Day One Biopharmaceuticals, Inc. (DAWN)

Day One Biopharmaceuticals was founded in 2018 as a company focused on developing targeted therapies for people with genetically defined cancers, with an emphasis on children and young adults. It was established in the San Francisco Bay Area and later listed its headquarters in Brisbane, California. The company took a pipeline-in-a-product approach, in-licensing oncology assets that large developers had not prioritized and advancing them through focused clinical programs.

Its lead asset was tovorafenib, originally designated DAY101, an oral, brain-penetrant type II pan-RAF kinase inhibitor licensed from Takeda. The drug was developed for pediatric low-grade glioma, the most common type of brain tumor in children, particularly tumors driven by BRAF alterations. Day One also held rights to pimasertib, a MEK1/2 inhibitor, which it explored in combination with other agents in genetically defined tumors.

Day One completed its initial public offering on the Nasdaq Global Select Market in May 2021 under the ticker DAWN. In April 2024 the U.S. Food and Drug Administration granted accelerated approval to tovorafenib, marketed as Ojemda, for relapsed or refractory pediatric low-grade glioma with a BRAF fusion or rearrangement. This made Day One a commercial-stage company, and it entered into a licensing arrangement with Ipsen for development and commercialization of the product outside the United States.

The company continued to broaden its portfolio through business development. It also reached an agreement to acquire Mersana Therapeutics, adding antibody-drug conjugate technology to its pipeline. Meanwhile Day One pursued confirmatory studies for Ojemda, including a Phase 3 trial in newly diagnosed patients, and grew product revenue after launch.

In early 2026, Day One entered into a merger agreement with Servier, an independent French pharmaceutical group headquartered in the Paris area and governed by a foundation. Under the agreement, Servier launched a cash tender offer for all outstanding shares of Day One common stock at $21.50 per share, implying an equity value of roughly $2.5 billion. The transaction gave Servier an expanded oncology presence, including a marketed pediatric brain tumor therapy.

Following completion of the tender offer, the merger closed and Day One became a wholly owned subsidiary of Servier. A Form 25 relating to Day One common stock was filed with the SEC on April 23, 2026, and the shares stopped trading on Nasdaq. Former shareholders received the cash merger consideration, and the company no longer files periodic reports as an independent public company.