Impact of Immune Response on Outcomes in Hepatocellular Carcinoma: Association With Vascular Formation.

Abstract

We investigated the prognostic value of programmed death ligand 1 (PD-L1) expression, tumor-infiltrating CD8-positive T-cell status, and their combination in hepatocellular carcinoma (HCC). Their association with PD-L1 expression and vascular formation was further explored. Using a database of 387 patients who underwent hepatic resection for HCC, immunohistochemical staining of PD-L1, CD8, and CD34 was performed. Additionally, we undertook an enzyme-linked immunosorbent assay for soluble PD-L1. Compared with patients with HCC and PD-L1-negative expression (n=311), patients with HCC and PD-L1-positive expression (n=76) showed significantly worse overall survival (OS; multivariate hazard ratio, 2.502; 95% confidence interval [CI], 1.716-3.649; P<0.0001). The presence of tumor-infiltrating CD8-positive T cells was significantly correlated with longer OS (multivariate hazard ratio, 0.383; 95% CI, 0.274-0.537; P<0.0001). Stratification based on PD-L1 expression in cancer cells and tumor-infiltrating CD8-positive T-cell status was also significantly associated with OS (log-rank, P<0.0001). HCC with PD-L1-positive expression was significantly correlated with positivity for vessels that encapsulated tumor clusters. Serum PD-L1 levels were significantly higher in the group of patients who had PD-L1-positive expression than in the group of patients who had PD-L1-negative expression (P=0.0158). PD-L1 expression in cancer cells was associated with a poor clinical outcome and vascular formation in patients with HCC. Additionally, the combination of PD-L1 expression with tumor-infiltrating CD8-positive T-cell status enabled further classification of patients based on their clinical outcome. Thus, PD-L1 expression in cancer cells and tumor-infiltrating CD8-positive T-cell status might serve as predictive tissue biomarkers.