A Randomized, Controlled Trial of Rituximab in IgA Nephropathy with Proteinuria and Renal Dysfunction

Efficacy and safety of telitacicept in IgA nephropathy: a real-world study

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerular disease in the world, and specific therapeutic methods for IgAN are limited. Telitacicept is a humanized fusion protein composed of a transmembrane activator and calcium-modulating cyclophilin ligand interactor receptor and human IgG.

AIM

To evaluate the efficacy and safety of telitacicept in adult patients with IgAN in a real-world study.

METHODS

Biopsy-proven IgAN patients with 24-hour proteinuria greater than 0.5 g/d who received 240 mg telitacicept weekly were recruited for this study and 1:1:1 matched with patients who received supportive treatment only or immunosuppressive treatment by propensity score matching. The primary outcome was the change from baseline in 24-hour proteinuria over the 3-month follow-up.

RESULTS

Twenty-one patients in each group were enrolled. Telitacicept reduced median proteinuria by 0.72 g/d (54.6%) from baseline, compared with a reduction of 0.18 g/d (20%) in the supportive treatment group and 1.12 g/d (72.1%) in the immunosuppressive treatment group. Preserved eGFR levels were observed in the telitacicept group, whereas eGFR levels decreased in the other two groups. No serious adverse events were observed in the telitacicept treatment group.

CONCLUSION

Telitacicept may be an effective treatment for IgAN patients by reducing proteinuria and preserving eGFR, and showed a favorable safety profile.

Tailored management strategies for IgA nephropathy based on clinical presentations

The treatment landscape for immunoglobulin A nephropathy is rapidly evolving with the introduction of novel therapies targeting diverse disease pathways. Some have already been approved in different countries, while others are under investigation in randomized controlled trials (RCTs) with encouraging results. However, almost all performed RCTs have included only patients with refractory non-nephrotic proteinuria and preserved renal function. Other clinical presentations (rapidly progressive forms, malignant hypertension, thrombotic microangiopathy, nephrotic syndrome) have received less attention and are systematically excluded from RCTs. In contrast, certain aspects, such as the impact of haematuria or management in special populations (e.g. pregnant patients or transplant recipients), remain underexplored. This review proposes therapeutic algorithms to guide treatment decisions in different clinical scenarios while highlighting gaps in current research.

Successful treatment of MPO-ANCA positive crescentic IgA nephropathy/IgA vasculitis with nephritis potentially triggered by a COVID-19 vaccine in a young adult female using corticosteroids, rituximab, and avacopan

An 18-year-old female presented with palpable purpura nine months before her hospital admission, which first appeared 1 month after receiving a COVID-19 vaccine and recurred intermittently. One month prior to admission, she developed macrohematuria, abdominal pain, and a loss of appetite. Occult blood in urine had been noted during high school health check-ups. Upon admission, she continued to have macrohematuria, along with renal dysfunction and a nephritic urinalysis, serum myeloperoxidase-anti-neutrophil cytoplasmic antibodies (MPO-ANCA) positivity. A renal biopsy revealed crescentic glomerulonephritis with mesangial and endocapillary hypercellularity, and dominant IgA deposition and electron-dense deposits in the mesangial regions. The diagnosis was IgA nephropathy (IgAN) or IgA vasculitis with nephritis (IgAVN), with a possible overlap of MPO-ANCA-associated glomerulonephritis. Treatment began with methylprednisolone pulse therapy and prednisolone. After the diagnosis, rituximab (RTX) and avacopan were added to the regimen. Within two months, renal function, hematuria, and MPO-ANCA levels had normalized, and proteinuria was almost fully resolved by 13 months. If IgAN/IgAVN and ANCA-associated vasculitis were indeed triggered by the COVID-19 vaccination in this case, it is plausible that both conditions share similar pathologic mechanisms. This case emphasizes the need for a reliable laboratory method to detect pathogenic ANCA to guide both induction and maintenance therapy. Further investigation into the effectiveness of the ANCA-associated glomerulonephritis treatment protocol including corticosteroids, RTX, and avacopan in managing crescentic IgAN/IgAVN could offer valuable insights into improving patient care.

Treatment of patients with IgA nephropathy: a call for a new paradigm

IgA nephropathy (IgAN), the world's most common primary glomerular disease, carries a significant lifetime risk for kidney failure as well as an enormous socioeconomic burden. In the past, studies in patients with IgAN largely focused on optimizing so-called supportive care, that is, blockade of the renin-angiotensin system, blood pressure control, and lifestyle modifications. The effectiveness of immunosuppressive measures, particularly high-dose corticosteroid therapy, has been reported variably, but there is considerable evidence for an increase in serious adverse effects with such therapies. This disappointing situation has changed dramatically with a better understanding of the pathogenesis of IgAN, and with regulatory agencies accepting changes in proteinuria and the estimated glomerular filtration rate loss or slope over 2 to 3 years as surrogate outcome markers. A multitude of new therapies are now being evaluated in IgAN, and several drugs, such as sodium-glucose transporter-2 inhibitors, sparsentan (a dual endothelin-1 and angiotensin II receptor blocker), nefecon (a targeted release formulation of budesonide), and iptacopan (a complement factor B inhibitor), have been approved, with more to come in the next few years. In this review, we propose a new treatment paradigm that combines therapies with different mechanisms of action to target the immune components and the chronic kidney disease components of IgAN in parallel to preserve long-term kidney survival.

Telitacicept as an alternative to non-steroidal immunosuppressive therapies in the treatment of myasthenia gravis: a study on clinical efficacy and steroid-sparing effect

Introduction

Myasthenia Gravis (MG) is an autoimmune disorder characterized by impaired neuromuscular junction (NMJ) transmission. Current treatments for MG include steroids and nonsteroidal immunosuppressive therapies (NSISTs). However, approximately 20% of patients show a poor response to these therapies, which are often associated with significant side effects. Telitacicept, a novel recombinant fusion protein targeting the BAFF/APRIL pathway, has shown promise in treating autoimmune diseases, including MG.

Methods

This retrospective study compared the efficacy of telitacicept monotherapy (10 patients) to NSISTs (16 patients) and sequential therapy (6 patients) in managing Myasthenia Gravis (MG) at The First Affiliated Hospital of Wenzhou Medical University (July 2020-November 2024). The primary endpoint was the time to achieve minimal symptom expression (MSE), and secondary endpoint was the change in the mean daily prednisone dosage from baseline to month 4.

Results

Among telitacicept-treated patients, 80% achieved MSE within 4 months, with a significant reduction in mean daily dose of prednisone (from 45.00 mg to 6.25 mg, P < 0.001). In contrast, only 12.5% of the NSISTs group achieved MSE, with no significant change in mean daily dose of prednisone (P = 0.091). The sequential therapy group (efgartigimod followed by telitacicept) maintained stable disease conditions.

Conclusion

Telitacicept is effective in inducing MSE rapidly and offers a steroid-sparing effect, making it a promising alternative to traditional NSISTs with fewer side effects in MG patients.

Successful outcome of a refractory IgA vasculitis nephritis in children treated with telitacicept

IgA vasculitis (IgAV) is the most prevalent form of vasculitis in children. While most cases of IgAV present with mild clinical symptoms and generally have a favorable prognosis, some children with IgAV nephritis may experience persistent heavy proteinuria, which is at risk of progressing to end-stage renal disease. Despite the administration of various immunosuppressive agents, treatment outcomes for these children are often suboptimal. We report the case of an 8-year-and-four-month-old girl who initially presented with rashes on both lower limbs for a duration of four days and abdominal pain persisting for two days. Renal biopsy subsequently confirmed a diagnosis of IgAV nephritis, specifically type IIIb. Despite undergoing treatment with methylprednisolone sodium succinate, cyclophosphamide, mycophenolate mofetil, leflunomide, rituximab, dapagliflozin, and other medications for over two years, her urinary protein levels remained at least 1000 mg/24 h. One month after initiating treatment with telitacicept, the patient's urinary protein levels decreased, and two months later, they became negative. Notably, even after discontinuing immunosuppressants and glucocorticoids, the girl achieved sustained clinical remission. This case serves as a valuable clinical reference for the use of telitacicept in the treatment of refractory IgAV nephritis.

