Efalizumab: new drug. Plaque psoriasis: too many unknowns

(1) Plaque psoriasis is a chronic skin disease for which there is no definitive treatment. Topical therapy is usually tried first. (2) Efalizumab is an immunosuppressant drug marketed for the treatment of adults with moderate to severe plaque psoriasis, when other systemic treatments (ciclosporin and methotrexate) or phototherapy (PUVA therapy, etc.) are ineffective or contraindicated. (3) Clinical evaluation of efalizumab is based on 5 double-blind placebo-controlled trials. In 4 of these trials the endpoint for efficacy was the number of patients who had an improvement of at least 75% in the psoriasis area severity index (PASI) score after 12 weeks of treatment. With efalizumab 1 mg/kg per week, about 25% of patients reached this target, compared with about 4% of patients in the placebo group. Efficacy was not improved by doubling the efalizumab dose. Another trial focused on adverse effects. (4) Most patients relapsed within an average of two months following treatment withdrawal. Some patients worsened after stopping treatment. (5) The most frequent short-term adverse effect is a flu-like syndrome, which affects about 50% of patients. Adverse events observed in clinical trials included skin cancer, severe infections, aggravation or rebound of psoriasis after treatment cessation, thrombocytopenia, hyperleukocytosis, hypersensitivity reactions, and elevated liver enzyme levels. (6) In France treatment cost is around 1000 euros per month, a bit less than etanercept treatment. (7) In practice, efalizumab currently has no place in the treatment of plaque psoriasis in adults, partly due to the absence of comparisons with existing treatments, and partly because of the risk of serious adverse effects.