SAN DIEGO and TORONTO, March 31, 2026 (GLOBE NEWSWIRE) -- 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 provided a corporate update and announced the financial results for the year ended December 31, 2025.

“We are pleased that shareholders have approved our proposed arrangement with Hanmi, which enables us to continue and expand the development of the TUS+VEN+AZA triplet, which has shown promising response rates and safety as a mutation agnostic therapy across a diverse population of patients newly diagnosed with AML,” said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer of Aptose. “We are extremely grateful for Hanmi’s ongoing support, including its significant financial support under difficult circumstances over the past two years. The data in our clinical trial continue to support the promise of TUS+VEN+AZA therapy, and we look forward to presenting the next set of data at the EHA2026 Congress in June.”     

Corporate Update

At a special meeting of shareholders today (the “Special Meeting”), Aptose shareholders approved: (i) the continuance of the Company from the Canada Business Corporations Act to the Business Corporations Act (Alberta); and (ii) 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”) will acquire all of the issued and outstanding common shares of Aptose (the “Common Shares”) that are not currently owned or controlled by the Hanmi Purchasers or their respective affiliates (the “Arrangement”). During the past 18 months, Hanmi has singularly supported Aptose and the continued development of tuspetinib (TUS) through debt facilities to Aptose totaling more than US$41 million. 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.

Details of the voting results at the Special Meeting are below:

A report on voting results for the Special Meeting will be filed under the Company’s profile on SEDAR+ at sedarplus.ca.

Aptose is also pleased to announce that the Court of King’s Bench of Alberta has issued a final order approving the Arrangement under the provisions of the ABCA. Closing of the Arrangement remains subject to the satisfaction of certain customary closing conditions, including regulatory approvals. Subject to the satisfaction of these closing conditions, the parties to the Arrangement currently expect the Arrangement to be completed by the end of April, 2026.

Key Corporate Highlights

• Aptose Clinical Data Presented at ASH – Aptose presented clinical data on tuspetinib at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition in Orlando, Florida in December 2025. As reported, in newly diagnosed AML patients, TUS+VEN+AZA demonstrated promising safety, tolerability and resilient efficacy, including MRD-negative remissions across a broad mutational spectrum.
  
  Key highlights and messages from the ASH poster presentation, “TUSCANY Study demonstrates    safety and efficacy of tuspetinib plus standard of care venetoclax and azacitidine in patients with newly diagnosed AML ineligible for induction chemotherapy” :
  
  
  • High-quality clinical responses (CR/CRh):
    • 90% across 40 mg, 80 mg and 120 mg dose levels
    • 100% at the higher 80 mg and 120 mg dose levels
    • Observed in FLT3-WT, FLT3-ITD, and NPM1c genetic subgroups
    • Observed in biallelic TP53/complex karyotype and RAS adverse genetic subgroups
    • Observed in AML with MDS-related mutations
  • MRD negativity: 78% by central flow cytometry in responding subjects
  • TUS targets VEN resistance mechanisms; inhibits kinase-driven abnormal signaling
  • Two subjects transitioned to hematopoietic stem cell transplantation and both returned for TUS maintenance therapy
  • TUS+VEN+AZA triplet therapy was well tolerated with no dose-limiting toxicities (DLTs) across all evaluable TUS dose levels
    • No DLTs including no prolonged myelosuppression for subjects in remission in Cycle 1
    • No drug-related deaths, differentiation syndrome, QTc prolongation, or CPK elevation reported
    • 8/10 evaluable subjects experienced red cell and platelet transfusion independence for > 8 weeks after their best response
    • Febrile neutropenia was reported in 2 subjects (16.7%), with 1 subject related to TUS

At the recently enrolled 160 mg dose level, preliminary findings show patients achieving early blast clearance with MRD-negativity and formal responses in the first few weeks of treatment (not included in poster data cut).

Aptose’s press release is available here. The ASH poster presentation is available here.

Net loss for the year ended December 31, 2025 of $25.5 million increased slightly as compared with a net loss of $25.4 million for the comparable period in 2024. 

• Total cash, cash equivalents, restricted cash and restricted cash equivalents as of December 31, 2025 were $4.1 million. The Company does not have sufficient cash to fund operations and relies on advances made by Hanmi to fund operations. The Company is actively deploying financing and cost reduction efforts to extend cash runway.
  
  
• As of March 16, 2026, there were 2,552,429 Common Shares issued and outstanding. In addition, there were 37,370 Common Shares issuable upon the exercise of outstanding stock options and there were 1,267,585 Common Shares issuable upon the exercise of the outstanding warrants.
  

RESEARCH AND DEVELOPMENT EXPENSES

Research and development expenses for the years ended December 31, 2025 and 2024 were as follows:

Research and development expenses decreased by $3.8 million to $11.3 million for the year ended December 31, 2025 as compared to $15.1 million for the comparable period in 2024. Changes to the components of our research and development expenses presented in the table above are primarily as a result of the following activities:

• Program costs for tuspetinib decreased by $1.7 million to $7.9 million for the year ended December 31, 2025 compared to $9.6 million for the comparable period in 2024. The increased costs associated with the TUSCANY study were offset by a decrease in tuspetinib development expenses during the current year. This reduction is due to the conclusion of activities in our APTIVATE clinical trial during the current year as compared to higher APTIVATE activities during the prior year, as well as lower manufacturing and related development costs.
  
  
• Program costs for luxeptinib decreased by approximately $0.1 million compared to the prior year. This reduction was primarily attributed to lower clinical trial and manufacturing activities.
  
  
• The Company discontinued further development of APTO-253.
  
  
• Personnel-related expenses decreased by $1.8 million to $2.9 million for the year ended December 31, 2025 compared to $4.7 million in the prior year. The decrease was primarily due to lower headcount for research and development personnel in 2025.
  
  
• Stock-based compensation decreased by $0.1 million for the year ended December 31, 2025 compared to the comparable period in 2024. This decrease was primarily due to stock options forfeited and/or vested in prior periods that are no longer being expensed resulting in lower expense in the current year.
  

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 contains forward-looking statements within the meaning of Canadian and U.S. securities laws, including, but not limited to, statements regarding the Company’s clinical development plans, the clinical potential, anti-cancer activity, therapeutic potential and applications and safety profile of tuspetinib, clinical trials, upcoming milestones and presentation of additional data, cost reduction efforts, expectations regarding capital available to the Company to fund planned Company operations, the Company’s cash runway, statements relating to the completion of the Arrangement, including the satisfaction of the closing conditions and the anticipated closing date and statements relating to the Company’s plans, objectives, expectations and intentions and other statements including words such as “continue”, “expect”, “intend”, “will”, “hope”, “should”, “would”, “may”, “potential” 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: risks and uncertainties related to the transactions contemplated by the Arrangement Agreement including but not limited to the possibility that the Arrangement will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise; our ability to obtain the capital required for research and operations; 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 and economic conditions; unexpected manufacturing defects, the evolving regulatory and political landscape and the funding of government programs and other risks detailed from time-to-time in our ongoing current reports, quarterly filings and annual reports.
  
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

Shareholders are Reminded of Voting Deadline for Upcoming Special Meeting

SAN DIEGO and TORONTO, March 23, 2026 (GLOBE NEWSWIRE) --  Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS; OTC: APTOF) is pleased to announce that Glass, Lewis & Co. (“Glass Lewis”), a leading independent proxy advisory firm, has recommended that Aptose shareholders (the “Shareholders”) vote “FOR” a special resolution (the “Arrangement Resolution”) to approve the previously announced arrangement (the “Arrangement”) pursuant to which Hanmi Pharmaceutical Co. Ltd. (“Hanmi”) and HS North America Ltd., a wholly owned subsidiary of Hanmi (“Hanmi Purchaser” and together with Hanmi, the “Hanmi Purchasers”), will acquire all of the issued and outstanding common shares of Aptose (“Common Shares”) that are not currently owned or controlled by the Hanmi Purchasers or their respective affiliates.

