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

<ul><li><i>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.</i></li></ul><p>New York, New York and Rockville, Maryland--(Newsfile Corp. - May 29, 2026) - <b>OS Therapies, Inc. (NYSE:<a class="ticker" href="https://www.benzinga.com/quote/OSTX">OSTX</a>) ("OS Therapies" or "the Company")</b>, 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.</p><ul><li><p><a href="https://api.newsfilecorp.com/redirect/24yX5c5vO1">Looking back to see forward: The future of osteosarcoma treatment<br /></a>Publication Date: December 8, 2025</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/MqeXJuMXoM">Comparative Oncology in Osteosarcoma: leveraging canine disease to drive drug discovery and validation of biomarkers and accelerate the pathway to new therapies<br /></a>Publication Date: February 23, 2026</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/bgvpEsazL0">Novel regulatory science considerations in osteosarcoma: the imperative for regulatory flexibility to meet critical unmet patient and clinical needs<br /></a>Publication Date: May 21, 2026</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/3KyD3SE5PN">The case for accelerated approval in recurrent osteosarcoma<br /></a>Publication Date: May 29, 2026</p></li></ul><p>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.</p><p>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.</p><p><b>About OS Therapies</b></p><p>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 &#38; Drug Administration and has received ODD, FTD and ATMP from the European Medicines Agency. </p><p>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.</p><p>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 <a href="https://api.newsfilecorp.com/redirect/N3MDGfNLE0">www.ostherapies.com</a>. </p><p><b>Forward-Looking Statements</b></p><p>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.</p><div id="contactInfo"><p><b>OS Therapies Contact Information:</b></p><p>Investor Relations<br />Harrison Seidner, PhD<br />WaterSeid Partners<br /><a href="mailto:OSTX@waterseid.com">OSTX@waterseid.com</a> </p><p>Public Relations<br />Stephanie Chen<br />Elev8 New Media<br /><a href="mailto:media@ostherapies.com">media@ostherapies.com</a> </p></div><p>     <a href="https://api.newsfilecorp.com/redirect/XEemwcP84X">https://x.com/OSTherapies</a><br /><a href="https://api.newsfilecorp.com/redirect/DOePNUn0Jx">https://www.instagram.com/ostherapies/</a><br /><a href="https://api.newsfilecorp.com/redirect/rpDQ3Hqbjg">https://www.facebook.com/OSTherapies/</a><br /><a href="https://api.newsfilecorp.com/redirect/VveGOsYGVo">https://www.linkedin.com/company/os-therapies/</a></p><p id="corporateNewsLogoContainer"><img src="https://images.newsfilecorp.com/files/11596/299365_a1615e6094986800_logo.jpg" id="corporateNewsLogo" alt="Corporate Logo" /></p><p id="corporateLinkBack">To view the source version of this press release, please visit <a href="https://api.newsfilecorp.com/redirect/zAGPgSy15X">https://www.newsfilecorp.com/release/299365</a></p><p><img src="https://api.newsfilecorp.com/newsinfo/299365/197" alt="" /></p>

OSTX

OS Therapies Announces the Publication of Four Articles on OST-HER2 and Osteosarcoma in Drug Discovery World

OSTX poised for near-term ASCO catalyst on OST-HER2 OS data

<section class="insight" data-version="1">
  <section data-block="information">
    <h3>Information</h3>
    <p>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</p>
  </section>

  <section data-block="ai-summary-paragraph">
    <h3>AI Summary</h3>
    <p>OS Therapies expects to release 2.5-year OS data for OST-HER2 at ASCO 2026, a potential near-term catalyst. The company targets a U.S. BLA under Accelerated Approval in 2H2026 and CMAs in Europe/UK/Australia, leveraging FDA/EMA designations that could accelerate access and unlock PRV value.</p>
  </section>

  <section data-block="ai-summary-bullets">
    <h3>Key Points</h3>
    <ul><li>OSTX to present OST-HER2 2.5-year OS data at ASCO 2026.</li><li>OST-HER2 holds FDA ODD/FTD/RPDD and EMA ODD/FTD/ATMP designations.</li><li>Phase 2b data showed 12-month EFS benefit and OS advantage.</li><li>US BLA planned 2H2026 with potential PRV sale; Europe/UK/Australia CMAs planned.</li></ul>
  </section>

  <section data-block="companies-mentioned">
    <h3>Companies Mentioned</h3>
    <ul><li><strong>OS Therapies, Inc. (OSTX)</strong>: Primary catalyst: 2.5-year OST-HER2 OS data at ASCO 2026; potential BLA/PRV timing.</li></ul>
  </section>

  <section data-block="category">
    <h3>Industry News</h3>
    <p>Industry News with corporate/regulatory development angle. The article highlights OSTX&#039;s OST-HER2 program milestones and regulatory designations, signaling near-term catalysts that can influence valuation and price action.</p>
  </section>

