Supportive Management of IgA Nephropathy With Renin-Angiotensin Blockade, the AIIMS Primary IgA Nephropathy Cohort (APPROACH) Study

Exploring Novel Adverse Events of Nefecon

Introduction

Nefecon, the first innovative drug approved by both the US Food and Drug Administration (FDA) and European Medicines Agency for IgA nephropathy (IgAN), lacked comprehensive real-world assessments of its adverse events (AEs).

Methods

We leveraged postmarketing data of Nefecon from the US FDA Adverse Event Reporting System (FAERS), employing disproportionate analysis (DPA) to detect positive signals at the system organ class (SOC) and preferred terms (PTs) levels. Duplicate AEs related to budesonide and those previously reported in studies were excluded through the use of the Medical Dictionary of Regulatory Activities (MedDRA). Our analysis encompassed time-to-onset (TTO), Weibull shape parameter (WSP) evaluation, cumulative incidence, clinical prioritization evaluation, and subgroup analysis based on gender and age.

Results

A total of 1515 individuals with IgAN were included. Five positive SOC signals and 23 positive PT signals were identified, including 4 PTs (asthenia, malaise, product dose omission issue, and anxiety) representing novel AEs newly identified in this study. None of the positive PTs were classified as high clinical priority, with only acne, hypertension, swelling face, and weight increased considered as moderate clinical priority events. The median time to TTO was 31 days. All WSP test results indicated an early failure type profile. Lastly, subgroup analysis provided further insights into the relative risk of specific AEs.

Conclusion

Nefecon demonstrates a favorable safety profile, with no high-priority clinical events identified. The identification of novel AEs and subgroup-specific relative high-risk events fills a gap in existing studies and offers valuable insights for early clinical vigilance.

Contemporary review of IgA nephropathy

IgA nephropathy (IgAN) is considered the most common primary glomerulonephritis worldwide with a predilection for Asian-Pacific populations and relative rarity in those of African descent. Perhaps 20%-50% of patients progress to kidney failure. The pathogenesis is incompletely understood. Mesangial deposition of immune complexes containing galactose-deficient IgA1 complexed with anti-glycan IgG or IgA antibodies results in mesangial cell activation and proliferation, inflammatory cell recruitment, complement activation, and podocyte damage. Diagnosis requires a biopsy interpreted by the Oxford criteria. Additional pathologic features include podocytopathy, thrombotic microangiopathy, and C4d staining. Biomarkers predicting adverse outcomes include proteinuria, reduced GFR, hypertension, and pathology. Acceptable surrogate endpoints for therapeutic trials include ongoing proteinuria and rate of eGFR decline. The significance of persisting hematuria remains uncertain. The mainstay of therapy is supportive, consisting of lifestyle modifications, renin-angiotensin inhibition (if hypertensive or proteinuric), sodium-glucose-transporter 2 inhibition (if GFR reduced or proteinuric), and endothelin-receptor antagonism (if proteinuric). Immunosuppression should be considered for those at high risk after maximal supportive care. Corticosteroids are controversial with the most positive results observed in Chinese. They carry a high risk of serious side effects. Similarly, mycophenolate may be most effective in Chinese. Other immunosuppressants are of uncertain benefit. Tonsillectomy appears efficacious in Japanese. Active areas of investigation include B-cell inhibition with agents targeting the survival factors BAFF and APRIL and complement inhibition with agents targeting the alternate pathway (Factors B and D), the lectin pathway (MASP-2), and the common pathway (C3 and C5). Hopefully soon, the who and the how of immunosuppression will be clarified, and kidney failure can be forestalled.

Urinary exosomal mRNAs as biomarkers for predicting the therapeutic effect of renin-angiotensin system inhibitors in IgA nephropathy patients

BACKGROUND

Renin-angiotensin system inhibitors (RASi) treatment is the basic therapy for IgA nephropathy (IgAN) patients. However, there is few of biomarker that can predict the efficacy of RASi. This study aimed to find urinary exosomal mRNAs related to the therapeutic effect of RASi in the treatment of proteinuria in IgAN patients.