Glass Lewis also recommended approval of a continuance that will result in the Company continuing from a corporation governed under the Canada Business Corporations Act (“CBCA”) to a corporation continued under the Business Corporations Act (Alberta) (“ABCA”) (the “Continuance”).

YOUR VOTE IS IMPORTANT – PLEASE VOTE “FOR” TODAY
The Proxy Voting Deadline is 11:00 a.m. (EST) on Friday, March 27, 2026

Vote Today

Shareholders are reminded to submit their proxies ahead of the proxy voting deadline. The proxy voting deadline is 11:00 a.m. (Eastern time) on Friday, March 27, 2026. Shareholders are encouraged to vote well in advance of the deadline to ensure their vote is submitted in a timely manner.

Details of the Meeting

A special meeting of Shareholders to seek approval of the Arrangement and the Continuance (the “Meeting”), has been reconvened to March 31, 2026 at 11:00 a.m. (EST) (the “Reconvened Meeting”). The Reconvened Meeting will be held virtually via live audio webcast at https://meetings.lumiconnect.com/400-581-122-608. The Meeting was postponed to address comments raised by the United States Securities and Exchange Commission (“SEC”) on the Company’s transaction statement on Schedule 13E-3, as amended. The record date for the Reconvened Meeting was the close of business on February 24, 2026.

Aptose has prepared and filed with the SEC a definitive proxy statement for the Reconvened Meeting (the “Proxy Statement”). A copy of the Proxy Statement has been mailed to all Shareholders of the Company. The Proxy Statement, form of proxy, letter of transmittal, as well as Schedule 13E-3, as amended, will also be available for download under Aptose’s profile on SEDAR+ at www.sedarplus.ca and EDGAR at www.sec.gov.

On December 12, 2025, Aptose obtained an interim order from the Court of King’s Bench of Alberta (the “Court”) authorizing the holding of the Meeting and matters relating to the conduct of the Meeting.

All Shareholders who wish to attend the Reconvened Meeting must follow the procedures set out in the Proxy Statement. Shareholders who are unable to attend the Reconvened Meeting are strongly encouraged to complete, date, sign and return the form of proxy (in the case of registered Shareholders) or voting instruction form (in the case of non-registered Shareholders) provided with the meeting materials so that as many Shareholders as possible are represented and vote at the Reconvened Meeting.

Aptose Board Recommendation

Aptose’s Special Transaction Committee and Board of Directors unanimously recommend that the Shareholders vote FOR the special resolutions approving the Continuance and the Arrangement Resolution at the Reconvened Meeting.

The completion of the Transaction is subject to satisfaction of customary closing conditions, including Court approval and approval of the TSX.

Shareholder Questions & Voting Assistance

Aptose has retained Morrow Sodali (Canada) Ltd. (“Sodali & Co”) to assist the Company in connection with shareholder communications and proxy solicitation. Shareholders who have questions or require voting assistance may contact Sodali & Co at:

Call Toll-Free (North America): 1-833-711-4830
Call Collect Outside North America: 1-289-695-3075
Email: assistance@investor.sodali.com  

About Aptose

Aptose Biosciences Inc. 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 frontline triplet therapy in newly diagnosed AML. For more information, please visit www.aptose.com.

Forward Looking Statements

This news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking information”) within the meaning of applicable securities laws. This information includes, but is not limited to, statements concerning our objectives, our strategies to achieve those objectives, as well as statements made with respect to management’s beliefs, plans, estimates, projections and intentions, and similar statements concerning anticipated future events, results, circumstances, performance or expectations that are not historical facts. In some cases, forward-looking information can be identified by the use of forward-looking terminology such as “expects”, “estimates”, “outlook”, “forecasts”, “projection”, “prospects”, “intends”, “anticipates”, “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might”, “will”, “will be taken”, “occur” or “be achieved”. In addition, any statements that refer to expectations, intentions, projections or other characterizations of future events or circumstances contain forward-looking information. Statements containing forward-looking information are not historical facts but instead represent management’s expectations, estimates and projections regarding future events or circumstances. Forward-looking information in this news release include, among other things, statements relating to the Arrangement and the Continuance, the Meeting, closing conditions and various other steps to be completed in connection with the Arrangement.

Risks and uncertainties related to the transactions contemplated by the Transaction include, but are not limited to: the possibility that the Transaction will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise, required regulatory, shareholder and Court approvals and other conditions to the completion of the Transaction or for other reasons; the risk that competing offers or acquisition proposals will be made; the negative impact that the failure to complete the Transaction for any reason could have on the price of the common shares of Aptose or on the business of Aptose; Hanmi Purchasers’ failure to pay the cash consideration at completion of the Transaction; the business of Aptose may experience significant disruptions, including loss of employees due to transaction related uncertainty, industry conditions or other factors; risks relating to employee retention; the risk of regulatory changes that may materially impact the business or the operations of Aptose; risks related to the diversion of management’s attention from Aptose’s ongoing business operations while the Transaction is pending; and other risks and uncertainties affecting Aptose, including those described in filings and reports Aptose may make from time to time with the Canadian securities authorities. Although we have attempted to identify important risk factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other risk factors not presently known to us or that we presently believe are not material that could also cause actual results or future events to differ materially from those expressed in such forward-looking information. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. No forward-looking statement is a guarantee of future results. Accordingly, you should not place undue reliance on forward-looking information, which speaks only as of the date made. The forward-looking information contained in this news release represents the Company’s expectations as of the date of this news release (or as the date they are otherwise stated to be made) and are subject to change after such date. However, the Company disclaims any intention or obligation or undertaking to update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required under applicable securities laws in Canada. All of the forward-looking information contained in this news release is expressly qualified by the foregoing cautionary statements.

This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell, or an offer to sell or a solicitation of an offer to buy, common shares of Aptose.

For further information, please contact:

Aptose Biosciences Inc.                                         
Susan Pietropaolo                                                                                   
Corporate Communications & Investor Relations                        
201-923-2049                                                               
spietropaolo@aptose.com

In making its recommendation that Shareholders vote FOR the Arrangement Resolution, ISS noted:

“The offer price represents a premium to the unaffected price. In addition, the initial market reaction was positive, no other bidders have presented a superior proposal, and there has been no public opposition from non-Hanmi shareholders. The cash form of consideration provides liquidity and certainty of value to Aptose shareholders.”

ISS also recommended approval of a continuance that will result in the Company continuing from a corporation governed under the Canada Business Corporations Act (“CBCA”) to a corporation continued under the Business Corporations Act (Alberta) (“ABCA”) (the “Continuance”). According to ISS, shareholder rights under the two statutes are largely similar and there would be no adverse impact on such rights on account of the Continuance.

Transaction Details
As previously disclosed in the Company’s news release dated November 19, 2025 (here), upon the completion of the Arrangement, 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) and Aptose will have continued from a corporation incorporated under the CBCA to a corporation continued under the ABCA.

Details of the Meeting

A special meeting of Shareholders to seek approval of the Arrangement and the Continuance (the “Meeting”), has been reconvened to March 31, 2026 at 11:00 a.m. (EST) (the “Reconvened Meeting”). The Reconvened Meeting will be held virtually via live audio webcast at https://meetings.lumiconnect.com/400-581-122-608. The Original Meeting was postponed to address comments raised by the United States Securities and Exchange Commission (“SEC”) on the Company’s transaction statement on Schedule 13E-3, as amended. The record date for the Meeting was the close of business on February 24, 2026.

Aptose has prepared and filed with the SEC a definitive proxy statement for the Reconvened Meeting (the “Proxy Statement”). A copy of the Proxy Statement has been mailed to all Shareholders of the Company. The Proxy Statement, form of proxy, letter of transmittal, as well as Schedule 13E-3, as amended, will also be available for download under Aptose’s profile on SEDAR+ at www.sedarplus.ca and EDGAR at www.sec.gov.

On December 12, 2025, Aptose obtained an interim order from the Court of King’s Bench of Alberta (the “Court”) authorizing the holding of the Meeting and matters relating to the conduct of the Meeting.

