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Assembly Biosciences (NASDAQ:ASMB) is making waves in the fight against herpes simplex virus (HSV). The biotech firm recently unveiled Phase 1a clinical data for two promising new treatments, ABI-5366 and ABI-1179, at the STI & HIV 2025 World Congress and International Herpesvirus Workshop. These drug candidates, designed as helicase-primase inhibitors, are showing early signs of success, demonstrating favorable safety and pharmacokinetic profiles in healthy volunteers.
The real game-changer? Potential for significantly less frequent dosing. We’re talking about the possibility of once-weekly dosing for both treatments, and even once-monthly dosing for ABI-5366. This could dramatically improve patient compliance and quality of life, a stark contrast to the daily grind of current treatment regimens. Furthermore, data indicates that food intake does not have a clinically significant impact on the drugs’ effectiveness — good news for practical application. Both candidates are now advancing to Phase 1b trials, with interim proof-of-concept data anticipated to drop in fall 2025. Keep an eye out — these results could be a key inflection point for Assembly Biosciences.
Assembly Biosciences (NASDAQ:ASMB) ha presentato i dati clinici di Fase 1a per due nuovi trattamenti contro il virus herpes simplex (HSV), ABI-5366 e ABI-1179, durante il Congresso Mondiale STI & HIV 2025 e il Workshop Internazionale sull’Herpesvirus. I candidati farmaci, progettati come inibitori dell’elicasi-primasi, hanno mostrato profili promettenti di sicurezza e farmacocinetica in partecipanti sani.
Tra i punti salienti vi è la possibilità di una somministrazione una volta alla settimana per entrambi i trattamenti e una volta al mese per ABI-5366, rappresentando un miglioramento significativo rispetto alle attuali somministrazioni giornaliere. Entrambi i candidati non hanno mostrato effetti clinicamente rilevanti legati al cibo e stanno ora avanzando verso le sperimentazioni di Fase 1b, con dati intermedi di prova del concetto attesi per l’autunno 2025.
Assembly Biosciences (NASDAQ:ASMB) presentó datos clínicos de Fase 1a para dos nuevos tratamientos contra el virus herpes simplex (HSV), ABI-5366 y ABI-1179, en el Congreso Mundial STI & HIV 2025 y el Taller Internacional sobre Herpesvirus. Los candidatos a fármacos, diseñados como inhibidores de la helicasa-primasa, demostraron perfiles prometedores de seguridad y farmacocinética en participantes sanos.
Los aspectos destacados incluyen la posibilidad de administración semanal para ambos tratamientos y administración mensual para ABI-5366, lo que representa una mejora significativa respecto a los requisitos actuales de dosificación diaria. Ambos candidatos no mostraron efectos clínicamente significativos relacionados con los alimentos y ahora avanzan hacia ensayos de Fase 1b, con datos provisionales de prueba de concepto esperados para el otoño de 2025.
Assembly Biosciences (NASDAQ:ASMB)는 STI & HIV 2025 세계 총회 및 국제 헤르페스바이러스 워크숍에서 두 가지 새로운 단순포진 바이러스(HSV) 치료제인 ABI-5366 및 ABI-1179의 1a상 임상 데이터를 발표했습니다. 헬리케이스-프라이메이스 억제제로 설계된 이 약물 후보들은 건강한 참가자들에서 유망한 안전성 및 약동학 프로파일을 보여주었습니다.
주요 내용으로는 두 치료제 모두 주 1회 투여 가능성, 그리고 ABI-5366의 경우 월 1회 투여 가능성이 포함되어 있어 현재의 일일 투여 요구 사항에 비해 상당한 개선을 나타냅니다. 두 후보 모두 임상적으로 유의미한 음식 영향이 없었으며, 현재 1b상 시험으로 진행 중이며 2025년 가을에 중간 개념 증명 데이터가 기대됩니다.
Assembly Biosciences (NASDAQ:ASMB) a présenté des données cliniques de phase 1a pour deux nouveaux traitements contre le virus de l’herpès simplex (HSV), ABI-5366 et ABI-1179, lors du Congrès mondial STI & VIH 2025 et de l’Atelier international sur les herpèsvirus. Ces candidats médicaments, conçus comme des inhibiteurs de l’hélicase-primase, ont montré des profils prometteurs de sécurité et de pharmacocinétique chez des participants sains.
Les points clés incluent la possibilité d’une administration hebdomadaire pour les deux traitements et une administration mensuelle pour ABI-5366, ce qui représente une amélioration significative par rapport aux posologies quotidiennes actuelles. Les deux candidats n’ont montré aucun effet alimentaire cliniquement significatif et passent désormais en essais de phase 1b, avec des données intermédiaires de preuve de concept attendues à l’automne 2025。
Assembly Biosciences (NASDAQ:ASMB) präsentierte Phase-1a-Klinikdaten für zwei neue Herpes-simplex-Virus (HSV)-Behandlungen, ABI-5366 und ABI-1179, auf dem STI & HIV 2025 Weltkongress und dem Internationalen Herpesvirus-Workshop. Die Wirkstoffkandidaten, die als Helikase-Primase-Inhibitoren entwickelt wurden, zeigten vielversprechende Sicherheits- und pharmakokinetische Profile bei gesunden Teilnehmern.
