Eculizumab hepatotoxicity in pediatric aHUS

The efficacy and safety of eculizumab in patients and the role of C5 polymorphisms

Eculizumab is an orphan drug with indications for extremely rare autoimmune disorders. It is primarily prescribed for use in patients with paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome; but is also highly effective in the treatment of myasthenia gravis, among others. By binding to the C5 protein in the complement system, eculizumab effectively inhibits cellular hemolysis and autoimmune reactions. Despite this effective treatment, some patients reported no improvement in symptoms. Genetic sequencing revealed three distinct C5 mutations in the non-responders and these polymorphisms appeared to be most prevalent among Japanese, Korean and African populations. Here, we present an overview of the current and potential future applications of eculizumab, as well as the disadvantages of eculizumab treatment in patients with C5 polymorphisms.

Clinical efficacy and safety of switching from eculizumab to ravulizumab in adult patients with aHUS- real-world data

BACKGROUND

The complement factor 5 (C5)-inhibitor eculizumab has been established as standard-of-care for the treatment of atypical hemolytic uremic syndrome (aHUS). In 2021, the long-acting C5-inhibitor ravulizumab was approved, extending intervals of intravenous treatment from two to eight weeks resulting in improvement of quality of life for patients and lowering direct and indirect therapy associated costs.

METHODS

This multicenter, retrospective data analysis of 32 adult patients with aHUS (including 10 kidney transplant recipients) treated with eculizumab for at least three months and switched to ravulizumab aims to evaluate the safety and efficacy of switching medication in the real-world setting. Hematologic parameters, kidney function, concurrent therapy and aHUS associated events were evaluated three months before and until up to 12 months after switching to ravulizumab.

RESULTS

Mean age (range) at ravulizumab initiation was 41 years (19-78 years) and 59% of the patients were female. Genetic analysis was available for all patients with 72% showing a pathogenic variant. Median time (range) on eculizumab before switching was 20 months (3-120 months). No new events of TMA or worsening of renal function were reported during up to 12 months of follow-up during ravulizumab treatment.

CONCLUSIONS

This is the largest, non-industry derived, multi-center retrospective analysis of adult patients with aHUS switching C5-inhibitor treatment from eculizumab to ravulizumab in the real-world setting. Switching to ravulizumab was safe and efficient resulting in sustained hematological stability and preservation of renal function.

Complement inhibitors in pediatric kidney diseases: new therapeutic opportunities

Historically, the complement system (classical, lectin, alternative, and terminal pathways) is known to play a crucial role in the etiopathogenesis of many kidney diseases. Direct or indirect activation in these settings is revealed by consumption of complement proteins at the serum level and kidney tissue deposition seen by immunofluorescence and electron microscopy. The advent of eculizumab has shown that complement inhibitors may improve the natural history of certain kidney diseases. Since then, the number of available therapeutic molecules and experimental studies on complement inhibition has increased exponentially. In our narrative review, we give a summary of the main complement inhibitors that have completed phase II and phase III studies or are currently used in adult and pediatric nephrology. The relevant full-text works, abstracts, and ongoing trials (clinicaltrials.gov site) are discussed. Data and key clinical features are reported for eculizumab, ravulizumab, crovalimab, avacopan, danicopan, iptacopan, pegcetacoplan, and narsoplimab. Many of these molecules have been shown to be effective in reducing proteinuria and stabilizing kidney function in different complement-mediated kidney diseases. Thanks to their efficacy and target specificity, these novel drugs may radically improve the outcome of complement-mediated kidney diseases, contributing to an improvement in our understanding of their underlying pathophysiology.

C3d-Targeted factor H inhibits tissue complement in disease models and reduces glomerular injury without affecting circulating complement

Complement-mediated diseases can be treated using systemic inhibitors. However, complement components are abundant in circulation, affecting systemic inhibitors' exposure and efficacy. Furthermore, because of complement's essential role in immunity, systemic treatments raise infection risk in patients. To address these challenges, we developed antibody fusion proteins combining the alternative-pathway complement inhibitor factor H (fH1-5) with an anti-C3d monoclonal antibody (C3d-mAb-2fH). Because C3d is deposited at sites of complement activity, this molecule localizes to tissue complement while minimizing circulating complement engagement. These fusion proteins bind to deposited complement in diseased human skin sections and localize to activated complement in a primate skin injury model. We further explored the pharmacology of C3d-mAb-2fH proteins in rodent models with robust tissue complement activation. Doses of C3d-mAb-2fH >1 mg/kg achieved >75% tissue complement inhibition in mouse and rat injury models while avoiding circulating complement blockade. Glomerular-specific complement inhibition reduced proteinuria and preserved podocyte foot-process architecture in rat membranous nephropathy, indicating disease-modifying efficacy. These data indicate that targeting local tissue complement results in durable and efficacious complement blockade in skin and kidney while avoiding systemic inhibition, suggesting broad applicability of this approach in treating a range of complement-mediated diseases.

