POWER OF ATTORNEY
Know all by these presents, that the undersigned hereby constitutes and appoints Leslie Auld
and Fletcher Payne, each acting alone, as the undersigned's true and lawful attorney-in-fact
to:
(1)	execute for and on behalf of the undersigned, in the undersigned's capacity as an
officer, director and/or 10% shareholder of Aptose Biosciences Inc. (the "Company"), Forms 3, 4
and 5 (including amendments thereto) in accordance with Section 16(a) of the Securities Exchange
Act of 1934 and the rules and regulations thereunder and any Form ID, Uniform Application for
Access Codes to File on Edgar, or Update Passphrase Form;
(2)	do and perform any and all acts for and on behalf of the undersigned which may be
necessary or desirable to complete and execute any such Forms 3, 4 or 5, Form ID or Update
Passphrase Form and timely file such forms (including amendments thereto) and application
with the United States Securities and Exchange Commission and any stock exchange or similar
authority; and
(3) 	take any other action of any type whatsoever in connection with the foregoing which,
in the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or
legally required by, the undersigned, it being understood that the documents executed by such
attorney-in-fact on behalf of the undersigned pursuant to this Power of Attorney shall be in
such form and shall contain such terms and conditions as such attorney-in-fact may approve in
such attorney-in-fact's discretion.
The undersigned hereby grants to each such attorney-in-fact full power and authority to do and
perform any and every act and thing whatsoever requisite, necessary or proper to be done in
the exercise of any of the rights and powers herein granted, as fully to all intents and
purposes as the undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact,
or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done
by virtue of this power of attorney and the rights and powers herein granted. The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request
of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange Act of 1934.
The undersigned agrees that each such attorney-in-fact herein may rely entirely on information
furnished orally or in writing by the undersigned to such attorney-in-fact. The undersigned
also agrees to indemnify and hold harmless the Company and each such attorney-in-fact against
any losses, claims, damages or liabilities (or actions in these respects) that arise out of
or are based upon any untrue statements or omission of necessary facts in the information
provided by the undersigned to such attorney-in fact for purposes of executing, acknowledging,
delivering or filing Forms 3, 4 or 5 (including amendments thereto), Form ID or Update
Passphrase Form and agrees to reimburse the Company and such attorney-in-fact for any legal
or other expenses reasonably incurred in connection with investigating or defending against
any such loss, claim, damage, liability or action.
This Power of Attorney supersedes any power of attorney previously executed by the undersigned
regarding the purposes outlined in the first paragraph hereof ("Prior Powers of Attorney"),
and the authority of the attorneys-in-fact named in any Prior Powers of Attorney is hereby
revoked.
This Power of Attorney shall remain in full force and effect until the undersigned is no
longer required to file Forms 3, 4 or 5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, unless earlier (a) revoked by the
undersigned in a signed writing delivered to the foregoing attorneys-in-fact or (b) superseded
by a new power of attorney regarding the purposes outlined in the first paragraph hereof
dated as of a later date.
IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed
as of this 20th day of September, 2022.

/s/ William G. Rice