Eculizumab therapy in a child with hemolytic uremic syndrome and CFI mutation

Pediatric Immunodeficiency Caused by Complement Classical and Alternative Pathway Defects Due to a Homozygous CFI Variant: A Case Report

Complement factor I (CFI) deficiency is a rare primary immunodeficiency that disrupts the classical and alternative complement pathways, potentially causing severe recurrent infections and autoimmune manifestations in pediatric patients. However, the coexistence of both pathways in a pediatric patient is extremely uncommon. We report a seven-year-old patient with a rare primary immunodeficiency disorder who presented with recurrent middle ear infections, paronychia, gastrointestinal infections, and respiratory infections. Genetic testing revealed a previously unreported homozygous variant in the CFI gene (c.848A>G; p.D283G). Immunological testing showed a decrease in complement C3, CFI, and CFH levels in the patient. Interestingly, the patient presented with IgA vasculitis, with renal pathology showing deposits of immune complexes containing IgA, IgG, IgM, and C1q. By considering the child's condition and genetic test results, the child was treated symptomatically and received regular peritoneal dialysis treatment. Subsequently, the child's condition improved compared to before and was discharged from the hospital. This case highlights the importance of considering CFI deficiency in children with recurrent infections and abnormalities in both the classical and alternative complement pathways. Our findings expand the known phenotypic spectrum of CFI deficiency and contribute to understanding genotype-phenotype correlations in complement disorders.

Fatal Thrombotic Microangiopathy Case following Adeno-Associated Viral SMN Gene Therapy

This is the first fatal TMA following SMN AAV9 gene therapy in a child carrying a potential predisposing risk factor in the complement factor I gene.

A better understanding of the pathophysiology underlying TMA induced by AAV gene therapy is essential to ensure patient safety.

Adeno-associated virus (AAV) gene therapies are highly promising, such as the onasemnogene abeparvovec (Zolgensma) in spinal muscle atrophy (SMA). We report the first case of fatal systemic thrombotic microangiopathy (TMA) following onasemnogene abeparvovec in a 6-month-old child with SMA type 1, carrying a potential genetic predisposition in the complement factor I gene. Other cases of TMA have recently been reported after onasemnogene abeparvovec and after AAV9 minidystrophin therapy in Duchenne muscular dystrophy. The risk-benefit ratio of this therapy must therefore be assessed. Early recognition of TMA and targeted immunotherapy are fundamental to ensure the safety of patients treated with AAV gene therapies.

Complement gene variant effect on relapse of complement-mediated thrombotic microangiopathy after eculizumab cessation

Eculizumab is effective for complement-mediated thrombotic microangiopathy (CM-TMA), also known as atypical hemolytic uremic syndrome. Although lifelong therapy had been suggested, discontinuation does not universally lead to relapse. Comprehensive data evaluating risk factors for recurrence following discontinuation are limited. Our aim was to systematically review available literature assessing the role of complement genetic variants in this setting. Reports on CM-TMA and eculizumab withdrawal published before 1 January 2021, were included. Key reasons for patient exclusion were no follow-up after drug withdrawal and patients lacking complement genetic testing. Two-hundred eighty patients from 40 publications were included. Median age was 28 years, and 25 patients had a known history of renal transplant. Complement genetic variants were identified in 60%, most commonly in CFH (n = 59) and MCP/CD46 (n = 38). Of patients with a complement gene variant, 51.3% had ≥1 likely pathogenic/pathogenic variant whereas the remaining had variants of uncertain significance (VUS). Overall relapse rate after therapy discontinuation was 29.6%. Relapse rate was highest among patients with CFH variants and MCP/CD46 variants in canonical splice regions. VUS (P < .001) and likely pathogenic/pathogenic variants (P < .001) were associated with increased relapse. Presence of a renal allograft (P = .009); decreasing age (P = .029); and detection of variants in CFH (P < .001), MCP/CD46 (P < .001), or C3 (P < .001) were all independently associated with relapse after eculizumab discontinuation. Eculizumab discontinuation is appropriate in specific patients with CM-TMA. Caution should be exerted when attempting such a strategy in patients with high risk of recurrence, including a subgroup of patients with MCP/CD46 variants.

