WebMD Health News
Laura J. Martin, MD
April 21, 2010 -- An experimental oral drug is showing early promise for the
treatment of chronic hepatitis C virus (HCV) infection,
a study shows.
In preliminary research published this week in Nature, researchers
from Bristol-Myers Squibb -- the maker of the drug -- report that patients who
took the drug showed dramatic reductions in viral load while exhibiting few
The research is so early that the drug hasn't been named. It is known as
But the study provides the first clinical evidence that targeting the HCV
protein NS5A may be an effective strategy for curing patients who are
chronically infected with the HCV virus, says Nicholas A. Meanwell, PhD, who is
executive director of chemistry with Bristol-Myers Squibb.
Chronic HCV infection is a leading cause of liver cirrhosis, liver cancer, and liver failure and is the leading
reason for liver transplants in the U.S.
The current treatment for chronic HCV -- intravenously administered
peg-interferon and ribavirin -- cures about half of people with genotype 1 who
take it. But many patients find they cannot tolerate months of treatment with
interferon, which can cause anemia and severe flu-like
Cure rates are lower for people with HCV genotype 1, which includes about
70% of Americans chronically infected with hepatitis C virus; and they are
lower still for people who do not respond well to initial treatment.
"It is clear that other treatments are needed," Meanwell tells WebMD. "What
we are developing, and a lot of other companies too, are small molecule
antiviral agents that specifically target the virus."
In fact, no fewer than 90 studies are currently underway examining different
HCV-targeting drugs. Two of these drugs,
Vertex Pharmaceutical's telaprevir and Merck's boceprevir, are in the final
stages of study and may make it to the market as early as next year.
A unique thing about the NS5A-targeting drug, according to Meanwell, is that
laboratory studies show it to be effective against all HCV genotypes.
Meanwell says future HCV treatments will most likely involve a combination
of drugs that specifically target the virus, similar to the "cocktail" approach
now used to suppress HIV infection.
That's because treatment with just one of these drugs will most likely lead
to drug resistance before a cure is achieved, he says.
And it remains to be seen if these HCV-targeting drugs can clear the virus
for good without interferon, which works by stimulating the immune system,
Saint Louis University HCV specialist Bruce Bacon, MD, tells WebMD.
The topic has been the subject of much debate at medical conferences in
which hepatitis C treatment is
discussed, he adds.
"Some people believe you need the immunologic boost that you get with
interferon for a cure," he says. "Others argue that prolonged suppression of
the virus will stimulate innate immunity that will rid the body of the virus
It also remains to be seen if an NS5A-targeting drug will be part of the
treatment mix, he says.
The Bristol-Myers Squibb researchers are just beginning early phase II
studies of the drug.
He says it is encouraging that the drug appears to be effective against all
HCV genotypes in laboratory studies.
"We really don't learn if drugs are safe and effective until the phase II
trials are complete," he says. "If they are not safe or effective, they usually
don't make it out of phase II."
SOURCES:Gao, M. Nature, April 21, 2010; online edition.Nicholas A. Meanwell, PhD, department of discovery chemistry, Bristol-Myers
Squibb Research and Development, Wallingford, Conn.
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