CTLA4 and metastatic melanoma: Elevated evidences indicated that blocked the cytotoxic T lymphocyte associated protein 4 (CTLA4), and programmed death 1 (PD-1) or its ligand PD-L1 had demonstrated unparalleled therapeutic efficacy in cancers such as non-small cell lung cancer, metastatic melanoma and bladder cancer (Snyder et al., 2014; Garon et al., 2015).