Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS and OTC: APTOF), a clinical-stage precision oncology company developing a tuspetinib (TUS)-based triple drug frontline therapy to treat patients with newly diagnosed acute myeloid leukemia (AML), today announced the closing of the plan of arrangement (announced on November 19, 2025 and February 24, 2026) pursuant to which HS North America Ltd. (the “Purchaser”), a wholly owned subsidiary of Hanmi Pharmaceutical Co. Ltd. (“Hanmi”, and together with the Purchaser, the “Hanmi Purchasers”) acquired all of the issued and outstanding common shares of Aptose (the “Common Shares”) that were not currently owned or controlled by the Hanmi Purchasers or their respective affiliates (the “Arrangement”).

Under the terms of the amended and restated arrangement agreement among Aptose and the Hanmi Purchasers dated February 23, 2026, Aptose shareholders, other than the Hanmi Purchasers and their respective affiliates that hold any Common Shares, will receive C$2.41 in cash per Common Share, which represents a premium of 28% over Aptose’s 30-day VWAP of C$1.88 on the Toronto Stock Exchange (“TSX”) for the period immediately preceding entering into the Arrangement Agreement.

The Arrangement received approval from the Company’s shareholders at a special meeting held on March 31, 2026, and the Arrangement received final court approval on the same date. The Arrangement has also received the necessary regulatory approvals in Korea.

As a result of the Arrangement, the Common Shares are expected to be delisted from the TSX at the close of trading on or about July 3, 2026. The Company has submitted an application to cease to be a reporting issuer under applicable Canadian securities laws and to otherwise terminate the Company’s public reporting requirements in the United States and Canada.