Shareholders Encouraged to Vote Ahead of the Proxy Deadline

Aptose’s board of directors unanimously recommends that the shareholders vote FOR the special resolutions approving the Continuance and the Arrangement Resolution at the Reconvened Meeting.

The proxy voting deadline is 11:00 a.m. (Eastern time) on Friday, March 27, 2026. Shareholders are encouraged to vote well in advance of the deadline to ensure their vote is submitted in a timely manner.

All shareholders who wish to attend the Reconvened Meeting must follow the procedures set out in the Proxy Statement. Shareholders who are unable to attend the Reconvened Meeting are strongly encouraged to complete, date, sign and return the form of proxy (in the case of registered shareholders) or voting instruction form (in the case of non-registered shareholders) provided with the meeting materials so that as many shareholders as possible are represented and vote at the Reconvened Meeting.

The completion of the Transaction is subject to satisfaction of customary closing conditions, including Court approval and approval of the TSX.

Shareholder Questions & Voting Assistance

Aptose has retained Morrow Sodali (Canada) Ltd. ("Sodali & Co") to assist the Company in connection with shareholder communications and proxy solicitation. Shareholders who have questions or require voting assistance may contact Sodali & Co at:

Call Toll-Free (North America): 1-833-711-4830
Call Collect Outside North America: 1-289-695-3075
Email: assistance@investor.sodali.com  

About Aptose

Aptose Biosciences Inc. 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 frontline triplet therapy in newly diagnosed AML. For more information, please visit www.aptose.com.

Forward Looking Statements

This news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking information”) within the meaning of applicable securities laws. This information includes, but is not limited to, statements concerning our objectives, our strategies to achieve those objectives, as well as statements made with respect to management’s beliefs, plans, estimates, projections and intentions, and similar statements concerning anticipated future events, results, circumstances, performance or expectations that are not historical facts. In some cases, forward-looking information can be identified by the use of forward-looking terminology such as “expects”, “estimates”, “outlook”, “forecasts”, “projection”, “prospects”, “intends”, “anticipates”, “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might”, “will”, “will be taken”, “occur” or “be achieved”. In addition, any statements that refer to expectations, intentions, projections or other characterizations of future events or circumstances contain forward-looking information. Statements containing forward-looking information are not historical facts but instead represent management’s expectations, estimates and projections regarding future events or circumstances. Forward-looking information in this news release include, among other things, statements relating to the Arrangement and the Continuance, the Meeting, closing conditions and various other steps to be completed in connection with the Arrangement.

Risks and uncertainties related to the transactions contemplated by the Transaction include, but are not limited to: the possibility that the Transaction will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise, required regulatory, shareholder and Court approvals and other conditions to the completion of the Transaction or for other reasons; the risk that competing offers or acquisition proposals will be made; the negative impact that the failure to complete the Transaction for any reason could have on the price of the common shares of Aptose or on the business of Aptose; Hanmi Purchasers’ failure to pay the cash consideration at completion of the Transaction; the business of Aptose may experience significant disruptions, including loss of employees due to transaction related uncertainty, industry conditions or other factors; risks relating to employee retention; the risk of regulatory changes that may materially impact the business or the operations of Aptose; risks related to the diversion of management’s attention from Aptose’s ongoing business operations while the Transaction is pending; and other risks and uncertainties affecting Aptose, including those described in filings and reports Aptose may make from time to time with the Canadian securities authorities. Although we have attempted to identify important risk factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other risk factors not presently known to us or that we presently believe are not material that could also cause actual results or future events to differ materially from those expressed in such forward-looking information. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. No forward-looking statement is a guarantee of future results. Accordingly, you should not place undue reliance on forward-looking information, which speaks only as of the date made. The forward-looking information contained in this news release represents the Company’s expectations as of the date of this news release (or as the date they are otherwise stated to be made) and are subject to change after such date. However, the Company disclaims any intention or obligation or undertaking to update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required under applicable securities laws in Canada. All of the forward-looking information contained in this news release is expressly qualified by the foregoing cautionary statements.

This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell, or an offer to sell or a solicitation of an offer to buy, common shares of Aptose.

For further information, please contact:

Aptose Biosciences Inc.
Susan Pietropaolo
Corporate Communications & Investor Relations
201-923-2049
spietropaolo@aptose.com

SAN DIEGO and TORONTO, Feb. 24, 2026 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS; OTC: APTOF) announced today that it has entered into an amended and restated arrangement agreement dated February 23, 2026 (the “Amended and Restated Arrangement Agreement”) amending and restating the arrangement agreement dated November 18, 2025 (the “Original Arrangement Agreement”), pursuant to which Aptose will continue from the Canada Business Corporations Act to the Business Corporations Act (Alberta) (“ABCA”) (the “Continuance”) and subsequently be acquired by HS North America Ltd. (the “Purchaser”), a wholly owned subsidiary of Hanmi Pharmaceutical Co. Ltd. (“Hanmi” and together with the Purchaser, the “Hanmi Purchasers”), by way of a statutory plan of arrangement under the ABCA (the “Arrangement” and, together with the Continuance, the “Transaction”).

The Amended and Restated Arrangement Agreement amends and restates the Original Arrangement Agreement to, among other things, schedule a new date for the special meeting of shareholders to seek approval of the Transaction (the “Meeting”), originally scheduled to be held on January 16, 2026 (the “Original Meeting”) which has been reconvened to March 31, 2026 at 11:00 a.m. (EST) (the “Reconvened Meeting”). The Original Meeting was postponed to address comments raised by the United States Securities and Exchange Commission (“SEC”) on the Company’s transaction statement on Schedule 13E-3, as amended.

Aptose has prepared and filed with the SEC a definitive proxy statement for the Reconvened Meeting (the “Proxy Statement”). A copy of the Proxy Statement will be mailed to all shareholders of the Company as soon as practicable. The Proxy Statement, form of proxy, letter of transmittal, as well as Schedule 13E-3, as amended, will also be available for download under Aptose’s profile on SEDAR+ at www.sedarplus.ca and EDGAR at www.sec.gov.

On December 12, 2025, Aptose obtained an interim order from the Court of King’s Bench of Alberta (the “Court”) authorizing the holding of the Meeting and matters relating to the conduct of the Meeting.

Aptose also announced a revised record date for the Meeting, now set for the close of business on February 24, 2026.

The Reconvened Meeting will be held virtually via live audio webcast at https://meetings.lumiconnect.com/400-581-122-608. All shareholders who wish to attend the Reconvened Meeting must follow the procedures set out in the Proxy Statement. Shareholders who are unable to attend the Reconvened Meeting are strongly encouraged to complete, date, sign and return the form of proxy (in the case of registered shareholders) or voting instruction form (in the case of non-registered shareholders) provided with the meeting materials so that as many shareholders as possible are represented and vote at the Reconvened Meeting.

Aptose’s board of directors unanimously recommends that the shareholders vote FOR the special resolutions approving the Continuance and the Arrangement at the Reconvened Meeting.

Aptose also announced today that it has entered into a US$11.1 million second amended and restated 2025 facility agreement with Hanmi (the “Second A&R 2025 Facility Agreement”).

The Second A&R 2025 Facility Agreement is uncommitted and administered through multiple advances until May 31, 2026, and will be used to fund Aptose’s business and clinical operations expenses reasonably related to the advancement of Tuspetinib (“TUS”). Aptose has not yet received funds from the Second A&R 2025 Facility Agreement but expects the first advance soon. This Second A&R 2025 Facility Agreement has been amended and restated from the prior December 2025 amended and restated facility agreement between Hanmi and Aptose, which was amended and restated from the prior September 2025 facility agreement between Hanmi and Aptose. No single advance shall be for an amount in excess of US$2,000,000, and any unpaid principal amount with respect to each advance shall accrue interest at six percent (6%) per annum. The Second A&R 2025 Facility Agreement contains customary affirmative and negative covenants and securities that are subject to a number of limitations and exceptions.