METHODS

We divided IgAN patients in screening cohort into A1 (proteinuria increase at 3 months), B1 (proteinuria decrease less than 50 % at 3 months), C1 (proteinuria decrease more than 50 % at 3 months) groups according to changes of proteinuria after treatment. The urinary exosomes were collected before biopsy, RNAs were extracted and analyzed with the microarray assay. The candidate genes were screened by differentially expressed genes (DEGs) analysis and then validated by quantitative real-time polymerase chain reaction (qPCR) in a validation cohort. A receiver operating characteristic (ROC) curve was used to evaluate gene performance in predicting therapeutic effect on RASi reducing proteinuria in IgAN patients.

RESULTS

ECE1 and PDE1A mRNAs were significantly different among the three groups, and were gradually decreased among A1, B1 and C1 groups. In the validation cohort, the level of urinary exosomal ECE1 and PDE1A mRNAs were also significantly lower in A2 group compared with C2 group(ECE1, P < 0.001;PDE1A, P < 0.01). Besides, the level of ECE1 mRNA was also lower in B2 group compared with C2 group (P < 0.01). The ROC curve verified that urinary exosomal ECE1 and PDE1A gene level predicted RASi efficacy in IgAN patients with area under curve (AUC) 0.68 and 0.63 respectively.

CONCLUSION

Urinary exosomal ECE1 and PDE1A mRNAs expression can serve as potential biomarkers for predicting the RASi efficacy to reduce proteinuria in IgAN patients.

Sparsentan ameliorates glomerular hypercellularity and inflammatory-gene networks induced by IgA1-IgG immune complexes in a mouse model of IgA nephropathy

IgA nephropathy (IgAN) is characterized by glomerular deposition of immune complexes (ICs) consisting of IgA1 with O-glycans deficient in galactose (Gd-IgA1) and Gd-IgA1-specific IgG autoantibodies. These ICs induce kidney injury, and in the absence of disease-specific therapy, up to 40% of patients with IgAN progress to kidney failure. IgA1 with its clustered O-glycans is unique to humans, which hampered development of small-animal models of IgAN. Here, we used a model wherein engineered ICs (EICs) formed from human Gd-IgA1 and recombinant human IgG autoantibody are injected into nude mice to induce glomerular injury mimicking human IgAN. In this model, we assessed the protective effects of sparsentan, a single-molecule dual endothelin angiotensin receptor antagonist (DEARA) versus vehicle on EIC-induced glomerular proliferation and dysregulation of gene expression in the kidney. Oral administration of sparsentan (60 or 120 mg/kg daily) to mice intravenously injected with EIC attenuated the EIC-induced glomerular hypercellularity. Furthermore, analysis of changes in the whole kidney transcriptome revealed that key inflammatory and proliferative biological genes and pathways that are upregulated in this EIC model of IgAN were markedly reduced by sparsentan, including complement genes, integrin components, members of the mitogen-activated protein kinase family, and Fc receptor elements. Partial overlap between mouse and human differentially expressed genes in IgAN further supported the translational aspect of the immune and inflammatory components from our transcriptional findings. In conclusion, our data indicate that in the mouse model of IgAN, sparsentan targets immune and inflammatory processes leading to protection from mesangial hypercellularity.NEW & NOTEWORTHY The mechanisms by which deposited IgA1 immune complexes cause kidney injury during early phases of IgA nephropathy are poorly understood. We used an animal model we recently developed that involves IgA1-IgG immune complex injections and determined pathways related to the induced mesangioproliferative changes. Treatment with sparsentan, a dual inhibitor of endothelin type A and angiotensin II type 1 receptors, ameliorated the induced mesangioproliferative changes and the associated alterations in the expression of inflammatory genes and networks.

