ATOS

EX-99.1

2 atos-ex99_1.htm

EX-99.1

EX-99.1

Atossa Therapeutics Reports Second Quarter 2026 Financial Results and Provides a Corporate Update

SEATTLE, WASHINGTON, August 7, 2026 — Atossa Therapeutics, Inc. (Nasdaq: ATOS) (Atossa or the Company), a clinical-stage biopharmaceutical company developing novel therapies in oncology and other areas of high unmet clinical need, today announced its financial results and provided an update on recent corporate developments for the second quarter ended June 30, 2026.

“During the quarter, we executed well across the business,” stated Dr. Steven Quay, M.D., Ph.D., Atossa Therapeutics’ President and Chief Executive Officer. “We continued to advance the scientific rationale for (Z)-endoxifen’s potential in rare pediatric diseases, such as Duchenne Muscular Dystrophy and McCune-Albright Syndrome, while also strengthening its clinical and scientific foundation in breast cancer, all through new data presented at important industry conferences, including ASCO and AACR, as well as publications in well-regarded peer-reviewed journals, Degenerative Neurological and Neuromuscular Disease and npj Breast Cancer.”

Dr. Quay continued, “These accomplishments, together with additional capital from our registered direct offering, underscore the breadth of potential we see for (Z)-endoxifen, and investors’ support in our ability to continue advancing our programs.”

Second Quarter 2026 & Recent Highlights

Rare Diseases

• Atossa Participated at the 2026 American Association for Cancer Research (AACR) Special Conference in Cancer Research: Cancer Evolution

o In a poster presentation titled, “Dual estrogen receptor and PKC-β signaling modulation by (Z)-Endoxifen: A mechanism-driven therapeutic strategy for estrogen-driven pathology in McCune-Albright Syndrome,” the Company discussed a dual mechanism of action for (Z)-endoxifen in estrogen-driven pathology relevant to McCune-Albright Syndrome-associated Peripheral Precocious Puberty (MAS-PPP).

o The dual mechanism includes the blockade of estrogen receptor (ER)-mediated transcription downstream of autonomous estrogen production and suppression of PKC-β/AKT-associated proliferative and cell-cycle signaling.

o This multi-pathway profile may address a key therapeutic gap in MAS-PPP, where estrogen suppression alone may not fully mitigate downstream proliferative signaling.

o The Company previously received Rare Pediatric Disease (RPD) designation for (Z)-endoxifen from the U.S. Food and Drug Administration (FDA) for (Z)-endoxifen for the treatment of McCune-Albright Syndrome (MAS).

• The Company Announced Acceptance of Manuscript Highlighting the Utrophin-Modulation Potential of (Z)-Endoxifen in Duchenne Muscular Dystrophy (DMD)

o A paper details how (Z)-endoxifen may support the expression of utrophin, a paralog of dystrophin. (Z)-Endoxifen therefore represents a potential dystrophin mutation-agnostic treatment for DMD. The paper citation is: Remmel HL, Hammer SS, Blackburn SM, Quay SC. (Z)-Endoxifen as a Potential Modulator of Utrophin Pathways in Duchenne Muscular Dystrophy: A Mechanistic and Transcriptomic Perspective. Degener Neurol Neuromuscular Dis. 2026;16:574524 https://doi.org/10.2147/DNND.S574524

o The results support further investigation of (Z)-endoxifen in dystrophin-deficient models, as well as biomarker development. These data also build upon the Company’s previously published manuscript, “A Hypothesized Therapeutic Role of (Z)-Endoxifen in Duchenne Muscular Dystrophy,” also published in Degenerative Neurological and Neuromuscular Disease.

o The Company previously received Orphan Drug Designation (ODD) and RPD designation for (Z)-endoxifen from the FDA for the treatment of DMD.

