Biogen Idec Inc revealed that patients reporting successful treatment by drug Tysabri increased to 30 percent and sales of its multiple Sclerosis drug crossed $1 billion mark in 2009.

The biotech company is based in Cambridge, Massachusetts and is in planning to launch Fampridine-PR in Europe, which is an oral therapy for improving the walking ability in patients suffering from multiple sclerosis.

The rare brain infection known as progressive multifocal leukoencephalopathy, or PML, is associated with use of Tysbar, which resulted in withdrawal of medicine from the market in 2005 for more than one and half year, but infection again emerged in 2008 but its levels were down to 0.1 percent infected patients.

Jim Mullen, in a statement told that in the end of December 2009, the company had 48,800 customers for Tysabri throughout the world, which includes 24,500 in the U. S., 600 in clinical trials and remaining in the rest of the world.

Tysabri is jointly marketed by Elan Corp Plc of Ireland and Biogen Idec Inc.

The company is expecting the initialization of its trial in the first half of year 2010 for developing a treatment for hemophilia B.