PDCD1 and neoplasm: The co-expression of other inhibitory immune-checkpoint molecules, such as TIM-3 (T-cell immunoglobulin and mucin domain-containing protein 3) and lymphocyte-activating gene 3 (LAG-3), has also been shown to impair immune T-cell-mediated responses, conferring resistance to anti-PD-1/PD-L1 agents in preclinical models and in patients across different tumor types.