MS Drug Tysabri Linked to Third Case of Nervous System Disease
The manufacturers of multiple sclerosis (MS) drug Tysabri confirmed late March 30 that the drug has been linked to a third case of a deadly central nervous system disorder - news that analysts believe could close the door on the drug's potential return to the market.
Biogen Idec and Elan voluntarily suspended marketing and clinical use of Tysabri (natalizumab) Feb. 28, following reports that the drug was linked to two cases of progressive multifocal leukoencephalopathy (PML), a rare and frequently fatal, demyelinating disease of the central nervous system. The two initial cases involved MS patients taking Tysabri in combination with Avonex (interferon beta-1a), Biogen Idec's older MS treatment.
The companies' ongoing safety evaluation of Tysabri recently revealed a third case of PML in a patient taking the drug as part of an open-label Crohn's disease clinical trial. In July 2003, the case was reported by a clinical investigator as malignant astrocytoma, but further review of the case revealed that the patient contracted PML, the companies said in a joint statement. The patient died in December 2003.
Following the market withdrawal of Tysabri in February, Biogen officials said they hoped to return the drug to the market as soon as this fall, but some industry observers believe the latest PML case leaves the drug's future in serious jeopardy.