CD274 and neoplasm: However, due to the cold tumor microenvironment with two mutations per DNA megabase (17), 23% ± 13% of CD8+ lymphocytes (18), 6.6% of programmed death-ligand 1 (PD-L1) (19), PD-1 inhibitors monotherapy failed to show satisfactory tumor response and durable antitumor control in most STS.