Elan Corp PLC and Biogen Idec Inc announced the start of Phase I/II trials with Tysabri, their multiple scelerosis and Crohn´s disease drug, with the goal of determining the safety and effectiveness of this drug in patients with multiple myeloma, a cancer of bone marrow plasma cells.

The patients have either not responded to previous treatments or their cancer has returned after initially responding to treatment.

Up to 12 patients will be involved in the phase I dosing trial, and as many as 30 patients will receive varying doses after the most effective levels have been identified. They will be given intravenous Tysabri once every four weeks for six months.

The treatments for multiple myeloma are led by biotech Celgene, with several drugs on the market: Revlimid, with sales for $ 613 million dollars in the first 6 months of the year; Thalomid, sales for $ 245 million dollars in the same period; and Alkeran.

Johnson & Johnson´s Velcade is another rival, with earnings for $ 389 million dollars in the first half of 2008.

Tysabri itself had sales for $ 262 million dollars in the first six months of this year – it was approved initially for multiple sclerosis in November 2004, but was taken off the market in February 2005 after it was linked to several cases of deaths caused by progressive multifocal leukoencephalopathy (PML), a rare brain infection. The drug returned to the market in mid-2006, under a strict controlled program, yet this year there have been several more cases of PML detected in patients on Tysabri.

Some 33,000 multiple scelerosis patients worldwide are using this product.