Elan Extends Tysabri's Reach

Pharmaceutical investors often forget that places beyond the United States and European Union have their own regulatory bodies that approve drugs -- and that some of these markets can be quite lucrative. Canada, Japan, and Australia are home to some of the biggest economies in the world, and they all have their own independent drug-regulation entities.

Smartly realizing the opportunity for sales growth, biopharmaceutical company Elan (NYSE: ELN - News) and partner Biogen Idec (Nasdaq: BIIB - News) have been diligently attempting to gain approval for the companies' multiple sclerosis product Tysabri in some of those other parts of the world. Yesterday, they announced a bit of success -- Canada's drug-regulatory agency has approved Tysabri to treat relapsing-remitting MS, the most common subtype of the disease.

To put this in perspective, Canada has possibly the highest rate of MS in the whole world. An estimated 55,000 to 75,000 Canadians suffer from the disease -- that's nearly one-fifth the estimated number of patients in the United States.

Tysabri, natalizumab, is a monoclonal antibody. This compound is the first of several antibodies in the pipeline targeting different steps in the immune dysfunction that leads to the clinical condition we call MS.

The exact mechanism of action by which natalizumab exerts its effects in multiple sclerosis is not fully defined. MS is believed to develop when activated inflammatory cells, including T cells, cross the blood brain barrier. No one is sure how the inflammatory cells are activated, but the result is the presence of highly active inflammatory cells within the CNS causing destruction of the "insulating" myelin sheath around nerves. Once damaged, the nerves cease functioning normally and the neurologic effects become the symptoms of MS.

Before the inflammatory cells can cross into the CNS, they must bind to the lining of the blood vessels, the endothelium. Natalizumab is thought to work by preventing this binding and hence stopping the migration of the damaging cells.

ELN closed down today 21 cents. I am getting in on the nonetheless.