Pharmacokinetics of rituximab in a pediatric patient with therapy-resistant nephrotic syndrome

Long-term efficacy of Rituximab in steroid dependent and frequent relapsing adult nephrotic syndrome

BACKGROUND

Corticosteroids are highly efficient for treatment of minimal change disease (MCD), however a substantial number of patients become steroid dependent (SD) or frequent relapsing (FR). Response rate is lower in primary Focal Segmental Glomerulosclerosis (FSGS). Since prolonged exposure to corticosteroids should be avoided, an effective alternative is required. Rituximab is a promising agent. We aimed to evaluate the efficacy of Rituximab in adults with SD/FR nephrotic syndrome (NS).

METHODS

A retrospective cohort study, evaluating patients with SD/FR NS treated with Rituximab in a tertiary hospital. Rituximab was given at induction, with additional doses subjected to the treating nephrologist decision. Primary outcome was number of relapses and time to first relapse. Safety was assessed.

RESULTS

Twenty-one adults were included. Among them, 14 (66.7%) were diagnosed with MCD, 5 (23.8%) with FSGS, in 2 cases kidney biopsies were not performed. Median age was 54.6 years. Median follow up was 39.6 months. Number of relapses decreased significantly after Rituximab compared to before treatment (median relapses 0 compared to 3, respectively, W = 3.70, p <.001). Time to first relapse was significantly shorter before Rituximab compared to after (median 11 vs. 536 days, respectively, W = 3.05, p =.002). Hazzard Ratio for relapse was higher in patients who received one Rituximab course compared to those who received an additional maintenance (HR = 4.31, 95% CI: 1.13-16.39, p =.032). Treatment was well-tolerated, serious adverse events included cholecystitis and severe COVID-19.

CONCLUSIONS

Rituximab emerges as an efficient safe steroid sparing in patients with SD/FR NS, with longer remission achieved when an additional maintenance dose is given after the first course.

An international, multi-center study evaluated rituximab therapy in childhood steroid-resistant nephrotic syndrome

The efficacy and safety of rituximab in childhood steroid-resistant nephrotic syndrome (SRNS) remains unclear. Therefore, we conducted a retrospective cohort study at 28 pediatric nephrology centers from 19 countries in Asia, Europe, North America and Oceania to evaluate this. Children with SRNS treated with rituximab were analyzed according to the duration of calcineurin inhibitors (CNIs) treatment before rituximab [6 months or more (CNI-resistant) and under 6 months]. Primary outcome was complete/partial remission (CR/PR) as defined by IPNA/KDIGO guidelines. Secondary outcomes included kidney failure and adverse events. Two-hundred-forty-six children (mean age, 6.9 years; 136 boys; 57% focal segmental glomerulosclerosis, FSGS) were followed a median of 32.4 months after rituximab. All patients were in non-remission before rituximab. (146 and 100 children received CNIs for 6 month or more or under 6 months before rituximab, respectively). In patients with CNI-resistant SRNS, the remission rates (CR/PR) at 3-, 6-, 12- and 24-months were 26% (95% confidence interval 19.3-34.1), 35.6% (28.0-44.0), 35.1% (27.2-43.8) and 39.1% (29.2-49.9), respectively. Twenty-five patients were in PR at 12-months, of which 22 had over 50% reduction in proteinuria from baseline. The remission rates among children treated with CNIs under 6 months before rituximab were 42% (32.3-52.3), 52% (41.8-62.0), 54% (44.3-64.5) and 60% (47.6-71.3) at 3-, 6-, 12-, and 24-months. Upon Kaplan-Meier analysis, non-remission and PR at 12-months after rituximab, compared to CR, were associated with significantly worse kidney survival. Adverse events occurred in 30.5% and most were mild. Thus, rituximab enhances remission in a subset of children with SRNS, is generally safe and CR following rituximab is associated with favorable kidney outcome.

Low serum concentrations of bevacizumab and nivolumab owing to excessive urinary loss in patients with proteinuria: a case series

PURPOSE

Proteinuria can cause interindividual variability in the pharmacokinetics of therapeutic antibodies and may affect therapeutic efficacy. Here, we measured the serum and urinary concentrations of bevacizumab (BV) and nivolumab (NIVO) in patients with proteinuria and reported a case series of these patients.

METHODS

Thirty-two cancer patients who received BV every 3 weeks or NIVO every 2 weeks between November 2020 and September 2021 at Kyoto University Hospital were enrolled in this study. The serum and urinary concentrations of BV and NIVO were measured using liquid chromatography-tandem mass spectrometry.

RESULTS

We divided the BV-treated patients and the NIVO-treated patients into two groups based on the urine protein-creatinine ratio (UPCR): UPCR 1 g/g or higher (BV, n = 9; NIVO, n = 3) and UPCR less than 1 g/g (BV, n = 14; NIVO, n = 6). Serum concentrations of the therapeutic antibodies adjusted by their doses were significantly lower in both BV- and NIVO-treated patients with UPCR 1 g/g or higher compared to those with less than 1 g/g. In patients with UPCR 1 g/g or higher, urinary concentrations of the therapeutic antibodies adjusted by their serum concentrations and urinary creatinine concentrations tended to increase.

