Pegging the interferon data

Schering-Plough Corp. (SGP, Madison, N.J.) has its PEG-Intron peginterferon alfa-2b under regulatory review in the U.S. and Europe to treat hepatitis C, while Hoffmann-La Roche Inc. (Nutley, N.J.) has its Pegasys peginterferon alfa-2a in Phase III testing. While the absolute numbers for virologic response in the Phase III data suggest that Pegasys may have greater efficacy, PEG-Intron, which uses polyethylene glycol (PEG) technology licensed from Enzon Inc., may enjoy a more meaningful advantage by reaching the market first (see Online Links, A7).

In Phase III testing, both Pegasys and PEG-Intron were superior to interferon alone (see "Pegylated interferon data").At first glance, Pegasys showed a 39 percent sustained virologic response at 72 weeks compared to PEG-Intron's 25 percent. However, there was a difference in the response of the conventional interferon groups as well - 12 percent in the PEG-Intron trial versus 19 percent in the Pegasys study...