CD274 and neoplasm: Lower tumor mutational burden (TMB), for example, in tumors of never smokers [12, 13], a different nature of PD-L1 expression (intrinsic, induced by oncogenic signaling rather than tumor-infiltrating lymphocytes) [14, 15] and features of the tumor microenvironment (TME) [16–19], possibly influenced by MAPK-signaling [20], have all been suggested as potential causes.