Genmab makes $8bn acquisition to boost late-stage antibody therapy pipeline

Genmab has agreed to acquire Netherlands-based biotech Merus for approximately $8 billion, giving it rights to late-stage breakthrough cancer therapy petosemtamab.

The proposed deal aligns with Genmab’s focus on antibody therapy development and commercialisation in oncology and is anticipated to support the company in shifting to a wholly owned model, strengthening its revenue base and supporting its growth into 2030.

Petosemtamab is an EGFRxLGR5 bispecific antibody with potential as a first- and best-in-class drug in both head and neck cancer, according to Merus. Phase II data presented at the American Society for Clinical Oncology (ASCO) 2025 Annual Meeting showed both “substantially higher” overall response rate and median progression free survival compared to standard of care.

Two phase III trials are currently evaluating petosemtamab in first- and second/third line head and neck cancer. Merus plans to share topline interim data for one or both trials next year.

Under the acquisition agreement, the Denmark-based biotech Genmab also aims to advance petosemtamab for potential expansion into earlier lines of therapy.

Furthering development of petosemtamab in oncology and beyond

Dr Bill Lundberg, President and Chief Executive Officer of Merus, said: “We are excited for the opportunity to join Genmab, a leader in antibody therapeutics, to further develop and bring petosemtamab to patients. 

“Our two companies have a rich history of innovation with multiple approvals in the field of multi-specific antibodies. We believe Genmab has the right vision and experience to advance petosemtamab in recurrent/metastatic head and neck cancer and beyond.”

The deal is expected to be finalised early in the first quarter of 2026, at which point Genmab says it will have four proprietary programmes that are expected to drive multiple new drug launches by 2027.