Day One to Acquire Mersana Therapeutics to Advance Mission to Bring New Medicines to People of All Ages with Life-Threatening Diseases
Day One (NASDAQ: DAWN) signed a definitive merger agreement to acquire Mersana Therapeutics for $25 per share cash plus one non-tradable CVR, with total consideration up to $55.25 per share and an approximate equity value at closing of $129 million (total deal value up to ~$285 million). The acquisition adds emiltatug ledadotin (Emi-Le), an antibody‑drug conjugate targeting B7-H4, which showed early anti-tumor activity in an ongoing Phase 1 study for adenoid cystic carcinoma type‑1 (ACC‑1).
Milestone CVR payments total up to $30.25 per share tied to clinical, regulatory, and sales milestones. Day One expects to fund the transaction with existing cash and aims to close by end of January 2026, subject to regulatory approvals and customary conditions.
Day One (NASDAQ: DAWN) ha firmato un accordo definitivo di fusione per acquisire Mersana Therapeutics per $25 per azione in contanti più un CVR non negoziabile, con una controparte totale fino a $55.25 per azione e un valore azionario approssimativo al closing di $129 milioni (valore totale dell'affare fino a ~$285 milioni). L'acquisizione aggiunge emiltatug ledadotin (Emi-Le), un conjugato anticorpo‑farmaco che punta a B7-H4, che ha mostrato attività antitumorale precoce in uno studio di Fase 1 in corso per il carcinoma adenoide cistico tipo‑1 (ACC‑1).
I pagamenti CVR legati a milestone ammontano a un massimo di $30.25 per azione, legati a traguardi clinici, regolatori e di vendita. Day One prevede di finanziare l'operazione con liquidità esistente e punta a chiudere entro la fine di gennaio 2026, soggetta ad approvazioni regolamentari e condizioni consuete.
Day One (NASDAQ: DAWN) firmó un acuerdo definitivo de fusión para adquirir Mersana Therapeutics por $25 por acción en efectivo más un CVR no negociable, con una contraprestación total de hasta $55.25 por acción y un valor de capitalización aproximadamente en el cierre de $129 millones (valor total del trato hasta ~$285 millones). La adquisición añade emiltatug ledadotin (Emi-Le), un conjugado anticuerpo‑droga que apunta a B7-H4, que mostró actividad antitumoral temprana en un ensayo de Fase 1 en curso para el carcinoma adenoide quístico tipo‑1 (ACC‑1).
Los pagos de CVR por hitos totalizan hasta $30.25 por acción vinculados a hitos clínicos, regulatorios y de ventas. Day One espera financiar la operación con efectivo existente y apunta a cerrar para finales de enero de 2026, sujeto a aprobaciones regulatorias y condiciones habituales.
Day One (NASDAQ: DAWN)은 Mersana Therapeutics를 주당 $25 현금 + 비거래 가능한 CVR로 인수하는 확정 합병 계약을 체결했으며, 총 보상은 주당 최대 $55.25이고 클로징 시점의 주당 가치는 약 $129백만 (총 거래가 약 ~$285백만)에 이릅니다. 이번 인수로 B7-H4를 표적하는 항체-약물 결합체인 emiltatug ledadotin(Emi-Le)이 추가되며, 이 물질은 진행 중인 1상 연구에서 점막 세포종 ACC-1 유형의 초기 항종양 활성을 보였습니다.
마일스톤 CVR 지급은 임상, 규제 및 판매 마일스톤과 연계되어 주당 $30.25까지 총합계됩니다. Day One은 현금 보유로 거래를 자금 조달할 예정이며, 2026년 1월 말까지 마감하는 것을 목표로 하되 규제 승인 및 일반 조건에 따릅니다.
