Rituximab in Multirelapsing Minimal Change Disease (MCD) or Focal Segmental Glomerulosclerosis (FSGS)

BACKGROUND Nephrotic syndrome (NS)affects 2 every 100,000 children younger than 16 years. Minimal change disease (MCD) accounts for around 90 percent of cases and most of the remaining ones are associated with focal segmental glomerulosclerosis (FSGS). Patients with NS are at increased risk for life-threatening infections and thromboembolic episodes, and are often affected by dyslipidemia and osteoporosis. Glucocorticoids are first-line treatment and may achieve remission in about 90% of patients with MCD and in 20 to 60% of those with FSGS. In about 20% to 60% of those achieving remission, however, steroid withdrawal is followed by a recurrence of the disease. These patients require chronic steroid therapy (steroid-dependent cases): this prevents relapses in most cases but is invariably associated with severe adverse effects including growth retardation, infections, malignancies, hypertension, impaired glucose tolerance, weight gain and somatic changes. In a small proportion of patients, recurrences occur even under chronic steroid therapy (multirelapsing cases). In these cases, several approaches have been used to control disease activity including plasmapheresis and add-on therapy with cyclophosphamide, cyclosporine, mycophenolate mofetil and other immunosuppressants. Chronic immunosuppression, however, seldom achieves persistent remission and is invariably burdened by serious adverse effects including gonadotoxicity and sterility, opportunistic infections, malignancies, bone marrow depression and renal toxicity. Thus, safer and more effective treatments are urgently needed for these patients.

Rituximab, a chimeric monoclonal antibody targeted to the CD20 antigen of B cells able to induce antibody-dependent and complement-mediated lysis of these cells, has been reported to be effective in children with NS secondary to MCD or FSGS unresponsive to other immunosuppressive treatments. Rituximab achieved persistent NS remission in a patient with MCD diagnosed at age of 30 yrs who had a history of frequent relapses refractory to treatment with other immunosuppressants. Thus, chronic MCD persisting into adult-years may respond to rituximab and sustained remissions are possible despite long-term disease and after other treatments have failed. Along the same line, rituximab achieved prompt and persistent remission in an adult with steroid and mycophenolate mofetil-resistant MCD and in two patients with FSGS and steroid-resistant NS.

The above findings suggest that rituximab may have a role in the treatment of patients who require chronic exposure to steroids and/or other immunosuppressants to prevent or limit disease reactivation. Thus, main goal of the present study is to assess whether rituximab administration may allow tapering and withdrawing ongoing treatment without exposing the patients to the risk of disease recurrence.

AIMS Primary

• To evaluate whether Rituximab therapy is able to prevent NS recurrence after complete withdrawal of steroids and other immunosuppressive treatments in patients with steroid-dependant or multirelapsing NS on sustained remission for at least 1 month.

Secondary

• To assess whether Rituximab therapy may reduce the need for steroids and other immunosuppressive agents to prevent and treat further disease relapses;
• To evaluate whether tapering or withdrawal of immunosuppressant therapy is associated with regression of the related toxicities, such as growth retardation, hypertension, impaired glucose tolerance and dyslipidemia;
• To assess whether persistent NS remission is associated with an improvement of kidney function and of renal hemodynamics;
• To study whether proteinuria remission is associated with the disappearance of albumin permeability factor(s) from patient's sera;
• To assess the safety profile of the rituximab treatment;
• To evaluate the cost/effectiveness of the study treatment.