Kidney Histopathology Can Predict Kidney Function in ANCA-Associated Vasculitides with Acute Kidney Injury Treated with Plasma Exchanges

Kidney Failure in Pauci-immune Crescentic Glomerulonephritis: Rationale for Immunosuppression to Improve Kidney Outcome

PURPOSE OF REVIEW

Pauci-immune crescentic glomerulonephritis is the hallmark finding in ANCA-associated vasculitis (AAV) when the kidneys are affected. The rationale for immunosuppression in AAV is based on the underlying autoimmune nature of the disease. Overall remission rates, kidney outcomes, and the burden of disease have greatly improved since the discovery of various immunosuppressive therapies, but relapses remain common, and a significant proportion of patients continue to progress to end-stage kidney disease. Here, we review the role of immunosuppressive therapies for the treatment of pauci-immune crescentic glomerulonephritis.

RECENT FINDINGS

Besides the recognized role of B and T cells in the pathogenies of AAV, the focus on the contribution of inflammatory cytokines, neutrophil extracellular traps (NETs), and the complement system allowed the discovery of new therapies. Specifically, the C5a receptor blocker (avacopan) has been approved as a glucocorticoid-sparing agent. Additionally, based on observational data, more clinicians are now using combination therapies during the induction phase. There is also an evolving understanding of the role of plasma exchange in removing ANCA antibodies. Furthermore, the recent development of risk score systems provides physicians with valuable prognostic information that can influence decisions on immunosuppression, although future validation from larger cohorts is needed. The over-activation of various immune pathways plays a significant role in the pathogenesis of pauci-immune crescentic glomerulonephritis in AAV. Immunosuppression is, therefore, an important strategy to halt disease progression and improve overall outcomes. Relapse prevention while minimizing adverse events of immunosuppression is a major long-term goal in AAV management.

Predictive Factors of Renal Recovery and Progression to End-Stage Kidney Disease in Patients With Antineutrophil Cytoplasmic Autoantibody-Associated Vasculitis With Severe Kidney Disease

Introduction

A significant number of patients with antineutrophil cytoplasmic antibodies (ANCA)- associated vasculitis (AAV) with glomerulonephritis (AAV-GN) still progress to end-stage kidney disease (ESKD, estimated glomerular filtration rate [eGFR] <15 ml/min per 1.73 m2) despite advances in remission-induction treatment.

Methods

This is a retrospective cohort study on myeloperoxidase (MPO)-ANCA or proteinase 3 (PR3)-ANCA positive patients with AAV (microscopic polyangiitis, MPA; or granulomatosis with polyangiitis, GPA) and eGFR <15 ml/min per 1.73 m2 or ESKD at presentation. Renal recovery, dialysis discontinuation, and persistence of ESKD after standard remission-induction, with or without the use of plasma exchange (PLEX) were analyzed.

Results

We analyzed 166 patients with biopsy-proven active AAV-GN and eGFR <15 ml/min per 1.73 m2 at the time of diagnosis. Patients received glucocorticoids with cyclophosphamide (CYC) (n = 84) or with rituximab (RTX) (n = 72) for remission-induction, and 49 received PLEX. The predictors of renal recovery were erythrocyte sedimentation rate, serum creatinine (SCr) at diagnosis, and minimal or mild chronicity changes. We further analyzed 71 patients who started dialysis with or without PLEX within 4 weeks of AAV-GN diagnosis. The predictors of dialysis discontinuation were minimal chronicity changes in kidney biopsy at diagnosis (odds ratio = 6.138; 95% confidence interval [CI]: 1.389-27.118; P = 0.017). Predictors of persistence of ESKD within 12 months included higher SCr at diagnosis (incidence rate ratio [IRR] = 1.086; 95% CI: 1.005-1.173; P = 0.037), and moderate (IRR = 3.797; 95% CI: 1.090-13.225; P = 0.036), or severe chronicity changes in kidney biopsy (IRR = 5.883; 95% CI: 1.542-22.439; P =0.009).

Conclusion

In our cohort, kidney recovery, dialysis discontinuation, and persistence of ESKD in patients with AAV-GN and eGFR <15 ml/min per 1.73 m2 depended on SCr and histologic findings on kidney biopsies at the time of diagnosis and was not affected by the addition of PLEX.

