Danish biotechnology company Genmab A/S (CPH:GMAB) on Monday reported updated Phase 2 results showing median overall survival of 28.2 months with investigational petosemtamab plus pembrolizumab in first-line treatment of recurrent or metastatic PD-L1-positive head and neck squamous cell carcinoma (HNSCC).

Among 43 efficacy-evaluable patients, the combination achieved an overall response rate of 63%, a complete response rate of 19% and median progression-free survival of 9.0 months, with responses observed across HPV-positive and HPV-negative disease subgroups.

As of 15 May 2026, median follow-up was 25.5 months, and the estimated 12-month overall survival rate was 79%; median duration of response had not been reached, with an estimated 55% of responders maintaining their response at 24 months.

The most common treatment-emergent adverse events were asthenia and acneiform dermatitis, each reported in 51% of patients, and rash in 49%; no Grade 5 adverse events or treatment-related deaths were reported.

The findings were presented at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid.

Genmab's Phase 3 LiGeR-HN1 trial evaluating the combination in first-line PD-L1-positive recurrent or metastatic HNSCC is ongoing, with topline data anticipated later this year.

Petosemtamab is an investigational bispecific antibody targeting EGFR and LGR5, and its clinical development programme includes four Phase 3 trials across head and neck and colorectal cancers.