Efficacy and Safety of Belimumab and Azathioprine for Maintenance of Remission in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A Randomized Controlled Study.

Abstract

ObjectiveTo evaluate the safety and efficacy of belimumab as adjunctive therapy to maintain remission in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV).MethodsIn this multicenter, double‐blind, placebo‐controlled study, patients with AAV (ages ≥18 years) were randomized 1:1 to receive azathioprine (2 mg/kg/day), low‐dose oral glucocorticoids (≤10 mg/day), and either intravenous belimumab (10 mg/kg) or placebo, following remission induction with rituximab or cyclophosphamide along with glucocorticoids. The primary end point was time to first protocol‐specified event (PSE), with first PSE defined as a Birmingham Vasculitis Activity Score (BVAS) of ≥6, presence of ≥1 major BVAS item, or receipt of prohibited medications for any reason, resulting in treatment failure (adjusted for ANCA type [proteinase 3 (PR3) or myeloperoxidase (MPO)], disease stage at induction, and induction regimen). Vasculitis relapse was defined as the PSE of either a BVAS activity score of ≥6 or receipt of prohibited medications for vasculitis. Changes in treatment practice led to truncation of the study population from ~300 patients to ~100 patients.ResultsThe intent‐to‐treat population totaled 105 patients with AAV, of whom 52 (40 with PR3‐ANCAs, 12 with MPO‐ANCAs) received placebo and 53 (41 with PR3‐ANCAs, 12 with MPO‐ANCAs) received belimumab; 27 of the patients were in rituximab‐induced disease remission, while 78 were in cyclophosphamide‐induced disease remission at baseline. Compared with placebo, treatment with belimumab did not reduce the risk of a PSE (adjusted hazard ratio [HR] 1.07, 95% confidence interval [95% CI] 0.44–2.59; P = 0.884) or vasculitis relapse (adjusted HR 0.88, 95% CI 0.29–2.65; P = 0.821). The overall rate of PSEs was low (11 [21.2%] of 52 patients receiving placebo, 10 [18.9%] of 53 patients receiving belimumab). Vasculitis relapse in the placebo group (n = 8) occurred independent of the induction regimen, disease stage, or ANCA type. All vasculitis relapses in the belimumab group (n = 6) occurred in patients who had PR3‐ANCA–associated vasculitis with cyclophosphamide‐induced disease remission. Adverse events occurred in 49 (92.5%) of 53 patients receiving belimumab and 43 (82.7%) of 52 patients receiving placebo, with no new safety concerns.ConclusionBelimumab plus azathioprine and glucocorticoids for the maintenance of remission in AAV did not reduce the risk of relapse.