Atypical haemolytic uraemic syndrome: a case of rare genetic mutation

Complement-mediated kidney disease has been an evolving area in the field of nephrology. Atypical haemolytic uraemic syndrome (aHUS) is a rare thrombotic microangiopathy that affects multiple organs, particularly kidneys. The disease is characterised by a triad of haemolytic anaemia, thrombocytopenia and acute kidney injury (AKI). aHUS is most commonly caused by dysregulation of alternative complement pathway. In contrast to shiga toxin-associated haemolytic uraemic syndrome, diarrheal prodrome is usually absent in children with aHUS. We report a 2-year, 9-month-old boy who presented with acute dysentery and AKI. He had an unusual prolonged course of illness with hypocomplementaemia; hence, genetic testing was performed. He had a storming course in the hospital and succumbed to complications of the disease. Genetic study revealed digenic mutation in Complement Factor I and C3 Therefore, it is important to differentiate aHUS from other thrombotic microangiopathies to improve the outcome.

Rare Genetic Variants in Jewish Patients Suffering from Age-Related Macular Degeneration

Purpose: To identify rare genetic variants in early age-related macular degeneration (AMD) utilizing whole-exome sequencing (WES). Methods: Eight non-related early-AMD families of different Jewish ethnicities were ascertained. Initial mutation screening (phase-1) included common complement factor-H (CFH) p.Y402H; and age related maculopathy susceptibility 2 (ARMS2) p.A69S; and rare variants complement factor-I (CFI) p.V412M; and hemicentin1 (HMCN1) c.4163delC identified previously in our population. Four families, whose initial screening for the aforementioned variants was negative, underwent WES (phase-2). Bioinformatics filtering was based on functionality (from a panel of 234 genes with proven or presumed association to AMD); predicted severity; and frequency (rare variants with minor allele frequency <1%). When applicable, further screening for specific rare variants was carried out on additional cases of similar ethnicities and phenotypes (phase-3). Results: Phase-1 identified three families carrying CFI p.V412M mutation. WES analysis detected probable disease-related variants in three out of the remaining families. These included: a family with a variant in PLEKHA1 gene p.S177N; a family with previously reported variant p.R1210C in CFH gene; and two families with the C3 p.R735W variant. Conclusions: Rare, high-penetrance variants have a profound contribution to early-AMD pathogenesis. Utilization of WES in genetic research of multifactorial diseases as AMD, allows a thorough comprehensive analysis with the identification of previously unreported rare variants.

Haploidentical Hematopoietic Stem Cell Transplant Complicated by Atypical Hemolytic Uremic Syndrome and Kidney Transplant From the Same Donor With No Immunosuppression but C5 Inhibition

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is life-threatening condition particularly when complicating allograft hematopoietic stem cell transplant (HSCT). In the past, the outcome was very poor with the majority of patients reaching end-stage renal disease or dying with little or no chances of kidney transplant (KTx) due to the high risk of relapse. The availability of C5 inhibition has opened up significant therapeutic opportunities and has improved the outcome particularly if complement dysregulation (CD) is the underlying pathogenetic mechanism.

METHODS

We describe a peculiar case of a girl with aHUS complicating HSCT and her subsequent successful KTx received from the same donor thus performed without immunosuppression but anti-C5 inhibition.

RESULTS

Soon after HSCT performed for acute lymphoblastic leukemia, the patient developed a TMA due to CD and reached end-stage renal disease. After 2 years on dialysis, the patient received a KTx from her father who was already the HSCT donor. Given the full chimerism, no immunosuppressive agent was prescribed except a short (2 days) course of steroids and eculizumab to prevent aHUS relapse. Nine months after the KTx, the patient is well with normal renal function, no immunosuppression and continues eculizumab prevention of aHUS (1 infusion every 21 days).