IgA class-switched CD27-CD21+ B cells in IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is characterized by the production of galactose-deficient IgA1 (GdIgA1) antibodies. As the source of pathogenic antibodies, B cells are central to IgAN pathogenesis, but the B cell activation pathways as well as the potential B cell source of dysregulated IgA secretion remain unknown.

METHODS

We carried out flow cytometry analysis of peripheral blood B cells in patients with IgAN and control subjects with a focus on IgA-expressing B cells to uncover the pathways of B cell activation in IgAN and how these could give rise to pathogenic GdIgA1 antibodies.

RESULTS

In addition to global changes in the B cell landscape-expansion of naïve and reduction in memory B cells-IgAN patients present with an increased frequency of IgA-expressing B cells that lack the classical memory marker CD27, but are CD21+. IgAN patients furthermore have an expanded population of IgA+ antibody-secreting cells, which correlate with serum IgA levels. Both IgA+ plasmabalsts and CD27- B cells co-express GdIgA1. Implicating dysregulation at mucosal surfaces as the driver of such B cell differentiation, we found a correlation between lipopolysaccharide in the serum and IgA+CD27- B cell frequency.

CONCLUSION

We propose that dysregulated immunity in the mucosa may drive de novo B cell activation within germinal centres, giving rise to IgA+CD27- B cells and subsequently IgA-producing plasmablasts. These data integrate B cells into the paradigm of IgAN pathogenesis and allow further investigation of this pathway to uncover biomarkers and develop therapeutic interventions.

The road ahead: emerging therapies for primary IgA nephropathy

Primary IgA nephropathy (IgAN) is the most common form of primary glomerulopathy. A slowly progressive disease presenting in the young to middle-aged, most patients with reduced eGFR or proteinuria will progress to end-stage kidney disease (ESKD) in their lifetimes. The pathogenesis involves increased production of galactose-deficient IgA1 (Gd-IgA1) that forms immune complexes that deposit in the glomerulus, eliciting mesangial cell proliferation, inflammation, and complement activation. The backbone of therapy is supportive, including lifestyle modifications, strict blood pressure control, and renin-angiotensin system inhibition targeting proteinuria < 300 mg/day. Sodium-glucose transporter 2 inhibitors are indicated for persisting proteinuria or declining eGFR. Sparsentan is indicated for persisting proteinuria. Immunosuppression should be considered for all patients at risk for progression (persisting proteinuria and/or declining eGFR). To reduce Gd-IgA1 production, targeted-release budesonide is approved. Agents targeting B cell survival factors APRIL or BAFF/APRIL have significantly reduced Gd-IgA1 production and proteinuria in phase 2 trials but await phase 3 data for approval. To reduce inflammation, high-dose steroids are ineffective and toxic in Caucasian patients, although lower-dose regimens may be effective in Chinese patients. Complement inhibition is being actively studied. The factor B inhibitor iptacopan has conditional approval. The terminal pathway inhibitors cemdisiran and ravulizumab show promise in phase 2 studies. Our current approach for those requiring immunosuppression involves combining the reduction of Gd-IgA1 (nefecon) with suppressing the effects of inflammation (iptacopan). The optimal duration of such therapy is uncertain. Clearly, there is more to be learned with many trials underway.

IPNA clinical practice recommendations for the diagnosis and management of children with IgA nephropathy and IgA vasculitis nephritis

IgA nephropathy and IgA vasculitis with nephritis, albeit rare, represent two relatively frequent glomerular conditions in childhood. Compared to adults, pediatric IgA nephropathy has a more acute presentation, most frequently with synpharyngitic macrohematuria and histologically with more intense inflammation and less intense chronic damage. Management of these conditions is controversial and supported by little high-quality evidence. The paucity of evidence is due to the disease heterogeneity, its inter-ethnic variability, and the difficulty of extrapolating data from adult studies due to the peculiarities of the condition in children. IgA vasculitis with nephritis is a kidney manifestation of a systemic disorder, typical of the pediatric age, in which both the diagnosis of kidney involvement and its management are poorly defined, and an interdisciplinary approach is crucial. Both conditions can have a profound and long-lasting impact on kidney function and the global health of affected children. The International Pediatric Nephrology Association has therefore convened a diverse international group of experts from different disciplines to provide guidance on the recommended management of these conditions in children and to establish common definitions and define priorities for future high-quality, evidence-based collaborative studies for the benefit of children.

Patients With Immunoglobulin A Nephropathy Show Abnormal Frequencies of B Cell Subsets, Unconventional T Cells, and High Levels of Galactose-Deficient IgA1-Coated Gut Bacteria

Introduction

Mucosal inflammation is involved in the pathophysiology of immunoglobulin-A nephropathy (IgAN); however, peripheral immune phenotype analyses of patients with IgAN often do not include unconventional T cells, the major subset in mucosal immunity.

Methods

We measured serum total IgA, galactose-deficient IgA1 (gd-IgA1), secretory IgA (SIgA), B cell-activating factor (BAFF), and A proliferation-inducing ligand (APRIL) in 66 patients with IgAN and 30 healthy controls (HCs). We also quantified the total IgA and gd-IgA1 in stool supernatant along with the same coated on bacteria. In 35 patients and 14 controls, we performed extensive phenotyping using cytometry by Time-of-Flight (CyTOF) of circulating immune cells, including unconventional T cells (mucosal associated invariant T [MAIT] cells, γδ T, and natural killer [NK] T cells). The results were validated using RNAseq data from a larger cohort of 179 patients with IgAN, 140 patients with minimal change disease, and 91 HCs.

Results

Patients with IgAN had higher circulating levels of total IgA, gd-IgA1, and APRIL, and higher IgA and gd-IgA1-coated gut bacteria than controls, whereas serum levels of SIgA and BAFF did not differ between groups. Patients with IgAN showed more class-switched memory (CSM) and double negative (DN) B cells than controls. MAIT cells and γδ T cells were significantly lower, and CD4-CD8- NK T cells were significantly higher in patients with IgAN than in HCs. We validated the significant decrease in MAIT cells in an independent cohort of patients with IgAN.

Conclusion

The data indicate that patients with IgAN have increased circulating CSM and DN B cells associated with abnormal T cell immunity, involving defects in unconventional T cell frequency. This may suggest putative alterations at mucosal sites because of cell migration leading to altered IgA production.

Investigation of the Relationship Between Neutrophil/Lymphocyte, Platelet/Lymphocyte, IgA/C3, IgA/C4, and C3/C4 Ratios and Proteinuria in Patients With Immunoglobulin A (IgA) Nephropathy

Background Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease, characterized by IgA-containing immune complexes in the mesangium and mesangial cell proliferation. Proteinuria is a strong indicator of the progression of chronic kidney disease. This study aimed to evaluate the relationship between systemic inflammation markers, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), IgA/complement (C)3, IgA/C4, and C3/C4 ratios, and proteinuria in IgAN patients. Methods This retrospective study involved 38 patients diagnosed with IgAN between 2002 and 2011. We assessed various serum markers such as leukocyte count, NLR, PLR, C-reactive protein (CRP), C3, C4, IgA, and IgM, as well as proteinuria. The correlation between these markers and proteinuria was examined. Results The mean age of the patients was 37.8 ± 2 years, with 68.42% male. No significant correlation was found between the NLR and proteinuria (p=0.3) or CRP (p=0.3). However, a moderate positive correlation was observed between the NLR and sedimentation rate (R=0.38, p=0.07). Significant negative correlations were found between proteinuria and both urine pH (R=-0.5, p=0.002) and IgA/C4 ratio (R=-0.5, p=0.013). There were positive correlations between the PLR and C4 (R=0.45, p=0.02) and negative correlations between the PLR and IgA/C4 ratio (R=-0.56, p=0.003) and IgA/C4 and C3 (R=-0.48, p=0.008). No significant differences in proteinuria and leukocyte count were observed between the two sexes. Conclusion Although no significant relationship was found between the NLR, PLR, and proteinuria in IgAN, correlation between the IgA/C4 ratio and C4 warrants further investigations in larger studies.

