Seres Therapeutics to Present New Post Hoc Data From SER-155 Phase 1b Trial at IDWeek 2025, Highlighting Potential to Improve Outcomes in Adults Undergoing Allogeneic Hematopoietic Stem Cell Transplant
Seres Therapeutics (Nasdaq: MCRB) announced new post hoc data from the SER-155 Phase 1b trial will be presented orally at IDWeek 2025 on October 20, 2025. The presentation reports differences between SER-155 and placebo in bacterial and fungal bloodstream infection (BSI) pathogens, clinical BSI outcomes, antibacterial prophylaxis use, and antimicrobial resistance patterns.
Key disclosed result: in the randomized, double-blind Phase 1b cohort, SER-155 reduced BSIs by 77% and lowered systemic antibiotic use and febrile neutropenia. The company said it received constructive FDA feedback on a well-powered Phase 2 design and is finalizing the protocol while pursuing capital to advance SER-155 and its live biotherapeutics portfolio.
Seres Therapeutics (Nasdaq: MCRB) ha annunciato che nuovi dati post hoc dallo studio SER-155 di Fase 1b saranno presentati oralmente a IDWeek 2025 il 20 ottobre 2025. La presentazione riporta differenze tra SER-155 e placebo nei patogeni di infezione sanguigna batterica e fungina (BSI), esiti clinici di BSI, uso di profilassi antibiotica e modelli di resistenza antimicrobica.
Risultato chiave divulgato: nella coorte randomizzata in doppio cieco di Fase 1b, SER-155 ha ridotto le BSI del 77% e ha diminuito l'uso di antibiotici sistemici e la neutropenia febbrile. L'azienda ha detto di aver ricevuto feedback costruttivo dalla FDA su un disegno di Fase 2 ben potenziato e sta finalizzando il protocollo mentre cerca capitali per avanzare SER-155 e il suo portafoglio di live biotherapeutics.
Seres Therapeutics (Nasdaq: MCRB) anunció que nuevos datos post hoc del ensayo SER-155 de Fase 1b serán presentados oralmente en IDWeek 2025 el 20 de octubre de 2025. La presentación informa diferencias entre SER-155 y placebo en patógenos de infecciones bacterianas y fúngicas en la sangre (BSI), resultados clínicos de BSI, uso de profilaxis antibacteriana y patrones de resistencia antimicrobiana.
Resultado clave divulgado: en la cohorte aleatorizada y doble ciego de Fase 1b, SER-155 redujo las BSI en un 77% y redujo el uso de antibióticos sistémicos y neutropenia febril. La empresa afirmó haber recibido retroalimentación constructiva de la FDA sobre un diseño de Fase 2 bien potenciado y está finalizando el protocolo mientras busca capital para avanzar con SER-155 y su cartera de bio-terapéuticos vivos.
Seres Therapeutics (나스닥: MCRB)는 SER-155 1b상(Fase 1b) 시험의 새로운 사후 분석(post hoc) 데이터가 2025년 10월 20일 IDWeek 2025에서 구두 발표될 것이라고 발표했다. 발표에서는 SER-155와 위약의 혈액 내 박테리아 및 진균계 BSI 병원체, BSI 임상 결과, 항생제 예방 사용, 항미생제 내성 패턴의 차이를 보고한다.
주요 공개 결과: 무작위 이중맹검 1b 코호트에서 SER-155가 BSI를 77% 감소했고 전신 항생제 사용 및 발열성 호중구감소증을 낮췄다. 회사는 강력한 파이즈 2 설계에 대한 건설적인 FDA 피드백을 받았으며 프로토콜을 확정하는 한편 SER-155와 살아있는 생균제 포트폴리오를 발전시키기 위한 자본 조달을 추진 중이라고 밝혔다.
Seres Therapeutics (Nasdaq: MCRB) a annoncé que de nouveaux données post hoc de l'essai SER-155 de phase 1b seront présentées oralement à IDWeek 2025 le 20 octobre 2025. La présentation rapporte des différences entre SER-155 et le placebo dans les agents pathogènes d'infection sanguine bactérienne et fongique (BSI), les résultats cliniques de BSI, l'utilisation de prophylaxie antibiotique et les schémas de résistance antimicrobienne.
