PDCD1 and melanoma: To determine, in isolated cell models, the ability of circulating EVs to modify the behaviour of immune cells thus elucidating the mechanisms responsible for the clinical response, we initially investigated their ability to impact on the growth of melanoma LND-1 cells (2D model) and MM patient-derived organoids (3D-PDOs) from a RES, when exposed to anti-PD1 in presence of PBMCs isolated from the same patient and activated as described in Methods section.