Emerging drugs for treatment of focal segmental glomerulosclerosis

Impact of Therapeutic Plasma Exchange and Rituximab for Prevention of Idiopathic Focal Segmental Glomerulosclerosis Recurrence Post-Kidney Transplantation

Background

Focal segmental glomerulosclerosis (FSGS) recurs after kidney transplantation (KT) in 30%-50% of recipients. Recurrence is associated with early graft loss in up to 60% of cases. This study aimed to assess the efficacy of therapeutic plasma exchange (TPE) combined with rituximab (RTX) in preventing early FSGS recurrence within 1 y post-KT.

Methods

This single-center, retrospective cohort study included patients receiving KT for idiopathic FSGS between June 2013 and August 2021. In May 2016, a preventative FSGS protocol was implemented where KT recipients with idiopathic FSGS received perioperative sessions of TPE followed by a dose of RTX with or without IVIG. The incidence of recurrent FSGS within the first year posttransplantation was assessed between the FSGS protocol cohort versus the historical group of patients who did not undergo prophylactic treatment.

Results

A total of 65 patients received KT for idiopathic FSGS during the study period. Forty patients were included in the FSGS protocol cohort and 25 in the control cohort. When assessing clinical recurrence with proteinuria, there were significantly fewer cases in the FSGS protocol cohort versus the control cohort, 1 versus 5 patients (3% versus 20%, P = 0.03). There were no instances of death-censored graft loss at 1 y in the protocol cohort versus 2 cases in the control cohort (0% versus 8%, P = 0.14).

Conclusions

TPE combined with RTX may prevent early FSGS recurrence without significant rates of infection.

Pathogenesis of Focal Segmental Glomerulosclerosis and Related Disorders

Focal segmental glomerulosclerosis (FSGS) is the morphologic manifestation of a spectrum of kidney diseases that primarily impact podocytes, cells that create the filtration barrier of the glomerulus. As its name implies, only parts of the kidney and glomeruli are affected, and only a portion of the affected glomerulus may be sclerosed. Although the diagnosis is based primarily on microscopic features, patient stratification relies on clinical data such as proteinuria and etiological criteria. FSGS affects both children and adults and has an elevated risk of progression to end-stage renal disease. The prevalence of FSGS is rising among various populations, and the efficacy of various therapies is limited. Therefore, understanding the pathophysiology of FSGS and developing targeted therapies to address the complex needs of FSGS patients are topics of great interest that are currently being studied across various clinical trials. We discuss the etiology of FSGS, describe the major contributing pathophysiological pathways, and outline emerging therapeutic strategies along with their pitfalls.

Epidemiology and burden of focal segmental glomerulosclerosis among United States Veterans: An analysis of Veteran's Affairs data

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is a rare glomerular disease that can lead to reduced kidney function and kidney failure (KF). The objective of this study was to describe the epidemiology, characteristics, clinical outcomes, healthcare resource utilization, and costs associated with focal segmental glomerulosclerosis (FSGS) in United States (US) veterans.

METHODS

This retrospective cohort study included patients in the National Veterans Affairs Health Care Network with ≥2 FSGS-associated diagnostic codes that were 30-180 days apart (October 1999-February 2021). Annual FSGS incidence and prevalence per 1,000,000 US veterans were calculated. Patient and disease characteristics as of the index date (date of first FSGS diagnosis) and baseline (6-months pre-index) comorbidities were described. Kaplan-Meier analyses were used to assess overall survival and time from index to KF or death, dialysis, and kidney transplant. Post-index medication use, HRU, and direct healthcare costs were summarized.

RESULTS

The study included 2,515 veterans with FSGS who were followed for an average of 8.9 years. The mean age was 57.5 years, most patients were male (94.6%), and the most common comorbidity was hypertension (87.0%). The mean annual incidence and prevalence of FSGS during 2000-2020 were 19.6 and 164.7 per million veterans, respectively. Approximately half (51.5%) died during follow-up (median time: 11.6 years) and 76.9% had kidney failure (4.1 years). Overall, 43.3% underwent dialysis and 5.8% had a kidney transplant. During follow-up, statins and calcium channel blockers were commonly used (81.9% and 75.1%). During the first year post-index, 40% had an inpatient admission and 33% visited the emergency room; mean total healthcare cost per patient in the analysis was $36,543.

CONCLUSIONS

Among US veterans, FSGS is associated with considerable clinical and economic burdens. Better treatments for FSGS are needed to slow kidney disease progression, improve patient outcomes, and reduce the burden.

