OS Therapies Applauds Reauthorization of Pediatric Priority Review Voucher Program to Advance Breakthrough Osteosarcoma Immunotherapies

Rhea-AI Summary

OS Therapies (NYSE American: OSTX) applauds reauthorization of the Rare Pediatric Disease Designation Priority Review Voucher program, extending PRV eligibility windows to September 30, 2026 through September 30, 2029. The change preserves potential PRV incentives for OST-HER2 and prompts re-evaluation of other listeria-based immunotherapy programs.

OST-HER2 holds FDA Orphan Disease Designation, FDA and EMA Fast Track, and FDA Rare Pediatric Disease Designation; a PRV would be available if Accelerated Approval is granted prior to September 30, 2029.

Positive

• PRV eligibility window extended to Sept 30, 2026–Sept 30, 2029
• OST-HER2 has FDA Orphan Disease Designation, FDA and EMA Fast Track, and FDA RPDD
• Reauthorization incentivizes re-evaluation of additional pipeline assets for PRV opportunities

Negative

• PRV eligibility is conditional on receiving Accelerated Approval before Sept 30, 2029
• Company has not disclosed timelines for BLA submissions or regulatory milestones

News Market Reaction

-5.67%

2 alerts

-5.67% News Effect

+4.3% Peak Tracked

-3.7% Trough Tracked

-$3M Valuation Impact

$47M Market Cap

0.9x Rel. Volume

On the day this news was published, OSTX declined 5.67%, reflecting a notable negative market reaction. Argus tracked a peak move of +4.3% during that session. Argus tracked a trough of -3.7% from its starting point during tracking. Our momentum scanner triggered 2 alerts that day, indicating moderate trading interest and price volatility. This price movement removed approximately $3M from the company's valuation, bringing the market cap to $47M at that time.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

PRV eligibility start: September 30, 2026 PRV eligibility extended: September 30, 2029

2 metrics

PRV eligibility start September 30, 2026 Original RPDD program cutoff date for PRV eligibility

PRV eligibility extended September 30, 2029 New deadline to obtain Accelerated Approval and receive PRV

Market Reality Check

Price: $1.20 Vol: Volume 366,060 is below t...

low vol

$1.20 Last Close

Volume Volume 366,060 is below the 20-day average of 709,591 (relative volume 0.52x). low

Technical Shares at $1.41 are trading below the $1.81 200-day moving average and 52.68% below the 52-week high of $2.98.

Peers on Argus

OSTX gained 1.44% while key biotech peers were mixed: ANL -8.29%, BYSI -3.21%, I...

1 Up

OSTX gained 1.44% while key biotech peers were mixed: ANL -8.29%, BYSI -3.21%, IMMX 2.42%, ACET -3.27%, ATHE -5.6%. Momentum scanner only flagged ANL (up 10.57%), indicating OSTX’s move was stock-specific rather than a sector-wide rotation.

Historical Context

5 past events · Latest: Feb 02 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Feb 02	BLA initiation	Positive	+2.2%	Started US BLA filing for OST-HER2 with rolling review request.
Jan 15	Clinical data update	Positive	-5.8%	Reported positive Phase 2b biomarker data and outlined global approval targets.
Jan 14	Subsidiary IPO plan	Positive	+0.7%	Filed S-1 for OS Animal Health IPO with planned share distribution.
Jan 12	Warrant financing	Positive	-7.1%	Raised $7.53M via warrant inducement to fund OST-HER2 and spinoff plans.
Jan 05	Corporate outlook	Positive	+7.5%	Outlined H1 2026 regulatory submissions and key clinical milestones.

Pattern Detected

Recent OSTX news often produced mixed reactions, with both strong gains and selloffs following generally positive regulatory and financing updates.

Recent Company History

In the last month, OS Therapies has focused on OST-HER2 regulatory progress and financing. On Jan 5, 2026, a detailed H1 2026 outlook drove a 7.46% gain. A $7.53M warrant inducement financing on Jan 12 saw a -7.1% reaction. Positive Phase 2b biomarker data on Jan 15 was followed by a -5.81% move, while the BLA initiation on Feb 2 aligned with a 2.21% rise. Today’s legislative PRV extension ties directly into this ongoing OST-HER2 approval path.

Regulatory & Risk Context

Active S-3 Shelf · $100,000,000

Shelf Active

Active S-3 Shelf Registration 2025-08-08

$100,000,000 registered capacity

An effective S-3 shelf filed on Aug 08, 2025 enables OS Therapies to issue up to $100,000,000 of securities, with an additional at-the-market prospectus supplement for up to $18,000,000 of common stock. The shelf has been used via 424B5 and 424B7 filings, indicating an established mechanism for future capital raises alongside today’s non-dilutive PRV-related legislative benefit.

Market Pulse Summary

The stock moved -5.7% in the session following this news. A negative reaction despite the extension ...

Analysis

The stock moved -5.7% in the session following this news. A negative reaction despite the extension of PRV eligibility to September 30, 2029 would fit a pattern where prior positive updates, such as Phase 2b data and financing milestones, sometimes preceded drawdowns. The presence of an active $100,000,000 shelf may keep dilution concerns in focus, even around favorable policy changes. Subsequent progress on the OST-HER2 BLA and clarity on funding plans could be important for sentiment stabilization.

