• 32 AML patients dosed across 40 mg, 80 mg, 120 mg and 160 mg TUS with TUS+VEN+AZA triplet

• Composite complete response (CRc) rate in evaluable patients across all dosing groups was 86.2%

• MRD-negativity in patients who achieved a CR/CRh response was 86.4%

• AML patients with diverse genetics, including TP53-mutated, complex karyotypes, and unmutated FLT3, safely achieved responses and MRD negativity
  
  

SAN DIEGO and TORONTO, June 15, 2026 (GLOBE NEWSWIRE) -- Aptose Biosciences Inc. (“Aptose” or the “Company”) (TSX: APS; OTC: APTOF), a clinical-stage precision oncology company, announced that data from its Phase 1/2 TUSCANY trial in newly diagnosed AML patients treated with tuspetinib (TUS) in combination with standard of care dosing venetoclax and azacitidine (TUS+VEN+AZA triplet) was presented yesterday in an oral presentation at the European Hematology Association Congress (EHA 2026) in Stockholm, Sweden.

The TUS+VEN+AZA triplet is being developed as a mutation agnostic frontline therapy to treat large, mutationally unrestricted and diverse populations of newly diagnosed AML patients who are ineligible to receive induction chemotherapy. Nikolai Podoltsev, MD, PhD, Associate Professor Medical Oncology & Hematology, Clinical Director, Malignant Hematology, Yale School of Medicine, and an investigator in the TUSCANY study, reported updated safety and efficacy data from the 80 mg and 120 mg dose cohorts, as well as new data from the 160 mg dose of TUS in the TUS+VEN+AZA triplet.

“While there have been recent successes with targeted therapy in AML treatment, our multi-targeted approach with tuspetinib in combination is showing significant efficacy across mutations that have been historically difficult to treat, including TP53 mutations, where we thus far have achieved CRs in all of the four subjects at the highest dose cohort,” said Rafael Bejar, MD, PhD, Chief Medical Officer, Aptose. “As a safe and effective inhibitor of multiple growth factor signaling pathways, the TUS+VEN+AZA triplet is a first line combination therapy with the potential to improve outcomes in nearly all AML populations.”

The oral presentation at EHA included updated safety, complete remission, minimal residual disease (MRD) assessments, and longer duration of follow-up:

Presentation title:  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 

Presenter:   Nikolai Podoltsev, MD, PhD, Associate Professor (Medical Oncology & Hematology), Department of Internal Medicine; Clinical Director, Malignant Hematology, Associate Program Director, Hematology / Medical Oncology Fellowship Program, Yale School of Medicine

Key findings:

• 32 (29 response evaluable), newly diagnosed AML patients have received the TUS+VEN+AZA combination:
  • 4 received the 40 mg dose of TUS, 12 received the 80 mg dose of TUS, 3 received the 120 mg dose of TUS, and 13 received the 160 mg dose
    
    
• The overall CRc rate across dose levels in response evaluable (29) patients was 86.2%.
  • The MRD negative rate among all patients dosed was 62.5%; MRD negative rate in CR/CRh patients was 86.2%.
    
    
• At the 160 mg TUS dose level (n=13):
  • The overall CRc rate was 76.9% (10 of 13 patients), including 8 of 11 (72.7%) with unmutated (or wildtype) FLT3
    100 % composite complete remission in all 4 patients with TP53-mutation with complex karyotype (TP53-mut/CK)
    
    
• Regardless of mutation status, TUS is active in newly diagnosed AML patients
  • MRD-negative responses achieved across diverse genetic populations, including adverse TP53 mutations and CK
  • Responses continue to evolve with 19 subjects remaining on treatment, including 6 that moved on to stem cell transplantation
    
    
• TUS can be administered safely with standard-of-care dosing of VEN/AZA
  • TUS PK properties were not significantly altered by VEN, AZA, antifungals or food
  • No treatment-related deaths
  • No treatment-related adverse events of QT_c prolongation, CPK elevations or differentiation syndrome

Abstracts are available on the EHA2026 website here. The presentation is available on the Aptose website 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 clinical study 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. Earlier APTIVATE trials of TUS as a single agent and in combination as TUS+VEN demonstrated favorable safety and broad activity in diverse relapsed or refractory (R/R) AML populations that went beyond the more prognostically favorable NPM1 and IDH mutant subgroups. Indeed, responses were also in R/R AML patients with highly adverse TP53 and RAS mutations, and those with mutated or unmutated (wildtype) FLT3 genes.

The TUSCANY 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.

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, 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 SecuritExchange 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

As previously disclosed in the Company’s news release dated November 19, 2025 (here), upon the completion of the Arrangement, Hanmi 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 and shareholders of Aptose, 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 for the period immediately preceding entering into the Arrangement Agreement.

The Company also announced that it has received an additional advance of US$2.0 million from Hanmi as part of a US$11.9 million loan amended facility agreement (“Facility Agreement”) announced prior on September 22, 2025 (here). To date, Aptose has received an aggregate of US$9.9 million under the Facility Agreement. Aptose expects to receive the final advance of US$2.0 million under the Facility Agreement in the coming days. These advances support Aptose and enable uninterrupted continuance of the TUSCANY clinical trial with tuspetinib in combination with venetoclax and azacitidine for the frontline treatment of newly diagnosed AML.