Wichtige Highlights sind die Möglichkeit einer wöchentlichen Dosierung für beide Behandlungen und einer monatlichen Dosierung für ABI-5366, was eine erhebliche Verbesserung gegenüber den derzeitigen täglichen Dosierungsanforderungen darstellt. Beide Kandidaten zeigten keine klinisch signifikanten Nahrungsmittelwirkungen und gehen nun in Phase-1b-Studien über, wobei Zwischenergebnisse zum Wirkungsnachweis für Herbst 2025 erwartet werden.
Negative
- Both drug candidates are still in early clinical stages
- Efficacy data in patients with genital herpes not yet available
Insights
Assembly Bio’s herpes candidates show promising Phase 1a safety profiles, advancing to Phase 1b with potential for weekly/monthly dosing versus current daily regimens.
Assembly Biosciences has presented encouraging Phase 1a clinical data for its two herpes simplex virus (HSV) helicase-primase inhibitor candidates, ABI-5366 and ABI-1179. Both compounds demonstrated favorable safety and pharmacokinetic profiles in healthy participants, with no clinically significant food effects observed. This data supports their advancement to Phase 1b studies now underway in patients with recurrent genital herpes.
The most compelling innovation here is the potential dosing frequency. Both candidates could enable once-weekly dosing, with ABI-5366 potentially allowing once-monthly oral administration. This represents a substantial improvement over current standard-of-care therapies requiring daily dosing, significantly reducing treatment burden for patients managing this chronic condition.
ABI-1179 data is particularly noteworthy as this represents the first scientific presentation of Phase 1a results for this compound, which was contributed by Gilead Sciences under their collaboration with Assembly Bio. The company will present interim proof-of-concept Phase 1b data for both candidates in fall 2025, which will include critical antiviral activity measurements – the key functional endpoint that will determine whether these candidates can advance to later-stage development.
The HSV helicase-primase complex represents a different viral target than nucleoside analogs like valacyclovir and acyclovir that dominate current treatment. By targeting this enzyme complex essential for viral DNA replication, these candidates could potentially offer efficacy advantages beyond the convenience of reduced dosing frequency. The presentations at both conferences strengthen Assembly’s scientific positioning in this therapeutic area, where innovation has been limited for decades.
07/26/2025 – 03:00 AM
– Phase 1a clinical data in healthy participants presented for both ABI-5366 and ABI-1179, novel long-acting herpes simplex virus helicase-primase inhibitor candidates –
– Preclinical data and U.S. genital herpes prevalence and treatment patterns also highlighted –
– Interim proof-of-concept Phase 1b data in participants with recurrent genital herpes expected for both candidates in fall 2025 –
SOUTH SAN FRANCISCO, Calif., July 26, 2025 (GLOBE NEWSWIRE) — Assembly Biosciences, Inc. (Nasdaq: ASMB), a biotechnology company developing innovative therapeutics targeting serious viral diseases, today announced Phase 1a clinical and preclinical data for its herpes simplex virus (HSV) helicase-primase inhibitor candidates ABI-5366 and ABI-1179 are featured in multiple poster presentations, including one late-breaker, during the STI & HIV 2025 World Congress, taking place July 26-30, 2025, in Montreal, Canada, as well as in oral and poster presentations at the 49th Annual International Herpesvirus Workshop, taking place July 26-30, 2025, in Berlin, Germany.
“These data presented for ABI-5366 and ABI-1179 continue to support the promise of both candidates to provide important innovation that could improve quality of life for people living with recurrent genital herpes,” said Anuj Gaggar, MD, PhD, chief medical officer of Assembly Bio. “This includes the potential for once weekly, and in the case of ABI-5366, once monthly, oral dosing. These dosing options would represent a meaningful reduction in treatment burden from current standard of care therapies that require daily dosing. Both candidates are now in Phase 1b clinical evaluation in participants with recurrent genital herpes, and we look forward to sharing interim data, including antiviral activity, from these studies this fall.”
At the STI & HIV 2025 World Congress, two posters highlight the safety and pharmacokinetic (PK) profiles of ABI-5366 and ABI-1179 as observed in healthy participants in Phase 1a studies, supporting their progression to Phase 1b evaluation. The late-breaking poster for ABI-1179, the first scientific presentation of Phase 1a clinical data for this candidate, includes additional new interim data showing that, as was also the case in the ABI-5366 Phase 1a study, no clinically significant food effect was observed. Unblinded safety data for ABI-1179 are also included in this presentation.
