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Background: Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA) related to congenital mutations impeding control of the alternative pathway of complement. Following approval of the complement C5 inhibitor eculizumab by the European Medicines Agency and the US Food and Drug Administration, initial guidelines suggested lifelong therapy. Yet, growing evidence indicates that discontinuation of eculizumab, or its long-acting form ravulizumab, is possible for many patients. This mixed-methods study sought to explore international experts' perspectives and experiences related to treatment duration in adult patients with aHUS, while also estimating the financial and potential health consequences of early discontinuation., Methods: Between January and December 2023, we conducted 10 qualitative interviews with experts in the treatment of aHUS, based upon which we constructed a quantitative decision tree, designed to estimate time on treatment and treatment- and disease-related adverse events., Results: Thematic analysis of the interview data identified four main themes: (1) Concerns and prior experience; (2) High-risk vs. low-risk groups; (3) Patient preference and adherence; and (4) Funding for monitoring and re-treatment. Although most interviewees were in favour of considering treatment discontinuation for many patients (citing the high cost, burden, and potential side effects of lifelong treatment as key reasons), a prior negative experience of discontinuation seemed to make others more reluctant to stop. Deciding which patients required lifelong treatment and which not involved consideration of a wide range of factors, including patient- and system-related factors. Cost-consequence analysis demonstrated the financial savings associated with early treatment discontinuation at the expense of increased risk of recurrent TMA events. Close monitoring for these events had the potential to minimise any long-term injury, primarily renal, with an estimated one event per 100 patient years. For patients at high risk of TMA and with poor adherence to monitoring, rates of renal injury rose to three events per 100 patient years., Conclusions: aHUS treatment protocols are changing globally in response to new clinical evidence. Against this backdrop, our mixed-methods study provides compelling evidence on the complexity of factors influencing treatment discontinuation decisions in aHUS, as well as the financial and health consequences of early discontinuation., Competing Interests: Declarations Ethics approval and consent to participate The study was approved by the Biomedical Research Alliance of New York LLC Organizational Review Board and the Weill Cornell Institutional Review Board (Study Protocol: 21-07023785). Written informed consent was obtained from all experts participating in the interviews. Consent for publication The consent process involved informing all participants that interviews would form the basis of a publication and that no identifying information would be used. Competing interests AB and JL have received consultancy payments from Alexion Pharmaceuticals in addition to the funding reported here., (© 2024. The Author(s).)

What Is This Summary About?: This summary gives an overview of three published articles that report the results of research studies of ravulizumab, an approved treatment for people with atypical hemolytic uremic syndrome (often shortened to aHUS). This is a rare and serious condition where blood clots form in small blood vessels. Blood vessels are structures that transport blood around the body. Blood clots are the body's way of stopping someone from bleeding too much. However, if they form when they are not needed, they can cause harm. In atypical hemolytic uremic syndrome, the blood clots can cause injury to organs like the kidney. In the three studies, the researchers wanted to know if ravulizumab could decrease the formation of these clots and improve kidney function. Children who had never received ravulizumab or a similar treatment took part in the first study. Adults who had never received ravulizumab or a similar treatment took part in the second study. In the third study, children whose disease was already controlled by a medication called eculizumab switched to ravulizumab. Ravulizumab is dosed less frequently than eculizumab. The researchers looked at kidney function and the levels of different blood components to see how well the treatment was working. They also monitored the adverse effects that participants experienced., What Were the Results?: Across the three studies, ravulizumab improved indicators of blood clotting in small vessels and improved kidney function in both children and adults. In addition, ravulizumab was similarly effective to eculizumab for children who were already receiving eculizumab and switched to ravulizumab. Overall, the adverse effects that people experienced with ravulizumab were manageable., What Do the Results Mean?: These studies showed that ravulizumab is a treatment option for children and adults with aHUS. In addition, a switch to ravulizumab can be considered for children who are already responding well to eculizumab and would benefit from less frequent dosing.

