Enteric-coated Mycophenolate Sodium therApy versus cyclophosphamide for induction of Remission in Microscopic PolyAngiitis (EMSAR-MPA trial): study protocol for a randomised controlled trial.

INTRODUCTION: Several studies have demonstrated that mycophenolate mofetil (MMF) may be an excellent alternative to cyclophosphamide (CYC) or rituximab for the induction of remission in non-life-threatening anti-neutrophil cytoplasmic antibodies associated vasculitis because of its strong immunosuppressive potency and low toxicity profile. Enteric-coated mycophenolate sodium (EC-MPS) was introduced to reduce gastrointestinal adverse reactions of MMF. This study will evaluate the efficacy and safety of EC-MPS combined with glucocorticoid in patients with active and non-life-threatening microscopic polyangiitis (MPA).

METHODS AND ANALYSIS: This study is a multicentre, open-label, randomised controlled, non-inferiority trial. A total of 110 patients with active and non-life-threatening MPA from 11 hospitals in Shanxi Province of China will be recruited and randomised in a 1:1 ratio to receive either EC-MPS or CYC. All patients will receive the same glucocorticoid plan. We will compare oral EC-MPS (720-1440 mg/day) with intravenous pulsed CYC (7.5-15 mg/kg) administered for 3-6 months. All patients will be switched from their assigned treatment (EC-MPS or CYC) to oral azathioprine (2 mg/kg/day) after remission has been achieved, between 3 and 6 months. Azathioprine will be continued until the study ends at 18 months. The primary end point of efficacy is the remission rate at 6 months. Follow-up will continue for 18 months in order to detect an influence of induction regimen on subsequent relapse rates.

ETHICS AND DISSEMINATION: This study has received approval from the Ethics Committee of the Second Hospital of Shanxi Medical University (2022YX-026). All participants are required to provide written informed consent and no study-related procedures will be performed until consent is obtained. The results of this trial will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER: ChiCTR2200063823.