Each of the September 2025 facility agreement and December 2025 amended and restated facility 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. In its consideration and approval of the September 2025 facility agreement and December 2025 amended and restated facility agreement, the board of directors of the Company, acting in good faith and having taken into account the liquidity, financial position and cash needs of the Company, the alternatives available to the Company, relevant benefits, risks and other factors, including the relative impacts on applicable stakeholders, and such matters they considered relevant or appropriate, unanimously determined that entering into the September 2025 facility agreement and December 2025 amended and restated facility agreement will result in an improvement of the Company’s financial position, and that the terms of the September 2025 facility agreement and December 2025 amended and restated facility agreement are reasonable in the circumstances of Aptose.

About Aptose

Aptose Biosciences Inc. 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 frontline triplet therapy in newly diagnosed AML. For more information, please visit www.aptose.com.

Forward Looking Statements

This news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking information”) within the meaning of applicable securities laws. This information includes, but is not limited to, statements concerning our objectives, our strategies to achieve those objectives, as well as statements made with respect to management’s beliefs, plans, estimates, projections and intentions, and similar statements concerning anticipated future events, results, circumstances, performance or expectations that are not historical facts. In some cases, forward-looking information can be identified by the use of forward-looking terminology such as “expects”, “estimates”, “outlook”, “forecasts”, “projection”, “prospects”, “intends”, “anticipates”, “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might”, “will”, “will be taken”, “occur” or “be achieved”. In addition, any statements that refer to expectations, intentions, projections or other characterizations of future events or circumstances contain forward-looking information. Statements containing forward-looking information are not historical facts but instead represent management’s expectations, estimates and projections regarding future events or circumstances. Forward-looking information in this news release include, among other things, statements relating to Aptose’s business in general; statements related to expectations regarding the delisting of Aptose's securities from the TSX; statements relating to the Reconvened Meeting and the timing thereof, the expected impact on the record date, the mailing of the proxy statement, form of proxy, letter of transmittal along with any additional required disclosure in connection with the Reconvened Meeting and the timing thereof.

Risks and uncertainties related to the transactions contemplated by the Transaction include, but are not limited to: the possibility that the Transaction will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise, required regulatory, shareholder and Court approvals and other conditions to the completion of the Transaction or for other reasons; the risk that competing offers or acquisition proposals will be made; the negative impact that the failure to complete the Transaction for any reason could have on the price of the common shares of Aptose or on the business of Aptose; Hanmi Purchasers’ failure to pay the cash consideration at completion of the Transaction; the business of Aptose may experience significant disruptions, including loss of employees due to transaction related uncertainty, industry conditions or other factors; risks relating to employee retention; the risk of regulatory changes that may materially impact the business or the operations of Aptose; risks related to the diversion of management’s attention from Aptose’s ongoing business operations while the Transaction is pending; and other risks and uncertainties affecting Aptose, including those described in filings and reports Aptose may make from time to time with the Canadian securities authorities. Although we have attempted to identify important risk factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other risk factors not presently known to us or that we presently believe are not material that could also cause actual results or future events to differ materially from those expressed in such forward-looking information. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. No forward-looking statement is a guarantee of future results. Accordingly, you should not place undue reliance on forward-looking information, which speaks only as of the date made. The forward-looking information contained in this news release represents the Company’s expectations as of the date of this news release (or as the date they are otherwise stated to be made) and are subject to change after such date. However, the Company disclaims any intention or obligation or undertaking to update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required under applicable securities laws in Canada. All of the forward-looking information contained in this news release is expressly qualified by the foregoing cautionary statements.

This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell, or an offer to sell or a solicitation of an offer to buy, common shares of Aptose.

For further information, please contact:

Aptose Biosciences Inc.
Susan Pietropaolo
Corporate Communications & Investor Relations
201-923-2049 
spietropaolo@aptose.com

Aptose has determined to reschedule the Meeting after it receives final clearance of the proxy statement from the United States Securities and Exchange Commission (“SEC”). Following the clearance from the SEC, Aptose will announce the new date, time and virtual details for the Meeting. Aptose intends to mail to all shareholders, and to make available under its profile on SEDAR+ at www.sedarplus.ca and EDGAR at www.sec.gov, the proxy statement, form of proxy, letter of transmittal along with any additional required disclosure in connection with the Meeting.

On December 12, 2025, Aptose obtained an interim order from the Court of King’s Bench of Alberta (the “Court”) authorizing the holding of the Meeting and matters relating to the conduct of the Meeting.

The Company’s board of directors unanimously recommends that the holders of Aptose common shares vote FOR the special resolutions approving the Continuance and the Arrangement at the Meeting.

About Aptose

Aptose Biosciences Inc. 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 news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking information”) within the meaning of applicable securities laws. This information includes, but is not limited to, statements concerning our objectives, our strategies to achieve those objectives, as well as statements made with respect to management’s beliefs, plans, estimates, projections and intentions, and similar statements concerning anticipated future events, results, circumstances, performance or expectations that are not historical facts. In some cases, forward-looking information can be identified by the use of forward-looking terminology such as “expects”, “estimates”, “outlook”, “forecasts”, “projection”, “prospects”, “intends”, “anticipates”, “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might”, “will”, “will be taken”, “occur” or “be achieved”. In addition, any statements that refer to expectations, intentions, projections or other characterizations of future events or circumstances contain forward-looking information. Statements containing forward-looking information are not historical facts but instead represent management’s expectations, estimates and projections regarding future events or circumstances. Forward-looking information in this news release include, among other things, statements relating to Aptose’s business in general; statements relating to the postponed Meeting and the timing thereof, the expected impact on the record date, the clearance from the SEC and the timing thereof the mailing of the proxy statement, form of proxy, letter of transmittal along with any additional required disclosure in connection with the Meeting and the timing thereof.

Risks and uncertainties related to the transactions contemplated by the Transaction include, but are not limited to: the possibility that the Transaction will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise, required regulatory, shareholder and Court approvals and other conditions to the completion of the Transaction or for other reasons; the risk that competing offers or acquisition proposals will be made; the negative impact that the failure to complete the Transaction for any reason could have on the price of the common shares of Aptose or on the business of Aptose; Hanmi Purchaser’s failure to pay the cash consideration at completion of the Transaction; the business of Aptose may experience significant disruptions, including loss of employees due to transaction related uncertainty, industry conditions or other factors; risks relating to employee retention; the risk of regulatory changes that may materially impact the business or the operations of Aptose; risks related to the diversion of management’s attention from Aptose’s ongoing business operations while the Transaction is pending; and other risks and uncertainties affecting Aptose, including those described in filings and reports Aptose may make from time to time with the Canadian securities authorities. Although we have attempted to identify important risk factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other risk factors not presently known to us or that we presently believe are not material that could also cause actual results or future events to differ materially from those expressed in such forward-looking information. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. No forward-looking statement is a guarantee of future results. Accordingly, you should not place undue reliance on forward-looking information, which speaks only as of the date made. The forward-looking information contained in this news release represents the Company’s expectations as of the date of this news release (or as the date they are otherwise stated to be made) and are subject to change after such date. However, the Company disclaims any intention or obligation or undertaking to update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required under applicable securities laws in Canada. All of the forward-looking information contained in this news release is expressly qualified by the foregoing cautionary statements.

This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell, or an offer to sell or a solicitation of an offer to buy, common shares of Aptose.

For further information, please contact:

Aptose Biosciences Inc.
Susan Pietropaolo
Corporate Communications & Investor Relations
201-923-2049
spietropaolo@aptose.com

SAN DIEGO and TORONTO, Dec. 06, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (NASDAQ: APTO, TSX: APS), a clinical-stage precision oncology company developing highly differentiated targeted agents to treat hematologic malignancies, today featured clinical data for its lead compound tuspetinib (TUS) combined with standard dosing of venetoclax (VEN) and azacitidine (AZA) in a poster presentation at the 67^th American Society of Hematology (ASH) Annual Meeting in Orlando, FL. Updated data from patients in the TUSCANY trial across all three cohorts, 40 mg, 80 mg or 120 mg TUS dose in TUS+VEN+AZA, reveal promising clinical safety and antileukemic activity and support the use of TUS in combination with standard of care treatment across a broad range of AML populations, including those with adverse mutations regardless of FLT3 mutation status.  