A new alternative: inhibiting complement activation in patients with IgA nephropathy

Mesangial complement C3 deposits, reflecting alternative and possibly lectin pathway activation, are characteristic in biopsies of patients with IgA nephropathy (IgAN). A recent randomized controlled trial tested the efficacy and safety of iptacopan, a factor B inhibitor, in patients with IgAN. Iptacopan dose-dependently reduced proteinuria, and there was a pronounced decrease of urinary C5b-9. This offers the perspective of "personalizing" therapy, which would be a unique feature of this novel approach to IgAN. A phase III clinical trial (APPLAUSE-IgAN) is ongoing.

Optimal Conservative Therapy Use among Adult Cure Glomerulonephropathy Participants with IgA Nephropathy

Optimal supportive therapy with BP and proteinuria control is pivotal in treating patients with IgA nephropathy. Suboptimal treatment of hypertension and proteinuria persisted in many patients with IgA nephropathy in the Cure Glomerulonephropathy Network study. Many patients had above-target proteinuria despite optimal BP control and may benefit from novel therapies or clinical trials.

Novel agents for treating IgA nephropathy

PURPOSE OF REVIEW

In the past, the treatment of IgA nephropathy (IgAN), which is the most common glomerulonephritis worldwide, mostly relied on blockade of the renin-angiotensin system as a central component of so-called supportive therapy as well as on high-dose systemic corticosteroid therapy.

RECENT FINDINGS

The supportive treatment arm has been expanded by the addition of sodium-glucose cotransporter-2 inhibitors, hydroxychloroquine, and, most recently, endothelin A receptor blockers. Treatment with high-dose systemic corticosteroids has become more controversial, with some studies observing no benefit and others documenting the protection of kidney function. However, all recent studies on systemic corticosteroids consistently found significant toxicity. An important novel approach to IgAN, therefore, is therapy with a targeted release formulation of budesonide with preferential release in the distal small intestine, given the mounting evidence for a gut-kidney axis in the pathophysiology of IgAN. In addition, emerging new therapeutic options include a variety of complement inhibitors as well as agents targeting B-cell proliferation and differentiation.

SUMMARY

In recent years, IgAN has become the focus of a considerable number of clinical studies that will significantly advance the development of new therapy strategies.

Comparison between hydroxychloroquine and systemic corticosteroids in IgA nephropathy: a two-year follow-up study

BACKGROUND

Hydroxychloroquine (HCQ) is recommended as a treatment for IgA nephropathy (IgAN) to control proteinuria. The long-term effects of HCQ compared to systemic corticosteroid therapy remain unclear.

METHODS

We conducted a retrospective case‒control study at Peking University First Hospital. Thirty-nine patients with IgAN who received HCQ for at least 24 months without corticosteroids (CSs) or other immunosuppressive agents were included. Thirty-nine matched patients who received systemic CS therapy were selected using propensity score matching. Clinical data over a 24-month period were compared.

RESULTS

In the HCQ group, the level of proteinuria decreased from 1.72 [1.44, 2.35] to 0.97 [0.51, 1.37] g/d (-50.5 [-74.0, -3.4] %, P < 0.001) at 24 months. A significant decline in proteinuria was also found in the CS group, but no significant differences were found between the HCQ group and CS group in the levels of proteinuria (0.97 [0.51, 1.37] vs. 0.53 [0.25, 1.81] g/d, P = 0.707) and change rates (-50.5% [-74.0%, -3.4%] vs. -63.7% [-78.5%, -24.2%], P = 0.385) at 24 months. In addition, the decline rates of eGFR between the HCQ and CS groups were comparable (-7.9% [-16.1%, 5.8%] vs. -6.6% [-14.9%, 5.3%], P = 0.758). More adverse events were observed in the CS group.

CONCLUSIONS

Long-term use of HCQ can maintain stable renal function with minimal side effects. In patients who cannot tolerate corticosteroids, HCQ might be an effective and safe supportive therapy for IgAN.

