OS Therapies Announces Overall and Event Free Survival Key Subgroup Data for OST-HER2 in Recurrent, Fully Resected, Pulmonary Metastatic Osteosarcoma
OS Therapies (NYSE American: OSTX) announced subgroup overall survival (OS) and event-free survival (EFS) data from its 41-patient Phase 2b trial of OST-HER2 in recurrent, fully resected, pulmonary metastatic osteosarcoma dated October 22, 2025.
- Lung-only second-or-greater metastatic event: 2-year OS 80.0% (8/10) with 2 lost to follow-up; 1-year EFS 50% (6/12).
- Lung-only first metastatic event: 2-year OS 73.8% (19/26) versus a 30% natural history comparator (p < 0.0001); 1-year EFS 28.6% (8/28) with 1 lost to follow-up.
The company highlighted a favorable safety profile versus institutional chemotherapy standards and said it plans regulatory meetings with the FDA, MHRA, and EMA as it prepares BLA and MAA filings under accelerated/conditional pathways.
OS Therapies (NYSE American: OSTX) ha annunciato dati di OS (overall survival) ed EFS (event-free survival) di sottogruppo dal suo trial di fase 2b con 41 pazienti di OST-HER2 in osteosarcoma polmonare metastatico ricorrente, completamente resezioneato, datati 22 ottobre 2025.
- Evento metastatico polmonare di secondo livello o superiore: OS a 2 anni 80,0% (8/10) con 2 perso al follow-up; EFS a 1 anno 50% (6/12).
- Evento metastatico polmonare di primo livello: OS a 2 anni 73,8% (19/26) rispetto a un comparatore di storia naturale 30% (p < 0,0001); EFS a 1 anno 28,6% (8/28) con 1 perso al follow-up.
L’azienda ha evidenziato un profilo di sicurezza favorevole rispetto agli standard di chemioterapia istituzionale e ha dichiarato di pianificare incontri regolatori con la FDA, MHRA e EMA mentre prepara domande di BLA e MAA tramite percorsi accelerati/condizionali.
OS Therapies (NYSE American: OSTX) anunció datos de OS (supervivencia global) y EFS (supervivencia libre de eventos) de un subgrupo de su ensayo de fase 2b con 41 pacientes de OST-HER2 en osteosarcoma metastásico pulmonar recurrente y completamente resecado, con fecha de 22 de octubre de 2025.
- Evento metastático pulmonar en segunda o mayor instancia: OS a 2 años 80,0% (8/10) con 2 pérdidas de seguimiento; EFS a 1 año 50% (6/12).
- Evento metastático pulmonar en primera instancia: OS a 2 años 73,8% (19/26) frente a un comparador de historia natural del 30% (p < 0,0001); EFS a 1 año 28,6% (8/28) con 1 pérdida de seguimiento.
La empresa destacó un perfil de seguridad favorable frente a los estándares institucionales de quimioterapia y dijo que planifica reuniones regulatorias con la FDA, MHRA y EMA mientras prepara presentaciones de BLA y MAA bajo vías aceleradas/condicionales.
OS Therapies (NYSE American: OSTX)은 재발성, 전부 절제된 폐 전이성 골육종에서 OST-HER2의 41명 환자 2상b 임상시험의 하위군 전체생존(OS) 및 사건자유생존(EFS) 데이터를 2025년 10월 22일자로 발표했습니다.
- 폐로 한정된 2차 이상 전이 사건: 2년 OS 80.0% (8/10)로 추적 중단 2명 포함; 1년 EFS 50% (6/12).
- 폐로 한정된 1차 전이 사건: 2년 OS 73.8% (19/26)로 자연경과 비교 30% 대조군(p < 0.0001); 1년 EFS 28.6% (8/28)로 추적 중단 1명.
회사는 기관의 화학요법 기준 대비 안전성 프로필이 우수하다고 강조했으며, 가속/조건부 경로를 통해 BLA 및 MAA 제출을 준비하는 동안 FDA, MHRA 및 EMA와의 규제 회의를 계획하고 있다고 밝혔습니다.
OS Therapies (NYSE American: OSTX) a annoncé des données de survie globale (OS) et de survie sans événement (EFS) pour un sous-groupe de son essai de phase 2b à 41 patients d’OST-HER2 dans un ostéosarcome métastatique pulmonaire récurrent et entièrement réséqué, datées du 22 octobre 2025.
- Événement métastatique pulmonaire de niveau secondaire ou supérieur uniquement: OS sur 2 ans 80,0% (8/10) avec 2 perdus de suivi; EFS sur 1 an 50% (6/12).
- Événement métastatique pulmonaire de premier niveau uniquement: OS sur 2 ans 73,8% (19/26) contre un historique naturel de 30% (p < 0,0001); EFS sur 1 an 28,6% (8/28) avec 1 perdu de suivi.
La société a mis en avant un profil de sécurité favorable par rapport aux standards de chimiothérapie institutionnels et a indiqué prévoir des rencontres réglementaires avec la FDA, MHRA et EMA alors qu’elle prépare des dépôts BLA et MAA via des voies accélérées/ conditionnelles.
