H3B-6527 is a highly selective covalent FGFR4 inhibitor with at least 250-fold selectivity over FGFR1-3. H3B-6527 inhibits FGFR4 signaling, proliferation, and leads to apoptosis in Hepatocellular carcinoma (HCC) cell line. Treatment on Hep3B cells leads to robust activation of caspase-3/7, an apoptotic marker, in a concentration-dependent manner, indicating FGFR4 inhibition by H3B-6527 leads to cell death in HCC cell lines. In the Hep3B human HCC xenograft mouse model, H3B-6527 shows dose-proportional plasma exposures and greater than dose-proportional tumor exposures within the dose range evaluated (30, 100, and 300 mg/kg). Oral treatment of H3B-6527, twice daily, inhibits xenograft growth in a dose-dependent manner in nude mice, with the 300 or 100 mg/kg twice daily, significantly inhibiting tumor growth in both Hep3B subcutaneous and orthotopic xenograft model and causing tumor regressions in the subcutaneous xenograft model.