Patrick H. Nachman

Predictors of Relapse and Treatment Resistance in Antineutrophil Cytoplasmic Antibody–Associated Small-Vessel Vasculitis

Context Patients with antineutrophil cytoplasmic autoantibody (ANCA)associated small-vessel vasculitis sometimes experience relapses and resistance to glucocorticoid and cyclophosphamide treatment. Contribution This study followed 350 patients with ANCA-associated vasculitis for a median of 49 months. Of 258 patients attaining remission, 109 (42%) relapsed. Upper or lower respiratory tract disease and proteinase-3 ANCA seropositivity were associated with increased risk for relapse. Of 334 treated patients, 77 (23%) had progressive disease despite treatment. Severe kidney disease, black ethnicity, and female sex were associated with an increased risk for treatment resistance. Cautions The participants were primarily selected on the basis of their condition being identified by renal biopsy. The Editors Antineutrophil cytoplasmic antibody (ANCA)associated small-vessel vasculitis includes microscopic polyangiitis, Wegener granulomatosis, the ChurgStrauss syndrome, and renal-limited vasculitis (ANCA-associated glomerulonephritis) (1, 2). The cornerstone of treatment for ANCA-associated vasculitis includes induction therapy with pulse corticosteroids and the prompt institution of daily oral glucocorticoids and cyclophosphamide (3-6). Approximately 85% of patients achieve remission with this therapy (5), but 11% to 57% of patients have a relapse (7-11). Some relapses are severe, resulting in worsening end-organ damage. Most relapses respond to therapy, but patients are subjected to additional immunosuppressive or cytotoxic drugs. Fear of relapsing disease has impelled physicians to prescribe prolonged maintenance therapies in most patients. Because 43% to 89% of patients may never have a disease relapse (7-11), use of long-term immunomodulating therapy often presents unnecessary risks and may well outweigh the benefits of preventing relapse. Little is known regarding predictors for relapse; identification of these risk factors would conceivably allow maintenance immunomodulatory therapy to be tailored to patients at high risk while sparing others unnecessary exposure to these drugs. Over the course of almost 2 decades, we recruited a large cohort of patients with ANCA-associated glomerulonephritis and vasculitis. From this sample, we sought to ascertain the following: Which patients were more likely to be resistant to treatment; which patients were more likely to progress to end-stage kidney disease; the potential to determine which patients were more likely to relapse; the impact of relapse on long-term outcome; the correlation between length of immunosuppressive therapy and the likelihood of relapse; and the viability of discontinuing immunosuppressive therapy in patients who have attained remission. Methods Patient Sample and Definitions Patients were eligible for this study if they had biopsy-proven vasculitis (diagnosed between 1985 and 2003) with positive ANCA determination by immunofluorescence microscopy or antigen-specific enzyme-linked immunosorbent assay (12); the patients were also required to be followed by physicians of the Glomerular Disease Collaborative Network (GDCN). The GDCN and a subset of the cohort were previously described elsewhere (4, 7), but the cohort was expanded to evaluate predictors of relapse. We used the University of North Carolina (UNC) Nephropathology Laboratory, which evaluates more than 1500 renal biopsies each year, to recruit participants for the GDCNs registry of patients with ANCA-associated vasculitis. All patients with a native kidney biopsy diagnosis of pauci-immune necrotizing and crescentic glomerulonephritis with or without granulomatous inflammation were eligible to enroll in the registry (n= 639). Patients were invited to give informed consent to participate through their treating nephrologist. We then collected medical records dating back to the initial diagnosis of ANCA-associated vasculitis. A total of 307 patients (48% of eligible participants) with a biopsy-proven diagnosis were enrolled in this study. An additional 59 (9%) patients signed consent to participate but were deemed ineligible because of negative ANCA test results or overlapping disease. Another 43 patients who had not undergone renal biopsy were recruited through the multidisciplinary UNC Vasculitis Clinic and through other GDCN nephrologists who work in collaboration with other medical specialists to care for patients with ANCA-associated vasculitis. Estimates of potentially eligible patients without a kidney biopsyproven diagnosis were not available because no centralized service exists to evaluate nonrenal biopsy tissue. Initial biopsy diagnosis, whatever the organ, was used as each patients start date in the registry. Detailed information on duration of symptoms before biopsy diagnosis was not always described in medical records and therefore was not available for analysis in this study. The Committee on the Protection of