Ireland’s Elan Corporation and Biogen Idec of the USA enjoyed gains in their respective share prices yesterday after speculation abounded once again that their withdrawn multiple sclerosis drug, Tysabri (natalizumab), would return to the market [[04/05/05b]].

Speaking to reporters after the firm’s annual shareholder meeting yesterday, Elan’ chief executive, Kelly Martin, said that Tysabri would find its way back onto the market, given the number of patients requiring therapy and the product’s proven efficacy, according to Reuters. He added that a US Food and Drug Administration investigation into the drug’s safety was set to conclude by the end of the summer, after which time the firm was hoping to hold discussions with the agency regarding the product’s future.

The plug was pulled on Tysabri earlier this year after two patients treated with the drug developed a rare brain infection, one of which was fatal, just weeks after it was launched in the USA [[01/03/05a]]. A third patient has since succumbed to the infection [[31/03/05a]].