November 26, 2004

Elan’s MS Drug May Also Help Arthritis and Crohn’s Disease

The current buzz about Elan's drug Antegren (natalizumab) centres on its use in multiple sclerosis (MS). It has even greater potential, however, as a new therapy for more common conditions including arthritis, asthma and other auto-immune diseases.

MS affects 6,000 people here or about one per cent of the population. Arthritis affects at least 13 per cent of the general population. If Antegren proves itself as a treatment for arthritis, Elan and its commercialisation partner Biogen Idec could achieve billion-dollar sales worldwide.

Vioxx, the arthritis painkiller withdrawn by US giant Merck & Co two months ago, was worth [euro]2 billion a year. Antegren works in a completely different way to Vioxx and may also be applicable to other auto-immune diseases.

About 20 per cent of the world population suffers from an auto- immune disease, according to Irish researchers.

Auto-immune diseases occur when the body's defence systems begin to damage healthy tissues. The immune cells meant to protect against bacteria and viruses inexplicably attack normal cells, triggering a cascade of events that leads to cell-destruction and inflammation.

In MS, the damage is done to the myelin that protects nerve tissues. In arthritis, it is cells in the joints. In each case, the initial insult attracts massive "friendly fire", with waves of immune cells rushing in to cause unwanted collateral damage. Antegren acts as a brake on this cascade, in effect shutting it down before it can begin. The signal that provokes the immune cells is not sent and no damage is caused.

In June 2004, the US Food and Drug Administration (FDA) sanctioned a "priority review and accelerated approval" for the drug after very promising results in MS patients. The latest study shows patients experienced 66 per cent fewer disease relapses when receiving Antegren.

Significantly, however, Elan also has human trials underway using Antegren in patients with two other auto-immune diseases, Crohn's disease and arthritis. The drug looks promising in both.

Antegren is a cloned human antibody able to connect to the cells that initiate the immune system response - blocking it in the process. Mr Martin Hemler and colleagues first identified the Antegren molecule in 1987.

This intellectual property was acquired by Elan in 1996 with the purchase of Athena Neurosciences. Elan continued to work on the discovery, studying its interaction with other immune cells in MS at its San Francisco research base.

In 1992, T A Yednock and colleagues confirmed that Antegren-type antibodies could block auto-immune disease in animals, publishing their findings in Nature.

By 1994 Elan had "humanised" the antibodies and applied to the FDA to evaluate Antegren in MS patients. Elan staff in the Republic were involved in the "development and commercialisation" effort.