OS Therapies Announces FDA OST-HER2 Type D Meeting Elevated to Type B Pre-BLA Meeting

OS Therapies (NYSE: OSTX) said the FDA elevated its Type D biomarker meeting for OST-HER2 to a Type B pre-BLA meeting, shifting discussions toward Accelerated Approval.

Rhea-AI Summary

OS Therapies (NYSE: OSTX) said the FDA elevated its Type D biomarker meeting for OST-HER2 to a Type B pre-BLA meeting, shifting discussions toward Accelerated Approval. The company is targeting completion of its clinical data submission by end of Q1 2026 and seeks Accelerated Approval in H2 2026.

OST-HER2 holds FDA Orphan Drug, Fast Track, and Rare Pediatric Disease designations; a Priority Review Voucher sale comparable transaction was reported at $205 million in February 2026.

Positive

• FDA elevated meeting to Type B pre-BLA, signaling regulatory progress
• Company targets clinical data submission completion by end of Q1 2026
• OST-HER2 has Orphan Drug, Fast Track, and Rare Pediatric Disease designations
• Priority Review Voucher market comparables: reported sale at $205M (Feb 2026)

Negative

• Confirmatory randomized Phase 3 must be commenced before Accelerated Approval, a regulatory prerequisite
• Accelerated Approval timing depends on FDA acceptance and trial start; company targets H2 2026 which may be optimistic

Argus Mar 9 session

+8.92% close to close Open Argus

Details

News Market Reaction – OSTX

On Mar 9, the day this news came out, OSTX closed 8.92% above the previous close.

Data tracked by StockTitan Argus for the Mar 9 session.

Key Figures

Shelf registration size: $100,000,000 ATM program size: $18,000,000 Private placement proceeds: $2,000,000 +5 more

Shelf registration size

$100,000,000

S-3 shelf to offer securities

ATM program size

$18,000,000

At-the-market prospectus supplement

Private placement proceeds

$2,000,000

Gross cash from unsecured convertible notes

Notes principal amount

$2,200,000

Aggregate principal of 10.0% OID notes

Investor warrants

1,666,667 warrants

Warrants at $1.40 exercise price per share

Notes interest rate

4%

Annual interest on unsecured convertible notes

Recent PRV sale value

$205,000,000

Most recent publicly disclosed PRV transaction (Feb 2026)

CEO stock options grant

1,000,000 options

Options granted Oct 21, 2025 at $1.8 exercise price

Historical Context

5 past events · Latest: Feb 17

5 events

1. Feb 17

   Regulatory update

   24h Move

   -0.8%

   Global regulatory update and BLA timelines for OST-HER2 submissions.

2. Feb 04

   Policy/PRV update

   24h Move

   -5.7%

   Reauthorization of PRV program preserving OST-HER2 voucher eligibility.

3. Feb 02

   BLA initiation

   24h Move

   +2.2%

   Initiation of U.S. BLA filing and rolling review request for OST-HER2.

4. Jan 15

   Clinical data

   24h Move

   -5.8%

   Positive Phase 2b biomarker data linking biomarkers with overall survival.

5. Jan 14

   Subsidiary IPO plan

   24h Move

   +0.7%

   OS Animal Health S-1 filing and contemplated equity distribution to OSTX holders.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

type b pre-bla meeting, biologics license application (bla), accelerated approval, orphan drug designation, +3 more

7 terms

type b pre-bla meeting regulatory

"elevated OS Therapies' Type D Biomarker Meeting to a Type B pre-BLA Meeting"

A Type B pre-BLA meeting is a formal, scheduled discussion with the U.S. Food and Drug Administration held before a company files a Biologics License Application (BLA) to market a biologic drug. It’s an opportunity to confirm what data and documentation the agency expects and to resolve major questions that could delay approval—like checking a building’s blueprints with the inspector so investors can better gauge the timing and risk of a future approval decision.

biologics license application (bla) regulatory

"ongoing Biologics License Application (BLA) submission under the Accelerated Approval Program"

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 regulatory

"under the Accelerated Approval Program (Accelerated Approval) for OST-HER2"

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.

orphan drug designation regulatory

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

Orphan drug designation is a special status given to medicines developed to treat rare diseases affecting only a small number of people. This status often provides benefits like faster approval processes and financial incentives, making it more attractive for companies to develop these drugs. For investors, it signals potential for exclusive market rights and reduced competition, which can impact the drug’s profitability.

