One explanation for our findings is that the population of countries not studied as extensively in the PACIFIC trial may have far lower median percentages of PD-L1–positive tumors and/or higher percentages of EGFR-mutant NSCLC, such as in Brazil,40 or ALK-rearranged NSCLC, such as in Singapore.41 This evidence concerns the gene CD274 and non-small cell lung carcinoma.