Once an advisory panel voted unanimously to recommend that Tysabri, the controversial MS drug, be allowed back on the market, it was assumed that the FDA would follow that recommendation and approve BiogenÃ¢â‚¬â„¢s application immediately.Ã‚Â
Apparently, however, the agency intends to take some additional time before acting on the matter and, as a result, will not be making its decision until the end of June.
While the FDA usually follows the recommendations of its independent advisory panels, the contentious debate surrounding the re-marketing of this particular medication has prompted the agency to hold back on any final action until it is sure that a risk-management program designed to detect adverse reactions is adequate and ready to be implemented.Ã‚Â
The drug has been linked to the rare, but often fatal brain disorder known as progressive multifocal leukoencephalopathy (PML). Two deaths, and the possibility that more would occur, led to the drug being pulled from the market at the end of February 2005; only four months after it was released.
It is estimated by experts that PML remains a risk and will probably strike one in every 1,000 Tysabri users. The monitoring program and enhanced warnings are hoped to make that risk clear to MS patients who opt to take the drug and to detect any cases of PML in time to discontinue treatment and prevent any serious consequences or death.
While there is no assurance that any monitoring program can actually stop additional cases of PML or prevent additional fatalities once it is detected, the fact that the drug appears to work well, and the impassioned pleas from MS victims and their families to have it remain a treatment option, convinced the advisory panel that the risk/benefit analysis justifies the return of Tysabri to the market.