Poster title: “TUSCANY study demonstrates safety and efficacy of tuspetinib plus standard of care venetoclax and azacitidine in patients with newly diagnosed AML ineligible for induction chemotherapy”

Key Findings and Messages:

• In newly diagnosed AML patients, TUS+VEN+AZA shows promising safety, tolerability and resilient efficacy, including MRD-negative remissions across a broad mutational spectrum
• High-quality clinical responses (CR/CRh):
  • 90% across 40, 80 and 120 mg dose levels
  • 100% at the higher 80 mg and 120 mg dose levels
  • Observed in FLT3-WT, FLT3-ITD, and NPM1c genetic subgroups
  • Observed in biallelic TP53/complex karyotype and RAS adverse genetic subgroups
  • Observed in AML with MDS-related mutations
• MRD negativity: 78% by central flow cytometry in responding subjects
• TUS targets VEN resistance mechanisms; inhibits kinase-driven abnormal signaling
• Two subjects transitioned to stem cell transplantation and both returned for TUS maintenance
• TUS+VEN+AZA triplet therapy was well tolerated with no dose-limiting toxicities (DLTs) across all evaluable TUS dose levels
  • No DLTs including no prolonged myelosuppression for subjects in remission in Cycle 1
  • No drug-related deaths, differentiation syndrome, QTc prolongation, or CPK elevation reported
  • 8/10 evaluable subjects experienced red cell and platelet transfusion independence for > 8 weeks after their best response
  • Febrile neutropenia was reported in 2 subjects (16.7%), with 1 subject related to TUS
• At the recently enrolled 160 mg dose level, preliminary findings show patients achieving early blast clearance with MRD-negativity and formal responses in the first few weeks of treatment (not included in poster data cut).
  
  

“Tuspetinib, as part of a triple drug therapy, continues to perform well, achieving 100% clinical response in the two higher doses we have evaluated to date,” said Rafael Bejar, MD, PhD, Chief Medical Officer at Aptose. “We recently commenced treating patients at the highest dose level of 160 mg TUS and have already achieved early responses. With no dose-limiting toxicities and activity across diverse mutations, TUS+VEN+AZA targets AML’s greatest unmet needs and largest populations.”

The ASH poster presentation is available here.

About Tuspetinib

Aptose’s lead compound 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. Data from the first three dose cohorts demonstrate safety, CRs and minimal residual disease (MRD) negativity across patients with diverse mutations. The early data showed that 9 out of 10 patients responded to the TUS triplet therapy, with 100% complete remission (CR/CRh) achieved in the 80mg and 120mg cohorts. Notably, patients with difficult-to-treat mutations in TP53, RAS and FLT3 genes also achieved a 100% CR/CRh rate.

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 without overlapping toxicities. The Company’s lead clinical-stage compound tuspetinib (TUS), is an oral kinase inhibitor that has demonstrated activity as 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 therapeutic potential of tuspetinib, its clinical development and safety profile including its tolerability and resilient efficacy, 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. 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 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 Pietropaolo                        
Corporate Communications & Investor Relations                        
201-923-2049                        
spietropaolo@aptose.com

SAN DIEGO and TORONTO, Nov. 19, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS; OTC: APTOF) and Hanmi Pharmaceutical Co. Ltd. (“Hanmi”) today announced that Aptose, Hanmi and HS North America Ltd., a wholly owned subsidiary of Hanmi (“Hanmi Purchaser” and together with Hanmi, the “Hanmi Purchasers”), have entered into a definitive arrangement agreement (the “Arrangement Agreement”) pursuant to which Hanmi Purchaser will acquire all of the issued and outstanding common shares of Aptose (“Common Shares”) that are not currently owned or controlled by the Hanmi Purchasers or their respective affiliates.

Hanmi has participated in multiple financings of Aptose and owns 19.93% of all outstanding Common Shares. During the past 18 months, Hanmi has singularly supported Aptose and the continued development of tuspetinib (TUS) through debt facilities to Aptose totaling more than US$30 million. Under the terms of the Arrangement Agreement, upon the completion of the transactions contemplated under the Arrangement Agreement, 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). 

“We are very pleased to have reached an agreement on a transaction with Hanmi,” stated William G. Rice, Ph.D., Chairman, President, and Chief Executive Officer of Aptose. “This transaction not only offers a premium value for our minority shareholders but also enables Aptose to continue the development of TUS combined with standard treatment venetoclax plus azacitidine (VEN+AZA) for acute myeloid leukemia (AML) in the TUSCANY Phase 1/2 clinical study. The TUS+VEN+AZA triplet therapy has shown promising response rates and safety in a diverse population of patients newly diagnosed with AML. We are extremely grateful for Hanmi’s ongoing support as we work toward our long-term goal of improving patient outcomes in AML.”

“We are very pleased to have reached this agreement with Aptose,” said Jae-Hyun Park of Hanmi. “With a growing body of positive data, it is important to support the uninterrupted and expanded development of tuspetinib in the TUSCANY clinical study. This step also marks Hanmi’s first beachhead and direct entry into North America, establishing a strategic foothold for future partnerships and clinical expansion in the region.”

Transaction Details

Under the terms of Arrangement Agreement, Aptose will continue from a corporation incorporated under the Canada Business Corporations Act to a corporation continued under the Business Corporations Act (Alberta) (the “Continuance”) and, following the completion of the Continuance, Hanmi Purchaser will acquire all of the issued and outstanding Common Shares that are not currently owned or controlled by the Hanmi Purchasers or their respective affiliates by way of a plan of arrangement under the Business Corporations Act (Alberta) (the “Arrangement” and, together with the Continuance, the “Transaction”).

Upon the completion of the Transaction, subject to applicable tax withholdings:

• each Common Share (other than any Common Share owned or controlled by the Hanmi Purchasers or their respective affiliates or for which dissent rights have been validly exercised) will be transferred to Hanmi Purchaser in exchange for an amount in cash equal to C$2.41 per Common Share;
• each Aptose option will cease to represent an option or other right to acquire any Common Share and will be deemed surrendered and exchanged for an amount in cash equal to C$2.41 per Common Share, multiplied by the number of Common Shares subject to the Aptose option, less the aggregate exercise price in respect of such Aptose option;
• each Aptose restricted share unit will cease to represent a share unit of Aptose and will be deemed surrendered and exchanged for an amount in cash equal to C$2.41 per Common Share, multiplied by the number of Common Shares subject to the Aptose restricted share unit;
• each Aptose warrant held by Armistice Capital Master Fund Ltd. (the “Armistice Warrants”) will cease to represent a warrant exercisable for Common Shares and will be deemed surrendered and exchanged for an amount in cash equal to an amount calculated using the “Black Scholes” valuation model in accordance with the terms of the applicable Armistice Warrant; and
• each Aptose warrant (other than the Armistice Warrants) will cease to represent a warrant exercisable for Common Shares and will be deemed surrendered and exchanged for an amount in cash equal to C$2.41 per Common Share, multiplied by the number of Common Shares subject to the Aptose warrant, less the aggregate exercise price in respect of such Aptose warrant.
  

The Arrangement Agreement contains customary non-solicitation provisions prohibiting Aptose from soliciting competing acquisition proposals, as well as “right to match” provisions in favour of Hanmi Purchaser. The Arrangement Agreement provides for a C$300,000 expense fee payable to Hanmi Purchaser if the Arrangement Agreement is terminated in certain circumstances, including in the context of a change in recommendation by the board of directors of Aptose (the “Board”) or by the special committee consisting of independent members of the Board formed in connection with the Arrangement (the “Special Committee”).