The Improved Kidney Risk Score in ANCA-Associated Vasculitis for Clinical Practice and Trials

SIGNIFICANCE STATEMENT

Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. More than 1500 patients were collated in an international longitudinal study to revise the ANCA kidney risk score. The score showed satisfactory performance, mimicking the original study (Harrell's C=0.779). In the development cohort of 959 patients, no additional parameters aiding the tool were detected, but replacing the GFR with creatinine identified an additional cutoff. The parameter interstitial fibrosis and tubular atrophy was modified to allow wider access, risk points were reweighted, and a fourth risk group was created, improving predictive ability (C=0.831). In the validation, the new model performed similarly well with excellent calibration and discrimination ( n =480, C=0.821). The revised score optimizes prognostication for clinical practice and trials.

BACKGROUND

Reliable prediction tools are needed to personalize treatment in ANCA-associated GN. A retrospective international longitudinal cohort was collated to revise the ANCA renal risk score.

METHODS

The primary end point was ESKD with patients censored at last follow-up. Cox proportional hazards were used to reweight risk factors. Kaplan-Meier curves, Harrell's C statistic, receiver operating characteristics, and calibration plots were used to assess model performance.

RESULTS

Of 1591 patients, 1439 were included in the final analyses, 2:1 randomly allocated per center to development and validation cohorts (52% male, median age 64 years). In the development cohort ( n =959), the ANCA renal risk score was validated and calibrated, and parameters were reinvestigated modifying interstitial fibrosis and tubular atrophy allowing semiquantitative reporting. An additional cutoff for kidney function (K) was identified, and serum creatinine replaced GFR (K0: <250 µ mol/L=0, K1: 250-450 µ mol/L=4, K2: >450 µ mol/L=11 points). The risk points for the percentage of normal glomeruli (N) and interstitial fibrosis and tubular atrophy (T) were reweighted (N0: >25%=0, N1: 10%-25%=4, N2: <10%=7, T0: none/mild or <25%=0, T1: ≥ mild-moderate or ≥25%=3 points), and four risk groups created: low (0-4 points), moderate (5-11), high (12-18), and very high (21). Discrimination was C=0.831, and the 3-year kidney survival was 96%, 79%, 54%, and 19%, respectively. The revised score performed similarly well in the validation cohort with excellent calibration and discrimination ( n =480, C=0.821).

CONCLUSIONS

The updated score optimizes clinicopathologic prognostication for clinical practice and trials.

Relevance of histopathological findings for predictive scoring of short-term treatment response to plasma exchange in severe ANCA-associated renal vasculitides

Introduction

Rapidly progressive glomerulonephritis (RPGN) is characterized by a rapid loss of kidney function, affecting both renal and overall patient survival. Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a small vessel vasculitis affecting multiple organ systems including the kidney, and among most frequent causes of RPGN. We here aimed to validate a recently described scoring system for short-term treatment response to therapeutic plasma exchange (PLEX) in a well-characterized and independent cohort of severe renal AAV presenting with RPGN. Furthermore, we compared this scoring with established classification systems in renal AAV including histopathological findings.

Methods

We here directly compare the scoring system with retrospective data about PLEX treatment in our own clinical practice and according to current recommendations in a cohort of 53 patients with severe AAV presenting with RPGN confirmed by kidney biopsy.

Results

We here confirm that PLEX scoring is capable to identify patients at risk for short-term poor outcome in severe AAV presenting with RPGN (p<0.0001). Furthermore, multiple stepwise regression analysis revealed that the PLEX score with renal biopsy performed best to predict poor outcome in this patient population (p<0.0001).

Conclusion

Our observations underscore the relevance of performing a kidney biopsy in this patient population that is often challenged in the setting of intensive care treatment, requirement of KRT with need for anticoagulation and bleeding risk. Therefore, validation of our observations and this recent scoring system for treatment response to PLEX in independent cohorts would be of great clinical relevance in the treatment of patients with severe AAV presenting with RPGN.

Plasma exchange in patients with ANCA-associated vasculitis

ANCA-associated Vasculitides (AAV) are characterized by small vessel necrotizing inflammation and can present with multisystem organ involvement, including organ/life threatening manifestations of rapidly progressive glomerulonephritis and diffuse alveolar haemorrhage, where immediate and aggressive intervention is needed to prevent further organ damage. Although, the rationale of plasma exchange (PLEX) in AAV is strong, through removing the pathogenic ANCAs; target either myeloperoxidase (MPO) or proteinase 3 (PR3), and other inflammatory molecules, especially in the initiation when the immunosuppressive treatment is no sufficient to prevent the organ damage, overall impact on patient outcomes is not well-established, while the risk of infections seems to be higher in the PLEX-treated patients. A comprehensive overview of the challenges and uncertainties surrounding the use of PLEX in the management of AAV will be reviewed, providing the current practice recommendations guiding treatment decisions.

