Assembly Bio reports positive interim data for genital herpes drug

Published 10/10/2025, 13:06
Assembly Bio reports positive interim data for genital herpes drug

ATHENS - Assembly Biosciences, Inc. (NASDAQ:ASMB) presented interim Phase 1b clinical data for its long-acting herpes simplex virus (HSV) helicase-primase inhibitor candidate ABI-5366 at the 38th Congress of the International Union Against Sexually Transmitted Infections in Athens, Greece. The $417 million market cap biotech company has seen its stock surge over 217% in the past six months, according to InvestingPro data, reflecting growing investor interest in its pipeline developments.

The data showed that a 350 mg weekly oral dose of ABI-5366 demonstrated statistically significant reductions compared to placebo in HSV type 2 shedding rate (94% decrease), high viral load shedding rate (98% decrease), and genital lesion rate (94% decrease) in participants with recurrent genital herpes.

The drug was well tolerated at both doses evaluated in the study, which included two cohorts. The first cohort received a 150 mg loading dose followed by weekly doses of 30 mg, while the second cohort received weekly doses of 350 mg.

"These results highlight the potential to reduce viral shedding rates and the burden of recurrent genital lesions with a weekly oral dose of ABI-5366," said Anuj Gaggar, MD, PhD, chief medical officer of Assembly Bio, in a press release statement.

The company is currently evaluating a monthly oral dosing regimen of ABI-5366 in the ongoing Phase 1b study. Additionally, a separate Phase 1b study is assessing weekly dosing of ABI-1179, another long-acting HSV helicase-primase inhibitor candidate. Assembly Bio expects to share interim data from both studies later this fall.

Assembly Bio plans to initiate Phase 2 clinical studies of ABI-5366 in mid-2026. Under a collaboration agreement with Gilead Sciences, Inc., Gilead has the right to opt in to an exclusive license for further development and commercialization of the helicase-primase inhibitor program after reviewing data from the completed Phase 1b studies. Analysts tracked by InvestingPro maintain a strong buy consensus, with price targets ranging from $29 to $50, suggesting significant upside potential despite the company’s current unprofitable status.

No new drugs have been approved in the United States or Europe to treat genital herpes for more than 25 years, according to the company. While the company currently operates with negative margins and holds more cash than debt on its balance sheet, InvestingPro subscribers can access 10+ additional investment insights about Assembly Bio’s financial health and growth prospects.

In other recent news, Assembly Biosciences announced positive interim results from a Phase 1b study of its investigational herpes simplex virus treatment, ABI-5366. The study showed a 94% reduction in HSV-2 shedding rate, surpassing the company’s target of 80-85%. This promising data led Guggenheim to raise its price target for Assembly Biosciences to $39, maintaining a Buy rating. Additionally, H.C. Wainwright assumed coverage with a Buy rating and a $50 price target, emphasizing the potential of Assembly’s antiviral pipeline.

To support its research efforts, Assembly Biosciences priced a $130 million offering of approximately 6.6 million shares and warrants. The offering, priced at $19.60 per share, aims to fund the company’s viral disease therapeutic development programs. Meanwhile, JMP analyst Roy Buchanan initiated coverage with a Market Outperform rating, citing the team’s successful track record in drug development. These developments underscore the growing interest in Assembly Biosciences’ innovative treatments and strategic collaborations.

This article was generated with the support of AI and reviewed by an editor. For more information see our T&C.

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