Characterization of a KDM5 Small Molecule Inhibitor with Antiviral Activity against Hepatitis B Virus

Chronic hepatitis B (CHB) is a global health care challenge and a major cause of liver disease. Existing therapies do not result in a functional cure in most individuals, necessitating new antiviral strategies against Hepatitis B virus (HBV). To identify additional therapeutic avenues, we performed a focused screen of epigenetic modifiers to identify inhibitors of HBV replication. From this work we identified small molecule inhibitors of the histone lysine demethylase 5 (KDM5) with antiviral activity against HBV. To enhance the cellular permeability and liver accumulation of the most potent KDM5 inhibitor identified (GS-080) a prodrug was developed (GS-5801) that resulted in improved bioavailability and liver exposure as well as increased accumulation of the H3K4me3:H3 ratio on chromatin. GS-5801 treatment of HBV-infected primary human hepatocytes inhibited HBV replication and antigen levels. Evaluation of GS 5801 antiviral activity in a humanized mouse model of HBV infection, however, did not result in antiviral efficacy, despite achieving pharmacodynamic levels of H3K4me3:H3 predicted to be efficacious. Together these data highlight discordance between the antiviral effects of GS 5801 observed in HBV-infected primary human hepatocytes. Overall design: HBV-infected primary human hepatocytes from three donors were treated with GS-5801 every three to four days for 13 days and total cellular mRNA was isolated and sequenced on days 1, 3, 10, and 13 after initiation of dosing