CONCLUSION

This case-series study suggests a possibility of reduction in serum concentrations of BV and NIVO in patients with proteinuria by urinary excretion of these drugs.

Efficacy and safety of long-term repeated use of rituximab in pediatric patients with nephrotic syndrome

BACKGROUND

We aimed to investigate the efficacy and safety of repeated use of rituximab (RTX) in pediatric patients with nephrotic syndrome (NS).

METHODS

Retrospective review of 50 patients with steroid-dependent NS (SDNS) who had received more than three cycles of RTX was conducted; each consisted of one to four infusions until B lymphocytes were depleted.

RESULTS

The median age of starting the first RTX cycle was 12.4 years (interquartile ranges (IQR) 10.2-14.6). During a median follow-up period of 6.3 (IQR 3.6-8.6) years, patients received a median of 5.0 RTX cycles (IQR 4.0-7.3). The number of relapses decreased from a median of 2.0 relapses per year (IQR 1.0-3.0) to 0.2 relapses per year (IQR 0.0-0.5) after long-term RTX treatments (P < 0.001). Longer relapse-free periods were associated with more than four RTX cycles, longer B-cell depletion, older age at each RTX treatment, and lower cholesterol levels. B lymphocytes recovered to 1% at a median of 5.9 months (95% confidence interval 5.7-6.1) after RTX administration. Factors related to a longer period of B-cell depletion included more than five RTX cycles, a higher dose of RTX, older age at treatment, and concurrent use of antimetabolites. During repeated RTX treatments, 8.0%, 6.0%, and 2.0% of patients developed hypogammaglobulinemia, severe infection, and severe neutropenia, respectively.

CONCLUSIONS

Long-term repeated use of RTX may be effective and safe in pediatric NS patients. Furthermore, the redosing of RTX could be chosen by considering predictive factors for relapse-free and B-cell depletion periods.

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.

Chapter 3: Management of kidney injury caused by cancer drug therapy, from clinical practice guidelines for the management of kidney injury during anticancer drug therapy 2022

Cisplatin should be administered with diuretics and Magnesium supplementation under adequate hydration to avoid renal impairment. Patients should be evaluated for eGFR (estimated glomerular filtration rate) during the treatment with pemetrexed, as kidney injury has been reported. Pemetrexed should be administered with caution in patients with a CCr (creatinine clearance) < 45 mL/min. Mesna is used to prevent hemorrhagic cystitis in patients receiving ifosfamide. Febuxostat is effective in avoiding hyperuricemia induced by TLS (tumor lysis syndrome). Preventative rasburicase is recommended in high-risk cases of TLS. Thrombotic microangiopathy could be triggered by anticancer drugs and there is no evidence of efficacy of plasma exchange therapy. When proteinuria occurs during treatment with anti-angiogenic agents or multi-kinase inhibitors, dose reductions or interruptions based on grading should be considered. Grade 3 proteinuria and renal dysfunction require urgent intervention, including drug interruption or withdrawal, and referral to a nephrologist should be considered. The first-line drugs used for blood pressure elevation due to anti-angiogenic agents are ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers). The protein binding of drugs and their pharmacokinetics are considerably altered in patients with hypoalbuminemia. The clearance of rituximab is increased in patients with proteinuria, and the correlation with urinary IgG suggests similar pharmacokinetic changes when using other antibody drugs. AIN (acute interstitial nephritis) is the most common cause of ICI (immune checkpoint inhibitor)-related kidney injury that is often treated with steroids. The need for renal biopsy in patients with kidney injury that occurs during treatment with ICI remains controversial.

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.

Implications of rituximab pharmacokinetic and pharmacodynamic alterations in various immune-mediated glomerulopathies and potential anti-CD20 therapy alternatives

The specific B-cell depleting anti-CD20 monoclonal antibody rituximab (RTX) is effective in terms of the treatment of various immune-mediated glomerulopathies. The administration of RTX has been shown to be reliable and highly effective particularly in patients with ANCA-associated vasculitis, which is manifested predominantly with non-nephrotic proteinuria. Stable long-term B-cell depletion is usually readily attained in such patients using standard dosing regimens. However, in patients with nephrotic syndrome and non-selective proteinuria, the RTX pharmacokinetics is altered profoundly and RTX does not maintain high enough levels for a sufficiently long period, which may render RTX treatment ineffective. Since complement-derived cytotoxicity is one of the important modes of action of RTX, hypocomplementemia, frequently associated with systemic lupus erythematodes, may act to hamper the efficacy of RTX in the treatment of patients with lupus nephritis. This review provides a description of RTX pharmacokinetics and pharmacodynamics in several selected glomerulopathies, as well as the impact of proteinuria, anti-drug antibodies and other clinical variables on the clearance and volume of distribution of RTX. The impact of plasmapheresis and peritoneal dialysis on the clearance of RTX is also discussed in the paper. A review is provided of the potential association between pharmacokinetic and pharmacodynamic alterations in various kidney-affecting glomerular diseases, the sustainability of B-cell depletion and the clinical efficacy of RTX, with proposals for potential dosing implications. The role of therapeutic drug monitoring in treatment tailoring is also discussed, and various previously tested RTX dosing schedules are compared in terms of their clinical and laboratory treatment responses. Since alternative anti-CD20 molecules may prove effective in RTX unresponsive patients, their pharmacokinetics, pharmacodynamics and current role in the treatment of glomerulopathies are also mentioned.

