Cytolytic Activity (CYT) Score Is a Prognostic Biomarker Reflecting Host Immune Status in Hepatocellular Carcinoma (HCC)

Background/Aim: The cytolytic activity (CYT) score is a new index of cancer immunity calculated from the mRNA expression levels of GZMA and PRF1. We assessed the clinical significance of the CYT score in HCC. Materials and Methods: The calculated CYT scores of peripheral blood cells (GSE24759), cell lines (CCLE) and HCC tissues (TCGA, GSE14520 and Kyushu cohorts) were assessed. Then, immunohistochemical analysis (IHC) of GZMA and PRFI was performed. Results: The CYT scores of HCC tissues were lower than those of non-cancerous tissues. The 5-year recurrence-free survival of patients with low CYT scores was significantly shorter than that of patients with high CYT scores. Multivariate analysis indicated that the CYT score was an independent prognostic factor for RFS in TCGA and GSE14520 cohorts. Conclusion: CYT score could be a useful prognostic biomarker in HCC, possibly through reflecting the host immune status.