Emerging role of monoclonal antibodies in the treatment of IgA nephropathy

INTRODUCTION

IgA nephropathy is the most common primary glomerulonephritis worldwide. Immune complexes, composed of galactose-deficient IgA1 and Gd-IgA1 autoantibodies, are deposited in the mesangial area of the glomeruli where they induce complement-mediated inflammation. This may result in the reduced kidney function which can progress to end stage kidney disease.Treatment options are very limited. Treatments which directly affect the formation of pathogenic Gd-IgA1 antibodies and anti-Gd-IgA1 antibody-containing immune complexes are needed.

AREAS COVERED

This article reviews potential therapies, namely monoclonal antibodies, that may affect the main axis of pathogenesis of IgA nephropathy with discussion of their potential impact on the outcome of IgAN. PubMed was used to perform the literature search which included papers on "treatment of IgA nephropathy"combined with "biological therapy", or "monoclonal antibodies, atacicept, sibeprenlimab, rituximab, felzartamab, narsoplimab, iptacopan" published up until 2023.

EXPERT OPINION

New treatment options are aimed at the immunopathogenesis of IgAN including depletion or modulation of Gd-IgA1 producing B cells, plasma cells, alternate or lectin pathway of complement. Monoclonal antibodies may target both B cells and T cells and also the factor needed for their activation and survival, e.g BAFF or APRIL.

Corticosteroid Therapy in Immunoglobulin A Nephropathy: A Friend or Foe?

BACKGROUND

The administration of corticosteroids in addition to supportive care to delay progressive immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis worldwide, remains controversial. This is partly due to the paucity of well-designed randomized controlled trials and well-known corticosteroid-related side effects. As a result, clinical equipoise in corticosteroid therapy exists depending on geographical regions and the clinician's preference.

SUMMARY

Better understanding around the pathogenesis of IgAN has prompted several clinical trials exploring the effects of immunosuppressive agents including corticosteroids. Earlier studies of corticosteroids were limited by suboptimal study designs, inadequate implementation of standard of care, and inconsistent adverse event data collection. Two well-designed, adequately powered, multi-centre randomized controlled trials, the STOP-IgAN and TESTING studies, have reported contrasting kidney outcomes that have further fuelled the clinical conundrum regarding the efficacy of corticosteroids. Both studies independently reported greater adverse events with corticosteroids. A novel targeted release formulation of budesonide, which has been hypothesized to reduce the adverse events associated with systemic corticosteroids, has shown promising results in the Phase 3 NefigaRD trial. Studies of treatments targeting B cells and the complement cascade are currently underway, and early data appear encouraging. This review provides an overview of the current literature around the understanding of the pathomechanisms and benefits and harm of corticosteroid use in IgAN.

KEY MESSAGES

Recent evidence suggests the use of corticosteroids in a selected cohort of people with IgAN at high risk of disease progression can improve kidney outcomes but comes with an associated risk of treatment-related adverse events, particularly with higher doses. Management decisions should therefore follow an informed patient-clinician discussion.

Visit-to-visit variability in blood pressure and kidney disease progression in IgA nephropathy

Background

The visit-to-visit variability (VVV) in blood pressure (BP) is an important risk factor for stroke and coronary heart disease and may also be associated with kidney damage and the development of chronic kidney disease (CKD). Data on the association between VVV in BP and the risk of CKD progression among patients with immunoglobulin A nephropathy (IgAN) are limited. We aimed to evaluate the relationships of VVV in BP with the progression of IgAN.

Methods

We assessed 1376 patients with IgAN at Peking University First Hospital. The main VVV in BP was expressed as the standard deviation (SD), coefficient of variation (CV) and average real variability (ARV). The associations of variability in BP with composite kidney disease progression events, defined as a 50% decline in estimated glomerular filtration rate (eGFR) and kidney failure, were examined using Cox models.