Rituximab, Mycophenolic Acid, and Calcineurin Inhibitors Achieve Long-Term Remission in Pediatric Focal Segmental Glomerulosclerosis with Steroid-Resistant and Frequently Relapsing Nephrotic Syndrome: A Report of Two Cases

Studies investigating the effect of rituximab in children with nephrotic syndrome (NS) due to focal segmental glomerulosclerosis (FSGS) have reported conflicting results, with some concluding that patients may require additional immunosuppressive therapy to achieve and/or maintain long-term remission. We report successful treatment of pediatric FSGS with rituximab infusions, followed by maintenance immunosuppression with mycophenolic acid (MPA) and a calcineurin inhibitor (CNI) in 1 patient with refractory steroid-resistant NS (SRNS), and one with frequently relapsing NS (FRNS). Case 1 is a patient with refractory SRNS due to FSGS. MPA and tacrolimus induced complete remission within 6 months following rituximab treatment. Remission was maintained for over 2 years, and the patient's kidney function and body height also returned to normal ranges within this time. Case 2 is a patient with FRNS due to FSGS, who was treated with rituximab followed by MPA and cyclosporine, which successfully prevented relapses for 18 months, that is, at the end point of the observation. Our case report demonstrates that rituximab and a combination of CNIs and MPA can be effective in achieving complete remission in pediatric refractory SRNS and sustaining remission in pediatric FSGS with FRNS and SRNS for several years. This treatment regimen has the advantage of eliminating the need for long-term high-dose steroid treatments, allowing 1 patient to achieve normal growth and recover from other adverse steroid effects.

Rituximab Therapy for Adults with Nephrotic Syndromes: Standard Schedules or B Cell-Targeted Therapy?

Rituximab is a chimeric anti-CD20 monoclonal antibody. It acts mainly through complement-dependent cytotoxicity on B cells expressing the CD20 marker. In this review, we analyse the efficacy and possible pitfalls of rituximab to treat nephrotic syndromes by taking into account pharmacological considerations and CD19 marker testing utility. Despite the fact that the drug has been in use for years, efficacy and treatment schedules in adults with nephrotic syndrome are still a matter of debate. Clinical trials have proven the efficacy and safety of rituximab in idiopathic membranous nephropathy. Data from observational studies also showed the efficacy of rituximab in minimal change disease and focal segmental glomerulosclerosis. Rituximab use is now widely recommended by new Kidney Disease Improved Outcome (KDIGO) guidelines in membranous nephropathy and in frequent-relapsing, steroid-dependent minimal change disease or focal segmental glomerulosclerosis. However, rituximab response has a large interindividual variability. One reason could be that rituximab is lost in the urine at a higher extent in patients with nonselective nephrotic proteinuria, exposing patients to different rituximab plasma levels. Moreover, the association between CD19+ levels and clinical response or relapses is not always present, making the use of this marker in clinical practice complex. High resolution flow cytometry has increased the capability of detecting residual CD19+ B cells. Moreover, it can identify specific B-cell subsets (including IgG-switched memory B cells), which can repopulate at different rates. Its wider use could become a useful tool for better understanding reasons of rituximab failure or avoiding unnecessary retreatments.

Population Pharmacokinetics of Rituximab in Pediatric Patients With Frequent-Relapsing or Steroid-Dependent Nephrotic Syndrome

Objectives: Rituximab is frequently used off-label for the treatment of frequent-relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS), but the relapse rate remained high and the dosing regimen varied widely. The objective of this study was to characterize rituximab pharmacokinetics (PK) in pediatric patients with FRNS/SDNS, and to investigate the differences in rituximab PK between patients with FRNS/SDNS and other disease populations.

Methods: Fourteen pediatric patients received rituximab for FRNS/SDNS treatment were enrolled in a prospective, open-label, single-center PK study. A population PK model of rituximab was developed and validated, and PK parameters were derived for quantitative evaluation.

Results: A two-compartment PK model best described the data. Body surface area was the most significant covariate for both central clearance (CL) and apparent central volume of distribution (V₁). Patients with FRNS/SDNS exhibited a clinically relevant increase in rituximab CL compared to patient population with non-Hodgkin’s lymphoma (NHL).

Conclusion: This pilot study indicated that higher doses or more frequent regimens of rituximab may be required for optimal therapeutic effects in patients with FRNS/SDNS. Further clinical studies with more patients are warranted to confirm this result.

