When the drug telaprevir was added to standard treatment with peginterferon alfa and ribavirin, which are also antivirals, about half of patients who had failed previous treatment with the two drugs cleared the virus.
The patients showed no evidence of HCV infection six months after completing treatment, which is considered a cure.
Telaprevir is one of two highly anticipated drugs in the class known as protease inhibitors being studied in patients with chronic hepatitis C infection, a condition that affects about 3 million Americans and is the leading cause of liver transplants in the U.S.
Phase III trials are under way for telaprevir, manufactured by Vertex Pharmaceuticals, and boceprevir, manufactured by Schering-Plough.
Saint Louis University HCV specialist Bruce Bacon, MD, says when the two drugs make it to the market, which may be as early as next year, they will change the face of hepatitis C treatment.
Bacon did not participate in the new study, published in the April 8 issue of the New England Journal of Medicine.
“Triple drug therapy is coming and it will mean cures for many more people,” he tells WebMD. “My patients are very excited about it.”
Half of HCV Patients Cured
About 40% of previously untreated HCV patients are cured with the current treatment regimen, which includes 48 weeks of peginterferon and ribavirin.
A second round of treatment is often recommended for patients who fail to respond to initial treatment or who respond and then relapse. But this approach is not very effective.
In their latest study, Duke University researcher John G. McHutchison, MD, and colleagues achieved higher cure rates in previously treated patients than has been reported before by adding telaprevir to the other two drugs.
The study participants were randomly assigned to one of four treatment groups: 12 weeks of telaprevir and 24 weeks of interferon/ribavirin; 24 weeks of telaprevir and 48 weeks of interferon/ribavirin; 24 weeks of telaprevir and interferon without ribavirin; or 48 weeks of interferon/ribavirin without telaprevir.
The researchers report that:
- Just over half (52%) of telaprevir-treated patients were free of virus six months after therapy ended, compared to just 14% of those who did not take telaprevir.
- Patients who had responded to initial treatment, but later relapsed, did best on the three-drug regimen, with about three out of four achieving a cure the second time around.
- Slightly less than 40% of previous non-responders who got the triple therapy responded, compared to just 8% of those treated with standard therapy without telaprevir.
- Responses were better with the three-drug regimen than with peginterferon and telaprevir alone, suggesting that ribavirin is an important component of effective treatment.
- Responses were similar with 24 and 48 weeks of treatment in patients on the triple-drug regimen, but fewer side effects were reported with the shorter treatment.
More than three times as many patients in the telaprevir groups left the study because of troubling side effects. In all, 15% abandoned treatment compared to 4% of patients treated with peginterferon and ribavirin alone.
‘We had hoped adding (telaprevir) would not add to the side effect profile, but it is now clear there are more side effects with three drugs than two,” McHutchison tells WebMD. “I guess it’s true there is no free ride.”
Telaprevir’s manufacturer, Vertex Pharmaceuticals funded the study. McHutchison says he has received speaker and advisory fees from the company but has no other financial interest in the drug.
Shorter Treatment, Better Outcomes
In a study of previously untreated patients published last spring, McHutchison and colleagues reported better cure rates with half as much standard treatment when telaprevir was added.
A total of 41% of patients treated with 48 weeks of peginterferon and ribavirin achieved cures, compared to 61% of patients treated with 12 weeks of telaprevir and 24 weeks of peginterferon/ribavirin.
Bacon says slightly higher cure rates have been reported with the other investigational protease inhibitor boceprevir, but that these studies included 48 weeks of treatment.
“It may come down to patient preference,” he says. “Will patients give up a shorter treatment course for a higher cure rate? I know many of my patients would.”
Results from the phase III studies of telaprevir and boceprevir are expected later this year.