Genmab has finalized an $8 billion all-cash acquisition of Dutch biotech Merus, securing rights to its phase III-stage bispecific antibody, petosemtamab, targeting head and neck cancer. Petosemtamab, combined with Merck’s Keytruda, showed preliminary survival benefits in metastatic head and neck cancer during a phase 2 trial. The acquisition accelerates Genmab’s transition to a fully integrated biopharma with ownership of late-stage assets. Full ownership of petosemtamab enhances Genmab’s oncology pipeline amid an impending patent cliff for its blockbuster drug Darzalex.