CONCLUSIONS

All patients with transplant-associated thrombotic microangiopathy should be screened for the causes of CD. C5 inhibition with eculizumab is an important therapeutic resource to manage this complication. When KTx is necessary, immunosuppression can be safely withhold in case of same donor for both grafts and documented full chimerism.

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.

Clinical Relapses of Atypical HUS on Eculizumab: Clinical Gap for Monitoring and Individualised Therapy

Atypical hemolytic uremic syndrome (aHUS) is caused by dysregulation of the complement system. A humanised anti-C5 monoclonal antibody (eculizumab) is available for the treatment of aHUS. We present the first description of atypical HUS in a child with a coexistent diagnosis of a POL-III leukodystrophy. On standard eculizumab dosing regime, there was evidence of ongoing C5 cleavage and clinical relapses when immunologically challenged. Eculizumab is an effective therapy for aHUS, but the recommended doses may not be adequate for all patients, highlighting the need for ongoing efforts to develop a strategy for monitoring of treatment efficacy and potential individualisation of therapy.

Rare genetic variant in the CFB gene presenting as atypical hemolytic uremic syndrome and immune complex diffuse membranoproliferative glomerulonephritis, with crescents, successfully treated with eculizumab

BACKGROUND

Complement factor B gene (CFB) is an important component of the alternate pathway of complement activation that provides an active subunit that associates with C3b to form the C3 convertase, which is an essential element in complement activation. Among the complement-associated disorders, mutations and pathogenic variants in the CFB gene are relatively rare phenomena. Moreover, mutated CFB affiliation with immune-complex diffuse membranoproliferative glomerulonephritis (IC-MPGN) and atypical hemolytic uremic syndrome (aHUS) are considered a highly rare occurrence.

CASE PRESENTATION

We describe the clinical presentation, course, and pathological findings in a 7-year-old boy who has confirmed CFB heterozygous variants with pathological features compatible with IC-MPGN. Mutational analysis revealed a heterozygous variant p.Glu566Arg in exon 13 of the CFB gene. The patient did not respond to steroids and mycophenolate mofetil (MMF) therapy but responded clinically and biochemically to eculizumab treatment. This is the first case report of CFB alteration associated with IC-MPGN and aHUS that was successfully treated with eculizumab.

CONCLUSIONS

Heterozygous variants in the CFB gene can be pathogenic and associated with IC-MPGN and aHUS. Early diagnosis and prompt management can be essential in preventing end-stage renal disease. Eculizumab may provide an effective modality of treatment.

Current evidence on the discontinuation of eculizumab in patients with atypical haemolytic uraemic syndrome

Background. Atypical haemolytic uraemic syndrome (aHUS) is a rare, life-threatening disorder for which eculizumab is the only approved treatment. Life-long treatment is indicated; however, eculizumab discontinuation has been reported. Methods. Unpublished authors' cases and published cases of eculizumab discontinuation are reviewed. We also report eculizumab discontinuation data from five clinical trials, plus long-term extensions and the global aHUS Registry. Results. Of six unpublished authors' cases, four patients had a subsequent thrombotic microangiopathy (TMA) manifestation within 12 months of discontinuation. Case reports of 52 patients discontinuing eculizumab were identified; 16 (31%) had a subsequent TMA manifestation. In eculizumab clinical trials, 61/130 patients discontinued treatment between 2008 and 2015. Median follow-up post-discontinuation was 24 weeks and during this time 12 patients experienced 15 severe TMA complications and 9 of the 12 patients restarted eculizumab. TMA complications occurred irrespective of identified genetic mutation, high risk polymorphism or auto-antibody. In the global aHUS Registry, 76/296 patients (26%) discontinued, 12 (16%) of whom restarted. Conclusions. The currently available evidence suggests TMA manifestations following discontinuation are unpredictable in both severity and timing. For evidence-based decision making, better risk stratification and valid monitoring strategies are required. Until these exist, the risk versus benefit of eculizumab discontinuation, either in specific clinical situations or at selected time points, should include consideration of the risk of further TMA manifestations.