Day One (NASDAQ: DAWN) a signé un accord de fusion définitif pour acquérir Mersana Therapeutics pour $25 par action en espèces plus un CVR non négociable, avec une contrepartie totale jusqu'à $55.25 par action et une valeur d'équité approximative à la clôture de $129 millions (valeur totale de l'accord jusqu'à environ $285 millions). L'acquisition ajoute emiltatug ledadotin (Emi-Le), un conjugué anticorps‑médicament ciblant B7-H4, qui a montré une activité antitumorale précoce dans une étude de phase 1 en cours pour le type‑1 carcinome adénoïde kystique (ACC‑1).
Les paiements CVR d'étape totalisent jusqu'à $30.25 par action liés à des jalons cliniques, réglementaires et de ventes. Day One prévoit de financer l'opération avec les liquidités existantes et vise à boucler d'ici la fin janvier 2026, sous réserve des approbations réglementaires et des conditions habituelles.
Day One (NASDAQ: DAWN) hat eine endgültige Fusionsvereinbarung zum Erwerb von Mersana Therapeutics für $25 pro Aktie in bar plus ein nicht handelbarer CVR unterzeichnet, mit einer Gesamtprämie von bis zu $55.25 pro Aktie und einem ungefähren Eigenkapitalwert zum Schluss von $129 Millionen (Gesamttransaktionswert bis ca. $285 Millionen). Die Übernahme fügt emiltatug ledadotin (Emi-Le) hinzu, ein Antikörper‑Drogen‑Zusammenschluss, der B7-H4 zielt und in einer laufenden Phase‑1-Studie für Adenoidzystisches Karzinom Typ‑1 (ACC‑1) eine frühe antitumorale Aktivität zeigte.
Meilenstein‑CVR‑Zahlungen betragen insgesamt bis zu $30.25 pro Aktie, gebunden an klinische, regulatorische und Verkaufsmeilensteine. Day One plant, die Transaktion mit vorhandenen Barmitteln zu finanzieren und beabsichtigt, bis Ende Januar 2026 abzuschließen, vorbehaltlich behördlicher Genehmigungen und üblicher Bedingungen.
Day One (NASDAQ: DAWN) وقعت اتفاقية اندماج نهائية للاستحواذ على Mersana Therapeutics مقابل $25 للسهم نقداً بالإضافة إلى CVR غير قابل للتداول، مع تعويض إجمالي يصل إلى $55.25 للسهم وقيمة حقوق الملكية التقريبية عند الإغلاق تبلغ $129 مليون (إجمالي قيمة الصفقة حتى نحو $285 مليون). يضيف الاستحواذ Emi‑Le، وهو مركّب مضاد للجسم-دواء يستهدف B7-H4، والذي أظهر نشاطاً مضاداً للأورام مبكراً في دراسة من المرحلة 1 جارية لسرطان الغدة اللعابية الأنبوبي النخاعي النوع 1 ACC-1.
مدفوعات CVR عند الإنجازات تصل إلى ما يصل حتى $30.25 للسهم مرتبطة بالإنجازات السريرية والتنظيمية والمبيعات. Day One تتوقع تمويل الصفقة من النقد المتوفر وتهدف إلى الإغلاق بحلول نهاية يناير 2026، رهناً بموافقات تنظيمية وظروف اعتيادية.
