Our study reinforces the role of rituximab as a GC-sparing agent in the challenging GC-dependent and multirelapsing MCD patients. In this emerging therapeutic field randomized studies with extended follow-up will add important information regarding optimal treatment, relapse and safety.

Minimal-change nephropathy (MCN) accounts for 10-15% of cases of the nephrotic syndrome in adults. Frequent relapses occur in 10-25% of cases and steroid dependence is seen in 25-30%. Rituximab is a chimeric mono-clonal antibody directed against CD20-positive Bcells with reported benefit in immune-mediated renal disease. We present six female and three male patients, ranging from 27-70 years of age, with multirelapsing, steroid-dependant or steroid-resistant MCN, with previous multiple courses of cortico-steroids (CS) and secondline therapies. Five patients were steroid dependant with the lowest daily CS dose between 5-20 mg/day. All patients were given two doses of rituximab, each a flat dose of 500 mg except for one case who received a dose of 1000 mg. All patients were B-cell depleted before the second dose. No major side effects occurred. Seven of the patients responded to therapy with normalized plasma albumin and no albuminuria enabling discontinuation or tapering of CS significantly below levels where relapses had occurred in the past (P=0.03). One patient reached partial remission and another had no response to therapy. Follow-up was 6-33 months. There were three relapses after 9, 12, and 20 months, respectively. In conclusion, frequency of relapses and steroid dependency or resistance in MCN remain therapeutic challenges to physicians. The current case series suggests that B-cell depletion may induce long-lasting remissions and, as a result, has a potential as a steroid-sparing agent in the treatment of steroid-dependent and multirelapsing MCN patients.This work is licensed under a Creative Commons Attribution 3.0 License (by-nc 3.0) ©Copyright A. Bruchfeld et al. 2010

Background and Aims Preventing hyperkalemia - a potentially fatal complication in advanced CKD - by prescribing diets low in K (=limited intake of healthy components such as vegetables, fruits, whole grains and nuts) leads to poor dietary quality. K-restricted unhealthy diets may affect quality of life, patient satisfaction with treatment, achievement of nutritional targets, and increase risk of obstipation, gut dysbiosis and progression of CKD. We designed a feasibility study to test if a low-protein healthy K-rich diet with fruits, vegetables, whole grains and nuts with concomitant use of new potassium binder (SZC) can be safely prescribed to patients with CKD stages 4 and 5 with hyperkalemia. Method A feasibility descriptive single arm open-label interventional trial lasting 6 weeks will enroll 36 CKD patients at the outpatient clinic with: age 18 - 85 years; glomerular filtration rate < 29 ml/min/1.73 m2 and not on dialysis; serum K > 5.1 mmol/L or in previous use of sodium polystyrene sulfonate (SPS) to decrease serum K levels, and who develops hyperkalemia after SPS is ceased. Patients with serum K > 6.5 mmol/L and those likely to start dialysis within 2 months, with inflammatory bowel syndrome or with a history of hypokalemia (<3.0 mmol/L) will not be included. Primary end points will be changes in patient satisfaction with treatment, patient symptom list, and intake of energy and protein before and after the stabilization and healthy diet phase. Secondary outcomes will include changes in quality of life, obstipation and circulating gut microbiota-related uremic toxins. Intervention: In the first 3 weeks, representing stabilization phase, SZC will be prescribed to normalize serum K to 3.5 to 5.0 mml/L, and a diet with energy 25-35 kcal/kg/day and protein 0.6 to 0.8 g/kg/day and with low K content will be prescribed by a renal dietitian. At the end of the first 3 weeks, the patients will be instructed to keep the same content of energy and protein and initiate a healthy diet containing 3700 to 4000 mg/potassium for 3 weeks (healthy diet phase). In order to increase adherence, a food basket containing fruits, vegetables, whole grains, nuts, white meat, fish and eggs in amounts adequate for the patient and the family will be provided. Serum K will be monitored to promote serum K between 3.5 to 5.0 mmol/L and adjustments in the dose of SZC will be performed according to the drug label. Blood measurements, quality of life and intestinal obstipation questionnaires and measurements of nutritional intake will be performed in the beginning and at the end of the stabilization phase and again in the beginning and end of the healthy diet phase. Additionally, during stabilization and healthy diet phases, serum K will be measured every 72 hours until serum K is normalized and after that, once per week. The protocol is registered at www.clinicaltrials.gov (identifier NCT04207203). Results NA Conclusion This interventional feasibility pilot study will test the hypothesis that - with precautions aiming at reducing risk of hyperkalemia - a K-rich healthy diet in patients with CKD stage 4 may improve patient satisfaction with treatment and patient symptoms. Depending on the results, a larger randomized controlled longitudinal trial will be considered to investigate if K-rich diet in CKD stage 4-5 patients is safe and beneficial.