Immune checkpoint inhibitor use in patients with end-stage kidney disease: an analysis of reported cases and literature review

Immune checkpoint inhibitors (ICIs), immunomodulatory antibodies that are used to enhance the immune system, have substantially improved the prognosis of patients with advanced malignancy. As the use of ICI therapy becomes increasingly widespread across different types of cancer, their use in patients receiving dialysis is likely to increase. In this review we summarize the current literature on the use of ICIs in end-stage kidney disease (ESKD) patients and provide aggregate data from reported cases and series. Based on available pharmacological information, ICIs require no dosing adjustment in ESKD patients. Analysis of the reported cases in the literature demonstrates a similar incidence of immune-related adverse events in patients with ESKD receiving dialysis as compared with the general population (49%). Severe reactions graded as 3 and 4 have been seen in 15 patients (16%). As such, it is important that these patients are monitored very closely for immune-related adverse events; however, the risk of these adverse events should not preclude patients on dialysis from receiving these therapies. Cancer remission (complete and partial) was seen in close to 30% of patients, stable disease was seen in 28% and progression of disease in ∼36%. One-third of the patients died. Urothelial and renal cell cancer represented approximately half of all treated cancers and accounted for ∼50% of all deaths reported. Additional data in the dialysis population with the use of ICIs and involvement in prospective studies are needed to better assess outcomes, particularly within specific cancer types.

Effective cholesterol lowering after myocardial infarction in patients with nephrotic syndrome may require a multi-pharmacological approach: a case report

Background

Nephrotic syndrome causes severe hypercholesterolaemia due to increased production and altered clearance of lipoproteins from the liver. It is challenging for patients with nephrotic syndrome and coronary heart disease to meet LDL-cholesterol (LDL-C) goals for secondary prevention with conventional lipid-lowering therapy.

Case summary

We present a man with nephrotic syndrome caused by focal segmental glomerular sclerosis (FSGS) and hypercholesterolaemia. He presented at the emergency room (ER) with an ST-elevation myocardial infarction at the age of 26. On follow-up, the patient had persistent hypercholesterolaemia [LDL-C 3.9 mmol/L and lipoprotein(a) 308 nmol/L] despite a combination of lipid-lowering therapy with atorvastatin 80 mg/day and ezetimibe 10 mg/day. Addition of the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitory antibody evolocumab 140 mg bi-monthly did not improve cholesterol levels. However, after addition of the sodium-glucose cotransporter 2 (SGLT2) inhibitor empagliflozin 10 mg/day on top of other anti-proteinuric treatments, the patient’s proteinuria was reduced and a dramatic drop in LDL-C level by 3.2–0.6 mmol/L (−81%) was observed when evolocumab was re-introduced.

Discussion

We show that target LDL-C levels were obtained in this patient with therapy-resistant FSGS and hypercholesterolaemia following multi-pharmacological treatment with SGLT2 and PCSK9 inhibitors on top of conventional lipid-lowering therapy. The SGLT2-inhibitor reduced proteinuria and, speculatively, also reduced urinary loss of PCSK9-antibody. Therefore, in patients with nephrotic syndrome and cardiovascular disease novel therapeutic options to manage proteinuria could be considered to improve the efficacy of the lipid-lowering therapy, especially when the protein-based PCSK9 inhibitors are used.

[Rituximab treatment in pediatric patients with steroid-dependent nephrotic syndrome: a tertiary hospital]

BACKGROUND

Corticosteroids have had a central role in the treatment of nephrotic syndrome. The management of these patients who become dependent to steroids is complex, involving different immunosuppressive drugs patterns. The monoclonal antibody anti CD20, Rituximab, is likely to have beneficial effects in cases of steroid-dependent nephrotic syndrome patients with no easy resolution, even when we cannot make a statement about the specific role in the impact. We bring our personal experience in pediatric patients treated with this medication during the last years, to provide a thorough overview and useful information about the role of Rituximab in this pathology.

METHODS

Retrospective study in patients with steroid-dependent idiopathic nephrotic syndrome controlled in the division of Pediatric Nephrology of a spanish tertiary hospital in those patients who had received at least one treatment cycle of Rituximab, at any moment along the evolution of the disease.

RESULTS

The study involved 8 patients. All of them previously received immunosuppressive therapy. The Rituximab were administered as an intravenous infusion, in a dose of 375 mg/m2, and all doses were administered in a period during which the disease was in remission. The depletion of lymphocytes B (CD 19%) were confirmed after the first dose of Rituximab except for one, with a lymphocyte count of 1%. The period of depletion lasts 10.3 months (median; range 6.5-16 months), and only one of the patients registered a relapse of the disease in this period. A reduction of relapses suffered by patients has been shown after the treatment began (3.6 relapses/year in the previous year to the start of the treatment vs. 0.1 relapses/year during the first year post-rituximab). The relapse-free survival in the first year reached 83.3% in patients who suffered more than one relapse (75% of patients), and without a relapse after the treatment began in 2 cases. One or more drugs could be removed in 87.5% of patients after the first cycle of rituximab. After the rituximab treatment, we reached a 96.5% decrease in the corticosteroids doses administered (28.5 mg/m2/day during the 3 months pre-treatment vs. 1 mg/m2/day in the last 3 months of patient monitoring). Not a significant observed adverse effect attributed to the drug after the post-rituximab monitoring period (median 46.5 months, range 5-97 months).