Résultat clé divulgué: dans la cohorte randomisée et en double aveugle de la Phase 1b, SER-155 a réduit les BSI de 77% et a diminué l'utilisation d'antibiotiques systémiques et la neutropénie fébrile. L'entreprise a déclaré avoir reçu des retours constructifs de la FDA sur une conception de Phase 2 bien alimentée et finalise le protocole tout en recherchant des capitaux pour faire progresser SER-155 et son portefeuille de biothérapies vivantes.
Seres Therapeutics (Nasdaq: MCRB) gab bekannt, dass neue post hoc-Daten aus der SER-155-Phase-1b-Studie am IDWeek 2025 am 20. Oktober 2025 mündlich vorgestellt werden. Die Präsentation berichtet Unterschiede zwischen SER-155 und Placebo bei bakteriellen und pilzbedingten BSI-Erregern, klinischen BSI-Ergebnissen, Verwendung von antibakterieller Prophylaxe und Mustern der antimikrobiellen Resistenzen.
Wesentlich offengelegtes Ergebnis: In der randomisierten, doppelblinden Phase-1b-Kohorte reduzierte SER-155 BSI um 77% und senkte den systemischen Antibiotikaeinsatz sowie die febrile Neutropenie. Das Unternehmen gab an, konstruktives FDA-Feedback zu einem gut gestützten Phase-2-Design erhalten zu haben und finalisiert das Protokoll, während es Kapital beschafft, um SER-155 und sein Portfolio an Live-Biotherapeutika voranzubringen.
Seres Therapeutics (ناسداك: MCRB) أعلنت أن بيانات جديدة لاحقة التحليل post hoc من تجربة SER-155 من المرحلة 1b ستقدم شفوياً في IDWeek 2025 في 20 أكتوبر 2025. تشير العروض إلى الاختلافات بين SER-155 ووهم placebo في مسببات عدوى الدم البكترية والفطرية (BSI)، نتائج BSI السريرية، استخدام الوقاية من المضادات الحيوية، وأنماط مقاومة مضادات الميكروبات.
النتيجة الرئيسية المعلنة: في كلّ cohort عشوائي مزدوج التعمية من المرحلة 1b، قللت SER-155 BSI بنسبة 77% وخفضت استخدام المضادات الحيوية الجهازية والحمّى النخاعية. قالت الشركة إنها تلقت تعليقات بناءة من FDA حول تصميم مرحلة 2 المدعوم جيداً وتقوم بإتمام البروتوكول بينما تسعى إلى رأس المال للمضي قدماً بـ SER-155 ومحفظة المستمثرات الحية.
Seres Therapeutics (纳斯达克: MCRB) 宣布，来自 SER-155 1b 期研究的新事后数据将于 IDWeek 2025 在 2025 年 10 月 20 日口头提交。报告比较 SER-155 与安慰剂在血液传播的细菌和真菌性BSI病原体、BSI的临床结局、抗菌药预防使用以及抗菌耐药性模式的差异。
关键信息披露：在随机、双盲的 1b 期队列中，SER-155 将 BSI 降低了 77%，并降低了全身抗生素使用量及发热性中性粒细胞减少。公司表示已就一个高效的 Phase 2 设计获得 FDA 的建设性反馈，并在完善方案的同时寻求资本以推进 SER-155 及其活性生物治疗产品组合。
- BSIs reduced by 77% in Phase 1b randomized cohort
- Lowered systemic antibiotic use and febrile neutropenia reported
- Constructive FDA feedback received on Phase 2 study design
- None.
CAMBRIDGE, Mass., Oct. 14, 2025 (GLOBE NEWSWIRE) -- Seres Therapeutics, Inc. (Nasdaq: MCRB), (Seres or the Company), a leading live biotherapeutics company, today announced that new post hoc data from its SER-155 Phase 1b trial will be featured in an oral presentation at IDWeek 2025, taking place October 19–22 in Atlanta, Georgia.
Presentation Details
Abstract ID: 2106936
Title: Clinical and Microbiology Outcomes of Bloodstream Infections (BSI) in Adults Undergoing Allogeneic Hematopoietic Stem Cell Transplant (allo-HCT) in a Randomized, Double-blind, Placebo-controlled Cohort 2 of a Phase 1b Study of SER-155, an Investigation Live Biotherapeutic
Presenter: Tessa Andermann, MD, MPH; Associate Professor of Medicine, Division of Infectious Diseases, University of North Carolina at Chapel Hill School of Medicine
Session: Blood and Guts – Microbiome Discoveries
Date and Time: October 20, 10:30-10:42am EDT
Location: B207-B208, Georgia World Congress Center
The presentation will include new data describing differences between the SER-155 and placebo groups in the bacterial and fungal organisms causing BSIs, including BSI event clinical outcomes, antibacterial prophylaxis use, and patterns of antimicrobial resistance (AMR) among the bacterial BSI organisms.