The completion of the Transaction is subject to satisfaction of customary closing conditions, including court approval and approval of Aptose shareholders as further set out below. After completion of the Transaction, Aptose expects to no longer be subject to the reporting requirements of applicable Canadian securities legislation and the Common Shares will be delisted from all stock exchanges where Common Shares are currently listed, including the TSX.

Completion of the Transaction will be subject to the approval of (i) at least two-thirds (66 2/3%) of the votes cast by Aptose shareholders present in person or represented by proxy at a special meeting of Aptose shareholders to be held no later than January 16, 2026 to approve the Transaction (the “Special Meeting”), voting as a single class, and (ii) the majority of the holders of Common Shares present in person or represented by proxy at the Special Meeting, excluding the votes of the Hanmi Purchasers and their respective affiliates, and any other shareholders whose votes are required to be excluded for the purposes of “minority approval” under Multilateral Instrument 61-101 – Protection of Minority Security Holders in Special Transactions (“MI 61-101”) in the context of a “business combination” (the “Minority Shareholders”). Further details regarding the applicable voting requirements will be contained in a management information circular to be filed and mailed to Aptose shareholders in connection with the Special Meeting to approve the Transaction.

Concurrent with the execution of the Arrangement Agreement, Hanmi Purchaser entered into voting support agreements with each of the directors and officers of Aptose pursuant to which, subject to the terms of the voting support agreements, each Aptose director or officer has agreed to, among other things, vote or cause to be voted all of the Common Shares owned, controlled or directed, directly or indirectly, by them in favour of the Transaction at the Special Meeting.

Further details of the Transaction are set out in the Arrangement Agreement, which will be made available on Aptose’s SEDAR+ profile at www.sedarplus.ca.

Opinion and Formal Valuation

Locust Walk Securities, LLC (“Locust Walk”) was retained by the Special Committee to provide financial advice and prepare a formal valuation of the Common Shares, as required under MI 61-101. Locust Walk delivered a valuation that, as of November 18, 2025, and based on Locust Walk’s analysis and subject to the assumptions, limitations and qualifications to be set forth in the formal valuation that will be included in the management information circular that will be sent to Aptose shareholders in connection with the Special Meeting (the “Formal Valuation”), using multiple analyses, including DCF modeling, the fair market value of the Common Shares is in the range of C$1.00 to C$5.23 per Common Share. Locust Walk has also delivered an oral opinion (the “Fairness Opinion”) to the Special Committee that, as of November 18, 2025, and subject to the assumptions, limitations and qualifications to be set forth in Locust Walk’s written fairness opinion that will be included in the management information circular, the consideration to be received by the holders of Common Shares (other than the Hanmi Purchasers and their respective affiliates) pursuant to the Arrangement Agreement is fair, from a financial point of view, to such holders of Common Shares. The management information circular will also include factors considered by the Special Committee and the Board and other relevant information.

Unanimous Approval of Aptose Special Committee and Board of Directors

The Special Committee, after consultation with and receiving advice from its financial adviser and outside legal counsel, has unanimously recommended that the Board approve the Arrangement and that Aptose shareholders vote in favour of the Arrangement.

The Board, acting on the unanimous recommendation in favour of the Arrangement by the Special Committee and after receiving advice from its financial adviser and outside legal counsel in evaluating the Arrangement, has unanimously determined that the Arrangement is fair to Aptose shareholders (other than the Hanmi Purchasers and their respective affiliates) and that the Arrangement is in the best interests of Aptose, and resolved to unanimously recommend that Aptose shareholders vote in favour of the Arrangement.

Advisors

Locust Walk is acting as financial advisor and independent valuator to the Special Committee and the Company. McCarthy Tétrault LLP is acting as independent legal advisor to the Special Committee and the Company. Stikeman Elliott LLP is acting as independent legal advisor to Hanmi Purchaser.

About Tuspetinib

Aptose’s lead compound 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 has reported data from the first three dose cohorts that have demonstrated safety, CRs and minimal residual disease (MRD) negativity across patients with diverse mutations. The early data showed that 9 out of 10 patients responded to the TUS triplet therapy, with 100% complete remission (CR/CRh) achieved in the 80mg and 120mg cohorts. Notably, patients with difficult-to-treat mutations in TP53, RAS and FLT3 genes also achieved a 100% CR/CRh rate (press release here).

About Hanmi

Hanmi Pharmaceutical Co., Ltd., founded in 1973 in Seoul, South Korea, is a leading global biopharmaceutical company focused on developing innovative drugs in the fields of oncology, diabetes, obesity, and other metabolic diseases. The company operates GMP-compliant facilities in Hwaseong, Pyeongtaek, and Siheung, Gyeonggi-do, producing high-quality APIs and finished products exported worldwide. Renowned for pioneering R&D partnerships with Janssen, Roche, MSD, and Gilead, Hanmi drives patient-centric, first-in-class therapies as a top player in Korea’s pharmaceutical industry. For more information, please visit www.hanmipharm.com.

About Aptose

Aptose Biosciences Inc. 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 news release contains “forward-looking information” and “forward-looking statements” (collectively, “forward-looking information”) within the meaning of applicable securities laws. This information includes, but is not limited to, statements concerning our objectives, our strategies to achieve those objectives, as well as statements made with respect to management’s beliefs, plans, estimates, projections and intentions, and similar statements concerning anticipated future events, results, circumstances, performance or expectations that are not historical facts. In some cases, forward-looking information can be identified by the use of forward-looking terminology such as “expects”, “estimates”, “outlook”, “forecasts”, “projection”, “prospects”, “intends”, “anticipates”, “believes”, or variations of such words and phrases or statements that certain actions, events or results “may”, “could”, “would”, “might”, “will”, “will be taken”, “occur” or “be achieved”. In addition, any statements that refer to expectations, intentions, projections or other characterizations of future events or circumstances contain forward-looking information. Statements containing forward-looking information are not historical facts but instead represent management’s expectations, estimates and projections regarding future events or circumstances. Forward-looking information in this news release include, among other things, statements relating to Aptose’s business in general; statements relating to the Transaction, the ability to complete the transactions contemplated by the Arrangement Agreement and the timing thereof, including the parties’ ability to satisfy the conditions to the completion of the Transaction, the receipt of the required Aptose shareholder approval and court approval and other customary closing conditions, the possibility of any termination of the Arrangement Agreement in accordance with its terms, and the expected benefits to the Company and its shareholders of the proposed Transaction.

Risks and uncertainties related to the transactions contemplated by the Arrangement Agreement include, but are not limited to: the possibility that the Transaction will not be completed on the terms and conditions, or on the timing, currently contemplated, and that it may not be completed at all, due to a failure to obtain or satisfy, in a timely manner or otherwise, required regulatory, shareholder and court approvals and other conditions to the completion of the Transaction or for other reasons; the risk that competing offers or acquisition proposals will be made; the negative impact that the failure to complete the Transaction for any reason could have on the price of the Common Shares or on the business of Aptose; Hanmi Purchaser’s failure to pay the cash consideration at completion of the Transaction; the business of Aptose may experience significant disruptions, including loss of employees due to transaction related uncertainty, industry conditions or other factors; risks relating to employee retention; the risk of regulatory changes that may materially impact the business or the operations of Aptose; risks related to the diversion of management’s attention from Aptose’s ongoing business operations while the Transaction is pending; and other risks and uncertainties affecting Aptose, including those described in filings and reports Aptose may make from time to time with the Canadian securities authorities. Although we have attempted to identify important risk factors that could cause actual results to differ materially from those contained in forward-looking information, there may be other risk factors not presently known to us or that we presently believe are not material that could also cause actual results or future events to differ materially from those expressed in such forward-looking information. There can be no assurance that such information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such information. No forward-looking statement is a guarantee of future results. Accordingly, you should not place undue reliance on forward-looking information, which speaks only as of the date made. The forward-looking information contained in this news release represents the Company’s expectations as of the date of this news release (or as the date they are otherwise stated to be made) and are subject to change after such date. However, the Company disclaims any intention or obligation or undertaking to update or revise any forward-looking information whether as a result of new information, future events or otherwise, except as required under applicable securities laws in Canada. All of the forward-looking information contained in this news release is expressly qualified by the foregoing cautionary statements.