- Adds Emi-Le ADC targeting B7-H4 with Phase 1 anti-tumor activity
- Total deal value up to $285 million
- Equity value at closing of ~$129 million
- CVR structure aligns payments to clinical/regulatory/sales milestones
- Day One expects to fund the acquisition with existing cash
- Full consideration depends on CVR milestones totaling up to $30.25 per share
- Transaction closing is subject to regulatory approvals and customary conditions
- Milestone payments contingent on regulatory approval and commercial sales targets
Insights
Acquisition adds a novel ADC candidate and a defined commercial path; financing expected from cash, closing targeted by
Day One expands its oncology portfolio by acquiring Mersana and the ADC emiltatug ledadotin (Emi‑Le), reported to show early monotherapy anti‑tumor activity in an ongoing Phase 1 study for adenoid cystic carcinoma type‑1 (ACC‑1). The deal terms include a cash tender offer of
The acquisition’s business mechanism is clear: Day One acquires an investigational asset with a stated potential registration path and consolidates development and commercial responsibilities. The payment structure links value to development, regulatory and sales milestones, including a
Key dependencies and risks are explicit in the terms: Emi‑Le’s future value depends on clinical progress from Phase 1 into a registrational trial, regulatory approvals, and future commercial sales thresholds. The CVR ties meaningful downstream payments to uncertain milestones such as dosing in a registrational trial and FDA approval. The transaction also remains subject to customary closing conditions and regulatory approvals, with a target close by
Concrete items to watch include initiation and enrollment progress of a registrational Emi‑Le trial and any FDA designation decisions (the CVR lists a Breakthrough Therapy milestone), plus reported clinical readouts and timing toward the stated close by
Acquisition expands Day One’s portfolio with novel antibody-drug conjugate (ADC) emiltatug ledadotin (Emi-Le)
Emi-Le has demonstrated early anti-tumor activity in an ongoing Phase 1 study for adenoid cystic carcinoma type-1 (ACC-1), a cancer with high unmet need and a lack of therapeutic options
Day One will apply existing scientific and commercial capabilities to this investigational innovative therapeutic with a clear potential registration path
Company to host conference call and webcast today, November 13, 8:00 am Eastern Time
BRISBANE, Calif., Nov. 13, 2025 (GLOBE NEWSWIRE) -- Day One Biopharmaceuticals, Inc. (Nasdaq: DAWN) (“Day One” or the “Company”), a biopharmaceutical company dedicated to developing and commercializing targeted therapies for people of all ages with life-threatening diseases, today announced it has signed a definitive merger agreement for Day One to acquire Mersana Therapeutics (“Mersana”).
The transaction positions the Company for continued success and expansion of its oncology portfolio, adding Emi-Le, a potential first-in-class monotherapy for patients with ACC, an aggressive cancer with a well-defined patient population and high unmet need, most often arising from the salivary gland. The early anti-tumor activity observed with Emi-Le in an ongoing Phase 1 study, in a disease with a clear unmet medical need, may support a fast path to registration. Emi-Le represents an innovative and differentiated ADC directed against B7-H4, a well-characterized target in certain cancers. B7-H4 is highly expressed in ACC as well as in other adult and pediatric cancers. As a novel targeted investigational agent with monotherapy anti-tumor activity intended for a well-defined patient population without any approved therapies or a clear standard of care, the Company believes that Emi-Le is well positioned for potential rapid development and commercialization.
“This acquisition will add a potential game-changing new medicine to the Day One portfolio and, if approved, will broaden our opportunities for patient impact and for continued growth and value creation,” said Jeremy Bender, Ph.D., chief executive officer of Day One. “The addition of the Emi-Le program to our portfolio allows us to leverage the research and development expertise, and the commercial capabilities, that already exist within Day One to address underserved, rare and life-threatening cancers in patients of all ages.”
Terms of the Agreement
Under the terms of the definitive merger agreement, Day One will promptly commence a tender offer to acquire all of the outstanding shares of Mersana common stock at a price of
Clinical Milestones
- A development milestone related to an existing partnership agreement:
$1.25 per share - Breakthrough Therapy Designation for ACC granted by FDA:
$1.00 per share - First dosing of a participant in a of registrational trial of Emi-Le for ACC-1:
$4.00 per share
Regulatory/Sales Milestones
- Regulatory approval granted by FDA in Emi-Le ACC-1:
$9.00 per share - First commercial sale of Emi-Le in a major EMA markets:
$2.00 per share - First commercial sale of Emi-Le in Japan:
$1.00 per share - Annual net sales of Emi-Le exceed
$100 million by 2032:$2.00 per share - Annual net sales of Emi-Le exceed
$200 million by 2035:$4.00 per share - Annual net sales of Emi-Le exceed
$300 million by 2037:$6.00 per share
Day One expects to finance the acquisition with existing cash resources. Day One’s strong cash position and financial profile is expected to enable development of Emi-Le through potential approval with no additional financing required.
