Aptevo Therapeutics Inc. is a clinical-stage biotechnology company focused on developing novel bispecific and trispecific immunotherapies for cancer treatment. Its lead candidate, mipletamig (CD123 x CD3), is a T-cell engager evaluated in the Phase 1b/2 RAINIER trial for frontline acute myeloid leukemia, combined with standard therapies, showing promising remission rates and a favorable safety profile without cytokine release syndrome in frontline patients. The pipeline includes eight candidates, such as ALG.APV-527 targeting co-stimulatory receptors and tumor antigens, APVO442 (PSMA x CD3) for prostate cancer, APVO455 (Nectin-4 x CD3) for solid tumors, and trispecifics APVO451 and APVO452 that engage tumor antigens, CD3 for T-cell activation, and CD40 for immune modulation. These are generated using the proprietary ADAPTIR and ADAPTIR-FLEX modular protein technology platforms, designed to enhance immune responses against hematologic malignancies and solid tumors. Founded in 2016 and headquartered in Seattle, Washington, Aptevo Therapeutics Inc. operates in the immuno-oncology and hematology sectors, advancing next-generation T-cell engagers to address unmet needs in cancer care.