Press Releases April 8, 2026 08:00 PM

Assembly Biosciences Highlights Presentations on Positive Phase 1b Data for ABI-5366 and ABI-1179 in Recurrent Genital Herpes at ESCMID Global 2026

Assembly Biosciences announces positive Phase 1b clinical data presentations for HSV therapeutics ABI-5366 and ABI-1179 at ESCMID Global 2026

By Caleb Monroe ASMB
Assembly Biosciences Highlights Presentations on Positive Phase 1b Data for ABI-5366 and ABI-1179 in Recurrent Genital Herpes at ESCMID Global 2026
ASMB

Assembly Biosciences reported encouraging Phase 1b data for its investigational long-acting herpes simplex virus (HSV) helicase-primase inhibitors ABI-5366 and ABI-1179. The data, highlighting safety, tolerability, and potential efficacy in treating recurrent genital herpes, will be presented at the ESCMID 2026 conference. These drug candidates are licensed to Gilead Sciences for further development and commercialization.

Key Points

  • Positive Phase 1b clinical data for ABI-5366 supports its potential as an oral, long-acting therapeutic for recurrent genital herpes.
  • ABI-1179 Phase 1b data selected as a late-breaker poster, highlighting its promise as a long-acting HSV therapeutic.
  • The data presentations at a major infectious diseases conference enhance visibility and validation of Assembly Bio's antiviral pipeline.
  • Impacted sectors include biotechnology, pharmaceuticals, and infectious disease therapeutics markets.

– Additional Phase 1b data for ABI-5366, including results from monthly dosing cohort, selected for oral presentation –

– Phase 1b data from ABI-1179 accepted for late-breaker poster presentation –

SOUTH SAN FRANCISCO, Calif., April 09, 2026 (GLOBE NEWSWIRE) -- Assembly Biosciences, Inc. (Nasdaq: ASMB), a biotechnology company developing innovative therapeutics targeting serious viral diseases, today announced Phase 1b clinical data for ABI-5366 and ABI-1179, herpes simplex virus (HSV) helicase-primase inhibitor candidates, will be featured in multiple presentations, including one late-breaker, at the 2026 Congress of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) taking place April 17-21, 2026, in Munich, Germany.

“The selection of ABI-5366 for oral presentation at ESCMID underscores the strength and clinical relevance of the data generated to date, including additional results from the monthly dosing cohort,” said Anuj Gaggar, MD, PhD, chief medical officer of Assembly Bio. “We are also pleased to see the first scientific presentation of Phase 1b data for ABI-1179 recognized as a late-breaker presentation, which highlight its potential as a long-acting therapeutic option for patients with recurrent genital herpes.”

Details of the presentations are as follows:

ABI-5366:

  • Oral Presentation: ABI-5366-101: a phase 1b study of a novel, oral, long-acting, investigational HSV helicase-primase inhibitor in recurrent genital herpes
    Presenter: Mark Bloch, MBBS, Momentum Clinical Research and Kirby Institute, University of New South Wales
    Session Date and Time: April 20, 2026, at 5:30 PM CEST
  • Poster Presentation: Virologic analyses following treatment with ABI-5366, a novel, oral, long-acting HSV helicase-primase inhibitor in participants seropositive for HSV-2 with recurrent genital herpes
    Presenter: Kathryn Kitrinos, PhD, Assembly Bio
    Session Date and Time: April 18, 2026, at 12:00 PM CEST
  • Poster Presentation: The safety and tolerability of ABI-5366, a novel, oral, long-acting HSV helicase-primase inhibitor in participants with recurrent genital herpes
    Presenter: Cory Sellwood, MBBS, New Zealand Clinical Research
    Session Date and Time: April 18, 2026, at 12:00 PM CEST

ABI-1179:

  • Poster Presentation (Late-Breaker): The safety and efficacy of ABI-1179, a novel, oral, long-acting HSV helicase-primase inhibitor for recurrent genital herpes: interim results from a phase 1b study
    Presenter: Mark Bloch, MBBS, Momentum Clinical Research and Kirby Institute, University of New South Wales
    Session Date and Time: April 21, 2026, at 12:00 PM CEST

Assembly Bio intends to make the posters available on the “Events & Presentations” page in the “Investors” section and on the “Publications” page in the “Pipeline” section of its website at www.assemblybio.com.