The pathogenesis of IgA nephropathy and implications for treatment

IgA nephropathy (IgAN) is a common form of primary glomerulonephritis and represents an important cause of chronic kidney disease globally, with observational studies indicating that most patients are at risk of developing kidney failure within their lifetime. Several research advances have provided insights into the underlying disease pathogenesis, framed by a multi-hit model whereby an increase in circulating IgA1 that lacks galactose from its hinge region - probably derived from the mucosal immune system - is followed by binding of specific IgG and IgA antibodies, generating immune complexes that deposit within the glomeruli, which triggers inflammation, complement activation and kidney damage. Although treatment options are currently limited, new therapies are rapidly emerging that target different pathways, cells and mediators involved in the disease pathogenesis, including B cell priming in the gut mucosa, the cytokines APRIL and BAFF, plasma cells, complement activation and endothelin pathway activation. As more treatments become available, there is a realistic possibility of transforming the long-term outlook for many individuals with IgAN.

Rituximab as a first-line therapy in children with new-onset idiopathic nephrotic syndrome

Background

Idiopathic nephrotic syndrome (INS) in children, commonly treated with steroids, poses challenges due to associated side effects. Rituximab, known for its efficacy in reducing relapse frequency in difficult-to-treat cases, emerges a potential first-line therapy for pediatric new-onset INS.

Method

This is a single-center, retrospective, observational study to evaluate the efficacy and safety of rituximab as a first-line therapy for pediatric INS. The complete treatment strategy was weekly injections at a dose of 375 mg/m2 for four doses. Children with new-onset INS who received rituximab as a first-line monotherapy from 1 January 2022 to 31 December 2023 were included and followed until 31 May 2024.

Results

Seventeen patients (median age at diagnosis 4.8 years) were included. Twelve patients achieved complete remission within a median time of 19 days. Over a follow-up period ranging from 41 to 112 weeks, 11 patients maintained remission even after B-cell reconstitution, with one patient experiencing a relapse at 85 weeks. Three patients, who presented with hematuria, hypocomplementemia or renal injury at initial diagnosis, exhibited resistance to rituximab. No severe adverse events were noted.

Conclusion

Rituximab may be an effective and safe option as a first-line therapy for inducing and maintaining remission in newly diagnosed INS.

Efficacy and safety of rituximab in primary IgA nephropathy: a retrospective study

PURPOSE

The study aimed to evaluate the efficacy and safety of rituximab (RTX) in primary IgA nephropathy (IgAN).

METHODS

A retrospective review was conducted on the medical records of 22 patients diagnosed with primary IgAN who received RTX treatment. The clinical data, including blood tests, urine examinations and estimated glomerular filtration rate (eGFR), were analyzed at four time point: baseline, 3 months, 6 months and 12 months. Adverse events were also recorded.

RESULTS

Our study included 9 male and 13 female participants. The level of serum albumin significantly increased after three months with RTX applied (P < 0.01). Furthermore, we observed a significant reduction in microalbuminuria and urine albumin-to-creatinine ratio at twelve months (P < 0.01). However, there was no change in serum creatinine (P = 0.08), urinary red blood cell (P = 0.11) or eGFR (P = 0.09) during the course of one year. Two cases achieved complete remission, while eleven cases experienced partial remission, resulting in an overall remission rate of 50.0%. During the treatment period, three patients developed infections and two patients encountered infusion-related adverse reactions.

CONCLUSION

In our retrospective study, RTX demonstrated a significant improvement in serum albumin levels and a reduction in proteinuria among primary IgAN patients. Although no statistically significant difference was observed in terms of renal function, there was an observable trend towards improvement. Therefore, we propose that RTX may be an alternative treatment option for primary IgAN patients who cannot tolerate glucocorticoids or immunosuppressants.

What is new in the pathogenesis and treatment of IgA glomerulonephritis

Recently, new findings have been clarified concerning both pathogenesis and treatment of IgA nephritis. The four hits theory has been confirmed but several genetic wide association studies have allowed finding several genes connected with the pathogenesis of the disease. All these new genes apply to each of the four hits. Additionally, new discoveries concerning the microbiota and its connection with immune system and IgA generation have allowed finding out the role of the mucosa in IgA nephropathy pathogenesis. The IgA treatment is also changed included the future possibilities. The treatment of the chronic kidney disease, associated with the nephropathy, is mandatory, since the beginning of the disease. The classical immunosuppressive agents have poor effect. The corticosteroids remain an important cornerstone in any phase of the disease. More effect is related to the treatment of B cells and plasma cells. In particular, in very recent studies have been documented the efficacy of anti B cell-activating factor and anti A proliferation-inducing ligand agents. Most of these studies are to date in phase II/III. Finally, new agents targeting complement are arising. These agents also are still in randomized trials and act principally in hit 4 where the immunocomplexes in the mesangium activate the different pathways of the complement cascade.

A case diagnosed with IgA nephropathy during a complete remission of minimal change nephrotic syndrome treated with rituximab

We herein report a case of IgA nephropathy in a 20-year-old male who maintained a complete remission of minimal change nephrotic syndrome (MCNS) through the administration of rituximab (RTX). He was diagnosed with nephrotic syndrome at 4 years of age. After he relapsed frequently, he was diagnosed with MCNS at 8 years of age based on the findings of a kidney biopsy. At 13 years of age, RTX therapy was initiated to maintain a complete remission after steroid treatment. MCNS recurred twice, including the time in which the interval between the RTX administrations was long. Whenever he relapsed, remission induction was achieved using steroids, and remission maintenance was achieved using RTX. Five months after the 7th RTX administration, the serum IgA level started to increase. After the 9th RTX administration, he demonstrated microhematuria despite the urinary protein level indicating complete remission. At the 10th administration, the urinary protein and the red-blood cell casts were also observed. A renal biopsy was performed 84 months after the initial administration of RTX, and the patient was diagnosed with complications of IgA nephropathy. RTX is not considered to be a useful treatment for IgA nephropathy. The reasons for this are due to the fact that IgA1 does not decrease even following the administration of RTX, because B cells residing in the mucosa may not be deleted by RTX, and IgA production may also continue due to the presence of CD20- long-lived plasma cells. Even when administering RTX, if there are findings of glomerulonephritis on urine testing, the possibility of IgA nephropathy must be considered.

Development and Validation of a Machine Learning-Based Prognostic Model for IgA Nephropathy with Chronic Kidney Disease Stage 3 or 4

Introduction

Immunoglobulin A nephropathy (IgAN) patients with lower estimated glomerular filtration rate (eGFR) and higher proteinuria are at a higher risk for end-stage kidney disease (ESKD) and their prognosis is still unclear. We aim to develop and validate prognostic models in IgAN patients with chronic kidney disease (CKD) stage 3 or 4 and proteinuria ≥1.0 g/d.

Methods

Patients who came from Xijing Hospital, spanning December 2008 to January 2020 were divided into training and test cohorts randomly, with a ratio of 7:3, achieving ESKD and death as study endpoints. Created prediction models for IgAN patients based on 66 clinical and pathological characteristics using the random survival forests (RSF), survival support vector machine (SSVM), eXtreme Gradient Boosting (XGboost), and Cox regression models. The concordance index (C-index), integrated Brier scores (IBS), net reclassification index (NRI), and integrated discrimination improvement (IDI) were used to evaluate discrimination, calibration, and risk classification, respectively.

Results

A total of 263 patients were enrolled. The median follow-up time was 57.3 months, with 124 (47.1%) patients experiencing combined events. Age, blood urea nitrogen, serum uric acid, serum potassium, glomeruli sclerosis ratio, hemoglobin, and tubular atrophy/interstitial fibrosis were identified as risk factors. The RSF model predicted the prognosis with a C-index of 0.871 (0.842, 0.900) in training cohort and 0.810 (0.732, 0.888) in test cohort, which was higher than the models built by SSVM model (0.794 [0.753, 0.835] and 0.805 [0.731, 0.879], respectively), XGboost model (0.840 [0.797, 0.883] and 0.799 [0.723, 0.875], respectively) and Cox regression (0.776 [0.727, 0.825] and 0.793 [0.713, 0.873], respectively). NRI and IDI showed that the RSF model exhibited superior performance than the Cox model.

