Elan shares were suspended from trading at lunchtime in Dublin yesterday as the US drug regulator opened a two-day hearing on the future of the company's breakthrough multiple sclerosis (MS) drug, Tysabri.

The stock jumped almost 10 per cent in morning trade in Dublin as investors bet that the Food and Drug Administration's (FDA) outside experts on the advisory committee would approve the return to market of Tysabri for at least some patients.

The shares, which did not trade at all in the US yesterday, ended 70 cent or 6.6 per cent stronger on €11.30. Elan shares have weakened recently amid adverse US analyst comment and wariness ahead of yesterday's meeting.

The two-day meeting, in which Elan's US partner Biogen Idec is leading the case for the drug, opened yesterday with an overview of the issues from Dr Russell Katz, director of the FDA's division of neurology products.

He said the FDA did not believe there was any way currently to tell who is at risk of progressive multifocal encephalopathy (PML), the disease that led to the suspension of the drug last year just months after it won FDA approval.

"We fully expect additional cases of PML, many likely to be fatal," Dr Katz said.

Biogen said the MS drug should return to the market but with tight controls to quickly spot cases of a life-threatening brain infection.

Future use should be reserved for patients who are not taking other MS drugs and do not have weakened immune systems, Biogen said.

The company proposed a strong "black-box" warning that patients could develop PML, the company said.

Later yesterday, the panel was due to hear public testimony, including appeals from MS patients who want the drug back on the market.

The advisory panel, a group of experts from outside the FDA, is scheduled to make recommendations today on Tysabri.

The FDA will make the final decision, but the agency usually follows advice from its outside panels. - (Additional reporting, Reuters)