Aptose Biosciences, Inc.

SAN DIEGO and TORONTO, June 20, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. ("Aptose" or the "Company") (TSX: APS; 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 that it has entered into a new loan agreement (the “Loan Agreement”) with Hanmi Pharmaceutical Co. Ltd. (“Hanmi”). The Loan Agreement is an uncommitted facility for up to US$8.5million, administered through multiple advances for the purpose of continued clinical development of TUS. The Loan Agreement constitutes a “related-party transaction” within the meaning of Multilateral Instrument 61-101 – Protection of Minority Security Holders in Special Transactions (“MI 61-101”) as Hanmi is a related party of the Company under Canadian securities laws. However, the Company is relying on the exemption from the formal valuation and minority shareholder approval requirements contained in MI 61-101 on the basis of the “financial hardship” exemption therein. “Aptose is incredibly grateful for Hanmi’s continued support tuspetinib,” said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer of Aptose. “Our data to date in the TUS+VEN+AZA triplet reveal promising antileukemic activity and safety across diverse AML populations – some with the greatest unmet needs.” Tuspetinib is a convenient once daily oral agent that potently targets SYK, mutated and wild type forms of FLT3, mutated KIT, JAK1/2, and RSK2 kinases, while avoiding many typical toxicity concerns observed with other agents. The ongoing TUSCANY triplet Phase 1/2 study is designed to test various doses and schedules of TUS in combination with standard dosing of azacitidine and venetoclax in newly diagnosed patients with AML who are ineligible to receive induction chemotherapy. Aptose recently reported early data from the first two dose cohorts that have demonstrated safety, CRs and minimal residual disease (MRD) negativity across patients with diverse mutations (press release here). About Aptose 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 tuspetinib (TUS), is an oral kinase inhibitor that has demonstrated activity as a monotherapy and in combination therapy in patients with relapsed or refractory acute myeloid leukemia (AML) and is being developed as a frontline triplet therapy in newly diagnosed AML. For more information, please visit www.aptose.com. Forward Looking Statements This press release may contain forward-looking statements within the meaning of Canadian and U.S. securities laws, including statements relating but not limited to, the use of proceeds of the Loan Facility Agreement, the development of tuspetinib, the timing of the first advance under the Loan Facility Agreement, and statements relating to the Company’s plans, objectives, expectations and intentions and other statements including words such as “continue”, “expect”, “intend”, “will”, “should”, “would”, “may”, and other similar expressions. Such statements reflect our current views with respect to future events and are subject to risks and uncertainties and are necessarily based upon a number of estimates and assumptions that, while considered reasonable by us are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors could cause our actual results, performance or achievements to be materially different from any future results, performance or achievements described in this press release. Such factors could include, among others: our ability to negotiate a collaboration agreement to jointly develop tuspetinib with Hanmi, our ability to remain compliant with Nasdaq listing requirements and other risks detailed from time-to-time in our ongoing quarterly filings, annual information forms, annual reports and annual filings with Canadian securities regulators and the United States Securities and Exchange Commission. Should one or more of these risks or uncertainties materialize, or should the assumptions set out in the section entitled "Risk Factors" in our filings with Canadian securities regulators and the United States Securities and Exchange Commission underlying those forward-looking statements prove incorrect, actual results may vary materially from those described herein. These forward-looking statements are made as of the date of this press release and we do not intend, and do not assume any obligation, to update these forward-looking statements, except as required by law. We cannot assure you that such statements will prove to be accurate as actual results and future events could differ materially from those anticipated in such statements. Investors are cautioned that forward-looking statements are not guarantees of future performance and accordingly investors are cautioned not to put undue reliance on forward-looking statements due to the inherent uncertainty therein. For further information, please contact: Aptose Biosciences Inc. Susan Pietropaolo Corporate Communications & Investor Relations 201-923-2049 spietropaolo@aptose.com