Conclusion

Our model introduced seven risk factors that may be useful in predicting the progression of IgAN patients with CKD stage 3 or 4 and proteinuria ≥1.0 g/d. The RSF model is applicable for identifying the progression of IgAN and has outperformed than SSVM, XGboost, and Cox models.

IgA Vasculitis (Henoch-Schönlein Purpura): An Update on Treatment

Objective: IgA vasculitis (IgAV), previously named as Henoch-Schönlein purpura, is the most frequent systemic vasculitis in children. In adults, IgAV is less common although it is associated with more severe disease. In fact, the frequency of glomerulonephritis (referred to as IgAV nephritis) in adults is higher than in children and tends to present more severely, with around 10-30% of those affected eventually progressing to end-stage renal disease. In this review, we describe the pathophysiology, main clinical features, diagnosis of the disease, and latest clinical data regarding IgAV therapy. Methods: A narrative literature review, primarily based on articles published in PubMed, was conducted. In addition to discussing the main aspects of glucocorticoids and conventional disease-modifying drugs used in the management of IgAV, this review focuses on the latest information reported regarding biologics and potential future therapies. Results: Glucocorticoids are the first-line therapy for IgAV, especially in adults with severe manifestations. Colchicine, dapsone, and methotrexate can be useful for controlling minor manifestations. Several immunomodulatory agents, such as cyclosporine A, tacrolimus, and mycophenolate mofetil, have shown favorable results as glucocorticoid-sparing agents. Leflunomide has shown promising results but requires further study. The use of rituximab has demonstrated efficacy in reducing relapse frequency, lowering the cumulative glucocorticoid burden, and achieving long-term remission of the disease in children and adults with IgAV. Immunoglobulins and plasma exchange therapy can also be useful in difficult and life-threatening situations. Other potential therapies with encouraging results include TRF-budesonide, B-cell-directed therapy, B-cell-depleting agents, sodium-glucose cotransporter-2 inhibitors, endothelin receptor antagonists, and complement pathway inhibitors. Conclusions: Glucocorticoids are the first-line therapy for IgAV, especially in adults with severe manifestations. The role of various immunomodulatory therapies, such as calcineurin inhibitors and mycophenolate mofetil, remains promising, while rituximab reduces the long-term side effects of glucocorticoids and can help achieve disease remission. Other potential therapies with encouraging results require further research.

Immunoglobulin A Antibodies: From Protection to Harmful Roles

Immunoglobulin A (IgA) is the most abundantly produced antibody in humans. IgA is a unique class of immunoglobulin due to its multiple molecular forms, and a defining difference between the two subclasses: IgA1 has a long hinge-region that is heavily O-glycosylated, whereas the IgA2 hinge-region is shorter but resistant to bacterial proteases prevalent at mucosal sites. IgA is essential for immune homeostasis and education. Mucosal IgA plays a crucial role in maintaining the integrity of the mucosal barrier by immune exclusion of pathobionts while facilitating colonization with certain commensals; a large part of the gut microbiota is coated with IgA. In the circulation, monomeric IgA that has not been engaged by antigen plays a discrete role in dampening inflammatory responses. Protective and harmful roles of IgA have been studied over several decades, but a new understanding of the complex role of this immunoglobulin in health and disease has been provided by recent studies. Here, we discuss the physiological and pathological roles of IgA with a special focus on the gut, kidneys, and autoimmunity. We also discuss new IgA-based therapeutic approaches.

Emerging perspectives in the management of IgA nephropathy: a comprehensive review

IgA nephropathy (IgAN) is the most prevalent form of primary glomerulonephritis worldwide and a leading cause of chronic kidney disease and renal failure. This disorder is characterized by the deposition of immune complexes containing galactose-deficient forms of IgA and complement C3 in the glomeruli. Until now, disease management relied mainly on optimized supportive care. Systemic corticosteroid therapy is proposed for patients at high risk of disease progression, but the effectiveness and safety of this approach are under debate. A significant proportion of patients do not respond to current therapies and require kidney replacement therapy at a young age, with substantial costs and impact on quality of life. Recently, there have been multiple joint efforts to improve the understanding of IgAN pathophysiology. International collaborations resulted in multiple ongoing clinical trials that are providing new insights toward innovative therapeutic options such as SGLT2 inhibitors, dual endothelin and angiotensin receptor blockers, targeted-release budesonide, B-cell proliferation and differentiation inhibitors, and complement system blockers. Based on this new evidence, revision of the guidelines to manage IgAN is expected to occur in the near future. In addition to the novelty in therapeutic agents, there is also a growing interest in new noninvasive biomarkers for IgAN screening, risk stratification to monitor the course of the disease, and the response to treatment. In this review, we discuss current knowledge on the pathophysiology of IgAN, disease management, and emerging advances in clinical translation of IgAN research.

Targeting APRIL in the treatment of glomerular diseases

A proliferation-inducing ligand (APRIL) is a key member of the tumor necrosis factor superfamily of cytokines and plays a central role in B-cell survival, proliferation, and Ig class switching. Recently, there has been increasing interest in the role of APRIL and the related cytokine B-cell activating factor in several glomerular diseases, because of their importance in the above processes. The therapeutic inhibition of APRIL represents a potentially attractive immunomodulatory approach that may abrogate deleterious host immune responses in autoimmune diseases while leaving other important functions of humoral immunity intact, such as memory B-cell function and responses to vaccination, in contrast to B-cell-depleting strategies. In this review, we describe the physiological roles of APRIL in B-cell development and their relevance to glomerular diseases, and outline emerging clinical trial data studying APRIL inhibition, with a focus on IgA nephropathy where the clinical development of APRIL inhibitors is in its most advanced stage.

Drug repurposing for glomerular diseases: an underutilized resource

Drug repurposing in glomerular disease can deliver opportunities for steroid-free regimens, enable personalized multi-target options for resistant or relapsing disease and enhance treatment options for understudied populations (for example, children) and in resource-limited settings. Identification of drug-repurposing candidates can be data driven, which utilizes existing data on disease pathobiology, drug features and clinical outcomes, or experimental, which involves high-throughput drug screens. Information from databases of approved drugs, clinical trials and PubMed registries suggests that at least 96 drugs on the market cover 49 targets with immunosuppressive potential that could be candidates for drug repurposing in glomerular disease. Furthermore, evidence to support drug repurposing is available for 191 immune drug target-glomerular disease pairs. Non-immunological drug repurposing includes strategies to reduce haemodynamic overload, podocyte injury and kidney fibrosis. Recommended strategies to expand drug-repurposing capacity in glomerular disease include enriching drug databases with glomeruli-specific information, enhancing the accessibility of primary clinical trial data, biomarker discovery to improve participant selection into clinical trials and improve surrogate outcomes and initiatives to reduce patent, regulatory and organizational hurdles.

New Insights and Future Perspectives of APRIL in IgA Nephropathy

IgA nephropathy (IgAN) is characterized by immune-mediated glomerulonephritis, with the accumulation of galactose-deficient IgA1 (Gd-IgA1) in the glomeruli and increased levels of circulating Gd-IgA1 and Gd-IgA1-containing immune complexes. An incomplete understanding of the underlying mechanisms and differences in clinical and pathological features between individuals and ethnicities has contributed to the lack of established treatments for IgAN. A tumor necrosis factor (TNF) family member, a proliferation-inducing ligand (APRIL), is a crucial cytokine essential for the generation and survival of plasma cells. Recent studies demonstrated that APRIL is a pivotal mediator in the production of Gd-IgA1 in IgAN. As our understanding of the autoimmune pathogenesis underlying IgAN has improved, various pharmacological therapeutic targets, including APRIL antagonists, have emerged. Preliminary results showed that APRIL-targeting agents effectively reduced proteinuria and Gd-IgA1 levels without significantly increasing adverse events, indicating their potential as novel therapeutic agents for IgAN. In the present review, we discuss the current understanding of the role of APRIL in the pathogenesis of IgAN and novel therapeutic strategies focusing on APRIL-targeting agents for IgAN. APRIL inhibitors may offer new hope to patients with IgAN.

