Mycophenolate Mofetil versus Oral Cyclophosphamide in Scleroderma-related Interstitial Lung Disease: Scleroderma Lung Study II (SLS-II), a double-blind, parallel group, randomised controlled trial

Summary

BACKGROUND

Twelve months of oral cyclophosphamide (CYC) has been shown to alter the progression of scleroderma-related interstitial lung disease (SSc-ILD) when compared to placebo. However, toxicity was a concern and without continued treatment the efficacy disappeared by 24 months. We hypothesized that a two-year course of mycophenolate mofetil (MMF) would be safer, better tolerated and produce longer lasting improvements than CYC.

METHODS

Patients with SSc-ILD meeting defined dyspnea, pulmonary function and high-resolution computed tomography (HRCT) criteria were randomized in a double-blind, two-arm trial at 14 medical centers. MMF (target dose 1500 mg twice daily) was administered for 24 months in one arm and oral CYC (target dose 2·0 mg/kg/day) administered for 12 months followed by placebo for 12 months in the other arm. The primary endpoint, change in forced vital capacity as a percent of the predicted normal value (FVC %) over the course of 24 months, was assessed in a modified intention-to-treat analysis using an inferential joint model combining a mixed effects model for longitudinal outcomes and a survival model to handle non-ignorable missing data. The study was registered with ClinicalTrials.gov, number NCT00883129, and is closed.

RESULTS

Between November, 2009, and January, 2013, 142 patients were randomized. 126 patients (63 MMF; 63 CYC) with acceptable baseline HRCT studies and at least one outcome measure were included in the analysis. The adjusted FVC % (primary endpoint) improved from baseline to 24 months by 2.17 in the MMF arm (95% CI, 0.53–3.84) and 2·86 in the CYC arm (95% confidence interval 1·19–4·58) with no significant between-treatment difference (p=0·24), indicating that the trial was negative for the primary endpoint. However, in a post-hoc analysis of the primary endpoint, within-treatment improvements from baseline to 24 months were noted in both the CYC and MMF arms. A greater number of patients on CYC than on MMF prematurely withdrew from study drug (32 vs 20) and failed treatment (2 vs 0), and the time to stopping treatment was significantly shorter in the CYC arm (p=0·019). Sixteen deaths occurred (11 CYC; 5 MMF) with most due to progressive ILD. Leukopenia (30 vs 4 patients) and thrombocytopenia (4 vs 0 patients) occurred more often in patients treated with CYC. In post-hoc analyses, within- (but not between-) treatment improvements were also noted in defined secondary outcomes including skin score, dyspnea and whole-lung HRCT scores.

INTERPRETATION

Treatment of SSc-ILD with MMF for two years or CYC for one year both resulted in significant improvements in pre-specified measures of lung function, dyspnea, lung imaging, and skin disease over the 2-year course of the study. While MMF was better tolerated and associated with less toxicity, the hypothesis that it would have greater efficacy at 24 months than CYC was not confirmed. These findings support the potential clinical impact of both CYC and MMF for progressive SSc-ILD, as well as the current preference for MMF due to its better tolerability and toxicity profile.

FUNDING

National Heart, Lung and Blood Institute/National Institutes of Health with drug supply provided by Hoffmann-La Roche/Genentech.