EULAR recommendations for the management of ANCA-associated vasculitis: 2022 update

BACKGROUND

Since the publication of the EULAR recommendations for the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in 2016, several randomised clinical trials have been published that have the potential to change clinical care and support the need for an update.

METHODS

Using EULAR standardised operating procedures, the EULAR task force undertook a systematic literature review and sought opinion from 20 experts from 16 countries. We modified existing recommendations and created new recommendations.

RESULTS

Four overarching principles and 17 recommendations were formulated. We recommend biopsies and ANCA testing to assist in establishing a diagnosis of AAV. For remission induction in life-threatening or organ-threatening AAV, we recommend a combination of high-dose glucocorticoids (GCs) in combination with either rituximab or cyclophosphamide. We recommend tapering of the GC dose to a target of 5 mg prednisolone equivalent/day within 4-5 months. Avacopan may be considered as part of a strategy to reduce exposure to GC in granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA). Plasma exchange may be considered in patients with rapidly progressive glomerulonephritis. For remission maintenance of GPA/MPA, we recommend rituximab. In patients with relapsing or refractory eosinophilic GPA, we recommend the use of mepolizumab. Azathioprine and methotrexate are alternatives to biologics for remission maintenance in AAV.

CONCLUSIONS

In the light of recent advancements, these recommendations provide updated guidance on AAV management. As substantial data gaps still exist, informed decision-making between physicians and patients remains of key relevance.

ANCA-Associated Vasculitis: Practical Issues in Management

ANCA associated vasculitides are multi-system autoimmune diseases which are increasing in prevalence. In this review we will discuss the clinical manifestations and review the management options. We highlight the various trials of induction and maintenance therapy and discuss the areas of unmet need. These include understanding which patients are at highest risk of relapse, clinical adaptation of improved biomarkers of disease activity and tools to discuss long term prognosis.

Management of antineutrophil cytoplasmic antibody-associated vasculitis with glomerulonephritis as proposed by the ACR 2021, EULAR 2022 and KDIGO 2021 guidelines/recommendations

Updated guidelines on the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) were released in 2021 by the American College of Rheumatology jointly with the Vasculitis Foundation and, subsequently, in 2022 by the European Alliance of Associations for Rheumatology. In addition, in 2021, the Kidney Disease: Improving Global Outcomes had released updated recommendations on the treatment of AAV with glomerulonephritis (AAV-GN). Kidney involvement is particularly relevant in microscopic polyangiitis and granulomatosis with polyangiitis, but is less frequent in eosinophilic granulomatosis with polyangiitis. The management of AAV-GN has been a focus for drug development and change over the past 10 years. Avoidance of progression to end-stage kidney disease (ESKD) or kidney failure is one of the main unmet needs in the management of AAV, with ESKD having a major impact on morbidity, health costs and mortality risk. Relevant changes in AAV-GN management are related to remission-induction treatment of patients with severe kidney disease, the use of glucocorticoids and avacopan, and remission-maintenance treatment. All the documents provide guidance in accordance with the evidence-based standard of care available at the time of their release. With our work we aim to (i) show the progress made and identify the differences between guidelines and recommendations, (ii) discuss the supporting rationale for those, and (iii) identify gaps in knowledge that could benefit from additional research and should be revised in subsequent updates.

Case Report: Immune checkpoint inhibitor-induced multiorgan vasculitis successfully treated with rituximab

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. ICIs have a unique side effect profile, generally caused by inflammatory tissue damage, with clinical features similar to autoimmune conditions. Acute kidney injury from ICIs has been well studied; incidence ranges from 1% to 5%, with higher incidence when combination ICI therapies are used. Although the overall reported incidence of ICI-associated glomerulonephritis is less than 1%, vasculitis is the most commonly reported ICI-related glomerulonephritis. Other biopsy findings include thrombotic microangiopathy, focal segmental glomerulosclerosis, minimal change disease, and IgA nephropathy with secondary amyloidosis. We report a case in which a woman previously treated with the PD-L1 inhibitor durvalumab for locally advanced non-small cell lung cancer with pre-existing antineutrophil cytoplasmic (anti-PR3) antibody who later developed multi-organ vasculitis after ICI exposure, which was successfully treated with rituximab, with continued cancer remission for 3 years.

Systematic literature review informing the 2022 update of the EULAR recommendations for the management of ANCA-associated vasculitis (AAV): part 1-treatment of granulomatosis with polyangiitis and microscopic polyangiitis

OBJECTIVE

To summarise and update evidence to inform the 2022 update of the EULAR recommendations for the management of antineutrophil cytoplasm antibody-associated vasculitis (AAV).