The complement system in age-related macular degeneration: A review of rare genetic variants and implications for personalized treatment

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The complement system plays a central role in age-related macular degeneration (AMD).

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Common and rare genetic variants in complement genes have been identified in AMD.

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Several of the rare variants affect the functioning of the complement system.

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However, a genetic association with AMD cannot always be proven.

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Functional assays can help identify patients for complement inhibiting therapies.

Age-related macular degeneration (AMD) is a progressive retinal disease and the major cause of irreversible vision loss in the elderly. Numerous studies have found both common and rare genetic variants in the complement pathway to play a role in the pathogenesis of AMD. In this review we provide an overview of rare variants identified in AMD patients, and summarize the functional consequences of rare genetic variation in complement genes on the complement system. Finally, we discuss the relevance of this work in light of ongoing clinical trials that study the effectiveness of complement inhibitors against AMD.

First-Line, Early and Long-Term Eculizumab Therapy in Atypical Hemolytic Uremic Syndrome: A Case Series in Pediatric Patients

INTRODUCTION

Studies relating to first-line, early, and long-term eculizumab treatment and outcomes in children with atypical hemolytic uremic syndrome (aHUS) are scarce and unclear. The aim of this case-series study was to evaluate the outcomes of first-line, early, and long-term eculizumab treatment in our aHUS patients.

MATERIALS AND METHODS

We reviewed the data from four pediatric patients with aHUS who were treated with eculizumab. In three of them, eculizumab was used as a first-line therapy, and the follow-up period was ≥2 years in three patients.

RESULTS

Plasma exchange could not be performed in any patient. Plasma infusions were used only in Patient 1 (a 14-month-old boy) for 8 days without any response. Therefore, eculizumab was started on day 11 after admission. Patient 2 (a 16-month-old boy), Patient 3 (an 11-year-old girl), and Patient 4 (a 32-month-old girl) were treated with eculizumab as a first-line therapy, which was started 2-4 days after admission. The dosage of eculizumab was adjusted according to body weight. The hematologic parameters (the time frames were 3-17 days) and C 3 (the time frames were 10-17 days) returned to normal in all patients after receipt of eculizumab. Although Patient 1 developed stage III chronic kidney disease, complete renal recovery occurred in Patients 2 and 4. Patient 3 also had reflux nephropathy with bilateral grade III vesicoureteral reflux and renal scars. Her creatinine clearance returned to the baseline value after receiving eculizumab. No complications related to eculizumab were observed in any patient during the follow-up period.

CONCLUSION

Eculizumab can be successfully used as a first-line therapy in pediatric aHUS patients. We observed that the early initiation of eculizumab was associated with the complete recovery of renal function.

Can eculizumab be discontinued in aHUS?: Case report and review of the literature

BACKGROUND

The management of atypical hemolytic uremic syndrome (aHUS) has evolved into better control of thrombotic microangiopathy (TMA) and recovery of renal functions since the recent introduction of the terminal complement cascade blocker, eculizumab, into clinical use. Better characterization of genotype-phenotype relations has become possible with genetic and clinical studies. However, these advances brought up some important issues, such as the possibility and timing of discontinuation of eculizumab and strategy of follow-up that need to be enlightened.

CASE SUMMARY

One of our aHUS cases with a novel complement factor H mutation, who developed unusual laboratory findings (thrombocytopenia and mild creatinine elevation without other features of TMA) following discontinuation of eculizumab was presented. Literature and case reports relevant to discontinuation of eculizumab in aHUS patients were reviewed.

