Rationale and design of the Nephrotic Syndrome Study Network (NEPTUNE) Match in glomerular diseases: designing the right trial for the right patient, today

Emerging pharmacotherapies for the treatment of childhood nephrotic syndrome

INTRODUCTION

Childhood nephrotic syndrome (NS) is a relatively rare condition but an important cause of morbidity. It is classified based on histopathology and response to corticosteroid therapy.

AREAS COVERED

Children with steroid-sensitive disease have a favorable long-term prognosis with maintenance of normal kidney function. However, nearly half of these patients have persistent disease activity requiring chronic corticosteroid therapy or exposure to second-line immunosuppressive agents. The identification of anti-nephrin antibodies in many patients with steroid-sensitive disease suggests immunotherapy to reduce pathogenic antibody formation may represent a qualitative advance in treatment. Children with steroid-resistant disease are likely to have focal segmental glomerulosclerosis (FSGS). There are no approved treatments for this condition. FSGS is a heterogeneous entity, and improvements in care will likely depend on molecular classification of subtypes based on the underlying disease mechanism. This approach will enable selection of treatments that match the cause of NS in each child for precision medicine therapy.

EXPERT OPINION

Children with NS today benefit from therapeutic options not previously available, but clinical decisions still rely on steroid responsiveness at disease onset. Continued advancement in treating NS requires collaboration between basic scientists and nephrologists and the organization of a clinical trial framework to evaluate novel therapies.

Development of a Diagnostic Model for Focal Segmental Glomerulosclerosis: Integrating Machine Learning on Activated Pathways and Clinical Validation

Background

Focal segmental glomerulosclerosis (FSGS) represents a major global health challenge, with its incidence rising in parallel with advances in diagnostic techniques and the growing prevalence of chronic diseases. This study seeks to enhance the diagnostic accuracy of FSGS by integrating machine learning approaches to identify activated pathways, complemented by robust clinical validation.

Methods

We analyzed data from 163 FSGS patients and 42 living donors across multiple GEO cohorts via the ComBat algorithm to address batch effects and ensure the comparability of gene expression profiles. Gene set enrichment analysis (GSEA) identified key signaling pathways involved in FSGS pathogenesis. We then developed a highly accurate diagnostic model by integrating nine machine learning algorithms into 101 combinations, achieving near-perfect AUC values across training, validation, and external cohorts. The model identified six genes as potential biomarkers for FSGS. Additionally, immune cell infiltration patterns, particularly those involving natural killer (NK) cells, were explored, revealing the complex interplay between genetics and the immune response in FSGS patients. Immunohistochemical analysis validated the expression of the key markers CD99 and OAZ2 and confirmed the association between NK cells and FSGS.

Results

The glmBoost+Ridge model exhibited exceptional diagnostic accuracy, achieving an AUC of 0.998 using just six genes: BANF1, TUSC2, SMAD3, TGFB1, CD99, and OAZ2. The prediction score was calculated as follows: score = (0.3997×BANF1) + (0.5543×TUSC2) + (0.5279×SMAD3) + (0.4118×TGFB1) + (0.8665×CD99) + (0.5996×OAZ2). Immunohistochemical analysis confirmed significantly elevated expression levels of CD99 and OAZ2 in the glomeruli and tubulointerstitial tissues of FSGS patients compared with those of controls.

Conclusion

This study demonstrates a highly accurate machine learning model for FSGS diagnosis. Immunohistochemical validation confirmed elevated expression of CD99 and OAZ2, offering valuable insights into FSGS pathogenesis and potential biomarkers for clinical application.

Advances in Focal Segmental Glomerulosclerosis Treatment From the Perspective of the Newest Mechanisms of Podocyte Injury

Podocyte injury was widely recognized as a fundamental mechanism driving the progression of focal segmental glomerulosclerosis (FSGS). Recent research has therefore focused on the development of targeted therapies aimed at disrupting specific pathogenic signaling cascades within podocytes, resulting in noteworthy advancements. The role of mechanisms such as alterations in the actin cytoskeleton, oxidative stress, mitochondrial dysfunction, and inadequate autophagy within the microenvironment of podocyte injury have garnered increasing attention. Corresponding targeted medications such as Abatacept, chemokine receptor (CCR) inhibitors, CDDO-Im (2-Cyano-3,12-dioxooleana-1,9-dien-28-imidazolide), adenosine monophosphate-activated protein kinase (AMPK) activators, and Adalimumab are currently under investigation. Notably, some medications such as Rituximab and Sparsentan, may simultaneously target multiple downstream mechanisms, Furthermore, exploring molecular strategies for established medications and developing novel treatments guided by biomarkers such as Anti-CD40 antibody, blood microRNA, urinary microRNA, and tumor necrosis factor-alpha (TNF-α) may provide additional therapeutic avenues for patients with FSGS.

Precision Medicine Proof-of-Concept Study of a TNF Inhibitor in FSGS and Treatment-Resistant Minimal Change Disease

Key Points

Precision medicine trials are feasible in patients with primary glomerular diseases. Patients with FSGS and the best-preserved kidney parenchyma demonstrated the most favorable biomarker response to short-term adalimumab treatment. Targeted therapies for FSGS are more likely to succeed during the course of disease when the injury pathway is activated and can be modified.

