Ms. Susan Pietropaolo reports

APTOSE TO HOLD CLINICAL UPDATE AND KOL DATA REVIEW OF AML DRUG TUSPETINIB ON MONDAY, OCTOBER 30TH

Aptose Biosciences Inc. will provide a clinical update on Monday, Oct. 30, 2023, at 8:30 a.m. Eastern Time, in conjunction with poster presentations at the European School of Haematology (ESH) sixth international conference, "Acute Myeloid Leukemia 'Molecular and Translational:' Advances in Biology and Treatment," being held Oct. 29, 2023, to Oct. 31, 2023, in Estoril, Portugal.

The webcast event will include a comprehensive review of up-to-date clinical data for Aptose's lead compound tuspetinib and will feature Dr. Naval Daver, MD, professor, director, leukemia research alliance program, Department of Leukemia, the University of Texas MD Anderson Cancer Center, Houston, Tex. Dr. Daver is the lead investigator on Aptose's Aptivate trial and is recognized for significant achievements in the development of novel AML treatments, including several combination therapies.

Tuspetinib (TUS), a once-daily oral tablet, is a precision targeted myeloid kinase inhibitor that suppresses a select handful of kinases known to drive the proliferation of acute myeloid leukemia (AML) but avoids other kinases that can compromise safety. Tuspetinib as a single agent was well tolerated and highly active among relapsed or refractory (R/R) AML patients with a diversity of adverse genotypes and delivered a 42-per-cent CR/CRh across evaluable venetoclax (VEN) naive patients at the 80-milligram daily RP2D. Tuspetinib also is being studied in combination with venetoclax (VEN) in the Aptivate international phase 1/2 expansion trial in R/R AML patients. The TUS/VEN doublet has been well tolerated and achieved multiple responses in patients who previously failed venetoclax (prior-VEN failure AML), including prior-VEN failure patients who also previously failed FLT3 inhibitors, all of whom represent emerging populations of high unmet medical need. Notably, tuspetinib targets venetoclax resistance mechanisms that may resensitize prior-VEN failure patients to venetoclax.

Aptose clinical update details

Date and time:  Monday, Oct. 30, 2023, 8:30 a.m. ET

Participant webcast:  A webcast link is available.

The slides will be available on Aptose's website and the webcast of the presentation will be archived shortly after the conclusion of the event.

Poster presentations

As announced prior, the Aptose poster presentations at ESH are listed below. Note that the poster presentations will include additional data not found in the abstracts. The posters accepted for presentation are listed below and can be viewed beginning Oct. 29, 2023, on site at the ESH poster exhibit hall and on-line on the Aptose website:

• Tuspetinib myeloid kinase inhibitor safety and efficacy as monotherapy and combined with venetoclax in phase 1/2 trial of patients with relapsed or refractory (R/r) acute myeloid leukemia (AML);
• Tuspetinib oral myeloid kinase inhibitor creates synthetic lethal vulnerability to venetoclax.

About Aptose Biosciences Inc.

Aptose Biosciences is a clinical-stage biotechnology company committed to developing precision medicines addressing unmet medical needs in oncology, with an initial focus on hematology. The company's small-molecule cancer therapeutics pipeline includes products designed to provide single-agent efficacy and to enhance the efficacy of other anti-cancer therapies and regimens without overlapping toxicities. The company has two clinical-stage oral kinase inhibitors under development for hematologic malignancies: tuspetinib (HM43239), an oral, myeloid kinase inhibitor being studied as monotherapy and in combination therapy in the Aptivate international phase 1/2 expansion trial in patients with relapsed or refractory acute myeloid leukemia (AML); and luxeptinib (CG-806), an oral, dual lymphoid and myeloid kinase inhibitor in phase 1 a/b stage development for the treatment of patients with relapsed or refractory hematologic malignancies.

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