Peripheral T cell cytotoxicity predicts the efficacy of anti-PD-1 therapy for advanced non-small cell lung cancer patients.

Anti-programmed cell death-1 (PD-1) therapy exerts beneficial effects in a limited population of cancer patients. Therefore, more accurate diagnostics to predict the efficacy of anti-PD-1 therapy are desired. The present study investigated whether peripheral T cell cytotoxicity predicts the efficacy of anti-PD-1 therapy for advanced non-small cell lung cancer (NSCLC) patients. Advanced NSCLC patients treated with anti-PD-1 monotherapy (nivolumab or pembrolizumab) were consecutively enrolled in the present study. Peripheral blood samples were subjected to an analysis of peripheral T cell cytotoxicity and flow cytometry prior to the initiation of anti-PD-1 therapy. Peripheral T cell cytotoxicity was assessed using bispecific T-cell engager (BiTE) technology. We found that progression-free survival was significantly longer in patients with high peripheral T cell cytotoxicity (p = 0.0094). In the multivariate analysis, treatment line and peripheral T cell cytotoxicity were independent prognostic factors for progression-free survival. The analysis of T cell profiles revealed that peripheral T cell cytotoxicity correlated with the ratio of the effector memory population in CD4+ or CD8+ T cells. Furthermore, the results of flow cytometry showed that the peripheral CD45RA+CD25+/CD4+ T cell ratio was higher in patients with than in those without severe adverse events (p = 0.0076). These results indicated that the peripheral T cell cytotoxicity predicted the efficacy of anti-PD-1 therapy for advanced NSCLC patients.