Improving Clinical Trials for Anticomplement Therapies in Complement-Mediated Glomerulopathies: Report of a Scientific Workshop Sponsored by the National Kidney Foundation.

Blocking the complement system as a therapeutic strategy has been proposed for numerous glomerular diseases but presents myriad questions and challenges, not the least of which is demonstrating efficacy and safety. In light of these potential issues and because there are an increasing number of anticomplement therapy trials either planned or under way, the National Kidney Foundation facilitated an all-virtual scientific workshop entitled "Improving Clinical Trials for Anti-Complement Therapies in Complement-Mediated Glomerulopathies." Attended by patient representatives and experts in glomerular diseases, complement physiology, and clinical trial design, the aim of this workshop was to develop standards applicable for designing and conducting clinical trials for anticomplement therapies across a wide spectrum of complement-mediated glomerulopathies. Discussions focused on study design, participant risk assessment and mitigation, laboratory measurements and biomarkers to support these studies, and identification of optimal outcome measures to detect benefit, specifically for trials in complement-mediated diseases. This report summarizes the discussions from this workshop and outlines consensus recommendations.

Untangling immunotactoid glomerulopathy in the MGRS era.

Immunotactoid glomerulopathy (ITG) is a rare disease diagnosed by kidney biopsy showing characteristic microtubules, often in parallel arrays, in glomeruli on electron microscopy. Most cases are caused by lymphoproliferative disorders that produce monoclonal immunoglobulins that cause kidney damage, but these disorders do not meet criteria for overt malignancy. The published literature on ITG is limited. In this issue of Kidney International, 2 manuscripts provide significant insight into the clinical presentation, pathology, and treatment of ITG.

Development of an international Delphi survey to establish core outcome domains for trials in adults with glomerular disease.

Outcomes relevant to treatment decision-making are inconsistently reported in trials involving glomerular disease. Here, we sought to establish a consensus-derived set of critically important outcomes designed to be reported in all future trials by using an online, international two-round Delphi survey in English. To develop this, patients with glomerular disease, caregivers and health professionals aged 18 years and older rated the importance of outcomes using a Likert scale and a Best-Worst scale. The absolute and relative importance was assessed and comments were analyzed thematically. Of 1198 participants who completed Round 1, 734 were patients/caregivers while 464 were health care professionals from 59 countries. Of 700 participants that completed Round 2, 412 were patients/caregivers and 288 were health care professionals. Need for dialysis or transplant, kidney function, death, cardiovascular disease, remission-relapse and life participation were the most important outcomes to patients/caregivers and health professionals. Patients/caregivers rated patient-reported outcomes higher while health care professionals rated hospitalization, death and remission/relapse higher. Four themes explained the reasons for their priorities: confronting death and compounded suffering, focusing on specific targets in glomerular disease, preserving meaning in life, and fostering self-management. Thus, consistent reporting of these critically important outcomes in all trials involving glomerular disease is hoped to improve patient-centered decision-making.

APOL1 genotype-associated morphologic changes among patients with focal segmental glomerulosclerosis.

BACKGROUND: The G1 and G2 alleles of apolipoprotein L1 (APOL1) are common in the Black population and associated with increased risk of focal segmental glomerulosclerosis (FSGS). The molecular mechanisms linking APOL1 risk variants with FSGS are not clearly understood, and APOL1's natural absence in laboratory animals makes studying its pathobiology challenging. METHODS: In a cohort of 90 Black patients with either FSGS or minimal change disease (MCD) enrolled in the Nephrotic Syndrome Study Network (58% pediatric onset), we used kidney biopsy traits as an intermediate outcome to help illuminate tissue-based consequences of APOL1 risk variants and expression. We tested associations between APOL1 risk alleles or glomerular APOL1 mRNA expression and 83 light- or electron-microscopy traits measuring structural and cellular kidney changes. RESULTS: Under both recessive and dominant models in the FSGS patient subgroup (61%), APOL1 risk variants were significantly correlated (defined as FDR <0.1) with decreased global mesangial hypercellularity, decreased condensation of cytoskeleton, and increased tubular microcysts. No significant correlations were detected in MCD cohort. Independent of risk alleles, glomerular APOL1 expression in FSGS patients was not correlated with morphologic features. CONCLUSIONS: While APOL1-associated FSGS is associated with two risk alleles, both one and two risk alleles are associated with cellular/tissue changes in this study of FSGS patients. Our lack of discovery of a large group of tissue differences in FSGS and no significant difference in MCD may be due to the lack of power but also supports investigating whether machine learning methods may more sensitively detect APOL1-associated changes.