Background

FSGS and treatment-resistant minimal change disease (TR-MCD) are heterogeneous disorders with subgroups defined by distinct underlying mechanisms of glomerular and tubulointerstitial injury. A noninvasive urinary biomarker profile has been generated to identify patients with intrakidney TNF activation and to predict response to anti-TNF treatment. We conducted this proof-of-concept, multicenter, open-label clinical trial to test the hypothesis that in patients with FSGS or TR-MCD and evidence of intrarenal TNF activation based on their biomarker profile, short-term treatment with adalimumab would reverse the elevated urinary excretion of monocyte chemoattractant protein-1 (MCP-1) and tissue inhibitor of metalloproteinases 1.

Methods

Patients with FSGS or TR-MCD, eGFR >30 ml/min per 1.73 m2, urine protein:creatinine ratio ≥1.5 g/g, and age 6–80 years were eligible for this trial. Adalimumab, 20–40 mg, was administered through subcutaneous injection every 2 weeks for five doses. Participants were evaluated at weeks 0 (baseline), 2, 8, and 10. Excretion of urinary monocyte chemoattractant protein-1, urinary tissue inhibitor of metalloproteinases 1, urinary excretion of EGF, and plasma monocyte chemoattractant protein-1 were measured at each visit.

Results

Seven participants were enrolled, with median baseline urine protein:creatinine ratio 12.1 mg/mg (interquartile range [IQR], 2.2–18.6), serum albumin 2.4 g/dl (IQR, 2.0–2.8), and eGFR 57 ml/min per 1.73 m2 (IQR, 44–96). On the basis of self-report, they received all prescribed doses of adalimumab. The patients with the most favorable response on the basis of changes in urinary biomarkers had the best preserved kidney parenchyma based on urinary excretion of EGF.

Conclusions

Precision medicine trials are feasible in rare glomerular disorders. In this pilot study, adalimumab resulted in a heterogenous response of the candidate mechanistic-predictive biomarkers of TNF-mediated inflammation in patients with FSGS or TR-MCD. A reduction was seen in a subgroup of patients with preserved kidney parenchyma. The findings may reflect the challenge to reverse chronic injury at advanced stages of kidney disease or insufficient intrarenal target engagement with the intervention drug dose.

Clinical Trial registry name and registration number:

NCT04009668 .

Traditional, alternative, and emerging therapeutics for focal segmental glomerulosclerosis

INTRODUCTION

Segmental focal glomerulosclerosis is a histological lesion characterized by podocyte damage. It may be a primary disease linked to an unknown circulating factor, secondary to viral infections, drug toxicity, or a disadaptive response to the loss of nephrons, or it may depend on gene mutations or have an indeterminate cause. The treatment of the primary form involves immunosuppressors. Additional pharmacotherapies for residual proteinuria are used, and emerging therapies are being studied to target other pathological pathways.

AREAS COVERED

This paper covers the treatment of FSGS, focusing on traditional and emerging therapeutic strategies. It is based on the KDIGO 2021 guidelines and supplemented by a literature search conducted on PubMed.

EXPERT OPINION

Treating FSGS is challenging due to its heterogeneity. Immunosuppression is adequate for primary FSGS but harmful in genetic or secondary forms. Key strategies include targeting the underlying cause and using agents that affect renal hemodynamics. Antifibrotic drugs can help slow kidney damage by addressing chronic inflammation and fibrosis. Alongside pharmacological treatments, managing blood pressure and restricting dietary salt are crucial. Finally, personalized treatment requires stratifying patients based on clinical, genetic, and histological data to improve clinical trial design and outcomes.

Sparsentan: the first and only non-immunosuppressive therapy for the reduction of proteinuria in IgA nephropathy

INTRODUCTION

IgA nephropathy is one of the most common forms of glomerular disease. Patients with persistent proteinuria are at increased risk of progression to kidney failure. There is a significant need for safe and effective therapies to lower proteinuria in these patients. Sparsentan is a non-immunosuppressive agent that acts as a dual angiotensin and endothelin receptor antagonist. It lowers proteinuria in experimental models of glomerular disease and in affected patients.

AREAS COVERED

This review covers the immunological and non-immunological actions of sparsentan in glomerular disease. It reviews the clinical trials that evaluated the impact of the drug in pediatric and adult patients with IgA nephropathy. It places the use of sparsentan in an overall treatment paradigm for the full spectrum of patients with IgA nephropathy including nonspecific renoprotective agents such as inhibitors of the renin-angiotensin-aldosterone axis and SGLT2 transporter and immunosuppressive drugs. The review represents a search of the current literature about the effect of the drug on normal physiology and the pathogenesis of IgA nephropathy.

EXPERT OPINION

The safety, tolerability, and therapeutic efficacy of sparsentan have been demonstrated in long-term studies of patients with primary glomerular diseases extending over 5 years. The evidence in support of a beneficial treatment effect of sparsentan is stronger in IgAN than in FSGS. It is anticipated that sparsentan will supplant the use of ACEI or ARB as the first-line therapy to reduce proteinuria prior to the implementation of immunosuppressive agents in patients with IgA nephropathy. It may be combined with other renoprotective drugs like SGLT2 inhibitors. Practice guidelines are needed to promote safe and effective use of this new drug by nephrologists caring for patients with IgAN in all clinical settings.