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 includes, among other things, statements relating to the receipt of certain Korea regulatory approvals and the timing of closing of 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

“Our TUSCANY clinical trial of tuspetinib in combination with venetoclax (VEN) and azacitidine (AZA) for frontline treatment of newly diagnosed acute myeloid leukemia (AML) continues to deliver robust safety and response data, and we’re pleased that an update of our TUS+VEN+AZA triplet clinical data has been selected for an oral presentation at the upcoming EHA2026 Congress in June,” said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer of Aptose. “Likewise, we are pleased that the expected acquisition of the Company by Hanmi Pharmaceutical will allow the continued development of tuspetinib for AML patients in need of a well-tolerated and broadly active therapy to treat those with even the most adverse of mutation profiles, including those with TP53-mutated disease.”

Key Corporate Highlights    

• Update on Acquisition of Aptose by Hanmi Pharmaceutical – On April 30, 2026, Aptose announced that the closing of the previously announced arrangement (the “Arrangement”) with Hanmi Pharmaceutical Co. Ltd. (“Hanmi”) and HS North America Ltd., a wholly owned subsidiary of Hanmi (together with Hanmi, the “Hanmi Purchasers”), has been delayed as certain Korean regulatory approvals pertaining to the Arrangement remain under way (press release here). The parties do not anticipate that the regulatory reviews will prevent closing and continue to work toward completing the Arrangement that they target for the month of May. The Company will provide a further update when available.
  
  Under the terms of the Arrangement Agreement, Aptose shareholders, other than the Hanmi Purchasers and their respective affiliates that hold any common shares of Aptose (the “Common Shares”), 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) at the date of the execution of the Arrangement Agreement. 

• Aptose Clinical Data to be Presented at EHA in Oral Presentation – Data from Aptose’s Phase 1/2 TUSCANY trial in newly diagnosed patients treated with tuspetinib (TUS) in combination with standard of care dosing venetoclax and azacitidine (TUS+VEN+AZA triplet) has been selected for oral presentation at the European Hematology Association Congress (EHA 2026), being held June 11-14, 2026, in Stockholm, Sweden. The TUS+VEN+AZA triplet is being developed as a safe and mutation agnostic frontline therapy to treat large, mutationally diverse populations of newly diagnosed AML patients who are ineligible to receive induction chemotherapy. As reported prior, the first two dose cohorts at 40 mg of TUS or 80 mg of TUS in the TUS+VEN+AZA triplet, demonstrated safety, complete remissions, and MRD negativity across patients with diverse mutations, including TP53-mutated/CK AML and FLT3-wildtype AML patients. The oral presentation at EHA will include updated data at the 80 mg and 120mg dose levels, as well as new data from the 160 mg dose of TUS, updated safety, complete remissions, minimal residual disease (MRD) and other clinical findings with a longer duration of follow up.
  
  EHA session title: s446 Novel treatments in AML
  
  Presentation title: 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
  
  Live session date & time: June 14, 2026 (11:00 – 12:15 CEST)
• Aptose Returns Luxeptinib License Rights to CGI – Aptose and CGI Invites Co., Ltd. (“CGI”) have entered into a Termination of License Agreement relating to the exclusive license originally granted to Aptose under a 2016 agreement (updated in 2018) whereby Aptose returned the license rights to CG-806 to CGI. Under the license agreement, Aptose held exclusive rights from CGI to develop and commercialize the compound CG-806, also known as luxeptinib (LUX).
  

Net loss for the three months ended March 31, 2026 of $7.6 million increased $2.1 million as compared with a net loss of $5.5 million for the comparable period in 2025. 

• Total cash and restricted cash as of March 31, 2026 was $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 cost reduction efforts to extend cash runway.
  
  
• As of May 8, 2026, there were 2,552,429 Common Shares issued and outstanding. In addition, there were 37,083 Common Shares issuable upon the exercise of outstanding stock options and 1,139,085 Common Shares issuable upon the exercise of outstanding warrants.
  
  

RESEARCH AND DEVELOPMENT EXPENSES

Research and development expenses for the three months ended March 31, 2026 and 2025 were as follows:

Research and development expenses increased by $1.2 million to $3.6 million for the three months ended March 31, 2026 as compared to $2.4 million for the comparable period in 2025. 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 increased by $1.4 million to $2.9 million for the three months ended March 31, 2026 compared to $1.5 million for the comparable period in 2025. The higher program costs for tuspetinib in the current period are attributable to increased costs associated with the TUSCANY study as we continue the advancement of tuspetinib.
  
  
• Program costs for luxeptinib decreased by approximately $0.1 million during the three months ended March 31, 2026 compared to the comparable period in 2025 due to a decrease in clinical trial costs as the trial is being wound down.
  
  
• Personnel-related expenses remained relatively consistent during the three months ended March 31, 2026 compared to the comparable period in 2025 as headcount for research and development personnel remained consistent between periods.
  
  
• Stock-based compensation decreased by $0.1 million for the three months ended March 31, 2026 compared to the comparable period in 2025. 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 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, development 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 and advances by Hanmi, the Company’s cash runway, the planned acquisition by Hanmi and its expected 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: our ability to obtain the capital required for research and operations; the completion of the Hanmi acquisition; 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

Transaction Details

As previously disclosed in the Company’s news release dated November 19, 2025 (here), upon the completion of the Arrangement, Hanmi 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 and shareholders of Aptose, 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 for the period immediately preceding entering into the Arrangement Agreement.

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 includes, among other things, statements relating to the receipt of certain Korea regulatory approvals and the timing of closing of 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, 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