OS Therapies Provides First Half 2026 Corporate Outlook

Rhea-AI Summary

OS Therapies (NYSE: OSTX) outlined a H1 2026 corporate outlook focused on regulatory submissions and clinical readouts. The company plans a U.S. BLA filing for OST-HER2 under Accelerated Approval by end of January 2026, with UK and EU MAA submissions expected by end of February and March 2026. Phase 2b biomarker data from the metastatic osteosarcoma program is expected the week of the J.P. Morgan Healthcare Conference 2026. The company expects multiple regulator meetings in H1 2026 and provisional approval timing of UK Q2, US Q3, EU Q4 2026. OS Animal Health confidential SEC filing expected early January 2026. OST-504 data delayed to Q1 2026; End of Phase meetings for OST-504 and OST-503 expected in Q2 2026.

Positive

• U.S. BLA filing for OST-HER2 planned by end of January 2026
• UK MAA submission expected by end of February 2026
• EU MAA submission expected by end of March 2026
• Phase 2b biomarker data due week of J.P. Morgan Healthcare Conference 2026
• Projected regulatory approvals: UK Q2, US Q3, EU Q4 2026
• OS Animal Health confidential SEC filing expected early January 2026

Negative

• OST-504 Phase 1 clinical data delayed to Q1 2026
• OST-HER2 approval contingent on Accelerated Approval and confirmatory trials
• Projected approval timing is tentative and may be delayed

Key Figures

BLA filing target end of January 2026 Planned U.S. FDA Biologics License Application for OST-HER2

UK MAA target end of February 2026 Planned MHRA Marketing Authorisation Application submission

EU MAA target March 2026 Planned EMA conditional approval submission for OST-HER2

PRV eligibility deadline September 30, 2026 Must receive Accelerated Approval before this date to earn PRV

Recent PRV sale $160 million Value of most recent Priority Review Voucher sale in June 2025

OST-504 End-of-Phase 1 Q2 2026 Expected FDA meeting after delayed Phase 1 prostate cancer data

OST-503 End-of-Phase 2 Q2 2026 Planned FDA meeting on NSCLC frontline trial with Keytruda

Animal Health SEC filing early January 2026 Expected confidential go‑public filing for OS Animal Health

Market Reality Check

$1.55 Last Close

Volume Volume 472,657 is slightly below the 498,516 share 20-day average. normal

Technical Shares at $1.34 are trading below the $1.81 200-day moving average and 80.86% below the 52-week high.

Peers on Argus

OSTX fell 4.29% while close biotech peers were mixed: ANL -2.82%, BYSI -3.01%, IMMX +3.23%, ACET +4.63%, ATHE -0.94%, pointing to stock‑specific pressure rather than a broad sector move.

Historical Context

Date	Event	Sentiment	Move	Catalyst
Dec 15	FDA Type C meeting	Positive	-7.7%	FDA confirmed single‑arm data could support BLA via Accelerated Approval.
Dec 09	UK MHRA interaction	Positive	+0.0%	Pre‑MAA meeting achieved alignment on CMC and confirmatory study design.
Dec 05	Regulatory update	Positive	+5.5%	FDA BLA fee waiver and EMA Union Marketing Authorisation eligibility granted.
Nov 25	INN naming	Positive	+4.7%	WHO approved the INN ‘daznelimgene lisbac’ for OST‑HER2 program.
Nov 21	Analyst coverage	Positive	+5.6%	Update highlighted strong Phase 2b survival data and 1H26 Animal Health spinoff.

Pattern Detected

Recent OST-HER2 regulatory and clinical milestones were generally positive, with three events followed by gains and two by flat or negative reactions, suggesting inconsistent pricing of good news.

Recent Company History

Over the last few months, OS Therapies has steadily advanced OST-HER2 toward potential approvals. A Nov 21, 2025 update highlighted strong Phase 2b survival data and financing runway. Subsequent November and December releases detailed WHO naming, EMA Union Marketing Authorisation eligibility, and successful UK MHRA and FDA meetings, all supporting BLA and MAA filings targeted for early 2026. Market reactions alternated between gains and a notable -7.73% drop, so today’s first‑half 2026 regulatory roadmap continues a pattern of incremental progress not always reflected in near‑term trading.

