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Objective: To compare rituximab‐ versus cyclophosphamide‐based remission induction strategies for the long‐term risks of kidney failure and death in antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis (AAV) in a real‐world cohort. Methods: We performed a cohort study using the Mass General Brigham AAV Cohort, which includes proteinase 3–ANCA+ and myeloperoxidase (MPO)‐ANCA+ AAV patients diagnosed from January 1, 2002 to December 31, 2019. We included cases in which the initial remission induction strategy was based either on rituximab or cyclophosphamide. The primary outcome was the composite outcome of kidney failure or death. We used multivariable Cox proportional hazards models and propensity score–matched analyses to assess the association of rituximab‐ versus cyclophosphamide‐based treatment strategies with the composite outcome of kidney failure or death. Results: Of 595 included patients, 352 patients (~60%) received rituximab‐based and 243 patients (~40%) received cyclophosphamide‐based regimens. The mean age was 61 years, 58% of patients were female, 70% of patients were MPO‐ANCA+, and 69% of patients had renal involvement (median estimated glomerular filtration rate 37.3 ml/minute/1.73 m2). There were 133 events at 5 years, and the incidence rates in rituximab‐ and cyclophosphamide‐based regimens were 6.8 and 6.1 per 100 person‐years, respectively. The risk of kidney failure or death was similar in both groups in multivariable‐adjusted analyses (hazard ratio [HR] 1.03 [95% confidence interval (95% CI) 0.55–1.93]) and in propensity score–matched analyses (HR 1.05 [95% CI 0.55–1.99]) at 5 years. Our findings were similar when outcomes were assessed at 1 and 2 years as well as in subgroups stratified according to renal involvement and severity as well as major organ involvement. Conclusion: Rituximab‐ and cyclophosphamide‐based remission induction strategies for AAV are associated with similar risks of kidney failure and death. [ABSTRACT FROM AUTHOR]

Objective: Proteinase 3 (PR3) is the major antigen for antineutrophil cytoplasmic antibodies (ANCAs) in the systemic autoimmune vasculitis, granulomatosis with polyangiitis (GPA). PR3‐targeting ANCAs (PR3‐ANCAs) recognize different epitopes on PR3. This study was undertaken to study the effect of mutations on PR3 antigenicity. Methods: The recombinant PR3 variants, iPR3 (clinically used to detect PR3‐ANCAs) and iHm5 (containing 3 point mutations in epitopes 1 and 5 generated for epitope mapping studies) immunoassays and serum samples from patients enrolled in ANCA‐associated vasculitis (AAV) trials were used to screen for differential PR3‐ANCA binding. A patient‐derived monoclonal ANCA 518 (moANCA518) that selectively binds to iHm5 within the mutation‐free epitope 3 and is distant from the point mutations of iHm5 was used as a gauge for remote epitope activation. Selective binding was determined using inhibition experiments. Results: Rather than reduced binding of PR3‐ANCAs to iHm5, we found substantially increased binding of the majority of PR3‐ANCAs to iHm5 compared to iPR3. This differential binding of PR3‐ANCA to iHm5 is similar to the selective moANCA518 binding to iHm5. Binding of iPR3 to monoclonal antibody MCPR3‐2 also induced recognition by moANCA518. Conclusion: The preferential binding of PR3‐ANCAs from patients, such as the selective binding of moANCA518 to iHm5, is conferred by increased antigenicity of epitope 3 on iHm5. This can also be induced on iPR3 when captured by monoclonal antibody MCPR2. This previously unrecognized characteristic of PR3‐ANCA interactions with its target antigen has implications for studying antibody‐mediated autoimmune diseases, understanding variable performance characteristics of immunoassays, and design of potential novel treatment approaches. [ABSTRACT FROM AUTHOR]