METHODS

A systematic literature review (SLR) was performed to identify current evidence regarding treatment of AAV. PubMed, EMBASE and the Cochrane library were searched from 1 February 2015 to 25 February 2022. The evidence presented here is focused on the treatment of granulomatosis with polyangiitis and microscopic polyangiitis.

RESULTS

3517 articles were screened and 175 assessed by full-text review. Ninety articles were included in the final evidence synthesis. Cyclophosphamide and rituximab (RTX) show similar efficacy for remission induction (level of evidence (LoE) 1a) but RTX is more effective in relapsing disease (LoE 1b). Glucocorticoid (GC) protocols with faster tapering result in similar remission rates but lower rates of serious infections (LoE 1b). Avacopan can be used to rapidly taper and replace GC (LoE 1b). Data on plasma exchange are inconsistent depending on the analysed trial populations but meta-analyses based on randomised controlled trials demonstrate a reduction of the risk of end-stage kidney disease at 1 year but not during long-term follow-up (LoE 1a). Use of RTX for maintenance of remission is associated with lower relapse rates compared with azathioprine (AZA, LoE 1b). Prolonged maintenance treatment results in lower relapse rates for both, AZA (LoE 1b) and RTX (LoE 1b).

CONCLUSION

This SLR provides current evidence to inform the 2022 update of the EULAR recommendations for the management of AAV.

Challenges of defining renal response in ANCA-associated vasculitis: call to action?

Avoiding end-stage kidney disease in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) has a high therapeutic priority. Although renal response is a crucial measure to capture clinically relevant changes, clinal trials have used various definitions and no well-studied key surrogate markers to predict renal outcome in AAV exist. Differences in clinical features and histopathologic and therapeutic approaches will influence the course of kidney function. Its assessment through traditional surrogates (i.e. serum creatinine, glomerular filtration rate, proteinuria, hematuria and disease activity scores) has limitations. Refinement of these markers and the incorporation of novel approaches such as the assessment of histopathological changes using cutting-edge molecular and machine learning mechanisms or new biomarkers could significantly improve prognostication. The timing is favourable since large datasets of trials conducted in AAV are available and provide a valuable resource to establish renal surrogate markers and, likely, aim to investigate optimized and tailored treatment approaches according to a renal response score. In this review we discuss important points missed in the assessment of kidney function in patients with AAV and point towards the importance of defining renal response and clinically important short- and long-term predictors of renal outcome.

Management of antineutrophil cytoplasmic antibody-associated vasculitis: a changing tide

PURPOSE OF REVIEW

Antineutrophil cytoplasmic antibody associated vasculitis (AAV) is a group of autoimmune disorders of small blood vessels. While outcomes in AAV have improved with the use of glucocorticoids (GC) and other immunosuppressants, these treatments are associated with significant toxicities. Infections are the major cause of mortality within the first year of treatment. There is a move towards newer treatments with better safety profiles. This review reflects on recent advances in the treatment of AAV.

RECENT FINDINGS

The role of plasma exchange (PLEX) in AAV with kidney involvement has been clarified with new BMJ guideline recommendations following the publication of PEXIVAS and an updated meta-analysis. Lower dose GC regimens are now standard of care. Avacopan (C5a receptor antagonist) was noninferior to a regimen of GC therapy and is a potential steroid-sparing agent. Lastly, rituximab-based regimens were noninferior to cyclophosphamide in two trials for induction of remission and superior to azathioprine in one trial of maintenance of remission.

SUMMARY

AAV treatments have changed tremendously over the past decade with a drive towards targeted PLEX use, increased rituximab use and lower GC dosing. Striking a crucial balance between morbidity from relapses and toxicities from immunosuppression remains a challenging path to navigate.

Plasma exchange as an adjunctive therapy in anti-neutrophil cytoplasm antibody-associated vasculitis

INTRODUCTION

We summarize evidence for the role of therapeutic plasma exchange (TPE) in the treatment of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). TPE rapidly removes ANCA IgG, complement and coagulation factors important in the pathogenesis of AAV. TPE has been used in patients with rapidly deteriorating renal function to achieve early disease control, allowing time for immunosuppressive agents to prevent resynthesis of ANCA. The PEXIVAS trial challenged the utility of TPE in AAV, as it did not show benefit of adjunctive TPE on a combined end point of end stage kidney disease (ESKD) and death.

AREAS COVERED

We analyze data from PEXIVAS and other trials of TPE in AAV, an up-to-date meta-analysis, and recently published large cohort studies.

