Atossa Therapeutics outlines 2025 progress and 2026 plans for drug development

Atossa Therapeutics Inc. (NASDAQ: ATOS) issued a shareholder letter detailing progress made in 2025 and outlining priorities for 2026, according to a company statement.

The clinical-stage biopharmaceutical company reported completing a Type C meeting with the U.S. Food and Drug Administration on November 17, 2025, regarding regulatory strategy for advancing (Z)-endoxifen in breast cancer treatment. The FDA provided feedback on potential expedited pathways and development options spanning metastatic disease, neoadjuvant treatment, and risk-reduction settings.

The company received two FDA designations for (Z)-endoxifen in treating Duchenne Muscular Dystrophy (DMD) in December 2025 and early 2026: Rare Pediatric Disease Designation and Orphan Drug Designation. These designations provide incentives including a potential Priority Review Voucher for future FDA applications and potential market exclusivity.

Atossa paused investment in (Z)-endoxifen for metastatic breast cancer after evaluating costs and timelines for Phase 2 and Phase 3 clinical trials, choosing to focus resources on other oncology areas and rare diseases.

The company received a U.S. patent covering enteric oral formulations and methods of use for (Z)-endoxifen. Atossa is defending its intellectual property in ongoing U.S. Patent and Trademark Office proceedings with Intas Pharmaceuticals Ltd., with updates expected in the first half of 2026.

Key leadership additions in 2025 included Janet R. Rea as Senior Vice President of R&D and Mark Daniel as Chief Financial Officer.

The company entered 2026 with more than $40 million in cash and cash equivalents. A reverse stock split became effective February 2, 2026, aimed at regaining compliance with Nasdaq listing requirements.

For 2026, Atossa plans to complete enrollment in I-SPY 2 combination therapy trials, pursue partnership opportunities, and advance strategic planning for DMD development while maintaining capital efficiency.

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