Aptose Biosciences Inc. (“Aptose,” “the Company,” “we,” “us,” or “our”) is a science-driven, clinical-stage biotechnology company committed to the development and commercialization of precision medicines addressing unmet clinical 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 executive offices are located in San Diego, California, and our head office is located in Toronto, Canada.

We are advancing targeted agents to treat life-threatening hematologic cancers that, in most cases, are not elective for patients and require immediate treatment. We have two clinical-stage investigational products for hematological malignancies: tuspetinib, an oral, potent myeloid kinase inhibitor, and luxeptinib, an oral, dual lymphoid and myeloid kinase inhibitor.

Since our inception, we have financed our operations and technology acquisitions primarily from equity financing, proceeds from the exercise of warrants and stock options, and interest income on funds held for future investment. Our uses of cash for operating activities have primarily consisted of salaries and wages for our employees, facility and facility-related costs for our offices and laboratories, fees paid in connection with preclinical and clinical studies, licensing fees, drug manufacturing costs, laboratory supplies and materials, and professional fees.

Management recognizes that in order for us to meet our capital requirements, and continue to operate, additional financing will be necessary. We plan to raise additional funds to fund our business operations but there is no assurance that such additional funds will be available for us to finance our operations on acceptable terms, if at all. The Company's current cash, cash equivalents and investments will enable the support of operations through August 2024. These conditions raise substantial doubt about the Company’s ability to continue as a going concern, see Note 2(a). The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Our ability to raise additional funds could be affected by adverse market conditions, the status of our product pipeline, possible delays in enrollment in our trial, and various other factors and we may be unable to raise capital when needed, or on terms favorable to us. If necessary funds are not available, we may have to delay, reduce the scope of, or eliminate some of our development programs, potentially delaying the time to market for any of our product candidates.

We do not expect to generate positive cash flow from operations for the foreseeable future due to the early stage of our clinical trials. It is expected that negative cash flow will continue until such time, if ever, that we receive regulatory approval to commercialize any of our products under development and/or royalty or milestone revenue from any such products exceeds expenses.

Our cash needs for the next twelve months include estimates of the number of patients and rate of enrollment of our clinical trials, the amount of drug product that we will require to support our clinical trials, and our general corporate overhead costs to support our operations, and our reliance on our manufacturers. We have based these estimates on assumptions and plans which may change and which could impact the magnitude and/or timing of operating expenses and our cash runway, See Note 2(a).

The Company's financial statements are prepared using generally accepted accounting principles in the United States of America applicable to a going concern which contemplates the realization of assets and liquidation of liabilities in the normal course of business. As of March 31, 2024, the Company had positive shareholder's equity of $0.1 million (December 31, 2023 negative shareholder's equity of $2.9 million); an accumulated deficit of approximately $525.2 million (December 31, 2023, $515.5 million); cash and cash equivalents and investment balances of approximately $9.3 million (December 31, 2023, $9.3 million); and negative working capital of approximately $0.3 million (December 31, 2023, negative working capital of $3.4 million). Management recognizes that in order to meet the capital requirements, and continue to operate, additional financing will be necessary. The Company plans to raise additional funds to fund our business operations through equity financing under the 2022 ATM Facility and other financing activities, as further described in Note 11 and Note 13. Management continues considering other options for raising capital including debt, equity, collaborations, and reorganization to reduce operational expenses. However, given the impact of the financial markets and the matter in Note 13, Subsequent events, that may impact the Company's ability to raise financing in the capital markets, the Company may be unable to access financing when needed. As such, there can be no assurance that the Company will be able to obtain additional liquidity when needed or under acceptable terms, if at all. These conditions raise substantial doubt about the Company’s ability to continue as a

going concern. The financial statements do not include any adjustments that might result from the outcome of this uncertainty. For information about financing events and the regulatory matter that may impact the Company's ability to raise financing in the capital markets which arose subsequent to March 31, 2024, see Note 13, Subsequent events.

On May 23, 2023, during the Aptose Annual and Special Meeting of Shareholders, our shareholders voted to approve special resolutions providing for an amendment to our articles of incorporation to effect a reverse share split of our outstanding Common Shares, at a ratio in the range of 1-for-10 to 1-for-20. Our Board of Directors then approved a ratio of 1-for-15 on May 23, 2023. On May 24, 2023, we filed articles of amendment under the Canada Business Corporations Act ("CBCA") to give effect to the reverse stock split (consolidation) of our Common Shares on the basis of one post-consolidation Common Share for each 15 pre-consolidation Common Shares (the “Reverse Stock Split”). The Common Shares commenced trading on a post-Reverse Stock Split basis at market open on Tuesday, June 6, 2023. All references in this report to historical Common Share prices, numbers of Common Shares, and earnings per share calculations have been presented to reflect the effect of the Reverse Stock Split.