CD274 and neoplasm: Of note, this checkpoint blockade-mediated liberation of anti-tumor T cell responses is most effective in tumors that have a high mutational burden (39, 40) [i.e., that result in greater presentation of neo-antigens, especially those with mismatch-repair defects (41, 42)], and in those that upregulate the checkpoint ligands such as PD-L1 (43, 44).