CONCLUSION

The favorable results reported after rituximab treatment in our patients seems to confirm the effectiveness of this drug in the steroid-dependent nephrotic syndrome, making that therapeutic option into consideration and legitimating the use of the drug in complex cases involving pediatric patients. Even so, it seems recommendable to design pertinent studies to clarify, among others, the optimum regimen of the treatment (dose, interval and cycles), clinical repercussion and potential adverse effects in long terms.

Daratumumab for systemic AL amyloidosis: prognostic factors and adverse outcome with nephrotic-range albuminuria

Daratumumab has shown promising first results in systemic amyloid light-chain (AL) amyloidosis. We analyzed a consecutive series of 168 patients with advanced AL receiving either daratumumab/dexamethasone (DD, n = 106) or daratumumab/bortezomib/dexamethasone (DVD, n = 62). DD achieved a remission rate (RR) of 64% and a very good hematologic remission (VGHR) rate of 48% after 3 months. Median hematologic event-free survival (hemEFS) was 11.8 months and median overall survival (OS) was 25.6 months. DVD achieved a 66% RR and a 55% VGHR rate. Median hemEFS was 19.1 months and median OS had not been reached. Cardiac organ responses were noted in 22% with DD and 26% with DVD after 6 months. Infectious complications were common (Common Terminology Criteria [CTC] grade 3/4: DD 16%, DVD 18%) and likely related to a high rate of lymphocytopenia (CTC grade 3/4: DD 20%, DVD 17%). On univariable analysis, hyperdiploidy and gain 1q21 conferred an adverse factor for OS and hemEFS with DD, whereas translocation t(11;14) was associated with a better hemEFS. N-terminal prohormone of brain natriuretic peptide &gt;8500 ng/L could not be overcome for survival with each regimen. Multivariable Cox regression analysis revealed plasma cell dyscrasia (difference between serum free light chains [dFLC]) &gt;180 mg/L as an overall strong negative prognostic factor. Additionally, nephrotic-range albuminuria with an albumin-to-creatinine-ratio (ACR) &gt;220 mg/mmol was a significantly adverse factor for hemEFS (hazard ratio, 2.1 and 3.1) with DD and DVD. Daratumumab salvage therapy produced good results and remission rates challenging any therapy in advanced AL. Outcome is adversely influenced by the activity of the underlying plasma cell dyscrasia (dFLC) and nephrotic-range albuminuria (ACR).

Rituximab experience in children with nephrotic syndrome: what have we observed differently

AIM

We aimed to evaluate the efficacy of rituximab therapy in children with nephrotic syndromes and to share our experiences.

MATERIAL AND METHODS

Twelve children with nephrotic syndrome (four with steroid-dependent, eight with steroid-resistant nephrotic syndrome) who were treated with rituximab were retrospectively evaluated in terms of clinical and laboratory data and CD19-20 levels. All patients received rituximab (375 mg/m2) once weekly for 4 weeks. A proteinuria-free period under steroid therapy was not sought prior to initiating rituximab therapy.

RESULTS

The overall remission rates in patients with steroid-dependent and steroid-resistant nephrotic syndrome were 100% and 27%. Focal segmental glomerulosclerosis was diagnosed in six patients and the remission rate was 33% in this population. CD19 cell depletion was observed in 10 of the 12 children. Seven of the 10 patients with CD19 depletion achieved remission, whereas the other three had persistent nephrotic proteinuria despite CD19 depletion. Two patients without CD19 depletion never achieved remission. Relapse occurred in three of the seven patients associated with increased CD19.

CONCLUSION

We observed that rituximab could be given without waiting for a proteinuria-free period under steroid therapy. Our result suggest that administering four weekly doses of rituximab increases the likelihood of remission, considering the amount of drug lost in the urine of children with nephrotic proteinuria. However, our findings must be confirmed with dose-comparison studies conducted with larger populations and an evaluation of long-term adverse effects. Some patients did not achieve remission despite B cell depletion, which suggests that B cell depletion is necessary but insufficient for remission in nephrotic syndromes.

Rituximab therapy for refractory steroid-resistant nephrotic syndrome in children

Patients with steroid-resistant nephrotic syndrome (SRNS) who develop resistance to immunosuppressive agents, defined as refractory SRNS, have poor renal outcomes. Although the chimeric anti-CD20 monoclonal antibody rituximab has shown efficacy for frequently relapsing nephrotic syndrome and steroid-dependent nephrotic syndrome, its efficacy for refractory SRNS remains uncertain due to limited data. According to previous case reports, 50.4% of patients with refractory SRNS showed clinical improvements after rituximab treatment. Remission rates in patients with initial steroid resistance and late steroid resistance were 43.9 and 57.7%, respectively, and 41.5 and 63.6% in patients with focal segmental glomerulosclerosis and minor glomerular abnormalities, respectively. However, various factors (race, disease severity, number of rituximab doses, concomitant treatments, and observation period) differed among these observational studies and their consensus may also have been affected by potential publication bias. Rituximab monotherapy may have some degree of efficacy and lead to satisfactory outcomes in a subset of patients with refractory SRNS. However, administration of concomitant treatments during rituximab-mediated B cell depletion, such as methylprednisolone pulse therapy, daily oral prednisolone therapy, and immunosuppressive agents, may lead to better outcomes in these patients. Large-scale, multi-center prospective studies are needed to evaluate the efficacy and safety of such regimens.