The efficacy of rituximab in the treatment of IgA vasculitis nephritis

The utility of Rituximab (RTX) for IgA vasculitis nephritis (IgAVN) is not well established. Up to now, we analysed the largest samples of IgAVN patients treated by RTX with a total of 41 retrieved subjects up to December 29, 2023 in the present systematic review. We assessed the clinical profiles, efficacy, and safety of RTX treatments. The present review showed that the renal function tended to be stabilized (P = 1.000) and urinalysis tended to normalize after RTX treatment with no serious adverse events reported. Moreover, 40% (16/40) of patients was freed use of glucocorticoid after RTX administration (P < 0.001). The remission rate was 92.7% (38/41) and complete remission rate was 46.3% (19/41) in IgAVN patients. Interestingly, 76.9% (10/13) of IgAVN child patients achieved complete remission when compared with 32.1% (9/28) of adult patients (P = 0.017). In summary, our results support the benefit of RTX therapy in IgAVN patients, especially children subjects.

B cell targeting in IgA nephropathy

The "multi-hit theory/4-hit theory" pathogenesis hypothesis is widely accepted and IgA nephropathy (IgAN) is understood to be a disease originating from Hit 1, galactose deficient IgA1 (GdIgA1). The chronic repetitive activation of the complement pathway (alternative and lectin pathways) and the subsequent inflammation results in progressive glomerular damage that spills over into increased intraglomerular pressure and other hemodynamic changes, increased urinary protein, glomerulosclerosis, and tubulointerstitial fibrosis. The basic pathophysiology of this disease is the progression of a mixture of such acute and chronic pathologies. Currently, a number of new drugs has emerged as promising agents, such as complement regulators, endothelin receptor antagonists, and SGLT2 inhibitors, which are associated with each pathological step after glomerular deposition of GdIgA1/immune complexes. On the other hand, the molecular mechanisms of GdIgA1 production are gradually being elucidated, and the development of several novel therapeutic agents targeting the responsible B cells and their international clinical trials are progressing. These agents that inhibit or control the production of the Hit1, GdIgA1, are highly expected as essential therapies for this disease. The large body of clinical and basic research findings to date strongly suggest that nephritogenic GdIgA1 is a polymeric IgA1 of mucosal origin. In addition, the B cells involved in its nephritogenic GdIgA1 production are mainly differentiated mature B cells such as plasma cells, which may migrate to the bone marrow as well as the mucosa. The innate immune system in the mucosa, especially Toll-like receptors (TLRs), is thought to be involved in their production. Among TLRs, TLT9 and TLR7, which recognize bacterial and viral unmethylated DNA and RNA, have been reported to be involved. The mucosal activation of these TLRs is associated with the production of APRIL (A Proliferation Inducing Ligand) and BAFF (B cell activating factor), which are TNF superfamily cytokines involved in B cell maturation, survival, and IgA class switching, and may also be involved in the production of nephritogenic GdIgA1. It is still inconclusive whether APRIL or BAFF is more closely involved in the production of nephritogenic GdIgA1. Phenotypes in transgenic animal models suggest BAFF involvement, however, a genome wide association study (GWAS) analysis of human IgAN has identified APRIL, not BAFF, as a candidate gene. Based on the above background, several international clinical trials are underway for drugs such as TLR regulators (hydroxychloroquine), anti-APRIL drugs, anti-BAFF drugs, APRIL/BAFF receptor (TACI) binding inhibitors, and cytoreductive drugs (proteasome inhibitors, anti-CD38 antibodies) to inhibit nephritogenic GdIgA1 production in responsible B cells. This session will provide an overview of the responsible B cells, their GdIgA1 production mechanism, and ongoing drugs.

Telitacicept: A novel horizon in targeting autoimmunity and rheumatic diseases

BLyS and APRIL have the capability to bind to B cells within the body, allowing these cells to evade elimination when they should naturally be removed. While BLyS primarily plays a role in B cell development and maturation, APRIL is linked to B cell activation and the secretion of antibodies. Thus, in theory, inhibiting BLyS or APRIL could diminish the population of aberrant B cells that contribute to SLE and reduce disease activity in patients. Telitacicept functions by binding to and neutralizing the activities of both BLyS and APRIL, thus hindering the maturation and survival of plasma cells and fully developed B cells. The design of telitacicept is distinctive; it is not a monoclonal antibody but a TACI-Fc fusion protein generated through recombinant DNA technology. This fusion involves merging gene segments of the TACI protein, which can target BLyS/APRIL simultaneously, with the Fc gene segment of the human IgG protein. The TACI-Fc fusion protein exhibits the combined characteristics of both proteins. Currently utilized for autoimmune disease treatment, telitacicept is undergoing clinical investigations globally to assess its efficacy in managing various autoimmune conditions. This review consolidates information on the mechanistic actions, dosing regimens, pharmacokinetics, efficacy, and safety profile of telitacicept-a dual-targeted biological agent. It integrates findings from prior experiments and pharmacokinetic analyses in the treatment of RA and SLE, striving to offer a comprehensive overview of telitacicept's research advancements.

Current understanding and new insights in the treatment of IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide, and almost all patients are at risk of progression to end-stage kidney disease within their lifetime. The mechanisms responsible for the presentation and development of IgAN are required for the development of highly targeted therapies for this disease. In this review, we first demonstrate the current treatment strategy of IgAN recommended by the 2021 KDIGO guideline. Then, we update the new insights into disease pathogenesis based on the well acknowledged 'multiple-hit hypothesis' and provide the potential therapeutic targets involved in the upstream production of pathogenic IgA1 and the downstream complement activation. Finally, the recent large randomized controlled trials focusing on these novel targets have been summarized, among which Nefecon and Sparsentan have received approval and Telitacicept have been used off-label for IgAN. In the future, emerging treatment approaches for IgAN is likely to evolve, which will signify a shift in the management of the IgAN from traditional immunosuppressive approaches to an era of targeted treatment based on the understanding of the pathogenic mechanisms.

The Rapidly Changing Treatment Landscape of IgA Nephropathy

The past few years have heralded a sea change in the treatment landscape of IgA nephropathy (IgAN). An increasing understanding of its pathogenesis coupled with favorable changes in the regulatory approval pathway has led to an explosion of clinical drug development in this disease. This has directly resulted in the approval of three novel therapies specifically for the treatment of IgAN (nefecon, sparsentan, and iptacopan), and several others are in the late stages of clinical development. In this review, we outline the rationale for new therapies in development for IgAN and emerging clinical trial data and propose a new paradigm for the treatment of this condition.

The Role of Mucosal Immunity: What Can We Learn From Animal and Human Studies?

Immunoglobulin A (IgA) is a key actor in the mucosal immune system, which moderates interactions between the host and environmental factors such as food antigens and commensal microorganisms. The pathogenesis of IgA nephropathy (IgAN) involves a multistep process starting with deglycosylation of mucosally derived, polymeric IgA1 (dg-IgA1) that reaches the circulation. Modified O-glycans on dg-IgA1 are targeted by IgG-autoantibodies, leading to the formation of circulating immune complexes that deposit in the glomerular mesangium. Infections of mucosal surfaces trigger flares of primary IgAN, while inflammatory bowel disease and liver cirrhosis are important causes of secondary IgAN, supporting a mucosal source of nephritogenic IgA1. In the presence of microbial pathogens or food antigens, activated dendritic cells in the gut mucosa induce T-cell-dependent or T-cell-independent B-cell differentiation into IgA-secreting plasma cells. Herein we review the literature concerning mucosal immune function and how it is altered in this disease. We discuss recent evidence supporting a causal role of gut microbiota dysbiosis in IgAN pathogenesis.

