Rituximab in connective tissue disease-associated interstitial lung disease

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

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.

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.

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.