Genmab’s petosemtamab plus Merck’s Keytruda delivered a late-stage success in first-line head and neck squamous cell carcinoma, driving a sharp rally in the stock and underscoring the company’s multi-asset growth plan. At an early analysis, the combination cut the risk of death by half versus Keytruda alone in patients whose tumors test positive for PD-L1. Genmab said the regimen met its main objectives for response rates and survival in the study, building on earlier Phase 2 signals for petosemtamab, a bispecific antibody targeting EGFR and LGR5. The company also positioned the data as part of a streak of late-stage readouts in recent weeks, including wins in lymphoma and ovarian cancer from other programs in its pipeline. The company plans to share detailed results with global regulators and present at an upcoming medical meeting. Analysts cited the new head and neck data as an important potential standard-of-care contender ahead of the patent expiry for Darzalex exclusivity that is expected to pressure the company’s Darzalex franchise. Genmab noted it acquired petosemtamab as part of its Merus buyout and that it earns royalties tied to J&J’s commercial rights to Darzalex, highlighting how near-term clinical momentum is expected to offset future revenue headwinds.