Post-transplant IgA Nephropathy

Immunoglobulin A (IgA) nephropathy is the most common glomerulonephritis in many countries. Most patients progress to kidney failure for which kidney transplantation is the optimal therapy. Unfortunately, IgA nephropathy commonly recurs post transplant and shortens allograft survival. Multiple recipient and donor characteristics have been associated with the risk of recurrence, although these have varied between different cohorts. The clinical expression of post-transplant IgA nephropathy is modified by immunosuppression. Biomarkers have been identified and studied in native-kidney IgA nephropathy but need validation in transplantation. Treatment of recurrent IgA nephropathy hinges on supportive measures derived largely from evidence in native-kidney IgA nephropathy. The improved understanding of the autoimmune mechanisms of disease in native-kidney IgA nephropathy has led to promising new targets for treatment, which may in turn be deployed in post-transplant IgA nephropathy.

IgA Vasculitis and IgA Nephropathy: Two Sides of the Same Coin?

IgA vasculitis (IgAV) is considered a systemic form of IgA nephropathy (IgAN). The two diseases share similar geographic and ethnic distribution, along with common variants in genetic association studies. The pathophysiology of IgAN and IgA vasculitis nephritis (IgAVN) can be explained by the four-hit hypothesis. Key molecules involved at each step in both diseases were evaluated as diagnostic and prognostic biomarkers with many common factors, most prominently serum galactose-deficient IgA1. On kidney biopsy, the two diseases are indistinguishable, and the established histological Oxford classification for IgAN will soon be validated for IgAVN. Chronic lesions (segmental glomerulosclerosis and tubular atrophy / interstitial fibrosis) seem more frequent in IgAN, while proliferative lesions (endocapillary hypercellularity and crescents) are more frequent in IgAVN, which could explain the worse IgAN renal prognosis. Due to characteristic skin rash, IgAVN patients are diagnosed precociously. Conversely, the frequent absence of overt clinical signs in IgAN leads to a delayed diagnostic kidney biopsy in the disease evolution, which explains the chronic pathologic lesions. From a therapeutic perspective, while impressive advances have been made in recent years for IgAN, there is a glaring lack of evidence-based guidelines for the treatment of IgAVN. Large therapeutic clinical studies are required, and future IgAN trials should include IgAVN.

Therapy of IgA nephropathy: time for a paradigm change

Immunoglobulin A nephropathy (IgAN) often has a poor outcome, with many patients reaching kidney failure within their lifetime. Therefore, the primary goal for the treatment of IgAN should be to reduce nephron loss from the moment of diagnosis. To achieve this, IgAN must be recognized and treated as both a chronic kidney disease and an immunological disease. Agents that have received US Food and Drug Administration and European Medicines Agency approval for the treatment of IgAN include modified-release/targeted-release formulation budesonide (Nefecon) and sparsentan, a selective dual endothelin-A and angiotensin II receptor type 1 antagonist. Other agents, including selective endothelin receptor antagonists, selective or combined APRIL and BAFF antagonists, and a vast array of complement inhibitors are being investigated for the treatment of IgAN. Furthermore, treatment combinations are also being studied, including sodium-glucose cotransporter-2 inhibitors with endothelin receptor antagonists. Due to the complexity of IgAN, combination treatment, rather than a single-agent approach, may provide maximum benefit. With the number of treatments for IgAN likely to increase, combinations allowing safe and effective treatment to halt progression to kidney failure seem within grasp. While trials evaluating combinations are ongoing, more are needed to pave the way for a comprehensive IgAN treatment strategy. Furthermore, an approach to IgAN treatment in which agents are combined early to achieve rapid induction of remission and prevent unnecessary and irreversible nephron loss is required. Following remission, treatments may be adjusted and stripped back as necessary in the maintenance phase with close monitoring. This review discusses the current status of IgAN treatment and explores future strategies to improve outcomes for patients with IgAN.

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.

A multicenter, randomized, open-label, phase 2 clinical study of telitacicept in adult patients with generalized myasthenia gravis

BACKGROUND AND PURPOSE

This study aimed to investigate the clinical efficacy and safety of telitacicept in patients with generalized myasthenia gravis (gMG) who tested positive for acetylcholine receptor antibodies or muscle-specific kinase antibodies and were receiving standard-of-care therapy.

METHODS

Patients meeting the eligibility criteria were randomly assigned to receive telitacicept subcutaneously once a week for 24 weeks in addition to standard-of-care treatment. The primary efficacy endpoint was the mean change in the quantitative myasthenia gravis (QMG) score from baseline to week 24. Secondary efficacy endpoints included mean change in QMG score from baseline to week 12 and gMG clinical absolute score from baseline to week 24. Additionally, safety, tolerability and pharmacodynamics were assessed.

RESULTS

Twenty-nine of the 41 patients screened were randomly selected and enrolled. The mean (± standard deviation [SD]) reduction in QMG score from baseline to week 24 was 7.7 (± 5.34) and 9.6 (± 4.29) in the 160 mg and 240 mg groups, respectively. At week 12, mean reductions in QMG scores for these two groups were 5.8 (± 5.85) and 9.5 (± 5.03), respectively, indicating rapid clinical improvement. Safety analysis revealed no adverse events leading to discontinuation or mortalities. All patients showed consistent reductions in serum immunoglobulin (Ig) A, IgG and IgM levels throughout the study.

CONCLUSION

Telitacicept demonstrated safety, good tolerability and reduced clinical severity throughout the study period. Further validation of the clinical efficacy of telitacicept in gMG will be conducted in an upcoming phase 3 clinical trial.

Navigating Adult-Onset IgA Vasculitis-Associated Nephritis

PURPOSE OF REVIEW

IgA vasculitis (IgAV), formerly Henoch-Schonlein purpura, is the most common systemic vasculitis in childhood. In adults, however, this condition is poorly understood, yet associated with more severe disease and poorer outcomes. This necessitates the need for early diagnosis and management.

SCOPE OF REVIEW

We describe the pathophysiology, clinical manifestations, and diagnosis of IgAV in adults. Poor outcomes are often due to the high frequency of glomerulonephritis in IgAV-IgA vasculitis-associated nephritis (IgAVN). We hence also aim to summarize the latest clinical data regarding treatment strategies in IgAVN. The diagnosis and differentiation in histology between IgAVN and IgA nephropathy (IgAN) remain a challenge. Review of treatment therapies: Pathological mechanisms between IgAVN and IgAN appear to be consistent between the two, and data from IgAN are often extrapolated to IgAVN. The role of various immunosuppression therapies remains controversial, and in this review, we will discuss immunosuppression use and highlight evidence surrounding emerging and promising novel therapies in IgAVN/IgAN. Our aim for this review is to guide future treatment strategies and direct future studies.

IgA Nephropathy: Emerging Mechanisms of Disease

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis reported across the world and is characterized by immunoglobulin A (IgA) dominant mesangial deposits, which are poorly O-glycosylated. This deposition leads to a cascade of glomerular and tubulointerstitial inflammation and fibrosis, which can progress to chronic kidney disease. The variability in rate of progression reflects the many genetic and environmental factors that drive IgAN. Here, we summarize the contemporary understanding of the disease mechanisms that drive IgAN and provide an overview of new and emerging therapies, which target these mechanisms.

Successful pregnancy in a patient with IgA nephropathy treated with telitacicept: a case report

BACKGROUND

IgA nephropathy (IgAN) is the most common cause of primary glomerulonephritis, with complex pathogenic mechanisms involving abnormal B-cell activation. As a novel biologic agent, telitacicept inhibits both B-lymphocyte stimulating factor and a proliferation-inducing ligand. It also inhibits both B cells and plasma cells and the production of galactose-deficient IgA1 (Gd-IgA1) and its autoantibodies, thus exerting an immunosuppressive effect. Women with IgAN are at a higher risk of adverse pregnancy outcomes such as preeclampsia and miscarriage, especially those with uncontrolled massive proteinuria and advanced chronic kidney disease. Therefore, IgAN disease control before and during pregnancy is essential. Here, we report the case of a woman with IgAN who had a successful pregnancy with significant improvement and long-term remission after treatment with telitacicept. This is the first report of a pregnancy following exposure to telitacicept.