Background: Between 5 and 50% of atypical hemolytic uremic syndrome (aHUS) cases in children are caused by autoantibodies against complement factor H (CFH). Given the acquired autoimmune nature of the disease, plasma exchange (PE) and various immunosuppressive treatments have been used. More recently, eculizumab has been proposed., Methods: In this multicenter, retrospective study, we report outcomes of 12 children with anti-FH antibody-associated HUS treated with eculizumab associated with various immunosuppressive regimens., Results: Patients were treated with eculizumab for 15.5 [9.5;23.0] months and 3 received PE or IgG adsorption. Three patients received mycophenolate mofetil (MMF) alone, 1 patient received MMF and steroids, 1 patient received MMF and rituximab, 3 patients received MMF/steroids and rituximab, and 4 patients did not receive any immunosuppression. Anti-FH antibody levels significantly decreased but no difference was observed based on the immunosuppressive regimen. Eculizumab was discontinued in 7/10 patients after 11 [7.5;15.5] months and MMF in 6/8 patients after 36 [35;40] months. Anti-FH titers at MMF discontinuation ranged from 257 to 3425 UI/L. None of these patients relapsed and eGFR at last follow-up was above 70 mL/min/1.73 m 2 in all patients., Conclusions: Eculizumab is effective and safe in inducing and maintaining remission in aHUS secondary to anti-FH antibodies and renders reduction of anti-FH titers less urgent. Anti-FH antibody titers decreased in most patients irrespective of the immunosuppressive treatment chosen, so that a strategy consisting of combining eculizumab with MMF monotherapy seems sufficient at least in non-Indian or less severe forms of anti-FH antibody-associated HUS., (© 2024. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Systemic lupus erythematosus (SLE) can present with a diverse array of hematologic manifestations, among which atypical hemolytic uremic syndrome (aHUS) is a rare entity. SLE-triggered aHUS has significant morbidity and mortality without timely intervention, yet its frequency remains uncertain and optimal strategies for complement-directed therapies are largely expert-driven. We performed a comprehensive literature review and present a case of a 23-year-old female newly diagnosed with SLE/class IV lupus nephritis who developed aHUS that rapidly responded to the C5 antagonist, eculizumab. Review of the current literature identified forty-nine published cases of SLE with concurrent aHUS and revealed a predilection for aHUS in younger SLE patients, concurrent presentation with lupus nephritis, anti-dsDNA positivity, and complement system abnormalities. Over seventy percent of cases used eculizumab as complement-directed therapy with a trend towards faster time to improvement in laboratory parameters, though reported outcomes were highly variable. Early recognition of aHUS in SLE is pivotal in guiding appropriate therapeutic interventions, and prompt initiation of eculizumab may reduce the potential morbidity associated with plasmapheresis and additional immunosuppression. While eculizumab showcases promising results, its optimal timing and duration remain elusive. An understanding of a patients' complement genetics could aid management strategies, and ongoing research into complement-targeted therapies offers promising avenues for both SLE and aHUS treatment., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Atypical hemolytic uremic syndrome (aHUS) is a complement-mediated thrombotic microangiopathy sometimes associated with germline variants in genes of the complement system. Clinical findings of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury arise due to aberrant complement protein activation in the circulation. A 13-month-old boy with metastatic neuroblastoma (NB) developed aHUS during his first cycle of induction chemotherapy with germline testing revealing a complement factor H (CFH) gene mutation, currently classified as a variant of uncertain significance (VUS). Now he is in disease remission after successful complement blockade therapy, thus highlighting a unique presentation of aHUS in a patient with newly diagnosed NB., (© 2024 Wiley Periodicals LLC.)

Background: Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy. Genetic defects in the alternative complement (AP) pathway have been identified in 60-70% of individuals. Eculizumab is recommended as a first-line therapy., Methods: We collected the clinical data of a pediatric patient with aHUS accompanied by protein-losing enteropathy (PLE). Genetic testing was performed. Related literature on aHUS combined with PLE was reviewed., Results: A 15-year-old Chinese girl was diagnosed with aHUS at 3.7 years of age and experienced five episodes; her symptoms completely resolved with plasma treatment. Severe gastrointestinal symptoms and hypoalbuminemia presented after the first episode, and PLE was diagnosed. A novel homozygous CD46 variant was identified, and FACS revealed significantly decreased CD46 expression. She presented at a recent relapse with persistent GI symptoms and headache and progressed to chronic kidney failure; peritoneal dialysis was initiated. Eculizumab was given 8 months after the last recurrence. Surprisingly, PLE was cured. Afterward, dialysis was discontinued, and eGFR recovered to 44.8 ml/min/1.73 m 2 . A review of the literature indicated that PLE with thrombosis was caused by CD55 variants via hyperactivation of the AP system. We report an aHUS patient with PLE caused by CD46 variants. Symptoms of both PLE and aHUS were significantly alleviated in our patient and patients with CD55 variants treated with eculizumab, indicating that PLE was a new symptom of aHUS in our patient with a CD46 variant., Conclusions: Our case expands the phenotype of aHUS caused by a CD46 mutation and provides evidence of the efficacy of eculizumab after a long phase of chronic kidney failure., (© 2024. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Background: No reports have shown histological changes before and after anti-C5 monoclonal antibody treatment in patients with atypical hemolytic uremic syndrome (aHUS). Here, we report a rare case of complement-mediated aHUS with a complement factor H (CFH) mutation and anti-CFH antibodies who underwent multiple kidney biopsies., Case Presentation: A 53-year-old woman developed aHUS with CFH gene mutation [c.3572C > T (p. Ser1191 Leu)] and anti-CFH antibodies. Her father had succumbed to acute kidney injury (AKI) in his 30 s. She exhibited AKI, thrombocytopenia, and hemolytic anemia with schistocytes. After improving the platelet count with one session of plasma exchange, a kidney biopsy was performed one month after the onset of symptoms. Blood vessel thrombosis, obvious endothelial swelling, endocapillary hypercellularity, and subendothelial exudative lesions in the glomeruli and arterioles were detected. Anti-C5 monoclonal antibody treatment with eculizumab immediately improved disease activity. A second biopsy 3 months later revealed marked improvement of endothelial injuries with residual membrane double contours and exudative lesions. A third biopsy at 17 months after gradual improvement of kidney function showed a further decrease of double contours along with alterations of the exudative lesions to fibrous intimal thickening., Conclusions: This is the first report showing the pathophysiology of aHUS in the kidneys and the efficacy of anti-C5 monoclonal antibody treatment by presenting serial kidney pathological features before and after anti-C5 monoclonal antibody treatment. Since her CFH mutation was considered the most important pathological condition, treatment centered on eculizumab was administered, resulting in a good long-term prognosis. In addition, kidney pathological resolution in aHUS occurred over 1 year after anti-C5 monoclonal antibody treatment., (© 2024. The Author(s).)

