Treatment with repository corticotropin injection (RCI) is effective in approximately 70% of adult patients with dermatomyositis (DM) and polymyositis (PM) refractory to glucocorticoid and traditional immunosuppressive agents, according to results of a recent prospective, open-label pilot study (ClinicalTrials.gov identifier: NCT01906372) published in the Annals of the Rheumatic Diseases.
Adults with refractory DM and PM were enrolled in 1 of 2 centers. Inclusion criteria included having refractory disease, defined as having failed a glucocorticoid and/or ≥1 immunosuppressive drug, together with active disease, defined as significant muscle weakness and >2 additional abnormal core set measures (CSMs), or a cutaneous 10 cm visual analogue scale score of ≥3 cm and at least 3 other abnormal CSMs. Patients received RCI 80 units administered subcutaneously 2 times per week for 24 weeks.
The primary endpoint of the study was the International Myositis Assessment and Clinical Studies definition of improvement, which includes 3 of any of the 6 CSMs improving by ≥20% and ≤2 CSMs worsening by ≥25%. Secondary endpoints included safety, tolerability, steroid-sparing, and 2016 American College of Rheumatology/European League Against Rheumatism myositis response criteria.
A total of 10 participants >18 years of age completed the study: 6 with DM and 4 with PM. Among the 10 patients, 7 met the primary endpoint of efficacy at a median of 8 weeks. A significant reduction in mean prednisone dose from baseline (18.5±15.7 mg) to last follow-up (2.3±3.2 mg; P <.01) was reported.
Most of the CSMs improved at week 24 compared with baseline, with muscle strength improving by a median of >10% and physician global assessment by a median of >40% in all patients. The use of RCI was considered to be safe and tolerable. No participants reported significant weight gain, an increase in hemoglobin A1c, or cushingoid features.
The investigators concluded that although the findings from the study demonstrate the efficacy, safety, and tolerability of RCI use in patients with DM and PM, given the cost of this treatment, it is unlikely to be recommended as first-line therapy in this population. They suggest that a cost-benefit analysis might be advantageous in defining the proper place of RCI in the treatment algorithm of myositis.
Aggarwal R, Marder G, Koontz DC, Nandkumar P, Qi Z, Oddis CV. Efficacy and safety of adrenocorticotropic hormone gel in refractory dermatomyositis and polymyositis [published online December 13, 2017]. Ann Rheum Dis. doi: 10.1136/annrheumdis-2017-2120