Atossa Therapeutics Issues Letter to Shareholders Highlighting 2025 Accomplishments and 2026 Outlook

Company provides update on clinical programs and recent events

Published on Feb. 12, 2026

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Atossa Therapeutics, a clinical-stage biopharmaceutical company, issued a letter to shareholders highlighting its key accomplishments in 2025 and outlining its priorities for 2026. The letter discusses the company's progress in advancing its proprietary oral (Z)-endoxifen therapy, including regulatory clarity from the FDA, advancements in breast cancer neoadjuvant therapy trials, and the exploration of (Z)-endoxifen's potential in treating Duchenne muscular dystrophy and McCune-Albright syndrome. The letter also touches on the company's efforts to strengthen its intellectual property portfolio, leadership team, and financial discipline.

Why it matters

Atossa's progress with (Z)-endoxifen, a selective estrogen receptor modulator/degrader, could lead to new treatment options for breast cancer and other rare diseases with significant unmet need. The company's strategic focus on regulatory clarity, clinical development, and intellectual property protection positions it to potentially bring innovative therapies to patients.

The details

Key highlights from Atossa's 2025 accomplishments include:- Regulatory clarity from the FDA on potential expedited development pathways for (Z)-endoxifen in oncology and non-oncology indications.- Advancements in the I-SPY 2 neoadjuvant breast cancer trial, including (Z)-endoxifen monotherapy and combination therapy arms.- Exploration of (Z)-endoxifen's potential in treating Duchenne muscular dystrophy and McCune-Albright syndrome, leading to FDA designations that could provide strategic benefits.- Strengthening of the company's intellectual property portfolio and leadership team to support future clinical and commercial progress.

  • In November 2025, Atossa completed a Type C meeting with the FDA to discuss the regulatory strategy for advancing (Z)-endoxifen in breast cancer.
  • In the fourth quarter of 2025, Atossa submitted an IND application to the FDA for a Phase 2 dosing study of (Z)-endoxifen in metastatic breast cancer, but later decided to pause investment in this indication.
  • In December 2025 and early 2026, Atossa received Rare Pediatric Disease Designation and Orphan Drug Designation from the FDA for (Z)-endoxifen in the treatment of Duchenne muscular dystrophy.
  • In late 2025, Atossa initiated the process to affect a reverse stock split, which was effective on February 2, 2026.
  • Atossa entered 2026 with more than $40 million in cash and cash equivalents, which the company believes supports more than one year of working capital.

The players

Atossa Therapeutics, Inc.

A clinical-stage biopharmaceutical company developing innovative medicines in oncology and other areas of significant unmet need.

Steven Quay, M.D., Ph.D.

President and Chief Executive Officer of Atossa Therapeutics.

Janet R. Rea, MSPH

Appointed as Senior Vice President of R&D at Atossa Therapeutics to oversee late-stage (Z)-endoxifen programs.

Mark Daniel, CPA

Appointed as Chief Financial Officer of Atossa Therapeutics to lead finance, systems, and capital strategy.

Eli Lilly and Company

A pharmaceutical company that markets abemaciclib (VERZENIO®), which is being evaluated in combination with (Z)-endoxifen in Atossa's I-SPY 2 trial.

AbbVie, Inc.

A pharmaceutical company that markets elagolix (ORILISSA®), which is being evaluated in combination with (Z)-endoxifen in Atossa's I-SPY 2 trial.

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What they’re saying

“Our mission remains straightforward: develop a differentiated, patient-centered endocrine therapy that can meaningfully improve outcomes across the breast cancer spectrum and other therapeutic areas with significant unmet need, and create sustainable value for shareholders along the way.”

— Steven Quay, M.D., Ph.D., President and Chief Executive Officer (Atossa Therapeutics Investors)

What’s next

Atossa plans to complete enrollment in the combination therapy arms of the I-SPY 2 trial in the first half of 2026, with preliminary data becoming available throughout the year. The company also plans to advance strategic planning for the Duchenne muscular dystrophy program, including assessment of development pathways and clinical trial designs that leverage the Rare Pediatric Disease and Orphan Drug designations.

The takeaway

Atossa Therapeutics is making progress in developing its proprietary (Z)-endoxifen therapy, with a focus on oncology and rare disease indications. The company's strategic clarity, regulatory progress, and strengthened leadership and intellectual property position it to potentially bring innovative treatments to patients in need.