Association of the CD4/CD8 ratio with response to PD-1 inhibitor-based combination therapy and dermatological toxicities in patients with advanced gastric and esophageal cancer.

The host immune system affects the treatment response to immune checkpoint inhibitors and can be reflected by circulating immune cells. This study aimed to evaluate whether circulating T cell subtypes are correlated with clinical response and dermatological toxicities in patients with advanced gastric and esophageal cancer receiving PD-1 inhibitor-based combination therapy (n = 203). In the training cohort, Eastern Cooperative Oncology Group performance status (ECOG PS), PD-L1 expression, antibiotic use, and CD4/CD8 ratio were identified as independent prognostic factors in these patients, using a Cox regression model.