Elan shares soar on news of possible Tysabri side-effect treatment


SHARES IN drug company Elan bounced more than 10 per cent yesterday after news emerged of a possible treatment for a potentially fatal side effect of its multiple sclerosis therapy, Tysabri.

Biogen Idec, Elan’s partner in the development and sale of Tysabri, is testing the efficacy of a malaria pill developed during the Vietnam war in treating progressive multifocal leukoencephalopathy (PML), the brain infection that has been tied to use of Tysabri, according to Al Sandrock, Biogen’s head of neurology research.

Tysabri was pulled from the market in 2005 after three PML cases were reported. It was reintroduced a year later when US regulators said the medication’s effectiveness, twice that of other MS drugs, outweighed its risks.

However, the threat of PML has affected sales of the treatment which, although a successful drug in commercial terms, is well short of the figures initially expected.

In 2008, Tysabri generated $813 million (€604 million) in revenue.

The companies also reported five new PML cases since July, reigniting concerns of patients who believe a safer Tysabri would be their best treatment option, said John Richert of the US National Multiple Sclerosis Society. Without the risk, sales may more than triple, according to New York-based analyst Eric Schmidt.

Biogen may discuss its Tysabri safety efforts at a meeting today with investors and analysts to present its latest drug research.

Elan’s shares increased by 11.4 per cent to €4.48 in Dublin yesterday following news of the development.

Tysabri, a laboratory-engineered antibody, is designed to suppress the immune attack that leads to MS.

PML occurs when a common germ, called JC virus, mutates, evades the body’s immune defences and penetrates the brain, causing irreversible damage.

Biogen has been seeking a PML treatment since 2005, screening about 2,000 compounds known to fight brain infections.

The drug showing the most promise in laboratory tests was the commonly used malaria pill mefloquine.

A clinical trial is now testing mefloquine in 40 patients with PML from any cause, whether drug-related or from HIV.

The goal is to see whether mefloquine, sold by Roche Holding under the name Lariam, can treat PML when it occurs. The trial is expected to be completed by the end of the year. – (Bloomberg)