Plasma and tumoral glypican‐3 levels are correlated in patients with hepatitis C virus‐related hepatocellular carcinoma

Glypican‐3 (GPC3) is a cancer antigen expressed in approximately 80% of hepatocellular carcinomas (HCC) and is secreted into the blood. To confirm the effectiveness of GPC3 as a biomarker in HCC, we analyzed the relationship between GPC3 expression levels in cancer cells and in blood in 56 patients with HCC. Preoperative plasma GPC3 levels were determined with an immunoassay, and expression of GPC3 in resected tumors was analyzed by immunohistochemical staining. Median plasma GPC3 level in all HCC cases was 4.6 pg/mL, and tended to be higher in patients with hepatitis C virus (HCV)‐related HCC (HCV group) (9.9 pg/mL) than in patients with hepatitis B virus (HBV)‐related HCC (HBV group) (2.6 pg/mL) or in those without virus infection (None group) (3.0 pg/mL), suggesting that the virus type most likely influences GPC3 secretion. Median percentage of GPC3+ cells in tumors was also higher in the HCV (26.2%) and HBV (11.1%) groups than in the None group (4.2%). In the HCV group, there was a positive correlation between the two parameters (r = 0.66, P  10% GPC3+ cells in a tumor if the cut‐off value was 6.8 pg/mL (sensitivity 80%, specificity 100%; area under the curve 0.875, 95% confidence interval 0.726‐1) in the HCV group. Plasma concentration of GPC3 could be a predictive marker of tumoral GPC3 expression in patients with HCV‐related HCC, suggesting a useful biomarker for immunotherapies targeting GPC3, although larger‐scale validations are needed.