Farnesoid X receptor agonist for the treatment of chronic hepatitis B: A safety study

The nuclear farnesoid X receptor (FXR) regulates bile acid homeostasis and is a drug target for metabolic liver diseases. FXR also plays an important role in hepatitis B virus (HBV) DNA transcription. In vitro and in mice, FXR agonist treatment leads to inhibition of viral replication and a decline in viral proteins, pregenomic RNA (pgRNA) and HBV DNA levels. We aimed to translate this to a clinical use by primarily evaluating the safety and secondary the anti‐viral effect of Vonafexor, a FXR agonist, in chronic hepatitis B (CHB) patients. In total, 73 CHB patients were enrolled in a two‐part Phase Ib double‐blind, placebo‐controlled trial. Patients were randomized to receive oral Vonafexor (100, 200 and 400 mg once daily, or 200 mg twice daily), placebo, or entecavir (Part A, n = 48) or to receive Vonafexor (300 mg once daily or 150 mg twice daily), or placebo, combined with pegylated‐interferon‐α2a (Part B, n = 25) for 29 days. Patients were followed up for 35 days. Enrolled CHB patients were mostly HBeAg‐negative. Vonafexor was overall well tolerated and safe. The most frequent adverse events were moderate gastrointestinal events. Pruritus was more frequent with twice‐daily compared with once‐daily regimens (56%–67% vs. 16%, respectively, p < 0.05). Vonafexor monotherapy of 400 mg once daily decreased HBsAg concentrations (–0.1 log(10) IU/mL, p < 0.05), and Vonafexor/pegylated‐IFN‐α2a combination therapy decreased HBcrAg and pgRNA. In conclusion, Vonafexor was safe with a decline in HBV markers observed in CHB patients suggesting a potential anti‐viral effect the therapeutic potential of which has to be evaluated in larger trials.