Understanding Inter-Individual Variability in Monoclonal Antibody Disposition

Monoclonal antibodies (mAbs) are currently the largest and most dominant class of therapeutic proteins. Inter-individual variability has been observed for several mAbs; however, an understanding of the underlying mechanisms and factors contributing to inter-subject differences in mAb disposition is still lacking. In this review, we analyze the mechanisms of antibody disposition and the putative mechanistic determinants of inter-individual variability. Results from in vitro, preclinical, and clinical studies were reviewed evaluate the role of the neonatal Fc receptor and Fc gamma receptors (expression and polymorphism), target properties (expression, shedding, turnover, internalization, heterogeneity, polymorphism), and the influence of anti-drug antibodies. Particular attention is given to the influence of co-administered drugs and disease, and to the physiological relevance of covariates identified by population pharmacokinetic modeling, as determinants of variability in mAb pharmacokinetics.

Immune checkpoint inhibitor nephrotoxicity: what do we know and what should we do?

Immune checkpoint inhibitors have dramatically improved cancer therapy for many patients. These humanized monoclonal antibodies against various immune checkpoints (receptors and ligands) effectively treat a number of malignancies by unleashing the immune system to destroy cancer cells. These drugs are not excreted by the kidneys or liver, have a long half-life, and undergo receptor-mediated clearance. Although these agents have greatly improved the prognosis of many cancers, immune-related end organ injury is a complication that has come to light in clinical practice. Although less common than other organ involvement, kidney lesions resulting in acute kidney injury and/or proteinuria are being described. Acute tubulointerstitial nephritis is the most common lesion seen on kidney biopsy, while acute tubular injury and glomerular lesions occur less commonly. Clinical findings and laboratory tests are suboptimal in predicting the underlying renal lesion, making kidney biopsy necessary in the majority of cases to definitely diagnose the lesion and potentially guide therapy. Immune checkpoint inhibitor discontinuation and corticosteroid therapy are recommended for acute tubulointerstitial nephritis. Based on a handful of cases, re-exposure to these drugs in patients who previously developed acute tubulointerstitial nephritis has been mixed. Although it is unclear whether re-exposure is appropriate, it should perhaps be considered in patients with limited options. When this approach is taken, patients should be closely monitored for recurrence of acute kidney injury. Treatment of cancer in patients with a kidney transplant with immune checkpoint inhibitors risks the development of acute rejection in some patients and requires close surveillance.

Plasma infliximab monitoring contributes to optimize Takayasu arteritis treatment: a case report

Background

Infliximab (IFX), a mouse-human chimeric monoclonal antibody against human tumor necrosis factor alpha, is used in refractory cases of Takayasu arteritis. Several factors influence the pharmacokinetics of therapeutic antibodies including IFX. Monitoring plasma levels of IFX could be a useful approach in optimizing treatment via individual dose adjustment.

Case presentation

Here, we report the case of a 4-year-old Takayasu arteritis girl who was resistant to standard therapy. IFX was started at 5 mg/kg (day 0). C-reactive protein (CRP) levels decreased from 8.7 (day 0) to 1.6 mg/dL (day 10). CRP levels were thereafter elevated again on day 23 (9.0 mg/dL), and body fluid leakage at the inflammation site in the legs was observed. Trough IFX levels decreased from 23.6 (day 10) to 2.5 μg/mL (day 23). Based on the trough levels, IFX was given biweekly at 8 mg/kg. Plasma IFX levels gradually increased, and CRP levels decreased to around 2 mg/dL. A similar pattern -initial decreases followed by increases- was observed between clinical course of IFX and IgG levels. It was speculated that IgG and IFX losses were due to fluid leakage from the patient’s necrotizing legs.

Conclusions

Monitoring of plasma IFX levels can be a potential tool to optimize the treatment in Takayasu arteritis patients.

Concentration and Glycoform of Rituximab in Plasma of Patients with B Cell Non-Hodgkin's Lymphoma

PURPOSE

Therapeutic antibodies have heterogeneities in their structures, although its structural alteration in the body is unclear. Here, we analyzed the change of amino acid modifications and carbohydrate chains of rituximab after administration to patients.

METHODS

Twenty B cell non-Hodgkin's lymphoma patients who were treated with rituximab for the first time or after more than one year's abstinence were recruited. Structural analysis of rituximab was carried out at 1 h after administration and at the trough by using liquid chromatography/time-of-flight-mass spectrometry. Plasma rituximab concentration and pharmacodynamic markers were also determined.

RESULTS

Of recruited twenty, 3 patients exhibited rapid rituximab clearance. Nine types of carbohydrate chains were detected in rituximab isolated from the blood. The composition ratios in some glycoforms were significantly different between at 1 h after administration and at the trough, although consisted amino acids remained unchanged. The patients with high clearance showed extensive alterations of glycoform composition ratios. However, pharmacodynamics makers were not different.

