Fri May 27, 2011
New drugs promise higher cure rates for hepatitis C
The new drugs should greatly improve cure rates for the more than three million Americans affected by this potentially fatal disease.
Hepatitis C is a bloodborne virus. Before 1992 when widespread blood screening began, some people got the disease through blood transfusions or organ transplants. Today, the most common cause of infection is sharing needles for injection drug use.
Liver disease specialist Dr. Bruce Bacon of Saint Louis University says it can take years, or even decades, for the virus to cause enough liver damage to produce symptoms.
“People got their hepatitis C in the '60s and '70s, and early '80s, and now are having all these problems from it 20 or 30 years later,” Bacon said.
About three-quarters of Americans with hepatitis C don’t know they have it.
Bacon says about 20 percent of people exposed to hepatitis C recover from the virus on their own, without treatment.
“The flip side of that is about 80 percent of people, 80, 85 percent of people, do get chronic hepatitis,” Bacon explained. “And of those patients, 20 to 30 percent of people develop cirrhosis, and of those, two to three percent of patients develop liver cancer."
Worldwide, there are six different strains, or genotypes, of hepatitis C. Saint Louis University researcher Dr. Adrian Di Bisceglie says that in the U.S., about 70 percent of patients have the genotype 1 form of the virus.
“And it turns out that genotype 1 is the most hard to treat,” Di Besceglie said.
For the past decade, treatment has meant a year-long regimen of two drugs: an immune system booster called pegylated interferon, and an antiviral medication known as ribavirin.
Di Besceglie says that two-drug treatment often hasn’t worked for patients with the genotype 1 form of the virus. “In that genotype, only about 40 percent of patients get cured when they’re treated with interferon and ribavirin,” Di Besceglie said.
In a clinical trial funded by the drug maker Vertex, Di Besceglie helped test how hard-to-treat genotype 1 patients responded when a new Vertex drug, telaprevir (Incivek™), was added to the current two-drug treatment.
“The cure rates or the rates of sustained virologic response go from the 40 percent number that I mentioned in patients with genotype 1, to 75 percent,” Di Besceglie said.
Dr. Bacon led a clinical trial for a similar medication, boceprevir (Victrelis™), funded by that drug’s developer, Merck. Bacon says adding boceprevir to the standard two-drug treatment significantly improved cure rates, even for patients who had been treated before and failed to recover.
“In the treatment experienced patients, those who hadn’t responded or who had relapsed previously, the numbers are more like 20 percent with the standard therapy being retreated, versus about 60 to 65 percent cure rate with the addition of boceprevir,” Bacon said.
Dr. Barbara McGovern treats patients with hepatitis C at the Lemuel Shattuck Hospital in Boston. She was on an independent panel of experts that reviewed data on both drugs for the FDA. “The difference between what you can do with dual therapy and triple therapy is like night and day,” McGovern said.
She says the new drugs do have some side effects – boceprevir can cause anemia, and telaprevir a severe rash – but she believes their benefits outweigh their risks. “We always have to measure risks and benefits, but the amount of patients who are cured – and that’s a very special word in infectious diseases – is so much higher,” McGovern said.
The current two-drug treatment costs on the order of $20,000. Adding the new drugs will likely double or triple that. But Dr. Adrian Di Besceglie says it’s worth it. “You save downstream by saving the costs of caring for patients with decompensated cirrhosis, liver cancer, liver transplantation, all of that,” Di Besceglie said. “The last few months of life when you have liver failure is terribly, terribly expensive.”
Di Besceglie, Bacon, and McGovern all say there are even better drugs in the pipeline, but those won’t get FDA approval for at least three to five years. Boceprevir and telaprevir are already on their way to pharmacies.