Treatment of Active Idiopathic Inflammatory Myopathies by Low-Dose Interleukin-2: A Prospective Cohort Pilot Study.

Abstract

IntroductionTreatment of idiopathic inflammatory myopathies (IIMs) is challenging due to a lack of safe and efficacious medication. Low-dose interleukin-2 (IL-2) treatment emerges as a new option in active IIMs. This study aims to explore the clinical and immunological effects of low-dose IL-2 in patients with active IIMs.MethodsEighteen patients with active IIMs were enrolled and received 1 × 106 IU of IL-2 subcutaneously every other day for 12 weeks on top of standard care. The primary endpoint for the trial was change in percentage of regulatory T (Treg) cells in total CD4+ T cells at week 12. The secondary endpoints included the International Myositis Assessment and Clinical Studies (IMACS) definition of improvement (DOI), the 2016 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) myositis response criteria, safety, and steroid-sparing effect at weeks 12 and 24.ResultsWith low-dose IL-2 treatment, 77.78% (14/18) patients achieved IMACS DOI and 83.33% (15/18) patients met the 2016 ACR/EULAR myositis response criteria at week 12. All individual core set measures (CSMs) including PhGA, PGA and HAQ-DI, muscle enzymes, MMT-8 and extramuscular activity were improved at week 12. The cutaneous dermatomyositis disease area and severity index activity score (CDASI-a) decreased significantly from 7 (4.5, 13) to 2 (0, 7) after IL-2 administration (P < 0.001). Proportion of Treg cells significantly increased with low-dose IL-2 treatment at week 12 (8.97% [5.77, 9.89%] vs. 15.2% [10.4, 17.3%], P = 0.009). There were no serious adverse events.ConclusionsLow-dose IL-2 was effective in active IIMs and well tolerated. The amelioration of disease activity may associate with promotion of Tregs.Trial RegistrationClinicalTrials.gov identifier, NCT04062019.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40744-021-00301-3.