Bevacizumab-associated thrombotic microangiopathy treated with eculizumab: A case series and systematic review of the literature.

BACKGROUND: Bevacizumab is a recombinant monoclonal antibody against the vascular endothelial growth factor A (VEGF-A) ligand that is used in the management of various solid malignancies. The adverse effect profiles of angiogenesis inhibitors, such as bevacizumab, have become increasingly well characterized and include renal manifestations such as hypertension, proteinuria, and thrombotic microangiopathy. Eculizumab inhibits terminal-complement activation and is used to treat atypical hemolytic uremic syndrome. There has been growing usage of eculizumab to treat bevacizumab-associated thrombotic microangiopathy. MATERIALS AND METHODS: We performed a systematic review of the literature to identify full-text articles that describe the use of eculizumab for bevacizumab-associated thrombotic microangiopathy. RESULTS: Our systematic review identified 522 unique articles of which 5 were included in the final review. 9 cases, including 2 new cases presented in this review, were identified in which eculizumab was used in the management of bevacizumab-associated thrombotic microangiopathy. Hematologic parameters and kidney function stabilized or improved in all cases, and the 2 patients who required renal replacement therapy were able to discontinue dialysis. CONCLUSIONS: Given the findings of this systematic review, the use of eculizumab in the treatment of bevacizumab-associated thrombotic microangiopathy warrants further study, particularly in severe cases.

Clinical Features and Outcomes of Immune Checkpoint Inhibitor-Associated AKI: A Multicenter Study.

BACKGROUND: Despite increasing recognition of the importance of immune checkpoint inhibitor-associated AKI, data on this complication of immunotherapy are sparse. METHODS: We conducted a multicenter study of 138 patients with immune checkpoint inhibitor-associated AKI, defined as a ≥2-fold increase in serum creatinine or new dialysis requirement directly attributed to an immune checkpoint inhibitor. We also collected data on 276 control patients who received these drugs but did not develop AKI. RESULTS: Lower baseline eGFR, proton pump inhibitor use, and combination immune checkpoint inhibitor therapy were each independently associated with an increased risk of immune checkpoint inhibitor-associated AKI. Median (interquartile range) time from immune checkpoint inhibitor initiation to AKI was 14 (6-37) weeks. Most patients had subnephrotic proteinuria, and approximately half had pyuria. Extrarenal immune-related adverse events occurred in 43% of patients; 69% were concurrently receiving a potential tubulointerstitial nephritis-causing medication. Tubulointerstitial nephritis was the dominant lesion in 93% of the 60 patients biopsied. Most patients (86%) were treated with steroids. Complete, partial, or no kidney recovery occurred in 40%, 45%, and 15% of patients, respectively. Concomitant extrarenal immune-related adverse events were associated with worse renal prognosis, whereas concomitant tubulointerstitial nephritis-causing medications and treatment with steroids were each associated with improved renal prognosis. Failure to achieve kidney recovery after immune checkpoint inhibitor-associated AKI was independently associated with higher mortality. Immune checkpoint inhibitor rechallenge occurred in 22% of patients, of whom 23% developed recurrent associated AKI. CONCLUSIONS: This multicenter study identifies insights into the risk factors, clinical features, histopathologic findings, and renal and overall outcomes in patients with immune checkpoint inhibitor-associated AKI.

Light chain only variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits is associated with a high detection rate of the pathogenic plasma cell clone.

