Peripheral eosinophils and immunotherapy response in patients with recurrent or metastatic HNSCC

This study investigates the relationship between absolute eosinophil count (AEC) and eosinophil percentage (EOS%) with response rates to immune checkpoint inhibitors (ICIs) in recurrent or metastatic head and neck squamous cell carcinoma (R/M HNSCC) patients. The analysis included data from R/M HNSCC patients treated with ICIs at Second Xiangya Hospital (2016-2021), assessing baseline characteristics, tumor specifics, immune-related adverse events, AEC, and EOS%. The correlation between these factors and ICI response rates was evaluated using logistic regression, while survival outcomes were analyzed through Kaplan-Meier curves and Cox models. Among 74 patients, 59 had low AEC and 15 high, with 53 presenting low EOS% and 21 high. Low AEC (44.07% response rate) and EOS% (47.17%) yielded better responses compared to high levels (40% and 33.33%, respectively). Median overall survival was longer for low AEC (22.63 vs. 18.00 months, P < 0.001) and low EOS% (22.07 vs. 19.73 months, P = 0.02). Both low AEC and EOS% correlated with improved survival odds (3.85 and 2.41 times respectively). Lower AEC and EOS% are independently linked to better survival and increased ICI response rates in R/M HNSCC patients, indicating their potential as predictors for ICI treatment outcomes.