Elan and Biogen Idec are not abandoning the two drugs withdrawn last week after a patient died during clinical trials.

Biogen co-founder and director Prof Phillip Sharp said he was determined to to get the drugs, Tysabri and Avonex, re-approved for human trials given their particular success in treating Multiple Sclerosis (MS) patients.

He said the two companies are planning fresh negotiations with the US Food and Drug Administration (FDA) to get the drug therapy back into trials and onto the market. He was speaking in Dublin yesterday before delivering a public lecture at University College Dublin.

"We are not walking away at all. No. They represent too big an advance against a disease that controls people's lives. We are not walking away," Prof Sharp declared.

Share values in both companies plummeted after the announcement on February 28th that a US patient taking the two drugs had died. A second patient on the same drug therapy also fell seriously ill and the trial was immediately suspended.

Both patients contracted a comparatively rare illness, multi local leukoencephalopathy (PML).

"We are reassessing everybody to see if PML is seen elsewhere. With that information, we will make plans to proceed with the development of the product," Prof Sharp said.

"Everybody is very concerned with patient safety and PML is a very dramatic problem. We want to be prudent and careful in the development of the drug. We were incredibly impacted and disappointed about this."

Tysabri trials showed that it was "twice as effective as any other treatment" for MS patients. "The combination is better than either one alone."

The company is to enter negotiations with the FDA to establish a safe way to continue trials of the therapy, he added. There was no time frame for these negotiations.

Meanwhile, Biogen announced yesterday that Thomas Bucknum, its executive vice-president and general counsel, had resigned from the company with immediate effect. Last week, it emerged that, according to a US Securities and Exchange Commission (SEC) filing, Mr Bucknum was sold 89,700 shares in Biogen for a profit of $1.94 million (€1.44 million) shortly before the company informed regulators of safety concerns regarding Tysabri.

The SEC filings also show that the company's board of directors approved $4.6 million in 2004 executive cash bonuses. - (Additional reporting by Reuters)