Objective: Autoreactive B cells are responsible for antineutrophil cytoplasmic antibody (ANCA) production in ANCA‐associated vasculitis (AAV). Rituximab (RTX) depletes circulating B cells, including autoreactive B cells. We aimed to evaluate changes and associations with relapse of the circulating autoreactive B cell pool following therapeutic B cell depletion in AAV. Methods: Sequential flow cytometry was performed on 148 samples of peripheral blood mononuclear cells from 23 patients with proteinase 3 (PR3)–ANCA–positive AAV who were treated with RTX for remission induction and monitored after stopping therapy during long‐term follow‐up in a prospective clinical trial. PR3 was used as a ligand to target autoreactive PR3‐specific (PR3+) B cells. B cell recurrence was considered as the first blood sample with ≥10 B cells/μl after RTX treatment. Results: At B cell recurrence, PR3+ B cell frequency among B cells was higher than baseline (P < 0.01). Within both PR3+ and total B cells, frequencies of transitional and naive subsets were higher at B cell recurrence than at baseline, while memory subsets were lower (P < 0.001 for all comparisons). At B cell recurrence, frequencies of B cells and subsets did not differ between patients who experienced relapse and patients who remained in remission. In contrast, the plasmablast frequency within the PR3+ B cell pool was higher in patients who experienced relapse and associated with a shorter time to relapse. Frequencies of PR3+ plasmablasts higher than baseline were more likely to be found in patients who experienced relapse within the following 12 months compared to those in sustained remission (P < 0.05). Conclusion: The composition of the autoreactive B cell pool varies significantly following RTX treatment in AAV, and early plasmablast enrichment within the autoreactive pool is associated with future relapses. [ABSTRACT FROM AUTHOR]

Objective: To study the longitudinal effects of both glucocorticoids and tocilizumab, an interleukin‐6 receptor inhibitor, on hemoglobin A1c (HbA1c) levels during glucocorticoid tapering. Methods: We analyzed patients with complete data from the Giant Cell Arteritis Clinical Research Study (GiACTA) to investigate the impact of both glycemic and nonglycemic factors on changes in HbA1c levels over the 52‐week trial. Giant cell arteritis (GCA) patients were randomized to receive either tocilizumab or placebo in addition to glucocorticoids. We used a multivariable mixed‐effects model to evaluate associations of HbA1c level with daily glucocorticoid dose, randomization to receive tocilizumab, and red blood cell count in patients with and those without diabetes mellitus at baseline, over 52 weeks. Results: In 209 patients, the median HbA1c level decreased by 0.50% (P < 0.01) in the group that received both tocilizumab and glucocorticoids (tocilizumab/glucocorticoid) and by 0.10% (P < 0.01) in the glucocorticoid‐only group. Randomization to tocilizumab/glucocorticoid was associated with lower HbA1c (β = −0.209% in those without diabetes, P < 0.01; β = −0.290% in those with diabetes, P = 0.23). These changes had a sizable impact on glucose tolerance classification: 42.5% of patients in the tocilizumab/glucocorticoid group improved from prediabetes status to normal, compared to only 12.5% of patients treated with glucocorticoids alone. Daily glucocorticoid dose was associated with HbA1c level in patients with baseline diabetes (β = 0.018%/mg, P < 0.01) and those without baseline diabetes (β = 0.005%/mg, P < 0.01). Conclusion: Tocilizumab treatment was associated with a substantial reduction in HbA1c level, independent of glucocorticoid exposure, which may be achieved through a combination of glycemic and nonglycemic effects. [ABSTRACT FROM AUTHOR]

