Studies in mouse models showed that the addition of metformin to nivolumab increased CD8 + tumor-infiltrating lymphocytes and decreased the production of interleukin 2 (IL-2), tumor necrosis factor (TNF), and interferon-gamma (IFN-γ) and, altogether, this protects lymphocytes from apoptosis and exhaustion. The gene discussed is IL2; the disease is neoplasm.