Assembly Biosciences (ASMB) Study Result summary

Study design and objectives

• Phase 1b studies of ABI-1179 and ABI-5366 were randomized, double-blind, placebo-controlled trials in HSV-2 seropositive participants with recurrent genital herpes, using weekly and monthly dosing regimens.

• Each cohort included 20 patients on active drug and 5 on placebo, with balanced baseline demographics; most participants were white, aged 35–44, with active disease and prior suppressive therapy.

• Key endpoints included HSV-2 viral shedding, high viral load shedding, and virologically confirmed genital lesions.

• Dosing regimens included weekly and monthly oral administration, with ongoing evaluation of lower doses and PK/PD modeling for dose selection.

• Pharmacokinetic profiles support once-weekly and potentially once-monthly dosing for both candidates.

Efficacy results

• ABI-1179 (50 mg weekly) achieved a 98% reduction in HSV-2 shedding, >99% reduction in high viral load shedding, and 91% reduction in virologically confirmed lesions versus placebo.

• ABI-1179 (20 mg weekly) showed 92% reduction in HSV-2 shedding, 96% reduction in high viral load shedding, and 82% reduction in lesion rate.

• ABI-5366 (350 mg weekly) achieved a 94% reduction in HSV-2 shedding and 97% reduction in virologically confirmed lesions; monthly dosing showed up to 76% reduction in shedding and 88% reduction in lesions.

• Both candidates demonstrated >98% reduction in high viral load shedding, a surrogate for HSV-2 transmission, and efficacy exceeded historical results from standard therapies.

• Statistically significant reductions in all key virologic and clinical endpoints were observed for both candidates compared to placebo.

Safety and tolerability

• Both ABI-1179 and ABI-5366 were well tolerated at all tested doses, with most adverse events being grade 1 or 2 and no serious adverse events or deaths reported.

• Grade 3 adverse events were rare and not considered treatment-related; laboratory abnormalities were mostly mild and similar between active and placebo groups.

• No safety signals identified in human or animal studies, including chronic toxicology.