Atossa Therapeutics, Inc.

Overview

• Clinical-stage biopharmaceutical company developing proprietary medicines in oncology (breast cancer and related breast conditions) and certain rare diseases.
• Lead drug candidate: oral (Z)-endoxifen, a selective estrogen receptor modulator (SERM/SERM-D) in Phase 2 development.
• Intellectual property: seven U.S. patents and 16 international patents covering (Z)-endoxifen; patent protection expected through at least November 17, 2038.

Business model and financial summary

• Clinical-stage company with no product sales to date.
• Revenue: none for the periods summarized.
• Net losses: $34.8 million in 2025; $25.5 million in 2024.
• Operating expenses: $37.141 million in 2025; $27.621 million in 2024 (R&D: $21.185 million in 2025; G&A: $15.956 million in 2025).
• Cash and liquidity: $41.3 million in unrestricted cash and cash equivalents as of December 31, 2025; total cash, cash equivalents, and restricted cash $41.4 million.
• Working capital: $37.4 million as of December 31, 2025.
• Management expects resources to fund planned operations for the next 12 months but anticipates additional capital will be required for longer-term development and potential regulatory approvals. Plans include raising capital through equity, debt, or collaborations.

Stock, capitalization, and financing

• Authorized common stock: 350,000,000 shares; outstanding: 8,611,361 shares (as of December 31, 2025).
• Reverse stock split: 1-for-15 split effective February 2, 2026.
• Preferred stock: Series B convertible preferred stock existed; 5 shares converted to 95 shares of common stock in 2025; no warrants outstanding as of December 31, 2025.
• At-the-market (ATM) financing:
  • Prior ATM with Jefferies LLC canceled February 19, 2026.
  • New ATM facility with Rodman & Renshaw LLC announced February 20, 2026, allowing up to $50 million in shares to be sold.
• Stockholders: approximately 33 stockholders of record as of March 17, 2026.

Major programs and clinical development

Oncology / Breast Cancer

• Karisma Study (Phase 2): oral (Z)-endoxifen in healthy premenopausal women with mammographic breast density (MBD). Dosing arms: 1 mg and 2 mg versus placebo.
  • Top-line data expected in Q1 2026.
  • Six-month results showed dose-responsive reductions in MBD: 1 mg reduced MBD by 17.3%; 2 mg by 23.5%; placebo change minimal.
  • Plasma concentrations: approximately 4.8 ng/mL (1 mg) and 9.7 ng/mL (2 mg).
  • Adverse events: 2 mg arm reported more hot flashes, night sweats, and vaginal discharge; 1 mg arm had adverse event rates similar to placebo.
• RECAST DCIS Study: neoadjuvant evaluation of (Z)-endoxifen under the QLHC platform to assess potential for active surveillance.
• EVANGELINE Study: amended in 2025 from a two-part design to a single-arm, open-label Phase 2 with two cohorts (Cohorts A and B). The study will assess short-interval endpoints (Ki-67 response and RECIST). Enrollment anticipated at 40–65 patients; completion expected in 2H 2026.
• I-SPY 2 Endocrine Optimization Pilot (I-SPY 2 EOP): neoadjuvant Phase 2 arms testing (Z)-endoxifen alone and in combination with FDA-approved drugs (abemaciclib and elagolix). Enrollment across arms expected to be about 90 participants; combination arm data expected in 2H 2026.

Rare diseases

• Duchenne Muscular Dystrophy (DMD): preclinical and early development focus; FDA engagement began in Q4 2025.
  • FDA designations (Dec 2025–early 2026): Rare Pediatric Disease Designation and Orphan Drug Designation for (Z)-endoxifen in DMD.
  • Exploring potential relevance in symptomatic women carriers of DMD and potential for Orphan designation.
• McCune-Albright Syndrome (MAS): evaluating (Z)-endoxifen as a hormone blocker to reduce early puberty effects; pursuing Rare Pediatric Disease and Orphan designations in 1H 2026.

Manufacturing and development

• Proprietary manufacturing process for (Z)-endoxifen with defined processes for API and drug product and manufacturing redundancies with qualified suppliers.

Legal and contingencies

• Ongoing litigation related to Intas Pharmaceuticals and patents: PGR and IPR petitions filed in 2025; institution decisions granted in 2025; responses filed in January 2026; final decisions expected by November 2026.
• Other litigation and claims typical for a biotech company; management believes none have a material standalone or aggregate financial impact at present.

Off-balance sheet items and commitments

• Non-cancellable clinical trial contracts with estimated non-cancellable commitments of about $7.0 million as of December 31, 2025.
• Australian R&D tax rebate liability: $1.1 million in 2025 and $1.5 million in 2024 recognized in other current liabilities.

Governance and reporting

• Chief Executive Officer and Chief Medical Officer: Steven C. Quay.
• Chief Financial Officer: Mark J. Daniel.
• The company operates a single reporting segment with the chief operating decision maker at the corporate level.

Summary

Atossa Therapeutics is a clinical-stage biotechnology company focused on (Z)-endoxifen for breast cancer risk reduction, neoadjuvant treatment settings, and several rare pediatric indications. The company reports active Phase 2 programs, patent protection through at least 2038, ongoing regulatory interactions for rare disease designations, and a finite cash runway with plans to raise additional capital to support development and potential regulatory milestones.