Osimertinib is a dual inhibitor of hepatocellular carcinoma and angiogenesis in an EGFR-independent manner, and synergizes with venetoclax.

Abstract

To investigate the effects of osimertinib on hepatocellular carcinoma (HCC) and angiogenesis, and its combinatory effects with venetoclax in HCC. Viability was assessed by flow cytometry of Annexin V in multiple HCC cell lines after drug treatment. In vitro angiogenesis assay was performed using primary human liver tumor associated endothelial cell (HLTEC). HCC-bearing model was generated by subcutaneous implantation of Hep3B cells to investigate the efficacy of osimertinib alone and its combination with venetoclax. Osimertinib significantly induced apoptosis in a panel of HCC cell lines regardless of EGFR expression level. It inhibited capillary network formation and induced apoptosis in HLTEC. Using HCC xenograft mouse model, we further showed that osimertinib at non-toxic dose inhibited tumor growth by ~ 50% and remarkably decreased blood vessel in tumor. Mechanism studies demonstrated that osimertinib acted on HCC cells in an EGFR-independent manner. It decreased level of VEGF and Mcl-1 in HCC cells via suppressed phosphorylation of eIF4E, thus leading to inhibition of eIF4E-mediated translation. Mcl-1 overexpression reversed pro-apoptotic effect of osimertinib, suggesting an important role of Mcl-1 in osimertinib's action in HCC cells. Of note, the combination of osimertinib and venetoclax achieved approximately complete HCC cell death and tumor growth in mice. We provide pre-clinical evidence that osimertinib is a promising candidate for the treatment of HCC via targeting tumor cells and angiogenesis. The combination of osimertinib and venetoclax is synergistic in inhibiting HCC.