Focal segmental glomerulosclerosis associated with undescribed mutation in the LMX1B gene

A 50-year-old woman presented with nephrotic proteinuria and preserved glomerular filtration rate. A renal biopsy showed focal segmental glomerulosclerosis (FSGS) and glomerular basement membrane thinning. Her brother has a long history of chronic kidney disease, formerly diagnosed with minimal change disease, and eventually received a kidney allograft, developing high-grade proteinuria and decline in kidney function. FSGS was found by biopsy. Lastly, one paternal uncle suffered from the same condition, but he declined a biopsy. A genetic test identified a novel missense mutation in LMX1B, c.349G > A:p(Gly117Ser). Thus, the present series of cases shows a familial LMX1B-associated nephropathy presenting with FSGS.

Podocyte-targeted therapies - progress and future directions

Podocytes are the key target cells for injury across the spectrum of primary and secondary proteinuric kidney disorders, which account for up to 90% of cases of kidney failure worldwide. Seminal experimental and clinical studies have established a causative link between podocyte depletion and the magnitude of proteinuria in progressive glomerular disease. However, no substantial advances have been made in glomerular disease therapies, and the standard of care for podocytopathies relies on repurposed immunosuppressive drugs. The past two decades have seen a remarkable expansion in understanding of the mechanistic basis of podocyte injury, with prospects increasing for precision-based treatment approaches. Dozens of disease-causing genes with roles in the pathogenesis of clinical podocytopathies have been identified, as well as a number of putative glomerular permeability factors. These achievements, together with the identification of novel targets of podocyte injury, the development of potential approaches to harness the endogenous podocyte regenerative potential of progenitor cell populations, ongoing clinical trials of podocyte-specific pharmacological agents and the development of podocyte-directed drug delivery systems, contribute to an optimistic outlook for the future of glomerular disease therapy.

Rationale and design of the Innsbruck Diabetic Kidney Disease Cohort (IDKDC)-a prospective study investigating etiology and progression of early-stage chronic kidney disease in type 2 diabetes

Background

The development of chronic kidney disease (CKD) in about 20%-40% of patients with type 2 diabetes (T2D) aggravates cardiovascular morbidity and mortality. Pathophysiology is of increasing relevance for individual management and prognosis, though it is largely unknown among T2D patients with CKD as histologic work-up is not routinely performed upon typical clinical presentation. However, as clinical parameters do not appropriately reflect underlying kidney pathology, reluctance regarding timely histologic assessment in T2D patients with CKD should be critically questioned. As the etiology of CKD in T2D is heterogeneous, we aim to assess the prevalence and clinical disease course of typical diabetic vs atypical/non-specific vs non-diabetic vs coexisting kidney pathologies among T2D patients with mild-to-moderate kidney impairment [KDIGO stage G3a/A1-3 or G2/A2-3; i.e. estimated glomerular filtration rate (eGFR) 59-45 mL/min irrespective of albuminuria or eGFR 89-60 mL/min and albuminuria >30 mg/g creatinine].

Methods

The Innsbruck Diabetic Kidney Disease Cohort (IDKDC) study aims to enroll at least 65 T2D patients with mild-to-moderate kidney impairment to undergo a diagnostic kidney biopsy. Six-monthly clinical follow-ups for up to 5 years will provide clinical and laboratory data to assess cardio-renal outcomes. Blood, urine and kidney tissue specimen will be biobanked to identify diagnostic and prognostic biomarkers.

Conclusions

While current risk assessment is primarily based on clinical parameters, our study will provide the scientific background for a potential change of the diagnostic standard towards routine kidney biopsy and clarify its role for individual risk prediction regarding cardio-renal outcome in T2D patients with mild-to-moderate kidney impairment.

Development of a Conceptual Model for the Patient Experience of Focal Segmental Glomerulosclerosis (FSGS): A Qualitative Targeted Literature Review

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is a leading cause of kidney disease and can progress to end stage kidney disease (ESKD). An overview of symptoms and impacts of the disease experienced will help inform the selection or development of fit-for-purpose clinical outcome assessments (COA) to be used in FSGS clinical trials. This study aimed to develop a conceptual model (CM) of the adult and pediatric patient experience of FSGS including disease signs/symptoms, treatment side-effects, and impact on functioning and wellbeing.