The cost-effectiveness of pegcetacoplan in complement treatment-naïve adults with paroxysmal nocturnal hemoglobinuria in the USA

Aim: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by hemolytic anemia, bone marrow failure and thrombosis, and is associated with high healthcare burden. We evaluated the cost-effectiveness of pegcetacoplan, a proximal complement-3 inhibitor (C3i), compared with the C5i, eculizumab and ravulizumab, in complement treatment-naive adults with PNH, from the US healthcare payer perspective. Materials & methods: A de novo cost-effectiveness model based on a Markov cohort structure evaluated lifetime (55-year) PNH costs and outcomes. The 6-month cycles of the model reflected the follow-up period of PRINCE (NCT04085601), an open-label trial of pegcetacoplan compared with eculizumab in C5i-naive patients. Data from PRINCE informed the clinical, safety and health-related quality of life outcomes in the model. Results: Pegcetacoplan was associated with lifetime cost savings of USD1,176,808 and USD213,062 relative to eculizumab and ravulizumab, respectively (largely attributed to reduced drug costs and blood transfusions), and additional quality-adjusted life years (QALYs) of 0.25 and 0.24. Conclusion: In patients with PNH who are treatment-naive, the base-case cost-effectiveness analysis, scenario analysis and sensitivity analysis showed both lifetime cost savings and increased QALYs associated with pegcetacoplan compared with eculizumab or ravulizumab in the USA.

Probable eculizumab-associated hepatotoxicity in a patient with neuromyelitis optica: a case report

OBJECTIVES

Neuromyelitis optica (NMO) is an inflammatory, autoimmune and demyelinating disease of the central nervous system and is often characterized by attacks of severe optic neuritis and long segment myelitis. Identifying the disease-specific pathogenic anti-AQP4 autoantibody in NMOSD has allowed the development of highly effective disease-modifying drugs in the treatment phase. Eculizumab is a humanized antibody that binds to complement C5 and inhibits the formation of the C5b-induced membrane attack complex. It is approved for treating many diseases in which tissue damage is accompanied by complement (such as neuromyelitis optica, myasthenia gravis, autoimmune hemolytic anemia and paroxysmal hemoglobinuria).

METHODS

We present a patient diagnosed with NMO who developed possible drug-induced liver injury three months after the start of eculizumab treatment.

RESULT

After discontinuing eculizumab treatment, liver function tests gradually regressed in a month.

CONCLUSIONS

Eculizumab-associated hepatotoxicity is a previously unreported adverse event in NMOSD patients. Therefore, patients should be monitored for liver function tests during eculizumab treatment, and care should be taken for hepatotoxicity. If hepatotoxicity is detected while under eculizumab treatment, patients should be investigated for other drug use, complementary food supplementation, or possible autoimmune hepatitis, and other potential causes should be excluded.

The treatment of atypical hemolytic uremic syndrome with eculizumab in pediatric patients: a systematic review

BACKGROUND

The atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy associated with high morbidity and high mortality. Eculizumab, a humanized anti-C5 monoclonal antibody, was the first medication approved for treating aHUS in 2011.

OBJECTIVE

The objective of this study is to evaluate the efficacy and safety of eculizumab treatment in pediatric patients with aHUS.

DATA SOURCES

We consulted PubMed, Scopus, SciELO, and Cochrane Library databases in July 2021. The descriptors were as follows: "Atypical Hemolytic Uremic Syndrome," "aHUS," "eculizumab," "Pediatrics," "Pediatric," "Child," "Children," "Adolescent."

STUDY ELIGIBILITY CRITERIA

The study eligibility criteria are as follows: clinical trials and observational studies that included pediatric patients with aHUS diagnosis and who were treated with eculizumab.

PARTICIPANTS AND INTERVENTIONS

The participants are pediatric patients, up to 18 years old, with aHUS. The intervention was eculizumab treatment.

STUDY APPRAISAL

For quality assessment, we used the Newcastle-Ottawa Scale, the National Institutes of Health (NIH) quality assessment tool for case series studies, and the Risk of Bias In Non-Randomized Studies of Interventions (ROBINS-I) tool.