The money will be used to pay Aptose Biosciences’ staff as well as continue the development of tuspetinib.\n Aptose Biosciences has been thrown a financial lifeline by its own CEO while the leukemia-focused biotech scrambles around for cash to prevent the company from going bust.The Canadian biotech, whose lead clinical-stage asset is an oral kinase inhibitor called tuspetinib, revealed that its CEO and Chairman William Rice, Ph.D., had provided a “short-term cash advance … to support near-term obligations … while it engages in ongoing negotiations with prospective funding partners.”“The advance is non-interest bearing and the company may repay the advance in whole or in part with no penalty at any time and from time to time,” Aptose explained in a June 17 release.The money will be used to pay the company’s staff as well as continue the development of tuspetinib, which is being evaluated in a phase 1/2 study for acute myeloid leukemia (AML) in combination with venetoclax and azacitidine.Despite the cash infusion, Aptose warned that if the company doesn’t find more “in the coming days … the corporation does not expect to have sufficient financial resources to fund planned company operations and will have certain alternatives that could include insolvency proceedings.” The Toronto-based biotech ended March with $4.7 million in the bank, which it had only expected to fund its R&D costs through to the end of May 2025.Last week, Aptose presented data from the trial of tuspetinib that it claimed showed “exciting activity.” This included all three of the AML patients who received the 80 mg dose of the drug achieving composite complete remissions.

Announces short-term cash advance SAN DIEGO and TORONTO, June 17, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS; OTC: APTOF), a clinical-stage precision oncology company, announced today that the Company has secured a short-term cash advance from Dr. William G. Rice, the Company’s Chairman of the Board, President and Chief Executive Officer (the “Advance”), to support near-term obligations, including payroll, and to enable continued advancement of its clinical-stage oral kinase inhibitor, tuspetinib, while it engages in ongoing negotiations with prospective funding partners. The Advance is non-interest bearing and the Company may repay the Advance in whole or in part with no penalty at any time and from time to time. The Advance is unsecured, and no securities will be issued in connection with the Advance. The Advance constitutes a “related-party transaction” within the meaning of Multilateral Instrument 61-101 – Protection of Minority Security Holders in Special Transactions (“MI 61-101”) as Dr. Rice is a related party of the Company under Canadian securities laws. However, the Company is relying on the exemptions from the formal valuation and minority shareholder approval requirements contained in MI 61-101. Despite this advance, if Aptose does not receive additional funding in the coming days, the Corporation does not expect to have sufficient financial resources to fund planned Company operation and will have certain alternatives that could include insolvency proceedings. Announces board resignation Separately, Aptose announced that effective June 16, 2025, Ms. Carol Ashe has resigned as a director of the Company. The Company wishes to thank Ms. Ashe for her valuable contributions during her tenure as an Aptose board member and wishes her every success in her future endeavors. About Aptose 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 lead clinical-stage, oral kinase inhibitor tuspetinib (TUS) has demonstrated activity as a monotherapy and in combination therapy in patients with relapsed or refractory acute myeloid leukemia (AML) and is being developed as a frontline triplet therapy in newly diagnosed AML. For more information, please visit www.aptose.com. Forward Looking Statements This press release may contain forward-looking statements within the meaning of Canadian and U.S. securities laws, including, but not limited to, statements relating to the terms of the Advance, including the purpose of the Advance, expectations with respect to the repayment of the Advance, as well as statements relating to the Company’s plans, objectives, expectations and intentions and other statements including words such as “continue”, “expect”, “intend”, “will”, “should”, “would”, “may”, and other similar expressions. Such statements reflect our current views with respect to future events and are subject to risks and uncertainties and are necessarily based upon a number of estimates and assumptions that, while considered reasonable by us are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. These risks and uncertainties include, among others: our ability to obtain the capital required for research and operations and to continue as a going concern; the inherent risks in early stage drug development including demonstrating efficacy; development time/cost and the regulatory approval process; the progress of our clinical trials; our ability to find and enter into agreements with potential partners; our ability to attract and retain key personnel; changing market conditions; inability of new manufacturers to produce acceptable batches of GMP in sufficient quantities; unexpected manufacturing defects; and other risks detailed from time-to-time in our ongoing quarterly filings, annual information forms, annual reports and annual filings with Canadian securities regulators and the United States Securities and Exchange Commission. Should one or more of these risks or uncertainties materialize, or should the assumptions set out in the section entitled “Risk Factors” in our filings with Canadian securities regulators and the United States Securities and Exchange Commission underlying those forward-looking statements prove incorrect, actual results may vary materially from those described herein. These forward-looking statements are made as of the date of this press release and we do not intend, and do not assume any obligation, to update these forward-looking statements, except as required by law. We cannot assure you that such statements will prove to be accurate as actual results and future events could differ materially from those anticipated in such statements. Investors are cautioned that forward-looking statements are not guarantees of future performance and accordingly investors are cautioned not to put undue reliance on forward-looking statements due to the inherent uncertainty therein. For further information, please contact Aptose Biosciences Inc.Susan PietropaoloCorporate Communications & Investor Relations201-923-2049spietropaolo@aptose.com