IgG (mainly IgG3) is the most commonly involved isotype in proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID). Here we describe the first series of PGNMID with deposition of monoclonal immunoglobulin light chain only (PGNMID-light chain). This multicenter cohort of 17 patients presented with nephritic or nephrotic syndrome with underlying hematologic conditions of monoclonal gammopathy of renal significance (71%) or multiple myeloma (29%). Monoclonal immunoglobulin was identified by serum and urine immunofixation in 65% and 73%, respectively, with abnormal serum free light chain in 83%, and a detectable bone marrow plasma cell clone in 88% of patients. Renal biopsy showed a membranoproliferative pattern in most patients. By immunofluorescence, deposits were restricted to glomeruli and composed of restricted light chain (kappa in 71%) and C3, with granular appearance and subendothelial, mesangial and subepithelial distribution by electron microscopy. Proteomic analysis in four cases of kappa PGNMID-light chain revealed spectra for kappa constant and variable domains, without evidence of Ig heavy chains; spectra for proteins of the alternative pathway of complement and terminal complex were detected in three. The classical pathway was not detected in three cases. After median follow up of 70 months, the renal response was dependent on a hematologic response and occurred in six of ten patients treated with plasma cell-directed chemotherapy but none of five patients receiving other therapies. Thus, PGNMID-light chain differs from PGNMID-IgG by higher frequency of a detectable pathogenic plasma cell clone. Hence, proper recognition is crucial as anti-myeloma agents may improve renal prognosis. Activation of an alternative pathway of complement by monoclonal immunoglobulin light chain likely plays a role in its pathogenesis.

Management and treatment of glomerular diseases (part 2): conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference.

In November 2017, the Kidney Disease: Improving Global Outcomes (KDIGO) initiative brought a diverse panel of experts in glomerular diseases together to discuss the 2012 KDIGO glomerulonephritis guideline in the context of new developments and insights that had occurred over the years since its publication. During this KDIGO Controversies Conference on Glomerular Diseases, the group examined data on disease pathogenesis, biomarkers, and treatments to identify areas of consensus and areas of controversy. This report summarizes the discussions on primary podocytopathies, lupus nephritis, anti-neutrophil cytoplasmic antibody-associated nephritis, complement-mediated kidney diseases, and monoclonal gammopathies of renal significance.

Management and treatment of glomerular diseases (part 1): conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference.

The Kidney Disease: Improving Global Outcomes (KDIGO) initiative organized a Controversies Conference on glomerular diseases in November 2017. The conference focused on the 2012 KDIGO guideline with the aim of identifying new insights into nomenclature, pathogenesis, diagnostic work-up, and, in particular, therapy of glomerular diseases since the guideline's publication. It was the consensus of the group that most guideline recommendations, in particular those dealing with therapy, will need to be revisited by the guideline-updating Work Group. This report covers general management of glomerular disease, IgA nephropathy, and membranous nephropathy.

Dysproteinemia and the Kidney: Core Curriculum 2019.

Dysproteinemic kidney diseases occur when B- or plasma cell clones produce pathogenic monoclonal immunoglobulins or light chains that cause kidney damage. The clinical presentation of these disorders ranges from sub-nephrotic-range proteinuria or microscopic hematuria with preserved kidney function to severe nephrotic syndrome to severe acute kidney injury or rapidly progressive glomerulonephritis. These monoclonal immunoglobulins can cause a variety of histologic patterns of injury, including cast nephropathy, glomerular and tubular deposition diseases, amyloidosis, and inflammatory glomerulonephritis. The underlying clonal disorder may meet criteria for overt multiple myeloma or systemic lymphoma. In recent years, there has been increased recognition and study of dysproteinemic kidney diseases that occur in the setting of smaller clonal plasma and B-cell populations, which are classified as monoclonal gammopathies of renal significance. Regardless of clonal cell burden, the goal of treatment is to achieve a hematologic response (ie, improvement or resolution of the monoclonal protein) by eradicating the underlying clone. Organ-specific responses are dependent on achieving hematologic response. Without appropriate treatment, many of these disorders are associated with high rates of progressive kidney disease and end-stage kidney disease. In this installment of AJKD's Core Curriculum in Nephrology, we review the pathogenesis, diagnosis, and treatment of dysproteinemic kidney diseases.

Heavy Chain Fibrillary Glomerulonephritis: A Case Report.

