The Company has authorized share capital of an unlimited number of Common Shares.

(i) 2025 Committed Equity Facility

On February 7, 2025, the Company and Keystone entered into the Purchase Agreement, which provides that subject to the terms and conditions set forth therein, the Company may sell to Keystone up to the greater of (i) $25 million of the Common Shares and (ii) the Exchange Cap (as defined below) (subject to certain exceptions provided in the Purchase Agreement) (the “Total Commitment”), from time to time during the two year term of the Purchase Agreement. Additionally, on February 7, 2025, the Company and Keystone entered into a registration rights agreement (the “Registration Rights Agreement”), pursuant to which the Company agreed to file a registration statement with the SEC covering the resale of Common Shares that are issued to Keystone under the Purchase Agreement. Upon entering into the Purchase Agreement, the Company agreed to issue to Keystone an aggregate of 8,020 Common Shares (the “Commitment Shares”) as consideration for Keystone’s commitment to purchase Common Shares upon the Company’s direction under the Purchase Agreement. The Company also agreed to pay Keystone up to $25,000 for its reasonable expenses under the Purchase Agreement.

(ii) 2025 At-The-Market Facility

On February 3, 2025 the Company and A.G.P./Alliance Global Partners (“AGP”) entered into a sales agreement whereby the Company, may from time to time, sell Common Shares having an aggregate offering value of up to $1.0 million through AGP on Nasdaq (the “2025 ATM Facility”). Costs associated with the proceeds consist of 3% cash commission. Up to February 12, 2025, the Company issued 137,000 Common Shares under this 2025 ATM Facility at an average price of $7.31 per share for gross proceeds of $1.0 million ($0.8 million net of share issuance costs).

(iii) November 2024 Public Offering

On November 25, 2024, the Company completed a reasonable best efforts public offering (the “November 2024 Public Offering”) with participation from the Company's CEO and existing and new healthcare focused investors for the purchase and sale of 1,333,333 Common Shares at a price of $6.00 per share and warrants to purchase up to 666,599 Common Shares (the “November 2024 Investor Warrants”). The November 2024 Investor Warrants have an exercise price of $6.00 per share, were exercisable immediately and will expire five years from the issuance date. In connection with the November 2024 Public Offering, the Company received aggregate gross proceeds of $8.0 million, before deducting placement agent fees and other offering expenses of approximately $1.1 million, comprised of placement agent fees of $0.6 million and professional fees of $0.5 million. Additionally, AGP, the lead placement agent engaged by the Company, received 53,333

warrants, each with an exercise price of $8.25 (the “AGP Warrants”). The AGP Warrants were exercisable immediately and will expire five years from November 25, 2024.

(iv) September 2024 Common Share Issuance

On September 5, 2024, the Company held a Special Meeting of Shareholders pursuant to which, shareholders voted to authorize, for purposes of complying with Nasdaq Listing Rule 5635(d), the issuance of Common Shares underlying certain warrants in an amount equal to or in excess of 20% of our Common Shares outstanding immediately prior the issuance of such warrants pursuant to the June 2024 Registered Direct Offering. On September 11, 2024, the Company issued 68,500 Common Shares upon the exercise of 68,500 Pre-Funded Warrants for cash proceeds of $2,000 at an exercise price of $0.03.

(v) June 2024 Registered Direct Offering and Concurrent Private Placement

On June 3, 2024, the Company completed the Registered Direct Offering for the purchase and sale of 60,000 Common Shares at a purchase price of $34.50 per Common Share and 68,500 pre-funded warrants (the “Pre-Funded Warrants”) with an exercise price of $0.03 per Pre-Funded Warrant. Each Pre-Funded Warrant was exercisable immediately and expires on June 25, 2029.

In a concurrent private placement, Aptose issued unregistered series A warrants to purchase up to 128,500 Common Shares (“Series A Warrants”) and series B warrants to purchase up to 128,500 Common Shares (“Series B Warrants”), each at an exercise price of $34.50 per share. The series A and series B unregistered warrants became exercisable beginning on the effective date of shareholder approval of the issuance of the shares issuable upon exercise of the warrants, which was obtained on September 5, 2024. The Series A Warrants expire five years from September 5, 2024 and the Series B Warrants expire March 5, 2026.

The gross proceeds to the Company from the Registered Direct Offering were approximately $4.4 million, less cash transaction costs of approximately $0.4 million, which include placement agent and other professional fees. In addition, H.C. Wainwright (“HCW”), the lead placement agent engaged by the Company for the Registered Direct Offering, received 6,423 warrants, each with an exercise price of $43.13 (the “HCW Warrants”). The HCW warrants were exercisable beginning on September 5, 2024 and will expire on June 3, 2029.

(vi) January 2024 Public Offering

On January 30, 2024, the Company completed a public offering (the “January 2024 Public Offering”) of 188,304 Common Shares (including 24,561 Common Shares issued pursuant to a full exercise by the underwriter, Newbridge Securities Corporation (“Newbridge”), of its over-allotment option at a purchase price of $51.30 per Common Share, for aggregate gross proceeds of $9.7 million, less cash transaction costs of $1.6 million. The Company also issued share purchase warrants underlying a total of 188,174 Common Shares to each investor who participated in the January 2024 Public Offering (the “January 2024 Investor Warrants”). Each January 2024 Investor Warrant has an exercise price of $51.30 per share and is exercisable immediately upon issuance. The January 2024 Investor Warrants will expire January 30, 2029.

