Treatment of ANCA-Associated Vasculitis

Remission Induction and Maintenance

The American College of Rheumatology recommends treating remission induction of organ-threatening or life-threatening AAV with glucocorticoids combined with EITHER cyclophosphamide OR rituximab (Level 1 evidence, Grade A recommendation for GPA/MPA) 3, 4
Rituximab is particularly preferred over cyclophosphamide in patients with relapsing disease, women of childbearing age, or when cyclophosphamide poses specific risks 5
Cyclophosphamide causes reduced ovarian reserve, ovarian failure, and male infertility, whereas rituximab has no reported fertility concerns 1, 2, 5
The standard rituximab induction regimen is 375 mg/m² IV weekly for 4 weeks, combined with high-dose glucocorticoids 5
For maintenance therapy, rituximab is superior to azathioprine and should be preferred whenever possible 5
The MAINRITSAN trial demonstrated that rituximab (500 mg every 6 months) resulted in major relapses in only 3 patients versus 17 with azathioprine at month 28 (hazard ratio 6.61, P=0.002) 3
The recommended maintenance regimen is rituximab 500 mg IV every 6 months for at least 18 months 5, 6

Pneumocystis jirovecii prophylaxis with trimethoprim/sulfamethoxazole is required during rituximab therapy 1, 2, 5
Monitor immunoglobulin levels every 6 months during rituximab therapy, as hypogammaglobulinemia occurs in 27-58% of patients 5
Do not use ANCA titers to guide treatment changes; use structured clinical assessment instead (Level 4 evidence, Grade D recommendation) 4, 5

For patients refractory to initial therapy after 4 weeks or with <50% reduction in disease activity score after 6 weeks, switch from cyclophosphamide to rituximab or vice versa (Level 3 evidence, Grade C recommendation) 3, 4
Patients with PR3-ANCA positivity have increased relapse risk and may benefit from extended maintenance therapy duration 3