Oct. 14, 2010 -- The long wait for new drugs that cure hepatitis C virus (HCV) may soon be over.
In early research, a combination of two experimental, oral, direct-acting antiviral drugs dramatically reduced levels of the virus in the blood of infected patients over two weeks of treatment.
And studies of other experimental drugs that also directly target HCV are under way.
For decades, injected interferon and oral ribavirin have been the only treatment options available, but only a small fraction of patients have access to the drugs. And many patients who start them soon stop due to side effects.
Today’s standard HCV treatment -- combination pegylated interferon and ribavirin -- cures about half of patients with genotype 1 HCV. Genotype 1 is the most common HCV type in the U.S. and the hardest one to treat.
“We are on the eve of a new era in hepatitis C virus (HCV) treatment,” HCV expert David L. Thomas, MD, of Johns Hopkins School of Medicine writes in an editorial appearing in the Oct. 15 issue of TheLancet.
He adds that in the foreseeable future, “nearly all those who are treated might be cured.”
Avoiding Drug Resistance
Researchers say the newly published study represents a “proof of concept” that the combined oral direct-acting antiviral therapy similar to that now used to manage HIV can dramatically lower virus levels. But longer studies are needed to determine if the approach can cure patients by completely eradicating the virus.
Direct-acting antiviral drugs work by blocking viral replication. When the drugs are given as single agents, patients typically become resistant to them, often within as little as two to four weeks, study researcher Edward J. Gane, MD, tells WebMD.
“The point of this approach was to use a combination of direct-acting agents that have different mechanisms of action to avoid resistance,” he says.
The study included 88 patients with chronic HCV infection living in New Zealand and Australia, treated for up to 13 days with various doses of a combination of the experimental antiviral drugs RG7128 and danoprevir or placebo.
All the patients had genotype 1 infections. Some had been treated unsuccessfully with interferon and others had never been treated before.
Over the course of treatment, HCV levels in the blood of some patients who took the experimental drugs dropped so low that they were undetectable.
Few treatment-related side effects were reported, even at higher doses. And none of the patients developed drug resistance.
New Treatments Coming
Perhaps most significantly, patients who had been treated unsuccessfully with interferon responded almost as well as those who had never been treated.
“Right now we really have nothing to offer patients who have failed interferon,” Gane says. “This would be a big step forward.”
The researchers estimate that the total treatment time to eradicate HCV infection would be about 8 to 12 weeks -- about one-fourth the length of a standard course of interferon treatment.
They hope to confirm this in future studies and to determine if adding ribavirin to the treatment regimen improves outcomes.
Thomas says it remains to be seen whether this combination or another combination of direct antiviral drugs will prove most effective.
“But there will be interferon-free treatment of hepatitis C. It is just a matter of time,” he tells WebMD. “This is the first study to be published that moves us in that direction, but it won’t be the last.”