UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended: September 30, 2025 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________ to __________ Commission File Number: 001-42195 OS THERAPIES INCOPORATED (Exact name of registrant as specified in its charter) (State or othe ...

Core Insights - OS Therapies announced additional overall and event-free survival data from its Phase 2b clinical trial of OST-HER2 in recurrent, fully resected, pulmonary metastatic osteosarcoma, highlighting statistically significant positive outcomes [2][4] Company Overview - OS Therapies is a clinical-stage oncology company focused on developing treatments for osteosarcoma and other solid tumors, with its lead asset OST-HER2 being an immunotherapy that targets the HER2 protein [4][6] - OST-HER2 has received several designations from regulatory agencies, including Rare Pediatric Disease Designation and Fast-Track status from the U.S. FDA [4] Clinical Trial Results - The Phase 2b Osteosarcoma Trial involved 41 patients, with subgroup analyses revealing: - For patients with a lung-only second or greater metastatic event, the 2-year overall survival rate was 80.0% [5] - For patients with a lung-only first metastatic event, the 2-year overall survival rate was 73.8%, significantly higher than the 30% natural history comparator (p < 0.0001) [5] - The company anticipates submitting a Biologics License Application (BLA) to the U.S. FDA for OST-HER2 in 2025 [6] Future Plans - OS Therapies is preparing for regulatory meetings with the FDA, MHRA, and EMA to discuss overall survival data and trial design for OST-HER2 [3] - The company is also advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced drug delivery [7]

Core Insights - OS Therapies has received a second Type C Meeting from the FDA to discuss clinical efficacy data endpoints for OST-HER2, aimed at supporting a Biologics Licensing Application under the Accelerated Approval Program following a successful Phase 2b trial for metastatic osteosarcoma [1][2] - The UK MHRA has granted a pre-MAA Meeting for the same program, with the company planning to align BLA and MAA submission timelines as part of Project Orbis [2] - The company reported positive results from its Phase 2b clinical trial, demonstrating statistically significant benefits in the 12-month event-free survival primary endpoint [6] Company Overview - OS Therapies is a clinical-stage oncology company focused on developing treatments for osteosarcoma and other solid tumors, with its lead asset OST-HER2 being an immunotherapy targeting the HER2 protein [4][6] - OST-HER2 has received multiple designations from regulatory agencies, including Rare Pediatric Disease Designation and Fast-Track status from the FDA [4] - The company is also advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced drug delivery [7] Clinical Development and Regulatory Strategy - The FDA meeting is scheduled for December 11, 2025, allowing time for the company to gather biomarker data to correlate immune activation with clinical outcomes [1][5] - The recent FDA/Osteosarcoma Institute Workshop emphasized the importance of overall survival data as a key efficacy endpoint and discussed appropriate clinical trial designs for future immunotherapies [3][5] - The company anticipates submitting a BLA for OST-HER2 in 2025, which, if approved, would make it eligible for a Priority Review Voucher [6]

Core Insights - OS Therapies announced statistically significant positive final 2-year overall survival data from the Phase 2b trial of OST-HER2, showing 75% of treated patients achieved 2-year overall survival compared to 40% in historical controls [1][4] - The company is on track to file for conditional marketing authorization in the UK, the US, and the EU, with key regulatory meetings planned for December 2025 [3][6] Group 1: Clinical Trial Results - 75% of OST-HER2 treated patients achieved 2-year overall survival, significantly higher than the 40% in historical controls (p < 0.0001) [1][4] - Subgroup analysis indicated that 100% of patients who achieved 12-month Event Free Survival (EFS) also achieved 2-year overall survival [1][4] Group 2: Regulatory Path and Future Plans - The company plans to submit a conditional Marketing Authorization Application (MAA) to the MHRA in December 2025 and a Biologics Licensing Application (BLA) to the FDA in January 2026 [3][6] - OS Therapies is analyzing patient samples to confirm correlations between clinical outcomes and immune system biomarker activation, with results expected in November 2025 [3] Group 3: Company Overview and Product Pipeline - OS Therapies focuses on developing treatments for Osteosarcoma and other solid tumors, with OST-HER2 as its lead asset, which has received multiple designations from regulatory agencies [6][7] - The company is also advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced treatment delivery [7]

