Mycophenolate Mofetil Improves Exercise Tolerance in Systemic Sclerosis Patients with Interstitial Lung Disease: A Pilot Study

INTRODUCTION: Systemic sclerosis (SSc) is an autoimmune disease characterized by the overproduction of collagen leading to fibrosis of the skin and internal organs. Interstitial lung disease (ILD) is one of the major causes of death in patients with SSc. Exercise tolerance can be investigated by cardio-pulmonary exercise testing (CPET). First-line therapies in patients with SSc associated with ILD (SSc-ILD) include cyclophosphamide and mycophenolate mofetil (MMF). The aim of this study was to evaluate the response of patients with SSc-ILD to MMF by means of CPET. METHODS: Ten consecutive SSc patients were enrolled in this study. All SSc patients underwent clinical evaluation, echocardiography, pulmonary function tests, high-resolution computed tomography (HRCT) and CPET at baseline and after 2 years of therapy with MMF. RESULTS: After 24 months of treatment with MMF (target dose 1500 mg twice daily), forced vitality capacity, diffusing capacity of the lungs for carbon monoxide and systolic pulmonary arterial pressure had not improved significantly and there were no significant differences in HRCT findigns. In addition, peak oxygen uptake (V′O(2) peak) and ventilatory equivalents for carbon dioxide production (V′E/V′CO(2) slope) had not improved significantly. In contrast, there was a significant improvement from baseline to 24 months of treatment in the respiratory exchange ratio [median (interquartile range): 1.07 (0.92–1.22) vs. 1.26 (1.22–1.28), respectively; p < 0.01] and in the Borg scale for leg discomfort [median (interquartile range): 5 (5–7) vs. 4 (3–4), respectively; p < 0.01] . CONCLUSION: These data from our pilot study on a small cohort of SSc patients are the first to demonstrate that treatment with MMF can improves exercise tolerance and leg discomfort in patients with SSc-ILD. These preliminary results need to be confirmed in large randomized studies.