At present, with the further study of biomarkers, some studies also have found that Tumor Protein p53 (TP53) or Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene mutations can increase the expression of PD-L1 and CD8+ T-cell infiltration; when both mutations are present, the expression of PD-L1 will be more significant, the tumor mutation load is often high, and the clinical benefits of pembrolizumab therapy are often better. This evidence concerns the gene CD8A and neoplasm.