FDA Resurrects an MS Drug Known to Kill

The FDA has decided to bring back a drug that it took off the market last year. The drug, marketed as Tysabri, is meant to help with symptoms of multiple sclerosis. However, in a large scale test, there was one confirmed fatality of a rare brain disease called progressive multifocal leukoencephalopathy (PML) and one additional case (non-fatal). I don't know how rare this PML is, but two cases in a sample of 3,000 seems like a lot.

But the FDA brought it back again anyway. It seems like they have a very high tolerance for the "side effects" of drugs. This columnist is outraged (as he always is).

Read the FDA's reasoning for bringing it back here. I was especially interested to read "No additional cases of PML were found." How many do we need to find??