A hepatitis C virus (HCV) treatment regimen including Genentech’s Pegasys (pegylated interferon-alpha-2a) is superior to a regimen including Schering-Plough’s PEG-Intron (pegylated interferon-alpha-2b), according to two studies published in the January issue of Gastroenterology. The studies did not include people living with HIV, however.

New types of HCV treatment are on the horizon. However, the compounds furthest along in development must still be paired with the two existing drugs: pegylated interferon and ribavirin.

There has been some question as to which pegylated interferon, Pegasys and PEG-Intron, is superior in terms of treatment success. HCV treatment is deemed successful if a person achieves and sustains undetectable HCV levels for six months after completing a course of HCV treatment. This is called a sustained virological suppression, or an SVR.

To determine which pegylated interferon is more likely to achieve an SVR, two studies were conducted in people with HCV—people with HIV were not included in either study.

In the first study, Maria Grazia Rumi, MD, from the Università degli Studi di Milano, in Milan, and her colleagues compared the two treatments, combined with ribavirin in 219 people with HCV. In the second study, Antonio Ascione, MD, from the Center for Liver Disease at Fatebenefratelli Hospital, in Napoli, Italy, compared the two treatments in 320 people.

In both studies, people who received Pegasys were significantly more likely to achieve an SVR than people who received PEG-Intron—66 percent in the Pegasys group compared with 54 percent in the PEG-Intron group in Rumi’s study and 68.8 percent compared with 54.4 percent in Ascione’s study. Side effects were similar in both groups in both studies. The difference in efficacy was independent of the genotype, or strain, of HCV of the participants (for example, genotype 1, 2, 3 or 4).

In a special commentary appearing alongside the studies in Gastroenterology, Stefan Seuzem, MD, from Goethe University in Frankfurt concludes, “It took…eight years to characterize the…differences between the two drugs in detail. At the dawn of new direct antiretroviral drugs against the HCV we need now to investigate how important the observed differences between the peginterferons…are in combination with [the latest experimental drugs].”