PDCD1 and melanoma: Thus, the Cox analyses on PFS revealed that the most significant variables as negative factors, both in term of hazard ratios and p-values, are high content of PD1+ EVs from CD8+ T cells and of PD-L1+ EVs from melanoma (4th quartile HR (95% CI) equal to 22.35 (1.18-422.53) and 41.8 (3.28-532.71), respectively).