Association of PD-L1 combined positive score with efficacy of pembrolizumab with or without chemotherapy in R/M HNSCC

The multinational phase 3 KEYNOTE-048 trial randomized patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) 1:1:1 to pembrolizumab alone, pembrolizumab plus chemotherapy, or cetuximab plus chemotherapy. Post-hoc analyses of the study show that pembrolizumab and pembrolizumab-chemotherapy had antitumor activity in the PD L1 combined positive score (CPS) 1-19 subgroup, with pembrolizumab-chemotherapy leading to numerically longer overall survival than cetuximab-chemotherapy. In the PD-L1 CPS < 1 subgroup, neither pembrolizumab nor pembrolizumab chemotherapy demonstrated improvement in overall survival compared with cetuximab-chemotherapy. The authors conclude that although PD-L1 expression is a useful biomarker, additional predictive biomarkers are needed for informing treatment decisions in low PD-L1 expressing R/M HNSCC.