Ms. Susan Pietropaolo reports

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

Closing of Aptose Biosciences Inc.'s previously announced arrangement with Hanmi Pharmaceutical Co. Ltd. and HS North America Ltd., a wholly owned subsidiary of Hanmi, has been further 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 June. The company will provide a further update when available.

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.

The company also announced that it has received an additional advance of $2-million (U.S.) from Hanmi as part of a $11.9-million (U.S.) loan amended facility agreement announced prior on Sept. 22, 2025. To date, Aptose has received an aggregate of $9.9-million (U.S.) under the facility agreement. Aptose expects to receive the final advance of $2-million (U.S.) under the facility agreement in the coming days. These advances support Aptose and enable uninterrupted continuance of the Tuscany clinical trial with tuspetinib in combination with venetoclax and azacitidine for the front-line treatment of newly diagnosed AML (acute myeloid leukemia).

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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