Prognosis After Discontinued Treatment due to Immune-Related Adverse Events in Recurrent and Metastatic Head and Neck Squamous Cell Carcinoma.

The prognostic impact of immune-related adverse events (irAEs) in recurrent/metastatic head and neck squamous cell carcinoma (RM-HNSCC) remains unclear, particularly after treatment discontinuation. This retrospective study included RM-HNSCC patients treated with nivolumab or pembrolizumab. The association between irAEs, treatment response, and prognosis was analyzed. To minimize immortal time bias, survival was assessed at multiple time points. Outcomes after permanent discontinuation due to irAEs were also evaluated. Among 92 cases, 25 cases (27.2%) experienced irAEs. Cases that experienced irAEs showed better progression-free survival than those who did not experience irAEs. Eight cases permanently discontinued treatment due to irAEs, and six cases maintained tumor shrinkage after discontinuing ICI. In this study, irAEs were associated with a good prognosis. Furthermore, it was revealed that many of the cases in which treatment was permanently discontinued due to irAEs continued a durable response even after treatment ended.