OS Therapies Completes Requalification of Phase 2b Herlystic (OST-HER2) Drug Substance for Confirmatory Phase 3 Trial

(NYSE/NASDAQ:OSTX) OS Therapies, Inc. announced the completion of requalification of the drug substance used in its Phase 2b trial of OST-HER2 (Herlystic™) for the prevention of recurrence in fully resected, pulmonary metastatic osteosarcoma. This requalification enables the company to begin submission of a Conditional Marketing Authorisation Application (CMAA) and complete a Rolling Review Request for Herlystic (Daznelimgene Lisbac) to the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) for early commercial market access, as well as file the Clinical Trial Authorisation (CTA) required to initiate the confirmatory Phase 3 trial. OS Therapies will use the requalification data to support CMAA submissions to the European Medicines Agency (EMA) and to include in the U.S. Food and Drug Administration (FDA) Biologics License Application (BLA) submissions. The company has paused regulatory interactions in Australia to focus resources on the U.S., U.K., and Europe. Paul Romness, Chairman and CEO, stated that the stability data from the Phase 2b trial material shows the product and its Critical Quality Attributes (CQAs) remain stable after ten years in storage. The company reported that its recent capital raise and Refundable R&D Tax Credit and VAT programs provide sufficient resources to fund operations through mid-2027. Due to delays in receiving manufacturing data, OS Therapies now expects a regulatory decision on the pending MHRA CMAA in the first quarter of 2027 and from EMA in the first half of 2027. The company intends to update the market on the timing of completion of BLA activities and related regulatory interactions with the FDA after receiving additional feedback on comparator data for the Accelerated Approval Program. Additional sources of data for OST-400 are being evaluated for inclusion in submissions to the FDA. OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD), and Rare Pediatric Disease Designation (RPDD) from the FDA, as well as ODD and Advanced Therapeutic Medicinal Product (ATMP) designation from the EMA. OST-HER2 was granted access to the Centralised Procedure in Europe, allowing for a unified, expedited regulatory review process. Under the RPDD program, if granted a BLA in the U.S., the company would become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. Two recent PRV sales in October 2026 totaled $413 million, with an average of $206.5 million per voucher, though there is no assurance OS Therapies would realize a comparable value. The company has completed resubmission of a Regenerative Medicine Advanced Therapy (RMAT) request and is awaiting FDA feedback. Its Commissioner's National Priority Voucher (CNPV) letter of intent was accepted by the FDA in the first quarter of 2026. OS Therapies intends to complete its BLA submission under the Accelerated Approval Program in the U.S. and CMAAs in Europe and the U.K. for OST-HER2 in metastatic osteosarcoma in the fourth quarter of 2026. OST-HER2 has completed a Phase 1 clinical study in breast cancer patients and showed preclinical efficacy in various breast cancer models. OST-HER2 was previously conditionally approved by the U.S. Department of Agriculture for treating canines with osteosarcoma. The company has completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer. OS Therapies is also advancing its next-generation Antibody Drug Conjugate (ADC) and Drug Conjugates (DC), known as tunable ADC (tADC), which uses proprietary silicon Si-Linker and Conditionally Active Payload (CAP) technology to deliver multiple payloads per linker.

OS Therapies Announces Initial Closing of Warrant Exercise Inducement and Exchange Offer for Initial Gross Proceeds of Approximately $7.2 Million

(NYSE:OSTX) OS Therapies Inc. announced the initial closing of a warrant exercise inducement and exchange offer made to nine accredited investors who owned common stock purchase warrants. Seven of these investors exercised or pre-funded the exercise of Existing Warrants to purchase an aggregate of 5,517,253 shares of common stock at a reduced exercise price of $1.30 per share (or $1.299 per share for pre-funding), resulting in $7.2 million in gross proceeds to the company before fees and expenses. Most of the Existing Warrants exercised or pre-funded had an original exercise price of $1.40 per share. In exchange, the company issued new common stock purchase warrants to the participating holders to purchase up to 5,517,253 shares at an exercise price of $1.40 per share. The offer is scheduled to expire at 11:59 p.m. Eastern time on October 30, 2026, unless extended or terminated earlier, and is only available to the specified holders. OS Therapies has also accrued $7 million in refundable research and development tax credits through its U.K. subsidiary, with the tax credit filing expected to be submitted in Q4 2026 and receipt anticipated in early 2027. The company expects to use the net proceeds to support regulatory filings and commercial preparation activities for Herlystic™ in the prevention or delay of recurrence in fully resected, pulmonary metastatic osteosarcoma in the U.S., U.K., European Union, and Australia, as well as for general corporate purposes. Chair & CEO Paul Romness stated that the proceeds will provide capital to advance Herlystic™ early market access submissions with regulators in the U.S., U.K., Europe, and Australia. The company intends to submit a Biologics License Application (BLA) to the U.S. FDA under the Accelerated Approval Program and Conditional Marketing Authorisation Applications (CMAAs) to the U.K. MHRA, EMA, and Australian TGA in Q4 2026. Herlystic™ has received Orphan Drug Designation (ODD), Fast Track Designation (FTD), and Rare Pediatric Disease Designation (RPDD) from the FDA, as well as ODD, PRIME, and ATMP from the EMA. Under the RPDD program, if the BLA is approved, the company may become eligible to receive a Priority Review Voucher (PRV), which it intends to sell; the most recent PRV sale occurred in October 2026 for $203 million. OS Therapies has completed resubmission of a Regenerative Medicine Advanced Therapy (RMAT) designation request and its Commissioner's National Priority Voucher (CNPV) letter of intent has been accepted by the FDA. Herlystic™ has completed a Phase 2b clinical trial in osteosarcoma, demonstrating clinically significant benefit in the 12-month event free survival (EFS) primary endpoint and overall survival (OS) secondary endpoint. The company has also completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer and is advancing its tunable ADC (tADC) platform, which leverages proprietary silicon Si-Linker and Conditionally Active Payload (CAP) technology. Herlystic™ was previously conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma.

