Remission Induction Therapy with Rituximab for Microscopic Polyangiitis: A Feasibility Study.

Area of Science:

• Nephrology
• Rheumatology
• Immunology

Background:

• Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) encompasses systemic vascular inflammation, with microscopic polyangiitis (MPA) being a prevalent subtype in Japan.
• MPA commonly impacts the kidneys and lungs, posing a significant mortality risk if left untreated.
• Current induction therapy for MPA, often involving methylprednisolone and cyclophosphamide, requires optimization, and the role of rituximab (RTX) in MPA treatment, particularly dosing, remains debated.

Observation:

• This retrospective study evaluated six newly diagnosed MPA patients in Japan treated with methylprednisolone and a single 375 mg/m² dose of RTX.
• Clinical features, efficacy, and safety of this RTX regimen were assessed.
• The study focused on the effectiveness of a single RTX dose, a regimen not extensively studied in Japan for MPA.

Findings:

• All six patients achieved remission within 12 months, with a tapered prednisolone dose below 10 mg/day.
• One patient experienced relapse after 12 months, and another was hospitalized for infective spondyloarthritis.
• No adverse reactions to RTX infusion or late-onset neutropenia were observed, indicating a favorable safety profile.

Implications:

• A single RTX dose demonstrates potential as an effective induction therapy for MPA, facilitating prednisolone dose reduction.
• This regimen offers a promising, potentially cost-effective alternative to multi-dose RTX protocols.
• Further investigation into single-dose RTX for MPA induction therapy is warranted, especially in the Japanese population.