Assembly Biosciences, Inc. announced the selection of development candidate ABI-5366 (5366) to progress to IND-enabling studies for its long-acting herpes simplex virus type 2 (HSV-2) helicase inhibitor program. 5366 is the first development candidate from Assembly Bio's discovery pipeline nominated for advancement to clinical development since the company announced its expanded research focus outside of hepatitis B last year. Assembly Bio's HSV-2 program targets the viral helicase-primase, an essential viral enzyme complex and a clinically validated target.

Helicase inhibition has demonstrated greater reductions in HSV-2 shedding, lesions and pain compared to approved suppressive nucleoside analog regimens in previous clinical studies. 5366, a small molecule helicase inhibitor with nanomolar potency in vitro, is designed for long-acting administration and has shown favorable pharmacokinetics (PK) for a long-acting therapeutic, including the key property of exceptionally low clearance, in preclinical studies. 5366's preclinical profile shows the potential for at least monthly dosing, and Assembly Bio will continue to evaluate longer dosing intervals as development and formulation progress.

High-recurrence genital herpes associated with HSV-2 infection is characterized by frequent recurrences of lesions (six or more per year) and is estimated to affect up to 40% of HSV-2 genital herpes patients following their first outbreak. Approved suppressive therapy regimens consist of oral daily dosing of nucleoside analogs, a class first approved for genital herpes almost three decades ago, with no new drug approvals in the last 20 years. These suppressive regimens have been shown to reduce the recurrence of genital herpes among patients with high HSV-2 recurrence, but eliminate recurrences for only a minority of these patients.