Randomized trial of enteric-coated mycophenolate sodium versus mycophenolate mofetil in multi-system autoimmune disease

BACKGROUND The use of mycophenolate mofetil (MMF) in autoimmune disease is often limited by adverse effects. In this single-centre, open label, parallel design study, we investigated whether enteric-coated mycophenolate sodium (MS) is better tolerated and therefore more efficacious than MMF in primary systemic vasculitis (PSV) and systemic lupus erythematosus (SLE). METHODS Forty patients with vasculitis or systemic lupus erythematosus (SLE) due to commence MMF for active disease or remission maintenance were randomized to receive either 1440 mg/day MS or 2000 mg/day MMF (18 PSV, 2 SLE per group) in addition to corticosteroids. Random allocation was performed by minimization for age, diagnosis and renal function using a computer algorithm. Twenty-five were treated for active disease (5 first-line therapy, 20 salvage therapy) and 15 for remission maintenance. The composite primary end point was treatment failure and/or drug intolerance over 12 months. Treatment failure was defined as failure to achieve remission by 6 months or disease relapse and treatment intolerance was defined as inability to tolerate and maintain the target dose of MS or MMF within 12 months. RESULTS Forty patients were included in the analyses. MS was associated with a lower primary end point rate [hazard ratio (HR) 0.37; 95% CI 0.17-0.80; P = 0.012] (11/20, 55% patients) compared with MMF (17/20, 85% patients). Treatment failure alone was less common in the MS group (HR 0.28; 95% CI 0.095-0.82; P = 0.020), although drug intolerance did not differ between groups (HR 0.53; 95% CI 0.20-1.42; P = 0.21). Despite randomization, patients in the MMF group may have had a higher baseline risk for treatment failure; more MMF patients had refractory disease and granulomatosis with polyangiitis (Wegener's). A glomerular filtration rate (GFR) ≤40 mL/min was associated with intolerance. Serious adverse events were common (55% MMF and 45% MS patients). CONCLUSIONS No differences in treatment tolerance were observed between the MS and MMF groups. Despite similar treatment intolerance, MS was associated with improved efficacy in PSV and SLE compared with MMF. However, baseline group imbalances in factors potentially affecting remission and relapse may have influenced the results. Treatment intolerance was common and strongly associated with low GFR. Further treatment trials are warranted to investigate the effect of GFR on mycophenolic acid pharmacokinetics and clinical outcomes (ISRCTN83027184; EUDRACT 2005-002207-16; Funding Novartis UK).