Aptose leases office space in San Diego, California and Toronto, Canada. The lease for the San Diego office space was scheduled to expire on March 31, 2023. On November 4, 2022, this lease was extended through May 31, 2026 (the "Third Amendment"). Management has determined that the Third Amendment represents a lease modification, as defined by ASC 842, Leases, does not meet the requirements for accounting as a separate contract and continues to meet the definition of an operating lease. Accordingly, the Company has accounted for the Third Amendment prospectively, via remeasurements, on the Modification Date, to the lease liability and corresponding right-of-use asset. Aptose previously leased lab space in San Diego, which we exited prior to the expiration of the lease on February 28, 2023. The costs incurred in exiting this laboratory space were not material. We lease office space in Toronto, Ontario, Canada, with this lease previously scheduled to expire on June 30, 2023. This lease was extended for one year on February 23, 2023, with this extension expiring on June 30, 2024. The Company has not included any extension periods in calculating its right-to-use assets and lease liabilities. The Company also enters into leases for small office equipment.

To calculate the lease liability, the lease payments in the table above were discounted over the remaining term of the leases using the Company’s incremental borrowing rate as of January 1, 2019 for existing leases at the time of adopting ASC 842, and for new leases after the date adoption, as of the date of the execution date of the new lease. The following table presents the weighted average remaining term of the leases and the weighted average discount rate: