SERB Pharmaceuticals Acquires Y-mAbs Therapeutics for $412 Million

SERB Pharmaceuticals entered a merger agreement on August 5, 2025, to acquire Y-mAbs Therapeutics, Inc. (YMAB) for $412 million.

Deal Structure:

SERB will commence an all-cash tender offer to purchase all outstanding shares of Y-mAbs common stock. Holders of Y-mAbs common stock would receive $8.60 per share in cash, representing a premium of 105.25% from the stock’s last close.

Company Profile:

Y-mAbs is a commercial-stage biopharmaceutical company developing and commercializing antibody-based and radioimmunotherapy treatments for cancer, including DANYELZA, the first FDA-approved therapy for relapsed or refractory high-risk neuroblastoma.

SERB Pharmaceuticals is a global specialty pharma company that develops, manufactures, and supplies life‑saving medicines for rare diseases, emergency care, and CBRN preparedness. With over 30 years of experience, SERB delivers essential antidotes and critical therapies—such as Voraxaze, Vistogard, and Xermelo—to healthcare systems, governments, and emergency responders worldwide.

Deal Details and Timeline:

Through this deal, SERB would also be acquiring Y-mAbs’ lead commercial oncology asset, DANYELZA (naxitamab-gqgk). DANYELZA is the first FDA-approved treatment for relapsed or refractory high-risk neuroblastoma, a rare and aggressive pediatric cancer. It received accelerated approval in the United States based on the overall response rate and duration of response.

DANYELZA is indicated for use in pediatric patients aged one year and older, as well as adults, with relapsed or refractory high-risk neuroblastoma in the bone or bone marrow, who have shown a partial response, minor response, or stable disease following prior therapy.

SERB will commence a tender offer by August 19, 2025. The deal is expected to close by the fourth quarter of 2025.

Centerview Partners and Cooley are helping Y-mAbs Therapeutics with financial and legal advice. Meanwhile, Rothschild and Freshfields are doing the same for SERB Pharmaceuticals.

Deal Metrics:

For more comprehensive details about this merger and acquisition transaction, please visit the Deal Metrics page here:

Deal Metrics for the acquisition of Y-mAbs Therapeutics, Inc. (YMAB) by SERB Pharmaceuticals

The Deal Metrics page for each merger or acquisition includes:

• A spread history chart of the merger from the announcement through its completion or failure.
• Progressive events such as the expiration of the HSR period, various regulatory approvals, shareholder votes, etc.
• News and SEC filings.
• A history of deal updates.
• And much more.

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Editor’s Note: Baranjot Kaur contributed to this article