OS Therapies (NYSE American: OSTX) hat Subgruppen-OS- und EFS-Daten aus seiner 41-Patienten-Phase-2b-Studie von OST-HER2 beim rezidivierenden, vollständig resezierten pulmonal-metastatischen Osteosarkom veröffentlicht, datiert auf 22. Oktober 2025.
- Nur Lunge zweites oder höheres metastatisches Ereignis: 2-Jahres-OS 80,0% (8/10) mit 2 Verlegungen; 1-Jahres-EFS 50% (6/12).
- Nur Lunge erstes metastatisches Ereignis: 2-Jahres-OS 73,8% (19/26) gegenüber einem natürlichen Verlauf von 30% (p < 0,0001); 1-Jahres-EFS 28,6% (8/28) mit 1 Verlegung.
Das Unternehmen hob ein günstiges Sicherheitsprofil im Vergleich zu institutionellen Chemotherapie-Standards hervor und plant Regulierungsmeetings mit der FDA, MHRA und EMA, während es BLA- und MAA-Einreichungen über beschleunigte/bedingte Pfade vorbereitet.
OS Therapies (NYSE American: OSTX) أعلنت عن بيانات بقاء عامة فرعية (OS) وبقاء خالٍ من الأحداث (EFS) من تجربتها من المرحلة 2b التي تضم 41 مريضاً لـ OST-HER2 في أورام العظم اللابِة الرئوية النقيلية المتكررة والتي أزيلت جراحياً تماماً، بتاريخ 22 أكتوبر 2025.
- الحدث النقِّي الرئوي الثانوي أو الأعلى فقط: بقاء على قيد الحياة لمدة سنتين OS 80.0% (8/10) مع فقدان متابعة لاثنين؛ EFS لمدة سنة واحدة 50% (6/12).
- الحدث النقِّي الرئوي الأول فقط: OS لمدة سنتين 73.8% (19/26) مقابل مقارنة تاريخية طبيعية 30% (p < 0.0001); EFS لمدة سنة واحدة 28.6% (8/28) مع فقدان متابعة واحد.
سلطت الشركة الضوء على ملف أمان مفضل مقارنة بمعايير العلاج الكيميائي المؤسسية وقالت إنها تخطط لعقد اجتماعات تنظيمية مع FDA و MHRA و EMA أثناء إعداد طلبات BLA و MAA بموجب مسارات مسرّعة/شرطية.
OS Therapies (NYSE American: OSTX) 公布了其41名患者的OST-HER2第2b阶段试验在复发性、完全切除的肺部转移性骨肉瘤中的分组总体生存（OS）和无事件生存（EFS）数据，日期为2025年10月22日。
- 仅肺部的二级及以上转移事件：2年OS 80.0%（8/10），随访流失2例；1年EFS 50%（6/12）。
- 仅肺部的初次转移事件：2年OS 73.8%（19/26），对照为自然史30%（p < 0.0001）；1年EFS 28.6%（8/28），随访流失1例。
公司强调其安全性特征优于机构化化疗标准，并表示将与FDA、MHRA和EMA进行监管会晤，同时在加速/有条件路径下准备BLA和MAA申报。
- 2-year OS 80.0% in lung-only second-or-greater metastatic patients
- 2-year OS 73.8% in lung-only first metastatic patients
- 2-year OS 73.8% vs 30% comparator (p < 0.0001)
- Plans for regulatory meetings with FDA, MHRA, and EMA
- Small overall trial size: 41 patients enrolled
- Subgroup denominators small (e.g., 10 and 26 patients) reducing precision
- Lost-to-follow-up cases reduce evaluable counts (2 and 3 reported)
Insights
Phase 2b subgroup survival signals and planned regulatory interactions make this materially positive for the program.
Results show meaningful survival figures in defined subgroups: 2-year overall survival of
The path forward depends on regulatory review and confirmatory data. The company plans upcoming meetings with the FDA, MHRA and EMA, intends to pursue a BLA under Accelerated Approval and MAAs via Conditional Approval, and will present pending biomarker and post-market confirmatory trial design. Key risks embedded in the disclosed facts include small subgroup sizes, instances of lost-to-follow-up, and reliance on subgroup analyses rather than prespecified primary endpoints; each of these can limit regulatory confidence and generalizability.
Watch for: (1) the outcomes and minutes of the stated regulatory meetings, (2) the released biomarker data, and (3) the design details and timelines for the post-market confirmatory OST-HER2 metastatic osteosarcoma trial. These items will determine whether the program can convert the Phase 2b survival signal into an accelerated approval filing and required confirmatory pathway.
New York, New York--(Newsfile Corp. - October 22, 2025) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), a clinical-stage cancer immunotherapy and antibody drug conjugate biotechnology company, today announced additional overall and event free survival data generated from the Company's 41-patient Phase 2b clinical trial of its off-the-shelf immunotherapeutic candidate OST-HER2 in recurrent, fully resected, pulmonary metastatic osteosarcoma (the "Phase 2b Osteosarcoma Trial"). The Company previously announced statistically significant positive final 2-year overall survival data from its Phase 2b Osteosarcoma Trial on October 10, 2025. The Company performed these subgroup analyses following its participation in the October 10, 2025 FDA/The Osteosarcoma Institute (OSI) Workshop: Advancing Osteosarcoma Drug Development - Connecting Research and Regulatory Pathways for Improved Outcomes.