Heavy chain amyloidosis and heavy chain deposition disease are the only known kidney diseases caused by the deposition of truncated immunoglobulin heavy chains. Fibrillary glomerulonephritis typically results from deposition of DNAJB9 (DnaJ heat shock protein family [Hsp40] member B9) and polytypic immunoglobulin G (IgG). We describe a patient with monoclonal gammopathy (IgG with λ light chain) who developed DNAJB9-negative fibrillary glomerulonephritis leading to end-stage kidney disease, with recurrence in 2 kidney allografts. Pre- and postmortem examination showed glomerular deposition of Congo red-negative fibrillar material that was determined to be immunoglobulin heavy chain. We propose the term "heavy chain fibrillary glomerulonephritis" to describe this lesion, which appears to be a rare kidney complication of monoclonal gammopathy. The diagnosis should be suspected when the kidney biopsy shows fibrillary glomerulonephritis with negative staining for immunoglobulin light chains and DNAJB9; the diagnosis can be confirmed using immunochemical and molecular studies.

CureGN Study Rationale, Design, and Methods: Establishing a Large Prospective Observational Study of Glomerular Disease.

RATIONALE & OBJECTIVES: Glomerular diseases, including minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and immunoglobulin A (IgA) nephropathy, share clinical presentations, yet result from multiple biological mechanisms. Challenges to identifying underlying mechanisms, biomarkers, and new therapies include the rarity of each diagnosis and slow progression, often requiring decades to measure the effectiveness of interventions to prevent end-stage kidney disease (ESKD) or death. STUDY DESIGN: Multicenter prospective cohort study. SETTING & PARTICIPANTS: Cure Glomerulonephropathy (CureGN) will enroll 2,400 children and adults with minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, or IgA nephropathy (including IgA vasculitis) and a first diagnostic kidney biopsy within 5 years. Patients with ESKD and those with secondary causes of glomerular disease are excluded. EXPOSURES: Clinical data, including medical history, medications, family history, and patient-reported outcomes, are obtained, along with a digital archive of kidney biopsy images and blood and urine specimens at study visits aligned with clinical care 1 to 4 times per year. OUTCOMES: Patients are followed up for changes in estimated glomerular filtration rate, disease activity, ESKD, and death and for nonrenal complications of disease and treatment, including infection, malignancy, cardiovascular, and thromboembolic events. ANALYTICAL APPROACH: The study design supports multiple longitudinal analyses leveraging the diverse data domains of CureGN and its ancillary program. At 2,400 patients and an average of 2 years' initial follow-up, CureGN has 80% power to detect an HR of 1.4 to 1.9 for proteinuria remission and a mean difference of 2.1 to 3.0mL/min/1.73m2 in estimated glomerular filtration rate per year. LIMITATIONS: Current follow-up can only detect large differences in ESKD and death outcomes. CONCLUSIONS: Study infrastructure will support a broad range of scientific approaches to identify mechanistically distinct subgroups, identify accurate biomarkers of disease activity and progression, delineate disease-specific treatment targets, and inform future therapeutic trials. CureGN is expected to be among the largest prospective studies of children and adults with glomerular disease, with a broad goal to lessen disease burden and improve outcomes.

Native kidney BK virus nephropathy, a systematic review.

BACKGROUND: There is a growing base of literature describing BK nephropathy (BKVN) in patients outside of the setting of kidney transplant. Previous systematic reviews of the literature have been limited by methodology or by the scope of patients included. STUDY DESIGN AND METHODS: Systematic Review (Prospero # CRD42018088524). SETTING & POPULATION: Patients without kidney transplant who had biopsy-proven BKVN. SELECTION CRITERIA FOR STUDIES: Full-text articles that describe native BKVN patient cases. ANALYTICAL APPROACH: Descriptive synthesis. RESULTS: The search identified 630 unique articles of which 51 were included in the final review. Sixty-five cases (including two new cases presented in this review) were identified, all but one occurred in the setting of known immunosuppression. LIMITATIONS: The primary limitation was the exclusion of studies that did not fulfill the stringent review criteria. We excluded reports with only a clinical diagnosis of BKVN, such as those with viruria and/or viremia without biopsy. CONCLUSIONS: As of May 2018, there are 65 reported cases of BKVN in native kidneys. This represents the most comprehensive description of biopsy-proven BKVN in native kidneys to date. Evaluation for BK nephropathy should be considered in immunocompromised patients who exhibit unexplained renal failure.

