Drug shows promise in sickle cell anemia.

Drug shows promise in sickle cell anemia 

Early clinical studies suggest that a drug normally used to treat leukemia may be effective in treating sickle cell anemia, a genetic disorder in which patients produce defective hemoglobin, the oxygen-carrying molecule within red blood cells. Scientists pinpointed the mutation responsible for sickle cell anemia more than 20 years ago, but that finding has not led to an effective therapy. The recent development stems from researcher's observation that the mutation causes mild or no symptoms in people who naturally produce fetal hemoglobin -- a form normally produced only in the womb.

Hydroxyurea, the drug under study, has been used so far to treat about 60 patients with full-blown sickle cell anemia, according to study coauthor George J. Dover, a pediatrician at Johns Hopkins University School of Medicine. Among the 23 patients for whom the researchers have compiled complete data, the drug induced five to produce fetal hemoglobin at levels representing more than 20 percent of their total hemoglobin. In eight patients, fetal hemoglobin rose to a level of more than 10 percent. It represented less than 10 percent of total hemoglobin in five patients,, while another five showed no response. At about the 20 percent level, disease symptoms begin to lessen, Dover says. The researchers do not understand fully how the drug works, but it appears to activate a gene controlling fetal hemoglobin production, he says.

Now hydroxyurea is undergoing a multicenter, 38-patient trial to determine maximum dose levels and the magnitude of the fetal hemoglobin response. But researchers must show more than an increase in fetal hemoglobin, Dover says. They need to demonstrate that this treatment improves patients' lives, which are interrupted by frequent hosptital visits for painful episodes and infections resulting from blocked blood flow to vital organs. So far, it does not seem to produce any serious adverse effects, says Dover, who hopes to begin a controlled clinical trial of hydroxyurea in 1990.