Alefacept is the first biologic agent approved for the treatment of chronic, moderate to severe plaque-type psoriasis. It is a fully human fusion protein, which binds to CD2, blocks costimulatory signaling, and selectively induces apoptosis of activated memory T cells involved in the pathogenesis of psoriasis. Alefacept has a slow onset of action, peaking approximately 18 weeks after the first injection of a 12-week course. However, it has several important advantages over the existing conventional immunosuppressive therapies for psoriasis: it is associated with long remissions without the need for maintenance therapy; its efficacy improves with subsequent courses; and it has a high safety profile. This review summarizes the mechanism of action of alefacept and the results of the clinical trials, with special emphasis on efficacy, pharmacodynamic effects on circulating lymphocytes, and safety and tolerability. Current guidelines based on the best available data to date are also presented.
- Memory T cells