CD274 and mesothelioma: For example, the KEYNOTE-028 trial reported objective response rates (ORRs) of ~20% in PD-L1-positive mesothelioma patients treated with the PD-1 inhibitor pembrolizumab (PEMBRO) [12], whereas the KEYNOTE-158 study found ORRs of ~8–20% in unselected, previously treated populations [13].