Atossa Therapeutics, Inc.

Atossa Therapeutics, Inc. is a clinical-stage biopharmaceutical company dedicated to developing novel therapies in oncology, with a primary focus on breast cancer and other related conditions. Headquartered in Seattle, Washington, the company's mission is to advance innovative medicines to address significant unmet medical needs, aiming to transform breast cancer care through scientific breakthroughs and patient-centric solutions.

The company's lead product candidate is oral (Z)-endoxifen, a proprietary selective estrogen receptor modulator/degrader (SERM/D) that is currently in Phase 2 clinical development. (Z)-endoxifen is being evaluated for both the treatment and prevention of breast cancer, with a focus on various settings including metastatic breast cancer, neoadjuvant treatment, and breast cancer risk reduction. Atossa is also exploring the potential of (Z)-endoxifen for indications beyond breast cancer, such as Duchenne Muscular Dystrophy (DMD) and McCune-Albright Syndrome (MAS).

Under the leadership of Chairman, CEO, and President Dr. Steven C. Quay, Atossa Therapeutics has recently made notable progress. In late 2025 and early 2026, the company accelerated its FDA strategy for (Z)-endoxifen, submitting an Investigational New Drug (IND) application for metastatic breast cancer and receiving a "Study May Proceed" letter from the FDA. Additionally, (Z)-endoxifen received both Rare Pediatric Disease Designation and Orphan Drug Designation from the FDA for Duchenne Muscular Dystrophy. The company also strengthened its clinical leadership team in March 2026 with the addition of new Medical Directors for Breast Oncology and Rare Diseases, and was recognized with the 2025 Clinical Trials Arena Research and Development Excellence Award in Precision Endocrine Therapy.