In the study made by Jiang et al., the tumor cytotoxic T-lymphocyte levels were evaluated via the average expression levels of CD8A, CD8B, GZMA, GZMB, and PRF1, and the results showed that the survival time of highly infiltrated cytotoxic T-lymphocyte patients receiving ICIs was prolonged distinctly. The gene discussed is PRF1; the disease is neoplasm.