RESULTS

The initial search retrieved 433 studies, from which 15 were selected after complete assessment: 9 cohorts, 4 case series, and 1 clinical trial. The publication date ranged from 2015 to 2021. In total, 940 pediatric patients were included, and 682 received eculizumab. All studies reported improvements in renal and hematological parameters in most of the patients treated with eculizumab. The mortality rate was 1.6% for all patients treated with eculizumab.

LIMITATIONS

The number of studies is limited, and the included studies were methodologically heterogeneous. The studies were mostly observational and many had small sample sizes.

CONCLUSIONS

Eculizumab appears to be safe and effective for the treatment of aHUS in pediatric patients. More research is necessary to establish long-term efficacy, safety, and time of discontinuation.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42021266255.

Haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) is a heterogeneous group of diseases that result in a common pathology, thrombotic microangiopathy, which is classically characterised by the triad of non-immune microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. In this Seminar, different causes of HUS are discussed, the most common being Shiga toxin-producing Escherichia coli HUS. Identifying the underlying thrombotic microangiopathy trigger can be challenging but is imperative if patients are to receive personalised disease-specific treatment. The quintessential example is complement-mediated HUS, which once carried an extremely high mortality but is now treated with anti-complement therapies with excellent long-term outcomes. Unfortunately, the high cost of anti-complement therapies all but precludes their use in low-income countries. For many other forms of HUS, targeted therapies are yet to be identified.

Safety and efficacy of pegcetacoplan in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, hematologic disease characterized by complement-mediated hemolysis, thrombosis, and various degrees of bone marrow dysfunction. Until recently, C5 inhibition with eculizumab or ravulizumab represented the only therapies approved for patients with PNH by the United States Food and Drug Administration (US FDA). Although C5-inhibitors reduce PNH-related signs and symptoms, many patients continue to exhibit persistent anemia and require frequent blood transfusions. In May 2021, pegcetacoplan became the third US FDA-approved treatment for adults with PNH, and the first to target C3, a complement component upstream of C5. The novel strategy of inhibiting proximal complement activity with pegcetacoplan controls C5-mediated intravascular hemolysis and prevents C3-mediated extravascular hemolysis. Here, we review the results from multiple pegcetacoplan clinical studies on the efficacy and safety of pegcetacoplan treatment in adults with PNH. This review summarizes findings from three studies in complement-inhibitor-naïve patients with PNH (PADDOCK [phase Ib], PALOMINO [phase IIa], PRINCE [phase III; pegcetacoplan versus standard treatment excluding complement-inhibitors]), and one phase III study (PEGASUS) that compared eculizumab to pegcetacoplan in patients who remained anemic (hemoglobin levels < 10.5 g/dL) despite stable eculizumab treatment (⩾3 months). These studies found that pegcetacoplan contributed to superior improvements in primary and secondary endpoints related to hemoglobin levels and other hematologic parameters and provided effective management of anemia and anemia-related complications (i.e. transfusion burden, reticulocyte production, and fatigue). Furthermore, we summarize results from the 32-week open-label period from the PEGASUS trial, which confirmed the long-term safety and durable efficacy of pegcetacoplan as demonstrated by sustained improvements in clinical and hematologic outcomes in pegcetacoplan-treated patients. Pegcetacoplan is approved for the treatment of adults with PNH in the United States (Empaveli™) and for adult patients who remain anemic after at least 3 months of stable C5-inhibitor therapy in the European Union (Aspaveli®) and Australia (Empaveli; also approved for patients intolerant to C5-inhibitors).

Improving Clinical Trials for Anticomplement Therapies in Complement-Mediated Glomerulopathies: Report of a Scientific Workshop Sponsored by the National Kidney Foundation

Blocking the complement system as a therapeutic strategy has been proposed for numerous glomerular diseases but presents myriad questions and challenges, not the least of which is demonstrating efficacy and safety. In light of these potential issues and because there are an increasing number of anticomplement therapy trials either planned or under way, the National Kidney Foundation facilitated an all-virtual scientific workshop entitled "Improving Clinical Trials for Anti-Complement Therapies in Complement-Mediated Glomerulopathies." Attended by patient representatives and experts in glomerular diseases, complement physiology, and clinical trial design, the aim of this workshop was to develop standards applicable for designing and conducting clinical trials for anticomplement therapies across a wide spectrum of complement-mediated glomerulopathies. Discussions focused on study design, participant risk assessment and mitigation, laboratory measurements and biomarkers to support these studies, and identification of optimal outcome measures to detect benefit, specifically for trials in complement-mediated diseases. This report summarizes the discussions from this workshop and outlines consensus recommendations.

