Infusions of mesenchymal stromal cell (MSC) for juvenile idiopathic arthritis (JIA) have demonstrated safety among a small population, according to study results recently published in Rheumatology (Oxford); however, macrophage activation syndrome flare remains a risk among persons with systemic onset JIA.

This single-center, phase 1b, open-label intervention study included 6 individuals with JIA whose median disease duration was 9.2 years. All participants had active arthritis, and corticosteroids, methotrexate, and a median of 5 biological treatments had all been ineffective. All participants visited the study center 9 times and were given intravenous infusions of allogeneic MSC (2 million/kg) derived from bone marrow.

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The number of adverse events per 3-month postinfusion period compared with the previous 3 months constituted the primary outcome. The Fisher’s exact test was used to compare adverse events before and after infusion, and a 2-tailed Wilcoxon signed Ranks test was used to compare end-of-study results with baseline.

Of the study’s participants, all received an initial MSC infusion and 3 participants received a second infusion. No severe infusion reactions occurred, and adverse events decreased between pretreatment and posttreatment; however, one participant with systemic onset JIA experienced a macrophage activation syndrome flare 7 weeks after the infusion and 9 weeks after discontinuing tocilizumab, but this participant had a medical history with the syndrome.

Eight weeks after a single infusion, Visual Analogue Scale (VAS) well-being decreased significantly from 75 to 56, Juvenile Arthritis Disease Activity Score-71 (JADAS-71) decreased from 24.5 to 11, and Clinical Juvenile Arthritis Disease Activity Score-10 (cJADAS10) decreased from 18 to 10.6.

The study researchers concluded that “Four of six patients showed a decrease of clinically active joints 8 weeks after the first MSC administration, with a decrease of [C-reactive protein] and [erythrocyte sedimentation rate] in three of the four patients with an elevated value at the start. In the six study patients, only JADAS-71, cJADAS10 and the VAS well-being decreased significantly in that short period. The median scores of the patient reported outcome measures of VAS pain, Childhood Health Assessment Questionnaire and Quality of Life all improved non-significantly during that same episode.”

Reference

Swart JF, de Roock S, Nievelstein RAJ, et al. Bone-marrow derived mesenchymal stromal cells infusion in therapy refractory juvenile idiopathic arthritis patients [published online April 27, 2019]. Rhematology (Oxford). doi:10.1093/rheumatology/kez157