Core Insights - OS Therapies received a positive regulatory update from the European Medicines Agency (EMA) following a meeting with the Dutch Medicines Evaluation Board (MEB) on October 6, 2025, regarding its OST-HER2 Phase 2b clinical trial for osteosarcoma [2][3] Regulatory Developments - The meeting aligned on key areas such as safety, non-clinical data, and chemistry, manufacturing, and controls (CMC) data, supporting the ongoing clinical trial [3][8] - The overall survival results from the trial, showing statistically significant final two-year data, may serve as a primary endpoint for conditional marketing authorization (CMA) [3][8] - A formal EMA Scientific Advice is anticipated in December 2025, establishing a potential pathway for a confirmatory randomized clinical development program [4][10] Clinical Trial Insights - The safety profile from the Fully Resected Osteosarcoma clinical study was confirmed as positive, with data from over 500 patients treated across four other therapeutic indications potentially supporting a CMA [8] - The rapporteur indicated that overall survival (OS) could provide a stronger measure of clinical benefit compared to 12-month Event-Free Survival (EFS) [8] - Efficacy data from other settings, such as recurrent, unresectable pulmonary metastatic osteosarcoma, could be incorporated into a post-market confirmatory clinical development program [8] Market Access and Future Plans - OS Therapies has commenced the Marketing Authorisation Application (MAA) submissions process with the UK MHRA, which has granted an expedited Market Access Scientific Advice Meeting [6] - The company plans to pursue a conditional marketing authorization while advancing a global randomized clinical study to evaluate OST-HER2 in various osteosarcoma clinical settings [10] - OST-HER2 has received multiple designations from the U.S. FDA and EMA, including Rare Pediatric Disease Designation and Fast-Track status [11]

Core Insights - OS Therapies is actively participating in multiple conferences and events in October 2025, showcasing its commitment to advancing cancer treatment and engaging with industry stakeholders [1][2][3][4][5]. Company Overview - OS Therapies Inc. is a clinical-stage biotechnology company focused on developing treatments for Osteosarcoma and other solid tumors, with its lead asset being OST-HER2, an immunotherapy targeting the HER2 protein [5][6]. - OST-HER2 has received several designations from the U.S. FDA, including Rare Pediatric Disease Designation, Fast-Track, and Orphan Drug designations, indicating its potential significance in treating rare diseases [5]. - The company reported positive results from its Phase 2b clinical trial of OST-HER2, demonstrating statistically significant benefits in the 12-month event-free survival primary endpoint for patients with recurrent, fully resected, lung metastatic osteosarcoma [5]. Upcoming Events - OS Therapies will participate in the Cell and Gene Meeting on the Mesa from October 6-8, 2025, in Phoenix, AZ, focusing on partnering and one-on-one meetings [2]. - The company will also attend the Roth Annual Healthcare Opportunities Conference on October 9, 2025, in New York City, where it will engage in meetings with potential investors [2]. - A workshop on advancing osteosarcoma drug development will take place on October 10, 2025, in Washington, DC, where OS Therapies management will be available for discussions [2]. - The BIOFuture 2025 event is scheduled for October 13-15, 2025, in New York City, featuring a spotlight panel and one-on-one meetings [3]. - The company will be present at the 52nd Daytime Emmy Awards on October 17, 2025, where its documentary "Shelter Me: Cancer Pioneers" has received two nominations [3]. - The Maxim Growth Summit will occur on October 22, 2025, in New York City, where corporate presentations and meetings will be held [4]. - OS Therapies will also participate in BIO - Europe from November 3-5, 2025, in Vienna, Austria, focusing on partnering and meetings [5]. Product Development - OST-HER2 has shown preclinical efficacy in various models of breast cancer and has been conditionally approved by the U.S. Department of Agriculture for treating canines with osteosarcoma [5]. - The company is advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced drug delivery [6].

