Survival impact of sequential chemotherapy following pembrolizumab for recurrent or metastatic head and neck squamous cell carcinoma

Background Pembrolizumab alone or combined with chemotherapy is the standard of care for first-line treatment of patients with recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) with positive programmed death-ligand 1 combined positive scores. However, data on second-line chemotherapy following pembrolizumab are scarce. Methods A single-center, retrospective study was conducted to determine the efficacies of pembrolizumab and pembrolizumab plus chemotherapy as first-line treatments and the efficacy of second-line chemotherapy for patients with R/M HNSCC who were refractory or intolerant to first-line treatment. Results Fifty-four patients were treated with pembrolizumab, and 29 received second-line therapy, with 27 opting for cetuximab-containing regimens. The median progression-free survival (PFS), overall survival (OS), and PFS on next-line therapy for first-line treatment were 4.7 (95% confidence interval [CI], 2.1–8.7), 22.1 (95% CI, 12.6–not reached), and 15.6 months (95% CI, 9.7–not reached) in the pembrolizumab group and 5.4 (95% CI, 3.3–6.8), 15.8 (95% CI, 8.6–not reached), and 13.7 months (95% CI, 8.1–not reached) in the pembrolizumab plus chemotherapy group, respectively. The overall response rate and median PFS for second-line treatment were 48.3% (95% CI, 30.4–67.0) and 6.1 months (95% CI, 2.30–8.84). The median OS for patients who received second-line treatment was 18.4 months, which was superior to the median OS of 6.0 months for patients who received the best supportive care (log-rank p = 0.10). Conclusion This study indicates that cetuximab-containing second-line chemotherapy can improve outcomes in R/M HNSCC, even after first-line therapy failure or intolerance.