There is encouraging news for people with hepatitis C virus (HCV). A new form of interferon-alfa, known as peg-interferon (PEG-Intron, from Schering Plough), shows better activity than the current version of the drug. This new version is bound to a chemical (called polyethylene glycol), which makes the drug active in the blood for longer periods than standard interferon-alfa. The article "New Information on Opportunistic Infections and Co-Infections" in PI Perspective 29 reported on early results of a different peg-interferon (Pegasys) that also showed improved activity over existing therapy.

PEG-Intron was compared to standard interferon-alfa in 1,219 people with HCV and abnormal liver enzymes (an indicator of liver injury). This study did not involve people co-infected with HIV and HCV. People took the drug for 48 weeks followed by a 24-week follow-up period in which they took no therapy. They either used 0.5mcg/kg, 1mcg/kg or 1.5mcg/kg of peg-interferon or three million international units of interferon-alfa. Both formulas require injections under the skin.

Almost 70% of the participants had genotype 1 HCV (the most difficult type to treat), and about 75% had HCV levels of over 2 million copies. Results after 48 and 72 weeks are in the table below.

People taking the 1.0 and 1.5mcg/kg doses of peg-interferon experienced a slightly greater number of side effects than those on the other two doses. The most common side effects included headaches, fatigue, flu-like symptoms, depression, and decreases in white blood cell counts, platelets (cells needed for blood-clotting) and neutrophils (a type of white blood cell that helps control bacterial and other infections).

Although its success rate is superior to the current interferon-alfa, PEG-Intron is still not overly impressive compared to standard HCV therapy, which is a combination of interferon plus ribavirin (Rebetol). It's likely peg-interferon will still have to be combined with ribavirin or other new anti-HCV therapies in development to get optimum results. Ongoing studies are now using peg-interferon with ribavirin to determine whether this will be more effective than peg-interferon alone.

PEG-Intron is likely to be approved by the Food and Drug Administration in spring 2001 and should be available by prescription shortly thereafter. However, an expanded access program for Pegasys is expected during the fall 2000.

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