METHODS

This study comprised a systematic review and thematic analysis of qualitative studies with adults and pediatric patients diagnosed with FSGS. Data sources were identified through an electronic database search of journal articles (Medline, Embase, PsycINFO; June 2021) and hand-searching of conference proceedings, patient advocacy group websites, and gray literature. Non-English articles were excluded. Identified data (patient/caregiver quotes, author summaries, and interpretations of patient experiences) were extracted from the articles. Extracted data were qualitatively analyzed aided by ATLAS.ti v7. Codes were applied to data and concepts (symptoms/impacts) were identified, named, and refined. A CM was developed by grouping related concepts into domains.

RESULTS

In total, 12 sources were identified for analysis: 6 journal articles and 6 series of patient testimonials. Salient sign/symptom/side-effect domains included swelling/puffiness (edema), pain/aches/discomfort, fatigue, weight changes, skin problems, respiratory problems, and sleep problems. Salient impact domains included emotional/psychological wellbeing, physical functioning/activities of daily living, social functioning, and work/school.

CONCLUSION

Secondary analysis of published qualitative literature permitted development of a CM describing the adult and pediatric experience of FSGS. Concept elicitation interviews are recommended to refine the CM, confirm the salient/most bothersome concepts, and confirm the extent of impact on daily life. The refined CM will provide a useful tool to inform the selection, development, and/or amendment of COAs for use in future FSGS clinical trials.

Implications of Complete Proteinuria Remission at any Time in Focal Segmental Glomerulosclerosis: Sparsentan DUET Trial

Introduction

Focal segmental glomerulosclerosis (FSGS) is a rare glomerular disease with high unmet clinical need. Interest in proteinuria as a surrogate end point for regulatory approval of novel treatments has increased. We assessed the relationship between achieving complete remission (CR) of proteinuria at least once during follow-up and long-term kidney outcomes.

Methods

This post hoc analysis included all patients enrolled in the DUET trial of sparsentan in FSGS and the open-label extension (OLE). Evaluations occurred every 12 weeks, including blood pressure (BP), edema, proteinuria, and kidney function. CR was defined as a urine protein/creatinine ratio ≤0.3g/g in a first morning urine sample.

Results

A total of 108 patients who received ≥1 sparsentan dose were included in this study. During a median follow-up of 47.0 months, 46 patients (43%) experienced ≥1 CR, 61% occurring within 12 months of starting sparsentan. There was an increased likelihood of CR with a higher sparsentan dose or baseline subnephrotic-range proteinuria. Achieving ≥1 CR was associated with significantly slower rate of estimated glomerular filtration rate (eGFR) decline versus non-CR patients (P < 0.05). Use of immunosuppressive agents was more frequent in patients who achieved a CR. However, the antiproteinuric effect of sparsentan was additive to that achieved with concomitant immunosuppressive treatment. No unanticipated adverse events occurred.

Conclusion

We conclude that sparsentan can be safely administered for extended periods and exerts a sustained antiproteinuric effect. Achievement of CR at any time during follow-up, even if it is not sustained, may be an indicator of a favorable response to treatment and a predictor of improved kidney function outcomes.

Protease-activated receptors in kidney diseases: A comprehensive review of pathological roles, therapeutic outcomes and challenges

Studies have demonstrated that protease-activated receptors (PARs) with four subtypes (PAR1-4) are mainly expressed in the renal epithelial, endothelial, and podocyte cells. Some endogenous and urinary proteases, namely thrombin, trypsin, urokinase, and kallikrein released during diseased conditions, are responsible for activating different subtypes of PARs. Each PAR receptor subtype is involved in kidney disease of distinct aetiology. PAR1 and PAR2 have shown differential therapeutic outcomes in rodent models of type-1 and type-2 diabetic kidney diseases due to the distinct etiological basis of each disease type, however such findings need to be confirmed in other diabetic renal injury models. PAR1 and PAR2 blockers have been observed to abolish drug-induced nephrotoxicity in rodents by suppressing tubular inflammation and fibrosis and preventing mitochondrial dysfunction. Notably, PAR2 inhibition improved autophagy and prevented fibrosis, inflammation, and remodeling in the urethral obstruction model. Only the PAR1/4 subtypes have emerged as a therapeutic target for treating experimentally induced nephrotic syndrome, where their respective antibodies attenuated the podocyte apoptosis induced upon thrombin activation. Strikingly PAR2 and PAR4 subtypes involvement has been tested in sepsis-induced acute kidney injury (AKI) and renal ischemia-reperfusion injury models. Thus, more studies are required to delineate the role of other subtypes in the sepsis-AKI model. Evidence suggests that PARs regulate oxidative, inflammatory stress, immune cell activation, fibrosis, autophagic flux, and apoptosis during kidney diseases.

