PDCD1 and melanoma: In our approach, PD-L1+ EVs assayed in plasma from a large cohort of MM patients by FCM instead of the ELISA kit did not confirm Chen’s data, however the comparative analysis of these EV levels in responders and non-responders, categorised according to their cells of origin, pointed out that only PD-L1+ EVs from melanoma and CD8+ T cells were promising biomarkers of resistance to anti-PD1.