A prospective, multinational, open-label extension study in 183 patients with chronic plaque psoriasis determined the efficacy and safety of up to 3 courses of i.m. alefacept (15 mg/week for 12 weeks). The patients had previously been treated with alefacept and received up to 3 additional courses of 12 weeks (A, B and C). Efficacy was assessed by the Physician's Global Assessment (PGA) score at 2 weeks after the final dose of alefacept in each course. At 2 weeks postdosing, 16, 22 and 19% of patients were "clear or almost clear" on the PGA in courses A, B and C, respectively. Those achieving this score at any time were 35, 42 ...