OS Therapies, Inc. (NYSE-A: OSTX), a clinical-stage immunotherapy firm, claimed to have received encouraging outcomes from its Phase 1b trial of OST-HER2, aimed at treating HER2-positive solid tumors, including breast cancer.
The study's findings, which also encompass positive preclinical breast cancer data, announced Wednesday, noted that the Phase 1b trial enrolled 12 patients with a history of HER2-positive cancers, predominantly breast cancer.
The company claimed that results indicated that the OST-HER2 immunotherapy was safe and well-tolerated, including at doses selected for the ongoing Phase 2b clinical trial in recurrent, resected osteosarcoma. This ongoing trial, known as AOST-2121, has shown interim positive results, and discussions with the FDA regarding a Breakthrough Therapy Designation are currently underway, it added.
In the preclinical studies, OST-HER2 demonstrated a 78% reduction in tumor size in a transgenic mouse model of breast cancer treatment. Additionally, it showed a 33% success rate in preventing breast cancer in treated mice versus none in the control group.
When combined with HER2-targeted antibodies, there was a 20% tumor size reduction and a 65% reduction in the cellular concentration of metastatic cells in the brain metastasis model.
OST-HER2 leverages the immune-stimulatory effects of Listeria bacteria to provoke a robust immune response targeting the HER2 protein. The FDA has granted the treatment Rare Pediatric Disease Designation, Orphan Drug Designation, and Fast Track Designation for osteosarcoma, a type of bone cancer. Although the current focus is on osteosarcoma, the company plans to extend development into breast cancer and other HER2-expressing cancers.
OS Therapies is also progressing with its next-generation Antibody Drug Conjugate platform, which includes a unique silicone linker technology enabling the delivery of multiple payloads per linker.
The OST-HER2 Lm vector platform technology has been administered to over 450 cancer patients across various clinical trials. The company anticipates results from its fully-enrolled Phase 2b clinical trial in the fourth quarter of 2024. Additionally, OST-HER2 has shown efficacy in multiple preclinical breast cancer models.
This article was generated with the support of AI and reviewed by an editor. For more information see our T&C.