Aim To evaluate the efficacy, safety, tolerability and steroid-sparing effect of repository corticotropin injection (RCI), in an open-label clinical trial, in refractory adult polymyositis (PM) and dermatomyositis (DM).
Methods Adults with refractory PM and DM were enrolled by two centres. Inclusion criteria included refractory disease defined as failing glucocorticoid and/or ≥1 immunosuppressive agent, as well as 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 three other abnormal CSMs. All patients received RCI of 80 units subcutaneously twice weekly for 24 weeks. The primary end point for the trial was the International Myositis Assessment and Clinical Studies definition of improvement. Secondary end points included safety, tolerability, steroid-sparing as well as the 2016 American College of Rheumatology (ACR)/European League Against Rheumatism myositis response criteria (EULAR)
Results Ten of the 11 enrolled subjects (6 DM, 4 PM) completed the study. Seven of 10 met the primary end point of efficacy at a median of 8 weeks. There was a significant decrease in prednisone dose from baseline to conclusion (18.5 (15.7) vs 2.3 (3.2); P<0.01). Most individual CSMs improved at week 24 compared with the baseline, with the muscle strength improving by >10% and the physician global by >40%. RCI was considered safe and tolerable. No patient developed significant weight gain or an increase of haemoglobin A1c or cushingoid features.
Conclusion Treatment with RCI was effective in 70% of patients, safe and tolerable, and led to a steroid dose reduction in patients with adult myositis refractory to glucocorticoid and traditional immunosuppressive drugs.
Trial registration number NCT01906372; Results.
- autoimmune diseases
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Handling editor Tore K Kvien
Contributors RA and CVO planned the study and wrote the protocol. RA, CVO and GM enrolled patients and evaluated outcome measures. DCK and PN executed the study from patient enrolment to data collection, to data management. ZQ planned the biospecimen and laboratory data collection, and executed the biospecimen sample collection and laboratory results. All authors participated in data analysis and manuscript write-up.
Funding This was an investigator-initiated clinical trial funded by Mallinckrodt.
Competing interests RA, CVO and GM received an honorarium from Mallinckrodt for an advisory board unrelated to this trial.
Ethics approval University of Pittsburgh IRB. The protocol was approved by the Institutional Review Board at each location.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data used for the publication and additional unpublished data from the study can be shared with experienced myositis researchers upon request to PI.