An audit analysis of a guideline for the investigation and initial therapy of diarrhea negative (atypical) hemolytic uremic syndrome

A Case of Atypical Hemolytic Uremic Syndrome With a Complement Factor I Mutation Triggered by a Femoral Neck Fracture

Atypical hemolytic uremic syndrome is a thrombotic microangiopathy caused by the abnormal activation of the alternative complement pathway. Mutations in complement-related genes and autoantibodies against complement regulators are involved in the pathogenesis of this condition; the frequency of, and prognosis of patients harbouring, each genetic mutation varies based on the region and race. Complement factor I (CFI) mutations have been observed in 4%-8% of cases in Europe; however, they have not yet been reported in Japan. We present the first Japanese case of atypical hemolytic uremic syndrome in a patient harbouring a CFI mutation. An 83-year-old female patient presented with severe acute kidney injury, thrombocytopenia, and hemolytic anaemia following a femoral neck fracture. Plasma exchange and haemodialysis were initiated, resulting in improved kidney function and platelet count. However, the platelet count decreased when plasma exchange was discontinued. Therefore, we administered ravulizumab, an anti-complement 5 monoclonal antibody, which led to the maintenance of stable kidney function and platelet count. Genetic analysis revealed a CFI mutation, and the patient was treated with ravulizumab for 2 years without relapse. Individuals diagnosed with atypical hemolytic uremic syndrome harbouring CFI mutations experience poor outcomes, including low rates of remission, high rates of mortality, and progression to end-stage kidney disease. Our case serves as a crucial example demonstrating how prompt identification and appropriate management can lead to better patient outcomes.

Updates in atypical hemolytic syndrome

PURPOSE OF REVIEW

This review aims to summarize how scientific advances in complement biology have not only improved the diagnosis and management of aHUS but also continue to offer insights into the pathophysiology of complement-mediated disease that may be leveraged for future therapeutic developments.

RECENT FINDINGS

Updated information on the clinical and epidemiological features, pathophysiology, diagnosis, management, and potential for future therapeutic advancements in the treatment of aHUS are reviewed.

SUMMARY

aHUS is a rare but potentially life-threatening disease that requires prompt diagnosis and treatment as well as long-term management via a multidisciplinary team providing coordination of primary and specialty care as well as outreach and education for children and families affected by this life-long disease.

Extrarenal manifestations of atypical hemolytic uremic syndrome: a systematic review and meta-analysis

BACKGROUND

Atypical Hemolytic Uremic Syndrome (aHUS) is categorized as a thrombotic microangiopathy (TMA), which arises due to abnormal or unregulated complement pathway activation. While the disease frequently affects renal blood vessels, it can also involve multiple other organ systems. This review examines the prevalence and clinical outcomes of aHUS patients with extrarenal involvement.

METHODS

A comprehensive literature search was performed using PubMed/Medline, Embase, the Web of Science Core Collection, and CINAHL. Search terms included 'aHUS', 'extrarenal', and specific organ systems such as neurological, gastrointestinal, and cardiovascular. Patient data was collected on clinical characteristics, including extrarenal symptoms, lab findings, genetic mutations, and adverse events. Meta-analysis was conducted using R software, version 3.1.0.

RESULTS

A total of 47 studies were reviewed, comprising 890 aHUS patients, ranging in age from 3 months to 66 years. Common genetic abnormalities included factor H (CFH) mutations, seen in 12% (84/700 patients) across 19 studies, and anti-FH IgG autoantibodies, identified in 27.1% (102/376 patients) from 10 studies. The central nervous system was the most frequently involved extrarenal site [28% (240/858 patients) from 32 studies], with seizures as the predominant CNS symptom. Gastrointestinal symptoms were next most common [31% (230/741 patients) from 25 studies], followed by cardiovascular involvement [16% (97/607) from 23 studies]. Kidney failure was reported in 13.2% (61/463 patients) from 11 studies, with an overall mortality rate of 8.9% (56/632 patients) reported across 27 studies.

CONCLUSIONS

Around 20-30% of aHUS patients experience extrarenal manifestations, with neurologic symptoms occurring most frequently. Due to the high costs and limited availability, genetic data is rarely reported, and studies are often small, underscoring the need for larger, multi-center cohort studies.

PROSPERO REGISTRATION

466915.

IMPACT

Approximately 20-30% of patients with atypical Hemolytic Uremic Syndrome (aHUS) experienced extrarenal manifestations, with neurologic involvement being the most common. Current studies in aHUS patients are heterogeneous and inconsistent in reporting complement mutations with extrarenal manifestations. This systematic review highlights the significance of multi-system assessment in aHUS patients and the need for larger, multi-centered cohort studies.

Adolescence-onset atypical hemolytic uremic syndrome: is it different from infant-onset?

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is a rare, mostly complement-mediated thrombotic microangiopathy. The majority of patients are infants. In contrast to infantile-onset aHUS, the clinical and genetic characteristics of adolescence-onset aHUS have not been sufficiently addressed to date.

METHODS

A total of 28 patients (21 girls, 7 boys) who were diagnosed as aHUS between the ages of ≥10 years and <18 years were included in this study. All available data in the Turkish Pediatric aHUS registry were collected and analyzed.

RESULTS

The mean age at diagnosis was 12.8±2.3 years. Extra-renal involvement was noted in 13 patients (46.4%); neurological involvement was the most common (32%). A total of 21 patients (75%) required kidney replacement therapy. Five patients (17.8%) received only plasma therapy and 23 (82%) of the patients received eculizumab. Hematologic remission and renal remission were achieved in 25 (89.3%) and 17 (60.7%) of the patients, respectively. Compared with the infantile-onset aHUS patients, adolescent patients had a lower complete remission rate during the first episode (p = 0.002). Genetic analyses were performed in all and a genetic variant was detected in 39.3% of the patients. The mean follow-up duration was 4.9±2.6 years. At the last visit, adolescent patients had lower eGFR levels (p = 0.03) and higher rates of chronic kidney disease stage 5 when compared to infantile-onset aHUS patients (p = 0.04).

CONCLUSIONS

Adolescence-onset aHUS is a rare disease but tends to cause more permanent renal dysfunction than infantile-onset aHUS. These results may modify the management approaches in these patients.

Exploring the Intersection of Atypical Hemolytic Uremic Syndrome and Substance Use: A Comprehensive Narrative Review

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by hemolytic anemia, renal failure, and thrombocytopenia. While the typical form of HUS is often associated with Shiga toxin-producing Escherichia coli (STEC) infections, atypical hemolytic uremic syndrome (aHUS) is caused by uncontrolled complement system activation, leading to endothelial damage, microthrombi formation, and other complications. Although aHUS is commonly linked to genetic mutations and infections, emerging evidence suggests that certain substances, particularly illicit drugs like heroin, cocaine, and ecstasy, can also trigger this condition, adding complexity to its diagnosis and management. This narrative review examines the mechanisms by which substance use can lead to aHUS, discusses its clinical presentation, and highlights the diagnostic challenges in distinguishing it from other thrombotic microangiopathies, such as thrombotic thrombocytopenic purpura (TTP) and STEC-HUS. A thorough literature search identified relevant case reports, case series, and observational studies, underscoring the need for genetic testing and complement assays to confirm aHUS in substance users. The review also explores the role of complement inhibitors, such as eculizumab and ravulizumab, which target the underlying pathophysiology and have shown promise in improving patient outcomes. However, the management of substance-induced aHUS remains challenging due to limited data, varying clinical presentations, and the need to optimize treatment protocols. Early recognition and tailored therapy are crucial for effective management. Further research is needed to refine diagnostic criteria, develop new therapeutic approaches, and improve care for patients with this under-recognized condition.

