DEFA14A: OS Therapies Adjourns Annual Meeting, Highlights Pipeline

OS Therapies Incorporated adjourned its 2025 annual meeting to October 21, 2025, to solicit additional proxies, while also releasing an investor presentation detailing its clinical pipeline and strategic milestones.

Summary

• The 2025 annual meeting of stockholders, initially convened on October 14, 2025, was adjourned to October 21, 2025, to allow additional time for proxy solicitation.
• The Issuance Proposal, Charter Amendment Proposal, and Auditor Ratification Proposal received the requisite votes for approval based on preliminary tabulation.
• An investor presentation was posted on October 17, 2025, outlining the company's lead clinical program, OST-HER2, in Osteosarcoma, which has positive Phase 2b data.
• OST-HER2 has received Orphan Drug, Fast Track, and Rare Pediatric Disease Designations from the FDA and EMA.
• The company is targeting FDA Accelerated Approval for OST-HER2 in human osteosarcoma in Q2/Q3 2026, with potential for a Priority Review Voucher (PRV) estimated at ~$160M.
• The pipeline includes other Listeria-based immunotherapy candidates for HPV cancers, non-small cell lung cancer, glioblastoma, breast cancer, and prostate cancer, as well as a preclinical tunable drug conjugate (tADC) platform.
• Current financial summary indicates a stock price of $1.87, ~34M shares outstanding, a market cap of $60M, ~$4M cash, and a monthly cash burn of ~$300K.
• Total addressable market for the Listeria-based assets and follow-on applications is estimated at $258 billion, with the tADC platform market at $311 billion.

Sentiment

Score: 7

Explanation: The sentiment is moderately positive due to promising Phase 2b clinical data for OST-HER2 in osteosarcoma, multiple regulatory designations, and the potential for a significant Priority Review Voucher. However, this is tempered by the early stage of most pipeline assets, the current cash burn rate, and the procedural delay of the annual meeting.

Positives

• OST-HER2 Phase 2b trial in recurrent, resected metastatic osteosarcoma showed a 12-month Event Free Survival (EFS) of 35% compared to a published historical control of 20% (P-Value 0.0196).
• The 2-year Overall Survival (OS) for OST-HER2 treated patients was 75% compared to a published historical control of 40% (P-Value <0.0001).
• OST-HER2 has been granted Orphan Drug Designation, Fast Track Designation, and Rare Pediatric Disease Designation by the FDA and EMA.
• The potential for a Priority Review Voucher (PRV) upon FDA Accelerated Approval, with an estimated sale value of ~$160M, provides a significant non-dilutive funding opportunity.
• Positive proof-of-concept data has been observed for OST-HER2 in canine osteosarcoma, with plans for conditional approval launch in 2026.
• Preclinical and Phase 1 results for OST-HER2 in breast cancer are positive, with a Phase 2 trial anticipated in 2025.
• The company reports cash on hand into mid-2026, providing runway for near-term milestones.
• The management team has over 100 years of combined experience, including more than 20 product launches and 10 licensing deals.

Negatives

• The company has no source of predictable revenue and has incurred significant losses since inception, with a risk of never becoming profitable.
• Most product candidates are in early stages of development, and the approach to discovery and development is novel and unproven.
• The company has a monthly cash burn of approximately $300K, and current cash of ~$4M, indicating a need for future capital, even with the potential PRV.
• The annual meeting was adjourned to solicit additional proxies, which could indicate challenges in securing sufficient shareholder support for all agenda items or a desire for a stronger mandate.

Risks

• Success is primarily dependent on the successful development, regulatory approval, and commercialization of lead product candidates, which are in early stages of development.
• The approach to discovery and development of innovative products is novel and unproven, and may not result in marketable products.
• The company has no source of predictable revenue, has incurred significant losses since inception, may never become profitable, and may incur substantial and increasing net losses for the foreseeable future.
• Clinical trials of product candidates may fail to demonstrate safety and efficacy, preventing regulatory approvals.
• Regulatory approval processes are lengthy, time-consuming, and unpredictable, and approval may not be obtained from the FDA or foreign authorities.
• Even if regulatory approval is obtained, the market may not be receptive to the product candidates.
• The company may not be able to establish collaborative partnerships necessary for development, marketing approval, manufacturing, and commercialization.
• Difficulties may be encountered in satisfying clinical trial protocols, including patient enrollment.
• The company may face competition from other companies or claims from third parties alleging infringement of their intellectual property.

