PDCD1 and neoplasm: Although tumor PD-L1 expression is not a perfect biomarker with regard to its ability to predict the efficacy of immunotherapy, PD-L1 detection by immunohistochemistry (IHC) is currently the most convenient and economical method, and it has commonly been used to identify patients who may be more likely to benefit from immunotherapy with PD-1/PD-L1 inhibitors.