March 30, 2011 -- Two highly anticipated hepatitis C drugs are poised to usher in a new era in the treatment of the viral disease as early as this summer, experts say.
The Merck drug boceprevir and Vertex Pharmaceutical’s similar drug telaprevir are expected to win FDA approval within months, following phase III trials showing that both drugs boosted cure rates to around 70% when used with standard therapy.
The drugs will be used in patients with HCV genotype 1 -- the hardest to treat form of the viral infection.
Adding one of the drugs to the current two-drug regimen of peginterferon and ribavirin will make the treatment of hepatitis C more complex, but it will also cure a lot more people, hepatitis C specialist Donald M. Jensen, MD, of the University of Chicago Medical Center, tells WebMD.
“Triple-drug therapy represents a major advance in the treatment of hepatitis C for patients,” he says.
Results from two phase III boceprevir trials are published in the New England Journal of Medicine.
Combining Drug Treatments
In one trial, 66% of previously untreated patients treated with the three-drug regimen of boceprevir, peginterferon, and ribavirin cleared the virus for good, compared to 38% of patients treated with peginterferon and ribavirin alone.
Patients who show no evidence of hepatitis C virus (HCV) infection in the blood for six months are considered cured because the likelihood that the virus will reappear is very small. This is known medically as sustained viral clearance.
In another study, just over half of patients who did not respond to the initial two-drug treatment achieved sustained viral clearance when boceprevir was added to a second, 44-week course of treatment. Only 7% of patients treated for a second time with standard therapy cleared the virus for good.
Responses to the triple-drug therapy were even better in patients who initially responded to standard treatment but then relapsed. Seventy-five percent of these patients treated for 44 weeks achieved sustained viral clearances, compared to 29% of patients who got a second round of peginterferon and ribavirin.
The outcomes were similar to those seen in phase III trials of telaprevir.
“Triple therapy is coming soon,” veteran HCV researcher Bruce R. Bacon, MD, of St. Louis University School of Medicine, tells WebMD. “The only question is will it be triple-drug therapy with boceprevir or triple drug therapy with telaprevir?”
How the Drug Combo Works
About 3 million Americans are infected with HCV, and the CDC says more than 12,000 people in the U.S. die each year of liver disease and liver cancer caused by the virus. It is also the leading cause of liver transplants.
Most people show no symptoms of infection with hepatitis C for years, or even decades. Because of this, few people even know they are infected until they develop liver disease or have significant liver scarring, known as cirrhosis.
The two new drugs directly attack and suppress the virus by inhibiting the HCV protease enzyme, in a similar way that other protease inhibitors inhibit the HIV virus.
Because viruses quickly develop resistance to these drugs when given alone, they typically are not used alone.
That is why the three-drug cocktail will be needed, even though patients often find the flu-like symptoms and other side effects associated with peginterferon difficult to tolerate.
The two new drugs have proven to have a common side effect of their own: anemia.
In the newly published boceprevir studies, more than 40% of patients required the costly drug erythropoietin to boost red blood cell production.
“This is a very expensive drug, and I would imagine some insurance companies would not pay for it,” Hensen says. He says it remains to be seen if patients will stay on the three-drug regimen if they don’t have access to erythropoietin.
Experimental Drugs on the Horizon
The Holy Grail of HCV treatment is oral medications that clear the virus without major side effects.
Hensen says early trials of several candidates appear promising and treatment without peginterferon may be a reality within two or three years.
Bacon says the time frame may be closer to five or even 10 years.
An FDA advisory committee is scheduled to meet April 27 to consider recommending approval of boceprevir. The panel will consider Vertex’s application for telaprevir the next day.
Merck spokesman Robert Consalvo says the company hopes to have boceprevir on the market by this summer.
“We are working actively to prepare for the launch of this drug, and will do so very quickly once it is approved by FDA,” he tells WebMD.