Intravenous cyclophosphamide improves functional outcomes in interstitial lung disease related to idiopathic inflammatory myopathies

OBJECTIVE: To compare the efficacy, toxicity and glucocorticoid (GC)-sparing effects of intravenous cyclophosphamide (iv CYC) with other immunosuppressive regimes as the induction treatment for Idiopathic Inflammatory Myopathy-Related Interstitial Lung Disease (IIM-ILD). METHODS: Observational comparative study of patients with IIM-ILD from the EPIMAR and Cruces cohorts. The main efficacy outcome was a 6 to 12-month improvement >10% in the forced vital capacity (FVC) from baseline. RESULTS: Overall, 47 patients were included: 22 (47%) in the CYC group and 25 (53%) in the non-CYC group (32% azathioprine, 28% GC alone, 20% mycophenolate, 16% calcineurin-inhibitors and methotrexate and 4% rituximab). 81% patients were female with a mean age of 50.4 years. FVC improvement was achieved by 64% patients in the CYC group vs. 32% in the non-CYC group (p=0.03). In the logistic regression model, CYC was identified as the only independent predictor of FVC improvement (OR=3.97, 95% CI 1.07-14.75). Patients in the CYC group received more methyl-prednisolone pulses (MP) (59% vs. 28% in the non-CYC group, p=0.03), less initial GCs doses >30mg/d (19% vs. 77%, p=0.001) and lower 6-month average doses of prednisone (11mg/d vs. 31.1mg/d, p=0.001). CONCLUSION: iv CYC showed better functional outcomes than other immunosuppressants in IIM-ILD. The additional use of MP is likely to potentiate the effects of CYC and allows lowering prednisone doses. Therefore, CYC in combination with MP could be considered as the first line induction therapy in IIM-ILD, without limiting its use to rapidly progressive, life-threatening or refractory disease.