The transaction is expected to close by the end of January 2026, subject to receipt of applicable regulatory approvals and the satisfaction of other customary conditions.
Advisors
Gordon Dyal & Co., LLC is acting as the exclusive financial advisor to Day One, with Fenwick & West LLP serving as legal counsel. TD Cowen is acting as financial advisor to Mersana, with Wilmer Cutler Pickering Hale and Dorr LLP serving as legal counsel.
Conference Call
Day One will host a conference call and webcast today, Nov. 13 at 8:00 am Eastern Time. To access the live conference call by phone, dial 877-704-4453 (domestic) or 201-389-0920 (international), and provide the access code 13757215. Live audio webcast will be accessible from the Events page. To ensure a timely connection to the webcast, it is recommended that participants register at least 15 minutes prior to the scheduled start time. An archived version of the webcast will be available for replay on the Events section of the Day One Media & Investors page for 30 days following the event.
About Day One Biopharmaceuticals
Day One Biopharmaceuticals is a commercial-stage biopharmaceutical company that believes when it comes to pediatric cancer, we can do better. The Company was founded to address a critical unmet need: the dire lack of therapeutic development in pediatric cancer. Inspired by “The Day One Talk” that physicians have with patients and their families about an initial cancer diagnosis and treatment plan, Day One aims to re-envision cancer drug development and redefine what’s possible for all people living with cancer—regardless of age—starting from Day One.
Day One partners with leading clinical oncologists, families, and scientists to identify, acquire, and develop important targeted cancer treatments. The Company’s pipeline includes tovorafenib (OJEMDA™) and DAY301.
Day One is based in Brisbane, California. For more information, please visit www.dayonebio.com or find the Company on LinkedIn or X.
About Mersana Therapeutics
Mersana Therapeutics is a clinical-stage biopharmaceutical company focused on the development of novel antibody drug conjugates (ADCs) and driven by the knowledge that patients are waiting for new treatment options. The company has developed proprietary cytotoxic (Dolasynthen) and immunostimulatory (Immunosynthen) ADC platforms that have generated a pipeline of wholly-owned and partnered product candidates with the potential to treat a range of cancers. Its pipeline includes Emi-Le (emiltatug ledadotin; XMT-1660), a Dolasynthen ADC targeting B7-H4, and XMT-2056, an Immunosynthen ADC targeting a novel epitope of human epidermal growth factor receptor 2 (HER2). Mersana routinely posts information that may be useful to investors on the “Investors & Media” section of its website at www.mersana.com.
Additional Information about the Transaction and Where to Find It
The tender offer described in this communication (the Offer) has not yet commenced, and this communication is neither a recommendation, nor an offer to purchase nor a solicitation of an offer to sell any shares of the common stock of Mersana or any other securities. On the commencement date of the Offer, a tender offer statement on Schedule TO, including an Offer to Purchase, a Letter of Transmittal and related documents, will be filed with the U.S. Securities and Exchange Commission (SEC) by Day One and Emerald Merger Sub, Inc. (Purchaser), and a Solicitation/Recommendation Statement on Schedule 14D-9 will be filed with the SEC by Mersana. The offer to purchase shares of Mersana common stock will only be made pursuant to the offer to purchase, the letter of transmittal and related documents filed as a part of the Schedule TO. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ BOTH THE TENDER OFFER STATEMENT AND THE SOLICITATION/RECOMMENDATION STATEMENT REGARDING THE OFFER, AS THEY MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME, WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION THAT INVESTORS AND SECURITY HOLDERS SHOULD CONSIDER BEFORE MAKING ANY DECISION REGARDING TENDERING THEIR COMMON STOCK, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER. Investors and security holders may obtain a free copy of these statements (when available) and other documents filed with the SEC at Day One’s website at ir.dayonebio.com and (once they become available) will be mailed to the stockholders of Mersana free of charge. The information contained in, or that can be accessed through, Day One’s website is not a part of, or incorporated by reference in, this filing. The tender offer materials (including the Offer to Purchase and the related Letter of Transmittal), as well as the Solicitation/Recommendation Statement, will also be made available for free on the SEC’s website at www.sec.gov. In addition to the Offer to Purchase, the related Letter of Transmittal and certain other tender offer documents, as well as the Solicitation/Recommendation Statement, Day One and Mersana file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read any reports, statements or other information filed by Mersana and Day One with the SEC for free on the SEC’s website at www.sec.gov.
