Genome-wide association study of eosinophilic granulomatosis with polyangiitis reveals genomic loci stratified by ANCA status

Abstract: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare inflammatory disease of unknown cause. 30% of patients have anti-neutrophil cytoplasmic antibodies (ANCA) specific for myeloperoxidase (MPO). Here, we describe a genome-wide association study in 676 EGPA cases and 6809 controls, that identifies 4 EGPA-associated loci through conventional case-control analysis, and 4 additional associations through a conditional false discovery rate approach. Many variants are also associated with asthma and six are associated with eosinophil count in the general population. Through Mendelian randomisation, we show that a primary tendency to eosinophilia contributes to EGPA susceptibility. Stratification by ANCA reveals that EGPA comprises two genetically and clinically distinct syndromes. MPO+ ANCA EGPA is an eosinophilic autoimmune disease sharing certain clinical features and an HLA-DQ association with MPO+ ANCA-associated vasculitis, while ANCA-negative EGPA may instead have a mucosal/barrier dysfunction origin. Four candidate genes are targets of therapies in development, supporting their exploration in EGPA

[Entre deux, la Compagnie Virevolt. Les affranchis, La Flèche. 2007 / photographies de Joël Verhoustraeten]

The treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is based on remission-induction and remission-maintenance. Methotrexate is a widely used immunosuppressant but only a few studies explored its role for maintenance in AAV. This trial investigated the efficacy and safety of methotrexate as maintenance therapy for AAV.In this single-centre, open-label, randomised trial we compared methotrexate and cyclophosphamide for maintenance in AAV. We enrolled patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), the latter with poor-prognosis factors and/or peripheral neuropathy. Remission was induced with cyclophosphamide. At remission, the patients were randomised to receive methotrexate or to continue with cyclophosphamide for 12 months; after treatment, they were followed for another 12 months. The primary end-point was relapse; secondary end-points included renal outcomes and treatment-related toxicity.Of the 94 enrolled patients, 23 were excluded during remission-induction or did not achieve remission; the remaining 71 were randomised to cyclophosphamide (n = 33) or methotrexate (n = 38). Relapse frequencies at months 12 and 24 after randomisation were not different between the two groups (p = 1.00 and 1.00). Relapse-free survival was also comparable (log-rank test p = 0.99). No differences in relapses were detected between the two treatments when GPA+MPA and EGPA were analysed separately. There were no differences in eGFR at months 12 and 24; proteinuria declined significantly (from diagnosis to month 24) only in the cyclophosphamide group (p = 0.0007). No significant differences in adverse event frequencies were observed.MTX may be effective and safe for remission-maintenance in AAV.clinicaltrials.gov NCT00751517

Demographic and clinical characteristics of the patients at study entry.

<p>Demographic and clinical characteristics of the patients at study entry.</p

Adverse events during the planned 24-month follow-up period.

<p>Adverse events during the planned 24-month follow-up period.</p

Subgroup analysis of the Kaplan-Meier estimate of the time from remission to first relapse or death (during the planned 24 month-follow-up) in the cyclophosphamide (CYC) and methotrexate (MTX) groups.

<p>The <i>upper panel</i> shows the analysis in patients with GPA or MPA (granulomatosis with polyangiitis or microscopic polyangiitis) while the <i>lower panel</i> shows the analysis in patients with EGPA (eosinophilic granulomatosis with polyangiitis).</p

Relapse frequencies during the planned 24-month follow-up period.

<p>Relapse frequencies during the planned 24-month follow-up period.</p