• Portfolio covers high-purity Z-endoxifen enteric formulations, performance characteristics, and manufacturing methods, part of Atossa's multi-jurisdiction IP strategy to support clinical and commercial plans

SEATTLE, Oct. 13, 2025 /PRNewswire/ -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) ("Atossa" or the "Company"), a clinical-stage biopharmaceutical company developing new approaches in breast cancer treatment and prevention, announces key progress in its global intellectual-property strategy for Z-endoxifen, including the issuance of an Israeli patent and continued renewals that reinforce protection for the Company's lead program across major jurisdictions. The Israeli patent (No. 304863), titled, "Methods for Making and Using Endoxifen," was granted on July 2, 2025, with priority to multiple U.S. provisional applications filed in 2017–2018.

The allowed claims in Israel include oral, delayed-release (enteric) dosage forms comprising at least 90% by weight Z-endoxifen, with optional impurity limits (<2%), defined release characteristics in gastric and intestinal media, dose strengths (e.g., 1–4 mg and 8 mg), and pharmacokinetic performance targets (e.g., plasma exposures and steady-state levels). The claims also cover manufacturing methods that enrich the Z-isomer via stepwise crystallization and solvent control. These protections align with Atossa's quality-by-design approach to deliver a consistent, high-purity Z-endoxifen product.

In parallel, Atossa received a Certificate of Patent Renewal from the Israel Patent Office confirming fee payment and renewal status for Patent No. 304863, further supporting the life-cycle management of Z-endoxifen IP in this jurisdiction.

"Strong, durable patents are foundational to our Z-endoxifen strategy," said Steven Quay, M.D., Ph.D., Atossa Therapeutics Chairman and CEO. "This new protection in Israel, together with our broader global filings, covers what we believe are the critical elements of product quality, performance, and manufacturing needed to bring Z-endoxifen to patients and to create long-term value for shareholders."

About the Patent Scope in Israel

The granted patent includes: (i) enteric oral formulations with ≥90% Z-endoxifen; (ii) optional impurity and residual-solvent limits; (iii) stability and delayed-release attributes (acid resistance and intestinal release); (iv) dose ranges including 1–4 mg and 8 mg; (v) PK targets such as steady-state plasma levels and exposure ranges; and (vi) a multi-step crystallization process to enrich the Z-isomer. Collectively, these claims support Atossa's global protection for Z-endoxifen composition, performance, and process.

About Atossa Therapeutics

Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company developing innovative therapies for significant unmet needs in breast cancer. Atossa's strategy emphasizes disciplined capital allocation, focusing resources on programs and data packages that can enable future regulatory submissions and potential commercialization. For more information, visit www.atossatherapeutics.com and refer to Atossa's filings with the U.S. Securities and Exchange Commission (SEC).

Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding Atossa's commercial readiness, financing strategy, operational plans, and the development and potential commercialization of (Z)-endoxifen. These statements are subject to risks and uncertainties that could cause actual results to differ materially, including market conditions, regulatory outcomes, clinical results, manufacturing and supply, intellectual-property challenges, and the Company's ability to secure sufficient funding on acceptable terms. For a discussion of risks and uncertainties, please refer to Atossa's filings with the U.S. Securities and Exchange Commission. Atossa undertakes no obligation to update forward-looking statements, except as required by law.

Source Documents (Israel)

• Certificate of Patent—No. 304863; Title: Methods for Making and Using Endoxifen; Filing 2018-09-10; Grant 2025-07-02; Priority to U.S. provisionals.
• Certificate of Patent Renewal—No. 304863 (Israel Patent Office).
• Allowed claims, including high-purity Z-endoxifen enteric formulations, release/PK attributes, and manufacturing steps.