PDCD1 and melanoma: Anti-PD-1-blockade Ab along with poly (I:C) treatment regressed the established mouse melanomas, and increased survival time when compared to poly (I:C) treatment alone (126 ± 16 vs. 97 ± 13 days). But anti–PD-1 Ab alone did not demonstrate any effect. As a result, targeting type I IFNs in conjunction with blocking the PD-L1-PD-1 signalling pathway can be a strategy for extending immune surveillance.