Interferon-γ Production by Peripheral Lymphocytes Predicts Survival of Tumor-Bearing Mice Receiving Dual PD-1/CTLA-4 Blockade.

Immune checkpoint inhibitors are transforming the way cancer is treated. However, these therapies do not benefit all patients and frequently cause significant immune-related adverse events. Biomarkers that identify patients with a favorable early response to therapy are essential for guiding treatment decisions and improving patient outcomes. In this report of our study, we present evidence that shortly after administration of dual PD-1/CTLA-4 blockade, the proinflammatory capacity of peripheral lymphocytes is predictive of tumor progression and survival outcomes in multiple murine models. Specifically, we observed that the quantity of interferon-γ (IFNγ) produced by peripheral lymphocytes in response to CD3/CD28 stimulation was robustly correlated with subsequent survival outcomes. In the tumor models and early time points assessed in this study, this relationship was considerably more predictive than a host of other potential biomarkers, several of which have been previously reported. Overall, these findings suggest that measuring the capacity of peripheral lymphocytes to produce IFNγ may help identify which patients are benefitting from combination anti-PD-1/anti-CTLA-4 immunotherapy. Cancer Immunol Res; 4(8); 650-7. ©2016 AACR.