Cautionary Note Regarding Forward-Looking Statements
This communication contains forward-looking statements. Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “intends”, “estimates”, “plans”, “will”, “goal” and similar expressions. These forward-looking statements include, without limitation, statements related to the anticipated consummation of the acquisition of Mersana and the expected benefits therefrom; and other statements that are not historical facts. These forward-looking statements are based on Day One’s current expectations and inherently involve significant risks and uncertainties. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation, risks related to Day One’s ability to complete the transaction on the proposed terms and schedule, or at all; whether the various conditions to the consummation of the transaction under the merger agreement will be satisfied or waived; whether stockholders of Mersana tender sufficient shares in the transaction; the occurrence of any event, change or other circumstance that could give rise to the termination of the merger agreement; the outcome of legal proceedings that may be instituted against Day One, Mersana and/or others relating to the transaction and the risk that such legal proceedings may result in significant costs of defense, indemnification and liability; the failure (or delay) to receive the required regulatory approvals relating to the transaction; the possibility that competing offers will be made; disruption from the proposed transaction, making it more difficult to conduct business as usual or maintain relationships with customers, employees or suppliers; the risk that Day One will not be able to retain the employees of Mersana following the closing of the transaction given the at-will nature of their employment; risks associated with acquisitions, such as the risk that the businesses will not be integrated successfully, that such integration may be more difficult, time-consuming or costly than expected or that the expected benefits of the transaction will not occur; risks associated with developing product candidates; risks and uncertainties related to unforeseen delays that may impact the timing of clinical trials and reporting data; risks related to future opportunities and plans for Mersana and its product candidates, including uncertainty of the expected financial performance of Mersana and its product candidates and the possibility that the milestone payments related to the contingent value right will never be achieved and that no milestone payment may be made; the possibility that if Day One does not achieve the perceived benefits of the proposed transaction as rapidly or to the extent anticipated by financial analysts or investors, the market price of Day One’s shares could decline; as well as other risks related to Day One’s and Mersana’s businesses detailed from time-to-time under the caption “Risk Factors” and elsewhere in Day One’s and Mersana’s respective SEC filings and reports, including their respective Annual Reports on Form 10-K for the year ended December 31, 2024 and subsequent quarterly and current reports filed with the SEC. Day One undertake no duty or obligation to update any forward-looking statements contained in this communication as a result of new information, future events or changes in their expectations, except as required by law.
DAY ONE MEDIA
Laura Cooper, Head of Communications
media@dayonebio.com
DAY ONE INVESTORS
LifeSci Advisors, PJ Kelleher
pkelleher@lifesciadvisors.com
FAQ
What price is Day One (DAWN) offering to acquire Mersana on November 13, 2025?
How much is the deal for Day One (DAWN) worth in total and at closing?
What milestones must Mersana achieve to receive CVR payments after the DAWN acquisition?
What is Emi-Le and why is it material to Day One (DAWN)?
When does Day One (DAWN) expect to close the Mersana acquisition?
Will Day One (DAWN) need new financing to complete the acquisition?
