AB-423 (Capsid Inhibitor)

HBV core protein, or capsid, is required for viral replication and core protein may have additional roles in cccDNA function. Current nucleot(s)side analog therapy significantly reduces HBV DNA levels in the serum but HBV replication continues in the liver, thereby enabling HBV infection to persist. Effective therapy for patients requires new agents which will effectively block viral replication.


We are developing capsid inhibitors as oral therapeutics for the treatment of chronic HBV infection. By inhibiting assembly of the viral capsid, the ability of hepatitis B virus to replicate is impaired, resulting in reduced cccDNA.


Our first-generation capsid inhibitor, AB-423, was evaluated in a Phase I Single Ascending Dose (SAD) and Multiple Ascending Dose (MAD) trial in healthy volunteers, which was generally well-tolerated with no serious adverse events following single doses up to 800mg and multiple doses up to 400mg twice daily. AB-423’s favorable safety and pharmacokinetics (PK) profile following single and multiple doses in healthy volunteers supports further evaluation in our multiple-dose administration study of AB-423 in patients with chronic HBV. Following initial studies of AB-423 in HBV patients, we will consider inclusion in a combination study with our other proprietary HBV assets, nucleot(s)ide analog, and interferon therapies.


AB-506 is a next-generation capsid inhibitor currently undergoing Investigational New Drug (IND)-enabling studies. In preclinical studies, this new capsid inhibitor has demonstrated favorable PK and potency profiles. Pending successful IND-enabling studies, this product candidate could be the subject of an Investigation New Drug (or equivalent) filing.