Results

During a median follow-up of 44.1 months (interquartile range 23.0–76.7), 247 (18.0%) patients experienced composite kidney disease progression events. With a higher SD in systolic BP (SBP) values, the risk of kidney disease progression events increased {hazard ratio [HR] 1.07 [95% confidence interval (CI) 1.03–1.11]; P < .001} after maximal adjustment, including baseline SBP and mean SBP during the first 12-month period. Using the first quartile of SD SBP values as the reference, the risk of composite kidney disease progression events was higher among patients with higher SD SBP values; the HR was 2.12 (95% CI 1.31–3.44) in the highest quartile (P for trend < .001). A similar trend could be observed when analysing the SD of diastolic BP, but the risk was not significantly increased. The associations were similar when analysed with the CV and ARV.

Conclusion

SBP variability was significantly associated with kidney disease progression in IgAN.

Plasma exosomal IRAK1 can be a potential biomarker for predicting the treatment response to renin-angiotensin system inhibitors in patients with IgA nephropathy

Background

Renin-angiotensin system inhibitors (RASi) are the first choice and basic therapy for the treatment of IgA nephropathy (IgAN) with proteinuria. However, approximately 40% of patients have no response to RASi treatment. The aim of this study was to screen potential biomarkers for predicting the treatment response of RASi in patients with IgAN.

Methods

We included IgAN patients who were treatment-naive. They received supportive treatment, including a maximum tolerant dose of RASi for 3 months. According to the degree of decrease in proteinuria after 3 months of follow-up, these patients were divided into a sensitive group and a resistant group. The plasma of the two groups of patients was collected, and the exosomes were extracted for high-throughput sequencing. The screening of hub genes was performed using a weighted gene co-expression network (WGCNA) and filtering differentially expressed genes (DEGs). We randomly selected 20 patients in the sensitive group and 20 patients in the resistant group for hub gene validation by real-time quantitative polymerase chain reaction (qRT−PCR). A receiver operating characteristic (ROC) curve was used to evaluate hub genes that predicted the efficacy of the RASi response among the 40 validation patients.

Results

After screening 370 IgAN patients according to the inclusion and exclusion criteria and the RASi treatment response evaluation, there were 38 patients in the sensitive group and 32 patients in the resistant group. IRAK1, ABCD1 and PLXNB3 were identified as hub genes by analyzing the high-throughput sequencing of the plasma exosomes of the two groups through WGCNA and DEGs screening. The sequencing data were consistent with the validation data showing that these three hub genes were upregulated in the resistant group compared with the sensitive group. The ROC curve indicated that IRAK1 was a good biomarker to predict the therapeutic response of RASi in patients with IgAN.

Conclusions

Plasma exosomal IRAK1 can be a potential biomarker for predicting the treatment response of RASi in patients with IgAN.

New Treatment Strategies for IgA Nephropathy: Targeting Plasma Cells as the Main Source of Pathogenic Antibodies

Immunoglobulin A nephropathy (IgAN) is a rare autoimmune disorder and the leading cause of biopsy-reported glomerulonephritis (GN) worldwide. Disease progression is driven by the formation and deposition of immune complexes composed of galactose-deficient IgA1 (Gd-IgA1) and Gd-IgA1 autoantibodies (anti-Gd-IgA1 antibodies) in the glomeruli, where they trigger complement-mediated inflammation that can result in loss of kidney function and end-stage kidney disease (ESKD). With the risk of progression and limited treatment options, there is an unmet need for therapies that address the formation of pathogenic Gd-IgA1 antibody and anti-Gd-IgA1 antibody-containing immune complexes. New therapeutic approaches target immunological aspects of IgAN, including complement-mediated inflammation and pathogenic antibody production by inhibiting activation or promoting depletion of B cells and CD38-positive plasma cells. This article will review therapies, both approved and in development, that support the depletion of Gd-IgA1-producing cells in IgAN and have the potential to modify the course of this disease. Ultimately, we propose here a novel therapeutic approach by depleting CD38-positive plasma cells, as the source of the autoimmunity, to treat patients with IgAN.

