ICOS and neoplasm: Furthermore, an increased proportion of IFN-γ-producing CD4+ICOS+ T cells was sequentially observed in peripheral blood and tumor tissue after patients received anti-CTLA-4 therapy for bladder cancer, prostate tumors and metastatic melanoma, which was closely associated with clinical benefits and could serve as a specific pharmacodynamic indicator to monitor the efficacy of anti-CTLA-4 therapy (90–93).