Additional posters presented at STI & HIV 2025 review previously presented preclinical studies of ABI-5366 and provide additional methodology for the retrospective analysis of claims data estimating the prevalence of genital herpes and treatment patterns in the U.S. presented earlier this year.
At the 49th Annual International Herpesvirus Workshop, one poster presentation and one oral presentation describe the preclinical profiles of ABI-5366 and ABI-1179 and include interim safety and PK data for both candidates from the Phase 1a studies in healthy participants.
Titles of the presentations are listed below. 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.
STI & HIV 2025 World Congress
- Oral Poster Presentation: ABI-5366, a novel, oral, long-acting herpes simplex virus helicase-primase inhibitor: interim safety and pharmacokinetic results from a phase 1a study in healthy participants
- Oral Poster Presentation: ABI-5366, a potent HSV helicase-primase inhibitor, with potential for weekly or monthly oral dosing for recurrent genital herpes
- Poster Presentation: Estimating genital herpes prevalence and treatment patterns among U.S. healthcare-engaged individuals: insights from claims data
- Late-Breaker Poster Presentation: ABI-1179, a novel, orally administered, long-acting HSV helicase-primase inhibitor: interim analysis of safety and pharmacokinetic data from a phase 1a study in healthy participants
49th Annual International Herpesvirus Workshop
- Oral and Poster Presentations: ABI-5366 and ABI-1179, two potent, long-acting helicase-primase inhibitors for the treatment of recurrent genital herpes
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. ABI-1179 was contributed by Gilead Sciences, Inc. (Gilead) under the collaboration between Assembly Bio and Gilead.
About Recurrent Genital Herpes
Genital herpes is a chronic viral infection caused by the herpes simplex virus (HSV) that can result in painful genital lesions, serious psychological and social impacts, and an increased risk of acquiring human immunodeficiency virus (HIV). Epidemiologic studies estimate over four million people in the United States and France, Germany, Italy, Spain and the United Kingdom experience recurrent genital herpes, with most people with initial symptomatic genital HSV type 2 (HSV-2) infection having three or more recurrences per year. While genital herpes can be caused by either HSV type 1 (HSV-1) or HSV-2, recurrences are more likely to be experienced by individuals infected by HSV-2. The current standard of care treatment for recurrent genital herpes is nucleoside analogs given intermittently for recurrences or as daily chronic suppressive therapy; however, these are only partially effective in preventing recurrences and in reducing transmission of the virus. No new drugs have been approved in the United States or Europe to treat genital herpes for more than 25 years.
About Helicase-Primase Inhibition
HSV helicase-primase inhibitors target the viral helicase-primase complex, an essential viral enzyme complex that is conserved across both HSV-1 and HSV-2 and has no host equivalent. Inhibition of the helicase-primase complex is a clinically validated mechanism that has shown the potential for superior efficacy to the current standard of care, nucleoside analogs, in short-duration clinical studies in participants with recurrent genital herpes.
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 maintain financial resources necessary to continue its research activities, clinical studies and other business operations; Assembly Bio’s ability to realize the potential benefits of its collaboration with Gilead Sciences, Inc. (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; potential effects of changes in government regulation, including as a result of the change in U.S. administration in 2025; 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
Investor and Corporate:
Shannon Ryan
SVP, Investor Relations, Corporate Affairs and Alliance Management
(415) 738-2992
[email protected]
Media:
Sam Brown Healthcare Communications
Alyssa Kuciunas
(331) 481-3751
[email protected]
FAQ
What are the key findings from Assembly Biosciences’ (ASMB) Phase 1a trials for its herpes treatments?
The Phase 1a trials showed favorable safety and pharmacokinetic profiles for both ABI-5366 and ABI-1179, with no clinically significant food effects observed. The treatments could potentially enable once-weekly or once-monthly dosing, compared to current daily treatments.
When will Assembly Biosciences (ASMB) release Phase 1b data for its herpes treatments?
Assembly Biosciences expects to release interim proof-of-concept Phase 1b data for both ABI-5366 and ABI-1179 in fall 2025.
What is the potential advantage of Assembly Biosciences’ herpes treatments over current therapies?
The key advantage is reduced dosing frequency – once-weekly dosing for both treatments and potential once-monthly dosing for ABI-5366, compared to current standard therapies that require daily dosing.
What type of drug candidates are ABI-5366 and ABI-1179?
Both are novel herpes simplex virus (HSV) helicase-primase inhibitors designed to treat recurrent genital herpes.
Has Assembly Biosciences received FDA approval for its herpes treatments?
No, both ABI-5366 and ABI-1179 are still investigational product candidates that have not been approved anywhere globally, and their safety and efficacy have not been established.
