Elan's breakthrough multiple sclerosis drug (MS) Tysabri will return to market following sanction yesterday by the US Food and Drug Administration (FDA).
However, the US regulator has imposed tight conditions on its use. Most significantly, only patients "who have not responded adequately to, or cannot tolerate, other treatments for MS" will be able to avail of the drug produced by Elan and its US partner Biogen.
The Independent Peripheral and Central Nervous Systems Drug Advisory Group, which in early March unanimously advocated Tysabri's return to market also voted by a narrow majority to recommend that the drug not be restricted to patients who had failed to respond to older and less effective MS drugs.
Elan head of research Dr Lars Ekman last night said the FDA approval was "well in line with the recommendations" of the independent committee.
"We are very pleased with the way the label has been constructed," said Dr Ekman. "It makes Tysabri available for all patients who have left current therapy - and there are an estimated 50,000 of those in the US - and all those who have breakthrough of the disease, which accounts for 50-70 per cent of patients."
He added that Elan felt the language in the label would allow new patients, with their physicians to make "informed decisions" to go for the best current therapy - ie Tysabri.
Tysabri was initially approved by the FDA in November 2004 after a fast-track review process following promising early test results.
Four months later the drug was suspended after two cases of a rare and potentially fatal brain disease, progressive multifocal leukoencephalopathy (PML) emerged among trials patients.
During an extensive review process, a third case was discovered. Two of the patients died.
Tysabri is only the second prescription drug ever to return to market in the US after being suspended for safety reasons. It is expected to be available within a month.
The FDA made it decision ahead of a June 29th deadline. An earlier March deadline had been extended as the regulator and the two companies looked to develop an acceptable risk management plan and labelling for the MS drug.
The drug will be used only in monotherapy - not with other MS therapies or drugs that modify the immune system - for patients with relapsing forms of the disease.
Patients will have to enrol specially to use the drug through registered centres. They will have to indicate that they have discussed and understand the risks involved.
Tysabri patients will have to undergo regular evaluations to ensure they are responding normally to the treatment and not contracting the virus that triggered PML in the three trial patients. All those patients had used other immunosuppressant drugs.
Dr Ekman said the company was delighted both for patients - who were instrumental in pressing for the drug's return - and for the workforce that had developed the drug.
Elan and Biogen have committed to running further studies after the drug returns to market.
The company expects a ruling on the sale of Tysabri in Europe in the next month or so.
Shares in Elan dropped more than 13 per cent in busy trade in New York last night on the news.
