Having just announced that it was cutting jobs to concentrate on promoting Tysabri in Crohn’s disease, Elan Corp and partner Biogen Idec have revealed yet another new case of progressive multifocal leukoencephalopathy in a multiple sclerosis patient being treated with the drug.

In a filing to the US Securities and Exchange Commission, Biogen said that the relevant regulatory agencies had been notified of a confirmed case of PML, a potentially deadly brain infection, in a patient suffering from MS in Europe who had been on Tysabri (natalizumab). The disclosure comes after the firms reported two cases of PML in Europe (in July) and one in the USA in October, so that makes it four cases since Tysabri was reintroduced to the market in July 2006

In the latest case, the filing reveals that the patient received 26 months of Tysabri monotherapy and has a history of prior disease-modifying therapies including beta-interferons. The individual is now under the care of their treating physician, Biogen said.

Ian Hunter at the Dublin-based stockbroker Goodbody noted this morning that by the end of the third quarter there were 34,800 patients on commercial Tysabri therapy, of which 18,000 had been on the drug for over a year, 9,500 for over 18 months and 3,700 for over two years. Given this situation, he added that “it is not unexpected that a further case of PML has surfaced, given that the incidence is still well below the level considered acceptable to the US Food and Drug Administration”, ie one in a 1,000.

Indeed, Mr Hunter added that with two of the three former patients having recovered from the acute phase of PML and receiving physical therapy in the chronic stage (the third is still in the acute phase), “it can be inferred that PML is now being detected early enough to be effectively managed.”

This latest PML case comes at a particularly tricky time for Elan as a high-profile shareholder is calling for the head of the Irish company’s chief executive Kelly Martin, as reported by PharmaTimes World News yesterday.

The co-founder of Crabtree Partners, Jack Sculer, sent a letter to Elan chairman Kyran Mclaughlin complaining about the fact that the company's stock price has fallen from $37 to $7 over the last four months and criticised Mr Martin directly. He asked: “What was the board thinking when they chose a Merrill Lynch employee to be the CEO of Elan? As far as I can see, he has no experience in pharmaceuticals or in managing any type of operation.”

Mr Schuler also complained about “inappropriate and outlandish expenses” for the use of private jets for executives. He said that “I know of no other biotech company that has corporate jets, yet alone a small, struggling one”.