Unprecedented Haemorrhagic Stroke: A Rare Manifestation of Atypical Haemolytic Syndrome

Atypical haemolytic uraemic syndrome (aHUS) is a rare and complex condition characterized by systemic thrombotic microangiopathy resulting from complement dysregulation. While primarily affecting renal microvasculature, aHUS can present with multi-organ involvement, posing significant diagnostic and therapeutic challenges. We report the case of a 22-year-old female with a history of aHUS who developed a catastrophic haemorrhagic stroke. Her clinical course underscores the severe and unpredictable nature of aHUS, illustrating the critical need for heightened awareness of its potential neurological manifestations. aHUS is typically triggered by a combination of genetic predisposition and environmental factors such as infections or medications. This case highlights the necessity for comprehensive evaluation and prompt intervention in patients with aHUS presenting with atypical symptoms. The complexity of aHUS necessitates a multidisciplinary approach to diagnosis and management to mitigate morbidity and mortality.

Living with Atypical Hemolytic Uremic Syndrome in the Netherlands: Patient and Family Perspective

Introduction

Atypical hemolytic uremic syndrome (aHUS) poses a significant health challenge due to its rarity and severity within the spectrum of thrombotic microangiopathy. Despite efforts to optimize and personalize health care for patients with aHUS, understanding the individual experiences, needs, and desires of patients with aHUS and their relatives remains limited.

Methods

Here, we present a nationwide, exploratory, qualitative interview study with a direct content analysis approach. In-depth interviews and a 6-week evaluation were audio-recorded and conducted using a semistructured topic guide, based on the Institute for Positive Health (IPH) model.

Results

Analysis of 10 interviews involving 6 patients with aHUS and 13 relatives revealed the prevalence of long-term disease symptoms in adult patients, notably fatigue, which significantly impacted daily functioning. Moreover, the resilience demonstrated by patients and their relatives was noteworthy; however, the acute phase of aHUS and the unpredictable nature of disease recurrence could profoundly affect mental well-being. The emotional toll of aHUS is pervasive, with feelings of fear, guilt, and trauma persisting across disease phases in both patients and relatives. Challenges in medical care, including delays in diagnosis and the need for personalized and uniform protocols, were highlighted. Support was deemed crucial, indicating the necessity for enhancements in the accessibility to comprehensible disease information and psychological counseling. Finally, complexities surrounding genetic testing and carriership were discussed.

Conclusion

This study underscores the profound, enduring, and multifaced impact of aHUS. The insights gleaned from the experiences and needs of patients with aHUS and their relatives could lay the foundation for development and implementation of more personalized innovations in aHUS health care.

A case-based narrative review of pregnancy-associated atypical hemolytic uremic syndrome/complement-mediated thrombotic microangiopathy

Atypical hemolytic uremic syndrome is a complement-mediated thrombotic microangiopathy caused by uncontrolled activation of the alternative complement pathway in the setting of autoantibodies to or rare pathogenic genetic variants in complement proteins. Pregnancy may serve as a trigger and unmask atypical hemolytic uremic syndrome/complement-mediated thrombotic microangiopathy (aHUS/CM-TMA), which has severe, life-threatening consequences. It can be difficult to diagnose aHUS/CM-TMA in pregnancy due to overlapping clinical features with other thrombotic microangiopathy syndromes including hypertensive disorders of pregnancy. However, the distinction among thrombotic microangiopathy etiologies in pregnancy is important because each syndrome has specific disease management and treatment. In this narrative review, we discuss 2 cases to illustrate the diagnostic challenges and evolving approach in the management of pregnancy-associated aHUS/CM-TMA. The first case involves a 30-year-old woman presenting in the first trimester who was diagnosed with aHUS/CM-TMA and treated with eculizumab from 19 weeks' gestation. Genetic testing revealed a likely pathogenic variant in CFI. She successfully delivered a healthy infant at 30 weeks' gestation. In the second case, a 22-year-old woman developed severe postpartum HELLP syndrome, requiring hemodialysis. Her condition improved with supportive management, yet investigations assessing for aHUS/CM-TMA remained abnormal 6 months postpartum consistent with persistent complement activation but negative genetic testing. Through detailed case discussion describing tests assessing for placental health, fetal anatomy, complement activation, autoantibodies to complement regulatory proteins, and genetic testing for aHUS/CM-TMA, we describe how these results aided in the clinical diagnosis of pregnancy-associated aHUS/CM-TMA and assisted in guiding patient management, including the use of anticomplement therapy.

Modeling complement activation on human glomerular microvascular endothelial cells

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare kidney disease caused by dysregulation of the complement alternative pathway. The complement dysregulation specifically leads to damage to the glomerular endothelium. To further understand aHUS pathophysiology, we validated an ex vivo model for measuring complement deposition on both control and patient human glomerular microvascular endothelial cells (GMVECs).

Methods

Endothelial cells were incubated with human test sera and stained with an anti-C5b-9 antibody to visualize and quantify complement depositions on the cells with immunofluorescence microscopy.

Results

First, we showed that zymosan-activated sera resulted in increased endothelial C5b-9 depositions compared to normal human serum (NHS). The levels of C5b-9 depositions were similar between conditionally immortalized (ci)GMVECs and primary control GMVECs. The protocol with ciGMVECs was further validated and we additionally generated ciGMVECs from an aHUS patient. The increased C5b-9 deposition on control ciGMVECs by zymosan-activated serum could be dose-dependently inhibited by adding the C5 inhibitor eculizumab. Next, sera from five aHUS patients were tested on control ciGMVECs. Sera from acute disease phases of all patients showed increased endothelial C5b-9 deposition levels compared to NHS. The remission samples showed normalized C5b-9 depositions, whether remission was reached with or without complement blockage by eculizumab. We also monitored the glomerular endothelial complement deposition of an aHUS patient with a hybrid complement factor H (CFH)/CFH-related 1 gene during follow-up. This patient had already chronic kidney failure and an ongoing deterioration of kidney function despite absence of markers indicating an aHUS flare. Increased C5b-9 depositions on ciGMVECs were observed in all samples obtained throughout different diseases phases, except for the samples with eculizumab levels above target. We then tested the samples on the patient's own ciGMVECs. The C5b-9 deposition pattern was comparable and these aHUS patient ciGMVECs also responded similar to NHS as control ciGMVECs.

Discussion

In conclusion, we demonstrate a robust and reliable model to adequately measure C5b-9-based complement deposition on human control and patient ciGMVECs. This model can be used to study the pathophysiological mechanisms of aHUS or other diseases associated with endothelial complement activation ex vivo.

