Ms. Susan Pietropaolo reports

APTOSE BIOSCIENCES ANNOUNCES UPDATE ON ANTICIPATED TIMING OF CLOSING OF THE PLAN OF ARRANGEMENT WITH HANMI PHARMACEUTICAL

Aptose Biosciences Inc.'s closing of the previously announced arrangement with Hanmi Pharmaceutical Co. Ltd. and HS North America Ltd., a wholly owned subsidiary of Hanmi, has been delayed as certain Korean regulatory approvals pertaining to the arrangement remain in progress. The parties do not anticipate that the review will prevent closing and continue to work toward completing the arrangement that they now target for the month of May. The company will provide a further update when available.

Transaction details

As previously disclosed in the company's news release dated Nov. 19, 2025, upon the completion of the arrangement, Hanmi will acquire all of the issued and outstanding common shares of Aptose that are not currently owned or controlled by the Hanmi purchasers or their respective affiliates and shareholders of Aptose, other than the Hanmi purchasers and their respective affiliates that hold any common shares, will receive $2.41 in cash per common share, which represents a premium of 28 per cent over Aptose's 30-day VWAP (volume-weighted average price) of $1.88 on the Toronto Stock Exchange for the period immediately preceding entering into the arrangement agreement.

About Aptose Biosciences Inc.

Aptose Biosciences is a clinical-stage biotechnology company committed to developing precision medicines addressing unmet medical needs in oncology, with an initial focus on hematology. The company's small molecule cancer therapeutics pipeline includes products designed to provide single agent efficacy and to enhance the efficacy of other anti-cancer therapies and regimens without overlapping toxicities. The company's lead clinical-stage compound TUS is an oral kinase inhibitor that has demonstrated activity as a monotherapy and in combination therapy in patients with relapsed or refractory AML and is being developed as a front-line triplet therapy in newly diagnosed AML.

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