Aptevo Therapeutics is a clinical-stage biotech company developing cancer immunotherapies. Aptevo has no approved products and no product revenue; the company funds operations through capital raises and potential partnership deals. Aptevo's pipeline is built on two proprietary protein engineering platforms — ADAPTIR and ADAPTIR-FLEX — which it uses to design bispecific and trispecific antibody-based drugs that recruit the immune system to kill cancer cells. The modularity of these platforms lets Aptevo swap in different binding domains to generate new drug candidates without rebuilding the underlying protein scaffold. Aptevo has two clinical-stage candidates. Mipletamig is a bispecific antibody that links T cells to leukemia cells by binding CD3 and CD123 simultaneously, and is being evaluated in the RAINIER trial for frontline acute myeloid leukemia in older or less fit patients alongside venetoclax and azacitidine. ALG.APV-527 is a bispecific targeting 4-1BB and 5T4, designed to activate immune cells within the tumor microenvironment across a range of solid tumors; it is being co-developed with Alligator Bioscience. Beyond these two, Aptevo has six preclinical candidates, including two trispecifics. Aptevo's business model centers on advancing its pipeline to generate clinical data, then licensing or co-developing candidates with larger pharma or biotech companies. With only 33 employees, Aptevo outsources most clinical operations and manufacturing, keeping headcount costs low while R&D spending drives the cost structure.