Clinical features and management of atypical hemolytic uremic syndrome patient with DGKE gene variants: a case report

Background

Atypical hemolytic uremic syndrome (aHUS) with diacylglycerol kinase epsilon (DGKE) gene variant is a rare variant of thrombotic microangiopathy (TMA). The information on the clinical features, management and long-term outcomes of DGKE-aHUS patients have not yet been fully elucidated. The aim of this study was to report a novel variant of the DGKE gene in a Chinese population with aHUS.

Case presentation

The present work reports a 7-month-old boy with aHUS, possibly triggered by gastrointestinal infection, without complement activation, with little response to plasma therapy and nephroprotective measures. The patient died during the 8th week of his hospital stay. The causes of death were intracranial hemorrhage and multiorgan dysfunction. Comprehensive WES of peripheral blood-derived DNA revealed two heterozygous variations in the DGKE exon region: NM_003647.2, c.610dup, p.Thr204Asnfs*4 and deletion of exons 4-6.

Conclusions

This case suggest that atypical HUS with DGKE gene variant has a poor prognosis with a high mortality rate, which typically manifests in the first year of life and presents as a systemic disease with early-onset HUS with rapidly worsening renal function and chronic proteinuria. There is no specific treatment for DGKE-aHUS. There have an uncertain benefit of plasma therapy for DGKE-aHUS patients. The literature demonstrated that anti-complement therapy showed benefits for DGKE-aHUS with complement activation and autoantibodies during the overt TMA presentation but did not prevent TMA relapses. Early diagnosis and treatment may prevent complications and improve prognosis.

Barriers and facilitators to the implementation of guidelines in rare diseases: a systematic review

BACKGROUND

Rare diseases present a challenge to guideline implementation due to a low prevalence in the general population and the unfamiliarity of healthcare professionals. Existing literature in more common diseases references barriers and facilitators to guideline implementation. This systematic review aims to identify these barriers and facilitators in rare diseases from existing literature.

METHODS

A multi-stage strategy included searching MEDLINE PubMed, EMBASE Ovid, Web of Science and Cochrane library from the earliest date available to April 2021, Orphanet journal hand-search, a pearl-growing strategy from a primary source and reference/citation search was performed. The Integrated Checklist of Determinants of Practice which comprises of twelve checklists and taxonomies, informed by 57 potential determinants was selected as a screening tool to identify determinants that warrant further in-depth investigation to inform design of future implementation strategies.

RESULTS

Forty-four studies were included, most of which were conducted in the United States (54.5%). There were 168 barriers across 36 determinants (37 studies) and 52 facilitators across 22 determinants (22 studies). Fifteen diseases were included across eight WHO ICD-11 disease categories. Together individual health professional factors and guideline factors formed the majority of the reported determinants (59.5% of barriers and 53.8% of facilitators). Overall, the three most reported individual barriers were the awareness/familiarity with the recommendation, domain knowledge and feasibility. The three most reported individual facilitators were awareness/familiarity with the recommendation, agreement with the recommendation and ability to readily access the guidelines. Resource barriers to implementation included technology costs, ancillary staff costs and more cost-effective alternatives. There was a paucity of studies reporting influential people, patient advocacy groups or opinion leaders, or organisational factors influencing implementation.

CONCLUSIONS

Key barriers and facilitators to the implementation of clinical practice guidelines in the setting of rare diseases were at the individual health professional and guideline level. Influential people and organisational factors were relatively under-reported and warrant exploration, as does increasing the ability to access the guidelines as a potential intervention.

Atypical hemolytic uremic syndrome: Consensus of diagnosis and treatment in Taiwan

Atypical hemolytic uremic syndrome (aHUS), characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, is a rare but life-threatening systemic disorder caused by the dysregulation of the complement pathway. Current advances in molecular analysis and pathogenesis have facilitated the establishment of diagnosis and development of effective complement blockade. Based on this recent consensus, we provide suggestions regarding the diagnosis and management of aHUS in Taiwan. The diagnosis of aHUS is made by the presence of TMA with normal ADAMTS13 activity without known secondary causes. Although only 60% of patients with aHUS have mutations in genes involving the compliment and coagulation systems, molecular analysis is suggestive for helping establish diagnosis, clarifying the underlying pathophysiology, guiding the treatment decision-making, predicting the prognosis, and deciding renal transplantation. Complement blockade, anti-C5 monoclonal antibody, is the first-line therapy for patients with aHUS. Plasma therapy should be considered for removing autoantibody in patients with atypical HUS caused by anti-CFH or complement inhibitor is unavailable.

Comparison of outcomes after plasma therapy or eculizumab in pediatric patients with atypical hemolytic uremic syndrome

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is an ultra-rare and life-threatening disease. For decades, plasma therapy was used to manage patients with aHUS. Since eculizumab, a recombinant humanized anti-C5 monoclonal antibody, was approved for treatment of aHUS, it has been used to treat patients with aHUS. Here, we examined the effectiveness of eculizumab and plasma therapy, respectively in the treatment of pediatric patients with aHUS.

METHODS

Data were collected from questionnaires sent to 75 institutions known to be treating thrombotic microangiopathy (TMA).

RESULTS

A total of 24 patients were evaluable, in which no recurrence of TMA was reported at last observation. There were four therapy groups: two patients receiving supportive therapy, one receiving plasma therapy alone, 17 switching from plasma therapy to eculizumab (therapy switched), and four receiving eculizumab alone. Among 17 patients of therapy-switched group, only one patient achieved complete remission at the end of plasma therapy, 15 patients achieved complete remission after eculizumab initiation, and two patients reached end-stage renal disease. Adverse events were reported in nine cases; among these, meningococcal infection, anaphylaxis, and eculizumab-related infusion reaction were reported among those treated with eculizumab.

CONCLUSION

This study provided substantial evidence from a Japanese population that the conversion from plasma therapy to eculizumab therapy should be considered in patients with aHUS who show an incomplete response to plasma therapy. In addition, although no new safety events were detected, careful attention should be paid to meningococcal infection, eculizumab-related infusion reactions and allergic reactions with administration of eculizumab.

Pharmacological Management of Atypical Hemolytic Uremic Syndrome in Pediatric Patients: Current and Future

Atypical hemolytic uremic syndrome is a thrombotic microangiopathy characterized by hemolysis, thrombocytopenia, and acute kidney injury, usually caused by alternative complement system overactivation due to pathogenic genetic variants or antibodies to components or regulatory factors in this pathway. Previously, a lack of effective treatment for this condition was associated with mortality, end-stage kidney disease, and the risk of disease recurrence after kidney transplantation. Plasma therapy has been used for atypical hemolytic uremic syndrome treatment with inconsistent results. Complement-blocking treatment changed the outcome and prognosis of patients with atypical hemolytic uremic syndrome. Early administration of eculizumab, a monoclonal C5 antibody, leads to improvements in hematologic, kidney, and systemic manifestations in patients with atypical hemolytic uremic syndrome, even with apparent dialysis dependency. Pre- and post-transplant use of eculizumab is effective in the prevention of atypical hemolytic uremic syndrome recurrence. Evidence on eculizumab use in secondary hemolytic uremic syndrome cases is controversial. Recent data favor the restrictive use of eculizumab in carefully selected atypical hemolytic uremic syndrome cases, but close monitoring for relapse after drug discontinuation is emphasized. Prophylaxis for meningococcal infection is important. The long-acting C5 monoclonal antibody ravulizumab is now approved for atypical hemolytic uremic syndrome treatment, enabling a reduction in the dosing frequency and improving the quality of life in patients with atypical hemolytic uremic syndrome. New strategies for additional and novel complement blockage medications in atypical hemolytic uremic syndrome are under investigation.