CASE REPORT

CONCLUSION

This report describes the efficacy of telitacicept in patients with IgAN and explores its value in women of childbearing age, suggesting effective and safe treatment options for women who wish to conceive.

Immunosuppressive therapy for IgA nephropathy in children

BACKGROUND

IgA nephropathy (IgAN) is the most common cause of primary glomerulonephritis. It is a heterogeneous disease with different presentations and high morbidity. Thirty per cent of adults and 20% of children (followed into adulthood) will have a 50% decline in kidney function or develop kidney failure after 10 years.

OBJECTIVES

To determine the benefits and harms of immunosuppressive therapy for the treatment of IgAN in children.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 03 October 2023 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) investigating the treatment of IgAN in children with immunosuppressive therapies compared to placebo, no treatment, supportive care, standard therapy (Japanese protocol), other immunosuppressive therapies or non-immunosuppressive therapies.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed the risk of bias. Random effects meta-analyses were used to summarise estimates of treatment effects. Treatment effects were expressed as risk ratios (RR) and 95% confidence intervals (CI) for dichotomous outcomes, and the mean difference (MD) and 95% CI for continuous outcomes. The risk of bias was assessed using the Cochrane risk of bias tool for RCTs and the ROBIN-I tool for NRSIs. The certainty of the evidence was assessed using Grading of Recommendations, Assessment, Development, and Evaluations (GRADE).

MAIN RESULTS

This review included 13 studies with 686 participants. Ten RCTs included 334 children and 191 adults, and three NRSIs included 151 participants, all children. Most participants had mild kidney disease. The risk of bias was unclear for most of the domains relating to allocation concealment, blinding of participants, personnel, and outcome assessment. In children with IgAN, it is uncertain if corticosteroid (steroid) therapy, compared to placebo reduces proteinuria (1 study, 64 children and young adults: RR 0.47, 95% CI 0.13 to 1.72; low certainty evidence) or the decline in estimated glomerular filtration rate (eGFR) (1 study, 64 children and young adults: RR 0.47, 95% CI 0.09 to 2.39; low certainty evidence). It is uncertain if steroids reduce proteinuria compared to supportive care (2 studies, 61 children: RR 0.04, 95% CI -0.83 to 0.72; low certainty evidence). Adverse events associated with steroid therapy were not assessed due to heterogeneity in steroid protocols, including dose and duration, and lack of systematic assessment for adverse events in the included studies. Azathioprine, mycophenolate mofetil, mizoribine, or cyclophosphamide alone or in combination with steroid therapy had uncertain effects on improving proteinuria or preventing eGFR decline in children with IgAN. Fish oil, vitamin E and tonsillectomy had uncertain effects on improving proteinuria or preventing eGFR decline. Effects of other immunosuppressive therapies, secondary outcomes and adverse events were not assessed due to insufficient data.

AUTHORS' CONCLUSIONS

There is a lack of high-quality evidence to guide the management of IgAN in children. There is no evidence to indicate that steroids, other immunosuppressive therapies, or tonsillectomy, when added to optimal supportive care, prevent a decline in eGFR or proteinuria in children with IgAN. Available studies were few, with small numbers, low-quality evidence, high or uncertain risk of bias, did not systematically assess harms associated with treatment, or report net benefits or harms. Severe cases and atypical presentations of IgAN were not included in the reviewed studies, and our findings cannot be generalised to these situations.

Primary IgA Nephropathy: New Insights and Emerging Therapies

Primary IgA nephropathy (IgAN) is a common glomerular disorder defined by predominant mesangial IgA deposition. Once thought to follow a progressive course in 10-20% of those diagnosed, emerging evidence now suggests most will progress to kidney failure over their lifetimes. Although the lack of safe and effective treatments to impede disease progression continues to present a challenge, the landscape of IgAN has dramatically evolved over the last 2 years. Driven by fundamental changes to accepted end points for IgAN clinical trials as well as fascinating new insights into the pathophysiology of IgAN, a swathe of novel and repurposed therapies are currently being evaluated. Already, two novel drugs, targeted-release formulation budesonide and sparsentan, have received conditional approvals for the treatment of IgAN, with sodium glucose co-transporter 2 inhibitors establishing themselves as further options. Soon to join this ensemble are likely to be treatments that modulate the complement system and B-cell activity; several are currently undergoing clinical trials in IgAN with promising interim results. In this review, we provide an overview of evolving epidemiological insights, disease mechanisms, emerging therapies, and contemporary challenges surrounding the management of IgAN.

Drugs in Development to Treat IgA Nephropathy

IgA nephropathy is a common glomerulonephritis consequent to the autoimmune response to aberrant glycosylated immunoglobulin (Ig) A antibodies. Although it has historically been considered a benign disease, it has since become clear that a substantial percentage of patients reach end-stage kidney failure over the years. Several therapeutic attempts have been proposed, with systemic steroids being the most prevalent, albeit burdened by possible serious adverse events. Thanks to the more in-depth knowledge of the pathogenesis of IgA nephropathy, new treatment targets have been identified and new drugs developed. In this narrative review, we summarise the molecules under clinical development for the treatment of IgA nephropathy. As a search strategy, we used PubMed, Google, ClinicalTrials.gov and abstracts from recent international congresses. TRF budesonide and sparsentan are the two molecules at a more advanced stage, just entering the market. Other promising agents are undergoing phase III clinical development. These include anti-APRIL and anti-BLyS/BAFF antibodies and some complement inhibitors. Other new possible strategies include spleen tyrosine kinase inhibitors, anti-CD40 ligands and anti-CD38 antibodies. In an era increasingly characterised by 'personalised medicine' and 'precision therapy' approaches and considering that the potential therapeutic armamentarium for IgA nephropathy will be very broad in the near future, the identification of biomarkers capable of helping the nephrologist to select the right drug for the right patient should be the focus of future studies.

Biologics and Non-Biologics Immunosuppressive Treatments for IgA Nephropathy in Both Adults and Children

Immunoglobulin A nephropathy represents the most prevalent cause of glomerulonephritis worldwide and may lead to renal failure in a relevant number of cases in both paediatric and adult subjects. Although their pathogenesis is still largely unclear, evidence of immune abnormalities provides the background for the use of immunosuppressive drugs, such as corticosteroids, calcineurin inhibitors, and antiproliferative and alkylating agents. Unfortunately, these treatments fail to achieve a sustained remission in a significant percentage of affected patients and are burdened by significant toxicities. Recent developments of new biologics, including anti-BAFF/APRIL inhibitors and molecules targeting complement components, offered the opportunity to selectively target immune cell subsets or activation pathways, leading to more effective and safer hypothesis-driven treatments. However, studies testing new biologic agents in IgAN should also consider paediatric populations to address the unique needs of children and close the therapeutic gap between adult and paediatric care.

Efficacy and safety of biologic agents for IgA nephropathy: A protocol for systematic review and meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis worldwide and a leading cause of chronic kidney failure. There are currently no definitive therapeutic regimens to treat or prevent the progression of IgAN. However, biologic agents offer novel therapeutic approaches that target immunological mechanisms to slow or halt disease progression. The objective of this study is to evaluate the efficacy and safety of biologic agents in patients with IgA nephropathy.

METHODS

We will systematically search PubMed, EMbase, Web of Science, Cochrane Library, and www.clinicaltrials.gov for randomized controlled trials of biologic agents for the treatment of IgA nephropathy. The search period will span from the establishment of each database until October 2023. The quality assessment of included studies will be performed individually using the revised Cochrane risk-of-bias tool for randomized trials (RoB 2), and meta-analysis will be conducted using Revman 5.4.1 software.

CONCLUSIONS

The results of this study will provide evidence-based medical evidence for the clinical application of biologic agents in patients with IgA nephropathy.

PROSPERO REGISTRATION NUMBER

CRD42023400450.