fast track designation regulatory

"received FDA Orphan Drug Designation (ODD) and Fast Track Designation from the FDA & EMA"

Fast track designation is a status the U.S. Food and Drug Administration grants to drugs intended to treat serious conditions and address an unmet medical need. It gives the developer more frequent communication with the FDA and can allow parts of the application to be reviewed on a rolling basis, and it may pave the way to priority review or accelerated approval. It can shorten development timelines, though it does not guarantee approval.

rare pediatric disease designation regulatory

"has also received Rare Pediatric Disease Designation (RPDD) from the 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.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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• FDA's elevated meeting status signals transition from biomarker data discussions to Accelerated Approval discussions

• OS Therapies on track to complete clinical data submission by the end of Q1 2026

New York, New York--(Newsfile Corp. - March 9, 2026) - OS Therapies Inc. (NYSE American: OSTX) ("OS Therapies" or "the Company"), the world leader in listeria-based cancer immunotherapies, today provided an update regarding ongoing conversations with the United States Food & Drug Administration (FDA) with regards to its ongoing Biologics License Application (BLA) submission under the Accelerated Approval Program (Accelerated Approval) for OST-HER2 in the prevention or delay of recurrent, fully resected, pulmonary metastatic osteosarcoma. FDA elevated OS Therapies' Type D Biomarker Meeting to a Type B pre-BLA Meeting, expected to occur shortly after the Company completes submission of its clinical data package to the agency, targeted for the end of the first quarter of 2026.

"We credit FDA with taking decisive action to help advance Accelerated Approval discussions regarding OST-HER2 for pediatric cancer patients with osteosarcoma," said Paul Romness, MPH, Chairman & CEO of OS Therapies. "With the biomarker analysis complete, and patent filings in process, we are poised to deliver data to the agency that we believe represents surrogate clinical efficacy sufficient to enable our ongoing BLA submission. Following key meetings with Key Opinion Leaders over the last few weeks, many of whom treated patients in our clinical trial, we believe we now have a clear path forward to establish confirmatory randomized Phase 3 trial that is required to have a commenced prior to being granted Accelerated Approval in the United States."

OST-HER2 has received FDA Orphan Drug Designation (ODD) and Fast Track Designation from the FDA & EMA and has also received Rare Pediatric Disease Designation (RPDD) from the FDA. Under the RPDD program, if the Company receives Accelerated Approval in the United States, it will become eligible to receive a Priority Review Voucher (PRV) that it intends to sell. The most recent publicly disclosed PRV transaction occurred in February 2026 at a reported value of $205 million. The Company is seeking to get Accelerated Approval for OST-HER2 in osteosarcoma in the second half of 2026.

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 anticipates receiving a Biologics Licensing 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 European Medicines Agency 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.

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
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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/287699

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the FDA elevation to a Type B pre-BLA meeting mean for OSTX OST-HER2?

It advances discussions from biomarkers to Accelerated Approval pathway. According to OS Therapies, the elevation signals a shift toward pre-BLA Accelerated Approval topics and follows planned submission of the clinical data package targeted for end of Q1 2026.

When will OS Therapies (OSTX) submit clinical data for OST-HER2 to the FDA?

The company is targeting completion by the end of Q1 2026. According to OS Therapies, it expects to submit the clinical data package to the FDA by that deadline, with the Type B pre-BLA meeting shortly after submission.

Is OST-HER2 eligible for a Priority Review Voucher and what is its potential value for OSTX?

OST-HER2 could generate a Priority Review Voucher if Accelerated Approval is received. According to OS Therapies, a recent comparable PRV transaction occurred in February 2026 at a reported value of $205 million.

What regulatory designations does OST-HER2 hold that affect OSTX's approval pathway?

OST-HER2 has Orphan Drug, Fast Track, and Rare Pediatric Disease designations. According to OS Therapies, these designations support accelerated pathways and PRV eligibility upon Accelerated Approval in the United States.

What key regulatory requirement could delay OSTX's Accelerated Approval for OST-HER2?

A confirmatory randomized Phase 3 trial must be commenced prior to grant of Accelerated Approval. According to OS Therapies, initiation of that Phase 3 trial is a required condition for Accelerated Approval in the U.S.