Elan shares rose by over 10 per cent to be trading at €6 this morning following reports that its controversial drug Tysabri may still be of use to MS sufferers.
In the upcoming edition of the New England Journal of Medicine( NEJM), several medical experts say although they see a link between the use of Tysabri and a deadly brain disease, they also see a possibility of the drug being of use if patients are closely monitored.
Elan and partner Biogen pulled Tysabri from the market in February, after two cases of progressive multifocal leukoencephalopathy (PML) surfaced in patients given the drug during clinical trials.
In an editorial due to run later this month, the editor-in-chief of NEJM, Dr Jeffrey Drazen, says further study is needed to determine whether the benefits of Tysabri, also known as natalizumab, justify its risks.
"In the case of natalizumab, there is a dilemma. On the one hand, it appears to be a promising therapy for multiple sclerosis and has raised the hopes of patients with this debilitating condition; on the other hand, the complication of PML can be fatal," wrote Dr Drazen.
"Given these data, the association between treatment with natalizumab and the occurrence of PML seems clear. What we do not know is the magnitude of the risk of PML per year of exposure," he wrote.
Another NEJMeditorial speculated that PML victims might stand a better chance of recovering if Tysabri was discontinued in the very early stages of the disease.
In a letter that will appear in the same issue as Dr Drazen's editorial, Biogen researchers offered hope that Tysabri could return to the marketplace if patients are strictly monitored for the onset of PML.
Biogen and Elan suspended all sales and testing of Tysabri in late February after two patients using the drug in a clinical trial were reported to have contracted PML.
A third PML victim, also from a clinical trial, was identified in March. A fourth suspected case of the disease was reported to the Food and Drug Administration recently.
Of the three confirmed PML cases, two of the patients have died, while a third survived. The fourth suspected victim is also alive, according to Biogen and the FDA.
Three of the patients, who suffered from multiple sclerosis, used Tysabri along with another Biogen drug, Avonex. A fourth patient, who suffered from Crohn's, had been taking Tysabri, along with a variety of other medications for his condition.