Oncology

• The Company Published Manuscript Highlighting the Anti-cancer Activity of (Z)-Endoxifen-related Compounds

o In the peer-reviewed journal, npj Breast Cancer, the Company published an article titled, “Novel (Z)-endoxifen-related new chemical entities exhibit potent anti-cancer activity in ERα+ breast cancer.”

o The investigators evaluated five previously uncharacterized compounds generated during the synthesis of (Z)-endoxifen, alongside (Z)-endoxifen in a broad panel of laboratory assays, as well as in combination with the CDK4/6 inhibitor abemaciclib.

o The publication reported anti-estrogenic and anti-cancer activity across multiple ER-positive (ER+) breast cancer models, including models harboring clinically relevant activating mutations in ESR1.

o In certain experimental settings and models, selected compounds combined with abemaciclib demonstrated additive to synergistic activity that was comparable to or greater than the activity observed with abemaciclib plus (Z)-endoxifen.

o The authors concluded that select compounds warrant further in vivo safety evaluation, as well as efficacy studies, including as potential second- or third-line approaches for recurrent disease.

• Atossa Participated in the 2026 American Society o

8-K

0001488039False00014880392026-01-092026-01-09

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 9, 2026

Atossa Therapeutics, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware

001-35610

26-4753208

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

1448 NW Market Street, Suite 500

Seattle, Washington

98107

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s Telephone Number, Including Area Code: (206) 588-0256

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check th e appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.18 par value

ATOS

The Nasdaq Capital Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition

On January 9, 2026, Atossa Therapeutics, Inc. (the “Company”) made available an updated corporate presentation, which is attached to this Current Report on Form 8-K (the “Form 8-K”) as Exhibit 99.1 (the “Corporate Presentation”), that estimated that the Company had cash and cash equivalents of approximately $40 million as of December 31, 2025.

The information contained in Item 2.02 of this Form 8-K and in Exhibit 99.1 attached hereto regarding the Company’s estimated cash and cash equivalents balance as of December 31, 2025 is preliminary, unaudited and subject to finalization of its full financial results and completion of the Company’s financial statement closing procedures for the fourth quarter and fiscal year ended December 31, 2025. This estimate also does not present all information necessary for an understanding of the Company’s financial condition as of December 31, 2025 and its results of operations for the year ended December 31, 2025. Accordingly, undue reliance should not be placed on this preliminary estimate.

Item 7.01 Regulation FD Disclosure

The Corporate Presentation, which is attached to this Form 8-K as Exhibit 99.1, is incorporated into this Item 7.01 by reference.

The information in this Form 8-K, including Exhibit 99.1 attached hereto, shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of Section 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained herein and in the accompanying exhibit shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission (the “SEC”) made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing. . Cautionary Note Regarding Forward-Looking Statements

This Form 8-K contains certain “forward-looking statements” within the meaning of applicable securities laws, including but not limited to, our expectations regarding the Company’s development and regulatory strategy and related milestones, the potential indications that the Company may pursue for (Z)-Endoxifen, the potential for (Z)-Endoxifen to receive regulatory approval and the timing thereof, the potential market and growth opportunities for the Company and the Company’s estimated cash and cash equivalents and its expectations related thereto. Words such as “expect,” “potential,” “continue,” “may,” “will,” “should,” “could,” “would,” “seek,” “intend,” “plan,” “estimate,” “anticipate,” “believe,” “design,” “predict,” “future,” or other similar expressions or statements regarding intent, belief or current expectations, are forward-looking statements.

Forward-looking statements in this Form 8-K are subject to risks and uncertainties that may cause actual results, outcomes, or the timi

8-K

false000148803900014880392025-11-122025-11-12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 12, 2025

Atossa Therapeutics, Inc. (Exact name of Registrant as Specified in Its Charter)

Delaware

001-35610

26-4753208

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

10202 5th Avenue NE, Suite 200

Seattle, Washington

98125

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s Telephone Number, Including Area Code: (206) 588-0256

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, $0.18 par value

ATOS

The Nasdaq Capital Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02. Results of Operations and Financial Condition.

On November 12, 2025, Atossa Therapeutics, Inc. (the “Company”) issued a press release announcing the quarter ended September 30, 2025 financial results and providing a Company update. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information in Items 2.02 and 9.01 of this report, including Exhibit 99.1 attached hereto, shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained herein and in the accompanying exhibit shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

Item 9.01. Financial Statements and Exhibits. (d) Exhibits

Exhibit No.

Description

99.1

Press Release dated November 12, 2025

104

Cover page Interactive Data File (embedded within the Inline XBRL document)

* * *

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Atossa Therapeutics, Inc.

Date:

November 12, 2025

By:

/s/ Mark J. Daniel

Mark J. Daniel Chief Financial Officer (Principal Financial and Accounting Officer)