X0306 4 2022-09-19 0 0000882361 Aptose Biosciences Inc. APTO 0001650476 Payne Fletcher C/O APTOSE BIOSCIENCES INC. 251 CONSUMERS ROAD, SUITE 1105 TORONTO A6 M2J 4R3 ONTARIO, CANADA 0 1 0 0 SR VP & Chief Fin. Officer Common Shares 2022-09-19 4 P 0 10000 0.6775 A 10000 I Fletcher Payne 2019 Trust Exhibit 24.2 Power of Attorney /s/ Leslie Auld as attorney-in-fact for Fletcher Payne 2022-09-21