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): October 20, 2025

Leap Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

Delaware		001-37990		27-4412575
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

47 Thorndike Street, Suite B1-1
Cambridge, MA 02141

(Address of Principal Executive Office) (Zip Code)

(617) 714-0360

(Registrant’s telephone number, including area code)

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, par value $0.001 per share		LPTX		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 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

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 8.01 Other Events.

On October 20, 2025, Leap Therapeutics, Inc. (the “Company”) issued a press release announcing final results from Part B of its DeFianCe study. The final clinical results were presented on behalf of the DeFianCe study investigators by Zev Wainberg, MD, Professor of Medicine and Co-Director of the GI Oncology Program at UCLA in a Mini Oral session at the European Society for Medical Oncology (ESMO) Congress 2025 in Berlin, Germany.

A copy of the news release is filed with this Current Report on Form 8-K as Exhibit 99.1 and incorporated into this Item 8.01 by reference.

9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.		Description
99.1		Press Release, dated October 20, 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.

	LEAP THERAPEUTICS, INC.

Date: October 20, 2025	/s/ Douglas E. Onsi
	Douglas E. Onsi
	President & CEO

LEAP THERAPEUTICS, INC. 8-K