Long-term Outcomes and Mixed Response in Nivolumab Therapy for Head and Neck Cancer

This study aimed to explore the long-term outcomes of patients with recurrent/metastatic head and neck cancer (RM-HNC) treated with nivolumab in a real-world setting. We retrospectively analyzed 53 patients with R/M-HNC treated with nivolumab between 2017 and 2024 at the Shinshu University Hospital. Clinical data included response rates, overall survival (OS), progression-free survival 1 (PFS1) 1, PFS2, and immune-related adverse events (irAEs). The median OS was 18.1 months, with 1-year, 2-year, and 4-year survival rates of 57.7%, 37.9%, and 23.3%, respectively. Mixed response (MR) was observed in 17% of patients, and these patients showed significantly better OS than those with progressive disease (p=0.007). Notably, nivolumab was effective in patients not included in the CheckMate 141 criteria, especially in those with nasopharyngeal carcinoma (NPC) showing a favorable prognosis (median OS: 44.0 months). Overall, 13 patients experienced irAEs (24.5%), although this did not significantly affect OS (p=0.170). Long-term survival was observed in 13 patients, with 69.2% of them achieving either complete response or partial response. This study provides new insights into the long-term efficacy of nivolumab in R/M-HNC, highlighting the favorable prognosis in NPC and in patients outside the CheckMate 141 criteria. Importantly, this study is the first to report the frequency of MR in HNC, with MR being associated with a significantly better prognosis.