By Catherine Arnst Medical research on the heart has moved into a controversial realm -- possible correlations between a patient's race and the effectiveness of treatment. A wide range of diseases, including certain types of cancer, hypertension, and sickle-cell anemia seem to be more prevalent in certain races, but few efforts have been made to test new medications based on such ethnic differences.
The legitimacy of race-based therapeutics got a boost on Nov. 8, however, with the release of the first major study to test an experimental drug only in African Americans.n 18-month examination of1,050 African Americans suffering from heart failure found that those who took the experimental drug BiDil, made by NitroMed (NTMD) in Lexington, Mass., lived significantly longer than those on standard therapy.
Black Americans are more likely to suffer from heart failure than other races. They also develop cardiac problems earlier and are 2.5 times more likely to die from such diseases.
"A VERY CRUDE MARKER." The results of the African American Heart Failure Trial (A-HeFT), released at the American Heart Assn.'s Scientific Sessions in New Orleans on Nov. 8, found that the group of patients treated with BiDil in addition to standard therapy had 43% fewer deaths than the control group. The group also was hospitalized 33% fewer times and experienced early and sustained improvement in their quality of life. NitroMed filed with the Food & Drug Adnministration for approval of the drug on Nov. 1.
Medical researchers at the conference were quick to point out that BiDil might be just as effective in other ethnic groups. "Race is a very, very crude marker here," said Dr. Raymond J. Gibbons of the Mayo Clinic. And Dr. Salim Yusuf of McMaster University in Ontario, Canada, said the results may wellbe extrapolated to whites, Asians, and other races. Still, the study does support a growing interest in developing individual treatments for patients based on their genetic makeup.
A DEGENERATIVE DISEASE. The A-HeFt trial was predicated on an earlier finding: Many heart-failure medications are less effective in African Americans than in whites, suggesting that the disease may develop differently in different races, although no satisfying explanations have yet been proposed as to why this is so. An earlier BiDil trial in a much larger population showed no benefit,but when NitroMed reanalyzed the data it noticed a benefit in African Americans, and that led to the A-HeFT study.
Heart failure is a degenerative disease in which the heart stops pumping efficiently, causing the organ to enlarge and beat erratically. It affects about 5 million Americans, including about 750,000 African Americans. There is no cure, and about 50% of patients die within five years of diagnosis (see BW Online, 11/8/04, "Keeping Swollen Hearts in Shape").
Doctors believe the disease is caused in part when the body doesn't produce enough nitrous oxide, which plays an important role in regulating blood flow and heart health. BiDil is a combination of two drugs more than 20 years old, isosorbide dinitrate and hydralazine, that together enhance the production of nitrous oxide.
"A NEW ERA?" BiDil was so effective that the trial was halted 18 months earlier than planned so that all the patients involved could be switched over to the drug. The only side effects were headaches and dizziness, the researchers said.
The results were also published in the New England Journal of Medicine, with an accompanying editorial asking "Are we moving into a new era of race-based therapeutics?" The editorial, by Dr. Gregg Bloche of Georgetown University Law Center, acknowledged that the question is awkward, but he asserts that the medical Establishment shouldn't shy away from the potential benefits of race-conscious therapeutics.
In one sense, said Dr. Gibbons, the A-HeFT trial could just be the first step to a day when any therapeutic is prescribed based on the patient's genetic makeup, no matter what the race. Arnst is a senior writer for BusinessWeek