Rituximab for Adults With Multi-Drug Resistant Focal Segmental Glomerulosclerosis: A Case Series and Review of the Literature

Rituximab in Steroid-Dependent Podocytopathies

Introduction

Rituximab (RTX) has been reported as an effective treatment alternative in primary forms of minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) associated with steroid dependence and frequent relapses. However, the optimal RTX regimen and the outcomes of further doses of RTX remain unclear. This study aimed to evaluate the use of induction and maintenance RTX therapy for adults with primary podocytopathies.

Methods

We performed a retrospective case series on adult patients with steroid-dependent podocytopathies who received an induction RTX therapy. Maintenance therapy was performed at physician's discretion. Remission and relapse rates, concomitant corticosteroids and immunosuppressants use, B-cell depletion and adverse events were analyzed.

Results

Fourteen patients (mean age at start of RTX 29.1 ± 21.9 years) with MCD (n = 7) or FSGS (n = 7) were treated with 2 doses of 1,000 mg 2 weeks apart (n = 13) or four doses of 375 mg/m2 (n = 1) of RTX. At last follow-up (mean 47.3 ± 101.7 months), 10 patients were in complete remission and two remained in partial remission. A reduction in the number of relapses, number of patients under corticosteroids and immunosuppressants, and dose of prednisolone was observed when compared to baseline (14 [100%] vs. 5 [35.7%]; 8/14 [57.1%] vs. 4/12 [33.3%]; 13/14 [92.9%] vs. 7/12 [58.3%]; 20 mg/day vs. 5.25 mg/day, respectively). Maintenance RTX therapy was used in 6 patients, with sustained complete remission. Infusion reactions were observed in 4 patients (one required treatment withdrawal).

Conclusions

Our findings support the use of RTX for a steroid-free remission in podocytopathies and suggest that maintenance RTX is well-tolerated and associated with prolonged remission. Further studies are needed to confirm its efficacy and safety and establish the optimal induction and maintenance RTX regimen in steroid-dependent podocytopathies.

A New in Silico Antibody Similarity Measure Both Identifies Large Sets of Epitope Binders with Distinct CDRs and Accurately Predicts Off-Target Reactivity

Developing a therapeutic antibody is a long, tedious, and expensive process. Many obstacles need to be overcome, such as biophysical properties (issues of solubility, stability, weak production yields, etc.), as well as cross-reactivity and subsequent toxicity, which are major issues. No in silico method exists today to solve such issues. We hypothesized that if we were able to properly measure the similarity between the CDRs of antibodies (Ab) by considering not only their evolutionary proximity (sequence identity) but also their structural features, we would be able to identify families of Ab recognizing similar epitopes. As a consequence, Ab within the family would share the property to recognize their targets, which would allow (i) to identify off-targets and forecast the cross-reactions, and (ii) to identify new Ab specific for a given target. Testing our method on 238D2, an antagonistic anti-CXCR4 nanobody, we were able to find new nanobodies against CXCR4 and to identify influenza hemagglutinin as an off-target of 238D2.