Anti-rituximab antibodies in pediatric steroid-dependent nephrotic syndrome

Case report: Effective treatment of rituximab-resistant minimal change disease with obinutuzumab in an adult

Background

Minimal change disease (MCD) is a common cause of adult nephrotic syndrome. Most adults with MCD achieve complete remission (CR) after initial steroid therapy. However, approximately 30% of adults who respond to steroids experience frequent relapses, becoming steroid-dependent and potentially developing refractory MCD. Treating refractory MCD in adults poses a significant challenge.

Main body

A 37-year-old woman presented to the nephrology department with a 6-year history of MCD. The diagnosis of MCD was confirmed via renal biopsy. She initially achieved CR with steroid treatment but experienced relapse during steroid tapering. Subsequent CR was achieved with a regimen of steroids and tacrolimus although multiple relapses occurred. Rituximab led to another CR, but its maintenance lasted only 6 months. The response to subsequent rituximab treatments was unsatisfactory. Ultimately, obinutuzumab was selected, resulting in the induction and maintenance of CR for 12 months.

Conclusions

This case demonstrates the successful treatment of frequently relapsed, steroid-dependent, and rituximab-resistant MCD with obinutuzumab. Obinutuzumab is a promising therapeutic option for rituximab-resistant MCD.

Therapeutic drug monitoring in childhood idiopathic nephrotic syndrome: a state of the art review

Immunosuppressants are commonly used as steroid-sparing agents in childhood idiopathic nephrotic syndrome (NS) to induce and sustain remissions. These drugs have narrow therapeutic indices with high inter- and intra-patient variability. Therapeutic drug monitoring (TDM) would therefore be essential to guide the prescription. Multiple factors in NS contribute to additional variability in drug concentrations, especially during relapses. In this article, we review the currently available evidence of TDM in NS and suggest a practical approach for clinicians' reference.

Obinutuzumab in Frequently Relapsing and Steroid-Dependent Nephrotic Syndrome in Children

BACKGROUND

B-cell depletion with rituximab induces sustained remission in children with steroid-dependent or frequently relapsing nephrotic syndrome. However, most patients relapse after B-cell recovery, and some patients do not achieve B-cell depletion. Obinutuzumab is a second-generation anti-CD20 antibody designed to overcome such situations in B-cell malignancies and was recently reported to be safe and effective in other autoimmune diseases affecting the kidneys.

METHODS

We retrospectively report 41 children with steroid-dependent or frequently relapsing nephrotic syndrome treated with a single low-dose infusion of obinutuzumab at Robert-Debre Hospital between April 2018 and December 2020. Participants were treated because of rituximab resistance or relapse after rituximab and received a single infusion of 300 mg/1.73 m 2 obinutuzumab with cessation of oral immunosuppressors within 2 months.

RESULTS

B-cell depletion was achieved in all participants and lasted a median of 8.3 months (interquartile range, 6.4-11.1), a duration exceeding that for last rituximab treatment. At 12 and 24 months, 92% (38/41) and 68% (28/41) of patients, respectively, were in sustained remission. Mild infusion reactions occurred in five participants (12%) and neutropenia in nine (21%). No significant decrease in IgG level was reported during treatment, and whereas IgM levels decreased in 34 patients (83%), they were normal at last follow-up in 32 (78%).

CONCLUSIONS

These results identified low-dose obinituzumab as a promising treatment option in children with steroid-dependent or frequently relapsing nephrotic syndrome, including those resistant to rituximab. The tolerance profile of obinutuzumab was similar to that of rituximab, but hemogram and immunoglobulin levels should be monitored.

Biologics in steroid resistant nephrotic syndrome in childhood: review and new hypothesis-driven treatment

Nephrotic syndrome affects about 2-7 per 100,000 children yearly and accounts for less than 15% of end stage kidney disease. Steroids still represent the cornerstone of therapy achieving remission in 75-90% of the cases The remaining part result as steroid resistant nephrotic syndrome, characterized by the elevated risk of developing end stage kidney disease and frequently presenting disease recurrence in case of kidney transplant. The pathogenesis of nephrotic syndrome is still far to be elucidated, however, efficacy of immune treatments provided the basis to suggest the involvement of the immune system in the pathogenesis of the disease. Based on these substrates, more immune drugs, further than steroids, were administered in steroid resistant nephrotic syndrome, such as antiproliferative and alkylating agents or calcineurin inhibitors. However, such treatments failed in inducing a sustained remission. In last two decades, the developments of monoclonal antibodies, including the anti-CD20 rituximab and inhibitor of B7-1 abatacept, represented a valid opportunity of treatment. However, also the effectiveness of biologics resulted limited. We here propose a new hypothesis-driven treatment based on the combining administration of rituximab with the anti-CD38 monoclonal antibody daratumumab (NCT05704400), sustained by the hypothesis to target the entire B-cells subtypes pool, including the long-lived plasmacells.

