Aptevo Therapeutics Inc., a clinical-stage biotechnology company, engages in the discovery, development, commercialization, and sale of novel oncology and hematology therapeutics in the United States. Its marketed product includes IXINITY, a coagulation factor IX therapeutic indicated in adults and children 12 years of age and older with hemophilia B for control and prevention of bleeding episodes, and management of bleeding during operations. Its lead clinical candidate is APVO436, a bispecific immunotherapeutic protein that is in Phase 1/1b clinical trial for acute myeloid leukemia and high-grade myelodysplastic syndrome. The company's preclinical candidates include ALG.APV-527, a bispecific antibody to target 4-1BB x 5T4; APVO603, a dual agonist bispecific antibody to target 4-1BB and OX40; and other pre-clinical development stage therapeutics focused on immuno-oncology. The company has a collaboration and option agreement with Alligator Bioscience AB to develop ALG.APV-527. Aptevo Therapeutics Inc. was incorporated in 2016 and is headquartered in Seattle, Washington.