Efficacy of first-line Pembrolizumab plus chemotherapy in de novo metastatic head and neck squamous cell carcinoma

Abstract

We retrospectively evaluated chemotherapy combined with pembrolizumab （C＋PEM） as first-line therapy in 10 patients with head and neck squamous cell carcinoma （HNSCC） who presented with distant metastases at initial diagnosis. The 1-year overall survival and progression-free survival rates were 60％ and 20％, respectively. The overall response rate was 70％ and the disease control rate was 80％, with high response observed in primary tumors, cervical lymph nodes, and distant metastatic sites. Grade 3-4 hematologic toxicities and immune-related adverse events occurred in some patients, but severe complications were limited. The high response rates may reflect early introduction of immune checkpoint inhibition, preservation of primary tumor and regional lymphoid structures supporting antitumor immunity, and chemotherapy-induced tumor antigen release. Mixed responses between sites were observed, suggesting that combining local treatments （surgery or radiotherapy） for ICI-refractory lesions could represent a feasible strategy. Although the cohort is small, these findings support the antitumor activity of C＋PEM in Stage ⅣC HNSCC and underscore the need for larger prospective studies to define patient selection and optimal integration of local and systemic therapies.