As filed with the Securities and Exchange Commission on March 29, 2024. Registration No. 333-278103 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 AMENDMENT NO.1 TO FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 APTEVO THERAPEUTICS INC. (Exact Name of Registrant as Specified in Its Charter) (State or Other Jurisdiction of Incorporation or Organization) (Primary Standard Industrial Delaware 2834 81-1567056 (I.R.S. Employer Identification Number) 2401 4th Avenue, Sui ...