Human Subjects at UNC approved this study. Patients in the cohort received clinically indicated care from their primary nephrologists, who were affiliated with 63 different GDCN private practice offices (1 to 12 nephrologists per office) and 5 academic medical centers, including UNC. Therapeutic interventions and frequency of clinical evaluations were not determined by protocol. Physicians were instructed to update GDCN records for patients on a yearly basis; follow-up calls and written reminders were provided if information was not received. Consequently, patient follow-up did not vary substantially across clinics. Patients were categorized as having cytoplasmic ANCA, antiproteinase-3 (anti-PR3) ANCA, or both, or perinuclear ANCA, anti-myeloperoxidase (anti-MPO) ANCA, or both. Patients having only perinuclear ANCA were required to have a negative antinuclear antibody test. Categories of ANCA-associated vasculitis included Wegener granulomatosis, microscopic polyangiitis, and renal-limited disease (1, 2). The single patient with the ChurgStrauss syndrome was included with the microscopic polyangiitis group. Organ involvement was determined by biopsy or by previously described criteria (4, 7). For example, lung involvement was considered likely in the presence of hemoptysis; pulmonary hemorrhage; respiratory failure; or radiographic proof of infiltrates, nodules, or cavities without evidence of infection. Upper respiratory tract disease was considered likely with clinical or radiographic studies revealing sinusitis, otitis media, nasal crusting, or subglottic disease. Treatment categories were determined by the first therapy regimen used at diagnosis (corticosteroids alone or in combination with cyclophosphamide, as previously described) (3). In brief, induction therapy was typically initiated with 3 daily pulses of methylprednisolone (7 mg/kg of body weight per day) followed by daily oral prednisone. Prednisone therapy was started at a dose of 1 mg/kg per day for the first month and was tapered over 3 to 4 months. Cyclophosphamide was administered by intravenous pulse (0.5 to 1 g/m2 per month) or orally (1 to 2 mg/kg per day). Other immunosuppressive regimens included azathioprine, mycophenolate mofetil, and cyclosporine, usually after completion of induction therapy. The duration of therapy with various immunosuppressive medications was recorded. Patients were considered to be treated if they received any immunosuppressive therapy, regardless of duration. Medical records were reviewed on an ongoing basis. Drs. Falk and Nachman determined the outcomes, which included treatment resistance, remission while receiving therapy, remission without therapy, relapse, and end-stage kidney disease (4, 7). Treatment resistance was defined as progressive decline in kidney function with persistence of active urine sediment, or new or persisting extrarenal manifestations of vasculitis despite immunosuppressive therapy. Resistance to therapy was determined at least 1 month after the start of treatment. Remission was defined as stabilization or improvement of kidney function as measured by serum creatinine levels and resolution of hematuria and other manifestations of systemic vasculitis for more than 1 month. Remission without therapy was defined as remission while receiving only 7.5 mg of corticosteroids per day or less. Relapse could only occur in patients who reached remission (with or without therapy). Relapse was defined as vasculitic signs or symptoms in any organ system, as previously described (4, 7). Histopathologic renal evaluations included assessment of disease activity, chronicity, and vascular sclerosis. Scores ranging from 0 to 4 were used to designate degrees of glomerular necrosis, cellular crescents, neutrophil infiltration, capillary wall thickening, glomerular hypercellularity, and interstitial leukocytes; the sum of these scores was used to grade overall renal activity (range, 0 to 24). Chronicity was quantified by the sum of the scores (0 to 4 for each) for glomerular sclerosis, fibrotic crescents, interstitial fibrosis, and tubular atrophy (range, 0 to 16). Vascular sclerosis was scored from 0 to 4. The 4-variable Modification of Diet in Renal Disease equation (13, 14) was used to estimate glomerular filtration rate (GFR). Improvement or decline in GFR of 8 mL/min or more over 4 months was considered a clinically significant change in renal function. Statistical Analyses Logistic regression was used to assess factors associated with treatment resistance. A time-to-event analysis was not used because actual time to resistance is not known and because outcomes occurred within a short time. Results were expressed as odds ratios with 95% CIs. KaplanMeier estimators were used to estimate median survival times and probability of survival without end-stage kidney disease (15, 16). Cause-specific proportional hazards models were used to study, as competing risks, the 2 mutually exclusive outcomes of time to relapse (active disease outcome) and time to end-stage kidney disease

