Pegasys Plus Ribavirin Appears Superior to Rebetron Combination Therapy
The combination of Pegasys (peginterferon alfa-2a) and ribavirin produces significantly increased sustained virologic responses compared to combination therapy with Rebetron, the current standard of care for treatment of chronic hepatitis C.
Michael Fried, MD, presented results of the study this week during a plenary session at Digestive Disease Week (DDW) 2001 (Atlanta, GA, May 20-23, 2001). "The combination of this drug plus ribavirin was clearly shown to be superior to our [current] standard of care, said Fried." Dr. Fried is associate professor of medicine and Director of Clinical Hepatology at the University of North Carolina Chapel Hill School of Medicine.
The study is the first large efficacy and safety study to directly compare Pegasys in combination with the antiviral drug ribavirin to Rebetron (interferon alfa-2b [Intron A] plus ribavirin) for the treatment of hepatitis C. Treatment with the pegylated interferons appear to offer significant advantages over "standard" interferon alfa. These include slowed clearance of the drug from the body and increased circulation time, which allows for once weekly dosing (by subcutaneous injection), compared to three times weekly injections with standard interferon (e.g., Intron A, Roferon A, Infergen). This study suggests that Pegasys (from Roche), like Peg Intron (from Schering) also offers more effective reduction of HCV viral load than the standard interferons.
Pegasys Trial Results
More than 1,100 treatment-naive patients were enrolled in one of three arms of the trial: (1) Pegasys (180mcg) plus ribavirin (1,000 or 1,200 mg), (n=453); (2) Rebetron (interferon alfa-2b 3 MIU and ribavirin 1000 or 1200 mg) (n=444); or (3) Pegasys (180 mcg) plus placebo (n=224). Patients were treated for 48 weeks and then monitored for an additional 24 weeks. Of the patients enrolled in the study, 65 percent were infected with genotype 1 (the most difficult genotype to treat), and 14 percent had cirrhosis (scarring of the liver.).
The study showed that 24 weeks after discontinuation of therapy, 56 percent of patients treated with Pegasys plus ribavirin exhibited a sustained virologic response (SVR) vs. 45 percent for Rebetron vs. 30 percent for Pegasys plus placebo. Sustained viral response is defined as undetectable serum HCV RNA (50 IU/ml) and normal liver enzymes six months after the end of treatment.
Among patients infected with genotype one, 46 percent had an SVR on Pegasys plus ribavirin vs. 37 percent of patients on Rebetron. An additional analysis suggests that 86 percent of patients treated with Pegasys plus ribavirin showed a viral response at 12 weeks and that 65 percent of this group went on to attain a SVR.
Adverse Side Effects
In addition to increased efficacy, the combination of Pegasys and Rebetol appeared to have fewer side effects than Rebetron. The investigators found that the most common side effects of interferon therapy, depression and flu-like symptoms, were significantly lower in the Pegasys arms. While 30% of the patients in the Rebetron arm experienced depression, of the patients in the Pegasys plus Rebetol and Pegasys plus placebo arms only 21% and 20%, respectively, experienced that complication.
The most common serious adverse events for Pegasys reported in clinical studies to date are psychiatric disorders, gastrointestinal disorders and infections; in addition, interferons have been associated with fatal or life-threatening neuropsychiatric, autoimmune, ischemic, and infectious disorders. The most common adverse events included flu-like symptoms, injection site reactions, partial alopecia, abdominal pain, depression, irritability, insomnia, dizziness and anorexia.
Severe psychiatric adverse events have occurred during combination interferon/ribavirin therapy, both in patients with and without a previous psychiatric disorder.
In addition, ribavirin has its own adverse events, the most serious of which are birth defects. For this reason, ribavirin and interferon/ribavirin must not be used by women, or male partners of women, who are or may become pregnant during therapy and during the 6 months after stopping therapy. In addition, ribavirin has been shown to cause anemia in some patients that may exacerbate pre-existing coronary heart disease or deteriorate cardiac function.
Reference M Fried and others. Pegylated (40 kDa) Interferon Alfa-2a
(PEGASYS®) in Combination With Ribavirin: Efficacy and Safety Results
From a Phase III, Randomized, Actively-Controlled, Multicenter Study.
Abstract 289. AASLD Presidential Plenary session.
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