Biogen Idec and Elan said they are taking "preliminary steps" to resume clinical trials of Tysabri. In a statement issued yesterday, both companies announced that findings from their safety evaluation of Tysabri in patients with multiple sclerosis resulted in no new confirmed cases of progressive multifocal leukoencephalopathy (PML), a rare and deadly neurological disorder. The companies previously reported three confirmed cases of PML in Tysabri users, two of which were fatal. A total of five suspected cases of PML linked to Tysabri use have been reported to federal regulators. An ongoing safety evaluation in Crohn's disease and rheumatoid arthritis is on track to be completed by the end of the summer, the companies said. They anticipate making submissions to regulatory authorities in early fall of 2005. Biogen Idec and Elan voluntarily withdrew Tysabri from the market in February.