- Patients with a lung-only second or greater metastatic event:
- 2-year Overall Survival:
80.0% (8/10, 2 lost to follow-up) - 1-year Event Free Survival:
50% (6/12, 0 lost to follow-up)
- 2-year Overall Survival:
- Patients with a lung-only first metastatic event:
- 2-year Overall Survival:
73.8% (19/26, 3 lost to follow-up) vs.30% Natural History Comparator (p < 0.0001)[1] - 1-year Event Free Survival:
28.6% (8/28, 1 Lost to follow-up)
- 2-year Overall Survival:
"There was significant interest in the different patient subgroups that made up our study given the challenges typically seen in recruiting for clinical trials in osteosarcoma, especially with patients' first metastatic event for which we have sufficient data to perform this subgroup analysis," said Paul Romness, MPH, Chairman & CEO of OS Therapies. "We believe the favorable safety profile when compared with alternative institutional standards of care that rely primarily on chemotherapeutic agents played a significant role in that. The recruitment of patients into our study seems representative of the overall annual patient population and the overall survival efficacy signal appears broadly across the different subgroups of patients in our trial."
Mr. Romness continued, "We are looking forward to upcoming regulatory meetings with the U.S. Food & Drug Administration ('FDA'), the U.K. Medicines and Healthcare products Regulatory Agency ('MHRA') and the European Medicines Agency ('EMA') to review our overall survival data, pending biomarker data and post-market confirmatory OST-HER2 metastatic osteosarcoma trial design as we prepare to file a Biologics License Authorization (BLA) under the FDA's Accelerated Approval Program and Marketing Authorization Applications (MAAs) utilizing MHRA and EMA's Conditional Approval pathway."
About OS Therapies
OS Therapies is a clinical stage oncology company focused on the identification, development, and commercialization of treatments for Osteosarcoma (OS) and other solid tumors. OST-HER2, the Company's lead asset, is an immunotherapy leveraging the immune-stimulatory effects of Listeria bacteria to initiate a strong immune response targeting the HER2 protein. OST-HER2 has received Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and Fast-Track and Orphan Drug designations from the U.S. FDA and European Medicines Agency. The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma, demonstrating statistically significant benefit in the 12-month event free survival (EFS) primary endpoint of the study. The Company anticipates submitting a Biologics Licensing Application (BLA) to the U.S. FDA for OST-HER2 in osteosarcoma in 2025 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. OST-HER2 has completed a Phase 1 clinical study primarily in breast cancer patients, in addition to showing preclinical efficacy data in various models of breast cancer. OST-HER2 has been conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma.
In addition, OS Therapies is advancing its next-generation Antibody Drug Conjugate (ADC) and Drug Conjugates (DC), known as tunable ADC (tADC), which features tunable, tailored antibody-linker-payload candidates. This platform leverages the Company's proprietary silicone Si-Linker and Conditionally Active Payload (CAP) technology, enabling the delivery of multiple payloads per linker. For more information, please visit www.ostherapies.com.
Forward-Looking Statements
Statements in this press release about future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute forward-looking statements within the meaning of the federal securities laws. These forward-looking statements and terms such as "anticipate," "expect," "intend," "may," "will," "should" or other comparable terms involve risks and uncertainties because they relate to events and depend on circumstances that will occur in the future. Those statements include statements regarding the intent, belief or current expectations of OS Therapies and members of its management, as well as the assumptions on which such statements are based. OS Therapies cautions readers that forward-looking statements are based on management's expectations and assumptions as of the date of this press release and are subject to certain risks and uncertainties that could cause actual results to differ materially, including, but not limited to the approval of OST-HER2 by the U.S. FDA and other risks and uncertainties described in "Risk Factors" in the Company's most recent Annual Report on Form 10-K, most recent Quarterly Report on Form 10-Q and other subsequent documents the Company files with the Securities and Exchange Commission. Any forward-looking statements contained in this press release speak only as of the date hereof, and, except as required by the federal securities laws, OS Therapies specifically disclaims any obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise.
OS Therapies Contact Information:
Investor Relations
Harrison Seidner, PhD
WaterSeid Partners
OSTX@waterseid.com
Public Relations
Jessica Starman, MBA
Elev8 New Media
media@ostherapies.com
https://x.com/OSTherapies
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https://www.linkedin.com/company/os-therapies/
To view the source version of this press release, please visit https://www.newsfilecorp.com/release/271441
FAQ
What 2-year overall survival did OSTX report for lung-only second-or-greater metastatic osteosarcoma on October 22, 2025?
How did OSTX's 2-year OS for first lung-only metastatic events compare to natural history on October 22, 2025?
What 1-year event-free survival (EFS) rates did OSTX report for OST-HER2 subgroups?
How many patients were enrolled in the OST-HER2 Phase 2b osteosarcoma trial (OSTX)?
Will OST Therapies pursue regulatory filings after the October 22, 2025 data update for OSTX?
