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Atossa Therapeutics Announces Issuance of U.S. Patent No. 12,275,684, Further Strengthening (Z)-endoxifen Portfolio

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Atossa Therapeutics, Inc.
Atossa Therapeutics, Inc.

SEATTLE, April 22, 2025 (GLOBE NEWSWIRE) -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (“Atossa” or the “Company”), a clinical-stage biopharmaceutical company developing innovative medicines for breast cancer, today announced that the United States Patent and Trademark Office (USPTO) has granted a new patent (U.S. Patent No. 12,275,684) directed to enteric oral formulations comprising (Z)-endoxifen as well as methods of treating subjects with those oral formulations.

This newly granted patent further fortifies Atossa’s intellectual property portfolio surrounding its proprietary (Z)-endoxifen formulations, encompassing novel compositions and methods related to (Z)-endoxifen, a potent Selective Estrogen Receptor Modulator (SERM). Specifically, the patent covers enteric oral formulations of (Z)-endoxifen and salts thereof as well as their use in treating hormone-dependent breast and reproductive tract disorders.

“The issuance of U.S. Patent No. 12,275,684 marks a significant milestone in our mission to advance innovative treatments for breast cancer. This patent not only reinforces our commitment to protecting our intellectual property but also underscores our dedication to delivering effective therapeutic options to patients,” said Steven Quay, M.D., Ph.D., Atossa’s President and Chief Executive Officer. “We remain steadfast in our pursuit of scientific excellence and patient-centered solutions to address the persisting unmet medical needs in breast cancer treatment and prevention.”

Atossa's robust patent estate now includes multiple U.S. patents, collectively encompassing over 100 claims related to (Z)-endoxifen formulations and their clinical applications. This comprehensive and ongoing protection strategy bolsters the company's continued leadership in developing targeted therapies for hormone receptor-positive breast cancer.​

About (Z)-Endoxifen
(Z)-endoxifen is one of the most potent Selective Estrogen Receptor Modulator (SERM) for estrogen receptor inhibition and may cause estrogen receptor degradation. It has also been shown to have efficacy in the setting of patients with tumor resistance to other hormonal treatments. In addition to its potent anti-estrogen effects, (Z)-endoxifen has been shown to target PKCβ1, a known oncogenic protein, at clinically attainable blood concentrations. Finally, (Z)-endoxifen appears to deliver similar or even greater bone agonistic effects while resulting in little or no endometrial proliferative effects compared with standard treatments, like tamoxifen.

Atossa is developing a proprietary oral formulation of (Z)-endoxifen that is encapsulated to bypass the stomach, as acidic conditions in the stomach convert a significant proportion of (Z)-endoxifen to the inactive (E)-endoxifen. Atossa’s (Z)-endoxifen has been shown to be well tolerated in clinical studies of women with and without breast cancer. (Z)-endoxifen is currently being studied both for the treatment and prevention of breast cancer, including a program in metastatic breast cancer that was announced earlier this year.