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.

Early Eculizumab Withdrawal in Patients With Atypical Hemolytic Uremic Syndrome in Native Kidneys Is Safe and Cost-Effective: Results of the CUREiHUS Study

Introduction

The introduction of eculizumab has improved the outcome in patients with atypical hemolytic uremic syndrome (aHUS). The optimal treatment strategy is debated. Here, we report the results of the CUREiHUS study, a 4-year prospective, observational study monitoring unbiased eculizumab discontinuation in Dutch patients with aHUS after 3 months of therapy.

Methods

All pediatric and adult patients with aHUS in native kidneys and a first-time eculizumab treatment were evaluated. In addition, an extensive cost-consequence analysis was conducted.

Results

A total of 21 patients were included in the study from January 2016 to October 2020. In 17 patients (81%), a complement genetic variant or antibodies against factor H were identified. All patients showed full recovery of hematological thrombotic microangiopathy (TMA) parameters after the start of eculizumab. A renal response was noted in 18 patients. After a median treatment duration of 13.6 weeks (range 2.1-43.9), eculizumab was withdrawn in all patients. During follow-up (80.7 weeks [0.0-236.9]), relapses occurred in 4 patients. Median time to first relapse was 19.5 (14.3-53.6) weeks. Eculizumab was reinitiated within 24 hours in all relapsing patients. At last follow-up, there were no chronic sequelae, i.e., no clinically relevant increase in serum creatinine (sCr), proteinuria, and/or hypertension in relapsing patients. The low sample size and event rate did not allow to determine predictors of relapse. However, relapses only occurred in patients with a likely pathogenic variant. The cost-effectiveness analysis revealed that the total medical expenses of our population were only 30% of the fictive expenses that would have been made when patients received eculizumab every fortnight.

Conclusion

It is safe and cost-effective to discontinue eculizumab after 3 months of therapy in patients with aHUS in native kidneys. Larger data registries are needed to determine factors associated with suboptimal kidney function recovery during eculizumab treatment, factors to predict relapses, and long-term outcomes of eculizumab discontinuation.

Safety and impact of eculizumab withdrawal in patients with atypical haemolytic uraemic syndrome: protocol for a multicentre, open-label, prospective, single-arm study

INTRODUCTION

Atypical haemolytic uraemic syndrome (aHUS) is a rare, life-threatening disease caused by excessive activation of part of the immune system called complement. Eculizumab is an effective treatment, controlling aHUS in 90% of patients. Due to the risk of relapse, lifelong treatment is currently recommended. Eculizumab treatment is not without problems, foremost being the risk of severe meningococcal infection, the burden of biweekly intravenous injections and the high cost.This paper describes the design of the Stopping Eculizumab Treatment Safely in aHUS trial that aims to establish whether a safety monitoring protocol, including the reintroduction of eculizumab for those who relapse, could be a safe, alternative treatment strategy for patients with aHUS.

METHODS AND ANALYSIS

This is a multicentre, non-randomised, open-label study of eculizumab withdrawal with continuous monitoring of thrombotic microangiopathy-related serious adverse events using the Bayes factor single-arm design. 30 patients will be recruited to withdraw from eculizumab and have regular blood and urine tests for 24 months, to monitor for disease activity. If relapse occurs, treatment will be restarted within 24 hours of presentation. 20 patients will remain on treatment and complete health economic questionnaires only. An embedded qualitative study will explore the views of participants.

ETHICS AND DISSEMINATION

A favourable ethical opinion and approval was obtained from the North East-Tyne & Wear South Research Ethics Committee. Outcomes will be disseminated via peer-reviewed articles and conference presentations.

TRIAL REGISTRATION NUMBER

EudraCT number: 2017-003916-37 and ISRCTN number: ISRCTN17503205.

Systematic review of atypical hemolytic uremic syndrome biomarkers

BACKGROUND AND OBJECTIVES

Observing biomarkers that affect alternative pathway dysregulation components may be effective in obtaining a new and more rapid diagnostic portrayal of atypical hemolytic uremic syndrome. We have conducted a systematic review on the aHUS biomarkers: C3, C5a, C5b-9, factor B, complement factor B, H, and I, CH50, AH50, D-dimer, as well as anti-CFH antibodies.

METHODS

An exhaustive literature search was conducted for aHUS patient population plasma/serum, collected/reported at the onset of diagnosis. A total of 60 studies were included with the data on 837 aHUS subjects, with at least one biomarker reported.

RESULTS

The biomarkers C3 [mean (SD): 72.1 (35.0), median: 70.5 vs. reference range: 75-175 mg/dl, n = 752]; CH50 [28.3 (32.1), 24.3 vs. 30-75 U/ml, n = 63]; AH50 [27.6% (30.2%), 10% vs. ≥ 46%, n = 23]; and CFB [13.1 (6.6), 12.4, vs. 15.2-42.3 mg/dl, n = 19] were lower among aHUS subjects as compared with the reference range. The biomarkers including C4 [mean (SD): 20.4 (9.5), median: 20.5 vs. reference range: 14-40 mg/dl, n = 343]; C4d [7.2 (6.5), 4.8 vs. ≤ 9.8 μg/ml, n = 108]; CFH [40.2 (132.3), 24.5 vs. 23.6-43.1 mg/dl, n = 123 subjects]; and CFI [8.05 (5.01), 6.55 mg/dl vs. 4.4-18.1 mg/dl, n = 38] were all observed to be within the reference range among aHUS subjects. The biomarkers C5a [mean (SD): 54.9 (32.9), median: 48.8 vs. reference range: 10.6-26.3 mg/dl, n = 117]; C5b-9 [466.0 (401.4), 317 (186-569.7) vs. ≤ 250 ng/ml, n = 174]; Bb [2.6 (2.1), 1.9 vs. ≤ 1.6 μg/ml, n = 77] and D-dimer [246 (65.05), 246 vs. < 2.2 ng/ml, 2, n = 2 subjects] were higher among patients with aHUS compared with the reference range.

CONCLUSION

If a comprehensive complement profile were built using our data, aHUS would be identified by low levels of C3, CH50, AH50, and CFB along with increased levels of C5a, C5b-9, Bb, anti-CFH autoantibodies, and D-dimer. A higher resolution version of the Graphical abstract is available as Supplementary information.