Background: The complement factor 5 (C5)-inhibitor eculizumab has been established as standard-of-care for the treatment of atypical hemolytic uremic syndrome (aHUS). In 2021, the long-acting C5-inhibitor ravulizumab was approved, extending intervals of intravenous treatment from two to eight weeks resulting in improvement of quality of life for patients and lowering direct and indirect therapy associated costs., Methods: This multicenter, retrospective data analysis of 32 adult patients with aHUS (including 10 kidney transplant recipients) treated with eculizumab for at least three months and switched to ravulizumab aims to evaluate the safety and efficacy of switching medication in the real-world setting. Hematologic parameters, kidney function, concurrent therapy and aHUS associated events were evaluated three months before and until up to 12 months after switching to ravulizumab., Results: Mean age (range) at ravulizumab initiation was 41 years (19-78 years) and 59% of the patients were female. Genetic analysis was available for all patients with 72% showing a pathogenic variant. Median time (range) on eculizumab before switching was 20 months (3-120 months). No new events of TMA or worsening of renal function were reported during up to 12 months of follow-up during ravulizumab treatment., Conclusions: This is the largest, non-industry derived, multi-center retrospective analysis of adult patients with aHUS switching C5-inhibitor treatment from eculizumab to ravulizumab in the real-world setting. Switching to ravulizumab was safe and efficient resulting in sustained hematological stability and preservation of renal function., (© 2024. The Author(s).)

Crovalimab ( ®; PiaSky) is a humanized, anti-complement component C5 (anti-C5) recycling monoclonal antibody developed by Chugai Pharmaceutical, in collaboration with Roche, which is being investigated for the treatment of complement-mediated diseases, including paroxysmal nocturnal haemoglobinuria (PNH), atypical haemolytic uremic syndrome, lupus nephritis and sickle cell disease. Crovalimab targets C5, inhibiting its cleavage to C5a and C5b, thus blocking the terminal complement pathway and preventing intravascular haemolysis in PNH. Crovalimab is designed to bind to the antigen repeatedly, resulting in sustained complement inhibition at a lower dosage, and allowing for once-monthly subcutaneous administration. In February 2024, subcutaneous crovalimab received its first approval in China for the treatment of adolescents and adults (aged ≥ 12 years) with PNH who have not been previously treated with complement inhibitors. Crovalimab has since been approved in Japan in March for use in the treatment of PNH, including in treatment-naïve and previously treated patients. Crovalimab is also under regulatory review for the treatment of naïve and previously treated patients with PNH in multiple countries, including the USA and the European Union. This article summarizes the milestones in the development of crovalimab leading to this first approval in China for the treatment of PNH., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Atypical haemolytic uraemic syndrome (aHUS) is a rare thrombotic microangiopathy resulting from dysregulation of the alternative complement pathway, leading to multi-organ dysfunction and chronic kidney disease. Eculizumab is an anti-C5 monoclonal antibody therapy that has significantly improved aHUS disease control and patient outcomes, however it requires fortnightly intravenous dosing. This often necessitates long term central access and a high hospital attendance burden. Ravulizumab is a novel, next-generation anti-C5 monoclonal antibody engineered from eculizumab to reduce endosomal degradation of the antibody, increasing the dosing interval up to 8 weeks., Case Series: In this retrospective case series we present the transition of three children with aHUS from eculizumab to ravulizumab from a single tertiary paediatric nephrology service. All patients underwent genomic and immunological work up for aHUS, with no cause found. After stabilisation with eculizumab, two patients developed macrovascular thrombotic complications associated with indwelling central vascular catheters, ultimately leading to central access failure. All patients were transitioned from eculizumab to ravulizumab without relapse of aHUS. One patient successfully underwent deceased donor kidney transplantation with ravulizumab for complement inhibition. All patients have transitioned to peripheral access for infusions given the reduced frequency of dosing, maintaining good control of aHUS for 2-4 years., Conclusion: Ravulizumab permits sufficiently reduced frequency of infusion to allow for administration by peripheral cannulation - removing the risks of long term central vascular access often required to deliver eculizumab to paediatric patients., (© 2024 The Authors. Journal of Paediatrics and Child Health published by John Wiley & Sons Australia, Ltd on behalf of Paediatrics and Child Health Division (The Royal Australasian College of Physicians).)