The comprehensive analysis of clinical trials registration for IgA nephropathy therapy on ClinicalTrials.gov

Objectives

IgA Nephropathy (IgAN) is common chronic kidney disease with a high incidence. This study aims to analyze comprehensively therapeutic clinical trials for IgAN registered on ClinicalTrials.gov.

Methods

Therapeutic trials for IgAN registered on ClinicalTrials.gov. up to 15 August 2021 were obtained. The general characteristics, features of experimental design, treatment strategies, and some main inclusion criteria and outcome measures were accessed.

Results

A total of 104 therapeutic clinical trials for IgAN were extracted on ClinicalTrials.gov up to 15 August 2021. Most of these trials explored the treatment for primary IgAN confirmed by renal biopsy in adults. Only 9% of all selected trials had results. Forty-five percent of trials recruited 50 or fewer participants, and 73% were adults or older adults. 99% of trials were interventional studies, and of all the interventional trials, 70% of trials were randomized, and 68% exercised a parallel assignment of intervention model. Immunosuppression was the most studied for the treatment of IgAN. Moreover, many novel agents had been increasingly studied in recent years. Furthermore, the inclusion criteria and primary outcome measures in these trials were diverse, and the level of proteinuria and change of proteinuria levels were the most used as inclusion criteria and primary outcome, respectively.

Conclusions

The majority of therapeutic trials for IgAN were randomized, none masking and parallel-assignment interventional studies, primarily recruiting adult patients as research subjects. These trials had relatively small sample sizes and short observation. Thus, more large-scale, multicenter, and randomized controlled trials are still needed to improve the management for IgAN.

Factors associated with the progression of mesangial lesions in IgA nephropathy: A comparative analysis of renal re-biopsies

OBJECTIVES

IgA nephropathy (IgAN) is the most common primary glomerular disease, and is the leading cause of chronic renal failure. Because mesangial lesions are the main pathological changes seen in IgAN, we investigated factors associated with the progression of mesangial lesions in IgAN.

METHODS

We enrolled participants with IgAN who underwent repeat renal biopsies. Based on the progression of mesangial proliferative lesions, the participants were divided into progressive and stable groups. The progression group included participants with a ratio of mesangial cell proliferation score ≥ 1.1 (i.e., proliferation of > 10%) in the second biopsy specimen compared to the first biopsy specimen. The stable group included participants who did not fulfill the aforementioned criteria. We recorded the laboratory parameters, expression of renin-angiotensin system (RAS) receptors (angiotensin II type 1 receptor [AT1R], angiotensin II type 2 receptor [AT2R], Mas receptor [MasR], and the Mas-related G protein-coupled receptor, member D [MrgD]) and mesangial matrix proteins (collagen [Col] IV, fibronectin [FN] and laminin) at the first and second renal biopsies, and the use of immunosuppressive therapy and/or RAS blockers after the first biopsy.

RESULTS

We enrolled 24 patients with IgAN who underwent repeat renal biopsies. Half of patients showed progression of mesangial lesions on repeat renal biopsy after a median of 4.3 (1-6) years. The progression group had significantly higher expression levels of AT1R and mesangial matrix proteins (Col IV and FN), and significantly lower expression of AT2R and MasR, compared to the stable group. Multivariate analysis showed that the use of RAS blockers (hazard ratio [HR], 0.27; 95% CI, 0.08-0.97; p < 0.05) and the level of proteinuria (HR, 1.8; 95% CI, 1.04-3.12; p < 0.05) were associated with progression of mesangial lesions. Additionally, the progression group exhibited a more rapid decline of renal function compared to the stable group (0.38 and 0.012 ml/min/1.73 m²/month, respectively; p = 0.004).

CONCLUSIONS

Continuous activation of the intrarenal RAS and massive proteinuria correlate with histological progression of mesangial lesions in IgAN patients, which may further accelerate the deterioration of renal function.