SEC 8-K (1.01): On January 6, 2026, the Parent and the Rights Agent entered into a Contingent Value Rights (CVR) Agreement as part of a merger agreement. This agreement governs the terms for cash payments to holders of CVRs contingent upon the achievement of specific milestones related to the drug emiltatug ledadotin (commonly referred to as Emi-Le). Key milestones include payments of up to $22.25 per CVR, contingent on FDA breakthroughs, development milestones with Janssen Biotech Inc., and sales achievements by certain deadlines ranging from 2026 to 2037. The agreement restricts the transferability of CVRs, ensuring that holders must comply with specific terms outlined in the agreement. Strategic implications include potential revenue from milestone payments, incentivizing the development and commercialization of Emi-Le, reflecting the strategic focus on rare cancer treatment.
- : Day One to acquire Mersana for $130 million
- : SEC 8-K (8.01): On November 24, 2025, the Company announced updated clinical data from the FIREFLY-1 trial, specifically regarding the treatment with tovorafenib. The data presented involves 76 patients, with a reported overall response rate of 53% and a median duration of response of 19.4 months. Notably, 44 patients (58%) completed 26 or more cycles of treatment, equating to approximately 24 months. The trial's findings suggest a promising treatment-free observation period, with a median time-to-next-treatment of 42.6 months and minimal tumor rebound, as 31% of patients experienced a significant increase in tumor size post-therapy. Importantly, no new safety signals were identified in this three-year analysis, indicating sustained efficacy and safety of tovorafenib in the studied population.
- : SEC 8-K (1.01): On November 12, 2025, Day One Biopharmaceuticals, Inc. and its subsidiary, Emerald Merger Sub, Inc., entered into a Material Definitive Agreement with Mersana Therapeutics, Inc. The agreement outlines a tender offer to acquire all outstanding shares of Mersana's common stock at $25.00 per share, along with one contingent value right representing milestone payments of up to $30.25 per share. The tender offer is set to remain open for 20 business days, and following its completion, Merger Sub will merge with Mersana, making Mersana a wholly owned subsidiary of Day One Biopharmaceuticals. The merger is expected to close by the end of January 2026, pending customary closing conditions.
- : SEC 8-K (1.01): On November 12, 2025, Day One Biopharmaceuticals, Inc. entered into an Agreement and Plan of Merger with Emerald Merger Sub, Inc. and Mersana Therapeutics, Inc. Under the terms of the agreement, Emerald Merger Sub will commence a tender offer to acquire all outstanding shares of Mersana Therapeutics common stock at a price of $25.00 per share, payable in cash. This merger is significant as it marks Day One's strategic expansion into the biopharmaceutical sector through this acquisition. The cash transaction reflects a robust valuation of the Target Shares during a crucial time for both companies.
Day One Biopharmaceuticals funding history
| Date | Round | Amount |
|---|---|---|
| Feb 2021 | Series B | $130.0M |
Leadership
- Lindsey Summers, Associate Director, Talent
- Lindsey Summers, Associate Director, Talent
- Ryan Sanders, Vice President, Talent
- Ryan Sanders, Vice President, Talent
Verified email and direct lines for Day One Biopharmaceuticals’s decision-makers are on Fundz. See plans — or book a 15-minute walkthrough.
Employee benefit plans
Day One Biopharmaceuticals files 11 employee benefit plans with the U.S. Department of Labor, including a retirement plan. The next plan year renews in Dec 2026.
Day One Biopharmaceuticals in the news
- Servier and Day One Biopharmaceuticals announce acquisition to expand Servier’s rare oncology portfolio - GlobeNewswire (Mar 06, 2026)
- Servier to acquire Day One, maker of pediatric cancer drug, for $2.5B - STAT (Mar 06, 2026)
- Servier Adds to Childhood Brain Tumor Portfolio With $2.5B Day One Buy - BioSpace (Mar 06, 2026)
- France: Servier acquires Day One Bio for US$2.5bn - Investors in Healthcare (Apr 27, 2026)
- Servier completes the acquisition of Day One Biopharmaceuticals - PR Newswire (Apr 23, 2026)
- Biotech Stock Catapults 200% On Surprise Takeover - Investor's Business Daily (Nov 13, 2025)
- Day One Reports Fourth Quarter and Full Year 2025 Financial - GlobeNewswire (Feb 24, 2026)
- Day One Completes Acquisition of Mersana Therapeutics - GlobeNewswire (Jan 06, 2026)
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About Day One Biopharmaceuticals: questions and answers
What does Day One Biopharmaceuticals do?
Day One Biopharmaceuticals is a clinical-stage biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases. The company believes in putting kids first and is developing targeted therapies that deliver to their needs. Day One was founded to address the dire lack of therapeutic development in pediatric cancer and aims
Where is Day One Biopharmaceuticals headquartered?
Day One Biopharmaceuticals is headquartered in Brisbane, California, United States.
How many employees does Day One Biopharmaceuticals have?
Day One Biopharmaceuticals has about 51 employees.
Has Day One Biopharmaceuticals raised funding?
Yes. Fundz has recorded 1 funding event for Day One Biopharmaceuticals. The most recent, Series B of $130.0M, was in Feb 2021.
Who leads Day One Biopharmaceuticals?
Ryan Sanders is a Vice President, Talent at Day One Biopharmaceuticals.
What is the latest news on Day One Biopharmaceuticals?
On Apr 23, 2026, SEC 8-K (5.02):
Source: Fundz records from SEC filings, press releases and company announcements. How Fundz measures data accuracy