Swiss biotechnology company Serono has decided to undertake a major post-marketing study of its psoriasis drug Raptiva in Europe to try to lay to rest safety fears about the drug, recently raised by the US Food and Drug Administration.

The FDA added a warning to the labelling for Raptiva (efalizumab) last year, after haemolytic anaemia was seen in two patients taking the drug in clinical trials, and two others after it was approved for marketing. Raptiva is sold in the USA by Genentech.

Serono said the objective of the seven-year pharmacoepidemiological study, which will involve 7,000 adult patients with moderate to severe plaque psoriasis, was to gather additional long-term safety data about Raptiva. The study would also help gather data on the long-term safety profile of other treatments for psoriasis.

Called CLEAREST, the study is a prospective analysis and the primary objective will be to document the incidence of adverse events in patients treated with Raptiva. A secondary objective is to compare the incidence rates of the primary endpoints observed in patients treated with Raptiva with rates observed in the most adequate comparison cohort, i.e. a cohort of patients who have discontinued Raptiva and external comparison with psoriasis patients.

Raptiva was first approved for marketing in Europe in 2004 and in the USA in 2003, but sales momentum has been slow, particularly in Europe where it has been held back by reimbursement issues.

Serono reported Raptiva sales of $33 million last year and has said it expects peak sales from the drug of around $250 million. Meanwhile, Genentech said first-quarter sales of the drug rose 24% to $21 million.