Predictors of treatment resistance and relapse in antineutrophil cytoplasmic antibody–associated small‐vessel vasculitis: Comparison of two independent cohorts

OBJECTIVE Predictors of treatment resistance and relapse have been identified in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in the Glomerular Disease Collaborative Network (GDCN) in the southeastern US. This study was undertaken to evaluate the applicability of those predictors in an independent cohort followed up by the French Vasculitis Study Group. METHODS Predictors of treatment resistance were evaluated using logistic regression models and reported as odds ratios (ORs) with 95% confidence intervals (95% CIs). Predictors of relapse were evaluated using Cox proportional hazards models and reported as hazard ratios (HRs) with 95% CIs. Models were controlled for age, sex, race, baseline serum creatinine level, and cyclophosphamide therapy. RESULTS The French cohort (n = 434) and the GDCN cohort (n = 350) had similar median followup periods (44 months versus 45 months) and initial percentages of patients taking cyclophosphamide (82% versus 78%). The French cohort included more patients with proteinase 3 (PR3) ANCA (58% versus 40%), lung involvement (58% versus 49%), and upper respiratory tract involvement (62% versus 31%). Of the predictors of treatment resistance in the GDCN cohort (female sex, African American race, presence of myeloperoxidase ANCA, elevated creatinine level, and age), only age predicted treatment resistance in the French cohort (OR 1.32 per 10 years [95% CI 1.05-1.66]). Predictors of relapse in the GDCN cohort were PR3 ANCA (HR 1.77 [95% CI 1.11-2.82]), lung involvement (HR 1.68 [95% CI 1.10-2.57), and upper respiratory tract involvement (HR 1.58 [95% CI 1.00-2.48]), while predictors in the French cohort were PR3 ANCA (HR 1.66 [95% CI 1.15-2.39]) and lung involvement (HR 1.56 [95% CI 1.11-2.20]), but not upper respiratory tract involvement (HR 0.96 [95% CI 0.67-1.38]). CONCLUSION Our findings indicate that older age is a predictor of treatment resistance, and that PR3 ANCA and lung involvement are predictors of relapse in both cohorts. Discrepancies in predictors of treatment tract resistance may reflect differences in access to care, and differences in predictors of relapse may reflect variations in disease expression.

Classification of antineutrophil cytoplasmic autoantibody vasculitides: the role of antineutrophil cytoplasmic autoantibody specificity for myeloperoxidase or proteinase 3 in disease recognition and prognosis.

