Tailoring Maintenance Therapy to Cluster of Differentiation 5 Positive (CD5+) Regulatory B Cell Recovery in ANCA Vasculitis

Overview

ANCA vasculitis is a pauci-immune systemic small vessel vasculitis. The anti-neutrophilic cytoplasmic antibodies (ANCA) are pathogenic and cause disease by activating neutrophils which damage blood vessels. CD means "cluster of differentiation" . CD5 is a type I transmembrane protein found on T cells, thymocytes, and some B cells. Cluster of Differentiation 20 (CD20) is a type III transmembrane protein found on B cells. The investigators previously detected an association between recovery of Interleukin 10 (IL-10)-secreting CD20+ and CD5+ regulatory B cells after immunotherapy (with rituximab and corticosteroids) and decreased risk of subsequent relapse in patients with ANCA-vasculitis. The investigators hypothesize that patients with complete reconstitution of a functional regulatory B cell repertoire after induction therapy are at low risk of relapse and may be monitored conservatively without further immunotherapy. The investigators will test this hypothesis through a proof of concept randomized controlled study. Patients with normalization of CD5+ regulatory B cells will be randomized to maintenance therapy with rituximab vs. close observation without immunosuppression. Patients whose peripheral CD5+ regulatory B cells remain low after induction therapy (who are at higher risk of relapse), will receive maintenance immunosuppression with rituximab. Patients needing or randomized to maintenance therapy who are unable to receive rituximab will receive azathioprine or mycophenolate mofetil, two standard alternative medications for maintenance immunosuppression.

The goal of this study is to test the hypothesis that, in ANCA vasculitis, use of CD5+ B cells at the time of B cell reconstitution in the peripheral blood can be used to stratify patients between those with low % CD5+ B cells at greater risk of relapse who would need maintenance immunosuppression and those with normalized CD5+ B cells who would be at lower risk of relapse, and therefore may not need maintenance immunosuppression. The latter group will be randomized to either maintenance immunosuppression vs close clinical observation without maintenance immunosuppression. This study is not designed to evaluate the efficacy of new therapies in ANCA vasculitis. The treatment regimen used in the proposed study are routinely used in the treatment of patients with ANCA vasculitis and considered standard-of-care.