SHARES IN Elan plummeted almost 50 per cent early yesterday after news emerged of another case of PML, a rare brain infection, in a patient on its blockbuster multiple sclerosis drug Tysabri. The shares later recovered some poise to close on €4.92, down almost 16 per cent on the day.
The case is the third since the drug returned to the market in 2006 and the first in the US.
Elan and US partner Biogen had previously suspended sales of the drug just weeks after its market launch when three earlier cases of the often-fatal brain disease were diagnosed in patients.
Labelling on the drug states there is a one in 1,000 risk of patients developing progressive multifocal leukoencephalopathy (PML). Elan chief executive Kelly Martin reported last week that 35,500 people globally were being treated with Tysabri.
"If people hadn't been expecting another case, they were naive," said Bret Holley, an analyst for Oppenheimer. "I don't think this will negatively affect prescriptions any further."
Elan last week reported that Tysabri had recorded sales of £237 million in the three months to the end of September, despite the July news of two PML cases in Europe - the first since the drug returned to market. Of those, one had responded well to treatment.
The patient at the centre of yesterday's announcement had received just 14 infusions of Tysabri before PML was diagnosed.
"The negative sentiment around a further PML case is likely to keep the pressure on Elan's share price," Ian Hunter, a Goodbody Stockbrokers analyst, wrote in a note to clients yesterday. However, he said the new case should "do little to projected numbers of patients on Tysabri".
Prof Michael Hutchinson, a consultant neurologist at St Vincent's hospital in Dublin, said patients on Tysabri were suffering from very aggressive MS for which there was no other adequate treatment. "They are fully informed about the risks and carefully monitored every month" when they arrive for their treatment, he said.
Up to 300 MS patients in Ireland are being treated with Tysabri, some for as long as four years.
