CD274 and cancer: Indeed, one of the major determinants of resistance to ICIs in patients with cancer is scarce infiltration of the tumor microenvironment (TME) at baseline by cytotoxic T lymphocytes (CTLs) [13], which often correlates with (1) a reduced tumor mutational burden and hence a low neoantigen load [14] and (2) limited expression of the coinhibitory ligand CD274 (best known as PD-L1) [15].