CONCLUSION

Inter-individual variations in plasma concentrations of rituximab were found in some B-NHL patients. We could analyze a change in glycoforms of rituximab in the patients, and this finding may affect the pharmacokinetics of rituximab.

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.

Efficacy and safety of rituximab in childhood-onset, difficult-to-treat nephrotic syndrome: A multicenter open-label trial in Korea

BACKGROUND

The anti-CD20 monoclonal antibody rituximab (RTX) has been proposed as a rescue therapy for difficult-to-treat nephrotic syndrome (NS). We conducted a clinical trial to evaluate the efficacy and safety of RTX in children with difficult-to-treat NS dependent on or resistant to steroids and calcineurin inhibitors (CNIs).

METHODS

A multicenter open-label trial was performed at 8 major pediatric nephrology centers in Korea. The investigation consisted of a randomized controlled trial for steroid- and CNI-dependent NS (DDNS; randomization into the RTX group and the control group, at a ratio of 2:1) and a single-arm study of steroid and CNI-resistant NS (DRNS). DDNS patients in the RTX group and DRNS patients received a single dose of intravenous RTX (375 mg/m of body surface area) for B-cell depletion. A second RTX dose was administered at week 2 if the first dose failed to achieve depletion of CD19(+) cells. The primary endpoint was rate of maintaining remission at 6 months after treatment for DDNS and rate of remission achievement for DRNS.

RESULTS

Sixty-one children with DDNS were enrolled while in remission and randomized to the control group (21 patients) or the RTX group (40 patients). At 6 months after treatment, the remission rates were 74.3% in the RTX group and 31.3% in the control group (P = .003). The mean duration of remission maintenance was significantly higher in the RTX group than in the control group (9.0 vs 2.9 months, P = .004). Of the 23 patients with DRNS enrolled in the single-arm study and treated with RTX, 9 (39.1%) achieved partial or complete remission within 6 months. Depletion of B cells occurred in all patients with RTX therapy. Thirty patients (50.8% of 59 patients analyzed) experienced mild and transient infusion reaction during RTX administration, and most adverse events were mild.

CONCLUSIONS

RTX administration was safe and effective in patients with difficult-to-treat NS. One or 2 doses of RTX may be sufficient to deplete B cells and achieve better control of pediatric NS.

Rituximab Exhibits Altered Pharmacokinetics in Patients With Membranous Nephropathy

BACKGROUND

Rituximab (RTX) is a chimeric monoclonal anti-CD20 antibody used off-label in the treatment of membranous nephropathy (MN). Unfortunately, limited information is available on the pharmacokinetics of therapeutic proteins such as RTX in patients with glomerular kidney diseases.

OBJECTIVE

The current study evaluated RTX pharmacokinetics in patients with MN (n = 20) who received 4 RTX weekly intravenous infusions (375 mg/m²) over a month, with a repeat of the identical treatment at 6 months. Baseline patient characteristics were gender (17 male/3 female), age (49 ± 13 years), and body surface area (2.2 ± 0.24 m²).

METHODS

Compartmental pharmacokinetic analyses were conducted using Phoenix, and comparisons of these parameters were made between the MN patients and published data from 2 reference populations without kidney diseases (follicular lymphoma and autoimmune disorders).

RESULTS

Patients with MN exhibited a shorter half-life, reduced volume of central compartment, decreased area under the serum concentration-time curve (exposure), and increased RTX clearance from the central compartment versus previous reports in the reference patient populations.

CONCLUSIONS AND RELEVANCE

These results suggest that shorter half-life and lower exposures to RTX in patients with MN may necessitate higher doses and/or changes to dosing frequency to optimize the relationships between serum concentrations and therapeutic effects.

Rituximab in The Management of Pediatric Steroid-Resistant Nephrotic Syndrome: A Systematic Review

OBJECTIVES

To evaluate the efficacy and safety of rituximab in children with steroid-resistant nephrotic syndrome.

STUDY DESIGN

A systematic review evaluating the efficacy and safety of rituximab in children with steroid-resistant nephrotic syndrome was performed. Data from studies, performed before April 2017 were collected, from MEDLINE, Cochrane Library, Scopus, and Web of Science. Study eligibility criteria included clinical trials and observational studies with a minimal sample size of 5 patients, regarding treatment with rituximab in children with steroid-resistant nephrotic syndrome. Independent extraction of articles by 2 investigators using predefined data fields was performed.

RESULTS

We included 7 case series and 1 open-label randomized controlled trial. Among them, 3 studies were multicenter. A total of 226 patients were included. Mean age at onset was 5.6 ± 1.1 years. Mean number of rituximab administrations was 3.1 ± 1.1 infusions per patient. Remission was observed in 89 patients (46.4%). Remission was seen in 40.8% patients with initial steroid-resistant nephrotic syndrome and 52.8% patients with late steroid-resistant nephrotic syndrome. Good initial response to rituximab therapy was observed in 63.2% patients with minimal change nephrotic syndrome, 39.2% patients with focal and segmental glomerulosclerosis, 1 patient had diffuse mesangial hypercellularity, and 1 patient had IgM nephropathy. Sustained remission ranged from 18% to 93.7%. Five serious adverse events were observed.

