Previous Biogen studies have provided experience with the tolerability, immunogenicity, and efficacy of a single and multiple 12-week courses of therapy of alefacept. At this stage, experience in larger studies, as well as the FDA-approved labeling, is confined to treatment courses of 12 weeks. The purpose of the present study is to offer an extended course of therapy with alefacept.

Twenty statistically matched patients (15 males, 5 females, aged between 28 and 70 years, median 50 years) with moderate to severe psoriasis (PASI: 7-36) were included in this study. They were treated with 15 mg alefacept i.m. weekly. Peripheral blood was taken prior to first alefacept application and then weekly until week five and thereafter every second week, until the end of treatment at week 13. At the same time points severity of disease and thereby possible reduction of symptoms was evaluated applying the PASI. Investigators analysing the samples were blinded to the outcome of the study. The protocol concerning human subjects was approved by the ethics commission of the Charité University Medicine Berlin Campus Mitte, Germany .

Inclusion Criteria:

1. Must give written informed consent.
2. Must require systemic therapy or phototherapy for their psoriasis, as determined by the investigator prior to Visit 1.

Exclusion Criteria:

1. Female subjects who are not postmenopausal for at least 1 year, surgically sterile, or willing to practice effective contraception during the study. Nursing mothers, pregnant women and women planning to become pregnant while on study are to be excluded.
2. Current enrollment in any investigational study in which the subject is receiving any type of drug, biologic, or non-drug therapy (participation in registry-type studies is allowed).
3. Serious local infection (e.g., abscess) or systemic infection (e.g., pneumonia, septicemia) within the 3 months prior to the first dose of investigational drug.
4. Any subject whose CD4+ lymphocyte count at study entry is less than 404 cells/mm3.
5. Treatment with another investigational drug or approved therapy for investigational use within 28 days prior to investigational drug administration.
6. Treatment with systemic retinoids, systemic steroids, methotrexate, cyclosporine, azathioprine, thioguanine or other systemic immunosuppressant agents within the 28 days prior to investigational drug administration.
7. Phototherapy, including Ultraviolet B (UVB) and Psoralen + Ultraviolet A (PUVA), within 28 days prior to investigational drug administration.
8. Known HIV+, known viral Hepatitis infection, known tuberculosis infection.