Use of Rituximab in Childhood Idiopathic Nephrotic Syndrome

Rituximab is an established therapy in children with idiopathic nephrotic syndrome to sustain short- to medium-term disease remission and avoid steroid toxicities. Recent trials focus on its use as a first-line agent among those with milder disease severity. Rituximab is used in multidrug refractory nephrotic syndrome and post-transplant disease recurrence, although the evidence is much less substantial. Available data suggest that the treatment response to rituximab depends on various patient factors, dosing regimen, and the concomitant use of maintenance immunosuppression. After repeated treatments, patients are found to have an improving response overall with a longer relapse-free period. The drug effect, however, is not permanent, and 80% of patients eventually relapse and many will require an additional course of rituximab. This underpins the importance of understanding the long-term safety profile on repeated treatments. Although rituximab appears to be generally safe, there are concerns about long-term hypogammaglobulinemia, especially in young children. Reliable immunophenotyping and biomarkers are yet to be discovered to predict treatment success, risk of both rare and severe side effects, e.g. , persistent hypogammaglobulinemia, and guiding of redosing strategy. In this review, we highlight recent advances in the use of rituximab for childhood nephrotic syndrome and how the therapeutic landscape is evolving.

Anti-rituximab antibodies in patients with refractory autoimmune nodopathy with anti-neurofascin-155 antibody

Background

Recent studies have reported that similar to other IgG4 autoimmune diseases, such as muscle-specific kinase antibody-associated myasthenia gravis, most anti-neurofascin-155 (anti-NF155) nodopathies respond well to rituximab treatment, regardless of the dosage. However, there are still a few patients for which rituximab is ineffective for unknown reasons. Currently, there are no studies on the mechanism of ineffective treatment with rituximab.

Methods

A 33-year-old Chinese man presenting with numbness, tremor, and muscle weakness for 4 years was recruited for this study. Anti-NF155 antibodies were identified by cell-based assay and confirmed by immunofluorescence assay on teased fibers. The anti-NF155 immunoglobulin (IgG) subclasses were also detected by immunofluorescence assay. Anti-rituximab antibodies (ARAs) were quantitatively analyzed using enzyme-linked immunosorbent assay (ELISA), and peripheral B cell counts were determined by flow cytometry.

Results

The patient exhibited anti-NF155 IgG4-antibody positivity. After the first round of rituximab infusion, the patient showed stratified outcomes with improvements in numbness, muscle weakness and ambulation. However, after three rounds of rituximab infusion, the patient’s symptoms deteriorated, and the numbness, tremor and muscle weakness returned. No obvious improvement was found after plasma exchange and another round of rituximab treatment. 14 days after the last treatment with rituximab, ARAs were detected. And the titers gradually decreased on day 28 and 60 but remained higher than normal. Peripheral CD19+ B cell counts were less than 1% within the 2-month period following the final rituximab administration.

Conclusions

In this study, ARAs presented in a patient with anti-NF155 nodopathy undergoing rituximab treatment and showed an unfavorable impact on rituximab efficacy. This is the first case to report the occurrence of ARAs in patients with anti-NF155 antibodies. We suggest that ARAs should be tested early during the initial intervention, especially in patients who respond poorly to rituximab treatment. In addition, we believe it is necessary to investigate the association between ARAs and B cell counts, their effect on clinical efficacy, and their potential adverse reactions in a larger cohort of patients with anti-NF155 nodopathy.

Sequential rituximab therapy sustains remission of nephrotic syndrome but carries high risk of adverse effects

BACKGROUND

Sequential rituximab (RTX) administration has emerged as an important strategy to sustain remission of disease in patients with difficult-to-treat nephrotic syndrome.

METHODS

We report the efficacy and safety of sequential therapy with two or more courses of intravenous RTX in 250 patients with difficult-to-treat steroid dependence (n = 127) and calcineurin inhibitor (CNI)-dependent or CNI-refractory steroid resistance (n = 123) managed at one center during 2015-2021. Subsets of patients were cross-sectionally tested for hypogammaglobulinemia, seroprotection against and hyporesponsiveness to vaccines for hepatitis B and tetanus, BK/JC viruria and human antichimeric antibodies (HACAs).

