Genmab's petosemtamab cuts death risk by 50% in Phase 3 head and neck cancer trial

What's the deal? Genmab announced on 28 October 2026 that its investigational antibody petosemtamab, given alongside pembrolizumab (Merck & Co.'s checkpoint inhibitor Keytruda), met both primary endpoints of the Phase 3 LiGeR-HN1 trial in people with previously untreated, PD-L1-positive recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). At the first interim analysis, the combination cut the risk of death by 50% compared with pembrolizumab alone (overall survival hazard ratio 0.50; 95% CI 0.37-0.67; p