Funding activities

Atossa Therapeutics Phase 2 Breast Cancer Study of Endoxifen Produces Substantially Positive Results Allowing for Early Study Termination

SEATTLE, 02 Feb. 2021 (GLOBE NEWSWIRE) — Atossa Therapeutics, Inc. (Nasdaq:ATO), a clinical-stage biopharmaceutical company that seeks to discover and develop innovative medicines in areas of high unmet medical need, currently focused on breast cancer and COVID-19, today announces that , based on the substantially positive results achieved with patients enrolled to date in its Australian open-label Phase 2 clinical study of oral endoxifen administered within the “window of opportunity” between breast cancer diagnosis and surgery , Atossa has stopped the study and is accelerating its endoxifen program in the United States.

“It is a welcome development to stop an ongoing clinical trial because the results are extremely positive,” commented Steven Quay, MD, Ph.D., President and CEO of Atossa. “Data from the first six patients in our Australian Phase 2 Window of Opportunity study show an average reduction of 74% in Ki-67, which is a common measure of tumor cell activity, and that at the time of surgery, all patients had Ki-67. levels below 25%, which is an important threshold for improving long-term survival, as identified in studies by others. We believe that additional enrollment will not alter these positive results, so we are ending the study early. This saves at least a year off the development schedule, allowing us to accelerate clinical development in the United States. We look forward to reporting final data from all study patients and sharing our continued progress in the development of oral endoxifen. »

The study enrolled seven patients newly diagnosed with invasive stage 1 or 2 ER+ and human epidermal growth factor receptor negative (HER2-) breast cancer requiring mastectomy or lumpectomy. Patients received Atossa’s proprietary oral endoxifen for at least 14 days from the time of diagnosis until the day of surgery. The primary endpoint is whether oral administration of endoxifen reduces tumor activity as measured by Ki-67. Secondary endpoints are safety and tolerability and assessment of the study drug on estrogen and progesterone receptor expression levels. The Phase 2 study was conducted on behalf of Atossa by Avance Clinical, a leading Australian CRO.

The American Cancer Society (ACS) estimates that in 2020, 276,480 women will be diagnosed with breast cancer in the United States. Every two minutes, an American woman is diagnosed with breast cancer and 42,170 die from it each year.

Atossa is evaluating a number of potential clinical benefits and potential indications for its oral endoxifen in the window of opportunity. These may include avoidance of surgery in certain patients, such as elderly and/or frail patients, allowing breast-conserving surgery, and the use of endoxifen in place of other neoadjuvant therapies such as chemotherapy, aromatase inhibitors and other endocrine therapies like tamoxifen.

About Atossa Therapeutics

Atossa Therapeutics, Inc. is a clinical-stage biopharmaceutical company focused on discovering and developing innovative medicines in areas of high unmet medical need, with a current focus on breast cancer and COVID-19 . For more information, please visit

Forward-Looking Statements Disclaimer

The forward-looking statements contained in this press release, which Atossa assumes no obligation to update, are subject to risks and uncertainties that could cause actual results to differ materially from anticipated or estimated future results. , including, without limitation, statements regarding the satisfaction of the closing conditions relating to the offer and the intended use of the proceeds of the offer, the risks and uncertainties associated with any variations between interim clinical results and final, the actions and inactions of the FDA, the outcome or timing of regulatory approvals necessary for Atossa, including those necessary to initiate studies of AT-H201, AT-301 and Endoxifen, a lower-than-expected patient enrollment rate, estimated market size of drugs under development, safety and efficacy of Atossa’s products, performance of regulatory bodies, clinical research and investigators, barriers resulting from proprietary rights held by others such as patent rights, whether reduction in Ki-67 or any other outcome of a neoadjuvant study is an approvable endpoint for oral endoxifen, and other risks detailed from time to time in Atossa’s filings with the Securities and Exchange Commission, including, without limitation, its periodic reports on Form 10-K and 10-Q , each as amended and supplemented from time to time.

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Atossa Therapeutics, Inc.
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