SERB Pharmaceuticals, a global specialty pharmaceutical company focused on rare diseases and medical emergencies, announced on August 5, 2025, its agreement to acquire Y-mAbs Therapeutics in an all-cash transaction valued at approximately $412 million. The acquisition centers on Y-mAbs' lead commercial asset, DANYELZA (naxitamab-gqgk), the first FDA-approved treatment for relapsed or refractory high-risk neuroblastoma.
Strategic Acquisition Details
Under the merger agreement, SERB will commence a tender offer to purchase all outstanding Y-mAbs shares at $8.60 per share, representing a 105% premium to Y-mAbs' closing price on August 4, 2025. The transaction was unanimously approved by Y-mAbs' Board of Directors following a comprehensive review of strategic alternatives that included discussions with numerous potential buyers for both the company and its individual assets.
"High-risk neuroblastoma is not only a rare and devastating pediatric cancer but also one of the most difficult to treat," said Vanessa Wolfeler, Chief Executive Officer of SERB. "DANYELZA is recognized as a critical treatment option for patients and expands the treatment pathways available to providers in an outpatient setting."
DANYELZA's Clinical Profile
DANYELZA (naxitamab-gqgk) represents a significant therapeutic advancement for neuroblastoma patients. The anti-GD2 therapy received FDA approval under accelerated approval based on overall response rate and duration of response. The drug is indicated, in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), for treating pediatric patients one year of age and older and adult patients with relapsed or refractory high-risk neuroblastoma in the bone or bone marrow who have demonstrated a partial response, minor response, or stable disease to prior therapy.
The therapy's flexibility in administration settings provides important clinical benefits. In addition to inpatient use, physicians can administer DANYELZA in outpatient settings, potentially reducing logistical burdens on patients and their families dealing with this aggressive pediatric cancer.
However, DANYELZA carries significant safety considerations, including a Boxed Warning for serious infusion-related reactions such as cardiac arrest and anaphylaxis, as well as neurotoxicity including severe neuropathic pain and transverse myelitis.
Portfolio Integration and Market Expansion
The acquisition strategically aligns with SERB's existing rare oncology portfolio, which includes Voraxaze (glucarpidase), Vistogard (uridine triacetate), and Xermelo (telotristat ethyl). Jeremie Urbain, Chairman of SERB, emphasized the strategic fit: "DANYELZA is an excellent strategic fit for SERB as it strengthens our existing rare oncology portfolio and will allow us to leverage our existing global footprint and our medical, regulatory, and commercial expertise to expand the reach of DANYELZA to new markets."
Y-mAbs' portfolio extends beyond DANYELZA to include investigational therapies targeting GD2 in solid tumors and CD38 in circulating tumors through ongoing Phase 1 clinical trials using its Self-Assembly DisAssembly (SADA) Pretargeted Radioimmunotherapy Platform (PRIT).
Transaction Timeline and Regulatory Process
SERB is obligated to commence the tender offer by August 19, 2025. The transaction requires satisfaction of customary conditions, including receipt of a majority of Y-mAbs shares in the tender offer and expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act. Y-mAbs stockholders holding approximately 16% of outstanding shares have already entered into tender and support agreements with SERB.
Michael Rossi, President and CEO of Y-mAbs, stated: "Following the thorough process to explore all of the potential paths forward for the Company, we are now moving forward with this agreement with SERB that we believe reflects the most attractive option available to Y-mAbs, providing significant, immediate and certain value to our stockholders."
The transaction is expected to close by the fourth quarter of 2025, after which Y-mAbs stock will no longer be listed on the Nasdaq exchange. The acquisition represents another milestone in SERB's growth strategy following its expansion into the United States five years ago, positioning the company to build a leading global specialty pharmaceutical platform focused on rare diseases and medical emergencies.
