On April 2, 2024, the Company received a letter (the “Notification Letter”) from Nasdaq stating that the Company was not in compliance with Nasdaq Listing Rule 5550(b)(1) (the “Rule”) because the stockholders’ equity of the Company as of December 31, 2023, as reported in the Company’s Annual Report on Form 10-K, was below the minimum requirement of $2.5 million (the "Stockholders’ Equity Requirement"). The Company submitted a Compliance Plan on May 17, 2024.

On June 28, 2024 , the Company received a letter from Nasdaq stating that Nasdaq had granted the Company an extension until September 30, 2024 to regain compliance with the Rule. On August 1, 2024 the Company filed a preliminary S-1 prospectus to raise financing as part of its Compliance Plan, in addition to funds raised in the 10a.(i), June 2024 Registered Direct Offering.

On July 16, 2024, the Company received a deficiency letter (the “Deficiency Letter”) from the Staff of The Nasdaq Stock notifying the Company that, for the prior thirty consecutive business days, the closing bid price for the Company’s Common Shares have been below the minimum $1.00 per share required for continued listing on Nasdaq pursuant to Nasdaq Listing Rule 5550(a)(2) (the “Minimum Bid Price Requirement”). The Deficiency Letter had no immediate effect on the listing of the Company’s Common Shares, and its Common Shares will continue to trade on Nasdaq. The Company’s Common Shares continue to trade on the Toronto Stock Exchange (“TSX”) under the symbol “APS.” The Company's listing on the TSX is independent and will not be affected by the Nasdaq listing status. The Company has been given 180 calendar days, or until January 13, 2025, to regain compliance with the Minimum Bid Price Requirement. If at any time before January 13, 2025, the bid price of the Company’s Common Shares closes at $1.00 per share or more for a minimum of 10 consecutive business days, the Staff will provide written confirmation that the Company has achieved compliance with the Minimum Bid Requirement. If the Company does not regain compliance with the Minimum Bid Price Requirement by January 13, 2025, the Company may, at Nasdaq's discretion, be afforded a second 180 calendar day period to regain compliance, but if Nasdaq does not grant such extension, the Company's common shares could be delisted from Nasdaq. To qualify for the extension, the Company will be required to meet the continued listing requirement for market value of publicly held shares and all other initial listing standards for Nasdaq, with the exception of the bid price requirement. The Company intends to monitor the closing bid price of its Common Shares and may, if appropriate, consider available options, including the possibility of seeking shareholder approval of a reverse stock split, to regain compliance with the Minimum Bid Price Requirement. However, there can be no assurance that the Company will be able to regain compliance with the Minimum Bid Price Requirement or will otherwise be in compliance with other Nasdaq Listing Rules.

As of September 30, 2024, the Company had not gained compliance with the requirement. The Company's stockholder's equity as of September 30, 2024 was negative $9.1 million.

On October 1, 2024, the Company received a staff determination letter from the Listing Department stating that the Company did not meet the terms of the extension because it did not complete its proposed financing initiatives to regain compliance. On October 8, 2024, the Company requested an appeal and hearing; such hearing is scheduled for November 21, 2024. The hearing request has automatically stayed Nasdaq’s delisting of the Company’s Common Shares pending the Panel’s decision. At or prior to the hearing, the Company plans to present to Nasdaq information demonstrating that it has regained compliance with the continued listing standards under the Nasdaq Listing Rules, or alternatively a plan to regain compliance and a request for an extension of time to effectuate the plan. Notwithstanding the foregoing, there can be no assurance that the Company will regain compliance with the continued listing standards under the Nasdaq Listing Rules, or that the Panel will grant the Company an extension of time to regain compliance, in the event the Company requests such an extension.

On October 30, 2024, the Company filed Amendment 1 to this S-1, see note 12, Subsequent Events.

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

(i) June 2024 Registered Direct Offering

On June 3, 2024, the Company closed a registered direct offering priced at-the-market under Nasdaq rules of 1,800,000 Common Shares at a purchase price of $1.15 per share and 2,055,000 pre-funded warrants at a purchase price of $1.149 per pre-funded warrant. Additionally, in a concurrent private placement, Aptose issued unregistered series A warrants to purchase up to 3,855,000 Common Shares and series B warrants to purchase up to 3,855,000 Common Shares, each at an exercise price of $1.15 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 will expire five years from September 5, 2024 and the series B warrants will expire eighteen months from September 5, 2024. The gross proceeds to the Company from the offering was approximately $4.43 million, before deducting the placement agent’s fees and other offering expenses. Financing costs of approximately $408 thousand included underwriting costs of 7% and professional fees. In addition, the underwriter received 192,750 warrants, each at an exercise price of $1.44. The unregistered warrants are exercisable on September 5, 2024 and will expire five years from September 5, 2024.

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 the Common Shares outstanding immediately prior the issuance of such warrants issued pursuant to that certain securities purchase agreement dated as of May 30, 2024 by and among the Company and certain institutional and accredited investors in connection with the Company’s registered direct offering and private placement which closed on June 3, 2024. On September 11, 2024, the Company issued 1,395,000 Common Shares upon the exercise of 1,395,000 Pre-Funded Warrants for a cash proceeds of $1 thousand at an exercise price of $0.001.

