Background: Hepatocellular carcinoma (HCC) is one of the most lethal malignancies and the identification of new effective therapies for HCC is urgently needed. We have previously identified EpCAM, one of the hepatic stem/progenitor markers, as a prognostic predictor of patients who received curative hepatectomy for HCC. In this preclinical study, the effects of VB4-845, an immunotoxin targeting EpCAM, were evaluated in HCC.
Methods: In vitro effects of VB4-845 on human HCC cells, the cytotoxic activity, sphere-forming ability, and expression of hepatic stem/progenitor markers were analyzed. In vivo effects of VB4-845 were evaluated using subcutaneous and orthotopic liver xenograft models.
Results: In all HCC cell lines expressing EpCAM, VB4-845 showed potent cytotoxicity and was significantly effective in combination with 5-FU (p < 0.05). Although 5-FU did not affect the sphere-forming ability and increased the populations expressing other stem/progenitor markers CD133 and CD13 (p < 0.05), VB4-845 strongly suppressed the sphere-formation and decreased the population expressing CD133 and CD13 (p < 0.0005, <0.01, respectively). In subcutaneous xenograft models, the combination of VB4-845 plus 5-FU showed significant regression of tumors compared with the control (p = 0.016). Moreover, in orthotopic liver xenograft models, the combination therapy dramatically decreased the tumor volume compared with the control (p = 0.0011).
Conclusions: Our preclinical investigation suggests that EpCAM-targeted therapy may offer a promising and novel approach for the treatment of HCC with a poorer prognosis.