Rituximab in connective tissue disease-associated interstitial lung disease.

Introduction/objectives: To evaluate rituximab (RTX) effectiveness and safety in patients with interstitial lung disease (ILD) related to connective tissue diseases (CTD).

Methods: Retrospective multicenter cohort study, including patients with CTD-ILD, followed in six Portuguese rheumatology departments until November 2018. ILD diagnosis was based on high-resolution CT (HRCT) and/or lung biopsy. Results of HRCT, pulmonary function tests, and 6-min walking test before and after RTX were compared using the Wilcoxon matched pair test. Safety, including adverse events during treatment and reasons for RTX discontinuation, was also analyzed.

Results: A total of 49 patients were included, with rheumatoid arthritis being the commonest CTD (61.2%). The median interval between CTD onset and ILD diagnosis was 4 years (IQR 1-9.5) and median ILD duration at first RTX administration was 1 year (IQR 0-4). The median RTX treatment duration until the last follow-up was 3 years (IQR 1-6). Usual interstitial pneumonia (UIP) and non-specific interstitial pneumonia (NSIP) were the commonest patterns, occurring in 20 and 18 patients, respectively. One year after RTX first administration, there was a stabilization in carbon monoxide diffusing capacity (DLCO; mean + 5.4%, p = 0.12) and improvement in forced vital capacity (FVC; mean + 4.3%, p = 0.03), particularly in patients with NSIP. Patients with UIP had less promising results, but at 1 year, pulmonary function tests remained stable (DLCO + 2.5%, p = 0.77; FVC + 4.2%, p = 0.16). Infection was the main reason for RTX discontinuation and led to two deaths.

Conclusions: RTX seems to be a promising treatment for CTD-ILD patients, particularly when NSIP pattern is present. Key points • The use of rituximab in patients with interstitial lung disease related to connective tissue disease is associated with long-standing disease stability in a wide range of systemic rheumatic diseases. • Efficacy results were particularly impressive in patients with non-specific interstitial pneumonia pattern, although in a subgroup of patients with usual interstitial pneumonia pattern, disease progression was also hold with this treatment. • In a large number of patients, rituximab was used in monotherapy and as first-line treatment.