OS Therapies (NYSE American: OSTX) announced today that the last patient (Patient #41) enrolled in the AOST-2121 clinical trial (NCT04974008) for OST-HER2 in recurrent, resected osteosarcoma has completed their final radiographical evaluation at 52 weeks, marking the end of the treatment period. The Company is preparing to request a Type C Meeting with the U.S. Food & Drug Administration (FDA) to discuss potential protocol adjustments based on their recommendations. Once adjustments are made, the clinical trial database will be locked for data analysis, with topline results expected to be announced in Q4 2024.
In a concurrent announcement, the Company will ring the closing bell at the New York Stock Exchange today. President and CEO Paul Romness will also appear in two live interviews on national television:
- “B” Block in Market Movers on Fintech.TV at 9:10 AM on Thursday, October 3, 2024
- Trading 360 on the Schwab Network at 11:30 AM on Thursday, October 3, 2024
OST-HER2 is a biologic therapeutic candidate utilizing a Listeria monocytogenes (Lm) vector-based immunotherapeutic vaccine aimed at preventing metastasis, delaying recurrence, and improving overall survival in osteosarcoma patients. The AOST-2121 Phase 2b trial involved 41 patients across 21 U.S. clinical sites, focusing on those with recurrent metastatic disease to the lungs who are likely to experience further recurrences. Patients received 16 doses of OST-HER2 every three weeks, followed by a four-week evaluation period, totaling 52 weeks of study participation. Primary endpoints for the study include Event Free Survival (EFS) at 12 months and Overall Survival (OS) at 36 months, with interim OS data collected at 12, 18, and 24 months. Topline EFS and interim OS data, along with additional secondary analyses, are anticipated in Q4 2024.
The proposed mechanism of action for OST-HER2 involves stimulating both innate and adaptive immune responses through the Lm vector, generating T-cells capable of targeting and eliminating potential micro-metastases. Notably, there are currently no approved adjuvant treatments for recurrent osteosarcoma in the U.S., and no novel therapeutic interventions have been approved by the FDA in over 40 years.
About OS Therapies
OS Therapies is a clinical-stage oncology company focused on developing and commercializing treatments for osteosarcoma and other solid tumors. Its lead asset, OST-HER2, leverages the immune-stimulatory properties of Listeria to elicit a strong immune response against the HER2 protein. The Company has completed enrollment for its 41-patient Phase 2b clinical trial of OST-HER2 in resected, recurrent osteosarcoma, with results expected in Q4 2024. OST-HER2 has also completed a Phase 1 clinical study in breast cancer patients and has shown promising preclinical efficacy in various breast cancer models. Additionally, OST-HER2 has received conditional approval from the U.S. Department of Agriculture for treating canines with osteosarcoma. The Company is also advancing its next-generation Antibody Drug Conjugate (ADC) platform, known as tunable ADC (tADC), which utilizes proprietary silicone linker technology to deliver multiple payloads per linker.
