Background/Purpose: Interstitial lung disease (ILD) associated with inflammatory myopathy (IM) has a poor prognosis and requires specific treatments. Intravenous Cyclophosphamide (CYC) is one of the main treatments for moderate to severe ILD in Europe. Recent data suggested that Rituximab (RTX) could also be effective in this context. We thus retrospectively compared the efficacy of CYC followed by classical immunosuppressive treatment (IST) vs. RTX in inflammatory myopathy-related ILD.

Methods: Between 2003-15, 43 patients with IM-related ILD were included either at diagnosis or during a relapse. Pulmonary progression was defined in accordance with the American Thoracic Society (ATS), including NYHA stage progression, any severe event related to the ILD, CT-scan worsening and/or pulmonary function test aggravation (FVC > 10% and DLCO > 15% decrease). Serious adverse events were recorded in both groups. Uni- and multivariate statistical analyses were performed using appropriate tests.

Results: Steroids were given to all patients and cumulative doses were similar in both groups. Twenty-eight patients received intravenous CYC (6 monthly pulses [2-12], 700mg/m2), always followed by classical IST, including azathioprine (n = 14) or mycophenolate mofetil (n = 5). Fifteen patients were included in the RTX group and received two pulses initially (1g, D1-D15); infusions were repeated every 6 months (1g, median = 2 times [1-3]). Only six patients (40%) received concomitant classical IST. Median FCV at enrolment was 55% [29-113] in CYC group vs. 71% [45-96] in the RTX group (p = 0.01) and median DLCO was 30% [15-66] in CYC group vs. 42% [21-88] in RTX group (p = 0.03). After two year, median FVC increased by 38% (p = 0.02) and median DLCO increased by 32% (p = 0.08) in the CYC group as compared to 31% (p = 0.002) and 0% (p = 0.84) in the RTX group, respectively. However, ILD progression occurred in 11 patients (39%) after two years as compared to 2 patients (13%) in the RTX group. Whereas it was similar after 6 months in both groups, the survival without pulmonary progression showed a significant advantage for RTX group at two years (p = 0.023). Multivariate analysis showed that a ≥15% DLCO decrease at six months was the only criterion predicting the pulmonary progression at two years (p = 0.03). Nine patients (32%) had serious adverse events (mostly infectious complications) in CYC group, as compared to one (7%) in the RXT group (p = 0.07).

Conclusion: Patients receiving RTX for IM-related ILD showed a better survival without pulmonary progression than those treated with CYC followed by conventional IST. The difference was more significant during the “maintenance therapy period”. RTX seemed also better tolerated than CYC. The place of RTX in this context should thus be reconsidered and validated prospectively.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/intravenous-cyclophosphamide-followed-by-oral-immunosuppressive-treatment-versus-rituximab-in-inflammatory-myopathy-related-interstitial-lung-disease/