FDA Suspends Clinical Trials of Glaxo MS Drug

GlaxoSmithKline, Europe’s biggest drug maker, said Wednesday that U.S. regulators suspended clinical trials of its experimental multiple sclerosis drug because it was in the same class as the recently withdrawn Tysabri medication.

Biogen Idec Inc. and Elan Corp. pulled Tysabri from the market Feb. 28 after it was linked to a rare nerve disorder in two patients, one of whom died.

Also on Wednesday, the chief executive of Biogen Idec said the company was still producing the drug in the expectation that it would be able to resume selling it at some point. “I’m fairly optimistic that the drug will return to the market,” James Mullen said in an interview at the SG Cowen & Co. Healthcare Conference in Boston.

The Food and Drug Administration halted clinical trials on all MS drugs in the same class as Tysabri as a “precautionary measure,” Glaxo spokesman Chris Hunter-Ward said.

About 400 study participants have received the MS medication, known as 683699, Hunter-Ward said. Studies had reached the second of three stages of tests generally required before regulators will consider marketing approval. Independent monitors evaluating the data haven’t seen problems with Glaxo’s drug similar to those linked to Tysabri, he said.

“We maintain it’s chemically different,” Hunter-Ward said. “The FDA has taken a precautionary measure and placed a clinical hold on all drugs in the class, of which 699 is one.”

Both Glaxo’s 683699 and Tysabri block a substance called alpha-4 integrin, which is involved in multiple sclerosis. Glaxo’s medicine is given as a pill, whereas Tysabri is administered by intravenous infusion. The firm expects to seek approval of its MS medicine in 2008, Glaxo said Nov. 23 when it updated investors on its drugs in development.

Glaxo is developing the MS treatment with Japan’s Tanabe Seiyaku Co. Shares of London-based Glaxo declined 35 cents to $48.35 on the New York Stock Exchange.

Meanwhile, Biogen Idec is working to determine whether more patients have been affected by the disease. Before the side effects were detected, analysts predicted the drug would have $3 billion in annual sales. Tysabri, the first new type of drug in eight years to treat MS, won U.S. approval in November based on partial results of a two-year study.

Biogen is making Tysabri at a plant in North Carolina and retains the sales representatives hired to promote the product, Mullen said.

Multiple sclerosis is a neurological disorder that affects about 1 million people worldwide and robs patients of muscle coordination and balance, sometimes leading to damaged vision and paralysis.

Also on Wednesday, Biogen Idec warned doctors in a letter that the Avonex multiple sclerosis drug has been linked to a risk of liver damage.