Background
Immune checkpoint inhibitors (ICIs), including nivolumab, have been approved to treat esophageal cancer. However, these remedies are not fit for all patients with esophageal cancer; therefore, a predictive surrogate marker is needed to assess their effectiveness. CD103+CD8+ tumor-infiltrating lymphocytes, defined as tissue-resident memory T cells (TRM), are promising indicators of response to ICIs, but it remains to be elucidated. This study investigated the association between the efficacy of ICIs and TRM.
Methods
The relationships between TRM infiltrating esophageal cancer, clinicopathological features, and prognosis after nivolumab initiation were examined using immunostaining. Tissue samples were obtained from surgically resected specimens of 41 patients with esophageal cancer who received nivolumab as a secondary or subsequent therapy. In addition, TRM infiltration was compared with programmed death-ligand 1 (PD-L1) expression and blood count parameters as predictors of nivolumab effectiveness.
Results
TRM-rich patients had a significant survival benefit after nivolumab initiation and experienced immune-related adverse events more frequently than TRM-poor patients. TRM infiltration was weakly correlated with PD-L1 positivity, but TRM may indicate more sensitive response to ICIs than PD-L1 expression in this study. Some blood test parameters also weakly correlated with TRM but did not impact prognosis.
Conclusions
TRM-rich patients have a favorable prognosis after nivolumab initiation. Our results suggest that TRM are vital for antitumor immunity and are a promising predictor of ICIs effectiveness.