- Assembly Biosciences announced on **October 10, 2025**, that interim Phase 1b clinical data for its long-acting herpes simplex virus (HSV) helicase-primase inhibitor candidate **ABI-5366** were presented at the 38th Congress of the International Union Against Sexually Transmitted Infections (IUSTI)- Europe.  **[1426800_8777482ea4524bdda07baa648a1bce7d_0]** 
- In the **350 mg weekly dosing cohort**, ABI-5366 demonstrated **statistically significant reductions** compared to placebo, including a **94%** decrease in HSV type 2 (HSV-2) shedding rate, a **98%** decrease in high viral load shedding rate, and a **94%** decrease in genital lesion rate.  **[1426800_8777482ea4524bdda07baa648a1bce7d_0]** 
- **ABI-5366 was observed to be well tolerated** at both evaluated doses, and its pharmacokinetic profile supports weekly and potentially monthly dosing.  **[1426800_8777482ea4524bdda07baa648a1bce7d_0]** 
- Assembly Bio expects to share further interim data for a **monthly dosing regimen of ABI-5366** and for **ABI-1179** (another HSV helicase-primase inhibitor candidate) later this fall, with **Phase 2 clinical studies of ABI-5366 anticipated to begin in mid-2026**.  **[1426800_8777482ea4524bdda07baa648a1bce7d_1]** 
- Under a collaboration agreement, **Gilead Sciences, Inc.** has the right to opt in to an exclusive license for the helicase-primase inhibitor program after reviewing the option data package following completion of the Phase 1b studies.  **[1426800_8777482ea4524bdda07baa648a1bce7d_1]**

ASSEMBLY BIOSCIENCES (ASMB)