Characterization of a KDM5 Small Molecule Inhibitor with Antiviral Activity in Rodent Livers

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 rodent livers. Overall design: Male Wistar Han rats were dosed p.o. once daily for seven days with 10, 30, or 100 mg/kg of GS-5801 or water (vehicle control). 100 mg samples of liver tissue (left lateral lobe) were collected, snap frozen using liquid nitrogen, and stored at -80 °C for subsequent transcriptome analysis by RNAseq.