Single dose of rituximab in children with steroid-dependent minimal change nephrotic syndrome

Rituximab Use for the Treatment of Childhood Nephrotic Syndrome by Canadian Pediatric Nephrologists: A National Survey

Background:

There is known practice variation in the treatment of frequently relapsing, steroid-dependent, and steroid-resistant nephrotic syndrome in children. Rituximab is an emerging therapy for difficult-to-treat nephrotic syndrome; however, there are no clear treatment guidelines. We therefore hypothesized that a wide variety of approaches to this therapy exist.

Objective:

To evaluate when and how rituximab is used for the treatment of childhood nephrotic syndrome in Canada.

Design and setting:

An online survey was used.

Participants:

Canadian pediatric nephrologists.

Methods:

A cross-sectional survey was distributed across Canada through the Canadian Association of Pediatric Nephrologists (CAPN) to evaluate rituximab treatment practices.

Results:

Of a total of 20 responses, 19 (95%) use rituximab in the treatment of nephrotic syndrome, usually as a third or fourth agent. For the number of rituximab doses, the majority (68%) uses 2 doses each time they use it. Eighteen respondents (90%) measure B cells when using this medication, mostly monthly (50%) or every 3 months (39%). Respondents were administered additional doses of rituximab prophylactically (74%) or at first relapse (47%). Long-term drug safety and drug funding were identified as the main barriers to rituximab use.

Limitations:

This survey represents the practice styles of physicians in a single country, and there is a nonresponse bias of 63%. Also, associations were not calculated.

Conclusions:

Among Canadian pediatric nephrologists, rituximab use for nephrotic syndrome appears to be increasing, but significant practice variations remain, including approaches to B-cell monitoring. It is reserved mostly for second-line and third-line use due to cost, funding issues, and residual uncertainty regarding long-term safety. Understanding these critical areas of practice uncertainty is a first step to optimize treatment of nephrotic syndrome in children.

Low-dose rituximab is no less effective for nephrotic syndrome measured by 12-month outcome

OBJECTIVE

Rituximab is an effective treatment for children with steroid dependent or frequently relapsing nephrotic syndrome. The optimum dosing schedule for rituximab has not been established. We hypothesized that a single low dose of 375 mg/m² would have comparable outcomes to higher doses in reducing the frequency of relapse and time to B cell reconstitution.

METHODS

We conducted a multicenter retrospective observational cohort study of children with steroid-sensitive frequently relapsing nephrotic syndrome. Data were extracted from clinical records including the dates of diagnosis, treatment, relapses, the use of concomitant immunosuppression, and lymphocyte subset profiling. Patients treated earlier received variable doses of rituximab, although typically two doses of 750 mg/m². Later, patients received the current regimen of a single dose of 375 mg/m². The primary outcome was an absence of clinically confirmed relapse 12 months following rituximab administration. Secondary outcomes were median time to relapse, probability of being relapse-free at 6 and 24 months and time to reconstitution of CD19⁺ B cells.

RESULTS

Sixty patients received 143 courses of rituximab. Seven different dosing regimen strategies were used, ranging between 375 and 750 mg/m² per dose, with administration of 1-4 doses. There was no significant difference in event-free survival at 12 months between dosing strategies. The median time to reconstitution of B cells was not significantly different between groups.

CONCLUSIONS

Use of a single low-dose regimen of rituximab in the management of frequently relapsing nephrotic syndrome does not affect the probability of relapse at 12 months or time to B cell reconstitution compared to a conventional higher dose.

Rituximab Use in the Management of Childhood Nephrotic Syndrome

Childhood nephrotic syndrome is a challenging and often persistent renal disorder, and its incidence varies between different ethnicities and regions. Corticosteroids have been the main treatment for decades and are effective in most children with idiopathic NS, although 10-15% of these children become steroid resistant. Furthermore, some initially steroid sensitive children follow a steroid dependent or frequently relapsing course and are therefore at increased risk for developing steroid toxicity. In such children, alternative immunosuppressive medications are used to induce and/or maintain remission of NS. One such drug, rituximab, is a monoclonal antibody directed against the B lymphocyte CD20 marker which induces depletion of B cells, and has shown promising results in the management of NS in children. In this review, we summarize recent studies on the efficacy and safety of rituximab in the different types of childhood nephrotic syndrome, the known and potential mechanisms of action of rituximab, its possible complications and side effects, and the available and potential biomarkers of rituximab activity.

Cost analysis on the use of rituximab and calcineurin inhibitors in children and adolescents with steroid-dependent nephrotic syndrome

BACKGROUND

Rituximab (RTX) is increasingly being used in place of calcineurin inhibitors (CNI) in pediatric patients with steroid-dependent nephrotic syndrome (SDNS). However, despite its favorable safety profile, its unit cost is prohibitive. We therefore compared the healthcare costs associated with the use of both agents in a retrospective cohort.

METHODS

This study was a retrospective analysis of data retrieved from the medical charts and electronic databases of pediatric patients (age range 2-18 years) with SDNS who were treated with either CNI or RTX from January 2008 to December 2012 at Children's Hospital of New Orleans, Louisiana. The minimum follow-up period was 12 months.

RESULTS

Of the 18 patients whose medical data were analyzed, ten received RTX and eight were treated with CNI. The annualized healthcare cost for the rituximab group was $197,031 versus $189,857 (all values in US dollars) for the CNI group (p > 0.05). At the 12-month follow-up, more patients in the RTX group were in remission (40 vs. 25%). Duration of freedom from steroid use was longer in the RTX group, while body mass index was higher in the CNI arm (p > 0.05). No significant adverse events occurred in either group.

CONCLUSION

The expenditure for the RTX and CNI groups was comparable, but there were fewer clinical encounters in the former group, potentially reducing the burden of healthcare on the patient's family.

Infectious complications of rituximab therapy in renal disease

Rituximab, an anti-CD20 monoclonal antibody, was originally used to treat B-cell malignancies. Its use has significantly increased in recent years, as it is now also used to treat a variety of autoimmune diseases including rheumatoid arthritis and ANCA-associated vasculitis (AAV). Initial studies suggested that the adverse effects of rituximab were minimal. Though the risk of malignancy with rituximab-based immunosuppressive regimens appears similar to that of the general population, there are now concerns regarding the risk of infectious complications. Rituximab has been associated with serious infections, including Pneumocystis jiroveci pneumonia (PJP) and the reactivation of hepatitis B virus (HBV) and tuberculosis (TB). The risk of infection appears to be the result of a variety of mechanisms, including prolonged B-cell depletion, B-cell–T-cell crosstalk, panhypogammaglobulinaemia, late-onset neutropenia and blunting of the immune response after vaccination. Importantly, the risk of infectious complications is also related to individual patient characteristics and the indication for rituximab. Individualization of treatment is, therefore, crucial. Particular attention should be given to strategies to minimize the risk of infectious complications, including vaccinating against bacterial and viral pathogens, monitoring white cell count and immunoglobulin levels, prophylaxis against PJP and screening for HBV and TB.