Paediatric nephrology in under-resourced areas

BACKGROUND

Nearly 50% of the world population and 60% of children aged 0 to 14 years live in low- or lower-middle-income countries. Paediatric nephrology (PN) in these countries is not a priority for allocation of limited health resources. This article explores advancements made and persisting limitations in providing optimal PN services to children in such under-resourced areas (URA).

METHODS

Medline, PubMed and Google Scholar online databases were searched for articles pertaining to PN disease epidemiology, outcome, availability of services and infrastructure in URA. The ISN and IPNA offices were contacted for data, and two online questionnaire surveys of IPNA membership performed. Regional IPNA members were contacted for further detailed information.

RESULTS

There is a scarcity of published data from URA; where available, prevalence of PN diseases, managements and outcomes are often reported to be different from high income regions. Deficiencies in human resources, fluoroscopy, nuclear imaging, immunofluorescence, electron microscopy and genetic studies were identified. Several drugs and maintenance kidney replacement therapy are inaccessible to the majority of patients. Despite these issues, regional efforts with support from international bodies have led to significant advances in PN services and infrastructure in many URA.

CONCLUSIONS

Equitable distribution and affordability of PN services remain major challenges in URA. The drive towards acquisition of regional data, advocacy to local government and non-government agencies and partnership with international support bodies needs to be continued. The aim is to optimise and achieve global parity in PN training, investigations and treatments, initially focusing on preventable and reversible conditions.

Pediatric Atypical Hemolytic Uremic Syndrome Advances

Atypical hemolytic uremic syndrome (aHUS) is a rare disorder characterized by dysregulation of the alternate pathway. The diagnosis of aHUS is one of exclusion, which complicates its early detection and corresponding intervention to mitigate its high rate of mortality and associated morbidity. Heterozygous mutations in complement regulatory proteins linked to aHUS are not always phenotypically active, and may require a particular trigger for the disease to manifest. This list of triggers continues to expand as more data is aggregated, particularly centered around COVID-19 and pediatric vaccinations. Novel genetic mutations continue to be identified though advancements in technology as well as greater access to cohorts of interest, as in diacylglycerol kinase epsilon (DGKE). DGKE mutations associated with aHUS are the first non-complement regulatory proteins associated with the disease, drastically changing the established framework. Additional markers that are less understood, but continue to be acknowledged, include the unique autoantibodies to complement factor H and complement factor I which are pathogenic drivers in aHUS. Interventional therapeutics have undergone the most advancements, as pharmacokinetic and pharmacodynamic properties are modified as needed in addition to their as biosimilar counterparts. As data continues to be gathered in this field, future advancements will optimally decrease the mortality and morbidity of this disease in children.

Blockade of the Terminal Complement Cascade Using Ravulizumab in a Pediatric Patient With Anti-complement Factor H Autoantibody-Associated aHUS: A Case Report and Literature Review

Atypical hemolytic uremic syndrome (aHUS) is a rare disease in pediatrics with 6-10% of cases associated with complement factor H autoantibodies. Ravulizumab is a new treatment option available for long-term management through blockage of the terminal complement cascade. We report a case of a previously healthy eight-year-old female who presented with hemolytic anemia, thrombocytopenia, and acute kidney injury. Low complement C3, normal ADAMTS13, and negative rheumatology and infectious disease panels suggested aHUS. A follow-up complement aHUS/TMA gene panel was negative for ADAMTS13, C3, CD46, CFB, CFD, CFH, CFHR1, CFHR3, CFHR5, CRI, DGKE, PLG, and THBD mutations and positive for MCP/CD46 haplotype and CFH-H3 haplotype. Further testing found decreased factor H (B1H) plasma level and increased factor H autoantibody, suggesting anti-factor H antibody-associated aHUS. She received hemodialysis (2 treatments) and eculizumab was initiated promptly. The patient had complete renal recovery after one month of therapy, and anemia, thrombocytopenia, and hemolysis resolved after two months of therapy. After five months of therapy, eculizumab was successfully switched to ravulizumab. After 12 months of initial diagnosis, complement C3 and factor H normalized, however, factor H autoantibody remained elevated. The case supports the notion that timely recognition of anti-FH-associated aHUS is important for disease management and that early specific therapy with immunosuppression results in favorable outcomes. It also illustrates that the blockade of the terminal complement cascade using eculizumab holds promise for pediatric cases. Finally, eculizumab can be safely switched to ravulizumab with an optimal longer duration between treatments in the context of aHUS.

Early relapse of atypical hemolytic uremic syndrome following ABO-incompatible living-related pediatric kidney re-transplant successfully treated with eculizumab

BACKGROUND

A 3-year-old girl with clinical features of atypical HUS (complement Factor I mutation inherited from an asymptomatic mother and Factor H autoantibodies) was treated with plasma exchange, progressed to kidney failure (KF) aged 4 years, and received an en bloc kidney DCD transplant aged 8 years with primary graft non-function necessitating transplant nephrectomy at the time of transplantation. She subsequently underwent re-transplantation from her father. This is a retrospective study of electronic patient records and medical notes.

CASE-DIAGNOSIS/TREATMENT

A 9-year-old girl received an ABO-incompatible (ABOi) living-related kidney transplant from her father with recipient and donor blood groups of O and A, respectively, with baseline recipient anti-A titers 1:128 reducing to 1:4 at the time of transplant with B lymphocyte depletion with rituximab and four sessions of immunoadsorption. Six hours post-transplant, she had recurrence of aHUS and received the first dose of eculizumab. She continues on monthly home eculizumab infusions with stable kidney allograft function and negative anti-A titers 7 years post-kidney transplantation.

CONCLUSIONS

This is the first report of a pediatric high-risk ABOi living-related kidney transplantation in whom early relapse of aHUS was successfully treated with eculizumab with good long-term patient and allograft outcome.

Influenza-associated hemolytic uremic syndrome: The pathogenic role of the virus

A 3-year-old girl came to our attention for fever and upper respiratory tract infection associated with thrombocytopenia, non-immune hemolytic anemia, and acute kidney injury (AKI). Complete blood count and renal function slowly normalized, with no need for dialysis. She was always normotensive with valid diuresis; her neurological status also rapidly improved. Nasal swab turned out positive for influenza A H1N1; stool test was negative for Shiga toxin-producing Escherichia coli (STEC). The patient was treated with oseltamivir for 5 days with a favorable outcome. Association between hemolytic uremic syndrome (HUS) and H1N1 influenza is poorly reported in literature [1, 2, 3, 4]. The pathogenic role of the virus in causing HUS is still controversial and debated [1, 2, 3, 4]. In our patient, complement activity markers (serum C3 and C5b-9) alteration suggested a transient, virus-mediated complement activation.

Severe Acute Neurologic Involvement in Children With Hemolytic-Uremic Syndrome

BACKGROUND AND OBJECTIVES

Acute severe neurologic involvement is the most threatening complication in children with hemolytic-uremic syndrome (HUS). Our primary study objectives were to describe the association between acute neurologic manifestations (ANMs) and in-hospital mortality among children with HUS.

