Rituximab treatment for systemic sclerosis-associated interstitial lung disease: a case series of 13 patients.

Background: Systemic sclerosis (SSc) associated interstitial lung disease (ILD) is a common complication of SSc, with a high mortality, despite current available treatments. Rituximab has shown some promising, although varied, results for the treatment of SSc-ILD.

Aims: To determine whether rituximab stabilised or improved pulmonary function at 12 months, in patients with SSc-ILD.

Methods: A retrospective analysis of patients with SSc-ILD who progressed despite conventional therapy and received rituximab between 2008 and 2019 was performed at two tertiary centres. Baseline percentage forced vital capacity (FVC) and percentage diffusing capacity of carbon monoxide (DLCO) were compared with 1-year post the first dose of rituximab. Mean and median change in FVC (%) and DLCO (%) were calculated. For those with available data, the FVC (%) and DLCO (%) 2 years and 1 year prior to rituximab were compared with the change 12-months post-rituximab.

Results: Thirteen patients were included in the analysis. All patients demonstrated stability in their pulmonary function testing at 1-year post-rituximab. The mean FVC (%) was 57.18 (±16.93 standard deviation (SD)) prior to rituximab and 59.75 (±18.83 SD) 12-month post-rituximab, demonstrating an increase of 2.57 (±4.70 SD; P-value 0.07). The mean DLCO (%) increased from 37.10 (±18.41 SD) prior to rituximab to 38.03 (±19.83) post-rituximab. The mean change in DLCO (%) was 0.93 (±5.05 SD; P-value 0.53). In the 2 years preceding rituximab, the mean FVC (%) and DLCO (%) declined by 9.25 and 9.66 respectively.

Conclusion: This case series suggests that rituximab might stabilise pulmonary function tests, and delay deterioration in patients with progressive SSc-ILD. These findings add to the growing body of evidence suggesting a role for rituximab in the treatment of SSc-ILD.