Cyclophosphamide Pulse Therapy in the Treatment of Systemic Sclerosis Associated Interstitial Lung Disease: An Observational Study

Introduction: Scleroderma is a multisystem autoimmune connective tissue disease with approximately 90% of patients having lung involvement. It is the leading cause of morbidity and mortality in scleroderma. There is no effective treatment once there is lung involvement in the form of fibrosis. Study setting: Conducted in a tertiary care center between January 2017 and December 2019. Aim: To evaluate the efficacy of intravenous cyclophosphamide in patients with scleroderma-associated interstitial lung disease (ILD). Study population: Symptomatic patient with scleroderma with high-resolution computed tomography (HRCT)-proven non-specific interstitial pneumonia (NSIP)-pattern ILD. Methodology: Patients received 12 cycles of cyclophosphamide at a dose of 10 mg/kg every 4 weeks. Patients were followed up for 1 year after treatment completion. A six-minute walk test (6MWT) and spirometry were done at baseline and then every 6 months up to 2 years. Diffusing capacity of lung for carbon monoxide (DLCO) was done at baseline and then yearly for up to 2 years. Results: A total of 38 patients completed the study. The majority of patients had diffuse cutaneous type of systemic sclerosis. Throughout the study period, there was a gradual worsening of dyspnea as measured by the Modified Medical Research Council (mMRC) scale. Mean forced vital capacity (FVC) improved with 1 year of treatment, but later steadily decreased during follow-up. Similarly, DLCO also improved during 1-year treatment, but the improvement was not sustained during follow-up. There was a statistically significant improvement in 6MWD at the end of 6 months. This was followed by a gradual fall in 6MWD during follow-up. The only adverse event noted was persistent leukopenia in one patient. Conclusion: Intravenous pulse cyclophosphamide therapy in patients with scleroderma-associated ILD is associated with stabilization of pulmonary function during the treatment period, but not maintained during follow-up.