OS Therapies Announces Brand Name 'Herlystic' Approved by World Health Organization for OST-HER2 (daznelimgene lisbac)

(NYSE American: OSTX) OS Therapies, Inc. announced that the World Health Organization (WHO) has approved 'Herlystic'™ as the proprietary brand name for OST-HER2, and previously approved 'daznelimgene lisbac' as the nonproprietary name for the ingredients in OST-HER2. With both names now approved, OS Therapies is positioned to initiate regulatory submissions for early market access for OST-HER2 worldwide. The company intends to begin international regulatory submissions in the U.K. at the invitation of the Medicines and Healthcare products Regulatory Agency (MHRA), followed by submissions to the U.S. Food & Drug Administration (FDA), the European Medicines Agency (EMA), and the Australian Therapeutic Goods Administration (TGA). MHRA will act as the lead international regulatory agency under Project Orbis, an FDA Oncology Center of Excellence initiative for concurrent submission and review of oncology products among international partners. Since 2021, 29 MHRA-led oncology products have been approved by the FDA under Project Orbis. Paul Romness, MPH, Chairman & CEO of OS Therapies, stated that the company is moving ahead with early market access regulatory filings, with MHRA's submission slated in the coming weeks based on 2.5-year and interim 3-year Overall Survival (OS) data, and subsequent submissions to FDA, EMA, and TGA once final 3-year OS data is available. MHRA, EMA, and TGA have agreed to use non-concurrent historical control to evaluate efficacy for OST-HER2's pending Conditional Marketing Authorization Application (CMAA) submissions, while the FDA uses surrogate clinical endpoints such as biomarkers for Biologics License Applications (BLAs) under the Accelerated Approval Program. OS Therapies is awaiting completion of 3-year OS data for a pending meeting with the Center for Drug Research Evaluation (CDER) to review the correlation between pharmacodynamic response biomarkers and overall survival as part of the Biomarker Qualification Program. The previously announced Type B Pre-BLA Meeting will occur once the full data package is complete, while BLA submission, initiated in January 2026, continues. The company expects to have sufficient additional concurrent external historical control comparator data via the Clinical Practice Research Datalink (CPRD) to support its BLA filing. OST-HER2 has received Orphan Drug Designation (ODD), Fast Track Designation (FTD), and Rare Pediatric Disease Designation (RPDD) from the FDA; ODD, FTD, and Advanced Therapy Medicinal Products (ATMP) from the EMA; and ODD and ATMP from MHRA, which also recruited the company into Project Orbis. Under the RPDD program, if granted a BLA in the United States, OS Therapies will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. A recent PRV sale in August 2026 occurred for $220 million, though there is no assurance the company would realize a comparable value in any future PRV sale. OS Therapies has completed resubmission of a Regenerative Medicine Advanced Therapy (RMAT) request and its Commissioner's National Priority Review Voucher (CNPV) letter of intent has been accepted by the FDA. The company is seeking a Conditional Marketing Authorization Application from MHRA in the U.K. under Project Orbis for OST-HER2 in metastatic osteosarcoma in the fourth quarter of 2026, and immediately thereafter is seeking to obtain a BLA under the Accelerated Approval Program in the U.S., followed by CMAAs in Europe and Australia. OST-HER2 is the company's lead asset, an immunotherapy leveraging Listeria bacteria to target the HER2 protein, and has demonstrated clinically significant benefit in a Phase 2b clinical trial for the 12-month event free survival (EFS) primary endpoint and overall survival (OS) secondary endpoint in pulmonary metastatic osteosarcoma. OST-HER2 has completed a Phase 1 clinical study in breast cancer patients and shown preclinical efficacy in various breast cancer models. OST-HER2 was previously conditionally approved by the U.S. Department of Agriculture for treating canines with osteosarcoma. The company has completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer. OS Therapies is also advancing next-generation Antibody Drug Conjugate (ADC) and Drug Conjugates (DC), known as tunable ADC (tADC), featuring proprietary silicon Si-Linker and Conditionally Active Payload (CAP) technology.

OS Therapies Inc: Termination of a Material Definitive Agreement

(NYSE/NASDAQ:OSTX) The company announced the termination of a material definitive agreement.