OBJECTIVE To compare the usefulness of 3 currently used classification systems in predicting the outcomes of treatment resistance, disease relapse, end-stage renal disease (ESRD), and death in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS Three classification systems were applied to 502 patients with biopsy-proven AAV: 1) the Chapel Hill Consensus Conference (CHCC) definition with categories for granulomatosis with polyangiitis (GPA) (Wegeners), microscopic polyangiitis (MPA), and kidney-limited disease; 2) the European Medicines Agency (EMA) system with categories for GPA and MPA; and 3) classification based on ANCA with specificity for myeloperoxidase (MPO ANCA) versus ANCA with specificity for proteinase 3 (PR3 ANCA). Outcomes included treatment resistance, relapse, ESRD, and death. Proportional hazards models were compared between systems using an information-theoretic approach to rank models by predictive fit. Hazard ratios (HRs) with 95% confidence intervals (95% CIs) and P values are reported. RESULTS ANCA specificity was predictive of relapse, with PR3 ANCA-positive patients almost twice as likely to relapse as those with MPO ANCA (HR 1.89 [95% CI 1.33-2.69], P = 0.0004), and ANCA specificity had the best predictive model fit (model rank 1) compared to the CHCC and EMA systems. The CHCC and EMA systems did not predict relapse. By ANCA specificity, categories of GPA, MPA, and kidney-limited disease did not distinguish differences in probability of relapse-free survival. None of the systems predicted treatment resistance, ESRD, or death. CONCLUSION ANCA specificity independently predicts relapse among patients with AAV with renal disease. Classification and diagnostic systems that incorporate ANCA specificity, such as PR3 ANCA-positive MPA and MPO ANCA-positive MPA, provide a more useful tool than the clinical pathologic category alone for predicting relapse.

Rituximab therapy in idiopathic membranous nephropathy: a 2-year study.

BACKGROUND AND OBJECTIVES It was postulated that in patients with membranous nephropathy (MN), four weekly doses of Rituximab (RTX) would result in more effective B cell depletion, a higher remission rate, and maintaining the same safety profile compared with patients treated with RTX dosed at 1 g every 2 weeks. This hypothesis was supported by previous pharmacokinetic (PK) analysis showing that RTX levels in the two-dose regimen were 50% lower compared with nonproteinuric patients, which could potentially result in undertreatment. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Twenty patients with MN and proteinuria >5 g/24 h received RTX (375 mg/m(2) × 4), with re-treatment at 6 months regardless of proteinuria response. PK analysis was conducted simultaneously with immunological analyses of T and B cells to ascertain the effect of RTX on lymphocyte subpopulations. RESULTS Baseline proteinuria of 11.9 g/24 h decreased to 4.2 and 2.0 g/24 h at 12 and 24 months, respectively, whereas creatinine clearance increased from 72.4 ml/min per 1.73 m(2) at baseline to 88.4 ml/min per 1.73 m(2) at 24 months. Of 18 patients who completed 24-month follow-up, 4 are in complete remission, 12 are in partial remission, 1 has a limited response, and 1 patient relapsed. Serum RTX levels were similar to those obtained with two doses of RTX. CONCLUSIONS Four doses of RTX resulted in more effective B cell depletion, but proteinuria reduction was similar to RTX at 1 g every 2 weeks. Baseline quantification of lymphocyte subpopulations did not predict response to RTX therapy.

Epitope specificity determines pathogenicity and detectability in ANCA-associated vasculitis

Anti-neutrophil cytoplasmic antibody-associated (ANCA-associated) small vessel necrotizing vasculitis is caused by immune-mediated inflammation of the vessel wall and is diagnosed in some cases by the presence of myeloperoxidase-specific antibodies (MPO-ANCA). This multicenter study sought to determine whether differences in ANCA epitope specificity explain why, in some cases, conventional serologic assays do not correlate with disease activity, why naturally occurring anti-MPO autoantibodies can exist in disease-free individuals, and why ANCA are undetected in patients with ANCA-negative disease. Autoantibodies from human and murine samples were epitope mapped using a highly sensitive epitope excision/mass spectrometry approach. Data indicated that MPO autoantibodies from healthy individuals had epitope specificities different from those present in ANCA disease. Importantly, this methodology led to the discovery of MPO-ANCA in ANCA-negative disease that reacted against a sole linear sequence. Autoantibodies against this epitope had pathogenic properties, as demonstrated by their capacity to activate neutrophils in vitro and to induce nephritis in mice. The confounder for serological detection of these autoantibodies was the presence of a fragment of ceruloplasmin in serum, which was eliminated in purified IgG, allowing detection. These findings implicate immunodominant epitopes in the pathology of ANCA-associated vasculitis and suggest that autoantibody diversity may be common to other autoimmune diseases.