Regulatory & Risk Context

Active S-3 Shelf Registration 2025-08-08

$100,000,000 registered capacity

An effective S-3 shelf filed on Aug 8, 2025 allows OS Therapies to offer up to $100,000,000 of securities and includes an at‑the‑market prospectus for up to $18,000,000 of common stock. Two prospectus supplements (forms 424B5 and 424B7) were filed in Aug and Sep 2025, indicating the company has begun using this capital‑raising capacity alongside its ongoing clinical and regulatory plans.

Market Pulse Summary

The stock moved +7.5% in the session following this news. A strong positive reaction aligns with a steady build‑out of OST‑HER2’s regulatory pathway, including BLA and MAA timelines through Q1 2026 and potential Priority Review Voucher eligibility before September 30, 2026. Past news produced mixed price responses, with some positive regulatory milestones followed by gains and others by a -7.73% decline. Investors would have weighed remaining execution risks around confirmatory trials, funding capacity under the $100,000,000 shelf, and delivery of biomarker and Phase 1/2 data as key factors for sustaining momentum.

Key Terms

biologics license application (bla) regulatory

"preparations for end of January 2026 U.S. FDA Biologics License Application (BLA) submission"

A biologics license application (BLA) is a formal request to a government agency seeking approval to sell a biological medicine, such as vaccines or gene therapies, in the market. It is similar to a detailed report that proves the product is safe, effective, and manufactured properly. For investors, a BLA signifies a critical step toward commercial availability, often impacting a company's valuation and market prospects.

accelerated approval program regulatory

"Metastatic Osteosarcoma Program under Accelerated Approval Program"

A regulatory pathway that lets a drug or treatment reach the market sooner for serious or life‑threatening conditions based on early signs of benefit (such as lab tests or short‑term results) rather than long‑term proof. It matters to investors because it can accelerate revenue and competitive advantage but carries higher risk: the approval depends on follow‑up studies, and if those fail regulators can withdraw the approval, which can sharply affect a company’s value.

marketing authorisation application (maa) regulatory

"UK and EU Marketing Authorisation Application (MAA) submissions for conditional approval"

An marketing authorisation application is a formal request submitted to a health regulator asking for permission to sell a new medicine or medical product in a given market. For investors it matters because approval is the regulatory ‘green light’ that allows commercial sales and revenue, while delays, additional requirements, or rejection create uncertainty about timing, costs and a product’s market potential.

orphan disease designation regulatory

"OST-HER2 has received Orphan Disease Designation (ODD) and Fast Track Designation"

A regulatory label granted to a drug or treatment aimed at a rare medical condition, recognizing that few patients need it. It brings incentives such as reduced development costs, regulatory help and a period of protection from direct competition — like a government badge and temporary shield for a small-market product. For investors, the designation can lower risk, speed approval and raise the potential commercial value of a therapy.

fast track designation regulatory

"Orphan Disease Designation (ODD) and Fast Track Designation from the FDA and EMA"

A "fast track designation" is a process that speeds up the review and approval of a product or project, allowing it to reach the market or be completed more quickly than usual. For investors, it can signal that a product may become available sooner, potentially leading to earlier revenue or benefits, and indicating a priority status that might influence company performance and market opportunities.

rare pediatric disease designation regulatory

"has received Rare Pediatric Disease Designation (RPDD) from FDA"

A rare pediatric disease designation is an official regulatory status given to a drug or therapy that targets a serious or life‑threatening condition primarily affecting children and is uncommon in the population. It matters to investors because the status often brings financial and development perks — such as tax credits, reduced fees, faster review and periods of market protection — which can lower costs, speed approval and improve the commercial outlook; think of it as a VIP pass that makes bringing a scarce, child‑focused treatment to market easier and potentially more profitable.

priority review voucher regulatory

"it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell"

