APTOSE BIOSCIENCES INC. Table of Contents As filed with the Securities and Exchange Commission on December 29, 2023 Registration No. 333-275870 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 AMENDMENT NO.2 To FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 Aptose Biosciences U.S. Inc. Unit 120, 12770 High Bluff Drive San Diego, California 92130 (858) 926-2730 (Name, address, including zip code, and telephone number, including area code, of agent for service) COPIES ...