PDCD1 and melanoma: A previous study among 355 patients with advanced melanoma resistant to PD-1 or PD-L1 monotherapy demonstrated that ipi plus anti-PD-1 as a salvage therapy showed better clinical efficacy than ipi alone, with a higher ORR (31.1 vs. 13.0%, p < 0.001) and longer median PFS (3.0 vs. 2.6 months, p = 0.002) and OS (20.4 vs. 8.8 months, p < 0.001) (31).