A priority review voucher is a transferable regulatory incentive that lets a company move a future drug or device application to the front of the review line, shortening the review period by several months. For investors it matters because the voucher can speed up market access for a high-value product or be sold to other companies for significant cash, acting like a tradable fast-pass that can accelerate revenue or create immediate financial upside.

go-public transaction financial

"OS Animal Health 'go-public' transaction SEC filing expected in early January 2026"

A go-public transaction is the process by which a privately held company begins selling its shares to the general public, commonly through an initial public offering, a direct listing, or by merging with a publicly listed vehicle. It matters to investors because it creates a new opportunity to buy equity, often changes how the business is funded and regulated, and typically increases both the company’s visibility and the scrutiny of its financial performance—like a family business opening a store for all customers instead of serving only known patrons.

AI-generated analysis. Not financial advice.

• Company finalizing preparations for end of January 2026 U.S. FDA Biologics License Application (BLA) submission for OST-HER2 program in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma (Metastatic Osteosarcoma Program) under Accelerated Approval Program
• Biomarker data from Phase 2b Metastatic Osteosarcoma Program human clinical trial expected to be released during week of J.P. Morgan Healthcare Conference 2026
• UK and EU Marketing Authorisation Application (MAA) submissions for conditional approval expected by end of February 2026 and March 2026, respectively
• Company expects to participate in multiple H1 2026 meetings with U.S. FDA, U.K. MHRA and Europe's EMA as part of processes to gain regulatory approvals
• OS Animal Health 'go-public' transaction SEC filing expected in early January 2026
• Delayed data from OST-504 Phase 1 trial in castration resistant prostate cancer expected in Q1 2026 after prioritizing biomarker lab partner resources for osteosarcoma data analysis, with End of Phase 1 FDA meeting expected in Q2 2026
• Company plans to request End of Phase 2 meeting with FDA to review OST-503 non-small cell lung cancer frontline trial results in combination with Keytruda®

New York, New York--(Newsfile Corp. - January 5, 2026) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, today provided stakeholders with a corporate outlook for the first half 2026.

The outlook highlights planned submissions to seek regulatory approval for the Company's lead candidate OST-HER2 in the U.S., U.K. and Europe, the expected release of Phase 2b biomarker data from the Company's Metastatic Osteosarcoma Program in the first half of January 2026, as well as additional pipeline and corporate milestones.

"OS Therapies is potentially at the cusp of improving the standard of care for patients with metastatic osteosarcoma," said Chairman & CEO Paul Romness. "2025 was a transformational year in which we announced promising OST-HER2 clinical trial results and had significant interactions with regulatory agencies in the U.S., U.K. and Europe regarding the path toward conditional marketing authorizations in 2026. We have incorporated the guidance received from those meetings into a clear regulatory plan that aligns our strategy with each regulatory agency's specific feedback."

Mr. Romness added, "In parallel, with much of the work related to OST-HER2 regulatory submissions winding down in the second half of Q1 2026, we expect to start making regulatory progress in our human OST-503 and OST-504 programs. We also look forward to completing a go-public transaction for our OS Animal Health subsidiary in the first half of 2026, with a confidential filing with the SEC expected in the very near future."

The Company expects to release biomarker data from its Phase 2b human clinical trial of OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma during the week of the J.P. Morgan Healthcare Conference 2026.

The Company reiterates its intention to file a BLA with the U.S. FDA under the Accelerated Approval Program (Accelerated Approval) by the end of January 2026. The Company intends to complete MAA submissions seeking conditional marketing authorization with the U.K. MHRA and Europe's EMA by end of February 2026 and March 2026, respectively.
Following these submissions, the Company expects to engage in multiple meetings with regulatory authorities in the U.S., U.K., and Europe during the first half of 2026. These discussions are expected to address proposed surrogate clinical efficacy endpoints, confirmatory trial design, and post-market authorization monitoring plans in support of regulatory review. Following these additional meetings requested by the FDA, MHRA and EMA, the Company anticipates the potential to receive regulatory approval for OST-HER2 in the U.K. in Q2 2026, in the United States in Q3 2026 and in Europe by the end of Q4 2026.

