Abstract
The development of immune checkpoint inhibitors represented by PD-1 and PD-L1 has provided new hope for the treatment of advanced cancer patients. However, there are no effective predictive biomarkers, which have caused many limitations to the clinical application of immune checkpoint inhibitors. This paper combines recent domestic and international research as well as clinical trials to discuss the current status and progress of PD-L1 expression as a biomarker for tumor immunotherapy and also to discuss whether tumor mutation burden, tumor-infiltrating lymphocytes, tumor cell gene expression profiling, or peripheral blood markers would be a potential predictive biomarker for novel tumor immunotherapy. So, a brief review on this hot topic of predictive biomarkers for tumor immunotherapy is conducted.