Alefacept: a novel biologic in the treatment of psoriasis.

Recognition of psoriasis as a T-cell-mediated immune disease has led to the development of various therapeutic approaches directed against the T cell and T-cell processes such as activation, trafficking and cytokine release. The novel and selective biologic agent alefacept, with an effect of selective apoptotic reduction in memory-effector T cells, has been given FDA approval for the treatment of adult patients with moderate to severe chronic plaque psoriasis who are candidates for systemic therapy or phototherapy. The clinical profile of this novel biologic agent is presented here. Two pivotal multicenter, randomized, placebo-controlled, double-blind studies enrolling 1060 patients were designed to support the efficacy and safety of alefacept in the treatment of moderate to severe chronic plaque psoriasis. With either intramuscular or intravenous administration, well over half of patients treated with a single course of alefacept achieved a 50% reduction in PASI (Psoriasis Area and Severity Index), and a second course of therapy provided further benefit by increasing response rates and providing long-lasting off-treatment responses regardless of the route of administration. In all studies, alefacept was well tolerated. There was no evidence of an increased risk of infections or malignancies and no opportunistic infections were reported. Consistent with its composition as a fully human fusion protein, alefacept had a low incidence of immunogenicity and no evidence of an increased rate of antibody development over time. There was no evidence that primary or secondary responses to a new antigen or memory response to a recall antigen were blunted in patients treated with alefacept. In conclusion, alefacept is the first biologic therapy to demonstrate positive effects in an immune-mediated disease while maintaining immune responses to novel and recall antigens. This selective effect on the immune system distinguishes alefacept from immunosuppressive therapies that are nonselective.