EXPERT OPINION

There remains a role for the use of TPE in AAV in certain groups of patients, in particular those with severe renal involvement (Cr >500 μmol/L or dialysis-dependent). It should be considered in patients with Cr >300 μmol/L and rapidly deteriorating function, or with life-threatening pulmonary hemorrhage. A separate indication is patients double positive for anti-GBM antibodies and ANCA. TPE may have the greatest benefit as part of steroid-sparing immunosuppressive treatment strategies.

Advances in remission induction therapy for ANCA-associated vasculitis

Since its first description 40 years ago, huge strides have been made in the management of ANCA-associated vasculitis with improved patient outcomes. The use of cyclophosphamide and/or B-cell depleting therapy alongside glucocorticoids remains the cornerstone of therapy in organ or life-threatening disease, but recent trials have re-evaluated existing treatment strategies, alongside the development of new treatment targets. This has led to refinement of the role of plasma exchange, the use of reduced dosing of oral glucocorticoids with improved patient outcomes, as well as other treatment adjuvants/options of steroid minimization including C5a receptor antagonism and IL-5 inhibition. In this review we examine developments in remission induction therapy for ANCA-associated vasculitis.

How best to manage relapse and remission in ANCA-associated vasculitis

INTRODUCTION

A 2-stage therapeutic approach is now applied as standard-of-care to treat ANCA-associated vasculitides (AAVs): first, glucocorticoids (GCs) combined with cyclophosphamide (CYC) or rituximab (RTX) to induce remission, then relapse prevention with remission-maintenance therapy. Nonetheless, a substantial risk of relapse persists.

AREAS COVERED

The authors provide an overview of the current state of maintenance therapies, and discuss new strategies recommended to prevent and treat relapses, focusing on granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

EXPERT OPINION

For remission-induction after GPA or MPA relapse with organ-threatening manifestations, reintroduction or intensification of the GC dose in combination with CYC or RTX cycle is recommended; we prefer RTX in light of its superior responses obtained in patients with relapsing disease. Rapid tapering of GCs has been shown not to alter AAV evolution while decreasing the risk of serious infections. In contrast, for non-severe, active MPA, we recommend GCs alone as first-line therapy. For patients whose MPA remains uncontrolled by GCs alone, immunosuppressant adjunction can be a GC-sparing option or to counter GC intolerance. Once remission is achieved, we recommend prolonged maintenance therapy with preemptive low-dose (500 mg) RTX infusion biannually.

Clinical value of urinary cytokines/chemokines as prognostic markers in patients with crescentic glomerulonephritis

Crescentic glomerulonephritis (CrGN) usually requires urgent immunosuppressive treatment. However, aggressive immunosuppressive treatment is often difficult because of the patients' medical conditions or comorbidities. Prognostic markers including urinary cytokines/chemokines as noninvasive biomarkers were explored in CrGN patients. This prospective cohort study included 82 patients with biopsy-confirmed CrGN from 2002 to 2015 who were followed up for 5 years. Urine and serum cytokines/chemokines on the day of kidney biopsy were analyzed in 36 patients. The median age was 65 years and 47.6% were male. Baseline estimated glomerular filtration rate (eGFR) and interstitial fibrosis and tubular atrophy (IFTA) scores were identified as significant prognostic factors. Among patients with cytokines/chemokines measurement, increased IL-10 level was identified as an independent predictor of good prognosis, and increased levels of urinary MCP-1 and fractalkine tended to be associated with good prognosis after adjusting for baseline eGFR and IFTA score. However, semiquantitative analysis of intrarenal leukocytes did not show prognostic value predicting renal outcome or correlation with urinary cytokines/chemokines. This study supports the clinical importance of baseline eGFR and IFTA scores and suggests potential usefulness of urinary IL-10, MCP-1, and fractalkine as prognostic markers for predicting renal outcomes in patients with CrGN.

Learning Methodological Lessons from Exemplar Studies in Nephrology: PEXIVAS and Sample Size Calculation

Sample size calculations are fundamental to the power of a study. Estimates of the necessary sample size to achieve a given treatment effect size can be performed pre-trial based on available literature.Sample size calculations take into account the chosen effect size i.e. the minimal effect of the treatment which would be considered clinically relevant. Smaller effect sizes require a sufficiently large sample size or higher event rate to detect differences between groups. Larger effect sizes are sometimes chosen for study in order to justify the risks of adverse events and expense of certain treatments.Lower than expected event rates, mediated by censoring and competing risks, period effects, and inclusion of patients at lower risk of the outcome, can impact the power of the study.Time-to-event study designs adjust for censoring and competing risks.If a lower than expected event rate is highlighted during an interim analysis, strategies include increasing the sample size, either by changing the inclusion or exclusion criteria, increasing the number of study centers or increasing the study duration.