Although various studies have shown that tumor mutational burden,14 microbiota,15 and tumor-infiltrating lymphocytes16 correlate with the efficacy of diverse anti-PD-1/PD-L1 drugs in non–small cell lung cancer and melanoma, the correlation between those biomarkers and the efficacy of PD-1/PD-L1 blockade in GI tract cancer is uncertain. The gene discussed is CD274; the disease is lung cancer.