CD274 and melanoma: Programmed death‐ligand 1 (PD‐L1), a membrane bound ligand on many cancer cells, can bind programmed death‐1 (PD‐1) receptor on T cells to suppresses antigen‐derived activation of T cells and elicit the immune checkpoint response.122, 123 It has been found that PD‐L1 is also located on the surface of TEXs from plasma samples of patients with a variety of cancers.124 Two recent studies found exosomal PD‐L1 could play critical immunosuppressive roles in melanoma and prostate cancer76, 125 (Figure 3a).