In a randomized, placebo-controlled Phase 1b study evaluating SER-155 in patients receiving allo-HSCT, SER-155 reduced BSIs by
The Company recently received constructive FDA feedback on the design of a well-powered, placebo-controlled Phase 2 study of SER-155 in patients receiving allo-HSCT and is finalizing the clinical protocol. Seres is also engaged in discussions with multiple parties to secure capital and additional resources to advance SER-155 and its broader live biotherapeutics portfolio.
IDWeek is an annual meeting organized by a collaboration of professional organizations, including the Infectious Diseases Society of America (IDSA), the Society for Healthcare Epidemiology of America (SHEA), the HIV Medicine Association (HIVMA), the Pediatric Infectious Diseases Society (PIDS), and the Society of Infectious Diseases Pharmacists (SIDP).
About Seres Therapeutics
Seres Therapeutics, Inc. (Nasdaq: MCRB) is a clinical-stage company focused on improving patient outcomes in medically vulnerable populations through novel live biotherapeutics. Seres led the successful development and approval of VOWST™, the first FDA-approved orally administered microbiome therapeutic, which was sold to Nestlé Health Science in September 2024. The Company is developing SER-155, which has received Breakthrough Therapy designation for the reduction of bloodstream infections in adults undergoing allo-HSCT and Fast Track designation for reducing the risk of infection and graft-versus-host disease in adults undergoing allo-HSCT, and which has demonstrated a significant reduction in bloodstream infections and related complications (as compared to placebo) in a Phase 1b clinical study in patients undergoing allo-HSCT. SER-155 and the Company's other pipeline programs are designed to target multiple disease-relevant pathways and are manufactured from standard clonal cell banks via cultivation, rather than from the donor-sourced production process used for VOWST. In addition to allo-HSCT, the Company intends to evaluate SER-155 and other cultivated live biotherapeutic candidates in other medically vulnerable patient populations including autologous-HSCT patients, cancer patients with neutropenia, CAR-T recipients, individuals with chronic liver disease, solid organ transplant recipients, as well as patients in the intensive care unit and long-term acute care facilities. For more information, please visit www.serestherapeutics.com.
Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including statements about: the anticipated content and timing of our presentation at IDWeek 2025; timing and results of our clinical studies and data readouts, including the interpretation and potential implications of new post hoc data from the SER-155 Phase 1b trial; current or future product candidates and their potential benefits; clinical development plans and commercial opportunities; communications with, feedback from, or submissions to, the FDA; our plans and expectations regarding the design and finalization of a Phase 2 study of SER-155; our clinical development plans for SER-155 and other cultivated live biotherapeutic candidates across medically vulnerable populations; our ability to secure capital and additional resources; our planned strategic focus; the anticipated timing of any of the foregoing; and other statements that are not historical fact.
These forward-looking statements are based on management’s current expectations. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: (1) our need for additional funding; (2) our ability to continue as a going concern; (3) we have incurred significant losses, are not currently profitable and may never become profitable; (4) our cost reduction actions may not achieve their intended benefits, including an extended cash runway; (5) our limited operating history; (6) the expected payments from the VOWST sale are subject to risks and uncertainties; (7) we may not be able to realize the anticipated benefits of the VOWST sale, and may face new challenges as a smaller, less diversified company; (8) we have in the past and may in the future receive notice of the failure to satisfy a continued listing rule from The Nasdaq Stock Market LLC; (9) our novel approach to therapeutic intervention; (10) our reliance on third parties to conduct our clinical trials and manufacture our product candidates; (11) our ability to achieve market acceptance necessary for commercial success; (12) the competition we will face; (13) our ability to protect our intellectual property; and (14) our ability to manage our recent CEO transition, to retain key personnel and to manage our growth. These and other important factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on August 6, 2025, as well as our other reports filed with the SEC, could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this press release.
Investor and Media Contact:
IR@serestherapeutics.com
Carlo Tanzi, Ph.D.
Kendall Investor Relations
ctanzi@kendallir.com
FAQ
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