METHODS

Using the Pediatric Health Information System database, in this retrospective multicenter cohort study, we identified the first HUS-related inpatient visit among children ≤18 years (years 2004-2018). Frequency of selected ANMs and combinations of ANMs, as well as the rate of mortality, was calculated. Multivariate logistic regression was used to identify the association of ANMs and the risk of in-hospital mortality.

RESULTS

Among 3915 patients included in the analysis, an ANM was noted in 10.4% (n = 409) patients. Encephalopathy was the most common ANM (n = 245). Mortality was significantly higher among patients with an ANM compared with patients without an ANM (13.9% vs 1.8%; P < .001). Individuals with any ANM had increased odds of mortality (odds ratio [OR]: 2.25; 95% confidence interval [CI]: 1.29-3.93; P = .004), with greater risk (OR: 2.60; 95% CI: 1.34-5.06; P = .005) among patients with ≥2 manifestations. Brain hemorrhage (OR: 3.09; 95% CI: 1.40-6.82; P = .005), brain infarction (OR: 2.64; 95% CI: 1.10-6.34; P = .03), anoxic brain injury (OR: 3.92; 95% CI: 1.49-10.31; P = .006), and brain edema (OR: 4.81; 95% CI: 1.82-12.71; P = .002) were independently associated with mortality.

CONCLUSIONS

In this study, the largest systematic assessment of ANMs among children with HUS to date, we identify differences in in-hospital mortality based on the type of ANM, with increased risk observed for patients with multiple ANMs.

Case Report: Variable Pharmacokinetic Profile of Eculizumab in an aHUS Patient

Background

With the introduction of eculizumab, a C5-inhibitor, morbidity and mortality improved significantly for patients with atypical hemolytic uremic syndrome (aHUS). In view of the high costs, actual needs of the drug, and increasing evidence in literature, aHUS patients can be treated according to a restrictive eculizumab regimen. We retrospectively analyzed the pharmacokinetic and dynamic parameters of eculizumab in one patient in time, emphasizing various factors which could be taken into account during tapering of treatment.

Case Presentation

A nowadays 18-year-old male with a severe, frequently relapsing form of atypical HUS due to a hybrid CFH/CFHR1 gene in combination with the homozygous factor H haplotype, required chronic plasma therapy (PT), including periods with plasma infusion, from the age of onset at 5 months until initiation of eculizumab at the age of 11 years. A mild but stable chronic kidney disease (CKD) and 9 years of disease remission enabled prolongation of eculizumab interval. At the age of 15 years, a sudden yet multifactorial progression of chronic kidney disease (CKD) was observed, without any signs of disease recurrence. However, an acquired glomerulocystic disease, a reduced left kidney function, and abnormal abdominal venous system of unknown etiology were found. In addition, after an aHUS relapse, an unexpected increase in intra-patient variability of eculizumab concentrations was seen. Retrospective pharmacokinetic analysis revealed a change in eculizumab clearance, associated with a simultaneous increase in proteinuria.

Conclusion

High intra-patient variability of eculizumab pharmacokinetics were observed over time, emphasizing the necessity for adequate and continuous therapeutic drug monitoring in aHUS patients. Eculizumab serum trough levels together with complement activation markers (CH50) should be frequently assessed, especially during tapering of drug therapy and/or changing clinical conditions in the patient. In addition, an increase in proteinuria could result in urinary eculizumab loss, indicating that urinary monitoring of eculizumab may be important in aHUS patients with an unexplained decline in serum concentrations.

Molecular basis and outcomes of atypical haemolytic uraemic syndrome in Czech children

Atypical haemolytic uraemic syndrome is an ultra-rare, life-threatening disease. Causative variants in genes that encode complement factors can be identified in 40-70% of cases. We performed genetic analysis of 21 Czech children with atypical haemolytic uraemic syndrome. Genetic or acquired predisposition to the disease was identified in the majority of our patients: CFHR1 and CFHR3 deletions in 14/21 (67%; 13 of them were positive for anti-complement factor H antibodies), variants in complement genes or DGKE in 13/21 (62%). Multiple genetic findings were identified in eight patients (38%). The incidence of atypical haemolytic uraemic syndrome in the Czech paediatric population was estimated to be 0.092 (CI 0.053-0.131) cases per million inhabitants and 0.92 (CI 0.53-1.32) cases per 100,000 births for the entire reporting period. Ten patients were initially treated with plasma exchange and eight with eculizumab or with a combination of eculizumab and plasma exchange. At the last follow-up, 20 patients were alive and one patient had end-stage renal disease.Conclusion: The incidence of atypical haemolytic uraemic syndrome in the Czech paediatric population corresponds to the reported incidence in Europe. We detected the unusually high rate of CFHR1/CFHR3 deletions associated with anti-complement factor H antibodies in Czech paediatric patients. Treatment by eculizumab led to superior outcomes and prevention of the disease relapses compared with plasma exchange therapy. Our results may help to understand the polygenic nature of atypical haemolytic uraemic syndrome as a disease that results from a combination of various risk factors. What is Known: • Atypical haemolytic uraemic syndrome (aHUS) is considered a polygenic and multifactorial disease. Genetic predisposition to aHUS is identified in 40-70% of children. • Anti-complement factor H antibodies are usually found in 6-25% of affected children. What is New: • Potentially causative genetic or acquired factors were confirmed in the majority of patients. The prevailing finding was the unusually high rate of CFHR1/CFHR3 deletions associated with anti-complement factor H antibodies (62% of patients). • The incidence of aHUS in Czech children is 0.092 (CI 0.053-0.131) cases per million inhabitants and 0.92 (CI 0.53-1.32) cases per 100,000 births for the entire reporting period.

Atypical hemolytic and uremic syndrome due to C3 mutation in pancreatic islet transplantation: a case report

Background

We here report on the first observation of a C3 mutation that is related to atypical hemolytic and uremic syndrome (aHUS), which occurred in a pancreatic islet transplant patient. Immunosuppressive treatments, such as calcineurin inhibitors, have been linked to undesirable effects like nephrotoxicity.

Case presentation

A 40-year-old man with brittle diabetes, who was included in the TRIMECO trial, became insulin-independent 2 months after pancreatic islet transplantation. About 15 months after islet transplantation, the patient exhibited acute kidney injury due to aHUS. Despite plasma exchange and eculizumab treatment, the patient developed end-stage renal disease.

A genetic workup identified a missense variant (p.R592Q) in the C3 gene. In vitro, this C3 variant had defective Factor I proteolytic activity with membrane proteins as cofactor proteins, which was thus classified as pathogenic. About 1 year after the aHUS episode, kidney transplantation was carried out under the protection of the specific anti-C5 monoclonal antibody eculizumab. The patient had normal kidney function, with preserved pancreatic islet function 4 years later.

Conclusions

Pancreatic islet transplantation could have triggered this aHUS episode, but this link needs to be clarified. Although prophylactic eculizumab maintains kidney allograft function, its efficacy still needs to be studied in larger populations.

Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill

Hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and hemolytic uremic syndrome have a similar clinical presentation. Diagnostic needs to be prompt to decrease mortality, because identifying the different disorders can help to tailor specific, effective therapies. However, diagnosis is challenging and morbidity and mortality remain high, especially in the critically ill population. Development of clinical prediction scores and rapid diagnostic tests for hemolytic uremic syndrome based on mechanistic knowledge are needed to facilitate early diagnosis and assign timely specific treatments to patients with hemolytic uremic syndrome variants.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

Eculizumab in paediatric atypical haemolytic uraemic syndrome: Lessons learned from a single-centre experience in the United Arab Emirates

AIM

Atypical haemolytic uraemic syndrome (aHUS) is a debilitating condition that can cause significant morbidity and mortality in children if not adequately and promptly treated. This report shares real-world data on the use of eculizumab in children with aHUS.

METHODS

We report our experience with the use of eculizumab in 14 children with aHUS.

RESULTS

The median age at aHUS diagnosis was 12 months (range: 2-108 months), with six (42.9%) patients presenting in infancy and six (42.9%) being males. Eculizumab therapy was associated with haematological and thrombotic microangiopathy responses in 14 (100%) and 13 (92.9%) patients after a median of 9 days (range: 7-12 days) and 9.5 days (range: 7-14 days), respectively. None of the six patients who were previously treated with plasma therapy required any further infusions. Of the six patients who previously required dialysis, only one patient continued to do so and eventually received a renal transplant. The median time to ≥25% decrease in serum creatinine level in the remaining patients was 16 days (range: 14-21 days), and estimated glomerular filtration rate increased from a median of 17-101 mL/min/1.73 m² . The safety profile was similar to that reported in the literature, and 10 patients continue to receive therapy, with 3 being on the drug for 4 or more years.

CONCLUSION

Our study adds to the growing body of evidence highlighting the efficacy and safety of eculizumab for the management of children with aHUS.

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.

Extra-renal manifestations of atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a rare and complex disease resulting from abnormal alternative complement activation with a wide range of clinical presentations. Extra-renal manifestations of aHUS can involve many organ systems, including the peripheral and central nervous, gastrointestinal, cardiovascular, integumentary, pulmonary, as well as the eye. While some of these extra-renal manifestations occur in the acute phase of aHUS, some can also occur as long-term sequelae of unopposed complement activation. Extra-renal symptoms are observed in approximately 20% of patients with aHUS, with the incidence of specific organ system complications ranging from a few case reports to 50% of described patients. Careful monitoring for extra-renal involvement is critical in patients with aHUS, as prompt evaluation and management may decrease the risk of high morbidity and mortality associated with aHUS.

Hemolytic uremic syndrome in a developing country: Consensus guidelines

BACKGROUND

Hemolytic uremic syndrome (HUS) is a leading cause of acute kidney injury in children. Although international guidelines emphasize comprehensive evaluation and treatment with eculizumab, access to diagnostic and therapeutic facilities is limited in most developing countries. The burden of Shiga toxin-associated HUS in India is unclear; school-going children show high prevalence of anti-factor H (FH) antibodies. The aim of the consensus meeting was to formulate guidelines for the diagnosis and management of HUS in children, specific to the needs of the country.

METHODS

Four workgroups performed literature review and graded research studies addressing (i) investigations, biopsy, genetics, and differential diagnosis; (ii) Shiga toxin, pneumococcal, and infection-associated HUS; (iii) atypical HUS; and (iv) complement blockade. Consensus statements developed by the workgroups were discussed during a consensus meeting in March 2017.

RESULTS

An algorithm for classification and evaluation was developed. The management of Shiga toxin-associated HUS is supportive; prompt plasma exchanges (PEX) is the chief therapy in patients with atypical HUS. Experts recommend that patients with anti-FH-associated HUS be managed with a combination of PEX and immunosuppressive medications. Indications for eculizumab include incomplete remission with plasma therapy, life-threatening features, complications of PEX or vascular access, inherited defects in complement regulation, and recurrence of HUS in allografts. Priorities for capacity building in regional and national laboratories are highlighted.

CONCLUSIONS

Limited diagnostic capabilities and lack of access to eculizumab prevent the implementation of international guidelines for HUS in most developing countries. We propose practice guidelines for India, which will perhaps be applicable to other developing countries.

Membrane-filtration based plasma exchanges for atypical hemolytic uremic syndrome: Audit of efficacy and safety

BACKGROUND

While complement blockade with eculizumab is recommended as first-line therapy of atypical hemolytic uremic syndrome (aHUS), plasma exchanges (PEX) remain the chief option for anti-factor H (FH) antibody associated disease and when access to eculizumab is limited.

METHODS

We reviewed adverse events (AEs) and adverse outcomes (eGFR <30 mL/min/1.73 m² or death), in all patients with aHUS managed with membrane-filtration based PEX at one tertiary care center over 5.5 years.

RESULTS

During January 2013 to June 2018, 109 patients with aHUS (74 with antibodies to FH), aged median (range) 7.6 (0.5-18) year weighing 22.1 (6-90) kg, underwent 2024 sessions of PEX. AE, in 12.1% patients, were usually self-limiting and included chills (5.5%), vomiting/abdominal pain (3.3%), hypotension (1.6%), urticaria (1.5%), seizures (0.2%), hypocalcemia (0.2%), and hemorrhage (0.1%); plasma hypersensitivity and severe reactions were rare. Rate of catheter-related infections was 1.45/1000 catheter-days. Filter reuse (OR 1.69; 95% CI 1.26-2.26; P < .001) and >20 sessions of PEX/patient (OR 1.99; 95% CI 1.27-3.10; P = .002) were independently associated with adverse events; infusion of IV calcium gluconate during PEX was protective (OR 0.26; 95% CI 0.16-0.43; P < .001). Hematological remission was achieved in 96.3% patients after 6 (5-8) PEX sessions; 80.8% and 89.6% patients were dialysis independent by one and 3 months, respectively.

CONCLUSIONS

PEX is safe and associated with satisfactory short-term outcomes in children with aHUS. Prolonged PEX and filter-reuse are associated with complications.

Clinical and Immunological Profile of Anti-factor H Antibody Associated Atypical Hemolytic Uremic Syndrome: A Nationwide Database

Background: Atypical hemolytic uremic syndrome (aHUS), an important cause of acute kidney injury (AKI), is characterized by dysregulation of the alternative complement pathway. Autoantibodies to factor H (FH), a chief regulator of this pathway, account for a distinct subgroup. While high anti-FH titers predict relapse, they do not correlate well with disease activity and their functional characterization is required.

Methods: Of 781 patients <18-year-old of aHUS in the nationwide database from 2007 to 2018, 436 (55.8%) had anti-FH antibodies. Clinical features and outcome of patients managed in the last 6-year (n = 317) were compared to before (n = 119). In plasma samples of 44 patients, levels of serial circulating FH immune complexes (CIC), free FH, soluble terminal complement complex (sC5b-9), sheep red blood cell (SRBC) lysis and epitope specificity (n = 8) were examined. Functional renal reserve, ambulatory hypertension, left ventricular hypertrophy (LVH), and proteinuria were evaluated in a subset.

