Merus' Petosemtamab with Pembrolizumab Interim Data Demonstrates Robust Efficacy and Durability in 1L PD-L1+ r/m HNSCC

Core Insights - Merus N.V. announced interim clinical data for petosemtamab in combination with pembrolizumab, showing a 63% response rate among evaluable patients and a 79% overall survival rate at 12 months [1][2][3] Clinical Data Summary - The ongoing phase 2 trial included 45 patients, with 43 evaluable for efficacy, showing a confirmed overall response rate of 63% (27/43) [3] - The median progression-free survival was reported at 9 months, with a median follow-up of 14.3 months [3] - Among the evaluable patients, 6 achieved complete responses and 21 had partial responses, with responses observed across different PD-L1 levels [3] - The combination treatment was generally well tolerated, with 60% of patients experiencing grade ≥3 treatment-emergent adverse events [3] Future Outlook - The company anticipates sharing top-line interim readouts from one or both phase 3 trials in 2026, indicating a strong belief in the potential of petosemtamab to become a new standard of care for head and neck cancer [2][3]