Late-onset neutropenia induced by anti-B cell therapy with rituximab in patients with ANCA-associated systemic vasculitis
Authors: Beketova T. V. , Popov I. Yu. , Babak V. V. 
Published: June 2022

In the last decade, anti-neutrophil cytoplasmic antibodies (ANCA)-associated systemic vasculitis (SV) has been treated with the anti-B-cell drug, rituximab (RTM) both for induction and maintenance therapy. One of the problems of the treatment with RTM in patients with ANCA-SV is the risk of late-onset neutropenia (LON), mechanisms of development of which have not been studied enough yet.Objective: to evaluate the incidence and outcomes of LON in patients with ANCA-SV treated with RTM. Patients and methods. A retrospective analysis of the register of 140 patients with ANCA-SV who received RTM treatment at the V.A. Nasonova Research Institute of Rheumatology from 2009 to 2021 years. The median duration of RTM treatment was 49 (6–121) months, the median of the total RTM dose was 3.5 (0.5–9.5) grams. The duration of follow-up exceeded 6 months after the first administration of RTM.Results and discussion. LON was detected in 16 (11.4%) patients, of which 6 suffered from Wegener's granulomatosis with polyangiitis (GPA), 4 – microscopic polyangiitis (MPA), 4 – Churg-Strauss eosinophilic granulomatosis with polyangiitis (EGPA) and 2 – undifferentiated ANCA-SV. In 8 (50%) out of 16 patients, LON developed within 2 months after the 1st course of RTM, in the remaining 8 patients, on average, after 10 (4– 15.5) months. A lethal outcome was documented in 5 (31.2%) of 16 cases of LON (1 with MPA, 3 with GPA, and 1 with EGPA) on average 2 (1.5–9) months after the 1st course of RTM, at the same time, in 4 patients LON was complicated by pneumonia, including 2 with septic shock, in another 1 case LON was combined with the development of acute myocardial infarction and progression of chronic renal failure. Overall mortality among 140 patients with ANCA-SV treated with RTM was 11.4%, while in cases with a fatal outcome, the frequency of LON reached 31.2%.Conclusion. Thus, LON induced by RTM is a common (11%) and clinically significant consequence of B-cell depletion in patients with ANCA-SV, in every 5th case it is complicated by serious infections (including sepsis in 13%) and accounts for a significant proportion in the structure of lethal outcomes (31.2%).Patients treated with RTM require careful monitoring of absolute neutrophil count both during the first months after initiation of anti-B-cell therapy and thereafter. In the combined administration of RTM with cytotoxic drugs (primarily cyclophosphamide) in patients with ANCA-SV, it is necessary to consider the risk of LON developing, secondary immunodeficiency, and infectious complications. During the coronavirus pandemic, one should remember that treatment with interleukin 6 inhibitors used in severe COVID-19 can also be accompanied by neutropenia and requires careful dynamic monitoring of the absolute number of neutrophils in patients with ANCA-SV treated with RTM. It is necessary to inform both patients and physicians of the risk of LON development during the treatment of RTM in ANCA-SV and other rheumatic diseases.