Seres Therapeutics Receives Feedback From FDA on SER-155 Allogeneic Hematopoietic Stem Cell Transplant (allo-HSCT) Development Approach
Seres Therapeutics (MCRB) has received FDA feedback on its SER-155 development strategy for allogeneic hematopoietic stem cell transplant (allo-HSCT) patients. The FDA supported using reduction in bloodstream infections at 30 days post-HSCT as the primary endpoint for the next study, recommending it be a Phase 2 trial.
The company is considering either a Phase 2 or a Phase 2/3 design for operational efficiency and plans to submit the protocol to FDA in Q2 2024. The upcoming study will build on the successful Phase 1b Cohort 2 trial, which demonstrated a 77% relative risk reduction in bloodstream infections, reduced systemic antibiotic exposure, and lower febrile neutropenia incidence.
Seres is actively seeking a development partner for SER-155 in allo-HSCT and awaits additional FDA feedback on submitted clarification questions.
Seres Therapeutics (MCRB) ha ricevuto un feedback dalla FDA sulla sua strategia di sviluppo per il SER-155 destinato ai pazienti sottoposti a trapianto di cellule staminali ematopoietiche allogeniche (allo-HSCT). La FDA ha supportato l'uso della riduzione delle infezioni del flusso sanguigno a 30 giorni dopo l'HSCT come obiettivo primario per il prossimo studio, raccomandando che sia un trial di Fase 2.
L'azienda sta considerando un design di Fase 2 o di Fase 2/3 per un'efficienza operativa e prevede di presentare il protocollo alla FDA nel secondo trimestre del 2024. Il prossimo studio si baserà sul successo del trial di Fase 1b Coorte 2, che ha dimostrato una riduzione relativa del rischio del 77% nelle infezioni del flusso sanguigno, una riduzione dell'esposizione agli antibiotici sistemici e una minore incidenza di neutropenia febbrile.
Seres sta attivamente cercando un partner di sviluppo per il SER-155 nell'allo-HSCT e attende ulteriori feedback dalla FDA sulle domande di chiarimento inviate.
Seres Therapeutics (MCRB) ha recibido comentarios de la FDA sobre su estrategia de desarrollo para el SER-155 destinado a pacientes sometidos a trasplante de células madre hematopoyéticas alogénicas (allo-HSCT). La FDA apoyó el uso de la reducción de infecciones en el torrente sanguíneo a los 30 días después del HSCT como el objetivo primario para el próximo estudio, recomendando que sea un ensayo de Fase 2.
La empresa está considerando un diseño de Fase 2 o de Fase 2/3 para mayor eficiencia operativa y planea presentar el protocolo a la FDA en el segundo trimestre de 2024. El próximo estudio se basará en el exitoso ensayo de Fase 1b Cohorte 2, que demostró una reducción del riesgo relativo del 77% en infecciones del torrente sanguíneo, una reducción de la exposición a antibióticos sistémicos y una menor incidencia de neutropenia febril.
Seres está buscando activamente un socio de desarrollo para el SER-155 en allo-HSCT y espera comentarios adicionales de la FDA sobre las preguntas de aclaración enviadas.
세레스 테라퓨틱스 (MCRB)는 동종 조혈모세포 이식(allo-HSCT) 환자를 위한 SER-155 개발 전략에 대한 FDA의 피드백을 받았습니다. FDA는 HSCT 후 30일 이내의 혈류 감염 감소를 다음 연구의 주요 목표로 삼는 것을 지지하며, 이를 2상 시험으로 권장했습니다.
회사는 운영 효율성을 위해 2상 또는 2/3상 디자인을 고려하고 있으며, 2024년 2분기에 FDA에 프로토콜을 제출할 계획입니다. 다가오는 연구는 혈류 감염에서 77%의 상대 위험 감소를 입증한 성공적인 1b상 코호트 2 시험을 기반으로 할 것입니다.
세레스는 allo-HSCT에서 SER-155의 개발 파트너를 적극적으로 찾고 있으며, 제출된 명확화 질문에 대한 추가 FDA 피드백을 기다리고 있습니다.
Seres Therapeutics (MCRB) a reçu un retour de la FDA concernant sa stratégie de développement pour le SER-155 destiné aux patients ayant reçu une greffe de cellules souches hématopoïétiques allogéniques (allo-HSCT). La FDA a soutenu l'utilisation de la réduction des infections dans le sang à 30 jours après la HSCT comme principal critère d'évaluation pour la prochaine étude, recommandant qu'il s'agisse d'un essai de Phase 2.