CONCLUSION

Limited experience suggests that the risk of recurrence of TMA following discontinuation of eculizumab is relatively low for patients with MCP mutations, homozygous CFHR3/R1 deletions, anti-CFH antibodies, CFI mutations, and no identifiable mutations, whereas there is a major risk for patients with CFH mutations. Early detection of TMA recurrence and prompt retreatment with eculizumab seem to be efficient in controlling of TMA and restoration of kidney functions.

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.

An international consensus approach to the management of atypical hemolytic uremic syndrome in children

Atypical hemolytic uremic syndrome (aHUS) emerged during the last decade as a disease largely of complement dysregulation. This advance facilitated the development of novel, rational treatment options targeting terminal complement activation, e.g., using an anti-C5 antibody (eculizumab). We review treatment and patient management issues related to this therapeutic approach. We present consensus clinical practice recommendations generated by HUS International, an international expert group of clinicians and basic scientists with a focused interest in HUS. We aim to address the following questions of high relevance to daily clinical practice: Which complement investigations should be done and when? What is the importance of anti-factor H antibody detection? Who should be treated with eculizumab? Is plasma exchange therapy still needed? When should eculizumab therapy be initiated? How and when should complement blockade be monitored? Can the approved treatment schedule be modified? What approach should be taken to kidney and/or combined liver-kidney transplantation? How should we limit the risk of meningococcal infection under complement blockade therapy? A pressing question today regards the treatment duration. We discuss the need for prospective studies to establish evidence-based criteria for the continuation or cessation of anticomplement therapy in patients with and without identified complement mutations.

The genetic fingerprint of susceptibility for transplant-associated thrombotic microangiopathy

Transplant-associated thrombotic microangiopathy (TA-TMA) occurs frequently after hematopoietic stem cell transplantation (HSCT) and can lead to significant morbidity and mortality. There are no data addressing individual susceptibility to TA-TMA. We performed a hypothesis-driven analysis of 17 candidate genes known to play a role in complement activation as part of a prospective study of TMA in HSCT recipients. We examined the functional significance of gene variants by using gene expression profiling. Among 77 patients undergoing genetic testing, 34 had TMA. Sixty-five percent of patients with TMA had genetic variants in at least one gene compared with 9% of patients without TMA (P < .0001). Gene variants were increased in patients of all races with TMA, but nonwhites had more variants than whites (2.5 [range, 0-7] vs 0 [range, 0-2]; P < .0001). Variants in ≥3 genes were identified only in nonwhites with TMA and were associated with high mortality (71%). RNA sequencing analysis of pretransplantation samples showed upregulation of multiple complement pathways in patients with TMA who had gene variants, including variants predicted as possibly benign by computer algorithm, compared with those without TMA and without gene variants. Our data reveal important differences in genetic susceptibility to HSCT-associated TMA based on recipient genotype. These data will allow prospective risk assessment and intervention to prevent TMA in highly susceptible transplant recipients. Our findings may explain, at least in part, racial disparities previously reported in transplant recipients and may guide treatment strategies to improve outcomes.

Atypical aHUS: State of the art

Tremendous advances in our understanding of the thrombotic microangiopathies (TMAs) have revealed distinct disease mechanisms within this heterogeneous group of diseases. As a direct result of this knowledge, both children and adults with complement-mediated TMA now enjoy higher expectations for long-term health. In this update on atypical hemolytic uremic syndrome, we review the clinical characteristics; the genetic and acquired drivers of disease; the broad spectrum of environmental triggers; and current diagnosis and treatment options. Many questions remain to be addressed if additional improvements in patient care and outcome are to be achieved in the coming decade.

