Relapses and serious adverse events during rituximab maintenance therapy in ANCA-associated vasculitis: a multicentre retrospective study.

ABSTRACT

OBJECTIVES: There are limited real-life data regarding the efficacy and safety of rituximab (RTX) as a remission-maintenance agent in microscopic-polyangiitis (ΜPA) and granulomatosis-with-polyangiitis (GPA). We aimed to estimate the incidence and risk factors for relapses, as well serious-adverse-events (SAEs) in MPA/GPA patients during RTX-maintenance. METHODS: Retrospective cohort of newly-diagnosed/relapsing GPA/MPA patients who received RTX-maintenance (≥1 RTX-cycle, ≥6 months follow-up) following complete-remission (Birmingham-Vasculitis-Activity-Score-version-3 = 0 plus prednisolone ≤7.5 mg/day) with induction regimens. SAEs included serious-infections, COVID-19-associated hospitalizations, deaths, cardiovascular-events, malignancies and hypogammaglobulinemia. Incidence-rates (IR) and relapse-free survival through Kaplan-Meier plots were estimated. Cox-regression was conducted to investigate factors associated with the time-to-relapse. RESULTS: 101 patients were included; 48% females, 69% GPA, 53% newly diagnosed, median age 63 years. During follow-up (294.5 patient-years, median 3 RTX-cycles), 30 relapses (57% major) occurred among 24 patients (24%, IR 10.2/100 patient-years). Kidney involvement (adjusted-Hazard-Ratio/aHR 0.20; 95% CI 0.06-0.74, p= 0.016), prior induction with RTX plus cyclophosphamide (vs RTX monotherapy aHR = 0.02; 95% CI 0.001-0.43, p= 0.012) and shorter time-interval until complete-remission (aHR = 1.07; 95% CI 1.01-1.14, p= 0.023) were associated with decreased relapse-risk. We recorded 17 serious-infections (IR 5.8/100 patient-years), 11 COVID-19-associated hospitalizations (IR 3.7/100 patient-years), 4 malignancies (IR 1.4/100 patient-years), 6 cardiovascular-events (IR 2/100 patient-years) and 10 deaths (IR 3.4/100 patient-years). CONCLUSION: In this real-world study, relapses during RTX-maintenance occurred in approximately in 1 out of 4 patients. Kidney involvement, induction with RTX plus cyclophosphamide and earlier achievement of complete-remission were associated with lower relapse-risk. Serious-infections rate was consistent with previous reports, whereas an increased rate of COVID19-associated hospitalizations was observed.