PDCD1 and neoplasm: Dual-checkpoint blockade with nivolumab and ipilimumab (CheckMate 214) utilizes two distinct mechanisms of T-cell activation—reviving exhausted effector cells in the tumor microenvironment via PD-1 inhibition and expanding the pool of tumor-reactive lymphocytes through CTLA-4 blockade, which together yield deep, durable responses and a clear survival plateau in intermediate- and poor-risk patients.