Design of the nephrotic syndrome study network (NEPTUNE) to evaluate primary glomerular nephropathy by a multidisciplinary approach

The Nephrotic Syndrome Study Network (NEPTUNE) is a North American multi-center collaborative consortium established to develop a translational research infrastructure for Nephrotic Syndrome. This includes a longitudinal observational cohort study, a pilot and ancillary studies program, a training program, and a patient contact registry. NEPTUNE will enroll 450 adults and children with minimal change disease, focal segmental glomerulosclerosis and membranous nephropathy for detailed clinical, histopathologic, and molecular phenotyping at the time of clinically-indicated renal biopsy. Initial visits will include an extensive clinical history, physical examination, collection of urine, blood and renal tissue samples, and assessments of quality of life and patient-reported outcomes. Follow-up history, physical measures, urine and blood samples, and questionnaires will be obtained every 4 months in the first year and bi-annually, thereafter. Molecular profiles and gene expression data will be linked to phenotypic, genetic, and digitalized histologic data for comprehensive analyses using systems biology approaches. Analytical strategies were designed to transform descriptive information to mechanistic disease classification for Nephrotic Syndrome and to identify clinical, histological, and genomic disease predictors. Thus, understanding the complexity of the disease pathogenesis will guide further investigation for targeted therapeutic strategies.

Venous Thromboembolism in Patients with Membranous Nephropathy

BACKGROUND AND OBJECTIVES The aims of this study were to determine the frequency of venous thromboembolic events in a large cohort of patients with idiopathic membranous nephropathy and to identify predisposing risk factors. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We studied patients with biopsy-proven membranous nephropathy from the Glomerular Disease Collaborative Network (n=412) and the Toronto Glomerulonephritis Registry (n=486) inception cohorts. The cohorts were pooled after establishing similar baseline characteristics (total n=898). Clinically apparent and radiologically confirmed venous thromboembolic events were identified. Potential risk factors were evaluated using multivariable logistic regression models. RESULTS Sixty-five (7.2%) subjects had at least one venous thromboembolic event, and this rate did not differ significantly between registries. Most venous thromboembolic events occurred within 2 years of first clinical assessment (median time to VTE = 3.8 months). After adjusting for age, sex, proteinuria, and immunosuppressive therapy, hypoalbuminemia at diagnosis was the only independent predictor of a venous thromboembolic event. Each 1.0 g/dl reduction in serum albumin was associated with a 2.13-fold increased risk of VTE. An albumin level <2.8 g/dl was the threshold below which risk for a venous thromboembolic event was greatest. CONCLUSIONS We conclude that clinically apparent venous thromboembolic events occur in about 7% of patients with membranous nephropathy. Hypoalbuminemia, particularly <2.8 g/dl, is the most significant independent predictor of venous thrombotic risk.

Rituximab Therapy for Membranous Nephropathy: A Systematic Review

BACKGROUND AND OBJECTIVES The treatment of membranous nephropathy (MN) remains controversial. Rituximab, which selectively targets B cells, has emerged as a possible alternative treatment option with limited toxicity. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The available data on rituximab therapy for MN were reviewed using the MEDLINE database (inception to August 1, 2008), Google Scholar, and selected reference lists. English-language studies investigating the use of rituximab in idiopathic and secondary MN, in native and transplanted kidneys, were included. Study design, subject number, clinical characteristics (diagnosis, previous and concomitant treatment courses, baseline proteinuria, baseline renal function), rituximab protocol, follow-up period, achievement of complete or partial remission, changes in proteinuria and renal function, and adverse effects of therapy were extracted. RESULTS Twenty-one articles were included for review; all were either case reports or case series without controls. More than half of the published cases (50 of 85) came from one center where rituximab was used as primary immunosuppression for idiopathic MN. The available data suggest that rituximab, dosed either as 375 mg/m(2) once weekly for 4 wk or as 1 g on days 1 and 15, achieves a 15 to 20% rate of complete remission and a 35 to 40% rate of partial remission. The drug was well tolerated with minimal adverse events. CONCLUSIONS Although rituximab may prove to be a better treatment option for MN than alkylating agents or calcineurin inhibitors, the current literature only supports using the drug in research protocols. Whether, when, how, and why to use rituximab in MN remains to be determined.