Improved Renal Recovery with Eculizumab Therapy among Children with High Prevalence of Mutation-Associated Atypical Hemolytic Uremic Syndrome: A Retrospective Cohort Study

INTRODUCTION

Genetic defects that determine uncontrolled activation of the alternative complement pathway have been well documented, which account for approximately 40-60% of atypical hemolytic uremic syndrome (aHUS) cases worldwide. In Saudi Arabia, nearly half of the marriages are consanguineous, resulting in a high prevalence of such genetic diseases. Recent studies have demonstrated the effectiveness of eculizumab against aHUS.

OBJECTIVE

We report our experience of using plasma therapy or/and eculizumab to treat children with aHUS in a tertiary care center in Saudi Arabia and to compare their clinical characteristics, genetic mutations, and treatment outcomes.

METHODS

A retrospective cohort study was conducted between January 2010 and May 2017. Data, including demographic parameters, clinical presentation, hospital stay duration, need for dialysis, renal recovery, genetic mutations, and outcomes, were obtained from electronic medical records of all eligible patients.

RESULTS

Overall, 21 children with aHUS were included, of which 12 (57.1%) received eculizumab therapy and 9 (42.9%) received only plasma therapy. End-stage renal disease occurred in 7 children (33.3%), of which 4 (57.1%) received only plasma therapy and 3 (42.9%) received eculizumab therapy whose genetic mutations were not related to the complement dysregulation system. No child who received eculizumab therapy showed recurrence; however, 3 children (33.3%) who received plasma therapy alone showed recurrence. Genetic mutations were detected in 12/20 (60%) of those who underwent genetic screening.

CONCLUSIONS

Children who received eculizumab therapy showed good renal recovery and maintained remission compared with children who received plasma therapy alone. Genetic mutations were detected in 60% of the patients, which was associated with a high prevalence of consanguineous marriages.

Atypical Hemolytic Uremic Syndrome: Cancer-Induced or Chemotherapy-Induced?

Atypical hemolytic uremic syndrome (aHUS) is an atypical type of thrombotic microangiopathy (TMA), which is characterized by microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and thrombi in small blood vessels, leading to end-organ damage. aHUS causes an over-activation of the complement pathway. There are many etiologies of aHUS, including inherited and acquired. This condition has a high mortality rate, as it is often detected late in the disease course. Eculizumab, an inhibitor of the terminal complement pathway, needs to be prescribed as soon as the diagnosis is confirmed. There is limited evidence, however, regarding the duration of treatment. Therefore, it is vital to conduct further analysis on other alternatives and pharmacokinetics with this type of complement inhibitor.

Pharmacology, Pharmacokinetics and Pharmacodynamics of Eculizumab, and Possibilities for an Individualized Approach to Eculizumab

Eculizumab is the first drug approved for the treatment of complement-mediated diseases, and current dosage schedules result in large interindividual drug concentrations. This review provides insight into the pharmacokinetic and pharmacodynamic properties of eculizumab, both for reported on-label (paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, generalized myasthenia gravis) and off-label (hematopoietic stem cell transplantation-associated thrombotic microangiopathy) indications. Furthermore, we discuss the potential of therapeutic drug monitoring to individualize treatment and reduce costs.

Acute Myocarditis and Eculizumab Caused Severe Cholestasis in a 17-Month-Old Child Who Has Hemolytic Uremic Syndrome Associated with Shiga Toxin-Producing Escherichia coli

Cardiovascular involvement is uncommon in pediatric patients with hemolytic uremic syndrome associated with Shiga toxin-producing Escherichia coli (STEC-HUS). In this case report we presented a case of 17-month-old toddler who had a sporadic type of STEC-HUS complicated by acute myocarditis. The patient was successfully treated by a single dose of eculizumab after six doses of therapeutic plasma exchange (TPE) were inefficient to prevent the cardiac complication. Hepatotoxicity was observed after a single dose of eculizumab. Hepatic and cholestatic enzyme levels slowly returned to normal within 6 months. To the best of our knowledge, this is the first case of myocarditis/cardiomyopathy treated with eculizumab in STEC-HUS. This case illustrates the need for vigilance regarding myocardial involvement and eculizumab-induced hepatotoxicity in STEC-HUS.