Advances in the treatment of IgA nephropathy with biological agents

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease, and the "four-hit" theory represents its currently accepted pathogenic mechanism. Mucosal immunity triggered by infections in the respiratory tract, intestines, or other areas leads to antigen presentation, T cell stimulation, B cell maturation, and the production of IgA-producing plasma cells. The proteins B-lymphocyte stimulator (BLyS) and a proliferation-inducing ligand (APRIL) are involved in this process, and alternative complement and lectin pathway activation are also part of the pathogenic mechanism. Kidney Disease Improving Global Outcomes guidelines indicate that a specific effective treatment for IgAN is lacking, with renin-angiotensin-aldosterone system inhibitors being the primary therapy. Recent research shows that biological agents can significantly reduce proteinuria, stabilize the estimated glomerular filtration rate, and reverse some pathological changes, such as endocapillary proliferation and crescent formation. There are four main categories of biological agents used to treat IgA nephropathy, specifically anti-CD20 monoclonal antibodies, anti-BLyS or APRIL monoclonal antibodies, monoclonal antibodies targeting both BLyS and APRIL (telitacicept and atacicept), and monoclonal antibodies inhibiting complement system activation (narsoplimab and eculizumab). However, further research on the dosages, treatment duration, long-term efficacy, and safety of these biological agents is required.

An Update on Current Therapeutic Options in IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) remains the leading cause of primary glomerular disease worldwide. Outcomes are poor with high rates of progressive chronic kidney disease and kidney failure, which contributes to global healthcare costs. Although this disease entity has been described, there were no disease-specific treatments until recently, with the current standard of care focusing on optimal supportive measures including lifestyle modifications and optimization of the renin-angiotensin-aldosterone blockade. However, with significant advances in the understanding of the pathogenesis of IgAN in the past decade, and the acceptance of surrogate outcomes for accelerated drug approval, there have been many new investigational agents tested to target this disease. As these agents become available, we envision a multi-pronged treatment strategy that simultaneously targets the consequences of ongoing nephron loss, stopping any glomerular inflammation, inhibiting pro-fibrotic signals in the glomerulus and tubulo-interstitium, and inhibiting the production of pathogenic IgA molecules. This review is an update on a previous review published in 2021, and we aim to summarize the developments and updates in therapeutic strategies in IgAN and highlight the promising discoveries that are likely to add to our armamentarium.

Novel Treatment Paradigms: Primary IgA Nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Approximately 30% to 45% of patients progress to kidney failure (KF) within 20 to 25 years of diagnosis, and there has long been a lack of effective treatments. The therapeutic landscape in IgAN is rapidly evolving, driven in large part by the acceptance of the surrogate clinical trial end point of proteinuria reduction by regulatory authorities for the accelerated approval of new therapies. Two drugs, targeted release formulation (TRF)-budesonide (nefecon) and sparsentan, have recently been approved under this scheme. Advancing insights into the pathophysiology of IgAN, including the roles of the mucosal immune system, B-cells, the complement system, and the endothelin system have driven development of therapies that target these factors. This review outlines current, recently approved, and emerging therapies for IgAN.

The Treatment of Primary IgA Nephropathy: Change, Change, Change

IgA nephropathy (IgAN) is the most common glomerular disease in the world. However, the approach to treatment remains controversial. There has been an explosion of clinical trials over the past decade both to further examine corticosteroid use and usher in additional treatment considerations, including 2 newly approved therapies for IgAN. Sodium glucose cotransporter 2 inhibitors are proving to be effective therapy across proteinuric chronic kidney diseases, and IgAN is not likely to be an exception. Further supportive agents are looking highly promising and so are novel agents that specifically focus on the pathophysiology of this disease, including endothelin blockade, complement inhibition, and B-cell targeted strategies. We suggest a present-day approach to treatment of individuals with IgAN, expose the limitations in our knowledge, and discuss new treatments that may arise, hoping they come with evidence about optimal utilization. Change appears to be inevitable for our approach to the treatment of IgA nephropathy. This is truly an exciting and optimistic time.

The role of BAFF and APRIL in IgA nephropathy: pathogenic mechanisms and targeted therapies

Immunoglobulin A nephropathy (IgAN), characterized by mesangial deposition of galactose-deficient-IgA1 (Gd-IgA1), is the most common biopsy-proven primary glomerulonephritis worldwide. Recently, an improved understanding of its underlying pathogenesis and the substantial risk of progression to kidney failure has emerged. The "four-hit hypothesis" of IgAN pathogenesis outlines a process that begins with elevated circulating levels of Gd-IgA1 that trigger autoantibody production. This results in the formation and deposition of immune complexes in the mesangium, leading to inflammation and kidney injury. Key mediators of the production of Gd-IgA1 and its corresponding autoantibodies are B-cell activating factor (BAFF), and A proliferation-inducing ligand (APRIL), each playing essential roles in the survival and maintenance of B cells and humoral immunity. Elevated serum levels of both BAFF and APRIL are observed in patients with IgAN and correlate with disease severity. This review explores the complex pathogenesis of IgAN, highlighting the pivotal roles of BAFF and APRIL in the interplay between mucosal hyper-responsiveness, B-cell activation, and the consequent overproduction of Gd-IgA1 and its autoantibodies that are key features in this disease. Finally, the potential therapeutic benefits of inhibiting BAFF and APRIL in IgAN, and a summary of recent clinical trial data, will be discussed.

Expression and Clinical Significance of Non B Cell-Derived Immunoglobulins in the Urinary System and Male Reproductive System

The urinary system comprises kidneys, ureters, bladder, and urethra with its primary function being excretion, referring to the physiological process of transporting substances that are harmful or surplus out of the body. The male reproductive system consists of gonads (testis), vas deferens, and accessory glands such as the prostate. According to classical immunology theory, the tissues and organs mentioned above are not thought to produce immunoglobulins (Igs), and any Ig present in the relevant tissues under physiological and pathological conditions is believed to be derived from B cells. For instance, most renal diseases are associated with uncontrolled inflammation caused by pathogenic Ig deposited in the kidney. Generally, these pathological Igs are presumed to be produced by B cells. Recent studies have demonstrated that renal parenchymal cells can produce and secrete Igs, including IgA and IgG. Glomerular mesangial cells can express and secrete IgA, which is associated with cell survival and adhesion. Likewise, human podocytes demonstrate the ability to produce and secrete IgG, which is related to cell survival and adhesion. Furthermore, renal tubular epithelial cells also express IgG, potentially involved in the epithelial-mesenchymal transition (EMT). More significantly, renal cell carcinoma, bladder cancer, and prostate cancer have been revealed to express high levels of IgG, which promotes tumour progression. Given the widespread Ig expression in the urinary and male reproductive systems, continued efforts to elucidate the roles of Igs in renal physiological and pathological processes are necessary.

Treatment of IgA Nephropathy: A Rapidly Evolving Field

The pivotal event in the pathophysiology of IgA nephropathy is the binding of circulating IgA-containing immune complexes to mesangial cells, with secondary glomerular and tubulointerstitial inflammation and fibrosis. The paramount difficulty in the management of IgA nephropathy is the heterogeneity in its clinical presentation and prognosis, requiring an individualized treatment approach. Goal-directed supportive care remains the bedrock of therapy for all patients, regardless of risk of progression. Sodium-glucose transporter 2 inhibitors and sparsentan should be integral to contemporary supportive care, particularly in patients with chronic kidney damage. Pending the development of reliable biomarkers, it remains a challenge to identify patients prone to progression due to active disease and most likely to derive a net benefit from immunosuppression. The use of clinical parameters, including the degree of proteinuria, the presence of persistent microscopic hematuria, and the rate of eGFR loss, combined with the mesangial hypercellularity, endocapillary hypercellularity, segmental glomerulosclerosis, tubular atrophy/interstitial fibrosis, crescents score, is currently the best approach. Systemic glucocorticoids are indicated in high-risk patients, but the beneficial effects wane after withdrawal and come at the price of substantial treatment-associated toxicity. Therapies with direct effect on disease pathogenesis are increasingly becoming available. While targeted-release budesonide has garnered the most attention, anti-B-cell strategies and selective complement inhibition will most likely prove their added value. We propose a comprehensive approach that tackles the different targets in the pathophysiology of IgA nephropathy according to their relevance in the individual patient.