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. They are exclusively licensed to Gilead Sciences, Inc. (Gilead) under the collaboration between Assembly Bio and Gilead, and Gilead has the sole right and responsibility for further clinical development and commercialization of these programs.

About Assembly Biosciences
Assembly Biosciences is a biotechnology company dedicated to the development of innovative small-molecule therapeutics designed to change the path of serious viral diseases and improve the lives of patients worldwide. Led by an accomplished team of leaders in virologic drug development, Assembly Bio is committed to improving outcomes for patients struggling with the serious, chronic impacts of herpesvirus, hepatitis B virus (HBV) and hepatitis delta virus (HDV) infections. For more information, visit assemblybio.com.

Forward-Looking Statements
The information in this press release contains forward-looking statements that are subject to certain risks and uncertainties that could cause actual results to materially differ. These risks and uncertainties include: Assembly Bio’s ability to realize the potential benefits of its collaboration with Gilead, including all financial aspects of the collaboration and equity investments; Assembly Bio’s ability to initiate and complete clinical studies involving its therapeutic product candidates, including studies contemplated by Assembly Bio’s collaboration with Gilead, in the currently anticipated timeframes or at all; safety and efficacy data from clinical or nonclinical studies may not warrant further development of Assembly Bio’s product candidates; clinical and nonclinical data may not differentiate Assembly Bio’s product candidates from other companies’ candidates; Assembly Bio’s ability to maintain financial resources and secure additional funding necessary to continue its research activities, clinical studies, and other business operations; potential effects of changes in government regulation; results of nonclinical studies may not be representative of disease behavior in a clinical setting and may not be predictive of the outcomes of clinical studies; and other risks identified from time to time in Assembly Bio’s reports filed with the U.S. Securities and Exchange Commission (the SEC). You are urged to consider statements that include the words may, will, would, could, should, might, believes, hopes, estimates, projects, potential, expects, plans, anticipates, intends, continues, forecast, designed, goal or the negative of those words or other comparable words to be uncertain and forward-looking. Assembly Bio intends such forward-looking statements to be covered by the safe harbor provisions contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. More information about Assembly Bio’s risks and uncertainties are more fully detailed under the heading “Risk Factors” in Assembly Bio’s filings with the SEC, including its most recent Annual Report on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K. Except as required by law, Assembly Bio assumes no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

Contacts:

Investors:
Patrick Till
Meru Advisors
(484) 788-8560
[email protected]

Media:
Sam Brown LLC
Alyssa Kuciunas
(331) 481-3751
[email protected]


Risks

  • The investigational products ABI-5366 and ABI-1179 are not yet approved, and their safety and efficacy have not been fully established.
  • Clinical development and commercialization responsibilities lie with Gilead Sciences, adding dependency risk on partner execution and strategy.
  • Risks include potential delays or failures in clinical trials and regulatory approvals impacting future prospects and stock performance.

More from Press Releases

Fiverr Announces First Quarter 2026 Results Apr 29, 2026 Nayax to Report 2026 Q1 Earnings on May 12, 2026 Apr 28, 2026 Xunlei Filed Its Annual Report on Form 20-F for Fiscal Year 2025 Apr 28, 2026 Mesoblast Achieves Patient Recruitment Target in Pivotal Phase 3 Trial for Chronic Low Back Pain Apr 28, 2026 Syntec Optics (Nasdaq: OPTX) Announces Pricing of $20 Million Underwritten Public Offering of Common Stock Apr 28, 2026