Assembly Biosciences Reports Positive Interim Results for HSV-2 Treatment Studies

Assembly Biosciences announced interim results from two Phase 1b studies of its investigational long-acting herpes simplex virus helicase-primase inhibitors in participants seropositive for HSV type 2 with recurrent genital herpes. These interim results include the first reported Phase 1b data for ABI-1179, evaluating weekly oral dosing. For ABI-5366, the reported data is for a monthly oral dosing regimen, following the positive interim results for weekly oral dosing reported earlier this year. cohort. This reduction exceeds Assembly Bio's target for the study of an 80%-85% reduction in HSV-2 shedding rate. Further, data revealed a 91% reduction in virologically confirmed genital lesion rate compared to placebo with the 50 mg weekly dose. There was also a greater than 99% reduction in the number of samples with high viral load, a potential surrogate for HSV-2 transmission and a secondary endpoint. ABI-1179 was observed to be well-tolerated at oral doses up to 50 mg weekly and the observed pharmacokinetic profile continues to support once-weekly oral dosing regimens. In the ABI-5366 monthly dose cohort, potent antiviral activity was observed, with a 76% reduction in HSV-2 shedding rate compared to placebo over the 29-day evaluation period. The majority of positive swabs were collected in the last two weeks of the evaluation period when drug levels were declining. An 88% reduction in virologically confirmed genital lesion rate, along with an 81% reduction in the number of samples with high viral load compared to placebo, was observed. As previously reported for the 350 mg weekly dose cohort, a 94% reduction in HSV-2 shedding rate and a 97% reduction in virologically confirmed genital lesion rate compared to placebo was observed. ABI-5366 continues to be well-tolerated across all evaluated oral dosing regimens up to 350 mg weekly, and the PK profile supports both once-weekly and potentially once-monthly oral dosing regimens. Under the collaboration agreement between Assembly Bio and Gilead (GILD), Gilead has the right to opt in to an exclusive license for further development and commercialization of the helicase-primase inhibitor program, with the first option timepoint extending through the review of an option data package to be delivered by Assembly Bio following the end of the Phase 1b studies. ABI-1179 was contributed by Gilead under the collaboration between Assembly Bio and Gilead. ABI-5366 and ABI-1179 are investigational product candidates that have not been approved anywhere globally, and their safety and efficacy have not been established.