CD274 and metastatic melanoma: Over the past decade, medical authorities have approved the use of antibodies against the immune checkpoint (ICP) PD1 or its ligand PDL1 as a treatment for metastatic melanoma (MM), based on their strong therapeutic efficacy and ability to extend long-term survival in some patients.1,2 Anti-PD1/L1 therapy aims to block the interaction between PD1 on tumor-reactive T cells and PD1 ligands (PDL1 and PDL2) expressed on various cell types, including tumor cells and leukocytes (for review3).