Novel Abs targeting the N‐terminus of fibroblast growth factor 19 inhibit hepatocellular carcinoma growth without bile‐acid‐related side‐effects

Hepatocellular carcinoma (HCC) is a common and particularly fatal form of cancer for which very few drugs are effective. The fibroblast growth factor 19 (FGF19) has been viewed as a driver of HCC development and a potential Ab target for developing novel HCC therapy. However, a previously developed anti‐FGF19 Ab disrupted FGF19’s normal regulatory function and caused severe bile‐acid‐related side‐effects despite of having potent antitumor effects in preclinical models. Here, we developed novel human Abs (G1A8 and HS29) that specifically target the N‐terminus of FGF19. Both Abs inhibited FGF19‐induced HCC cell proliferation in vitro and significantly suppressed HCC tumor growth in mouse models. Importantly, no bile‐acid‐related side effects were observed in preclinical cynomolgus monkeys. Fundamentally, our study demonstrates that it is possible to target FGF19 for anti‐HCC therapies without adversely affecting its normal bile acid regulatory function, and highlights the exciting promise of G1A8 or HS29 as potential therapy for HCC.