Complementopathies and precision medicine

The renaissance of complement diagnostics and therapeutics has introduced precision medicine into a widened field of complement-mediated diseases. In particular, complement-mediated diseases (or complementopathies) with ongoing or published clinical trials of complement inhibitors include paroxysmal nocturnal hemoglobinuria, cold agglutinin disease, hemolytic uremic syndrome, nephropathies, HELLP syndrome, transplant-associated thrombotic microangiopathy, antiphospholipid antibody syndrome, myasthenia gravis, and neuromyelitis optica. Recognizing that this field is rapidly expanding, we aim to provide a state-of-the-art review of (a) current understanding of complement biology for the clinician, (b) novel insights into complement with potential applicability to clinical practice, (c) complement in disease across various disciplines (hematology, nephrology, obstetrics, transplantation, rheumatology, and neurology), and (d) the potential future of precision medicine. Better understanding of complement diagnostics and therapeutics will not only facilitate physicians treating patients in clinical practice but also provide the basis for future research toward precision medicine in this field.

Use of complement monoclonal antibody eculizumab in Shiga toxin producing Escherichia coli associated hemolytic uremic syndrome: A review of current evidence

Complement activation plays an important role in the pathogenesis of atypical hemolytic uremic syndrome. Eculizumab is a monoclonal antibody that blocks complement activity and has been approved for use in the treatment of atypical hemolytic uremic syndrome (HUS). Less well appreciated is the role of complement in Shiga toxin-induced HUS (Shiga toxin producing Escherichia coli [STEC]-HUS). To a limited extent, eculizumab has been used off label in patients with severe STEC-HUS with neurological involvement. Through a systematic search of available databases, we identified 16 reports describing the use of eculizumab in STEC-HUS (eight case reports/series, seven retrospective studies, and one prospective cohort study). All studies described its use in severe STEC-HUS with neurological or multiorgan dysfunction; none were randomized or blinded. Four studies used the control groups. Although the overall quality of evidence is low, some published studies showed positive clinical improvement after treatment with eculizumab in severe STEC-HUS with progressive neurological involvement.

Safety and effectiveness of restrictive eculizumab treatment in atypical haemolytic uremic syndrome

Background

Atypical haemolytic uremic syndrome (aHUS) is a rare but severe form of thrombotic microangiopathy as a consequence of complement dysregulation. aHUS has a poor outcome with high mortality and >50% of patients developing end-stage renal disease. Since the end of 2012, these outcomes have greatly improved with the introduction of eculizumab. Currently the duration of treatment is debated. Most guidelines advise lifelong treatment. However, there is no hard evidence to support this advice. Historically, a substantial number of aHUS patients were weaned of plasma therapy, often without disease recurrence. Moreover, the long-term consequences of eculizumab treatment are unknown. In this retrospective study we describe 20 patients who received a restrictive treatment regimen.

Methods

All aHUS patients who presented in the Radboud University Medical Center, Nijmegen, The Netherlands, between 2012 and 2016 and who received eculizumab are described. Clinical, diagnostic and follow-up data were gathered and reviewed.

Results

Twenty patients (14 adults, 6 children) with aHUS have received eculizumab. Eculizumab was tapered in all and stopped in 17 patients. aHUS recurrence occurred in five patients. Due to close monitoring, recurrence was detected early and eculizumab was restarted. No clinical sequela such as proteinuria or progressive kidney dysfunction was detected subsequently. In total, eculizumab has been discontinued in 13 patients without aHUS recurrence, of which 5 are event free for >1 year. With this strategy ∼€11.4 million have been saved.

Conclusions

A restrictive eculizumab regimen in aHUS appears safe and effective. Prospective studies should further evaluate the most optimal treatment strategy.

Eculizumab Safety: Five-Year Experience From the Global Atypical Hemolytic Uremic Syndrome Registry

Introduction

Eculizumab has transformed outcomes for patients with atypical hemolytic uremic syndrome (aHUS). Its efficacy and safety profile was well characterized in the clinical trial program. The long-term safety profile was not previously assessed or compared against nontreated patients in an observational registry setting.

Methods

The Global aHUS Registry recruits patients with clinical diagnoses of aHUS. This analysis includes baseline characteristics and targeted safety events from adult and pediatric patients who were "ever treated" versus "never treated" with eculizumab in the first 5 years of the registry, through January 26, 2017.

Results

Overall, 1321 patients (adult, n = 842; pediatric, n = 479; ever treated, n = 865; never treated, n = 456) were enrolled. A higher proportion of ever-treated versus never-treated adult and pediatric patients had renal, cardiovascular, pulmonary, central nervous system, gastrointestinal symptoms, and hepatic impairment. No differences in safety event rates between ever-treated and never-treated patients were observed, except serious infections in pediatric patients (5.15 versus 1.12 events/100 patient-years for ever- and never-treated patients, respectively). Deaths were more frequent in adult (4.7% and 9.9% of ever- and never-treated patients) compared with pediatric patients (1.8% of ever-treated patients; no deaths in never-treated patients).Three meningococcal infections were reported in ever-treated patients; 1 infection led to a fatal outcome.

