They help maintain self-tolerance by restricting the activity of CD4+ and CD8+ T-cells through various mechanisms, including the secretion of immunosuppressive cytokines such as IL-2, IL-10, IL-35, and TGF-β.96 The presence of Tregs is associated with a dampening of the anti-tumor response, and the ratio of effector T-cells (Teff) to Tregs has been suggested as a predicting factor for the efficacy of ICIs.97 An increased Teff-to-Treg ratio has been correlated with improved responses to these treatments. This evidence concerns the gene IL10 and neoplasm.