OS Therapies Completes Requalification of Phase 2b Herlystic (OST-HER2) Drug Substance for Confirmatory Phase 3 Trial
Manufacturing-data delays pushed expected U.K. and European regulatory decisions into 2027.
Sentiment and the balance of points
Rhea-AI Sentiment reads the wording of the document, how positive or negative its language is on a 1 to 5 scale. The balance of points shown with the takes weighs what the document actually discloses, so the two can disagree, for example when a trial that missed its main goal is described in upbeat language.
Rhea-AI Summary
OS Therapies (OSTX) completed requalification of the drug substance used in its Phase 2b Herlystic trial, advancing preparations for confirmatory Phase 3 testing.
The milestone enables U.K. conditional marketing and trial-authorisation filings and will support European and U.S. submissions. The company said the material remained stable after ten years in storage. Manufacturing-partner data delays shifted expected regulatory decisions to first-quarter 2027 in the U.K. and first-half 2027 in Europe. U.S. filing timing will be updated after further FDA feedback on comparator data. OS Therapies intends to complete U.K. and European applications in fourth-quarter 2026.
The company expects its recent capital raise and refundable research tax-credit and VAT programs to fund operations through mid-2027. Australian regulatory interactions are paused to concentrate resources on the U.S., U.K. and Europe.
How this balance works
Rhea-AI gives every point it takes from this document a weight. Minor counts 1, Moderate 3 and Major 9, so one Major point outweighs several Minor ones. The bar adds up the weights on each side, and when neither side holds more than 65% of the total the balance reads Mixed.
It reads the document as published, with the same rules for every company, and it does not look at what the market expected or at how the stock traded, so a point can be objectively good on a day the stock falls.
Rhea-AI Sentiment measures something else, the tone of the wording.
Hollow bars mark forward-looking points. How the balance works
Positive
- Moderate pointDrug-substance requalification completed, enabling U.K. marketing and Phase 3 trial-authorisation filings and supporting European and U.S. submissions.
- Moderate point. Forward-looking: it has not happened yet and may not happen.Operations funded through mid-2027, the company expects, using its recent raise and refundable tax-credit and VAT programs.
- Moderate point. Forward-looking: it has not happened yet and may not happen.U.K. and European conditional marketing applications are targeted for completion in fourth-quarter 2026.
- Minor pointTen-year storage stability was demonstrated for the Phase 2b material and its critical quality attributes, the company said.
- Minor pointEuropean Centralised Procedure access permits a unified review rather than separate applications in individual EU member states.
4 minor points
- Minor pointFDA designations include Orphan Drug, Fast Track and Rare Pediatric Disease status for OST-HER2.
- Minor pointEMA designations include Orphan Drug and Advanced Therapeutic Medicinal Product status.
- Minor point. Forward-looking: it has not happened yet and may not happen.Priority Review Voucher eligibility would follow U.S. approval; the company intends to sell any voucher received.
- Minor pointCommissioner's National Priority Voucher letter of intent was accepted by FDA in first-quarter 2026.
Negative
- Moderate point. Forward-looking: it has not happened yet and may not happen.Manufacturing-partner data delays shifted expected U.K. decisions to first-quarter 2027 and European decisions to first-half 2027.
- Moderate pointU.S. filing-timing update awaits further FDA feedback on comparator data supporting accelerated approval.
- Minor pointPhase 3 initiation requires U.K. Clinical Trial Authorisation.
- Minor pointAustralian regulatory interactions paused as resources focus on the U.S., U.K. and Europe.
- Minor pointRegenerative Medicine Advanced Therapy request has been resubmitted, with FDA feedback still pending.
AI-generated analysis. How Rhea-AI works. Not financial advice.
Leading Clinical Stage Oncology Company Now Able to Complete CMMA Submission to U.K's MHRA for Early Commercial Access and Trial Authorisation
Grasonville, Maryland--(Newsfile Corp. - November 5, 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 completed the requalification of drug substance used in its Phase 2b trial of OST-HER2 (Herlystic™) in the prevention of recurrence in fully resected, pulmonary metastatic osteosarcoma. The requalification is key as the Company is now able to commence the 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 and file the Clinical Trial Authorisation (CTA) required to initiate the confirmatory Phase 3 trial.
Additionally, OS Therapies will be using the drug substance requalification data to support CMAA submissions to the European Medicines Agency (EMA), as well as to include in the U.S. Food and Drug Administration (FDA) Biologics License Application (BLA) submissions. The Company has decided to pause regulatory interactions in Australia to focus its resources on the U.S., U.K. and Europe.
