A biotechnology company hopes to begin clinical trials next year on what it says will be a cheaper and more convenient way to provide the anemia drug erythropoietin, posing a potential challenge to Amgen and Johnson & Johnson.
The company, Ariad Pharmaceuticals, of Cambridge, Mass., said it planned to use gene therapy to provide patients with the gene responsible for producing erythropoietin, or EPO. Instead of constantly receiving injections of EPO, patients would be able to make their own.
EPO, a kidney-made protein that stimulates the body to produce oxygen-carrying red blood cells, is the best-selling product developed by the biotechnology industry. Combined sales by Amgen and its licensee, Johnson & Johnson, exceed $5 billion a year, which has made it a tempting target for potential competitors.
Currently the protein is given either by intravenous infusion or by injection, with up to three injections a week. For patients undergoing kidney dialysis, a major market, the cost is at least $7,000 to $9,000 a year.
At the meeting of the American Society of Nephrology in Philadelphia this weekend, Ariad and its collaborators at the University of Pennsylvania will report that 22 monkeys injected one time with the EPO gene were able to produce EPO for four years in some cases. Ariad uses a virus to carry the genes into muscles.
"All the moving parts now work really well long term, and the next stage is clinical and commercial," Ariad's chief executive, Harvey J. Berger, said.
With Ariad's system, the implanted genes do not switch on to make EPO until the patient takes a pill. That would allow patients to control how much EPO is produced and prevent harmful overproduction. Ariad said the pill would need to be taken once or twice a month.
Dr. F. John Gennari, a nephrologist at the University of Vermont, called the work intriguing because dialysis centers are always under pressure to cut the costs of EPO therapy. Dr. Steven J. Scheinman, chief of nephrology at SUNY Upstate Medical University in Syracuse, agreed, saying, "It might be nice to take a pill rather than get these injections."
Still, the clinical trials will take years and many challenges remain.
Gene therapy has a history of failure, even when scientists allow the implanted genes to be active all the time. Trying to switch genes on and off is even more difficult, and such switches tend to weaken over time. "You just better be sure your switch works," said John Monahan, chief executive of Avigen, another gene therapy company.
The therapy also carries safety risks, as highlighted by the 1999 death of teenager Jesse Gelsinger after he received gene therapy at the University of Pennsylvania, the same institution working with Ariad.
Questions might also be raised about the gene switch pill, a modified version of the drug rapamycin, which suppresses the immune system. Ariad maintains that its modified version is only minimally immunosuppressive. But dialysis patients who receive the gene therapy and then receive a kidney transplant would not be able to use rapamycin to fight organ rejection.
Amgen's patents are another potential obstacle. Amgen has already sued to stop one company, Transkaryotic Therapies, from selling EPO produced by another means. That case is on appeal.
Dr. Berger said Ariad's system infringes only Amgen's patent on the EPO gene, which expires in 2004 - well before Ariad's treatment would reach the market.
But a spokesman for Amgen disagreed, saying, "It would be certain that one or more other patents that expire much later" would be infringed.
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