Adding an experimental drug to standard treatment more than doubles the likelihood of knocking out hepatitis C in patients with the chronic liver infection, two studies in the March 31 New England Journal of Medicine show.
The new drug, boceprevir, and a similar drug called telaprevir (SN: 5/23/09, p. 12) have now shown the ability to wipe out the virus in many patients. Both drugs are currently under review by the Food and Drug Administration, and scientists feel that both are destined for approval.
“This is the first time I can remember being so optimistic about this really difficult virus,” says Donald Jensen, a hepatologist at the University of Chicago School of Medicine who wasn’t involved in the new studies. Hepatitis C can lead to liver cirrhosis and cancer.
Both new boceprevir trials started with hundreds of hepatitis C patients receiving a four-week course of the current standard medication, a one-two punch of drugs called peginterferon alfa-2b and ribavirin. The patients were then randomly assigned to get boceprevir or a placebo added to this regimen, without knowing which they were getting.
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After receiving treatment for up to 44 weeks, those getting boceprevir were two to three times more likely to knock the virus down to undetectable levels in the blood as were those getting only the standard dual-drug therapy, researchers report.
The two trial groups weren’t identical: One recruited previously treated hepatitis C patients, while the other enlisted only patients who hadn’t yet been treated. But both studies showed viral clearance rates of nearly two-thirds among those getting the triple therapy, compared with only 21 to 38 percent success among those getting the standard regimen.
A patient who clears the virus is often cured, says Fred Poordad, a hepatologist at Cedars-Sinai Medical Center in Los Angeles, who coauthored both studies. He cites 10 years of follow-up data from people who had cleared the virus after getting the standard peginterferon/ribavirin treatment. If the virus doesn’t reappear within six months after treatment, he says, close to 100 percent of them remain free of virus for good.
But 25 to 30 percent of those receiving standard treatment typically experience such a relapse shortly after treatment. With boceprevir added to the mix, that figure can be expected to fall below 10 percent, Poordad says.
The results thus indicate that 60 to 70 percent of patients getting the triple therapy “are now cured,” says Bruce Bacon, a hepatologist at Saint Louis University School of Medicine who coauthored both of the new studies.
The treatment does carry side effects. In both trials, nearly half of patients getting boceprevir developed anemia, compared with 20 to 29 percent of those on the standard dual treatment. Anemia is treatable, Bacon says. Nearly all patients in both trials reported some other side effects — including fatigue, headache and nausea — while taking the drug regimen. Bacon acknowledges these adverse effects, but adds that most hepatitis C patients “are willing to tough it out.”
Black patients didn’t benefit as much from the treatment as did other racial groups because some blacks carry a genetic variant that limits the effect of the drugs, Jensen says. Even so, roughly half of blacks getting the triple treatment saw their virus fall below detectable levels, a substantially better rate than those on dual therapy.
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Merck makes boceprevir and sponsored these two trials. Vertex Pharmaceuticals makes telaprevir. Bacon notes that these studies now show that the effectiveness of boceprevir and telaprevir are similar. That’s not surprising since both drugs inhibit protease enzymes. While protease enzymes play vital roles in the body, thwarting specific proteases can stall virus replication.
The drugs work only on genotype 1 hepatitis C, but that form accounts for about three-fourths of all hepatitis C in the United States.