Of the millions of Americans infected with hepatitis C, only half respond to treatment. The others live with the constant threat that their health may suddenly, and fatally, deteriorate.
A new drug could improve those odds. When used with the antiviral drug interferon, a medication called Zadaxin may help thousands of patients better fight the disease.
"This medication looks promising for people who don't respond to other drugs," says Dr. Sammy Saab, a liver specialist at UCLA's David Geffen School of Medicine. "It may also be used as part of a combination drug cocktail for all hepatitis C sufferers, since it seems to work by a different mechanism of action than other medications."
About 4 million Americans are infected with hepatitis C, and about 2.7 million of those have an active infection, in which the liver is inflamed. Infection is insidious, however. People can be symptom-free for years, but the virus can quietly incubate, causing cirrhosis of the liver, liver cancer or even liver failure. Hepatitis C, which kills 10,000 people a year, is the leading reason for liver transplants in the U.S.
The current treatment -- a combination of two antiviral medications, interferon and Ribavirin -- helps only about half of those with active infections and less than a third who are infected with the more prevalent and more dangerous form of hepatitis C, known as genotype 1.
The drugs also have serious side effects, leading many people to stop taking them. Ribavirin can cause anemia, which leaves patients feeling extremely fatigued, while interferon can cause flu-like symptoms and birth defects if taken by pregnant women. These side effects "can result in having to reduce the dose and therefore decrease the efficacy of the drugs," says Dr. Adrian Di Bisceglie, a liver specialist at St. Louis University School of Medicine in Missouri.
Zadaxin has no apparent side effects. It is a synthetic version of thymosin alpha 1, a naturally occurring protein that circulates in the body and stimulates the production of certain immune system cells. Zadaxin is approved for sale in 30 countries as an antiviral drug to treat hepatitis B but in only a few countries to combat hepatitis C.
Results of a 2002 U.S. study of the drug as a hepatitis C therapy were encouraging. The test involved 31 patients who had high levels of genotype 1 and who hadn't responded to standard medications. Zadaxin, used in combination with interferon, greatly reduced levels of the virus in up to 36% of the patients.
