Aptevo Therapeutics Inc., a clinical-stage biotechnology company, focuses on developing immunotherapeutic candidates for the treatment of various forms of cancer in the United States. Its lead clinical candidate is APVO436, a bispecific T-cell engaging antibody candidate that is in Phase 1b clinical trial for acute myelogenous leukemia and myelodysplastic syndrome. The company's preclinical candidates also include ALG.APV-527, an investigational bispecific ADAPTIR candidate that features a mechanism of action to target 4-1BB (CD137) and 5T4, a tumor antigen expressed in various types of cancers; and APVO603, a dual agonist bispecific antibody to target 4-1BB and OX40. It also develoes APVO442, a bispecific candidate based on the ADAPTIR-FLEX platform technology to enhance biodistribution of drugs to PSMA positive tumors for treatment of prostate cancer. 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.