8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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): August 5, 2025

Windtree Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (215) 488-9300

Not Applicable

(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:

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

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 7.01 Regulation FD Disclosure.

On August 5, 2025, Windtree Therapeutics, Inc. (the “Company”) issued a press release announcing its interim data of the SEISMiC C Phase 2 study. 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 contained in this Item 7.01 (including Exhibit 99.1) is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section and shall not be deemed to be incorporated by reference in any filing under the Securities Act or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

Cautionary Language Concerning Forward-Looking Statements.

This Current Report on Form 8-K contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 with respect to the term sheets and other related matters. Forward-looking statements are predictions, projections and other statements about future events that are based on current expectations and assumptions and, as a result, are subject to risks and uncertainties. These forward-looking statements are based upon the Company’s and its management’s current expectations, assumptions, estimates, projections and beliefs. Such statements include, but are not limited to, statements regarding the success of the SEISMiC C Study, the ability to move istaroxime to a global Phase 3 program and risks related to the Company’s ability to manage costs and execute on its operational and budget plans. These statements involve known and unknown risks, uncertainties and other factors that may cause actual results or achievements to be materially different and adverse from those expressed in, or implied by, these forward-looking statements. Other risks relating to the Company’s business, including risks that could cause results to differ materially from those projected in the forward-looking statements in this Current Report, the Company’s latest Annual Report on Form 10-K, subsequent Quarterly Reports on Form 10-Q and/or Current Reports on Form 8-K filings with the United States Securities and Exchange Commission, especially under the heading “Risk Factors.” The forward-looking statements in this Current Report speak only as of this date, and the Company disclaims any intent or obligation to revise or update publicly any forward-looking statement except as required by law.

(d) Exhibits

The following exhibits are being filed herewith:

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, thereunto duly authorized.

Date: August 5, 2025

ex_848198.htm

Exhibit 99.1

Windtree Announces Istaroxime Phase 2 Interim Analysis in SCAI Stage C Cardiogenic Shock Patients

Istaroxime was added to currently available inotropes and vasopressors in the study - no new safety signals were identified and physiological improvements were consistent with istaroxime responses in previous trials

Cardiogenic shock is a severe presentation of heart failure and SCAI Stage C patients have low blood pressure and signs of organ damage due to low blood flow

These data provide the Company confidence to move forward with a global Phase 3 trial

WARRINGTON, PA – August 5, 2025 – Windtree Therapeutics, Inc. (“Windtree” or the “Company”) (NasdaqCM: WINT), a diversified company with several divisions, including a cryptocurrency treasury strategy and two promising therapeutic pipelines for which the Company is actively seeking long-term development partners, has performed a planned interim analysis of the SEISMiC C Phase 2 study data evaluating istaroxime in SCAI Stage C cardiogenic shock which showed istaroxime had a similar profile to that seen in previous studies despite a greater severity of illness and being used in addition to currently available inotropes and vasopressors.

The SEISMiC C Study is a global trial including sites in the U.S., Europe and Latin America. It is placebo-controlled, double-blinded study with istaroxime being added to current standard of care, including inotropes or vasopressors in patients with more severe cardiogenic shock (SCAI stage C) than has been studied previously. The study follows the results of the SEISMIC B study where istaroxime was shown to improve blood pressure and hemodynamic variables such as cardiac output (the amount of blood pumped by the heart per minute), reduced filling pressures in the heart and improved signs of organ perfusion such as mixed venous oxygenation in patients with milder cardiogenic shock (SCAI stage B). This data is contributing to a very unique profile of istaroxime in acute decompensated heart failure across severity of illness. Inotropes and vasopressors agents are given to many patients in intensive care units in the USA every year and the results of the SEISMIC program may suggest potential advantages to istaroxime over existing therapies in efficacy and possibly safety. The SESIMIC C study was designed to assess the effects of istaroxime in patients with SCAI Stage C cardiogenic shock (i.e., more severe cardiogenic shock than patients enrolled in previous acute heart failure and cardiogenic shock studies in the past). Many patients in SESIMIC C were treated at the time of enrollment with vasopressors or inotropes and hence the SESIMIC C study is testing for the first time the safety and efficacy of istaroxime in more severe cardiogenic shock when istaroxime treatment is combined with other therapies for cardiogenic shock.

The interim analysis included the first 20 patients enrolled in the study. There were no new safety concerns identified, and no apparent excess arrythmias in patients treated with istaroxime when given with standard of care therapies. The effects on hemodynamic and echocardiographic measures appeared to be consistent with results seen in previous istaroxime studies.

“The results of the SEISMIC C interim analysis are exciting,” said Jed Latkin, Chief Executive Officer of Windtree. “We believe these data will be instrumental in moving istaroxime to a global Phase 3 program in heart failure and cardiogenic shock. Steve Simonson, Chief Medical Officer added, “The interim data are consistent with the previous clinical study results seen in patients with AHF and less severe forms of cardiogenic shock. These data are encouraging for the potential of istaroxime to be effective across the spectrum of cardiogenic shock due to AHF with or without other inotropic or vasopressor drugs.”

About Istaroxime

Istaroxime is a first-in-class dual-mechanism therapy designed to improve both systolic and diastolic cardiac function. Istaroxime is a positive inotropic agent that increases myocardial contractility through inhibition of Na+/K+- ATPase with a complimentary mechanism that facilitates myocardial relaxation through activation of the SERCA2a calcium pump on the sarcoplasmic reticulum enhancing calcium reuptake from the cytoplasm. Data from multiple Phase 2 studies in patients with early cardiogenic shock or acute decompensated heart failure demonstrate that istaroxime infused intravenously can significantly improve cardiac function and blood pressure without increasing heart rate or the incidence of clinically significant cardiac rhythm disturbances.

About Windtree Therapeutics, Inc.

Windtree Therapeutics, Inc. is a diversified company with several divisions, including a cryptocurrency treasury strategy and two promising therapeutic pipelines for which the Company is actively seeking long-term development partners.

Forward Looking Statements

The Company may, in some cases, use terms such as “predicts,” “believes,” “potential,” “proposed,” “continue,” “estimates,” “anticipates,” “expects,” “plans,” “intends,” “may,” “could,” “might,” “will,” “should,” or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. Such statements are based on information available to the Company as of the date of this press release and are subject to numerous important factors, risks, and uncertainties that may cause actual events or results to differ materially from the Company’s current expectations. Examples of such risks and uncertainties include, among other things: the success of the SEISMiC C Study, the ability to move istaroxime to a global Phase 3 program and risks related to the Company’s ability to manage costs and execute on its operational and budget plans. These and other risks are described in the Company’s periodic reports, including its Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, filed with or furnished to the Securities and Exchange Commission and available at www.sec.gov. Any forward-looking statements that the Company makes in this press release speak only as of the date of this press release. The Company assumes no obligation to update forward-looking statements whether as a result of new information, future events, or otherwise, after the date of this press release.

Contact Information:

Eric Curtis

ecurtis@windtreetx.com