OST-HER2 has received Orphan Disease Designation (ODD) and Fast Track Designation from the FDA and EMA, and has received Rare Pediatric Disease Designation (RPDD) from FDA. Under the RPDD program, if the Company receives Accelerated Approval prior to September 30, 2026, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The most recent PRV sale valued at $160 million occurred in June 2025.

The Company expects to advance a go-public transaction for its OS Animal Health subsidiary, with a confidential filing with the U.S. Securities and Exchange Commission expected in early January 2026. OS Animal Health is seeking to gain regulatory approval for OST-HER2 from the United States Department of Agriculture (USDA) for the treatment of pulmonary metastatic osteosarcoma, as well as frontline osteosarcoma. OST-HER2 was featured in the Emmy-nominated documentary 'Shelter Me: Cancer Pioneers' streaming on PBS.

Beyond OST-HER2, the Company expects to advance additional human oncology programs. The Company expects delayed data from its OST-504 Phase 1 trial in castration resistant prostate cancer in the first quarter of 2026 after prioritizing biomarker lab partner resources for osteosarcoma data analysis, with an End of Phase 1 meeting with the FDA expected in Q2 2026. The Company also expects an End of Phase 2 meeting with the FDA in the Q2 2026 to review OST-503 non-small cell lung cancer frontline trial results in combination with Keytruda®.

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 listeria-based cancer immunotherapies. OST-HER2, the Company's lead asset, is an immunotherapy designed to leverage the immune-stimulatory effects of Listeria bacteria to generate a strong immune response targeting the HER2 protein. OST-HER2 has received Rare Pediatric Disease Designation from the U.S. Food & Drug Administration and has also received Fast Track and orphan drug designations from the U.S. FDA and European Medicines Agency in Europe. The Company reported positive data in its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, lung metastatic osteosarcoma, demonstrating a statistically significant benefit in the study's primary endpoint of 12-month event free survival (EFS) primary endpoint of the study as well as 2-year overall survival data, the study's secondary endpoint. The Company anticipates submitting a Biologics License Application (BLA) to the U.S. FDA for OST-HER2 in osteosarcoma in 2026 and, if approved prior to September 30, 2026, would become eligible to receive a Priority Review Voucher that it intends to sell. OST-HER2 has also completed a Phase 1 clinical study primarily in breast cancer patients and has demonstrated preclinical efficacy in multiple models of breast cancer. In veterinary oncology, OST-HER2 has been conditionally approved by the U.S. Department of Agriculture for the treatment of canines with osteosarcoma.

In addition, OS Therapies is advancing its next-generation Antibody Drug Conjugate (ADC) and Drug Conjugates (DC) platform, known as its tunable ADC (tADC) platform, which is designed to create tunable antibody-linker-payload candidates. This platform leverages the Company's proprietary Si-Linker and Conditionally Active Payload (CAP) technology designed to enable 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 the 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, most recent Quarterly Report on Form 10-Q 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/

To view the source version of this press release, please visit https://www.newsfilecorp.com/release/279451

FAQ

When will OS Therapies (OSTX) file the U.S. BLA for OST-HER2?

The company intends to file a U.S. BLA under Accelerated Approval by end of January 2026.

When will OS Therapies (OSTX) release Phase 2b OST-HER2 biomarker data?

Biomarker data is expected during the week of the J.P. Morgan Healthcare Conference 2026.

What is the expected timing for UK, US and EU approvals for OST-HER2 (OSTX)?

Company anticipates potential approvals in the UK Q2 2026, US Q3 2026, and EU by Q4 2026.

Is OS Therapies (OSTX) pursuing a public offering for OS Animal Health?

Yes; a confidential SEC filing for OS Animal Health is expected early January 2026 to advance a go-public transaction.

Why was OST-504 data delayed for OS Therapies (OSTX)?

OST-504 data was delayed to Q1 2026 after prioritizing biomarker lab resources for osteosarcoma data analysis.

Could OS Therapies (OSTX) receive a Priority Review Voucher (PRV)?

If OST-HER2 receives Accelerated Approval before September 30, 2026, the company would be eligible for a PRV.