Conclusion

In this large observational dataset covering 5 years of registry enrollment, no new safety concerns were identified for adult or pediatric eculizumab-treated patients with aHUS, confirming a positive benefit-risk profile in a real-world setting.

Escherichia coli-associated hemolytic uremic syndrome and severe chronic hepatocellular cholestasis: complication or side effect of eculizumab?

BACKGROUND

Liver lesions of hemolytic uremic syndrome due to Shiga-toxin-producing Escherichia coli (STEC-HUS) are uncommon.

CASE-DIAGNOSIS/TREATMENT

We report three observations of severe STEC-HUS with delayed hepatic involvement. They presented with multiple organ failure and received eculizumab; 15 days after the onset of STEC-HUS, cholestasis appeared and cytolysis worsened. Abdominal ultrasonography showed vesicular sludge. Liver biopsy performed 3 to 6 months after the STEC-HUS found cholangiolar proliferation and inflammatory portal fibrosis. Despite renal recovery, cholestasis persisted and worsened in two cases, leading to biliary cirrhosis and subsequent liver transplantation. Pathological examination of one native liver found thrombotic microangiopathy.

CONCLUSIONS

Even though the pathological examination performed on one native liver demonstrated areas of thrombotic microangiopathy, we cannot completely rule out that eculizumab may have worsened the liver lesions. Before the efficacy of eculizumab in STEC-HUS is formally demonstrated, physicians should stay cautious in its use.

Hyperfunctional complement C3 promotes C5-dependent atypical hemolytic uremic syndrome in mice

Atypical hemolytic uremic syndrome (aHUS) is frequently associated in humans with loss-of-function mutations in complement-regulating proteins or gain-of-function mutations in complement-activating proteins. Thus, aHUS provides an archetypal complement-mediated disease with which to model new therapeutic strategies and treatments. Herein, we show that, when transferred to mice, an aHUS-associated gain-of-function change (D1115N) to the complement-activation protein C3 results in aHUS. Homozygous C3 p.D1115N (C3KI) mice developed spontaneous chronic thrombotic microangiopathy together with hematuria, thrombocytopenia, elevated creatinine, and evidence of hemolysis. Mice with active disease had reduced plasma C3 with C3 fragment and C9 deposition within the kidney. Therapeutic blockade or genetic deletion of C5, a protein downstream of C3 in the complement cascade, protected homozygous C3KI mice from thrombotic microangiopathy and aHUS. Thus, our data provide in vivo modeling evidence that gain-of-function changes in complement C3 drive aHUS. They also show that long-term C5 deficiency is not accompanied by development of other renal complications (such as C3 glomerulopathy) despite sustained dysregulation of C3. Our results suggest that this preclinical model will allow testing of novel complement inhibitors with the aim of developing precisely targeted therapeutics that could have application in many complement-mediated diseases.

Eculizumab in atypical hemolytic uremic syndrome: strategies toward restrictive use

With the introduction of the complement C5-inhibitor eculizumab, a new era was entered for patients with atypical hemolytic uremic syndrome (aHUS). Eculizumab therapy very effectively reversed thrombotic microangiopathy and reduced mortality and morbidity. Initial guidelines suggested lifelong treatment and recommended prophylactic use of eculizumab in aHUS patients receiving a kidney transplant. However, there is little evidence to support lifelong therapy or prophylactic treatment in kidney transplant recipients. Worldwide, there is an ongoing debate regarding the optimal dose and duration of treatment, particularly in view of the high costs and potential side effects of eculizumab. An increasing but still limited number of case reports and small cohort studies suggest that a restrictive treatment regimen is feasible. We review the current literature and focus on the safety and efficacy of restrictive use of eculizumab. Our current treatment protocol is based on restrictive use of eculizumab. Prospective monitoring will provide more definite proof of the feasibility of such restrictive treatment.

Eculizumab prevents thrombotic microangiopathy in patients with atypical haemolytic uraemic syndrome in a long-term observational study

Background

Eculizumab, a terminal complement inhibitor, is approved for atypical haemolytic uraemic syndrome (aHUS) to inhibit complement-mediated thrombotic microangiopathy (TMA).

Methods

In five parent studies, eculizumab effectively prevented TMA and improved renal and haematologic outcomes in patients with aHUS; therefore, these patients could enrol in this long-term, prospective, observational and multicentre study. The primary endpoint was the TMA manifestation rate off and on eculizumab post-parent study. Post hoc analyses evaluated rates during labelled versus non-labelled dosing regimens, and in those with versus without identified complement abnormalities. Serious targeted treatment-emergent adverse events (TEAEs) were evaluated.

