Exhibit 99.1

Atossa Therapeutics Announces Full Year 2024 Financial Results and Provides

Corporate Update

Ended 2024 with $71.1 million of cash and cash equivalents and no debt

Conference Call and Webcast Scheduled for Tuesday, March 25, 2025, at 8:30 a.m. Eastern Time

SEATTLE, March 25, 2025 -- Atossa Therapeutics, Inc. (Nasdaq: ATOS) (“Atossa” or the “Company”), a clinical-stage biopharmaceutical company developing innovative medicines for breast cancer, today announced its financial results for the full year ended December 31, 2024 and provided an update on recent company developments.

Fourth Quarter and Early 2025 Highlights

“Metastatic breast cancer remains an area of critical unmet need, where improved therapies are urgently required,” said Steven Quay, M.D., Ph.D., President and Chief Executive Officer of Atossa. “(Z)-endoxifenhas demonstrated promising anti-estrogenic and anti-tumor effects alongside a favorable tolerability profile, which we believe positions it as a potential next-generation therapy. We believe that pursuing an initial approval in metastatic breast cancer could offer a more efficient regulatory pathway, potentially enabling us to make (Z)-endoxifen available sooner to the patients who need it most. We also believe this strategy further supports our ability to expand the broader potential of (Z)-endoxifen to address multiple stages of breast cancer, from reducing tumor growth to preventing recurrence after successful treatment.”

Conference Call Information:

The webcast will be available at the investor relations section of the Company'swebsite at atossatherapeutics.com. Alternatively, to access the conference call by telephone, U.S.-based callers should dial 1-800-836-8184 and international listeners should dial 1-646-357-8785. All listeners should provide the operator with the conference call name "Atossa Therapeutics Business Update" to join.

Following the conclusion of the conference call, a replay will be available for 30 days on the investor relations section of the Company's website at atossatherapeutics.com.

Comparison of Years Ended December 31, 2024 and 2023

Operating Expenses. Total operating expenses were $27.6 million for the year ended December 31, 2024, which was a decrease of $3.8 million, from the year ended December 31, 2023 of $31.4 million. Factors contributing to the decreased operating expenses in the year ended December 31, 2024 are explained below.

Research & Development (R&D) Expenses. The following table provides a breakdown of major categories within R&D expenses for the years ended December 31, 2024 and 2023, together with the dollar change in those categories (dollars in thousands):

General and Administrative (G&A) Expenses. The following table provides a breakdown of major categories within G&A expenses for the years ended December 31, 2024 and 2023, together with the dollar change in those categories (dollars in thousands):

Interest Income. Interest income of $4.1 million for the year ended December 31, 2024 represented a decrease of $0.2 million compared to the prior year and was primarily due to a decrease in funds invested in the money market account.

Impairment Charge on Investment in Equity Securities. For the years ended December 31, 2024 and 2023, we wrote down our investment in equity securities by $1.7 million and $3.0 million, respectively, due to impairment of our investment in Dynamic Cell Therapies, Inc.

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 in four Phase 2 trials: one in women diagnosed with ductal carcinoma in situ, and three other studies including the EVANGELINE study and two I-SPY studies in women with ER+/HER2- breast cancer. Atossa’s (Z)-endoxifen is protected by three issued U.S. patents and numerous pending patent applications.

About Atossa Therapeutics

Atossa Therapeutics, Inc. (Nasdaq: ATOS) is a clinical-stage biopharmaceutical company dedicated to transforming breast cancer treatment through innovative science and patient-focused solutions. The company’s lead product candidate, (Z)-endoxifen, is a highly potent SERM designed for use across the breast cancer spectrum, including prevention, neoadjuvant, adjuvant, and metastatic settings. Atossa is committed to advancing its robust clinical research programs to improve patient outcomes while creating sustainable value for shareholders. For more information, visit atossatherapeutics.com.

FORWARD LOOKING STATEMENTS

This press release contains certain information that may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. We may identify these forward-looking statements by the use of words such as “expect,” “potential,” “continue,” “may,” “will,” “should,” “could,” “would,” “seek,” “intend,” “plan,” “estimate,” “anticipate,” “believe,” “design,” “predict,” “future,” or other comparable words. All statements made in this press release that are not statements of historical fact, including statements regarding data related to the (Z)-endoxifen program, the safety, tolerability and efficacy of (Z)-endoxifen, the potential of (Z)-endoxifen as a breast cancer prevention and treatment agent, the potential indications that the Company may pursue for (Z)-endoxifen, the potential for (Z)-endoxifen to receive regulatory approval, benefits of the Company’s strategy of pursuing a metastatic indication for (Z)-endoxifen, the expected design and enrollment of trials and timing of data and related publications, and the potential market and growth opportunities for the Company, are forward-looking statements. Forward-looking statements in this press release are subject to risks and uncertainties that may cause actual results, outcomes, or the timing of actual results or outcomes, to differ materially from those projected or anticipated, including risks and uncertainties associated with: our ability to obtain patent coverage for our product candidates; macroeconomic conditions and increasing geopolitical instability; the expected timing of releasing data; any variation between interim or preliminary and final clinical results or analysis; actions and inactions by the FDA and foreign regulatory bodies; the outcome or timing of regulatory approvals needed by Atossa, including those needed to continue our planned (Z)-endoxifen trials; our ability to satisfy regulatory requirements; our ability to regain compliance or maintain compliance with the continued listing requirements of the Nasdaq Stock Market; our ability to successfully develop and commercialize new therapeutics; the success, costs and timing of our development activities, including our ability to successfully initiate or complete our clinical trials, including our (Z)-endoxifen trials; our anticipated rate of patient enrollment; our ability to contract with third-parties and their ability to perform adequately; our estimates on the size and characteristics of our potential markets; our ability to successfully defend litigation and other similar complaints and to establish and maintain intellectual property rights covering our products; whether we can successfully complete our clinical trial of oral (Z)-endoxifen in women with mammographic breast density and our trials of (Z)-endoxifen in women with breast cancer, and whether the studies will meet their objectives; our expectations as to future financial performance, expense levels and capital sources, including our ability to raise capital; our ability to attract and retain key personnel; our anticipated working capital needs and expectations around the sufficiency of our cash reserves; and other risks and uncertainties detailed from time to time in Atossa’s filings with the Securities and Exchange Commission, including without limitation its Annual Reports on Form 10-K and Quarterly Reports on 10-Q. Forward-looking statements are presented as of the date of this press release. Except as required by law, we do not intend to update any forward-looking statements, whether as a result of new information, future events or circumstances or otherwise.

Contact:

Michael Parks
VP, Investor and Public Relations
484-356-7105

michael.parks@atossainc.com

ATOSSA THERAPEUTICS, INC.

CONSOLIDATED BALANCE SHEETS

(amounts in thousands, except share and per share data)

ATOSSA THERAPEUTICS, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(amounts in thousands, except share and per share data)