Exploratory Real-World Observations on Pulmonary Function Evolution, HRCT Patterns, and Antifibrotic Escalation in Systemic Sclerosis-Associated Interstitial Lung Disease Treated with Mycophenolate Mofetil

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) remains an important cause of morbidity and mortality in systemic sclerosis. Mycophenolate mofetil (MMF) is widely used as first-line immunosuppressive therapy; however, real-world descriptions of pulmonary functional and radiologic evolution during MMF therapy remain limited, particularly according to high-resolution computed tomography (HRCT) pattern. Objectives: To descriptively evaluate pulmonary function evolution, radiologic findings, and safety outcomes in patients with SSc-ILD treated with MMF in routine clinical practice, with exploratory analyses according to HRCT pattern and subsequent antifibrotic use. Materials and Methods: We conducted a retrospective single-center study including 20 patients with SSc-ILD treated with MMF. Clinical, functional (forced vital capacity [FVC]; diffusing capacity for carbon monoxide [DLCO]), and radiologic (HRCT Warrick score) parameters were assessed at baseline, 6 months, and 12 months. Patients were stratified according to nonspecific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP) patterns. Statistical analyses were exploratory and descriptive. Results: Pulmonary function remained overall stable during follow-up under MMF therapy, while DLCO improvement was observed at 6 months and remained stable at 12 months. Radiologic progression appeared more limited in patients with NSIP pattern, whereas patients with UIP pattern generally exhibited more frequent radiologic progression during follow-up. Patients who subsequently received nintedanib generally presented with UIP-pattern disease, lower baseline DLCO values, and more advanced pulmonary involvement. MMF was generally well tolerated, with treatment discontinuation due to adverse events observed in a single patient. Conclusions: This small retrospective real-world case series describes pulmonary functional and radiologic evolution in patients with SSc-ILD treated with MMF in routine clinical practice. Overall functional stabilization was observed during follow-up, while radiologic progression was more frequently observed in patients with UIP-pattern disease and more advanced baseline pulmonary involvement. Because of the exploratory descriptive design and limited sample size, these observations should be interpreted cautiously and considered hypothesis-generating only. Further prospective studies with standardized radiologic assessment are required.