Population genomics is making rapid and remarkable advances in detailing the specific genetic variations that characterize people in different parts of the world. This information could provide, among other things, invaluable clues to why some medicines are more effective for particular ethnic groups. The worry is that genomic differences between groups will be misunderstood, and perhaps misused, to justify crude generalizations about races.
BiDil, a new heart failure drug that will be marketed to African Americans, doesn’t help. By most estimates, it is an important medicine for heart failure, a disease that has reached epidemic levels in the United States. A clinical trial completed last year found that the pill reduced mortality among African Americans with heart failure by an astounding 43 percent. That’s great news for patients and cardiologists. And the drug has gained the backing of prominent medical groups such as the Association of Black Cardiologists. But if the U.S. Food and Drug Administration approves a race-specific pill, which it could do by mid-year, it will send a confusing message about what researchers are learning from population genomics—and raise troubling questions about how drug developers and physicians will use their growing knowledge of group differences.
As our feature “Race and Medicine” (p. 60) explains, much of the controversy is over the validity of using race as a shortcut to more biologically exact categories. Critics of BiDil point out that conventional racial groups are socially constructed categories that may have little relationship to genetic populations. Such categories are an uncertain guide to predicting which patients a drug will benefit, and using them as such ignores the complex lessons of population genomics. While tests done in the 1980s and early 1990s suggested that the treatment that would later become BiDil was, on average, more effective for black patients than it was for whites, the pill has not been tested in a large study of an ethnically diverse population taking current heart failure medicines. This matters because the reason for the racial differences in the earlier studies is not known. Without that knowledge, it is not possible to specify more precisely which individual patients, black or white, the drug will actually help.
If the FDA determines that the medical evidence justifies BiDil’s approval, the agency must approve the marketing of the drug. But as David Goldstein, director of Duke University’s Center for Population Genomics and Pharmacogenetics, argues in our feature, the agency should also mandate additional research to determine why the drug is so beneficial for some patients. That type of research will take money and time, but it will be well worth it to learn how to prescribe the medicine effectively and safely. As Goldstein puts it, “Race is never a precise guide. If you don’t have other information, you might be prepared to use race as an interim measure, but you shouldn’t treat it as the end of the story.”
Health-care professionals, biomedical researchers, and drug developers need to address the health disparities among different groups in the United States. By shedding light on why some drugs are more effective for certain groups, population genomics can play a role in narrowing those disparities. But all parties involved should also make it clear to the general public that genetic variations among groups are not a matter of black and white. BiDil might be an effective drug, but marketing medicines on the basis of race should not be the wave of the future.