L'entreprise envisage un design de Phase 2 ou de Phase 2/3 pour une efficacité opérationnelle et prévoit de soumettre le protocole à la FDA au deuxième trimestre 2024. La prochaine étude s'appuiera sur le succès de l'essai de Phase 1b Cohorte 2, qui a montré une réduction relative du risque de 77% des infections sanguines, une exposition systémique réduite aux antibiotiques et une incidence plus faible de neutropénie fébrile.
Seres recherche activement un partenaire de développement pour le SER-155 dans l'allo-HSCT et attend des retours supplémentaires de la FDA sur les questions de clarification soumises.
Seres Therapeutics (MCRB) hat Feedback von der FDA zu seiner Entwicklungsstrategie für SER-155 bei Patienten mit allogenem hämatopoetischem Stammzelltransplantat (allo-HSCT) erhalten. Die FDA unterstützte die Verwendung der Reduzierung von Blutstrominfektionen 30 Tage nach der HSCT als primären Endpunkt für die nächste Studie und empfahl, dass es sich um eine Phase-2-Studie handelt.
Das Unternehmen erwägt ein Design der Phase 2 oder Phase 2/3 zur operativen Effizienz und plant, das Protokoll im 2. Quartal 2024 bei der FDA einzureichen. Die bevorstehende Studie wird auf der erfolgreichen Phase-1b Kohorte 2-Studie aufbauen, die eine relative Risikominderung von 77% bei Blutstrominfektionen, eine reduzierte systemische Antibiotika-Exposition und eine geringere Inzidenz von febriler Neutropenie zeigte.
Seres sucht aktiv einen Entwicklungspartner für SER-155 im Bereich allo-HSCT und wartet auf weiteres Feedback von der FDA zu den eingereichten Klarstellungsfragen.
- 77% relative risk reduction in bloodstream infections in Phase 1b trial
- FDA supports proposed primary endpoint
- Breakthrough Therapy designation benefits
- Significant reduction in antibiotic exposure demonstrated
- Seeking development partner indicates need for additional funding/resources
- Further FDA clarifications pending before protocol submission
Insights
The FDA feedback on Seres Therapeutics' SER-155 development plan represents a significant regulatory milestone that helps derisk the clinical pathway for this potentially important therapeutic. The agency's support for using reduction in bloodstream infections as the primary endpoint maintains alignment with the impressive
The Breakthrough Therapy designation provides Seres with enhanced FDA interactions and potential for expedited review, reflecting the agency's recognition of SER-155's potential to address a serious condition with preliminary clinical evidence indicating substantial improvement over available therapies. This designation carries tangible regulatory advantages that can accelerate development timelines.
Seres' consideration of a combined Phase 2/3 study versus separate trials represents a critical strategic decision. A combined approach could significantly compress the development timeline and reduce overall program costs, potentially accelerating time-to-market by 1-2 years if successful. However, this approach requires greater upfront investment and carries higher risk if results disappoint.
The company's pursuit of a development partner signals awareness of capital requirements for late-stage development. For investors, partnership terms and structure will be important to assess the program's value retention versus dilution of commercial rights. The timing of protocol submission in Q2 establishes a clear near-term catalyst that may coincide with partnership announcements.
The bloodstream infection reduction endpoint endorsed by FDA for SER-155 addresses a critical clinical need in transplant medicine. Allogeneic stem cell transplant patients experience profound immunosuppression, making infections a leading cause of morbidity and mortality. The
Beyond the primary endpoint, the observed reductions in systemic antibiotic exposure and febrile neutropenia are clinically meaningful secondary benefits. Reduced antibiotic use helps mitigate antimicrobial resistance development and associated toxicities, while decreased febrile neutropenia events reduce hospitalization requirements and supportive care needs.
SER-155 represents a paradigm shift in approach - rather than treating infections after they occur, it aims to prevent them by modulating the microbiome that serves as a key immune regulator. This preventative strategy targets the microbiome disruption caused by pre-transplant conditioning regimens that facilitates pathogen colonization and subsequent infection.
