PDCD1 and melanoma: We have recently demonstrated that circulating PD1+ EVs are driver of innate resistance to anti-PD1, by sequestering the PD-1 blocking antibodies, and highlighted that the determination of the percentage of three circulating EV subpopulations (PD1+ EVs from T cells and B cells and PD-L1+ EVs from melanoma) by liquid biopsy is a promising tool to select MM patients for treatment with Nivolumab or Pembrolizumab [7, 8].