Efficacy and safety of low-dose interleukin 2 for Behçet's syndrome: a randomized, placebo-controlled, double-blind, phase 2 clinical trial.

Behçet's syndrome (BS), a chronic vasculitis, leads to recurrent oral ulcers, severely impacting quality of life. Here we report the results of a randomized, double-blind, placebo-controlled trial (NCT04065672) to evaluate the efficacy and safety of low-dose interleukin-2 (LD-IL-2) in BS patients. 60 participants with active oral ulcers are randomly assigned to receive LD-IL-2 or placebo. The primary endpoint is the oral ulcer count at week 12. The LD-IL-2 group has significantly fewer oral ulcers than the placebo group (0.69 ± 1.05 vs. 1.57 ± 0.90, P = 0.001) with greater improvements in ulcer pain, disease activity, and quality of life. No infections or severe adverse events are observed in either group. LD-IL-2 expands regulatory T (Treg) cells and decreased the ratio of effector T cell to Treg cells. Thus, LD-IL-2 therapy might be an effective and safe treatment in BS patients and is associated with the modulation of CD4 + T cell populations.