Additionally, in connection with the January 2024 Public Offering, the Company issued share purchase warrants underlying a total of 18,084 Common Shares to Newbridge as compensation payable thereto, with each warrant having an exercise price of $64.13 per share and being exercisable beginning on July 30, 2025 and expiring on January 30, 2028. The issue-date fair value of all warrants issued to Newbridge in connection with the January 2024 Public Offering and the January 2024 Private Placements (the “Newbridge Warrants”) was recorded as additional transaction costs, with a reduction to Common Shares and a corresponding increase to additional paid-in capital.

(vii) Hanmi Private Placement

Concurrently with the January 2024 Public Offering, the Company completed a private placement with Hanmi (the “Hanmi Private Placement”) of 70,175 Common Shares at a price of $57.00 per Common Share, representing an 11% premium over the price of the Common Shares issued as part of the January 2024 Public Offering, for gross proceeds of $4.0 million, less cash transaction costs of $0.3 million. Also, as part of the January 2024 Private Placement, the Company issued to Hanmi, Common Share purchase warrants underlying 77,972 of our Common Shares (the “Hanmi Warrants”). Each Hanmi Warrant has an exercise price of $51.30 per Common Share and was exercisable immediately upon issuance. The Hanmi Warrants will expire January 31, 2029.

(viii) Hanmi 2023 Equity Investment

On August 10, 2023, the Company entered into a binding term sheet with Hanmi whereby Hanmi agreed at their sole discretion to invest up to a maximum of $7 million in Aptose, limited to a total ownership of 19.99% of Aptose by Hanmi.

On September 6, 2023, the Company entered into a subscription agreement with Hanmi, pursuant to which the Company agreed to sell 22,281 Common Shares to Hanmi for proceeds of $3 million.

(ix) 2023 Committed Equity Facility

On May 25, 2023, the Company and Keystone Capital Partners, LLC ("Keystone") entered into a committed equity facility, (the "2023 Committed Equity Facility"), which provides that subject to the terms and conditions set forth therein, the Company may sell to Keystone up to the lesser of (i) $25.0 million of the Common Shares and (ii) a number of Common Shares equal to 19.99% of the Common Shares outstanding immediately prior to the execution of the 2023 Committed Equity Facility Agreement. Additionally, on May 25, 2023, the Company entered into a Registration Rights Agreement with Keystone, pursuant to which the Company agreed to file a registration statement with the SEC covering the resale of Common Shares that are issued to Keystone under the 2023 Committed Equity Facility. This registration statement became effective on June 30, 2023 and the 2023 Committed Equity Facility commencement date was July 12, 2023 (the "Commencement Date").

Upon entering into the 2023 Committed Equity Facility, the Company agreed to issue to Keystone an aggregate of 838 Common Shares (the “Commitment Shares”) as consideration for Keystone’s commitment to purchase Common Shares upon the Company’s direction under the 2023 Committed Equity Facility. The Company issued 251 Common Shares, or 30% of the Commitment Shares, on the date of the 2023 Committed Equity Facility Agreement. An additional 251 Common Shares, or 30% of the Commitment Shares, were issued to Keystone in October 2023.

For the three months ended March 31, 2024, the Company's issuance of Common Shares to Keystone consisted of the 336 Commitment Shares issued in January 2024. Since May 25, 2023 to April 2024, the time the Committed Equity Facility was terminated, the Company's issuance of Common Shares to Keystone comprised of an aggregate of 41,019 Common Shares at an average price of $68.10 per Common Share for aggregate gross cash proceeds of $2.8 million and 838 Commitment Shares.

From May 25, 2023 to the termination of the Committed Equity Facility, the Company recognized $168,000 of financing costs associated with professional fees. In April 2024, the Company's issuances of Common Shares to Keystone reached the Total Commitment of the Committed Equity Facility, i.e., 19.99% of the Common Shares outstanding immediately prior to the execution of the 2023 Committed Equity Facility Agreement.

(x) 2022 At-The-Market Facility ("ATM")

On December 9, 2022, the Company entered into an equity distribution agreement pursuant to which the Company may, from time to time, sell Common Shares having an aggregate offering value of up to $50 million through Jones Trading Institutional Services LLC ("Jones Trading") on Nasdaq (the "2022 ATM Facility"). During the three months ended March 31, 2024, the Company did not issue shares under the 2022 ATM Facility. On May 30, 2024, the Company terminated the 2022 ATM Facility. Since inception to May 30, 2024, the date the Company terminated the 2022 ATM Facility, the Company raised a total of $2.0 million of gross proceeds ($2.0 million net of share issuance costs) under the 2022 ATM Facility. Costs associated with the proceeds consisted of a 3% cash commission.

The effects of any potential exercise of the Company’s stock options outstanding during the three months ended March 31, 2025 and 2024 have been excluded from the calculation of diluted loss per share, since such securities would be anti‑dilutive.