Merus N.V. announced interim phase 2 trial data for petosemtamab combined with pembrolizumab in treating head and neck squamous cell carcinoma (HNSCC). The combination therapy demonstrated a 63% overall response rate among 43 evaluable patients, with a 79% overall survival rate at 12 months and a median progression-free survival of 9 months. The data was presented at the 2025 American Society of Clinical Oncology Annual Meeting.
These interim results are notable because they suggest a potential improvement over existing treatments for HNSCC, a cancer type associated with poor prognosis and high mortality. The high overall response rate and promising survival data could position petosemtamab, if approved, as a new standard of care for this challenging cancer. This could significantly improve patient outcomes and change clinical practice in the field of head and neck oncology.
The phase 2 trial data, with a cutoff date of February 27, 2025, includes 45 treated patients with a median follow-up of 14.3 months. Among the 43 evaluable patients, the confirmed overall response rate was 63%, which includes six complete and 21 partial responses. The combination therapy was generally well-tolerated, with no significant overlapping toxicities with pembrolizumab observed. Adverse events were reported in most patients, but serious (Grade 3 or higher) treatment-related adverse events occurred in less than half.
This positive interim data strengthens the potential of petosemtamab as a viable treatment option for HNSCC. Further results from the ongoing phase 3 trials, expected in 2026, will be crucial in confirming the efficacy and safety profile of this combination therapy. Positive results from these trials could lead to regulatory approval and significantly impact the treatment landscape for head and neck cancer.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