Therapeutic potential of artemisinin and its derivatives in managing kidney diseases

Artemisinin, an antimalarial traditional Chinese herb, is isolated from Artemisia annua. L, and has shown fewer side effects. Several pieces of evidence have demonstrated that artemisinin and its derivatives exhibited therapeutic effects on diseases like malaria, cancer, immune disorders, and inflammatory diseases. Additionally, the antimalarial drugs demonstrated antioxidant and anti-inflammatory activities, regulating the immune system and autophagy and modulating glycolipid metabolism properties, suggesting an alternative for managing kidney disease. This review assessed the pharmacological activities of artemisinin. It summarized the critical outcomes and probable mechanism of artemisinins in treating kidney diseases, including inflammatory, oxidative stress, autophagy, mitochondrial homeostasis, endoplasmic reticulum stress, glycolipid metabolism, insulin resistance, diabetic nephropathy, lupus nephritis, membranous nephropathy, IgA nephropathy, and acute kidney injury, suggesting the therapeutic potential of artemisinin and its derivatives in managing kidney diseases, especially the podocyte-associated kidney diseases.

Integrating network pharmacology approach and experimental validation to reveal the alleviation of Shenkangning capsule on chronic nephritis

ETHNOPHARMACOLOGICAL RELEVANCE

Shenkangning (SKN), a Chinese patent medicine composed by eight Chinese medicinal herbs, is commonly applied to treat chronic glomerulonephritis (CGN) in clinic. However, its mechanism is still not clear now.

AIM OF THE STUDY

This study is designed to evaluate the SKN-provided alleviation on adriamycin (ADR)-induced nephropathy, to reveal its mechanism by integrating network pharmacology analysis and experimental evidences, and to further find the main drug that makes a major contribution to its efficacy.

MATERIALS AND METHODS

ADR was intravenously injected to mice to induce focal segmental glomerulosclerosis (FSGS). Renal histological evaluation was conducted. The level of urinary protein, and serum amounts of creatinine, urea nitrogen (BUN) and albumin were detected. The potential mechanisms were predicted by network pharmacology analysis and further validated by Real-time polymerase chain reaction (RT-PCR), Western-blot and enzyme-linked immunosorbent assay (ELISA).

RESULTS

SKN (1, 10 g/kg) improved ADR-induced nephropathy in mice. Network pharmacology results predicted that inflammation and oxidative stress were crucially involved in the SKN-provided amelioration on nephropathy. SKN reduced the activation of nuclear factor-κB (NF-κB) and the expression of some pro-inflammatory cytokines, and increased the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the expression of its downstream genes in ADR-induced nephropathy in mice. Furthermore, SKN also restored the reduced expression of both podocin and synaptopodin, which are podocyte-associated proteins. Further results showed that the toxic drug Danfupian (DFP) had no contribution to the SKN-provided alleviation on ADR-induced nephropathy in mice. After integrating the results from evaluating anti-inflammation, anti-oxidant and anti-injury of podocytes in vitro and from comparing the activity of the whole SKN and SKN without Astragali Radix (Huangqi, HQ) in vivo, we found that HQ played a crucial contribution to the SKN-provided amelioration on ADR-induced nephropathy in mice.

CONCLUSION

SKN improved ADR-induced nephropathy through suppressing renal inflammation and oxidative stress injury via abrogating NF-κB activation and activating Nrf2 signaling pathway. HQ played a main contribution to the SKN-provided amelioration on ADR-induced nephropathy.

Renal tubular gen e biomarkers identification based on immune infiltrates in focal segmental glomerulosclerosis

OBJECTIVE

The present study identified novel renal tubular biomarkers that may influence the diagnosis and treatment of focal segmental glomerulosclerosis (FSGS) based on immune infiltration.