This announcement is for informational purposes only and does not constitute an offer to purchase or a solicitation of an offer to sell, or an offer to sell or a solicitation of an offer to buy, Common Shares.

For further information, please contact:

Aptose Biosciences Inc.                                         
Susan Pietropaolo                                                                                   
Corporate Communications & Investor Relations                        
201-923-2049
spietropaolo@aptose.com

SAN DIEGO and TORONTO, Nov. 13, 2025 (GLOBE NEWSWIRE) -- 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 financial results for the third quarter ended September 30, 2025, and provided a corporate update.

“Tuspetinib in combination with VEN+AZA standard treatment (TUS+VEN+AZA) has been highly active and so well tolerated in newly diagnosed AML patients with 40 mg, 80 mg, and 120 mg TUS, we dose escalated to the 160 mg TUS dose level in the triplet,” said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer of Aptose. “Patients evaluated at the higher dose levels of 80 mg and 120 mg TUS have all (6/6; 100%) achieved CR/CRh responses, exceeding the 66% rate expected from VEN+AZA alone. We now are dosing at 160 mg TUS, and we look forward to providing further updates next month at ASH.”

Key Corporate Highlights    

• Tuspetinib Data Reported at European School of Haematology (ESH) 7th International Conference Data from the ongoing TUSCANY trial of tuspetinib in combination with venetoclax and azacitidine (TUS+VEN+AZA) were presented in a poster presentation, “TUSCANY Study of Safety and Efficacy of Tuspetinib plus Standard of Care Venetoclax and Azacitidine in Study Participants with Newly Diagnosed AML Ineligible for Induction Chemotherapy,” at the European School of Haematology (ESH) 7th International Conference on Acute Myeloid Leukemia “Molecular and Translational”: Advances in Biology and Treatment, held in October in Estoril, Portugal. Data from 10 patients in the TUSCANY trial across all three cohorts, 40 mg, 80 mg or 120 mg TUS dose in TUS+VEN+AZA, reveal promising clinical safety and antileukemic activity and support the use of TUS with standard of care treatment across a broad range of AML populations, including those carrying adverse mutations regardless of FLT3 mutation status.
  
  As reported, the addition of TUS to VEN+AZA achieved CR/CRh responses in 6/6 (100%) patients treated at the higher dose levels of 80 mg and 120 mg TUS, exceeding the 66% rate expected from VEN+AZA alone. Overall, TUS+VEN+AZA has delivered CR/CRh responses in 9/10 (90%) patients.  CR/CRh responses were achieved across diverse mutational subtypes including unmutated FLT3, FLT3-ITD, NPM1c, biallelic TP53 with complex karyotype, RAS, and myelodysplasia related mutations. MRD-negativity with TUS+VEN+AZA was observed in 7/9 (78%) of responding patients by central flow cytometry, and hematopoietic stem cell transplants (HSCT) have been completed in 2 patients to date.
  
  
• Aptose Clinical Data Accepted for Poster Presentation at ASH – Aptose was notified that its abstract, “TUSCANY Study demonstrates safety and efficacy of tuspetinib plus standard of care venetoclax and azacitidine in patients with newly diagnosed AML ineligible for induction chemotherapy,” has been selected for poster presentation at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition. The meeting is scheduled to take place December 6-9, 2025, in Orlando, Florida. The abstract accepted for presentation can be viewed online at the ASH conference website here, and will appear in the November supplemental issue of Blood. The actual presentation will include more recent updates and additional data not found in the abstract.

Completed and Planned Value-Creating Milestones

2025: 1H

• Reported safety and efficacy with 40mg TUS+VEN+AZA
• Reported safety and efficacy with 80mg TUS+VEN+AZA

2025: European Hematology Association (EHA)

• Reported maturing data from TUS+VEN+AZA triplet study

2025: 2H

• Reported safety and efficacy with 120 mg TUS+VEN+AZA
• CSRC review of data; decision to dose escalate to 160 mg TUS+VEN+AZA

2025:  European School of Haematology (ESH) 7th International Conference 

• Reported excellent safety across three TUS dose levels of TUS+VEN+AZA
• Reported CR/CRh responses in patients with biallelic TP53 mutations
• Reported evolving data from 120 mg TUS+VEN+AZA triplet

2025: American Society of Hematology (ASH)

• Report evolving response rate and durability data from four (4) dose levels of TUS+VEN+AZA triplet
• Report safety and tolerability of TUS with VEN+AZA in combination with unadjusted dosing of VEN+AZA

Net loss for the quarter ended September 30, 2025 decreased by $1.8 million to $5.1 million, as compared to $7.0 million for the comparable period in 2024. Net loss for the nine months ended September 30, 2025 decreased by $6.1 million to $17.7 million, as compared to $23.8 million for the comparable period in 2024. 

• Total cash, cash equivalents and restricted cash equivalents as of September 30, 2025 were $1.6 million. The Company does not have sufficient cash to fund operations and relies on advances made by Hanmi to fund operations. The Company is actively deploying financing and cost reduction efforts to extend cash runway.
  
• As of November 7, 2025, there were 2,552,429 common shares of the Company (“Common Shares”) issued and outstanding. In addition, there were 37,370 Common Shares issuable upon the exercise of outstanding stock options and there were 1,267,585 Common Shares issuable upon the exercise of the outstanding warrants.

RESEARCH AND DEVELOPMENT EXPENSES

Research and development expenses for the three and nine months ended September 30, 2025 and 2024 were as follows:

Research and development expenses decreased by $2.5 million to $2.2 million for the quarter ended September 30, 2025, as compared to $4.7 million for the comparable period in 2024. Changes to the components of our research and development expenses presented in the table above are primarily as a result of the following events:

• Program costs for tuspetinib were $1.4 million for the quarter ended September 30, 2025, compared with $4.1 million for the comparable period in 2024. The lower program costs for tuspetinib in the current period are attributable to reduced activity in our APTIVATE clinical trial, reduced manufacturing activity, and related expenses. 
• Program costs for luxeptinib increased by approximately $0.3 million during the three months ended September 30, 2025 compared to the comparable period in 2024 due to a refund provided by one of our clinical vendors during the three months ended September 30, 2024.
• The Company discontinued further development of APTO-253.
• Personnel-related expenses decreased by $0.3 million due to lower headcount for research and development personnel in the current quarter.
• Stock-based compensation increased by $0.1 million in the quarter ended September 30, 2025, compared to the comparable period in 2024, primarily due to forfeitures recognized during the three months ended September 30, 2024 in connection with employee terminations during the period.

Research and development expenses decreased by $7.7 million to $7.9 million for the nine months ended September 30, 2025, as compared to $15.6 million for the comparable period in 2024. Changes to the components of our research and development expenses presented in the table above are primarily as a result of the following events:

• Program costs for tuspetinib were $5.1 million for the nine months ending September 30, 2025, compared to $10.7 million for the comparable period in 2024. The increased costs associated with the TUSCANY study were offset by a decrease in tuspetinib development expenses during the current period. This reduction is due to the conclusion of activities in our APTIVATE clinical trial during the current period, compared to higher APTIVATE activities during the nine months ended September 30, 2024, as well as lower manufacturing and related development costs.
• Program costs for luxeptinib remained consistent during the nine months ended September 30, 2025 compared to the comparable period in 2024.
• The Company discontinued further development of APTO-253.
• Personnel-related expenses decreased by $2.0 million due to lower headcount for research and development personnel in the current quarter.
• Stock-based compensation decreased by approximately $0.1 million in the nine months ended September 30, 2025, compared to the comparable period in 2024, primarily due to stock options forfeited and/or vested in prior periods that are no longer being expensed resulting in lower expense in the current period.

