Potential blockbuster Tysabri pulled after patient death

pharmafile | March 9, 2005 | News story | Sales and Marketing  

Elan and Biogen Idec have stopped marketing Tysabri (natalizumab), their new multiple sclerosis treatment, and asked doctors not to prescribe it following the death of a patient.

Tysabri was only approved by the FDA in December last year and it had been expected to reach sales of more than $1 billion and eventually overtake the current market leader, Biogen's Avonex (Interferon beta-1a).

Both companies were heavily reliant on the treatment and Elan's share price fell by 70% in New York and Biogen's by 40% on the news.

Burt Adelman, executive vice president, development at Biogen Idec, said: "Our ongoing commitment to MS patients has led us to take these steps. Because we believe in the promising therapeutic benefit of Tysabri, we are working to evaluate this situation thoroughly and expeditiously."

He said that patient safety had to be placed above all other considerations while the matter was worked through.

Chris Jones, chief executive of the MS Trust commented: "The MS Trust is saddened that a drug which had seemed so very effective has now been withdrawn. Clearly Biogen have reacted very responsibly by taking such rapid action, and we hope that once the data has been analysed it will be clearer exactly what has happened in the two cases of multifocal leukoencephalopathy seen in the clinical trial."

Two patients participating in clinical trials of a combination of Tysabri and Avonex developed progressive multifocal leukoencephalopathy (PML) and one of them died. PML is a rare but frequently fatal demyelinating disease of the central nervous system.

Both patients had been taking the drug combination for more than two years. The drug's potential was expected to extend beyond MS, and its marketing partners had filed for a licence to treat Crohn's disease and were examining its suitability as a treatment for rheumatoid arthritis.

There have been no reports of PML in MS patients receiving Tysabri on its own or in patients with Crohn's disease or rheumatoid arthritis in clinical trials of the drug. Likewise, Biogen has not received any reports of the side-effect in patients treated with Avonex alone.

Lars Ekman, executive vice president and president, research and development, Elan, said: "We are working with leading experts and regulatory agencies to responsibly investigate these events and to develop the appropriate path forward."

Biogen and Elan are examining information on the possible risk of PML from the drug's now suspended clinical trials programme to see if these could be re-started and Tysabri returned to the market.

Tysabri is a humanised monoclonal antibody that works in a different way to the MS drugs currently on the market by inhibiting 'adhesion molecules' on the surface of immune cells.

Research suggests this action prevents immune cells from travelling to the brain where they can cause inflammation and damage nerve fibres and their insulation.

Related articles:

Breakthrough MS drug tipped for blockbuster status 

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