Rituximab as an immunosuppressant in antineutrophil cytoplasmic antibody-associated vasculitis

Rituximab has been used in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) since 2003. Our objective was to describe outcomes and adverse events following rituximab since that time in an inception cohort

Rituximab as an immunosuppressant in antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND: Rituximab has been used in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) since 2003. Our objective was to describe outcomes and adverse events following rituximab since that time in an inception cohort. METHODS: Patients with AAV (diagnosed 1991–2012) who received rituximab (n = 120) were evaluated and incidence per person-year (PPY) with 95% confidence interval was calculated for relapse and infections. Time to remission and relapse by number of rituximab infusions given per treatment course (≤2 versus >2) and by ever having been exposed to cyclophosphamide were compared using Kaplan–Meier curves. Rituximab-treated patients were characterized in comparison with AAV patients treated with cyclophosphamide but not exposed to rituximab (n = 351) using Fisher's exact or rank tests. RESULTS: Rituximab resulted in 86% achieving remission and 41% having a subsequent relapse in a median of 19 months (range 9–29). Time to remission and relapse were similar between rituximab infusion courses (≤2 versus >2; remission P = 0.86 and relapse P = 0.78, respectively). Incidence of relapse was 0.22 PPY (0.14, 0.31) and of severe infection was 0.12 PPY (0.08, 0.24). Time to relapse was shorter in those never exposed to cyclophosphamide (n = 20): 50% by 8 months versus 50% by 24 and 30 months for those with prior or concurrent exposure to cyclophosphamide (n = 100). Compared with those who never received rituximab, rituximab-treated patients were younger (P < 0.001), more likely to have granulomatosis with polyangiitis (P = 0.001) and had more upper airway (P = 0.01) and less kidney involvement (P = 0.007). CONCLUSIONS: Rituximab is beneficial when prescribed outside of a trial setting. Response to treatment and relapse is similar regardless of infusion number. Rituximab without cyclophosphamide may result in a shorter time to relapse supporting combination of these therapies