Early progression after immune checkpoint inhibitor therapy in recurrent or metastatic head and neck squamous cell carcinoma: association with disease distribution in a single-center retrospective study.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are an important treatment option for recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC). However, some patients experience rapid disease progression shortly after ICI initiation, potentially resulting in deterioration of general condition and limited opportunities for subsequent treatment. This study investigated clinicopathological factors associated with early progression after ICI initiation in patients with R/M HNSCC. METHODS: We retrospectively analyzed 207 patients with R/M HNSCC treated with nivolumab or pembrolizumab at a single institution. Early progression was defined as disease progression within 90 days after ICI initiation. Associations between clinicopathological factors and early progression were evaluated using logistic regression analyses. RESULTS: Early progression was observed in 80 patients (38.6%). In an exploratory survival comparison, patients with early progression had significantly shorter overall survival than those without early progression. Early progression rates increased from distant-only disease to locoregional-only disease and combined locoregional and distant disease. In multivariable analysis, combined locoregional, and distant disease showed the strongest independent association with early progression. Elevated neutrophil-to-lymphocyte ratio and hypoalbuminemia were also independently associated with early progression. In contrast, treatment regimen, treatment line, number of lesions, and bulky disease were not significantly associated with early progression. CONCLUSION: Disease distribution was associated with early progression after ICI initiation in patients with R/M HNSCC, with combined locoregional and distant disease showing the strongest independent association. These findings suggest that both disease status and host condition may influence failure to achieve adequate disease control shortly after ICI initiation.