CONCLUSIONS

Rituximab exhibited a satisfactory profile regarding efficacy and safety indicating that this agent is a promising therapy for steroid-resistant nephrotic syndrome and should be further investigated by randomized clinical trials.

Pharmacokinetics and safety of panitumumab in a patient with chronic kidney disease

Purpose

Data on panitumumab dosing in cancer patients with renal insufficiency are lacking. Here, we report a 63-year-old metastatic colorectal cancer patient with chronic kidney injury with a glomerular filtration rate of approximately 11 mL/min.

Methods

Pharmacokinetic parameters, including dose-normalized area under the curve, clearance and elimination half-life (T_1/2) after the 11th and 12th infusions were estimated using trapezoidal non-compartmental methods. Data were compared to previous reported pharmacokinetic data from studies in patients with normal renal function.

Results

The results show that the pharmacokinetic data in this patient with kidney failure are comparable to those in patients with adequate renal function. Moreover the treatment was well tolerated in this patient.

Conclusion

This study suggests that panitumumab can be safely used in cancer patients with renal impairment without dose adjustment.

Repeated Administrations of Rituximab along with Steroids and Immunosuppressive Agents in Refractory Steroid-resistant Nephrotic Syndrome

BACKGROUND

A recent randomized control trial in children with steroid-resistant nephrotic syndrome revealed that two doses of rituximab did not reduce proteinuria.

CASE CHARACTERISTICS

A 14-month-old boy developed refractory steroid-resistant nephrotic syndrome due to focal segmental glomerulosclerosis.

OBSERVATION

The patient achieved complete remission 11 months after disease onset following eight doses of rituximab combined with steroids and cyclosporine.

MESSAGE

Long-lasting B cell depletion with repeated rituximab administrations may be required to achieve complete remission in patients with steroid-resistant nephrotic syndrome and massive proteinuria.

Rituximab for immunologic renal disease: What the nephrologist needs to know

Rituximab (RTX), a chimeric, monoclonal anti-CD20 antibody, is increasingly used in immune-mediated renal diseases. While licensed in the induction treatment of ANCA-associated vasculitis, it represents one of the most commonly prescribed off-label drugs. Much of the information regarding its safety has been drawn from experience in hematology and rheumatology. Ample evidence illustrates the safety of RTX, however, rare but serious adverse events have emerged that include progressive multifocal leucoencephalopathy and hepatitis B reactivation. Moderate to severe hypogammaglobulinemia and late-onset neutropenia following RTX therapy confer an increased infectious risk and factors predicting these side effects (i.e. a genetic basis) need to be identified. Nephrologists initiating RTX need to bear in mind that long-term risks and optimal dosing for many renal indications remain unclear. Special considerations must be given when RTX is used in women of childbearing age. We summarize practical aspects concerning the use of RTX. This review will provide nephrologists with information to guide their use of RTX alerting them to safety risks and the need for patient counselling.

Rituximab in Minimal Change Disease: Mechanisms of Action and Hypotheses for Future Studies

Treatment with rituximab, a monoclonal antibody against the B-lymphocyte surface protein CD20, leads to the depletion of B cells. Recently, rituximab was reported to effectively prevent relapses of glucocorticoid-dependent or frequently relapsing minimal change disease (MCD). MCD is thought to be T-cell mediated; how rituximab controls MCD is not understood. In this review, we summarize key clinical studies demonstrating the efficacy of rituximab in idiopathic nephrotic syndrome, mainly MCD. We then discuss immunological features of this disease and potential mechanisms of action of rituximab in its treatment based on what is known about the therapeutic action of rituximab in other immune-mediated disorders. We believe that studies aimed at understanding the mechanisms of action of rituximab in MCD will provide a novel approach to resolve the elusive immune pathophysiology of MCD.

Kinetics of Rituximab Excretion into Urine and Peritoneal Fluid in Two Patients with Nephrotic Syndrome

Clinical observations suggest that treatment of Rituximab might be less effective in patients with nephrotic range proteinuria when compared to nonnephrotic patients. It is conceivable that the reason for this is that significant amounts of Rituximab might be lost in the urine in a nephrotic patient and that these patients require a repeated or higher dosage. However, this has not been systematically studied. In this case report we describe two different patients with nephrotic range proteinuria receiving Rituximab. The first patient received Rituximab for therapy resistant cryoglobulinemic membranoproliferative glomerulonephritis and the other for second line treatment of Felty's syndrome. We employed flow cytometry to determine the amount of Rituximab excretion in both urine and peritoneal fluid specimens in these patients following administration of Rituximab. We found that a significant amount of Rituximab is lost from the circulation by excretion into the urine. Furthermore we saw a close correlation of the excretion of Rituximab to the excretion of IgG molecules suggesting selectivity of proteinuria as the determining factor of Rituximab excretion. Further larger scale clinical studies could have the potential to evaluate an optimal cut-off value of IgG urinary loss before a possible administration of Rituximab therefore contributing to a more individualized treatment approach in patients with nonselective and nephrotic range proteinuria.