A drug currently used to treat cancer is showing promise for treating sickle cell anemia that is resistant to standard treatment, according to the results of a study appearing in the journal Blood.
    Sickle cell anemia is caused by a mutation in the gene for hemoglobin, a substance that allows red blood cells to deliver oxygen to tissues throughout the body. As a result, red blood cells contain a defective form of hemoglobin (called hemoglobin S) and are prone to assuming a sickle shape. This shape in turn causes the cells to stick in small capillaries and block blood flow to tissues; it also causes the cells to be destroyed prematurely, leading to anemia.

    Researchers at the University of Illinois at Chicago and the Veterans Administration, Chicago West Side Division, treated seven adults with sickle cell anemia with the anticancer drug decitabine for 9 months. Five of the individuals had previously had no response to the drug hydroxyurea (Hydrea, Droxia), a standard treatment for the disease.
    Treatment lead to a nearly 5-fold increase in red blood cell levels of hemoglobin F, a form of hemoglobin that reduces sickling. At the end of the study, hemoglobin F comprised about 20% of all hemoglobin. Although the researchers did not study rates of complications of sickle cell anemia, this percentage of hemoglobin F is expected to have substantial benefits in individuals with this disease.
    One possible side effect of decitabine is a decrease in the number of infection-fighting white blood cells. However, by adjusting the drug dose according to each individual’s response and blood test results, the researchers were able to find a dose of decitabine that increased hemoglobin F levels without causing a substantial decrease in the number of these cells.