Experimental Hepatitis C Drug 'Promising'
Early Findings Show Good Response in Hard-to-Treat Patients
Oct. 27, 2003 -- Roughly half of all patients infected with hepatitis C virus can be cured. And now, an experimental drug is showing promise for the other half who don't respond to first-line hepatitis C drugs.
A California-based pharmaceutical company hopes its experimental drug will become the first hepatitis C drug to win approval for treatment of people who don't respond to initial treatment.
In a study sponsored by manufacturer SciClone Pharmaceuticals, 61% of people who had not responded to initial treatment improved with the experimental hepatitis C drug Zadaxin when combined with standard first-line hepatitis C drugs pegylated interferon and ribavirin.
The interim report on the ongoing pilot study involved just 23 patients treated for just 12 weeks, but a company spokesman calls the findings promising. The findings were reported at the annual meeting of the American Association for the Study of Liver Diseases (AASLD) in Boston.
At week 12, 10 of 16 study participants showed evidence that the amount of hepatitis C virus in their blood was falling -- called a virologic response. And nine of the 16 had a normal liver enzyme test.
"The fact that we have seen these early responses is certainly no guarantee that we will see sustained responses in these patients," SciClone vice president for medical affairs Eduardo Martins, MD, PhD, tells WebMD.
But he adds that previous research has suggested that when things look good early on, they are more likely to continue on that path. "We know that early virologic responses are very indicative of sustained responses in previously untreated patients."
More Ongoing Research
The company hopes to enroll 50 people in the ongoing trial of the three hepatitis C drugs. It is also conducting larger phase III trials of Zadaxin and pegylated interferon without ribavirin in patients who failed to respond to prior treatment. Patients in all of the studies will be treated for one year and will be observed for six months after that.
Hepatitis C treatment expert Howard J. Worman, MD, called the findings on the triple hepatitis C drug regimen "extremely preliminary," and he questioned the relevance of using early virologic response as a marker of success in this group of patients.
Virologic response has been shown to be an accurate predictor of sustained response or cure in previously untreated patients. But it is not known if the same is true for patients who have failed previous treatment with hepatitis C drugs.
Worman says that one must wait at least 24 weeks after completing a course of treatment with hepatitis C drugs to determine if these patients have achieved sustained responses. Worman is an associate professor of medicine at Columbia University and author of The Hepatitis C Source Book.
3 Drugs vs. 2
Martins says it is too soon to tell if the triple hepatitis C drug combination that includes ribavirin is more effective than the two-drug Zadaxin plus interferon regimen being evaluated in the phase III trials. The company says it expects to report findings from these trials sometime in 2005 and hopes to win FDA approval for the drug within the next year.
"As new infections continue to drop and first-line treatments cure more patients, treating these non-responding patients will be a bigger and bigger part of what we do," Martins says.