Results: Patients presented with markedly elevated anti-FH titers (10,633.2 ± 998.5 AU/ml). Management varied by center, comprising plasma exchange (PEX; 77.5%) and immunosuppression (73.9%). Patients managed in the last 6-year showed better renal survival at mean 28.5 ± 27.3 months (log rank P = 0.022). Mean anti-FH titers stayed 700–1,164 AU/ml during prolonged follow-up, correlating with CIC. Patients with relapse had lower free-FH during remission [Generalized estimating equations (GEE), P = 0.001]; anti-FH levels ≥1,330 AU/ml and free FH ≤440 mg/l predicted relapse (hazards ratio, HR 6.3; P = 0.018). Epitope specificity was similar during onset, remission and relapse. Antibody titer ≥8,000 AU/ml (HR 2.23; P = 0.024), time to PEX ≥14 days (HR 2.09; P = 0.071) and PEX for <14 days (HR 2.60; P = 0.017) predicted adverse renal outcomes. Combined PEX and immunosuppression improved long-term outcomes (HR 0.37; P = 0.026); maintenance therapy reduced risk of relapses (HR 0.11; P < 0.001). At 4.4±2.5 year, median renal reserve was 15.9%; severe ambulatory, masked and pre-hypertension were found in 38, 30, and 18%, respectively. Proteinuria and LVH occurred in 58 and 28% patients, respectively.

Conclusion: Prompt recognition and therapy with PEX and immunosuppression, is associated with satisfactory outcomes. Free-FH predicts early relapses in patients with high anti-FH titers. A significant proportion of impaired functional reserve, ambulatory hypertension, proteinuria and LVH highlight the need for vigilant long-term follow-up.

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.

Atypical Hemolytic-Uremic Syndrome: An Update on Pathophysiology, Diagnosis, and Treatment

Atypical hemolytic uremic syndrome (aHUS), a rare variant of thrombotic microangiopathy, is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. The condition is associated with poor clinical outcomes with high morbidity and mortality. Atypical HUS predominantly affects the kidneys but has the potential to cause multi-organ system dysfunction. This uncommon disorder is caused by a genetic abnormality in the complement alternative pathway resulting in over-activation of the complement system and formation of microvascular thrombi. Abnormalities of the complement pathway may be in the form of mutations in key complement genes or autoantibodies against specific complement factors. We discuss the pathophysiology, clinical manifestations, diagnosis, complications, and management of aHUS. We also review the efficacy and safety of the novel therapeutic agent, eculizumab, in aHUS, pregnancy-associated aHUS, and aHUS in renal transplant patients.

Recurrent Atypical Hemolytic Uremic Syndrome in Children With Acute Lymphoblastic Leukemia Undergoing Maintenance Chemotherapy

Chemotherapy-associated myelosuppression and renal dysfunction is not uncommon during childhood acute lymphoblastic leukemia (ALL) therapy. Here we report 2 cases of atypical hemolytic uremic syndrome (aHUS) presenting with pancytopenia and renal dysfunction that developed during maintenance chemotherapy characterized by hypocomplementemia. Both cases experienced recurrence after resolution of the initial aHUS episode upon resumption of chemotherapy, raising a possible contributory role for chemotherapy in the disease pathogenesis.

Extra-Renal manifestations of atypical hemolytic uremic syndrome in children

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is a chronic disease characterized by thrombotic microangiopathy and a high risk of end-stage kidney disease. Dysregulation and/or excessive activation of the complement system results in thrombotic microangiopathy. Interest in extrarenal manifestations of aHUS is increasing. This study aimed to determine the clinical characteristics of patients with extrarenal manifestations of aHUS in childhood.

METHODS

This study included 70 children with extrarenal manifestations of HUS from the national Turkish aHUS Registry. The demographics, clinical characteristics, genetic test results, all treatments, and renal/hematologic status of aHUS patients with extrarenal involvement were recorded.

RESULTS

The most common extrarenal manifestation was neurological system involvement (n = 46 [27.2%]), followed by gastrointestinal (n = 20 [11.8%]), cardiovascular (n = 12 [7%]), and respiratory (n = 12 [7%]) involvement. The patients with neurological involvement had a higher mortality rate and a lower estimated glomerular filtration rate (eGFR) than the other patients at last follow-up. Eculizumab (with or without plasma exchange/plasma infusion) treatment increased the renal and hematologic recovery rates.

CONCLUSIONS

The most common and serious extrarenal manifestation of aHUS is neurological involvement and treatment outcome findings presented herein are important to all relevant clinicians.

Atypical hemolytic uremic syndrome and eculizumab therapy in children

Hemolytic uremic syndrome (HUS) is often encountered in children with acute kidney injury. Besides the well-known shiga toxin-producing Escherichia coli-associated HUS, atypical HUS (aHUS) caused by genetic complement dysregulation has been studied recently. aHUS is a rare, chronic, and devastating disorder that progressively damages systemic organs, resulting in stroke, end-stage renal disease, and death. The traditional treatment for aHUS is mainly plasmapheresis or plasma infusion; however, many children with aHUS will progress to chronic kidney disease despite plasma therapy. Eculizumab is a newly developed biologic that blocks the terminal complement pathway and has been successfully used in the treatment of aHUS. Currently, several guidelines for aHUS, including the Korean guideline, recommend eculizumab as the first-line therapy in children with aHUS. Moreover, life-long eculizumab therapy is generally recommended. Further studies on discontinuation of eculizumab are needed.

Eculizumab Dosing in Infants

Eculizumab is the therapy of choice for patients with atypical hemolytic uremic syndrome (aHUS). Dosing recommendations stem from two trials: one retrospective trial (19 children and 5 infants) and one prospective trial (22 patients and 5 infants). This case report highlights the need for more precise dosing recommendations in children, particularly in infants, and for smaller vials of the medication to facilitate more precise dosing. Such changes would ensure that adverse events are minimized and that the children with aHUS who are treated with eculizumab experience an optimal clinical response.

Kidney Transplantation in Patients with Atypical Hemolytic Uremic Syndrome due to Complement Factor H Deficiency: Impact of Liver Transplantation

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is a rare disease that is often associated with genetic defects. Mutations of complement factor H (CFH) are the most common genetic defects that cause aHUS and often result in end-stage renal disease. Since CFH is mainly produced in the liver, liver transplantation (LT) has been performed in patients with defective CFH.

METHODS

The clinical courses of four kidney allograft recipients who lost their native kidney functions due to aHUS associated with a CFH mutation were reviewed.

RESULTS

Subject A underwent kidney transplantation (KT) twice, aHUS recurred and the allograft kidney failed within a few years. Subject B received a KT and soon experienced a recurrence of aHUS coinciding with infection. Her allograft kidney function has worsened, and she remains on plasma infusion therapy. Subject C underwent LT followed by KT. She is doing well without plasma infusion therapy after combined LT-KT for 3 years. Subject D received KT following LT and is now recurrence-free from aHUS.

CONCLUSION

In patients with aHUS associated with a CFH mutation, KT without LT was complicated with a recurrence of aHUS, which might lead to allograft loss. Conversely, LT was successful in preventing the recurrence of aHUS and thus might be another option for a recurrence-free life for aHUS patients associated with CFH mutation.