Disease-specific risk of venous thromboembolic events is increased in idiopathic glomerulonephritis

The risk of venous thromboembolic events is thought to be highest in patients with membranous nephropathy. This association has been recently questioned, and it is not known whether this simply reflects the severity of proteinuria. To better understand the relationship between histologic diagnosis and the risk of venous thromboembolic events we evaluated patients in the Toronto Glomerulonephritis Registry. Of 1313 patients with idiopathic glomerulonephritis, 395 were diagnosed with membranous nephropathy, 370 with focal segmental glomerulosclerosis (FSGS), and 548 with immunoglobulin-A nephropathy (IgAN). Risk factors were evaluated by Cox proportional hazards for 53 image-confirmed venous thromboembolic events in 44 patients during a median follow-up of 63 months. The risk was highest in patients with membranous nephropathy and FSGS (hazard ratios of 22 and 7.8, respectively) referenced to patients with IgAN. Following adjustment for gender, cancer history, proteinuria, and serum albumin by multivariable analysis, the histologic subtype remained an independent risk for venous thromboembolic events. This risk was still highest in patients with membranous nephropathy followed by FSGS with adjusted hazard ratios of 10.8 and 5.9, respectively. Thus, in this large cohort, histologic diagnosis was an independent risk factor for venous thromboembolic events. Further studies are needed to discover mechanisms responsible for this high risk in patients with membranous nephropathy.

Glucocorticoids and Relapse and Infection Rates in Anti-Neutrophil Cytoplasmic Antibody Disease

BACKGROUND AND OBJECTIVES The optimal course of glucocorticoid therapy in anti-neutrophil cytoplasmic autoantibody (ANCA) disease is unknown. This cohort study evaluates effects of glucocorticoid therapy duration on patient outcomes and adverse events. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS This study assessed 147 patients diagnosed between January 1, 2000 and January 1, 2009 who were treated with glucocorticoids and cyclophosphamide. Patients with end stage kidney disease at presentation, treatment resistance, or who had died within 6 months were excluded. Patients were divided into three groups: 0, 5, or >5 mg prednisone daily at 6 months after therapy initiation. The latter two groups were combined for assessment of adverse events. Wilcoxon rank sum, Kruskal-Wallis, or Fishers exact tests were used for between-group comparisons. Time to relapse was evaluated by the Kaplan-Meier method with log-rank test for comparison. RESULTS There were no differences between groups in ANCA specificity, serum creatinine, frequency of risk factors for relapse, or length of therapy with immunosuppressants. Length of glucocorticoid therapy had no impact on time to relapse (hazard ratio, 0.69 [95% confidence interval (CI), 0.23-2.02]; 1.01, [95% CI, 0.57-1.81] for the 5-mg and >5-mg groups, respectively), relapse-free survival, end stage kidney disease, or death. Patients receiving glucocorticoids beyond 6 months had significantly higher incidence of infections (0.64 infections per person-year versus 0.39, P<0.0001) and a marginally significant higher frequency of new-onset diabetes mellitus (odds ratio, 2.03; 95% CI, 0.94-4.38). CONCLUSIONS Glucocorticoid therapy beyond 6 months is associated with a significantly greater risk of infections but not a significantly decreased risk of relapse.