The most widely explored biomarkers for predicting responders to PD-1 inhibitors are the expression level of programmed death-ligand 1 (PD-L1) and tumor mutational burden (TMB), which track to overall clinical response rates of 27% and 58%, respectively (Ferris et al., 2018, Goodman et al., 2017). This evidence concerns the gene PDCD1 and neoplasm.