OS Therapies Announces the Publication of Four Articles on OST-HER2 and Osteosarcoma in Drug Discovery World
Rhea-AI Summary
OS Therapies (NYSE American: OSTX) announced the publication of four Drug Discovery World articles on OST-HER2 and osteosarcoma, covering treatment futures, comparative oncology, regulatory science and accelerated approval. The company plans to present 2.5-year overall survival data from its Phase 2b OST-HER2 trial at ASCO 2026.
OST-HER2 holds ODD, FTD and RPDD from the FDA, plus ODD, FTD and ATMP from the EMA. OS Therapies is seeking a BLA under the U.S. Accelerated Approval Program in the second half of 2026 and related conditional approvals in Europe, the U.K. and Australia.
Positive
- OST-HER2 granted FDA ODD, FTD and Rare Pediatric Disease designations
- OST-HER2 granted EMA ODD, FTD and ATMP classifications
- Planned U.S. BLA submission under Accelerated Approval in second half of 2026
- Planned conditional marketing authorization filings in Europe, U.K. and Australia
- Upcoming 2.5-year overall survival Phase 2b data presentation at ASCO 2026
- RPDD may make OST-HER2 eligible for a tradable Priority Review Voucher if BLA is approved
Negative
- None.
News Market Reaction – OSTX
In the May 29 session, OSTX gained 8.08%, reflecting a notable positive market reaction. Argus tracked a peak move of +5.8% during that session. Our momentum scanner triggered 22 alerts that day, indicating elevated trading interest and price volatility. Trading volume was above average at 1.8x the daily average, suggesting increased trading activity.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Historical Context
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| May 26 | Conference participation | Positive | +1.2% | Planned presentation of 2.5-year survival data and multiple 2026 conferences. |
| May 18 | Q1 2026 earnings | Negative | -8.0% | Larger net operating loss and going-concern pressures despite recent capital raises. |
| May 15 | Earnings date notice | Neutral | -8.0% | Announcement of upcoming Q1 2026 financials and business update timing. |
| May 14 | Leadership appointment | Positive | +5.0% | Appointment of Chief Medical Advisor to support OST-HER2 regulatory strategy. |
| May 12 | Analyst coverage | Positive | +0.0% | Updated coverage highlighting EMA rolling review and key 2026 OST-HER2 milestones. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Shares have tended to react positively to clinical/regulatory progress and negatively around earnings and financing-related updates, with some divergence when neutral or positive news did not move the stock.
Recent news for OSTX has centered on OST‑HER2 clinical progress, financing, and regulatory milestones. In March–April 2026, filings highlighted conditional EMA review, financing transactions, and going-concern risks. In May 2026, coverage updates, a key medical advisor appointment, and Q1 results framed both opportunity and balance-sheet pressure. Today’s announcement reinforces the OST‑HER2 narrative and upcoming 2.5‑year survival data, continuing the focus on regulatory positioning and clinical validation in osteosarcoma.
Key Terms
overall survival medical
phase 2b medical
orphan drug designation regulatory
fast track designation regulatory
rare pediatric disease designation regulatory
atmp regulatory
biologics license application regulatory
accelerated approval program regulatory
AI-generated analysis. How Rhea-AI works. Not financial advice.
- The Company confirms that it will release 2.5 year overall survival data from Phase 2b clinical trial OST-HER2 in the prevention or delay of recurrence in fully-resected pulmonary metastatic osteosarcoma during the 2026 American Society of Clinical Oncologists (ASCO) Annual Meeting being held from May 28, 2026 to June 2, 2026.
New York, New York and Rockville, Maryland--(Newsfile Corp. - May 29, 2026) - OS Therapies, Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in gene-edited, listeria-based cancer immunotherapies, today announced the publication of four articles related to OST-HER2 and/or Osteosarcoma in Drug Discovery World.
Looking back to see forward: The future of osteosarcoma treatment
Publication Date: December 8, 2025Comparative Oncology in Osteosarcoma: leveraging canine disease to drive drug discovery and validation of biomarkers and accelerate the pathway to new therapies
Publication Date: February 23, 2026Novel regulatory science considerations in osteosarcoma: the imperative for regulatory flexibility to meet critical unmet patient and clinical needs
Publication Date: May 21, 2026The case for accelerated approval in recurrent osteosarcoma
Publication Date: May 29, 2026
Concurrent with this announcement, the Company reiterated that it will release 2.5 year overall survival data from Phase 2b clinical trial OST-HER2 in the prevention or delay of recurrence in fully-resected pulmonary metastatic osteosarcoma during the 2026 ASCO Annual Meeting being held from May 28, 2026 to June 2, 2026.
OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD) and Rare Pediatric Disease Designation (RPDD) from the FDA, and ODD, FTD and ATMP from the EMA. Under the RPDD program, if the Company receives a BLA in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The Company is seeking to obtain a BLA under the Accelerated Approval Program in U.S. for OST-HER2 in osteosarcoma in the second half of 2026, in addition to CMAs in Europe, the U.K. and Australia.
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. The Company is the world leader in listeria-based cancer immunotherapies. 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 is designed to target two mutated extracellular epitopes and one mutated intracellular epitope of the HER2 oncogene, requiring only one of these three epitopes to be present in a tumor (or micro-metastasis) to trigger the desired immune response. OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD) and Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and has received ODD, FTD and ATMP from the 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 clinically significant benefit in the 12-month event free survival (EFS) primary endpoint of the study and the overall survival (OS) secondary endpoint. The Company anticipates receiving a Biologics License Application (BLA) from the U.S. FDA for OST-HER2 in osteosarcoma in 2026 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. The Company also anticipates receiving Conditional Marketing Authorisations from the U.K.'s Medicines and Healthcare products Regulatory Agency and the EMA for OST-HER2 in 2026. 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. The Company also anticipates reading out data from a Phase 1b study of OST-504 in castration resistant prostate cancer in the first half of 2026.
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 our expected to provide cash runway into 2027, the intended use of net proceeds from the offering, the potential 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 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
Stephanie Chen
Elev8 New Media
media@ostherapies.com
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To view the source version of this press release, please visit https://www.newsfilecorp.com/release/299365