Key Terms

rare pediatric disease designation, priority review voucher, biologics license application, platform technology designation program, +4 more

8 terms

rare pediatric disease designation regulatory

"Through the reauthorization of the Rare Pediatric Disease Designation (RPDD) Priority..."

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

"will remain eligible to receive a PRV from September 30, 2026, to September 30, 2029."

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.

biologics license application regulatory

"deadline for the Company to receive a Biologics License Application (BLA) for OST-HER2..."

A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.

platform technology designation program regulatory

"benefits afforded by the FDA Platform Technology Designation Program for Drug Development."

A platform technology designation program is an internal or regulatory label given to a core technology that can be reused across multiple products or applications. For investors, it signals that a company has a building block—like a smartphone operating system for many apps—that can lower development costs, speed product launches, expand markets, and create recurring or scalable revenue streams, reducing risk compared with one-off products.

orphan disease designation regulatory

"OST-HER2 has received FDA 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 FDA & 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.

accelerated approval regulatory

"Under the RPDD program, if the Company receives Accelerated Approval prior to..."

Accelerated approval is a process that allows new medical treatments to be approved more quickly than usual if they address serious or life-threatening conditions and show promising early results. For investors, it signals that a treatment may reach the market sooner, potentially boosting a company's prospects, but it also involves some uncertainty since full evidence of effectiveness is still being gathered.

immunotherapies medical

"the world leader in listeria-based cancer immunotherapies, is honored to celebrate..."

Immunotherapies are medical treatments that strengthen or guide the body's own immune system to recognize and fight disease cells, such as cancer or chronic infections. They matter to investors because they can produce long-lasting patient responses, command premium prices, and reshape standard care—similar to installing a smarter security system that prevents repeat break-ins—creating significant commercial upside but also clinical and regulatory risk.

AI-generated analysis. Not financial advice.

New York, New York--(Newsfile Corp. - February 4, 2026) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, is honored to celebrate the passage of the Mikaela Naylon Give Kids A Chance Act. Mikaela, like so many other children, courageously battled pediatric cancer - specifically Osteosarcoma. Her legacy through this legislation will accelerate critical opportunities for research and therapeutic access for other children and teens currently living with pediatric cancers.

Innovation is urgent and direly needed as pediatric cancers remain the leading disease-based cause of pediatric death in the United States. OS Therapies is empowered to continue its groundbreaking work combating osteosarcoma, where there is still significant unmet need for patients - primarily children and teens.

Through the reauthorization of the Rare Pediatric Disease Designation (RPDD) Priority Review Voucher (PRV) program, OS Therapies can continue their dedicated efforts with an extended deadline for the Company to receive a Biologics License Application (BLA) for OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma. The Company will now remain eligible to receive a PRV from September 30, 2026, to September 30, 2029.

The reauthorization of the program also incentivizes OS Therapies to re-evaluate the development of other pipeline products across its listeria-based cancer immunotherapy platform in the context of potential additional PRV opportunities, and benefits afforded by the FDA Platform Technology Designation Program for Drug Development. The Company will provide further details regarding the outcome of this evaluation process after the current sequence of marketing authorization submissions for its lead osteosarcoma candidate is completed.

OS Therapies is grateful for the positive impact of Mikaela's and some many other patients' legacy, and the Company is committed to building upon it to transform the lives of children and teens living with osteosarcoma and other rare cancers.

OST-HER2 has received FDA Orphan Disease Designation (ODD) and Fast Track Designation from FDA & 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, 2029, it will become eligible to receive a Priority Review Voucher (PRV).

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 Rare Pediatric Disease Designation (RPDD) from the U.S. Food & Drug Administration and Fast-Track and Orphan Drug designations from the U.S. FDA and 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. The Company is submitting a Biologics Licensing Application (BLA) to the U.S. FDA for OST-HER2 in osteosarcoma and, if approved, would become eligible to receive a Priority Review Voucher that it could then sell. 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.

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 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/282703

FAQ

What did OS Therapies (OSTX) announce about PRV eligibility on February 4, 2026?

OS Therapies announced the PRV program reauthorization extends eligibility from Sept 30, 2026 to Sept 30, 2029. According to the company, this preserves priority review incentives for OST-HER2 and other pipeline evaluations tied to pediatric rare-disease designations.

Does OST-HER2 (OSTX) currently qualify for regulatory incentives that could lead to a PRV?

Yes. OST-HER2 holds FDA Orphan Disease Designation, FDA and EMA Fast Track, and FDA Rare Pediatric Disease Designation. According to the company, these designations support potential PRV eligibility if Accelerated Approval is achieved before Sept 30, 2029.

How does the Mikaela Naylon Act reauthorization affect OS Therapies' OST-HER2 development timeline?

The reauthorization extends the window for PRV receipt through Sept 30, 2029, offering more regulatory runway. According to the company, this allows re-evaluation of OST-HER2 and other programs in light of potential PRV opportunities.

Will OS Therapies (OSTX) automatically receive a PRV after the reauthorization?

No. A PRV is not automatic; it requires the company to obtain Accelerated Approval for OST-HER2 before Sept 30, 2029. According to the company, receipt of a PRV remains conditional on meeting that regulatory milestone.

What next steps did OS Therapies (OSTX) say it will take after the PRV program reauthorization?

The company said it will re-evaluate other pipeline products for PRV potential and FDA Platform Technology Designation benefits. According to the company, further details will follow after completing the current sequence of marketing authorization submissions.