Objective: To assess the frequency of venous thromboembolism (VTE) events in the Rituximab in Antineutrophil Cytoplasmic Antibody (ANCA)–Associated Vasculitis (RAVE) trial and identify novel potential risk factors. Methods: VTE events in 197 patients enrolled in the RAVE trial were analyzed. Baseline demographic and clinical characteristics were recorded, and univariate and multivariate analyses were performed to identify factors associated with VTE in ANCA‐associated vasculitis (AAV). Results: VTE occurred in 16 patients (8.1%) with an overall average time to event of 1.5 months (range 1.0–2.75). In univariate analyses with calculation of hazard ratios (HRs) and 95% confidence intervals (95% CIs), heart involvement (HR 17.408 [95% CI 2.247–134.842]; P = 0.006), positive proteinase 3 (PR3)–ANCA (HR 7.731 [95% CI 1.021–58.545]; P = 0.048), pulmonary hemorrhage (HR 3.889 [95% CI 1.448–10.448]; P = 0.008), and the presence of red blood cell casts (HR 15.617 [95% CI 3.491–69.854]; P < 0.001) were associated with the onset of VTE. In multivariate models adjusted for age and sex, the significant associations between VTE events and heart involvement (HR 21.836 [95% CI 2.566–185.805]; P = 0.005), PR3‐ANCA (HR 9.12 [95% CI 1.158–71.839]; P = 0.036), pulmonary hemorrhage (HR 3.91 [95% CI 1.453–10.522]; P = 0.007), and urinary red blood cell casts (HR 16.455 [95% CI 3.607–75.075]; P < 0.001) remained. Conclusion: Patients diagnosed as having AAV with pulmonary hemorrhage, positive PR3‐ANCA, heart involvement, and the presence of red blood cell casts are at an increased risk to develop VTE. Further studies are needed to confirm and expand these findings and to explore the mechanisms of hypercoagulability in these patients with the aim of informing potential targets for therapeutic intervention. [ABSTRACT FROM AUTHOR]

Objective: To evaluate circulating cytokine profiles in patients with antineutrophil cytoplasmic antibody–associated vasculitis (AAV), classified by antineutrophil cytoplasmic antibody (ANCA) specificity (proteinase 3 ANCA [PR3‐ANCA] versus myeloperoxidase ANCA [MPO‐ANCA]) or by clinical diagnosis (granulomatosis with polyangiitis [GPA] versus microscopic polyangiitis [MPA]). Methods: A panel of 29 cytokines was tested in 186 patients with active AAV at inclusion into the Rituximab in AAV trial. Cytokine concentrations were compared between groups within each classification system. Multivariable analyses adjusted for age, sex, and renal insufficiency were performed, with each biomarker as a dependent variable and ANCA specificity and clinical diagnosis as explanatory variables of interest. Results: Levels of 9 circulating cytokines (interleukin‐6 [IL‐6], granulocyte–macrophage colony‐stimulating factor [GM‐CSF], IL‐15, IL‐18, CXCL8/IL‐8, CCL‐17/thymus and activation–regulated chemokine [TARC], IL‐18 binding protein [IL‐18 BP], soluble IL‐2 receptor α [sIL‐2Rα], and nerve growth factor β [NGFβ]) were significantly higher in PR3‐AAV than MPO‐AAV, 4 cytokines (sIL6R, soluble tumor necrosis factor receptor type II [sTNFRII], neutrophil gelatinase–associated lipocalin [NGAL], and soluble intercellular adhesion molecule 1 [sICAM‐1]) were higher in MPO‐AAV than in PR3‐AAV, 6 cytokines (IL‐6, GM‐CSF, IL‐15, IL‐18, sIL‐2Rα, and NGFβ) were higher in GPA than in MPA, and 3 cytokines (osteopontin, sTNFRII, and NGAL) were higher in MPA than in GPA (all P < 0.05). For nearly all cytokines, the difference between PR3‐AAV and MPO‐AAV was larger than that between GPA and MPA. The multivariate analysis showed that 8 cytokines (IL‐15, IL‐8, IL‐18 BP, NGF‐β, sICAM‐1, TARC, osteopontin, and kidney injury molecule 1 (P < 0.05) distinguished patients with AAV better (lower P values and larger effect sizes) when grouped by ANCA specificity than by clinical diagnosis. Conclusion: Distinct cytokine profiles were identified for PR3‐AAV versus MPO‐AAV and for GPA versus MPA. Differences in these circulating immune mediators are more strongly associated with ANCA specificity than with clinical diagnosis, suggesting that heterogeneity in the AAV subtypes extends beyond clinical phenotypes. [ABSTRACT FROM AUTHOR]

