You May Vote Your Proxy When You View The Materials On The Internet. You Will Be Asked To Follow The Prompts To Vote Your Shares. LEAP THERAPEUTICS, INC. 47 Thorndike Street Suite B1-1 Cambridge, MA 02141 NOTICE OF ANNUAL MEETING OF STOCKHOLDERS to be held on June 16, 2022 *Stockholders are cordially invited to attend the Virtual Annual Meeting and to vote on the Internet or any Mobile device. Dear Shareholder, The 2022 Annual Meeting of Stockholders of Leap Therapeutics, Inc. will be conducted virtually over the Internet. You will be able to attend the annual meeting, vote your shares electronically and submit your questions during the live webcast of the meeting being held on Thursday, June 16, 2022, at 11:30 AM (local time) by visiting: https://www.cstproxy.com/leaptx/2022. Proposals to be considered at the Annual Meeting: (1)  To consider and act upon a proposal to elect to the Company’s Board of Directors two persons nominated by the Board of Directors; (2) To approve the Leap Therapeutics, Inc. 2022 Equity Incentive Plan (3)  To consider and act upon a proposal to ratify the appointment of EisnerAmper LLP as the Company’s independent registered public accounting firm for the 2022 year, ending December 31, 2022; and (4)  To address such other matters as may properly come before the 2022 Annual Meeting or any adjournment or postponement thereof. The Board of Directors recommends a vote “FOR” all nominees under Proposal 1 and “FOR” Proposals 2 and 3. Your electronic vote authorizes the named proxies to vote your shares in the same manner as if you marked, signed, dated, and returned the proxy card. Vote Your Proxy on the Internet: Go to http://www.cstproxyvote.com Have your notice available when you access the above website. Follow the prompts to vote your shares. To view the Proxy Materials and attend the annual meeting, please go to: https://www.cstproxy.com/leaptx/2022 CONTROL NUMBER LEAP THERAPEUTICS, INC. c/o Continental Proxy Services 1 State Street, New York NY 10004 20157_Leap Therapeutics Proxy Notice Front Vote at the Meeting – If you plan to attend the virtual online annual meeting, you will need your 12 digit control number to vote electronically at the annual meeting. To attend: https://www.cstproxy.com/leaptx/2022

LEAP THERAPEUTICS, INC. 47 Thorndike Street Suite B1-1 Cambridge, MA 02141 Important Notice Regarding the Availability of Proxy Materials For the 2022 Annual Meeting of Stockholders to be Held On June 16, 2022 The following Proxy Materials are available to you to review at: https://www.cstproxy.com/leaptx/2022 - the Company’s Annual Report for the year ended December 31, 2021. - the Company’s 2022 Proxy Statement. - the Proxy Card. - any amendments to the foregoing materials that are required to be furnished to stockholders. This is not a ballot. You cannot use this notice to vote your shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. If you would like to receive a paper or e-mail copy of these documents, you must request one. There is no charge for such documents to be mailed to you. Please make your request for a copy as instructed below on or before May 15, 2022 to facilitate a timely delivery. You may also request that you receive paper copies of all future proxy materials from the Company. ACCESSING YOUR PROXY MATERIALS ONLINE Have this notice available when you request a paper copy of the proxy materials or to vote your proxy electronically. You must reference your Control number. REQUESTING A PAPER COPY OF THE PROXY MATERIALS By telephone please call 917-262-2373, or By logging on to https://www.cstproxy.com/leaptx/2022 or By email at: proxy@continentalstock.com Please include the company name and your control number in the subject line. 20157_Leap Therapeutics Proxy Notice Back