  <section data-block="market-moving">
    <h3>Market-Moving</h3>
    <ul><li>ASCO data readout timing (May 28–June 2, 2026) could trigger OSTX volatility.</li><li>Regulatory designations and accelerated approval path support upside valuation.</li><li>RPDD voucher sale may unlock additional cash runway.</li><li>OSTX faces data risk; competitive osteosarcoma landscape remains uncertain.</li></ul>
  </section>

  <section data-block="key-facts">
    <h3>Key Facts</h3>
    <ul><li>ASCO 2026 dates: May 28–June 2; OST-HER2 2.5-year OS data to be presented.</li><li>OST-HER2 has FDA ODD, FTD, RPDD; EMA ODD, FTD, ATMP designations.</li><li>US BLA planned 2H2026; potential Priority Review Voucher sale under RPDD.</li><li>Phase 2b OST-HER2: 12-month EFS primary endpoint achieved; OS secondary.</li><li>OST-504 Phase 1b data readout planned for 1H2026; cash runway into 2027.</li></ul>
  </section>

  <section data-block="trading-thesis">
    <h3>Trading Thesis</h3>
    <p>Near-term upside potential on positive OST-HER2 OS data at ASCO, with 2H2026 BLA/approval catalysts.</p>
  </section>
</section>


<ul><li><i>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.</i></li></ul><p>New York, New York and Rockville, Maryland--(Newsfile Corp. - May 29, 2026) - <b>OS Therapies, Inc. (NYSE:<a class="ticker" href="https://www.benzinga.com/quote/OSTX">OSTX</a>) ("OS Therapies" or "the Company")</b>, 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.</p><ul><li><p><a href="https://api.newsfilecorp.com/redirect/24yX5c5vO1">Looking back to see forward: The future of osteosarcoma treatment<br /></a>Publication Date: December 8, 2025</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/MqeXJuMXoM">Comparative Oncology in Osteosarcoma: leveraging canine disease to drive drug discovery and validation of biomarkers and accelerate the pathway to new therapies<br /></a>Publication Date: February 23, 2026</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/bgvpEsazL0">Novel regulatory science considerations in osteosarcoma: the imperative for regulatory flexibility to meet critical unmet patient and clinical needs<br /></a>Publication Date: May 21, 2026</p></li><li><p><a href="https://api.newsfilecorp.com/redirect/3KyD3SE5PN">The case for accelerated approval in recurrent osteosarcoma<br /></a>Publication Date: May 29, 2026</p></li></ul><p>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.</p><p>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.</p><p><b>About OS Therapies</b></p><p>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 &#38; Drug Administration and has received ODD, FTD and ATMP from the European Medicines Agency. </p><p>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.</p><p>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 <a href="https://api.newsfilecorp.com/redirect/N3MDGfNLE0">www.ostherapies.com</a>. </p><p><b>Forward-Looking Statements</b></p><p>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.</p><div id="contactInfo"><p><b>OS Therapies Contact Information:</b></p><p>Investor Relations<br />Harrison Seidner, PhD<br />WaterSeid Partners<br /><a href="mailto:OSTX@waterseid.com">OSTX@waterseid.com</a> </p><p>Public Relations<br />Stephanie Chen<br />Elev8 New Media<br /><a href="mailto:media@ostherapies.com">media@ostherapies.com</a> </p></div><p>     <a href="https://api.newsfilecorp.com/redirect/XEemwcP84X">https://x.com/OSTherapies</a><br /><a href="https://api.newsfilecorp.com/redirect/DOePNUn0Jx">https://www.instagram.com/ostherapies/</a><br /><a href="https://api.newsfilecorp.com/redirect/rpDQ3Hqbjg">https://www.facebook.com/OSTherapies/</a><br /><a href="https://api.newsfilecorp.com/redirect/VveGOsYGVo">https://www.linkedin.com/company/os-therapies/</a></p><p id="corporateNewsLogoContainer"><img src="https://images.newsfilecorp.com/files/11596/299365_a1615e6094986800_logo.jpg" id="corporateNewsLogo" alt="Corporate Logo" /></p><p id="corporateLinkBack">To view the source version of this press release, please visit <a href="https://api.newsfilecorp.com/redirect/zAGPgSy15X">https://www.newsfilecorp.com/release/299365</a></p><p><img src="https://api.newsfilecorp.com/newsinfo/299365/197" alt="" /></p>

OS Therapies expects to release 2.5-year OS data for OST-HER2 at ASCO 2026, a potential near-term catalyst. The company targets a U.S. BLA under Accelerated Approval in 2H2026 and CMAs in Europe/UK/Australia, leveraging FDA/EMA designations that could accelerate access and unlock PRV value.

OS Therapies Announces the Publication of Four Articles on OST-HER2 and Osteosarcoma in Drug Discovery World

AI Summary

Sentiment Rationale

Trading Thesis

Market-Moving

Key Facts

Companies Mentioned

Industry News

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