RESULTS

Sequential RTX therapy, initiated at a median of 10 years [interquartile range (IQR) 7.3-14.4], was administered for 1.8 courses/person-year [95% confidence interval (CI) 1.7-2.0] over 2.0 years (95% CI 1.2-3.0). Therapy was associated with postponement of relapses by a median of 3 years in patients with steroid-sensitive disease and 2 years in those with steroid resistance. Relapses were reduced by a mean of 2.0 relapses/person-year (95% CI 1.8-2.2), enabling a reduction in prednisolone dose to 0.04 mg/kg/day (95% CI 0.01-0.11) and withdrawal of additional immunosuppression in 154 (62%) patients. RTX-associated adverse events, occurring at 0.20 events/person-year (95% CI 0.17-0.23), were chiefly comprised of infusion reactions (n = 108) and infections (n = 46); serious adverse events were observed in 10.8% patients, at 0.03 events/person-year (95% CI 0.02-0.05). Hypogammaglobulinemia was observed in 35% of 177 patients and was moderate to severe in 8.5% of cases. Rates of seroprotection at baseline and response following vaccination were lower for hepatitis B [1.9% and 29.4% (n = 52)] than tetanus [65.5% and 34.5% (n = 58)]. BK/JC viruria, without viremia, was observed in 7.3% of 109 cases. A total of 19 of 107 patients (17.8%) had HACAs, which were associated with B cell nondepletion and serum sickness. Age at therapy of <9-10 years was associated with a risk of early relapse, treatment failure and hypogammaglobulinemia following RTX therapy.

CONCLUSIONS

Sequential therapy with RTX effectively reduces relapses in patients with difficult-to-treat steroid- and/or CNI-dependent or CNI-refractory nephrotic syndrome. Therapy is associated with high rates of hypogammaglobulinemia and infusion reactions.

Evaluation of Clinical Relevance and Biological Effects of Antirituximab Antibodies in Patients With Pemphigus

Importance

The clinical relevance of antirituximab antibodies (ARAs) in patients with pemphigus who are treated with rituximab (RTX) is currently unknown.

Objective

To determine the prevalence of ARAs in patients with pemphigus who are treated with RTX and their association with complete remission (CR) and relapse.

Design, Setting, and Participants

This post hoc analysis of the Ritux3 trial was conducted from January 2010 to December 2015 in 25 dermatology departments in France and included 42 patients with moderate-to-severe pemphigus who were randomized to receive treatment with RTX. Five additional patients were recruited for an ancillary study. The proportions of patients who achieved CR or relapsed after an initial treatment cycle of RTX were compared depending on whether patients had ARAs.

Exposures

Patients were treated with 1000 mg of RTX on days 1 and 15 and 2 maintenance infusions of 500 mg at months 12 and 18.

Main Outcomes and Measures

Rates of relapse and sustained CR at month 36. Levels of ARAs, antidesmoglein 1/3 antibodies, RTX serum concentrations, and peripheral blood CD19+ B-cell frequency were measured.

Results

Of 42 participants with vs without ARAs, the mean (SD) age was 55 (17) years and 56 (17) years, respectively; 25 (59.5%) were women. Antirituximab antibodies were detected in the serum samples of 13 of 42 patients (31%) during the first year. Nine patients who experienced relapse before month 12 were excluded because they received additional infusions and could not be further analyzed. Among the 33 remaining patients, 2 patients (6.1%) experienced relapse after month 12, and 31 (95.9%) maintained a sustained CR until month 36. The rate of sustained CR was not different whether patients had ARAs (11 of 13 [85%]) or not (20 of 20 [100%]) (P = .15). Both groups (ARA+ vs ARA-) also had similar CD19+ B-cell depletion and RTX levels, but patients with ARAs had higher anti-desmoglein 3 antibody (DSG3 Abs) levels compared with those without ARAs (mean [SD], 30.1 [50.9] AU/mL vs 4.0 [4.3] AU/mL; P = .03). The 2 patients with ARAs who experienced relapse after month 12 had an undetectable RTX level, incomplete B-cell depletion, and higher anti-DSG3 Abs level than the 11 patients who maintained a sustained CR with ARAs (RTX mean [SD] concentration, 0 ug/mL vs 12.5 [2.2] ug/mL; P = .03; incomplete B-cell depletion, 2 of 2 vs 4 of 11; P = .19; mean [SD] anti-DSG3 Abs levels, 103.5 [61.5] AU/mL vs 19.5 [11.0] AU/mL; P = .001) or patients without ARAs (mean [SD] RTX concentration, 0 ug/mL vs 13.5 [1.8] ug/mL; P = .02; incomplete B-cell depletion, 2 of 2 vs 5 of 20; P = .09; mean [SD] anti-DSG3 Abs level, 103.5 [61.5] AU/mL vs 4.0 [1.0] AU/mL; P < .001).

Conclusions and Relevance

The results of this cohort study suggest that ARAs are frequently detected in patients with pemphigus who are treated with RTX and generally are not associated with patient outcomes. Only a few patients with the combination of ARAs, low RTX concentration, incomplete B-cell depletion, and persistent serum anti-DSG3 Abs seem at high risk of relapse.