Introduction: Although synthetic and biologic disease-modifying antirheumatic drugs are available, many patients with rheumatoid arthritis have a difficult-to-control disease and need other treatment options. Repository corticotropin injection (RCI) may alleviate symptoms and exacerbations in patients with refractory disease.
Methods: Nine patients with refractory rheumatoid arthritis were included in this study. Patients were maintained on their baseline therapies with a minimum of 7.5 mg prednisone daily. RCI was given daily at 40 U for 7 days. Patients who had an adequate disease response were given 40 U twice weekly through Week 12. For patients who had inadequate disease response, the dose was increased to 80 U daily for 7 days, followed by 80 U twice weekly through Week 12.
Results: The primary endpoint was >1.2 point reduction in the Disease Activity Score 28 using C-reactive protein (DAS28-CRP) at Week 12. Secondary endpoints were improvements in Health Assessment Questionnaire-Disease Index and Functional Assessment of Chronic Illness Therapy scores. Six of the nine patients met the primary endpoint. The average change in DAS28-CRP from baseline to Week 12 was numerically greater with 40 U than with 80 U RCI. Functional Assessment of Chronic Illness Therapy and Health Assessment Questionnaire-Disease Index improved as early as Week 1, and the improvements remained throughout treatment.
Conclusion: There was no association between cortisol levels and low-dose RCI response. No serious adverse events occurred. RCI produced a clinically meaningful reduction in markers of disease activity, improved health-related quality of life, and a favorable safety profile. The response rate to RCI was substantial and shows promise in this difficult-to-treat population.
Keywords: Disease Activity Score 28 using C-reactive protein (DAS28-CRP); biologic failure; health-related quality of life; melanocortin; refractory rheumatoid arthritis; repository corticotropin injection; rheumatoid arthritis.