Eculizumab reduces complement activation, inflammation, endothelial damage, thrombosis, and renal injury markers in aHUS

Atypical hemolytic uremic syndrome (aHUS) is a genetic, life-threatening disease characterized by uncontrolled complement activation, systemic thrombotic microangiopathy (TMA), and vital organ damage. We evaluated the effect of terminal complement blockade with the anti-C5 monoclonal antibody eculizumab on biomarkers of cellular processes involved in TMA in patients with aHUS longitudinally, during up to 1 year of treatment, compared with in healthy volunteers. Biomarker levels were elevated at baseline in most patients, regardless of mutational status, plasma exchange/infusion use, platelet count, or lactate dehydrogenase or haptoglobin levels. Eculizumab reduced terminal complement activation (C5a and sC5b-9) and renal injury markers (clusterin, cystatin-C, β2-microglobulin, and liver fatty acid binding protein-1) to healthy volunteer levels and reduced inflammation (soluble tumor necrosis factor receptor-1), coagulation (prothrombin fragment F1+2 and d-dimer), and endothelial damage (thrombomodulin) markers to near-normal levels. Alternative pathway activation (Ba) and endothelial activation markers (soluble vascular cell adhesion molecule-1) decreased but remained elevated, reflecting ongoing complement activation in aHUS despite complete terminal complement blockade. These results highlight links between terminal complement activation and inflammation, endothelial damage, thrombosis, and renal injury and underscore ongoing risk for systemic TMA and progression to organ damage. Further research regarding underlying complement dysregulation is warranted. This trial was registered at www.clinicaltrials.gov as #NCT01194973.

Rare genetic variants in the CFI gene are associated with advanced age-related macular degeneration and commonly result in reduced serum factor I levels

To assess a potential diagnostic and therapeutic biomarker for age-related macular degeneration (AMD), we sequenced the complement factor I gene (CFI) in 2266 individuals with AMD and 1400 without, identifying 231 individuals with rare genetic variants. We evaluated the functional impact by measuring circulating serum factor I (FI) protein levels in individuals with and without rare CFI variants. The burden of very rare (frequency <1/1000) variants in CFI was strongly associated with disease (P = 1.1 × 10⁻⁸). In addition, we examined eight coding variants with counts ≥5 and saw evidence for association with AMD in three variants. Individuals with advanced AMD carrying a rare CFI variant had lower mean FI compared with non-AMD subjects carrying a variant (P < 0.001). Further new evidence that FI levels drive AMD risk comes from analyses showing individuals with a CFI rare variant and low FI were more likely to have advanced AMD (P = 5.6 × 10⁻⁵). Controlling for covariates, low FI increased the risk of advanced AMD among those with a variant compared with individuals without advanced AMD with a rare CFI variant (OR 13.6, P = 1.6 × 10⁻⁴), and also compared with control individuals without a rare CFI variant (OR 19.0, P = 1.1 × 10⁻⁵). Thus, low FI levels are strongly associated with rare CFI variants and AMD. Enhancing FI activity may be therapeutic and measuring FI provides a screening tool for identifying patients who are most likely to benefit from complement inhibitory therapy.

Efficacy and safety of eculizumab in atypical hemolytic uremic syndrome from 2-year extensions of phase 2 studies

Atypical hemolytic uremic syndrome (aHUS) is a rare, possibly life-threatening disease characterized by platelet activation, hemolysis and thrombotic microangiopathy (TMA) leading to renal and other end-organ damage. We originally conducted two phase 2 studies (26 weeks and 1 year) evaluating eculizumab, a terminal complement inhibitor, in patients with progressing TMA (trial 1) and those with long duration of aHUS and chronic kidney disease (trial 2). The current analysis assessed outcomes after 2 years (median eculizumab exposure 100 and 114 weeks, respectively). At all scheduled time points, eculizumab inhibited terminal complement activity. In trial 1 with 17 patients, the platelet count was significantly improved from baseline, and hematologic normalization was achieved in 13 patients at week 26, and in 15 patients at both 1 and 2 years. The estimated glomerular filtration rate (eGFR) was significantly improved compared with baseline and year 1. In trial 2 with 20 patients, TMA event-free status was achieved by 16 patients at week 26, 17 patients at year 1, and 19 patients at year 2. Criteria for hematologic normalization were met by 18 patients at each time point. Improvement of 15 ml/min per 1.73 m² or more in eGFR was achieved by 1 patient at week 26, 3 patients at 1 year, and 8 patients at 2 years. The mean change in eGFR was not significant compared with baseline, week 26, or year 1. Eculizumab was well tolerated, with no new safety concerns or meningococcal infections. Thus, a 2-year analysis found that the earlier clinical benefits achieved by eculizumab treatment of aHUS were maintained at 2 years of follow-up.

