Nephrotic Syndrome Study Network

Idiopathic Nephrotic Syndrome (NS) is a rare disease syndrome responsible for approximately 12% of all causes of end-stage kidney disease (ESRD) and up to 20% of ESRD in children. Treatment strategies for Focal and Segmental Glomerulosclerosis (FSGS), Minimal Change Disease (MCD) and Membranous Nephropathy (MN), the major causes of NS, include high dose prolonged steroid therapy, cyclophosphamide, cyclosporine A, tacrolimus, mycophenolate mofetil and other immunosuppressive agents, which all carry significant side effects. Failure to obtain remission using the current treatment approaches frequently results in progression to ESRD with its associated costs, morbidities, and mortality. In the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) registry, half of the pediatric patients with Steroid Resistant Nephrotic Syndrome required renal replacement therapy within two years of being enrolled in the disease registry. FSGS also has a high recurrence rate following kidney transplantation (30-40%) and is the most common recurrent disease leading to allograft loss.

The prevailing classification of Nephrotic Syndrome categorizes patients into FSGS, MCD, and MN, if in the absence of other underlying causes, glomerular histology shows a specific histological pattern. This classification does not adequately predict the heterogeneous natural history of patients with FSGS, MCD, and MN. Major advances in understanding the pathogenesis of FSGS and MCD have come over the last ten years from the identification of several mutated genes responsible for causing Steroid Resistant Nephrotic Syndrome (SRNS) presenting with FSGS or MCD histopathology in humans and model organisms. These functionally distinct genetic disorders can present with indistinguishable FSGS lesions on histology confirming the presence of heterogeneous pathogenic mechanisms under the current histological diagnoses.

The limited understanding of FSGS, MCD, and MN biology in humans has necessitated a descriptive classification system in which heterogeneous disorders are grouped together. This invariably consigns these heterogeneous patients to the same therapeutic approaches, which use blunt immunosuppressive drugs that lack a clear biological basis, are often not beneficial, and are complicated by significant toxicity. The foregoing shortcomings make a strong case that concerted and innovative investigational strategies combining basic science, translational, and clinical methods should be employed to study FSGS, MCD, and MN. It is for these reasons that the Nephrotic Syndrome Study Network is established to conduct clinical and translational research in patients with FSGS/MCD and MN.

Focal Segmental Glomerulosclerosis/Minimal Change Disease (FSGS/MCD) Cohort

Participants enrolled in NEPTUNE with a biopsy proven histological diagnosis for FSGS or MCD.

Eligible participants must be scheduled for a clinically indicated renal biopsy.

Procedure: Kidney Biopsy

Membranous Nephropathy (MN) Cohort

Participants enrolled in NEPTUNE with a biopsy proven histological diagnosis for MN.

Eligible participants must be scheduled for a clinically indicated renal biopsy.

Procedure: Kidney Biopsy

Participants enrolled in NEPTUNE and determined to not have FSGS/MCD or MN will be followed in a third group.

Eligible participants must be scheduled for a clinically indicated renal biopsy.

Procedure: Kidney Biopsy

Participants \< 19 years of age, with \< 30 days exposure to immunosuppression therapy who are not scheduled for renal biopsy.

Patients scheduled to undergo a clinically indicated kidney biopsy will be requested to consent to an additional renal core, to be set aside until all clinical care is complete.

Time frame: 60 months

Defined as remission, partial remission and non-remission

Time frame: 60 months

Defined as:

1. 25 mls/min/1.73m2 reduction in follow-up estimated GFR (using the 4-variable MDRD equation for ages ≥18 years and modified Schwartz for ages \<18 years) compared to baseline estimated GFR
2. 50% decline in follow-up estimated GFR compared to baseline measurement
3. End stage renal disease defined as estimated GFR ≤10cc/min, initiation of maintenance dialysis or preemptive kidney transplantation.

Time frame: 60 months

Patient-reported outcome will be assessed using Quality of Life questionnaires at regular intervals as stipulated in the visit calendar using the SF-36, PedsQL and the Patient Reported Outcome Measurement Information System (PROMIS) (in the age-appropriate groups).

Time frame: 60 months

Any cancer diagnosis of the skin, hematopoietic system, or solid organ after enrollment in NEPTUNE

Time frame: 60 months

Infections including one of the following:

1. Documented diagnosis of infection of the skin or subcutaneous tissue (e.g. cellulitis), vascular system, peritoneum, or any vital organ requiring the use of parenteral antibiotics and/or oral antibiotics alone or in combination for a treatment interval of ≥72 hours.
2. Hospitalization for treatment of infection

Time frame: 60 months

Documented diagnosis of one of the following:

1. Embolic cerebrovascular accident
2. Deep venous thrombosis
3. Renal vein thrombosis or
4. Pulmonary embolus

Time frame: 60 months

Documented hospital admission, including observation for ≥24 hours.

Time frame: 60 months

Documented visit to an emergency department or observation unit that does not lead to hospitalization and is less than 24 hours.

Time frame: 60 months

Documented diagnosis of acute kidney injury as defined by the AKIN (Mehta et al., Critical Care 2007, 11:R31) and/or renal failure requiring renal replacement therapy \<3 months.

Time frame: 60 months

1. Documentation of death that is secondary to infection or sepsis.
2. Cardiovascular/Cerebrovascular-related Death: Sudden death; Myocardial infarction; Congestive heart failure; Primary intractable serious arrhythmia; Peripheral vascular disease; Ischemic cerebrovascular accident; Hemorrhagic cerebrovascular accident; Thromboembolic event
3. Documentation of death secondary to cancer
4. Other Death: Documentation of death that does not fall into the above categories.

Time frame: 60 months

Diagnosis of diabetes as indicated by 1 or more of the following not present at NEPTUNE Enrollment:

1. Documented diagnosis of diabetes in medical record
2. Casual (non-fasting) blood glucose \> 200 mg/dL c) Fasting blood glucose \> 126 mg/dL d) 2 hour glucose \> 200 after oral glucose tolerance test e) chronic use (\>6 mos) hypoglycemic therapy outside of pregnancy f) Hemogloblin A1C \>= 6.5%

Nephrotic Syndrome Study Network Under the Rare Diseases Clinical Research Network