Welcome to our dedicated page for Atossa Therapeutics news (Ticker: ATOS), a resource for investors and traders seeking the latest updates and insights on Atossa Therapeutics stock.
Atossa Therapeutics, Inc. develops clinical-stage medicines for oncology and other areas of unmet medical need. Its recurring news centers on (Z)-endoxifen, the company's lead product candidate, including breast cancer research, mammographic breast density data, and expansion into rare disease indications such as Duchenne muscular dystrophy and McCune-Albright Syndrome.
Company updates also cover FDA orphan and rare pediatric disease designations, clinical and preclinical data presentations, peer-reviewed publications, intellectual property developments, leadership additions, financial results, and capital-allocation commentary tied to Atossa's development strategy.
Atossa Therapeutics (Nasdaq: ATOS) reported two (Z)-endoxifen abstracts accepted for ASCO 2026. Preclinical data show robust estrogen receptor inhibition across key ESR1 mutations, while the ongoing Phase 2 EVANGELINE trial evaluates 40 mg daily (Z)-endoxifen plus goserelin as neoadjuvant therapy in premenopausal ER+/HER2- breast cancer.
Atossa Therapeutics (NASDAQ: ATOS)/b) announced acceptance of a review manuscript in on (Z)-endoxifen as a potential modulator of utrophin pathways in Duchenne muscular dystrophy (DMD).
The article outlines how (Z)-endoxifen may favor utrophin expression and function and proposes preclinical studies and biomarker development as next steps.
Atossa Therapeutics (Nasdaq: ATOS) will host a virtual key opinion leader event on May 19, 2026, highlighting development of its investigational SERM/D (Z)-endoxifen in ER-positive breast cancer.
The webinar will feature breast cancer expert Dr. Laura Esserman discussing emerging clinical and translational data, combination strategies, and development opportunities.
Atossa Therapeutics (Nasdaq: ATOS) reported Q1 2026 results and corporate updates for the quarter ended March 31, 2026. Key developments include FDA Orphan Drug and Rare Pediatric Disease designations for (Z)-endoxifen in DMD and RPD designation for McCune-Albright Syndrome, new preclinical DMD data, senior clinical hires, and a Q1 operating expense increase to $9.9 million.
R&D expenses rose to $4.8M (+15%), G&A to $5.1M (+56%), and interest income fell by $0.4M.
Atossa Therapeutics (Nasdaq: ATOS) announced publication of the KARISMA Endoxifen Phase 2 trial in JNCI showing that daily low-dose Endoxifen significantly reduced mammographic breast density (MBD) in healthy premenopausal women.
Both 1 mg and 2 mg doses reduced MBD versus placebo (1 mg: −19.3%, p=0.004; 2 mg: −26.5%, p<0.001) after six months, with a tolerability profile similar to placebo for 1 mg and no clinically significant lab or vital-sign changes reported.
Atossa Therapeutics (Nasdaq: ATOS) announced that the U.S. FDA granted Rare Pediatric Disease (RPD) designation to (Z)-endoxifen for treatment of McCune-Albright Syndrome (MAS) in females on May 4, 2026. RPD status may make the program eligible for a Priority Review Voucher (PRV) upon approval; disclosed PRV sales in the last 18–24 months ranged from approximately $100–$205 million. The company cited scientific rationale for (Z)-endoxifen as a potent SERM/D and noted engagement with the FD/MAS clinical and patient community while it defines a clinical development path for MAS.
Atossa Therapeutics (NASDAQ: ATOS) reported 2025 year-end results and corporate updates on March 25, 2026. Key regulatory milestones include FDA Rare Pediatric Disease designation (Dec 2025) and Orphan Drug designation (Jan 2026) for (Z)-endoxifen in Duchenne Muscular Dystrophy. Total operating expenses were $37.1 million in 2025 versus $27.6 million in 2024, driven by higher R&D and G&A costs.
The company highlighted peer-reviewed publication, clinical award recognition, new clinical hires, and increased clinical trial spending to advance (Z)-endoxifen across oncology and rare-disease programs.
Atossa Therapeutics (Nasdaq: ATOS) on March 19, 2026 added two senior clinical leaders: Kathy Puyana Theall, M.D. as Medical Director - Breast Oncology and Adebola Giwa, M.D. as Medical Director - Rare Diseases.
These hires bolster development of (Z)-Endoxifen across breast cancer and rare disease programs, including McCune-Albright syndrome and Duchenne muscular dystrophy, and bring regulatory and global trial experience to support upcoming clinical and regulatory milestones.
Atossa Therapeutics (Nasdaq: ATOS) presented preclinical data on (Z)-endoxifen at the 2026 MDA Clinical & Scientific Conference showing improved muscle strength, reduced damage biomarkers, better body composition, and tolerance in mdx5Cv dystrophic mice.
The company said results support continued clinical development for Duchenne muscular dystrophy.
Atossa Therapeutics (Nasdaq: ATOS) summarized 2025 progress and outlined 2026 priorities for its proprietary oral (Z)-endoxifen. Key developments include FDA Type C feedback (Nov 17, 2025), IND activity and a paused metastatic program, Rare Pediatric and Orphan Drug designations for DMD, new U.S. patent claims, a reverse stock split (effective Feb 2, 2026), and >$40 million cash on hand.
The company is completing I-SPY 2 enrollment, pursuing non-oncology indications (DMD, MAS), defending USPTO patent proceedings with Intas, and prioritizing regulatory interactions and partnership opportunities in 2026.