An international, randomized, double-blind, placebo-controlled phase 3 trial of intramuscular alefacept in patients with chronic plaque psoriasis.

BACKGROUND Alefacept, human lymphocyte function-associated antigen 3/immunoglobulin 1 fusion protein, binds to CD2 molecules on the surface of activated T cells, selectively targeting memory-effector (CD45RO+) T cells, which comprise more than 75% of T cells in psoriatic plaques. OBJECTIVE To examine the efficacy and tolerability of intramuscular alefacept. DESIGN International, randomized, double-blind, placebo-controlled, parallel-group trial. PATIENTS A total of 507 patients with chronic plaque psoriasis. INTERVENTION Placebo, 10 mg of alefacept, or 15 mg of alefacept administered once weekly for 12 weeks followed by 12 weeks of observation. MAIN OUTCOME MEASURE Psoriasis Area Severity Index (PASI). RESULTS Alefacept treatment was associated with dose-related significant improvements in PASI from baseline. Throughout the study, a greater percentage of patients in the 15-mg group than in the placebo group achieved a significant reduction in PASI. Of patients in the 15-mg group who achieved at least 75% PASI reduction 2 weeks after the last dose, 71% maintained at least 50% improvement in PASI throughout the 12-week follow-up. There were no opportunistic infections and no cases of disease rebound. CONCLUSION Intramuscular administration of alefacept was a well-tolerated and effective therapy for chronic plaque psoriasis and thus represents a convenient alternative to intravenous dosing.