UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549



FORM 10-K/A

(AMENDMENT NO. 3)



(Mark one)



| | ☒ | ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
| | - | ------------------------------------------------------------------------------



For the fiscal year ended December 31, 2018.



| | ☐ | TRANSITION REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
| | - | ----------------------------------------------------------------------------------



Commission file number 001-3200



APTOSE BIOSCIENCES INC.

(Exact name of registrant as specified in its charter)



|Canada(State or other jurisdiction of incorporation or organization) |  | 98-1136802(I.R.S. Employer Identification No.)
|-------------------------------------------------------------------- |  | ----------------------------------------------



251 Consumers Road, Suite 1105

Toronto, Ontario,
Canada M2J 4R3

(Address of principal executive offices)



647-479-9828

(Registrant’s telephone number, including area code)





Securities registered pursuant to Section 12(b) of the Act:

Common Shares, without par value                  The
Nasdaq Stock Market



Securities registered pursuant to Section 12(g) of the Act:
None



Indicate by check mark if the registrant is a well-known seasoned
issuer, as defined in Rule 405 of the Securities Act. YES ☐ NO ☒



Indicate by check mark if the registrant is not required to file
reports pursuant to Section 13 or Section 15(d) of the Act. YES ☐ NO ☒



Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for
such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements
for the past 90 days. YES ☒ NO ☐



Indicate by check mark whether the registrant has submitted electronically
every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§229.405 of this chapter) during
the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). YES ☒
NO ☐













Indicate by check mark if disclosure of delinquent filers pursuant
to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge,
in definitive proxy or information statements incorporated by reference in Part III of this Form 10 K or any amendment to this
Form 10 K. ☒



Indicate by check mark whether the registrant is a large accelerated
filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definitions
of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging
growth company” in Rule 12b-2 of the Exchange Act. (Check one):



|Large accelerated filer ☐ |  | Accelerated filer ☐        
|------------------------- |  | ---------------------------
|Non-accelerated filer ☒   |  | Smaller reporting company ☒
|Emerging growth company ☒



If an emerging growth company, indicate by check mark if the registrant
has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided
pursuant to Section 13(a) of the Exchange Act. ☒



Indicate by check mark whether registrant is a shell company (as
defined in Rule 12b 2 of the Act). YES ☐ NO ☒



The aggregate market value of the voting stock and nonvoting common
equity held by non-affiliates computed by reference to the price at which the common equity was last sold, or the average bid and
asked prices of such common equity, as of June 30, 2018 was $134,370,583.00.



As of March 12, 2019, the registrant had 41,499,112 shares of common
stock outstanding.





EXPLANATORY NOTE



This Amendment No. 3 to Form 10-K (this “Amendment No. 3”) amends the Annual
Report on Form 10-K of Aptose Biosciences Inc. (the “Company”) for the year ended December 31, 2018, which was originally
filed with the U.S. Securities and Exchange Commission (the “SEC”) on March 12, 2019 (the “Original 10-K”)
and amended on March 26, 2019 and April 12, 2019. This Amendment No. 3 is being filed solely for the purpose of replacing Exhibit
10.10 and Exhibit 10.15 from the Original 10-K with a new Exhibit 10.10 and Exhibit 10.15 in connection with the SEC’s new
rules and procedures for exhibits containing immaterial, competitively harmful information and the Company’s withdrawal of
its confidential treatment request pertaining to the same exhibits. In addition, as required by Rule 12b-15 under the Securities
Exchange Act of 1934, new certifications by our principal executive officer and principal financial officer are filed as exhibits
to this Amendment No. 3. However, because no financial statements are contained within this Amendment No. 3, we are not including
new certifications pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.



Except as specifically provided otherwise herein, this Amendment No. 3 does not reflect
events occurring after March 12, 2019, the date of the filing of our Original 10-K, or modify or update those disclosures that
may have been affected by subsequent events. Accordingly, this Amendment No. 3 should be read in conjunction with the Original
10-K.

















PART IV.



ITEM 15. EXHIBITS, FINANCIAL STATEMENT
SCHEDULES



(a) Documents filed as part of this report.



1. Financial Statements. Consolidated Financial Statements are included
in our Original 10-K immediately following the signature page of the report.



2. Financial Statement Schedules.



All schedules were omitted because they were not applicable or the
required information was shown in the Consolidated Financial Statements or notes thereto filed with our Original 10-K.



3. Exhibits.



See note below under (b).



(b) Exhibits



The exhibits listed in Part IV, Item 15. “Exhibits, Financial
Statement Schedules” of the Original 10-K were filed or incorporated by reference as part of the Original 10-K and Exhibit
10.10 and Exhibit 10.15 listed in the Exhibit Index below are filed herewith as part of this Amendment No. 3 to replace Exhibit
10.10 and Exhibit 10.15 of the Original 10-K.



|Exhibit Number | Description of Document                                                                                
|-------------- | -------------------------------------------------------------------------------------------------------
|               |                                                                                                        
|10.10^*        | Option and License Agreement between the Company and CrystalGenomics, Inc. dated March 21, 2016.       
|10.15^*        | License Agreement dated as of March 6, 2018 between the Company and Ohm Oncology Inc.                  
|31.1*          | Certification of Principal Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
|31.2*          | Certification of Principal Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.





* Filed herewith.



^ Portions of this exhibit have been omitted pursuant to Rule 601(b)(10)
of Regulation S-K.















SIGNATURES





Pursuant to the requirements of the Securities Act, the Registrant
has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of San Diego,
State of California, on the 22nd day of April, 2019.







Aptose Biosciences Inc.





By: /s/ William G. Rice

William G. Rice

Chairman, Chief Executive Officer and President