Podocyte dysfunction in atypical haemolytic uraemic syndrome

Genetic or autoimmune defects that lead to dysregulation of the alternative pathway of complement have been associated with the development of atypical haemolytic uraemic syndrome (aHUS), which is characterized by thrombocytopenia, haemolytic anaemia and acute kidney injury. The relationship between aHUS, podocyte dysfunction and the resultant proteinuria has not been adequately investigated. However, the report of mutations in diacylglycerol kinase ε (DGKE) as a cause of recessive infantile aHUS characterized by proteinuria, highlighted podocyte dysfunction as a potential complication of aHUS. DGKE deficiency was originally thought to trigger aHUS through pathogenetic mechanisms distinct from complement dysregulation; however, emerging findings suggest an interplay between DGKE and complement systems. Podocyte dysfunction with nephrotic-range proteinuria can also occur in forms of aHUS associated with genetic or autoimmune complement dysregulation without evidence of DGKE mutations. Furthermore, proteinuric glomerulonephritides can be complicated by aHUS, possibly as a consequence of podocyte dysfunction inducing endothelial injury and prothrombotic abnormalities.

Postpartum thrombotic microangiopathy revealed as atypical hemolytic uremic syndrome successfully treated with eculizumab: a case report

Introduction

Differential diagnosis of thrombotic microangiopathies can be difficult. Atypical hemolytic uremic syndrome is a rare, life-threatening disease caused by uncontrolled chronic activation of alternative complement pathway, resulting in microvascular thrombosis, organ ischemia and damage. Prognosis is poor: up to 65 percent of patients require dialysis or have kidney damage of varying severity or die despite plasma exchange/plasma infusion treatment.

Case presentation

We describe the case of a 23-year-old woman of Hellenic origin who, after a preeclampsia-induced premature delivery, developed thrombotic microangiopathy with renal failure, tonicoclonic seizures, anasarca edema and hypertension. Intensive plasma exchange was initiated twice daily, in parallel to dialysis for one month. Three months later, our patient was discharged with nondialysis-dependent renal failure and without signs of hemolysis. Three months after discharge our patient was readmitted with cardiomyopathy (left ventricular ejection fraction of 25 percent) and signs and symptoms of thrombotic microangiopathy. Our patient was diagnosed with atypical hemolytic uremic syndrome and was started on eculizumab (a complement inhibitor), which improved clinical and laboratory parameters. However, a transient pause in treatment resulted in thrombotic microangiopathy relapse, which was rapidly blocked with reintroduction of eculizumab treatment. During long-term eculizumab treatment, thrombotic microangiopathy manifestations were inhibited and renal and cardiac function restored, with no need for other invasive treatments.

Conclusions

Establishing the diagnosis of atypical hemolytic uremic syndrome in patients presenting with thrombotic microangiopathy is challenging since common symptoms are shared with other conditions like Shiga toxin-producing Escherichia coli hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. The described case illustrates the complexity and importance of rapid diagnosis in a rare disease and the need for appropriate and specific treatment for best long-term outcomes.

Atypical hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. The atypical form of HUS is a disease characterized by complement overactivation. Inherited defects in complement genes and acquired autoantibodies against complement regulatory proteins have been described. Incomplete penetrance of mutations in all predisposing genes is reported, suggesting that a precipitating event or trigger is required to unmask the complement regulatory deficiency. The underlying genetic defect predicts the prognosis both in native kidneys and after renal transplantation. The successful trials of the complement inhibitor eculizumab in the treatment of atypical HUS will revolutionize disease management.

