OS Therapies Incorporated (NYSE American: OSTX) announced today that the last patient (Patient #41) in the AOST-2121 clinical trial of OST-HER2 for recurrent, resected Osteosarcoma has received their final treatment dose. This patient is expected to complete the final radiological imaging evaluation, a key part of the 12-month Event Free Survival (EFS) analysis, by early Q4 2024. The company will soon close all trial sites and lock the database in preparation for data analysis, with topline results anticipated in Q4 2024.
OST-HER2, a biologic therapeutic candidate, is a Listeria monocytogenes (Lm) vector-based immunotherapy designed to prevent metastasis, delay recurrence, and improve overall survival in Osteosarcoma patients. The AOST-2121 study aims to demonstrate the efficacy of OST-HER2 in patients with recurrent disease who are at high risk of further recurrence. The study involves 16 doses of OST-HER2 administered every three weeks, with a follow-up four weeks after the final dose, totaling 52 weeks. The treatment generates T-cells targeting HER2-expressing tumor cells, potentially reducing or halting recurrence. Currently, there are no approved adjuvant treatments for recurrent Osteosarcoma in the U.S.
The AOST-2121 trial has reached full enrollment, with 41 patients treated at 21 sites across the U.S. The primary endpoints are EFS at 12 months and Overall Survival (OS) at 36 months, with interim OS data at 12 and 24 months. Topline EFS and interim 2-year OS data, along with additional secondary analyses, are expected in Q4 2024. There have been no novel FDA-approved therapies for Osteosarcoma in over 40 years.
The addition of data from Patient #41 and Patient #40 will complement the interim data presented at ASCO 2024. OS Therapies also plans to pursue Breast cancer treatments following Osteosarcoma and appreciates the support from patients, families, clinicians, and the Osteosarcoma community.
About OS Therapies
OS Therapies is a clinical-stage oncology company dedicated to developing and commercializing treatments for Osteosarcoma and other solid tumors. Its lead asset, OST-HER2, uses Listeria bacteria’s immune-stimulatory effects to target HER2 protein. The company has completed a Phase 2b trial of OST-HER2 in recurrent Osteosarcoma, with results expected in Q4 2024. OS Therapies also advances its next-generation Antibody Drug Conjugate (ADC) platform, featuring tunable antibody-linker-payload candidates and proprietary silicone linker technology.
