Genentech has reported a second case of progressive multifocal leukoencephalopathy which has resulted in the death of a 73-year-old patient who had been treated with the firm’s chronic psoriasis drug Raptiva.

The US biotechnology company has issued a Dear Healthcare Provider letter to inform potential prescribers that the woman in question had taken Raptiva (efalizumab) for about four years before suffering the rare brain infection. The case follows another, which was reported in October, involving a 70-year-old patient who died after taking the treatment for the same length of time.

Genenetech said that the cases suggest that the treatment "likely increases the risk of PML and that prolonged exposure to Raptiva and older age may further increase the risk." The drug's prescribing information was updated in October to include a boxed warning about the risk of serious infections, including PML, in patients who take Raptiva, and Genentech said it is now working with the US Food and Drug Administration “to determine the appropriate next steps”.

Hal Barron, Genentech’s chief medical officer, said that “given the seriousness of PML and its rarity in the general population”, it is important to inform healthcare providers of this second reported case “so that physicians and their patients are equipped to make informed treatment decisions". The firm noted that patients need to talk with their doctor before changing or stopping treatment.