Purpose: To investigate the safety and efficacy of daclizumab (Zenapax, humanized anti-Tac, HAT) in controlling the ocular manifestations of Behçet's disease.
Design: Randomized, placebo-controlled, double-masked clinical trial.
Participants: Seventeen participants with Behçet's disease experiencing at least two prior ocular attacks and requiring treatment with immunosuppressive agents for the ocular complications of Behçet's disease.
Methods: Participants received either intravenous placebo or daclizumab (1 mg/kg) infusions every two weeks for six weeks, then every four weeks while continuing their standard immunosuppressive regimens. If clinically indicated, tapering of the standard immunosuppressive medications was allowed after six months of study enrollment. Complete ocular and physical examinations and an adverse event assessment were performed at baseline and prior to each study infusion.
Main outcome measures: Primary safety endpoints were the development of a life-threatening complication or a severe opportunistic infection. Primary efficacy outcomes were the number of ocular attacks and an assessment of systemic immunosuppressive medications required during the study, including the ability to taper concomitant immunosuppressive therapy.
Results: Nine participants randomized to daclizumab and eight to placebo were followed monthly. Follow-up ranged from one to 34 months, with a median follow-up of 15 months. Two participants randomized to daclizumab discontinued study therapy prior to the end of the study for personal reasons. No participant experienced a safety endpoint, and visual acuity remained stable in all participants during the course of the study. Ten participants (six daclizumab, four placebo) experienced ocular attacks requiring therapy. The median ocular attack rate during the study was greater in the daclizumab arm than the placebo arm (median 1.27 vs. 0.17 attacks/year, respectively). Participants in the placebo arm also experienced a greater reduction in the immunosuppressive medication score compared to participants receiving daclizumab (median -4.0 vs. -1.0, respectively).
Conclusions: The observed results in the placebo group demonstrate that careful follow-up and treatment with standard combination immunosuppressive therapy can be effective for the management of the ocular complications of Behçet's disease. In our small study, there was no suggestion that daclizumab was beneficial in comparison with placebo. However, the low observed attack rate limited our ability to make a definitive treatment group comparison.