OS Therapies Files New Patent Application Covering Biomarkers of the Immune Response to Listeria Monocytogenes
Rhea-AI Summary
OS Therapies (NYSE American: OSTX) filed a patent application covering a treatment-emergent immune signature tied to Listeria-based OST-HER2 therapy in its Phase 2b trial for preventing or delaying recurrent, fully‑resected pulmonary metastatic osteosarcoma.
The company says the biomarker met FDA BEST pharmacodynamic/response criteria as a surrogate for 1‑year event‑free survival and 2‑year overall survival, will host an April 2026 call, will file to EMA on April 30, 2026, and aims for a BLA under Accelerated Approval in H2‑2026.
Positive
- Patent application filed covering OST-HER2 immune biomarker signature
- Biomarker correlates with 1‑year EFS and 2‑year overall survival
- EMA market‑access filing scheduled for April 30, 2026
- Company pursuing BLA under FDA Accelerated Approval in H2‑2026
- OST-HER2 holds FDA ODD, FTD and RPDD designations
Negative
- Biomarker correlation reported from Phase 2b; broader validation not disclosed
- Regulatory approvals still pending across FDA, EMA, MHRA and TGA
- Reliance on Accelerated Approval may require confirmatory trials post‑approval
News Market Reaction – OSTX
In the Apr 16 session, OSTX gained 1.45%, reflecting a mild positive market reaction.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Historical Context
| Date | Event | Sentiment | 24h Move | Catalyst |
|---|---|---|---|---|
| Apr 13 | Strategic advisor hire | Positive | +1.5% | Biotech luminary Robert Langer joins as strategic advisor for listeria pipeline. |
| Apr 08 | Strategic advisor hire | Positive | +1.6% | Craig Eagle appointed to advise on osteosarcoma regulatory execution and pipeline. |
| Apr 02 | Registered direct offering | Negative | -6.6% | Completed $5.25M registered direct equity offering with warrants. |
| Mar 31 | Earnings & clinical update | Positive | +6.0% | Filed Phase 2b data for FDA Pre-BLA and reported 2025 financial results. |
| Mar 27 | Regulatory meetings | Positive | +2.9% | Secured multi-agency meetings for global confirmatory Phase 3 trial design. |
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Over the past month, OSTX has generally traded up on strategic, clinical, and regulatory progress, while capital-raising (registered direct) coincided with a notable one-day decline.
In the last few weeks, OSTX has reported multiple regulatory and clinical milestones for OST-HER2, including global agency meetings, Phase 2b data submissions, and progress toward a potential BLA and CMAs in 2H/26. Strategic advisor appointments on Apr 8 and Apr 13 coincided with modest gains. In contrast, the $5.25M registered direct offering on Apr 2 saw a negative reaction. Today’s biomarker-focused patent news extends the same OST-HER2 and accelerated-approval narrative.
Key Terms
biomarker medical
pharmacodynamic medical
surrogate clinical endpoint medical
event free survival medical
overall survival medical
biologics license application regulatory
accelerated approval program regulatory
priority review voucher regulatory
AI-generated analysis. How Rhea-AI works. Not financial advice.
- New patent application covers treatment-emergent immune signature related to 'turning cold tumors hot' and the activation of targeted cytotoxic cellular immune responses
- Company to host conference call later in April 2026 to review new biomarker signature
- Biomarker signature meets pharmacodynamic/response criteria established by FDA's Biomarkers, EndpointS and other Tools (BEST) program for use as a surrogate clinical endpoint of 1-year event free survival and 2-year overall survival in OST-HER2's Phase 2b trial in the prevention of delay of recurrent, fully-resected, pulmonary metastatic osteosarcoma to support a BLA submission under FDA's Accelerated Approval Program
New York, New York--(Newsfile Corp. - April 16, 2026) - OS Therapies, Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in gene-edited, listeria-based cancer immunotherapies, today announced that it has filed a new patent application covering a unique immune signature in response to treatment with therapeutic candidates developed from the Company's proprietary Listeria monocytogenes platform ('Listeria') based on new biomarker data from the Company's Phase 2b trial of OST-HER2 in the prevention or delay of recurrent, fully-resected, pulmonary metastatic osteosarcoma. Filed claims include treatment with Listeria leading to the downregulation of genes associated with tumor and circulating tumor cell immune evasion in combination with the upregulation of genes associated with cytotoxic cellular immune activation leads to improved anti-tumor cellular immunity activation. The Company will host a conference call later in April 2026 to review OST-HER2 Phase 2b's new treatment response biomarker signature data showing correlation with clinical outcomes, and its regulatory implications in upcoming Q2-2026 meetings and regulatory submissions with the U.S. Food & Drug Administration (FDA), the European Medicines Agency (EMA), the U.K. Medicines and Healthcare products Regulatory Agency (MHRA) and the Australian Therapeutic Goods Administration (TGA). The Company will complete the first complete OST-HER2 regulatory market access filing in the world to the EMA, at its request, on April 30, 2026.
"The biomarker data from patients who responded to OST-HER2 treatment shows tremendous innate and adaptive immune responses that result in a significantly improved ability to fight cancer," said Paul Romness, MPH, Chair & CEO of OS Therapies. "While not all metastatic osteosarcoma is HER2 positive, a recently published study reported that over
Mr. Romness continued, "Notwithstanding the potential for future indication expansion, we are now laser focused on our packed Q2-2026 regulatory meeting schedule with FDA, EMA, MHRA and TGA in preparation for gaining accelerated market access for OST-HER2 in the fully-resected pulmonary metastatic setting later this year in the U.S., Europe and the U.K. with the potential to expand beyond these jurisdictions in 2027."
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 Biologics License Application (BLA) in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The most recent publicly disclosed PRV transaction occurred in February 2026 at a reported value of
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 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 statistically 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
https://x.com/OSTherapies
https://www.instagram.com/ostherapies/
https://www.facebook.com/OSTherapies/
https://www.linkedin.com/company/os-therapies/
[1] https://ascopubs.org/doi/10.1200/OA-25-00094
[2] https://www.fda.gov/drugs/biomarker-qualification-program/about-biomarkers-and-qualification
[3] https://www.fda.gov/drugs/nda-and-bla-approvals/accelerated-approval-program
To view the source version of this press release, please visit https://www.newsfilecorp.com/release/292852