Objective Relapse following remission is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), particularly with ANCAs directed at proteinase 3 (PR3). This study was undertaken to evaluate the association of an increase in PR3-ANCA level with subsequent relapse. Methods Data from the Rituximab versus Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. Starting from the time of achieving complete remission, serial measurements by direct and capture enzyme-linked immunosorbent assays (ELISAs) were analyzed in 93 patients with PR3-ANCA, using Cox proportional hazards regression. Results An increase in PR3-ANCA level was identified in 58 of 93 subjects (62.4%) by direct ELISA and in 59 of 93 (63.4%) by capture ELISA. Relapses occurred in 55 of 93 subjects (59.1%), with 25 and 21 occurring within 1 year after an increase by direct ELISA and capture ELISA, respectively. An increase by direct ELISA was associated with subsequent severe relapses (hazard ratio [HR] 4.57; P < 0.001), particularly in patients presenting with renal involvement (HR 7.94; P < 0.001) and alveolar hemorrhage (HR 24.19; P < 0.001). Both assays identified increased risk for severe relapse in the rituximab group (HR 5.80; P = 0.002 for direct ELISA and HR 4.54; P = 0.007 for capture ELISA) but not the cyclophosphamide/azathioprine group ( P = 0.103 and P = 0.197, respectively). Conclusion The association of an increase in PR3-ANCA level with the risk of subsequent relapse is partially affected by the PR3-ANCA detection methodology, disease phenotype, and remission induction treatment. An increase in PR3-ANCA level during complete remission conveys an increased risk of relapse, particularly severe relapse, among patients with renal involvement or alveolar hemorrhage and those treated with rituximab. Serial measurements of PR3-ANCA may be informative in this subset of patients, but the risk of relapse must be weighed carefully against the risks associated with therapy. [ABSTRACT FROM AUTHOR]

Objective. IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory condition that can affect nearly any organ. Prior studies have focused on individual cases of IgG4-RD or small case series. This study was undertaken to report detailed clinical and laboratory findings in a larger group of patients with IgG4-RD whose diagnosis was established by strict clinicopathologic correlation. Methods. The baseline features of 125 patients with biopsy-proven IgG4-RD were reviewed. The diagnosis was confirmed by pathologists' review, based on consensus diagnostic criteria and correlation with clinicopathologic features. Disease activity and damage were assessed using the IgG4-RD Responder Index (RI). Flow cytometry was used to assess levels of circulating plasmablasts. Results. Of the 125 patients, 107 had active disease and 86 were not receiving treatment for IgG4-RD. Only 51% of the patients with active disease had elevated serum IgG4 concentrations. However, patients with active disease and elevated serum IgG4 concentrations were older, had a higher IgG4-RD RI score, a greater number of organs involved, lower complement levels, higher absolute eosinophil counts, and higher IgE levels compared to those with active disease but normal serum IgG4 concentrations (P < 0.01 for all comparisons). The correlation between IgG41 plasmablast levels and the IgG4-RD RI of disease activity (Spearman's r50.45, P50.003) was stronger than the correlation between total plasmablast levels and the IgG4-RD RI. Seventy-six (61%) of the patients were male, but no significant differences according to sex were observed with regard to disease severity, organ involvement, or serum IgG4 concentrations. Treatment with glucocorticoids failed to produce sustained remission in 77% of patients. Conclusion. Nearly 50% of this patient cohort with biopsy-proven, clinically active IgG4-RD had normal serum IgG4 concentrations. Elevations in the serum IgG4 concentration appeared to identify a subset of patients with a more severe disease phenotype. In addition, the levels of IgG41 plasmablasts correlated well with the extent of disease activity. [ABSTRACT FROM AUTHOR]