Primary Outcome Measures:
- To evaluate the safety of treating subjects with up to 12 additional doses of alefacept 15 mg IM following a standard 12-week course of AMEVIVE. [ Time Frame: 16 weeks, 20 weeks or 24 weeks ] [ Designated as safety issue: No ]
Secondary Outcome Measures:
- The proportion of subjects who achieve moderate improvement, significant improvement or clear, as assessed by the PQA score, at any time during the study, [ Time Frame: End of study ] [ Designated as safety issue: No ]
- The cumulative change in PQA score from screening visit to best PQA score at any time in the study, [ Time Frame: End of study ] [ Designated as safety issue: No ]
- Association of the total number of doses received with the best efficacy reached, as assessed by PQA score, at any time during the study, [ Time Frame: End of study ] [ Designated as safety issue: No ]
- Time to re-treatment for subjects who achieve moderate improvement, significant improvement or clear, as assessed by the PQA score, at any time during the study, [ Time Frame: End of study ] [ Designated as safety issue: No ]
- The cumulative change in SSA score from screening visit to best SSA score at any time in the study, [ Time Frame: End of study ] [ Designated as safety issue: No ]
- Association of the total number of doses received with the best efficacy reached, as assessed by SSA score, at any time during the study, and [ Time Frame: End of study ] [ Designated as safety issue: No ]
- Association of subject assessment of efficacy with physician assessment of efficacy as measured by the SSA score and PQA score respectively. [ Time Frame: End of study ] [ Designated as safety issue: No ]
Male and female subjects at least 18 years of age with moderate to severe plaque psoriasis treated with 12 weeks of alefacept 15 mg IM and who have not achieved the desired response.
Dosing Groups: Subjects will receive either 4, 8, or 12 doses of alefacept 15 mg IM weekly immediately (within 14 days) following a standard 12-dose course of AMEVIVE® 15 mg IM. Determination of number of doses will be based on physician qualitative assessment at weeks 4 and 8.