Roche’s long-acting interferon alpha product Pegasys (peginterferon alfa-2a) is effective in the treatment of patients with hepatitis C who do not respond to a drug from its big rival Schering-Plough, according to preliminary results from a new study.

The study is a further boost to Roche’s product, which has been steadily winning market share from S-P’s Peg-Intron (peginterferon alfa-2b) since being introduced in 2001/2.

The combination of Pegasys and Roche’s antiviral drug Copegus (ribavirin) reduced circulating levels of the hepatitis C virus to undetectable levels in 47% of patients after 12 weeks’ treatment, all of whom had been unsuccessfully treated with Peg-Intron plus ribavirin. The large international trial - called REPEAT - also found that this response rate rose to 64% amongst patients who received a double induction dose (360mcg versus 180mcg) of Pegasys.

There are around 35,000-100,000 non-responders to therapy per year in the USA, a number predicted to grow to 1.4 million by 2014, according to market research company Datamonitor. This pool could exceed the number of new diagnoses by 2013, unless new therapeutic strategies are discovered [[30/09/05i]].

Pegasys and Peg-Intron between them share the bulk of an estimated $2 billion global market for HCV treatments, predicted to grow to around $4 billion in 2013. Five years ago, Peg-Intron dominated the market for long-acting interferon alpha products, with more than an 80% share, while Roche had yet to make any significant inroads, with less than 20%. Since then, Roche has captured more than 50% of the market, driving S-P’s product into a minority position.

The results were presented at the American Society for the Study of the Liver conference in San Francisco.

"These are very positive results for patients who have not responded to previous therapy," said Professor Patrick Marcellin of the Hopital Beaujon in France, one of the lead investigators of the study. "Previously these patients would have been considered difficult to treat; now there is hope for a cure."