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 contains forward-looking statements within the meaning of Canadian and U.S. securities laws, including, but not limited to, statements regarding the Company’s clinical development plans, the clinical potential, anti-cancer activity, therapeutic potential and applications and safety profile of tuspetinib, clinical trials, upcoming milestones and presentation of additional data, financing and cost reduction efforts, expectations regarding capital available to the Company to fund planned Company operations, the Company’s cash runway, and statements relating to the Company’s plans, objectives, expectations and intentions and other statements including words such as “continue”, “expect”, “intend”, “will”, “hope” “should”, “would”, “may”, “potential” 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 obtain the capital required for research and operations; 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 and economic conditions; unexpected manufacturing defects, the evolving regulatory and political landscape and the funding of government programs and other risks detailed from time-to-time in our ongoing current reports, quarterly filings, annual information forms, annual reports and
  
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

SAN DIEGO and TORONTO, Nov. 03, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS), 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 an abstract from its TUSCANY study of tuspetinib with standard of care venetoclax and azacitidine in patients with newly diagnosed AML has been selected for poster presentation at the 67^th American Society of Hematology (ASH) Annual Meeting and Exposition. The meeting is scheduled to take place December 6-9, 2025, in Orlando, Florida.

ASH Poster Presentation Details:

Title: TUSCANY Study demonstrates safety and efficacy of tuspetinib plus standard of care venetoclax and azacitidine in patients with newly diagnosed AML ineligible for induction chemotherapy

Acute Myeloid Leukemias: Investigational Drug and Cellular Therapies: Poster I
Session Date: December 6, 2025
Session Time: 5:30 PM - 7:30 PM
Presentation Time: 5:30 PM - 7:30 PM
Room: OCCC - West Halls B3-B4
Publication Number: 1645

The abstract accepted for presentation can be viewed online at the ASH conference website here, and will appear in the November supplemental issue of Blood. Please note that the actual presentation will include more recent updates and additional data not found in the abstract.

The poster presentation will be available on the Aptose website 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 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 therapeutic potential and safety profile of tuspetinib (including the triplet therapy) and its clinical development, 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. Many factors could cause our actual results, performance or achievements be materially different from any future results, performance or achievements described in this press release. Such factors could 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 Pietropaolo
Corporate Communications & Investor Relations
201-923-2049
spietropaolo@aptose.com

• Addition of TUS to VEN+AZA achieves CR/CRh responses in all (6/6, 100%) patients treated at the higher dose levels of 80 mg and 120 mg TUS, exceeding the 66% rate expected from VEN+AZA alone
  

• CR/CRh responses in 7/8 (88%) FLT3 wildtype AML, representing 70% of AML population
  

• TUS+VEN+AZA achieves CR/CRh and MRD-negativity in TP53-mutated (2/2), RAS-mutated (1/1) and FLT3-ITD (2/2) AML patients to date
  

• TUS+VEN+AZA is well tolerated with no DLT, differentiation syndrome, QTc prolongation, or prolonged myelosuppression at any dose level to date in newly diagnosed AML patients
  

• TUS+VEN+AZA is being developed as a safe and mutation agnostic frontline therapy for AML
  

• Dosing with 160 mg TUS is now ongoing
  

SAN DIEGO and TORONTO, Oct. 16, 2025 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (OTC: APTOF, TSX: APS), a clinical-stage precision oncology company developing the tuspetinib (TUS)-based triple drug frontline therapy to treat patients with newly diagnosed AML, today announced that data from the ongoing TUSCANY trial of tuspetinib in combination with venetoclax and azacitidine (TUS+VEN+AZA) are being presented in a poster presentation, “TUSCANY Study of Safety and Efficacy of Tuspetinib plus Standard of Care Venetoclax and Azacitidine in Study Participants with Newly Diagnosed AML Ineligible for Induction Chemotherapy,” at the European School of Haematology (ESH) 7^th International Conference on Acute Myeloid Leukemia “Molecular and Translational”: Advances in Biology and Treatment, being held from October 16-18, 2025 in Estoril, Portugal. Data to date from 10 patients in the TUSCANY trial across all three cohorts, 40 mg, 80 mg or 120 mg TUS dose in TUS+VEN+AZA, reveal promising clinical safety and antileukemic activity and support the use of TUS with standard of care treatment across a broad range of AML populations, including those carrying adverse mutations regardless of FLT3 mutation status.

The TUS+VEN+AZA triplet is being developed as a safe and well-tolerated, mutation agnostic frontline therapy to treat large, mutationally diverse populations of newly diagnosed AML patients who are ineligible to receive induction chemotherapy. Across all dose cohorts to date, no significant safety concerns or dose limiting toxicities (DLTs) have been observed in the TUSCANY trial, including no prolonged myelosuppression in Cycle 1 of subjects in remission, no reports of drug-related QTc prolongation or differentiation syndrome (DS), no CPK elevation and no treatment-related deaths. Dosing has begun at the 160 mg TUS dose level.

“We have observed that TUS can be safely added to a backbone VEN+AZA without needing to reduce the dose of these standard-of-care drugs. The activity we have observed with the TUS triplet in the first 10 patients has exceeded our expectations with 9 achieving complete remissions and 7 demonstrating MRD-negativity by central flow cytometry,” said Rafael Bejar, M.D., Ph.D., Chief Medical Officer of Aptose. “In addition, these remissions are happening in diverse genetic subtypes including those with unmutated FLT3, FLT3-ITD, NPM1c, biallelic TP53 with complex karyotype, RAS, or myelodysplasia related mutations, making this a truly mutation agnostic therapy.”

Data highlights:

• TUS in combination with standard dosing of VEN+AZA has been well tolerated with no DLT, no treatment-related deaths, no differentiation syndrome, no QTc prolongation, no prolonged myelosuppression after remission in Cycle 1, and no CPK elevations reported at any dose levels to date in these newly diagnosed AML patients.
  

• Addition of TUS to VEN+AZA achieved CR/CRh responses in 6/6 (100%) patients treated at the higher dose levels of 80 mg and 120 mg TUS, exceeding the 66% rate expected from VEN+AZA alone.
  

• Overall, TUS+VEN+AZA CR/CRh responses were observed in 9/10 (90%) patients.
  

• 7 of 8 (88%) CR/CRh responses in FLT3 wildtype AML, representing 70% of AML population.

• TUS+VEN+AZA MRD-negativity noted in 7/9 (78%) responding patients by central flow cytometry.

• CR/CRh responses achieved across diverse mutational subtypes including: unmutated FLT3, FLT3-ITD, NPM1c, biallelic TP53 with complex karyotype, RAS, and myelodysplasia related mutations.

• Dosing at the TUS 160 mg dose level is now ongoing.
  

See the ESH poster presentation here.

TUSCANY: TUS+VEN+AZA Triplet Phase 1/2 Study

The tuspetinib-based TUS+VEN+AZA triplet therapy is being advanced in the TUSCANY Phase 1/2 trial with the goal of creating an improved frontline therapy for newly diagnosed AML patients that is active across diverse AML populations, durable, and well tolerated.

The TUSCANY triplet Phase 1/2 study, being conducted at 10 leading U.S. clinical sites by elite clinical investigators, is designed to test various doses and schedules of TUS in combination with standard dosing of AZA and VEN for patients with AML who are ineligible to receive induction chemotherapy. A convenient, once daily oral agent, TUS is being administered in 28-day cycles. Multiple U.S. sites are enrolling in the TUSCANY trial with anticipated enrollment of 18-24 patients by the end of 2025. Data will be released as it becomes available.

More information on the TUSCANY Phase 1/2 study can be found on www.clinicaltrials.gov (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 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 therapeutic potential and safety profile of tuspetinib (including the triplet therapy) and its clinical development, goals, the anticipated enrollment rate in the TUSCANY trial and the timing thereof, 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. 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 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 Pietropaolo
Corporate Communications & Investor Relations
201-923-2049
spietropaolo@aptose.com