PDCD1 and melanoma: This is consistent with observations on a B16 melanoma mouse model in which iNKT cells displayed dysfunctional states with increased expression of the exhaustion markers (PD1, CTLA4, and TIM3) and of NKG2D, as well as a low level of IFNγ production associated with IL-4, IL-10, and IL-17 production in the TME (23).