METHODS

Three FSGS microarray datasets, GSE108112, GSE133288 and GSE121211, were downloaded from the Gene Expression Omnibus (GEO) database. The R statistical software limma package and the combat function of the sva package were applied for preprocessing and to remove the batch effects. Differentially expressed genes (DEGs) between 120 FSGS and 15 control samples were identified with the limma package. Disease Ontology (DO) pathway enrichment analysis was conducted with statistical R software to search for related diseases. Gene set enrichment analysis (GSEA) was used to interpret the gene expression data and it revealed many common biological pathways. A protein-protein interaction (PPI) network was built using the Search Tool for the Retrieval of Interacting Genes (STRING) database, and hub genes were identified by the Cytoscape (version 3.7.2) plug-in CytoHubba. The plug-in Molecular Complex Detection (MCODE) was used to screen hub modules of the PPI network in Cytoscape, while functional analysis of the hub genes and hub nodes involved in the submodule was performed by ClusterProfiler. The least absolute shrinkage and selection operator (LASSO) regression and support vector machine recursive feature elimination (SVM-RFE) analysis were used to screen characteristic genes and build a logistic regression model. Receiver operating characteristic (ROC) curve analyses were used to investigate the logistic regression model and it was then validated by an external dataset GSE125779, which contained 8 FSGS samples and 8 healthy subjects. Cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) was used to calculate the immune infiltration of FSGS samples.

RESULTS

We acquired 179 DEGs, 79 genes with downregulated expression (44.1%) and 100 genes with upregulated expression (55.9%), in the FSGS samples. The DEGs were significantly associated with arteriosclerosis, kidney disease and arteriosclerotic cardiovascular disease. GSEA revealed that these gene sets were significantly enriched in allograft rejection signaling pathways and activation of immune response in biological processes. Fifteen genes were demonstrated to be hub genes by PPI, and three submodules were screened by MCODE linked with FSGS. Analysis by machine learning methodologies identified nuclear receptor subfamily 4 group A member 1 (NR4A1) and dual specificity phosphatase 1 (DUSP1) as sensitive tubular renal biomarkers in the diagnosis of FSGS, and they were selected as hub genes, as well as hub nodes which were enriched in the MAPK signaling pathway. Immune cell infiltration analysis revealed that the genetic biomarkers were both correlated with activated mast cells, which may amplify FSGS biological processes.

CONCLUSION

DUSP1 and NR4A1 were identified as sensitive potential biomarkers in the diagnosis of FSGS. Activated mast cells have a decisive effect on the occurrence and development of FSGS through tubular lesions and tubulointerstitial inflammation, and they are expected to become therapeutic targets in FSGS.

Complete remission of tip lesion variant focal segmental glomerulosclerosis (FSGS) with the Janus Kinase (JAK) inhibitor tofacitinib

A 67-year-old woman with transverse myelitis and seizure disorder secondary to suspected central nervous system (CNS) systemic lupus erythematosus (SLE) and seropositive rheumatoid arthritis had two episodes of severe nephrotic syndrome 15 years apart. She underwent a renal biopsy in both episodes, showing tip lesion variant focal segmental glomerulosclerosis (FSGS). The patient responded both times to prednisone treatment, achieving a complete remission within 2 months in the first episode and remission 4 months in the second episode. A year after her second episode, the patient had a third episode of severe nephrotic syndrome. She achieved an equally rapid complete remission in 3 months without steroid treatment, as she was concomitantly treated with the Janus Kinase (JAK) inhibitor tofacitinib for a flare of rheumatoid arthritis. This case report suggests that JAK inhibitors may have therapeutic use in FSGS, which is supported by experimental data in the medical literature.

Autoimmunity in Focal Segmental Glomerulosclerosis: A Long-Standing Yet Elusive Association

Focal segmental glomerulosclerosis (FSGS) is a histological term that describes a pathologic renal entity affecting both adults and children, with a wide array of possible underlying etiologies. Podocyte damage with scarring, the hallmark of this condition, leads to altered permeability of the glomerular barrier, which may result in massive proteinuria and relentless renal function deterioration. A definite cause of focal segmental glomerulosclerosis can be confirmed in a minority of cases, while most forms have been traditionally labeled as primary or idiopathic. Despite this definition, increasing evidence indicates that primary forms are a heterogenous group rather than a single disease entity: several circulating factors that may affect glomerular permeability have been proposed as potential culprits, and both humoral and cellular immunity have been implicated in the pathogenesis of the disease. Consistently, immunosuppressive drugs are considered as the cornerstone of treatment for primary focal segmental glomerulosclerosis, but response to these agents and long-term outcomes are highly variable. In this review we provide a summary of historical and recent advances on the pathogenesis of primary focal segmental glomerulosclerosis, focusing on implications for its differential diagnosis and treatment.