The U.S. Food and Drug Administration has granted orphan-drug designation to Aptevo Therapeutics Inc.'s antibody treatment for acute myelogenous leukemia, or AML, a cancer of the blood and bone marrow.

The treatment, APVO436, works by binding to two cell receptors in the immune system, CD123 and CD3, to aid the body in detecting and fighting cancerous cells.

The treatment is being tested in a phase 1/1b clinical trial to test its effectiveness in fighting a group of cancers of the bone marrow, including AML, a rapidly progressing cancer originating from the production of dysfunctional blood cells in the body.

The orphan-drug designation encourages companies to develop cures for rare diseases by offering tax reductions, fee exemptions and a license to be the sole sellers of approved treatments for 7 years.

On Oct. 4, the company discontinued APVO210, its experimental drug for autoimmune diseases, after it failed to meet the desired product profile for commercialization in an early-stage study.