Assembly Biosciences, Inc. (ASMB) has announced encouraging news regarding its investigational drug ABI-5366, a potential game-changer in the fight against recurrent genital herpes. The company released interim pharmacokinetic (PK) and safety data from the Phase 1a portion of its ongoing Phase 1a/b study, revealing promising results.
ABI-5366, a long-acting herpes simplex virus (HSV) helicase-primase inhibitor, demonstrated a favorable safety profile in healthy participants. Notably, it showed extended PK properties, with exposure lasting up to 70 days. This extended profile is significant because it could potentially translate into a once-weekly or even once-monthly oral dosing regimen for patients.
The data also revealed that single doses of ABI-5366, at levels reached in Phase 1a, exceeded Assembly Bio’s target plasma concentrations for antiviral efficacy. This target was established based on PK modeling and is projected to deliver enhanced efficacy compared to currently approved therapies. The drug’s half-life, estimated at approximately 20 days across the evaluated doses, further supports the company’s vision of a convenient once-weekly oral dosing option, with potential for a once-monthly regimen in the future.
“With the exceptional oral half-life of ABI-5366, we look forward to exploring its potential for both once-weekly and once-monthly oral dosing,” said Jason Okazaki, CEO of Assembly Bio. The company has already initiated screening for the Phase 1b portion of the study, which will involve participants with recurrent genital herpes. Interim results from this phase are expected in the first half of 2025.
The safety profile of ABI-5366 is equally encouraging. Treatment-emergent adverse events (AEs) were mild to moderate in intensity and were deemed unrelated to the study treatment by the investigators. Importantly, there were no serious AEs observed in any dose arm.
These interim results have exceeded Assembly Bio’s expectations for the Phase 1a study and provide strong support for advancing ABI-5366 into Phase 1b. This next phase will evaluate multiple ascending doses of the drug in participants with recurrent genital herpes. The study will focus on weekly and monthly oral regimens over a 29-day treatment period, assessing not only safety and tolerability but also antiviral activity by measuring changes in viral parameters.
While the stock price of ASMB experienced a dip on Monday, the company remains optimistic about the potential of ABI-5366. The drug’s long-lasting effect, favorable safety profile, and potential for convenient dosing could significantly impact the treatment landscape for recurrent genital herpes. As the Phase 1b study progresses, we can expect further insights into the efficacy and potential of this promising drug candidate.
