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Researcher cites "bias" toward Peg-Intron in trial
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By Ransdell Pierson
NEW YORK, Jan 7 (Reuters) - A lead researcher for a high-stakes trial comparing the world's top-selling drugs for hepatitis C said the study's design could "bias" results in favor of Schering-Plough Corp.'s product.
"Unfortunately life is not perfect and this study is not perfect as well," Dr. John McHutchison, co-lead investigator of the Schering-Plough (SGP.N: Quote, Profile, Research) trial, told Reuters in an interview on Thursday.
Schering-Plough's Peg-Intron and Roche Holding AG's (ROG.VX: Quote, Profile, Research) more popular rival medicine, Pegasys, are both injectable forms of interferon. They are used in 48-week treatments with a pill called ribavirin that helps them eradicate the hepatitis C virus, the biggest cause of liver transplants.
McHutchison, a Duke University researcher, said the study's design will probably allow more patients receiving Peg-Intron to stay on stronger doses of ribavirin than those taking Pegasys.
"Maintaining the (highest tolerable) dose of ribavirin, regardless of which interferon is used, is very important for controlling the virus, particularly in the early part of treatment," McHutchison said.
Schering-Plough in May launched the 2,880-patient U.S. trial, called IDEAL, and hopes to unveil results in 2007 that will prove Peg-Intron is superior.
Should it triumph, Schering-Plough aims to use the data as a marketing weapon to stem lagging sales of its one-time blockbuster, and help the struggling drugmaker regain earnings growth.
Peg-Intron and Schering-Plough's brand of ribavirin had combined third-quarter sales of $184 million, a fraction of the $703 million they boasted in the same quarter of 2002.
McHutchison said Peg-Intron patients will take starting ribavirin doses of 800 milligrams to 1400 milligrams daily, vs 1,000 to 1,200 milligrams for Pegasys patients.
But Peg-Intron patients who develop anemia or other side effects from ribavirin will have their daily dose of the pill reduced by 200 milligrams, with subsequent 200-milligram cuts if necessary.
By contrast, Pegasys patients with side effects must have their ribavirin cut back to 600 milligrams in one fell swoop.
"The dose reductions for ribavirin are not equivalent in the two arms of the study and could therefore introduce a potential bias" in favor of the Peg-Intron arm of the trial, McHutchison said.
McHutchison said he expressed his concerns to Schering-Plough, which in turn relayed them to the U.S. Food and Drug Administration before the trial began.
However, the FDA insisted that instructions on the Pegasys drug label be followed -- any ribavirin reductions must be to 600 milligrams.
"The FDA wouldn't allow it (smaller cutbacks), and unfortunately that's the way it stands," McHutchison said.
However, McHutchison said most doctors typically reduce ribavirin among Pegasys patients by 200 milligram increments.
Despite the potential ribavirin dose advantage to Peg-Intron patients, McHutchison and Schering-Plough said the study is large enough to demonstrate the true superiority of either medicine.
The new trial began two years after Roche launched Pegasys in the United States and ended Peg-Intron's monopoly for treating the often-fatal disease. An estimated 4 million Americans are believed to be infected by the virus.
Pegasys has leapfrogged Peg-Intron in sales largely due to its greater convenience. All patients receive the same injectable dose, whereas Peg-Intron is given according to body weight.
Pegasys and Roche's own brand of ribavirin command a 62 percent share of the U.S. market, according to Verispan LLC, which tracks drug sales for health-care companies.
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