Aptevo Therapeutics Inc.

Item 8.01 Other Events. On October 26, 2026, Aptevo Therapeutics Inc. (the "Company") issued a press release announcing ten patients with newly diagnosed acute myeloid leukemia (AML) have advanced to allogeneic stem cell transplant following treatment with mipletamig in combination with venetoclax and azacitidine. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated by reference herein. Item 9.01 Financial Statements and Exhibits. (d) Exhibits The following exhibits are being filed herewith:

Press release of Aptevo Therapeutics Inc. dated October 26, 2026.

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