Abatacept shows promise in refractory juvenile dermatomyositis

Some patients with treatment-refractory juvenile dermatomyositis (JDM) appear to respond to abatacept, as shown in a small study.

The 24-week study included 10 paediatric patients aged at least 7 years who had moderate disease activity. Researchers assessed the International Myositis Assessment and Clinical Studies Group (IMACS) Definition of Improvement (DOI) as the primary endpoint. Secondary endpoints included safety, change in core set activity measures (CSMs) of IMACS and Pediatric Rheumatology International Trials Organization (PRINTO), and the ACR-EULAR response criteria for JDM.

Thigh magnetic resonance imaging (MRI) and interferon gene score (IFNGS) on whole-blood RNA were also performed.

DOI occurred in five patients at week 12 and in nine patients at week 24. Of the nine patients, two had minimal, four had moderate, and three had major improvement according to ACR-EULAR response criteria using IMACS CSMs. All CSMs, except muscle enzymes, improved from baseline at weeks 12 and 24.

At week 24, daily corticosteroid dose dropped from a mean of 16.7 mg at baseline to 10.2 mg (p=0.002), average MRI muscle oedema score decreased from 5.3 at baseline to 2.3 (p=0.01), and six patients had down-trending IFNGS and galectin-9.

Of note, reductions in IFNGS, IP-10, galectin-9, and IL-2 were associated with improvement in disease activity and in MRI muscle oedema.

There were 11 cases of grade 2 or 3 treatment-emergent adverse events.