Role of Core/Capsid Inhibitors in Functional Cure Strategies for Chronic Hepatitis B

Abstract

Purpose of Review: Functional cure of chronic hepatitis B (CHB), defined as sustained hepatitis B surface antigen (HBsAg) seroclearance, is associated with favourable clinical outcomes. Nonetheless, the functional cure is rarely achievable by current treatment modalities. Core/capsid inhibitors (core protein allosteric modulators, CpAMs) are a novel drug class that targets the hepatitis B core protein and may have a potential impact on the functional cure. This article reviews the preclinical and clinical results of CpAMs.

Recent Findings: CpAMs interfere with the hepatitis B virus (HBV) nucleocapsid assembly and also exert a secondary action on covalently closed circular DNA replenishment. CpAMs are able to sustainably suppress hepatitis B viral load and viral antigens in in vivo studies. In phase I/II clinical trials, CpAMs are well tolerated and are efficacious in suppressing viral replication. CpAMs also have synergistic antiviral effects when combined with nucleoside analogues or pegylated interferon. The clinical data has yet to demonstrate the capability of CpAMs in inducing HBsAg seroclearance, possibly due to the short follow-up period of current studies. There is emerging data showing initial viral antigen reduction with the continuation of CpAMs for more than 24 weeks.

Summary: CpAMs have shown promising preclinical and phase I/II clinical data. Data from long-term phase III trials and from combination therapies with other antiviral agents are keenly anticipated.