(ii) January 2024 Public Offering and Private Placement

On January 31, 2024, the Company announced the closing of a $9.7 million public offering (the “Public Offering”) and a $4 million private placement (the “Private Placement”) with Hanmi. The Public Offering comprised 5,649,122 Common Shares and warrants at a combined offering price of $1.71. This included 736,842 Common Shares and warrants pursuant to a full exercise by the underwriter of its over-allotment option. The Private Placement comprised 2,105,263 Common Shares sold at a price of $1.90, representing an 11% premium over the price of the Common Shares issued as part of the Public Offering. Nasdaq subsequently issued a letter to the Company regarding the value and the date of the Private Placement, as discussed in this note, below. Financing costs of approximately $1.4 million included underwriting costs of 7% and approximately $0.4 million in professional fees. The Company also issued Hanmi warrants to purchase Common Shares at an exercise price of $1.71 per Share.

On February 29, 2024, the Company received a deficiency letter (the “February Deficiency Letter”) from the Nasdaq Listing Qualifications Department of Nasdaq notifying the Company that the Company’s Private Placement violated Nasdaq Listing Rule 5635(d) because the Company did not obtain shareholder approval prior to such issuance. Nasdaq stated that the Private Placement involved the issuance of greater than 20% of the issued and outstanding Common Shares of the Company at a discount to the Nasdaq official closing price on January 25, 2024, the date of the subscription agreement between the Company and Hanmi. The February Deficiency Letter had no immediate effect on the listing of the Company’s Common Shares. In accordance with the Nasdaq Listing Rules, the Company was given 45 calendar days to submit a plan to regain compliance. The approval of the potential issuance of Common Shares in connection with the Hanmi investment, which would exceed 19.99% of the Corporation’s outstanding shares as of the closing date of the Hanmi investment, as required by Nasdaq listing rules, was approved at the June 2024 Annual and General meeting.

In response to a Deficiency Letter from Nasdaq received on February 29, 2024 regarding the private placement with Hanmi and the resulting claimed violation of Nasdaq Listing Rule 5635(d), the Company submitted a plan to regain compliance on April 15, 2024. On April 25, 2024, the Company received a letter from the Listing Qualifications Department (the “Staff”) of Nasdaq notifying the Company of the Staff’s determination that the Company had regained compliance with Nasdaq Listing Rule 5635(d) and the Staff has determined that the matter is now closed. Pursuant to the Company's plan to regain compliance, on April 26, 2024, the Company announced that it had amended the warrant agreement with Hanmi to prohibit the exercise of the Hanmi warrants in excess of the Nasdaq 19.99% limitation (the "Nasdaq 19.99% Cap"), unless shareholder approval is first obtained to exceed the Nasdaq 19.99% Cap.

(iii) Hanmi 2023 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 up 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 Corporation

agreed to sell 668,449 Common Shares to Hanmi for proceeds of $3 million. Hanmi held 2,989,415 Common Shares of Aptose as of September 30, 2024.

(iv) 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, we 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. with Keystone which respect to the 2023 Committed Equity Facility (subject to certain exceptions) (the “Total Commitment”), from time to time during the 24-month term of the 2023 Committed Equity Facility. 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 25,156 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 7,547 Common Shares, or 30% of the Commitment Shares, on the date of the 2023 Committed Equity Facility Agreement. An additional 7,547 Common Shares, or 30% of the Commitment Shares, were issued to Keystone in October 2023. In the nine months ended September 30, 2024, the Company's issuance of Common Shares to Keystone consisted of 10,062 Commitment Shares.

In the year ended December 31, 2023, the Company's issuance of Common Shares to Keystone comprised 720,494 Common shares sold to Keystone at an average price of $2.91 per Common share for cash proceeds of $2.1 million and 15,094 Commitment Shares. During the nine months ended September 30, 2024, the Company issued 510,101 Common Shares to Keystone at an average price of $1.36 per Common Share for cash proceeds of $694 thousand and 10,062 Commitment Shares. The Company recognized $82 thousand of financing costs associated with professional fees during the nine months ended September 30, 2024. Since inception 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 1,230,595 Common Shares at an average price of $2.27 per Common Share for aggregate gross cash proceeds of $2.8 million and 25,156 Commitment Shares. From inception to the termination of the Committed Equity Facility, the Company recognized $168 thousand 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.

(v) 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 current year up to May 30, 2024, the date on which the Company terminated the 2022 ATM Facility, the Company issued 81,591 Common Shares under this 2022 ATM Facility at an average price of $1.22 per share for gross proceeds of $100 thousand ($97 thousand net of share issuance costs). On May 30, 2024, the Company terminated the 2022 At-The-Market Facility. Since inception to May 30, 2024, the date the Company terminated the 2022 ATM Facility, the Company raised a total of $2.1 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-month and nine-month periods ended September 30, 2024, and September 30, 2023 have been excluded from the calculation of diluted loss per share, since such securities would be anti‑dilutive.