The therapeutic's mechanism leverages commensal organisms to outcompete pathogens and modulate immune function - a fundamentally different approach from traditional antibiotics. If successful in larger trials, SER-155 could establish microbiome-based therapeutics as a new pillar in transplant medicine, potentially extending to other immunocompromised populations like solid organ transplant recipients and cancer patients undergoing intensive chemotherapy.
FDA has provided input on key elements of the SER-155 allo-HSCT clinical development plans including support for the proposed primary efficacy endpoint of reduction in bloodstream infections (BSIs) as of 30 days post HSCT in the next study
Seres has submitted clarification questions to FDA and expects a response in the coming weeks, which will inform the proposed protocol for the next SER-155 study in allo-HSCT, which the Company anticipates submitting to FDA in Q2
CAMBRIDGE, Mass., March 03, 2025 (GLOBE NEWSWIRE) -- Seres Therapeutics, Inc. (Nasdaq: MCRB) (Seres or the Company), a leading live biotherapeutics company, today announced that it has received constructive feedback from a Type B Breakthrough Therapy designation engagement with the U.S. Food and Drug Administration (FDA or the agency) regarding the Company’s development strategy for its lead live biotherapeutic, SER-155 in patients undergoing allo-HSCT. The FDA provided feedback on important elements of the next study that included a recommendation that it be a Phase 2 and support for a reduction in bloodstream infections as of 30 days post HSCT as the primary endpoint; and confirmed their expectations for the manufacture and control of SER-155. Further interaction with FDA is expected in the coming weeks as the Company has submitted questions to clarify certain feedback received. Seres is evaluating the next study design, which could be either a Phase 2, or a Phase 2/3 that offers operational efficiencies, and anticipates submitting a proposed protocol, incorporating FDA’s feedback, for the next study of SER-155 in allo-HSCT to the agency in the second quarter of this year.
“We are pleased to have obtained productive FDA feedback supporting our goal of bringing SER-155 to allo-HSCT patients,” said Eric Shaff, President and Chief Executive Officer of Seres Therapeutics. “Obtaining FDA’s input is vital to aligning on our development approach, consistent with the benefits provided by Breakthrough Therapy designation, and to derisking the regulatory path forward. Based on the guidance and pending further FDA feedback, we expect to submit a protocol for our next study to the agency in the second quarter and look forward to further FDA engagement on the SER-155 development plan. Notably, the next study design is expected to retain many of the elements of our SER-155 placebo controlled Phase 1b Cohort 2 trial in allo-HSCT, which showed an impressive
About SER-155
SER-155 is an investigational, oral, live biotherapeutic designed to decolonize GI pathogens, improve epithelial barrier integrity, and induce immune tolerance to prevent bacterial bloodstream and antimicrobial resistant (AMR) infections, as well as other pathogen associated negative clinical outcomes, in patients undergoing allo-HSCT for the treatment of hematological malignancies.
SER-155 has been evaluated in a Phase 1b placebo-controlled study in patients undergoing allo-HSCT, which demonstrated a significant reduction in both BSIs (
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 timing and results of our clinical studies and data readouts; our clinical development plans; communications with, feedback from, or submissions to the FDA; the impact, value or potential benefits of Breakthrough Therapy designation, Fast Track designation or any other regulatory designations; our ability to secure a partnership and/or generate additional capital; the 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) if we are not able to obtain, or if there are delays in obtaining, required regulatory approvals, we or any collaborators will not be able to commercialize our product candidates or will not be able to do so as soon as anticipated; (2) we have incurred significant losses, are not currently profitable and may never become profitable; (3) our need for additional funding; (4) our history of operating losses; (5) our novel approach to therapeutic intervention; (6) our reliance on third parties to conduct our clinical trials and manufacture our product candidates; (7) the competition we will face; (8) our ability to protect our intellectual property; (9) our ability to retain key personnel and to manage our growth; (10) the effect of the VOWST sale on our ability to retain and hire key personnel and maintain relationships with our customers, suppliers, advertisers, partners and others with whom we do business, or on our operating results and businesses generally; (11) the risks associated with the disruption of management’s attention from ongoing business operations due to the obligation to provide transition services; (12) our failure to receive the installment payment or the milestone payments in the future; (13) the uncertainty of impact of the 50/50 profit and loss sharing arrangement on our reported results and liquidity; and (14) we may not be able to realize the anticipated benefits of the VOWST sale. 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 November 13, 2024, and 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 Contacts:
IR@serestherapeutics.com
Carlo Tanzi, Ph.D.
Kendall Investor Relations
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