"We are very pleased with the stability data generated from the material used in the Phase 2b trial, as it shows our product and its Critical Quality Attributes (CQAs) is stable even after ten years in storage," said Paul Romness, Chairman and CEO of OS Therapies. "With this important chemistry, manufacturing and controls (CMC) milestone now in-hand, we are moving full steam ahead on all regulatory fronts in the U.S., U.K., and Europe. We also note that our recent capital raise and Refundable R&D Tax Credit and VAT programs provides the Company with sufficient resources to fund operations through mid-2027."
Mr. Romness continued, "Due to the delay we experienced in receiving the data from our manufacturing partners to support the drug substance requalification to initiate the confirmatory Phase 3 program, we are updating our previously stated timelines to expect a regulatory decision on the pending MHRA CMAA in the first quarter of 2027, and from EMA in the first half of 2027. With respect to FDA, the Company intends to update the market on the timing of completion BLA activities, and regulatory interactions related thereto, following additional feedback on comparator data being assembled to support a BLA under the Accelerated Approval Program. The Company has identified additional sources of data for OST-400 that are currently being evaluated for inclusion in submissions to the Agency"
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 permitted access to the Centralised Procedure in Europe, allowing a unified, expedited regulatory review process rather than review of individual applications by each European Union (EU) Member State. Under the RPDD program, if the Company is granted a BLA in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. Two recent PRV sales occurred in October 2026, totaling
About OS Therapies
OS Therapies is a clinical stage oncology company focused on the identification, development, and commercialization of treatments for Osteosarcoma and other solid tumors. The Company is the world leader in gene-edited, 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, and Advanced Therapy Medicinal Products (ATMP) from the European Medicines Agency.
The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in the prevention or delay of recurrence in fully resected, pulmonary 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 intends to complete a Biologics License Application (BLA) submission to the U.S. FDA for OST-HER2 in osteosarcoma in the fourth quarter of 2026 and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. The Company also anticipates requesting Conditional Marketing Authorisation Applications (CMAAs) from the U.K.'s Medicines and Healthcare products Regulatory Agency (MHRA) and the European Medicines Agency (EMA)for OST-HER2 in the fourth quarter of 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 was previously conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma. The Company has also completed dosing in a Phase 1 study of OST-504 for castration-resistant prostate cancer.
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 silicon 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 regarding future expectations, plans, prospects or performance, as well as any other statements that are not historical facts, may constitute forward-looking statements within the meaning of the federal securities laws. Forward-looking statements are generally identified by words such as "anticipate," "believe," "could," "expect," "intend," "may," "plan," "potential," "should," "will" and similar expressions, although not all forward-looking statements contain these words. These statements are based on the current expectations and assumptions of OS Therapies and its management and are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such forward-looking statements. Such risks and uncertainties include, but are not limited to chemistry, manufacturing and controls (CMC) of OST-HER; OST-HER2 product stability; Company funding runway and need for additional capital; Commissioner's National Priority Voucher(CNPV) status, priority review voucher value, the timing and outcome of regulatory submissions and potential approval of OST-HER2 by the U.S. Food and Drug Administration and applicable foreign regulatory authorities; and other risks and uncertainties described under the heading "Risk Factors" in the Company's most recent Annual Report on Form 10-K and in its other filings with the Securities and Exchange Commission. The forward-looking statements contained in this press release speak only as of the date of this press release, and OS Therapies undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.
OS Therapies Contact Information:
INVESTOR CONTACT
Harrison Seidner, PhD
WaterSeid Partners
OSTX@waterseid.com
MEDIA CONTACT
James Lambert
Vice President
Rubenstein Public Relations
jlambert@rubensteinpr.com
212-805-3024
https://x.com/OSTherapies
https://www.instagram.com/ostherapies/
https://www.facebook.com/OSTherapies/
https://www.linkedin.com/company/os-therapies/
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To view the source version of this press release, please visit https://www.newsfilecorp.com/release/322651
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What did OS Therapies complete for Herlystic and its Phase 3 trial?
OS Therapies completed requalification of the drug substance used in its Phase 2b trial. This enables submission of the U.K. trial-authorisation application required to initiate confirmatory Phase 3 testing, alongside work on conditional marketing access.
When does OS Therapies expect U.K. and European decisions on Herlystic?
OS Therapies expects a U.K. regulatory decision in first-quarter 2027 and an EMA decision in first-half 2027. The revised expectations follow delays in receiving manufacturing-partner data needed for drug-substance requalification.
What could a Priority Review Voucher mean for OS Therapies?
OS Therapies would become eligible for a Priority Review Voucher if granted a U.S. Biologics License Application approval, and intends to sell it. Two October 2026 voucher sales totaled $413 million, averaging $206.5 million; comparable proceeds from any future company sale are not assured.
What additional data is OS Therapies evaluating for FDA submissions?
OS Therapies has identified additional sources of OST-400 data and is evaluating them for inclusion in FDA submissions. The company is also assembling comparator data to support a Biologics License Application under the Accelerated Approval Program.