Results

Of 87 patients in the current study, 39 and 76 had off- and on-treatment periods, respectively; 17 (44%) with off periods reinitiated eculizumab. TMA manifestation rate per 100 patient-years was 19.9 off and 7.3 on treatment [hazard ratio (HR), 4.7; P = 0.0008]; rates were highest off treatment and lowest during labelled regimens. TMA manifestations with hospitalizations/serious AEs occurred more frequently off versus on treatment. TMA rates were higher among patients with identified complement abnormalities (HR, 4.5; P = 0.0082). Serious targeted TEAEs occurred at similar rates off and on treatment.

Conclusions

As expected, patients with aHUS have increased risk of TMA manifestations after discontinuation of eculizumab or in the setting of non-labelled eculizumab dosing. Collectively, results show that maintaining eculizumab treatment minimizes risk of TMA, particularly in patients with identified complement abnormalities. Future studies are needed to further characterize TMA and longer term outcomes on labelled or non-labelled eculizumab regimens and after discontinuation of treatment.

Thrombotic Microangiopathy and the Kidney

Thrombotic microangiopathy can manifest in a diverse range of diseases and is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ injury, including AKI. It can be associated with significant morbidity and mortality, but a systematic approach to investigation and prompt initiation of supportive management and, in some cases, effective specific treatment can result in good outcomes. This review considers the classification, pathology, epidemiology, characteristics, and pathogenesis of the thrombotic microangiopathies, and outlines a pragmatic approach to diagnosis and management.

Complement C5-inhibiting therapy for the thrombotic microangiopathies: accumulating evidence, but not a panacea

Thrombotic microangiopathy (TMA), characterized by organ injury occurring consequent to severe endothelial damage, can manifest in a diverse range of diseases. In complement-mediated atypical haemolytic uraemic syndrome (aHUS) a primary defect in complement, such as a mutation or autoantibody leading to over activation of the alternative pathway, predisposes to the development of disease, usually following exposure to an environmental trigger. The elucidation of the pathogenesis of aHUS resulted in the successful introduction of the complement inhibitor eculizumab into clinical practice. In other TMAs, although complement activation may be seen, its role in the pathogenesis remains to be confirmed by an interventional trial. Although many case reports in TMAs other than complement-mediated aHUS hint at efficacy, publication bias, concurrent therapies and in some cases the self-limiting nature of disease make broader interpretation difficult. In this article, we will review the evidence for the role of complement inhibition in complement-mediated aHUS and other TMAs.

Long-term remission with eculizumab in atypical haemolytic uraemic syndrome

The understanding of the role of complement dysregulation in atypical haemolytic uraemic syndrome (aHUS) has led to major changes in therapeutic approaches and outcomes. Eculizumab is a humanized anti-C5 monoclonal antibody that inhibits the terminal complement pathway and has revolutionized the treatment and prognosis of aHUS. However, published reports to date have had relatively short-term follow-up. We report two paediatric cases of aHUS successfully treated with eculizumab longer than 6 years with no serious adverse events and preservation of renal function.

Unusual severe case of hemolytic uremic syndrome due to Shiga toxin 2d-producing E. coli O80:H2

BACKGROUND

Hemolytic uremic syndrome (HUS) is one of the most common causes of acute renal failure in children, with the majority of cases caused by an infection with Shiga toxin-producing Escherichia coli (STEC). Whereas O157 is still the predominant STEC serotype, non-O157 serotypes are increasingly associated with STEC-HUS. However, little is known about this emerging and highly diverse group of non-O157 serotypes. With supportive therapy, STEC-HUS is often self-limiting, with occurrence of chronic sequelae in just a small proportion of patients.

CASE DIAGNOSIS/TREATMENT

In this case report, we describe a 16-month-old boy with a highly severe and atypical presentation of STEC-HUS. Despite the presentation with multi-organ failure and extensive involvement of central nervous system due to extensive thrombotic microangiopathy (suggestive of atypical HUS), fecal diagnostics revealed an infection with the rare serotype: shiga toxin 2d-producing STEC O80:H2.

CONCLUSIONS

This report underlines the importance of STEC diagnostic tests in all children with HUS, including those with an atypical presentation, and emphasizes the importance of molecular and serotyping assays to estimate the virulence of an STEC strain.

