LEAP THERAPEUTICS INC

The information set forth below is included herein for the purpose of providing the disclosure required under “Item 2.05 Costs Associated with Exit or Disposal Activities.” of Form 8-K.

On May 6, 2025, our board of directors approved a restructuring to reduce cash burn and to prioritize clinical development of sirexatamab in CRC and advancing FL-501 in preclinical development. In connection with this restructuring, we reduced our workforce by 13 full-time employees and converted 3 full-time employees to part-time status, in addition to the 11 full-time employees who have departed since the end of the first quarter, resulting in approximately 50% reduction in headcount. We expect to incur one-time costs of approximately $0.35 million to $0.45 million in connection with the overall workforce reduction. The majority of these costs will be recognized in the second quarter of 2025. These costs consist primarily of cash expenditures related to one-time termination benefits (some of which are paid over a number of months), including severance. The estimate of costs that we expect to

incur and the timing thereof are subject to a number of assumptions, and actual results may differ materially. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the actions described above.

(c) Rule 10b5-1 Trading Plan

During the three months ended March 31, 2025, no director or officer of the Company adopted orterminated a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K.