ABSTRACT
Background: Rituximab (RTX) achieved high remission-induction and sustained maintenance rates for patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) [1], [2]. However, RTX is an expensive medication, which may potentially lead to serious side effects. Defning the best dose regimen for maintenance in AAV is still an unmet need. Objectives: The aim of the present study is to compare the effects of ultra-low dose RTX (500 mg or 1000 mg once per year) to standard low dose RTX (500 or 1000 mg twice per year) as remission-maintenance therapy in AAV patients. Methods: We included consecutive AAV patients (classifed as GPA and MPA [3]) referring to four different Rheumatology centers in Italy. We assessed all AAV patients who successfully achieved disease remission (BVASv3=0) with conventional RTX or cyclophosphamide regimens and have been subsequently treated with RTX for maintenance of remission. All included patients received at least three maintenance infusions with either 1000 mg or 500 mg, twice per year (standard low dose) or once per year (ultra-low dose). After a period of 18 months, we assessed the remission rate, damage (VDI), glucocorticoids intake, ANCA status, B-cells depletion and serum IgG levels. Results: From January 2011 to December 2021, 83 AAV patients (mean age 51±16, 49.4% female, 95.2% ANCA positive, 65.8% anti PR3, 34.2% anti MPO), 61 classifed as GPA and 22 MPA, achieved complete disease remission with conventional RTX induction regimen. After 7 [6-9] months, 29.9% patients started maintenance treatment with ultra-low dose RTX (once per year), while 70.1% patients with standard low dose (twice per year), for 18 months. No signifcant differences at baseline were noted between patients receiving ultra-low dose when compared to those treated with conventional low-dose. At the end of observation period, a disease fare was observed in 22.7% of the low-dose group, and 21.2% in those treated with the standard dose (p=0.881). Relapse-free survival was comparable between the two group (log-rank p=0.818, Figure 1). When comparing AAV patients treated with ultra-low dose regimen to those treated with low-dose, no differences were noted in negative ANCA rate (72.2% vs 67.1%, p=0.262), ANCA titer (0 [0-7.8] vs 0 [0-50] UI/mL, p=0.232), B-cells depletion rate (70.6% vs 75%, p=0.725), mean serum IgG (811 [146-922] vs 680 [429-861] mg/dL, p=0.367), mean daily glucocorticoid dosage (2.5 [0-5] vs 3.75 [0-5] mg/d, p=0.647), VDI (4 [1-5] vs 2 [1-4], p=0.098), hypogammaglobulinaemia rate (31.8% vs 36.5%, p=0.697) and deaths (4.5% vs 5.8%, p=0.831). Although not signifcant, patients treated with ultra-low dose had lower severe infection rate (10.5% vs 26.8%, p=0.154). Notably, in the all cohort 5 deaths were related to COVID19 pneumonia. Conclusion: Reduced exposure to RTX was not associated with an impaired efficacy of maintenance therapy in patients with AAV. Remission maintenance with ultra-low dose RTX is a safe and more cost-effective option.