Assembly Biosciences Announces Positive Phase 1a Results for ABI-1179 in Recurrent Genital Herpes

Assembly Biosciences, a biotechnology firm focused on innovative treatments for severe viral diseases, recently shared encouraging interim outcomes from its Phase 1a study of ABI-1179. This investigational drug, targeting recurrent genital herpes, is a herpes simplex virus (HSV) helicase-primase inhibitor. The company, based in South San Francisco, has seen promising results regarding the safety and pharmacokinetic profile of ABI-1179, suggesting it could be administered orally once a week.

The trial demonstrated that ABI-1179 has a half-life of about four days and exhibits high exposure across various doses, meeting Assembly Bio’s objectives for a weekly oral dosing regimen. Reportedly, even the lowest evaluated dose of 50 mg achieved desired plasma concentrations for antiviral activity. This finding indicates the potential for improved efficacy over existing therapies. The drug was deemed safe and well-tolerated, with any adverse events being mild and not linked to the treatment. Importantly, no serious adverse effects were reported, although a grade 2 elevation in alanine transaminase was noted at the highest dose of 300 mg.

Given these Phase 1a results, Assembly Bio plans to advance ABI-1179 to Phase 1b of the ongoing study, targeting participants with recurrent genital herpes. This Phase 1b trial will be conducted alongside the Phase 1b study of ABI-5366, another helicase-primase inhibitor candidate. Both trials will employ similar criteria and outcome measures, enabling concurrent execution and a joint interim data report anticipated in fall 2025.

Assembly Bio’s CEO, Jason Okazaki, acknowledged the significant impact of recurrent genital herpes on millions worldwide. He emphasized the lack of new therapeutic advancements for this condition over recent decades. Okazaki expressed optimism for ABI-1179 and ABI-5366, both of which surpassed expectations in the Phase 1a trials. These drugs have the potential to enhance treatment outcomes for those affected by recurrent genital herpes.

ABI-1179 originated from a collaboration with Gilead Sciences, Inc., highlighting the strategic partnership between the two companies. Neither ABI-1179 nor ABI-5366 has received global approval, and their safety and effectiveness remain under evaluation.

The ongoing study, designated ABI-1179-101, is a randomized, blinded, placebo-controlled Phase 1a/b trial. Part A involves assessing the safety, tolerability, and pharmacokinetics of ABI-1179 with single ascending doses in healthy individuals. So far, dosing has been completed for three cohorts, examining 50 mg, 100 mg, and 300 mg doses. Each cohort follows a 6:2 randomization between ABI-1179 and a placebo. Safety data from these cohorts have been compiled, highlighting ABI-1179’s ability to sustain antiviral plasma concentrations with a once-weekly low oral dose.

The upcoming Phase 1b segment will explore the effects of weekly oral administration of ABI-1179 over 29 days in participants with HSV-2-associated recurrent genital herpes. This phase will assess both safety and antiviral activity, including changes in viral shedding and lesion recurrence.

Recurrent genital herpes, primarily caused by HSV-2, affects millions worldwide, leading to painful lesions and severe psychological impacts. Although current treatments exist, they are only partially effective, underscoring the need for innovative solutions. Helicase-primase inhibitors, like ABI-1179, target a crucial viral enzyme complex, offering a promising alternative to existing therapies.

Assembly Biosciences is committed to developing groundbreaking therapeutics for viral diseases, striving to improve patient outcomes globally. With a team of experts in virologic drug development, Assembly Bio continues to focus on addressing the challenges posed by herpesvirus and other viral infections.