March 7, 2006
A Food and Drug Administration advisory panel has begun debating whether the health benefits of the multiple sclerosis drug Tysabri outweigh the risk that some patients might contract a rare brain disorder.
At issue is whether the drugs manufacturers, Biogen Idec and Elan, can market the treatment, which tests have shown to be highly effective in treating MS.
In November 2004, FDA fast-tracked Tysabris approval for use in multiple sclerosis patients following promising results seen early in two clinical trials. But within months of the approval, some patients taking the drug had developed a rare infection - progressive multifocal leukoencephalopathy, or PML - and two patients had died.
Dr. Annette Langer-Gould, a clinical instructor in neurology, treated a patient who was part of the clinical trial and developed PML after taking Tysabri; the patient survived.
But that experience, coupled with an examination of Smith's case, prompted Langer-Gould to approach Dr. Lawrence Steinman about writing an article that would examine the appropriateness of testing a drug on people with no evidence of the disease and who are not disabled at the time of the trial.
"We are arguing that people with no disability should probably not enter into a clinical trial or be recruited into clinical trials, because where is the potential benefit to them if nothing is wrong?" said Steinman, professor of neurology and neurological sciences and of pediatrics.
"This situation represents a systemic problem," said Langer-Gould. "It is not just one company being a rogue, doing something out in left field."
The FDA withdrew Tysabri only three months after its approval. The FDA advisory panel is now meeting about the possibility of bringing back Tysabri as a single therapy.
"I predict it will come back with really hellacious warnings," said Steinman. "I think the right course would be to have it undergo more testing, but I don't think that is practical or fair to patients; they ought to have the opportunity to decide with their physicians if they are willing to take the one in a thousand risk of dying."
But Steinman and Langer-Gould expressed reservations about the drug returning to the market. They noted that its effects, while impressive, are in general not much better than what is seen with other available drugs: The risk of relapse dropped from an average of two relapses every three years using other approved multiple sclerosis drugs to one every three years with Tysabri.
"Do you want to expose someone to the risk of death for eliminating one relapse every three years?" said Steinman. "I say no."