Eculizumab in atypical haemolytic uraemic syndrome with severe cardiac and neurological involvement

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) is a rare disorder usually caused by dysregulation of the alternative complement pathway. Uncontrolled complement activation results in systemic complement-mediated thrombotic microangiopathy (TMA) and subsequent multi-organ damage. The two most common extrarenal complications comprise neurological and cardiovascular involvement. Eculizumab, a humanised anti-C5 monoclonal antibody, has recently been introduced as a therapy for this condition.

CASE-DIAGNOSIS/TREATMENT

A 19-month-old child suffering from aHUS with severe neurological involvement, dilated cardiomyopathy and renal impairment requiring dialysis received eculizumab as first-line treatment, initiated within 12 h of admission, resulting in significant improvements in her neurological state and normalisation of cardiac and renal function. These positive outcomes have been sustained with fortnightly eculizumab therapy (at the time of writing, on-going for 1 year). No further complications of TMA have occurred.

CONCLUSION

Severe cardiac involvement in a child with aHUS is an important indication for prompt, first-line treatment with eculizumab, resulting in rapid normalisation of cardiac function.

Eculizumab as first-line therapy for atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is a genetic, life-threatening, chronic disease that can affect patients of all ages. aHUS is caused by uncontrolled complement activation due to genetic defects of complement regulation. Plasma exchange or infusion has been used to manage aHUS and may transiently maintain hematologic variables in some patients, but as the underlying complement dysregulation persists, end-stage renal disease or death occurs in 33% to 40% of patients during the first clinical manifestation. Here we present a pediatric case showing that first-line eculizumab treatment successfully blocked the progression of thrombotic microangiopathy in aHUS.

Discontinuation of eculizumab maintenance treatment for atypical hemolytic uremic syndrome: a report of 10 cases

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy, and as many as 70% of patients with aHUS have mutations in the genes encoding complement regulatory proteins. Eculizumab, a humanized recombinant monoclonal antibody targeting C5, has been used successfully in patients with aHUS since 2009. The standard maintenance treatment requires life-long eculizumab therapy, but the possibility of discontinuation has not yet been tested systematically. We report the safety of discontinuing eculizumab treatment in 10 patients who stopped treatment with the aim of minimizing the risk of adverse reactions, reducing the risk of meningitis, and improving quality of life while also reducing the considerable treatment costs. Disease activity was monitored closely at home by means of urine dipstick testing for hemoglobin. During the cumulative observation period of 95 months, 3 of the 10 patients experienced relapse within 6 weeks of discontinuation, but then immediately resumed treatment and completely recovered. Our experience supports the possibility of discontinuing eculizumab therapy with strict home monitoring for early signs of relapse in patients with aHUS who achieve stable remission.

Eculizumab therapy for atypical haemolytic uraemic syndrome due to a gain-of-function mutation of complement factor B

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) is caused by dysregulated complement activation. A humanised anti-C5 monoclonal antibody has recently become available for treatment of this condition

CASE-DIAGNOSIS/TREATMENT

We present the first description of an infant with an activating mutation of complement factor B successfully treated with eculizumab. On standard doses she had evidence of ongoing C5 cleavage despite a good clinical response.

CONCLUSIONS

Eculizumab is effective therapy for aHUS associated with factor B mutations, but recommended doses may not be adequate for all patients.

Complement therapy in atypical haemolytic uraemic syndrome (aHUS)

Central to the pathogenesis of atypical haemolytic uraemic syndrome (aHUS) is over-activation of the alternative pathway of complement. Inherited defects in complement genes and autoantibodies against complement regulatory proteins have been described. The use of plasma exchange to replace non-functioning complement regulators and hyper-functional complement components in addition to the removal of CFH-autoantibodies made this the ‘gold-standard’ for management of aHUS. In the last 4 years the introduction of the complement inhibitor Eculizumab has revolutionised the management of aHUS. In this review we shall discuss the available literature on treatment strategies to date.