Core Viewpoint - OS Therapies is advancing its regulatory submissions for OST-HER2, focusing on obtaining marketing authorizations in the UK and US for the treatment of pulmonary metastatic osteosarcoma, with submissions expected in late 2025 and early 2026 [3][7]. Regulatory Update - The company has updated its regulatory filing sequence to prioritize the UK MHRA conditional Marketing Authorisation Application (MAA) submission, which is expected to be completed in December 2025, followed by the US FDA Biologics Licensing Application (BLA) submission in January 2026 [3][7]. - A conditional MAA Pre-Submission Request has been submitted to the MHRA, and the company anticipates receiving formal acceptance for a rolling review request soon [4]. Clinical Trial Insights - The information in the MHRA conditional MAA submission aligns closely with the planned US FDA BLA submission, with the exception of the acceptable comparator arm for efficacy data [5]. - The company aims to use immune activation biomarker data as a surrogate marker correlated with overall survival to support its Accelerated Approval request [5][7]. Company Background - OS Therapies is a clinical-stage oncology company focused on developing treatments for osteosarcoma and other solid tumors, with OST-HER2 being its lead asset [8]. - OST-HER2 has received several designations from the FDA, including Rare Pediatric Disease Designation and Fast-Track designation, and has shown statistically significant benefits in its Phase 2b clinical trial [8]. Future Developments - The company is also advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced drug delivery [9].

Core Insights - OS Therapies has been invited to participate in the "Beyond the Cure: The Brave New World of Revolutionary Cancer Therapeutics" Spotlight Panel at BioFuture 2025, highlighting its focus on innovative cancer treatments [1][3] - The company plans to submit a Biologics Licensing Application (BLA) to the FDA in Q4 2025, aiming for approval that could lead to a Priority Review Voucher (PRV) sale to fund further clinical development [2][4] - OS Therapies' lead asset, OST-HER2, is an immunotherapy targeting HER2 protein, showing promising results in clinical trials for osteosarcoma and breast cancer [4][5] Company Overview - OS Therapies is a clinical-stage oncology company focused on developing treatments for osteosarcoma and other solid tumors, leveraging a unique listeria monocytogenes platform technology [3][4] - The company has received multiple designations from the FDA, including Rare Pediatric Disease Designation and Fast-Track status for OST-HER2, which has shown statistically significant benefits in clinical trials [4] - OS Therapies is also advancing next-generation Antibody Drug Conjugates (ADCs) and Drug Conjugates (DCs) through its proprietary technology [5][6]

Core Insights - OS Therapies has completed the last patient visit in its Phase 1b clinical trial for OST-504, focusing on biochemically recurrent prostate cancer, with a total of 7 patients enrolled [1][2] - The company is optimistic about the potential of OST-504 in various prostate cancer settings and plans to report study results in Q4 2025 [2] - Prostate cancer represents a significant market opportunity, with 1 in 8 men diagnosed and 1 in 44 men dying from the disease, making it the second leading cause of cancer death among men [2] - The company is also preparing for a rolling submission for a Biologics Licensing Application (BLA) for OST-HER2 in osteosarcoma, which could lead to accelerated market access for OST-504 if successful [2][5] - Updated 2-year overall survival data from the Phase 2b trial of OST-HER2 will be released on October 10, 2025 [4] Company Overview - OS Therapies is a clinical-stage oncology company focused on developing treatments for osteosarcoma and other solid tumors, with OST-HER2 as its lead asset [3][5] - OST-HER2 has received multiple designations from the FDA, including Rare Pediatric Disease Designation and Fast-Track status, and has shown positive results in its Phase 2b clinical trial [3][5] - The company is advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary technology for enhanced drug delivery [6]

Core Insights - Stonegate Capital Partners has initiated coverage on OS Therapies Inc. (OSTX), highlighting significant clinical, regulatory, and financial advancements in Q2 2025 as the company approaches the launch of OST-HER2 for patients with recurrent, fully resected, pulmonary metastatic osteosarcoma [1][3] Clinical and Regulatory Developments - The FDA has confirmed that OST-HER2 qualifies as a Regenerative Medicine Advanced Therapy (RMAT) and has issued a Biologics License Application (BLA) number in preparation for an Accelerated Approval submission [1][3] - Final 12-month Event Free Survival (EFS) results from the Phase 2b trial showed a statistically significant improvement of 35% compared to 20%, alongside interim 2-year Overall Survival (OS) data of 66.6% versus 40%, indicating strong clinical benefits [5] Financial Position and Partnerships - OS Therapies has secured a U.S. commercial partnership with Eversana, positioning for a potential U.S. launch in the first half of 2026 [1][3] - The company completed warrant exchange financings raising approximately $7.9 million in Q3, extending its cash runway into 2027 and funding preparations for the commercial launch [5]