Development and use of alefacept to treat psoriasis.

Activated memory T cells, expressing CD2, are key components in the pathogenesis of psoriasis. Alefacept binds to CD2, blocks co-stimulatory signaling, and selectively induces apoptosis of pathogenic T cells. Our objective is to present safety and efficacy results which lead to the new drug application (NDA) of alefacept for the treatment of psoriasis. We reviewed the key phase II and III trials in over 1300 patients and found that during treatment and follow-up of patients receiving 12 weekly intramuscular or intravenous injections of alefacept, about 1/3 will achieve a reduction in psoriasis area and severity index (PASI) of > or =75% and nearly 2/3 a reduction in PASI of > or =50%. Patients who achieved a > or =75% reduction from baseline PASI during or after a single course maintained a > or =50% reduction in PASI for a median duration of >7 months. Among patients who received 2 courses of alefacept, 40% and 71% of patients achieved a > or =75% and > or =50% reduction in PASI, respectively and duration of effect was prolonged. Adverse events in the placebo and active treatment arms did not differ. We conclude that alefacept significantly improves psoriasis and produces durable clinical improvement with a very favorable safety profile.