First 'black' drug nears approval
Helen Pearson
Controversial study suggests treatment should factor in the patient's ethnic
group.
The heart drug BiDil exceeded all expectations when tested in African
Americans.
A heart drug being tested in black patients is on course to become the first
medicine approved for use in a specific ethnic group, challenging those
scientists who believe that race is a bad basis for prescriptions.
The drug, made by Massachusetts-based pharmaceutical company NitroMed, was
abandoned after a trial in the 1980s produced unimpressive results. But,
because the data hinted at differences between white and black patients'
responses, in 2001 NitroMed decided to carry out a further clinical trial using
only African Americans.
This week NitroMed announced that the trial, in over 1,000 black heart-failure
patients, has been stopped early because it appears so effective when used on
top of normal therapy. "I'm so thrilled about it," says study leader Anne
Taylor of the University of Minnesota, Minneapolis. If the drug, called BiDil,
receives regulatory approval, the company says it will aim to launch it in
early 2005.
But BiDil revives controversy about whether, and how, race should be used to
prescribe medicines. In the clinic, for example, doctors will have to work out
who is classed as African American in a racially mixed population. "It really
becomes problematic," says Sandra Soo-Jin Lee, an anthropologist who studies
race in science at Stanford University, California.
Skin deep
Doctors have long known that different ethnic populations can have different
susceptibility to diseases or react differently to drugs. Drug labels for the
common heart drugs called ACE inhibitors note that they may be less effective
in black people.
BiDil contains two generic medicines that together boost production of nitric
oxide, a molecule that relaxes blood vessels and eases strain on the pumping
heart. Taylor believes that African Americans, who have a higher rate of heart
disease, react better because they tend to have lower levels of nitric oxide
than other ethnic groups.
I still think skin pigment is a lousy predictor of heart function
Howard McLeod
Fritz Haber Institute of the Max Planck Society, Berlin
Some scientists argue that race is a poor way of guessing a person's response
to a drug. "I still think skin pigment is a lousy predictor of heart function,"
says Howard McLeod of Washington University in St Louis, Missouri.
McLeod argues that it is better to identify the one or more genetic variations
that control whether the body reacts well to a drug and prescribe it to those
people, regardless of race. In the case of BiDil, for example, the genetic
difference responsible probably occurs more commonly in the African American
population. But the same genetic difference could exist, at a lower frequency,
in Caucasian, Asian or other ethnic groups.
Surrogate markers
The genetic argument was backed up by a study in 2001, in which British
researchers divided a population into four different groups based on 40 genetic
markers. They found that these groups were a better predictor of drug response
than ethnic ones1.
We hold the trump card: it works
Karsten Horn
Anne Taylor, University of Minnesota, Minneapolis
Taylor acknowledges these points and says that she plans to scan the genes of
those patients who responded to BiDil to find those that will foretell a
patient's response. Until these results are in, Taylor argues that race may
serve as a reasonable surrogate for making prescriptions, when used alongside a
patient's medical history. "We hold the trump card: it works," she says.
Future tests could show that other ethnic groups respond to the drug when it is
given, as in the current trial, alongside conventional treatment. But Taylor is
urging the traditionally white-dominated clinical trials to incorporate
patients from all ethnicities now, so that differences in their responses can
be picked up from the start.
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