A clone-directed approach may improve diagnosis and treatment of proliferative glomerulonephritis with monoclonal immunoglobulin deposits.

The optimal treatment for the monoclonal gammopathies of renal significance is not known, but there is consensus among experts that treatment should be specific for the underlying clone. The majority of patients with proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) do not have an identifiable clone, and prior studies have found poor renal outcomes for patients with PGNMID treated with a variety of regimens. Here we present a retrospective case series of 19 patients with PGNMID with a more uniform, clone-directed approach. A circulating paraprotein was detected in 37% of patients, and the overall clone detection rate was 32%. Treatment was directed at the underlying clone or, for patients without a detectable clone, empirically prescribed to target the hypothesized underlying clone. Of the 16 patients who underwent treatment, the overall renal response rate was 88%, and 38% of patients experienced complete renal response (proteinuria reduction to under 0.5 gm/24 hours) with initial treatment. All patients were End Stage Renal Disease-free at last follow-up (median 693 days after diagnosis), and treatment was well tolerated. Thus, a clone-directed approach may lead to novel, targeted treatment strategies that could significantly improve outcomes for patients with PGNMID.

Risk of complications with use of aspirin during renal biopsy: A systematic review.

BACKGROUND: Bleeding is a well-known complication of percutaneous renal biopsy (PRB). Thus, antiplatelet agents are routinely held for most patients undergoing elective PRB to decrease bleeding risk. MATERIALS AND METHODS: In this systematic review, we examine the association between antiplatelet use and bleeding during PRB. MEDLINE and EMBASE were searched from inception to December 2016 using terms that included "renal biopsy", "antiplatelet","aspirin", and "bleeding". Guidelines and systematic reviews were identified primarily through large databases, including the National Guideline Clearinghouse and Cochrane Database of Systematic Reviews. Two authors independently screened the results, and appraised and graded the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: Out of 371 guidelines, 40 systematic reviews, and 709 primary studies originally identified, 4 guidelines, 1 systematic review, and 2 primary studies met inclusion criteria. The guidelines recommend halting aspirin for elective PRB. The systematic review found no difference in major outcomes for PRB in patients for whom aspirin was continued versus halted, but was of low quality. The 2 nonrandomized primary studies in PRB patients managed with and without aspirin found no difference in major bleeds but a higher risk of minor bleeds. CONCLUSIONS: There is low-quality evidence on the effect of aspirin on bleeding risk from PRB. It is reasonable to discontinue aspirin 7 - 10 days prior to nonemergent biopsies, in accordance with guidelines. Given the results from the primary studies, it is reasonable to perform randomized controlled trials to obtain high-quality evidence to inform clinical practice.
.

New insights into the pathogenesis and treatment of heavy chain deposition disease.

Heavy chain deposition disease is defined by the presence of tissue deposits of truncated monoclonal Ig heavy chains, usually associated with an underlying plasma cell clone. In this issue of Kidney International, Bridoux et al. described the clinical, histologic, and molecular characterization of 15 patients with heavy chain deposition disease, which is the largest case series to date. Notable findings included the frequent presence of C3 deposits and hypocomplementemia, the uniform finding of truncated heavy chains with the deletion in the heavy chain constant region 1, and the common occurrence of an abnormal serum-free κ:λ ratio, despite the absence of light-chain tissue deposition. Importantly, this study showed that clinical outcomes are improved significantly with modern antiplasma cell therapies such as bortezomib.

New-onset hepatitis C virus-associated glomerulonephritis following sustained virologic response with direct-acting antiviral therapy
.

Glomerulonephritis (GN) is an important extra-hepatic manifestation of infection with hepatitis C virus (HCV). HCV-associated GN occurs due to HCV-induced lymphoproliferation, leading to the generation of pathogenic immune complexes, including complexes containing cryoglobulins. The management of HCV-associated extra-hepatic disease is focused on viral eradication, with direct-acting antiviral agents leading to high rates of sustained virologic remission. There have been a few reports of relapsing cryoglobulinemic vasculitis after sustained virologic remission was achieved with interferon-based therapies. This report presents two cases of new-onset HCV-associated GN that occurred after sustained virologic response was achieved with direct-acting antiviral (DAA) therapy.
.