Future Outlook

The company anticipates several key regulatory milestones in late 2025 and early 2026, including meetings with the FDA, MHRA, and EMA, followed by BLA and MAA submissions for OST-HER2 in human osteosarcoma. Accelerated FDA approval is targeted for Q2/Q3 2026, which could lead to the sale of a Priority Review Voucher. Development for canine osteosarcoma and other cancer indications, including a Phase 2 trial for breast cancer and Phase 1 trials for ovarian cancer (tADC platform), are also planned for 2025-2026.

Management Comments

• Paul Romness was inspired to launch OS Therapies following the Osteosarcoma diagnosis of a close family friend.

Industry Context

The osteosarcoma market represents a significant unmet medical need, with no new treatments approved in over 40 years, positioning OS Therapies' OST-HER2 as a potential breakthrough. The company's Listeria-based platform and tunable drug conjugate (tADC) platform are part of the rapidly evolving and high-growth cancer immunotherapy and targeted drug delivery sectors, which are attracting substantial investment and research.

Comparison to Industry Standards

• Osteosarcoma has seen no new treatments in over 40 years, highlighting a critical unmet medical need compared to other cancer types with more active drug development.
• The estimated value of the Priority Review Voucher at ~$160M is benchmarked against a recent sale by Abeona in June 2026, indicating a competitive market value for such regulatory incentives.
• The OST-Lm platform aims to establish a new category within the broader $126 billion cancer immunotherapy market, suggesting a novel approach compared to existing therapies.

Corporate Governance

Stakeholder Impact

• Shareholders: Directly impacted by the annual meeting adjournment and the need to submit proxies. Potential for significant value creation from successful clinical development and PRV sale, but also risk of dilution from future capital raises.
• Patients (Osteosarcoma, Breast Cancer, etc.): Potential beneficiaries of novel therapeutic options if pipeline candidates achieve regulatory approval.
• Employees: Continued employment and potential growth opportunities tied to successful product development and commercialization.
• Regulatory Authorities (FDA, MHRA, EMA, USDA): Engaged in ongoing review and guidance processes for the company's product candidates.

Next Steps

• Continue soliciting votes from stockholders for the Annual Meeting.
• Reconvene the Annual Meeting on October 21, 2025.
• Conduct US FDA Type C Meeting on December 11, 2025.
• Hold UK MHRA Pre-MAA Meeting and EMA SAM Meeting in December 2025.
• File UK MHRA MAA for Approval in December 2025.
• File US FDA BLA for Approval in January 2026.
• File EMA MAA for Approval in Q1/2026.
• Determine regulatory pathway for OST-HER2 in Canine Osteosarcoma & spinoff in Q4/25 Q1/26.
• Meet with USDA to review new manufacturing process for reactivation of conditional approval for Canine OS in Q4/2025.
• Launch Canine OS under conditional approval in 2026.
• Sponsor confirmatory trial at UPenn Vet for full approval of Canine OS, expected in 2026.
• Anticipate Phase 2 trial for OST-HER2 in Breast Cancer in 2025.
• Work toward 2-Week & GLP toxicity trials for OST-tADC platform.
• Begin Phase 1 trials for ovarian cancer (OST-tADC) in 2025.

Key Dates

Recommendation

The company presents compelling positive Phase 2b data for OST-HER2 in osteosarcoma, a disease with high unmet medical need and orphan drug designations, coupled with the potential for a significant Priority Review Voucher. This offers substantial upside. However, the company is still in early clinical stages for most of its pipeline, has a limited cash runway relative to its burn rate, and faces inherent risks associated with drug development and regulatory approvals. The annual meeting adjournment, while procedural, adds a minor note of caution. A 'hold' recommendation is appropriate for seasoned investors, balancing the high-risk, high-reward profile with the need for further clarity on financing and continued clinical progress.

Keywords

Osteosarcoma, Cancer Immunotherapy, Listeria Platform, HER2, Drug Development, Biotechnology, Rare Pediatric Disease, FDA Approval, ADC, Oncology