Therapy: Targeted but not trouble-free: efalizumab and PML.

In April 2009, efalizumab was withdrawn from the market for the treatment of psoriasis after reports emerged of an association between long-term therapy and the development of progressive multifocal leukoencephalopathy (PML). This event highlights an urgent need for greater awareness and research into the screening, diagnosis and treatment of this potentially fatal disease in patients undergoing immunosuppressive therapy for chronic inflammatory disorders.