Monitoring of complement activation biomarkers and eculizumab in complement-mediated renal disorders

Various complement-mediated renal disorders are treated currently with the complement inhibitor eculizumab. By blocking the cleavage of C5, this monoclonal antibody prevents cell damage caused by complement-mediated inflammation. We included 23 patients with atypical haemolytic uraemic syndrome (aHUS, n = 12), C3 glomerulopathies (C3G, n = 9) and acute antibody-mediated renal graft rejection (AMR, n = 2), treated with eculizumab in 12 hospitals in Germany. We explored the course of complement activation biomarkers and the benefit of therapeutic drug monitoring of eculizumab. Complement activation was assessed by analysing the haemolytic complement function of the classical (CH50) and the alternative pathway (APH50), C3 and the activation products C3d, C5a and sC5b-9 prior to, 3 and 6 months after eculizumab treatment. Eculizumab concentrations were determined by a newly established specific enzyme-linked immunosorbent assay (ELISA). Serum eculizumab concentrations up to 1082 μg/ml point to drug accumulation, especially in paediatric patients. Loss of the therapeutic antibody via urine with concentrations up to 56 μg/ml correlated with proteinuria. In aHUS patients, effective complement inhibition was demonstrated by significant reductions of CH50, APH50, C3d and sC5b-9 levels, whereas C5a levels were only reduced significantly after 6 months' treatment. C3G patients presented increased C3d and consistently low C3 levels, reflecting ongoing complement activation and consumption at the C3 level, despite eculizumab treatment. A comprehensive complement analysis together with drug monitoring is required to distinguish mode of complement activation and efficacy of eculizumab treatment in distinct renal disorders. Accumulation of the anti-C5 antibody points to the need for a patient-orientated tailored therapy.

Critical appraisal of eculizumab for atypical hemolytic uremic syndrome

The biology of atypical hemolytic uremic syndrome has been shown to involve inability to limit activation of the alternative complement pathway, with subsequent damage to systemic endothelial beds and the vasculature, resulting in the prototypic findings of a thrombotic microangiopathy. Central to this process is the formation of the terminal membrane attack complex C5b-9. Recently, application of a monoclonal antibody that specifically binds to C5, eculizumab, became available to treat patients with atypical hemolytic uremic syndrome, replacing plasma exchange or infusion as primary therapy. This review focuses on the evidence, based on published clinical trials, case series, and case reports, on the efficacy and safety of this approach.

Eculizumab is a safe and effective treatment in pediatric patients with atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is caused by alternative complement pathway dysregulation, leading to systemic thrombotic microangiopathy (TMA) and severe end-organ damage. Based on 2 prospective studies in mostly adults and retrospective data in children, eculizumab, a terminal complement inhibitor, is approved for aHUS treatment. Here we prospectively evaluated efficacy and safety of weight-based dosing of eculizumab in eligible pediatric patients with aHUS in an open-label phase II study. The primary end point was complete TMA response by 26 weeks. Twenty-two patients (aged 5 months-17 years) were treated; 16 were newly diagnosed, 12 had no prior plasma exchange/infusion during current TMA symptomatology, 11 received baseline dialysis and 2 had prior renal transplants. By week 26, 14 achieved a complete TMA response, 18 achieved hematologic normalization, and 16 had 25% or better improvement in serum creatinine. Plasma exchange/infusion was discontinued in all, and 9 of the 11 patients who required dialysis at baseline discontinued, whereas none initiated new dialysis. Eculizumab was well tolerated; no deaths or meningococcal infections occurred. Bone marrow failure, wrist fracture, and acute respiratory failure were reported as unrelated severe adverse events. Thus, our findings establish the efficacy and safety of eculizumab for pediatric patients with aHUS and are consistent with proposed immediate eculizumab initiation following diagnosis in children.

Drug-induced liver injury in children

PURPOSE OF REVIEW

Drug-induced liver injury (DILI) is an underrecognized cause of pediatric liver disease, accounts for almost 20% of pediatric acute liver failure cases, and is a major reason for liver transplantation in the USA. This article reviews the pathogenesis of DILI, approach to diagnosis and management, and highlights recent pediatric DILI case series.

RECENT FINDINGS

Select individuals have an increased propensity to develop DILI. Known genetic polymorphisms of enzymes and host factors play an important role in medication management and influence the clinical outcome in 20-25% of all drug therapies. Children are more likely to have mitochondrial dysfunction from drugs, increasing their susceptibility to severe liver injury or acute liver failure. Antibiotics and central nervous system agents account for the majority of pediatric DILI in the West, although herbals are becoming more common.

SUMMARY

Clinical features of DILI vary and overlap so exclusion of other conditions, identification of latency period and risk factors, and use of a searchable database can aid evaluation. Treatment consists of cessation of the offending agent and supportive care. Areas needing further research include elucidating mechanisms, identifying at risk individuals, and therapeutic interventions.