Two pharmaceutical firms have unveiled new results on the safety of a multiple sclerosis treatment.
Biogen Idec and Elan Corporation said more than 21,000 people are now currently taking Tysabri (natalizumab).
In the US, approximately 12,900 patients are on Tysabri therapy commercially, and around 2,500 doctors have prescribed the treatment so far.
And across the world, some 7,500 patients are on the drug commercially, and about 700 are in clinical trials.
There have also been no cases of progressive multifocal leukoencephalopathy (PML) since the medication relaunched in the US and went on sale internationally in July 2006.
Tysabri is approved for relapsing forms of MS in the US and
relapsing-remitting MS in the European Union.
According to data published in the New England Journal of Medicine, after two years of treatment the drug leads to a 68% reduction in the annualised relapse rate compared with a placebo.
In August, the UK’s National Institute for Health and Clinical Excellence (NICE) recommended Tysabri on the NHS for sufferers of rapidly evolving severe relapsing-remitting MS as it prevents immune cells from leaving the bloodstream.
This means they cannot reach areas of inflammation such as MS lesions in the brain and spinal cord.
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