Efficacy and safety of low-dose interleukin-2 in combination with methotrexate in patients with active rheumatoid arthritis: a randomized, double-blind, placebo-controlled phase 2 trial

Abstract Rheumatoid arthritis (RA) is an aggressive autoimmune arthritis, and current therapies remain unsatisfactory due to low remission rate and substantially adverse effects. Low-dose interleukin-2 (Ld-IL2) is potentially a therapeutic approach to further improve the disease. This randomized, double-blind, placebo-controlled trial was undertaken to evaluate the efficacy and safety of Ld-IL2 in patients with active RA. Patients were randomly assigned (1:1) to receive Ld-IL2, defined as a dose of 1 million IU, or placebo in a 12-week trial with a 12-week follow-up. Three cycles of Ld-IL2 or placebo were administered subcutaneously every other day for 2 weeks (a total of 7 doses), followed by a 2-week break. All patients received a stable dose of methotrexate (MTX). The primary outcomes were the proportion of patients achieving the ACR20, DAS28-ESR