The efficacy and safety of one and two courses of alefacept have been demonstrated in phase 2 and 3 clinical trials, with a course of alefacept defined as 12 weeks of once-weekly treatment followed by 12 weeks of observation.

This randomized, single-center study compared the safety and efficacy of a standard 12-week versus extended 16-week alefacept dosing period in 20 patients with chronic plaque psoriasis.

Both dose groups showed marked improvement in mean Psoriasis Area and Severity Index (PASI) score from baseline through week 24 (between-group difference: not significant). In each group, 60% of patients achieved PASI 50 (≥50% reduction from baseline PASI score) at any time between weeks 12 and 24. For patients who received 16 weeks of alefacept, the mean percentage change from week-12 PASI score was higher and continued to increase through week 24 compared with that for patients who received 12 weeks of alefacept (P < .05). Adverse events were similar between the two groups and comparable with those observed in phase 2 and 3 clinical studies of alefacept.

This was an open-label, single-center study of 20 patients. Further study is warranted to assess the effect of alefacept when administered for more than 12 weeks. Extended dosing with alefacept appeared to have a similar safety profile to 12-week dosing and may offer further benefit to some patients for disease improvement.