Background: Atypical-hemolytic uremic syndrome (aHUS) is a rare thrombotic microangiopathy often due to uncontrolled complement activation, characterized by high risk of end-stage kidney disease (ESKD). Eculizumab has improved the outcome, however, its efficacy varies among patients and its discontinuation is debated., Methods: To identify characteristics associated with treatment response, we analyzed 244 aHUS patients referred to our center. Patients were classified according to the presence/absence of complement abnormalities and/or triggers at onset in 4 categories: (1) primary (complement abnormality without trigger), (2) secondary (trigger without complement abnormality), (3) combined (trigger and complement abnormality), (4) idiopathic (no trigger, no complement abnormality). Response to treatment was evaluated by comparing the response to eculizumab with that of conventional therapy. Short- and long-term outcomes were evaluated with the relapse rate after discontinuation of C5-inhibition., Results: Patients had a better outcome with eculizumab compared to conventional treatment, with a response rate of 81.9% vs 56.9%, p < 0.001 and a long-term cumulative incidence of ESKD of 5.8% vs 22.5% (hazard ratio 0.25, 95% confidence interval: 0.10-0.80). The excellent global response was driven by the primary and combined groups (89.8% vs 54.0% and 89.3% vs 54.2%, respectively). The relapse rate following discontinuation of the C5-inhibitor was as high as 66.7% in the primary group, 18.7% in the combined, and 0% in the secondary and idiopathic groups., Conclusions: Our data show a better outcome in aHUS patients treated with C5-inhibition, particularly in the primary and combined forms, which have a high risk of relapse after discontinuation that is not observed in the secondary and idiopathic forms., (© 2024. The Author(s) under exclusive licence to Italian Society of Nephrology.)

Antiphospholipid syndrome nephropathy includes a variety of histological lesions, including thrombotic microangiopathy, which is not included among the diagnostic criteria of antiphospholipid syndrome. Whereas in secondary antiphospholipid syndrome, e.g. to systemic lupus erythematosus, there is emerging evidence of a benefit from complement blockade with eculizumab, optimal treatment of primary antiphospholipid syndrome-associated thrombotic microangiopathy is currently unknown. We report the case of a 36-year-old male patient with primary antiphospholipid syndrome-associated thrombotic microangiopathy, presenting with a clinical picture of atypical hemolytic-uremic syndrome with frequent relapses, treated with eculizumab (four 900 mg weekly doses followed by 1200 mg fortnightly infusions) leading to resolution of hemolysis, long-term remission and partial kidney function recovery (peak serum creatinine 3.8 mg/dL, decreased and stabilized around 2.5 mg/dL) over a follow up period of over 2 years., (© 2023. The Author(s) under exclusive licence to Italian Society of Nephrology.)

Aims: Eculizumab is a monoclonal antibody targeting complement protein C5 used in renal diseases. As recommended dosing regimen leads to unnecessarily high concentrations in some patients, tailored dosing therapeutic drug monitoring was proposed to reduce treatment cost. The objectives of the present work were (i) to investigate the target-mediated elimination of eculizumab and (ii) whether a pharmacokinetic model integrating a nonlinear elimination allows a better prediction of eculizumab concentrations than a linear model., Methods: We analysed 377 eculizumab serum concentrations from 44 patients treated for atypical haemolytic uraemic syndrome and C3 glomerulopathy with a population pharmacokinetic approach. Critical concentrations (below which a non-log-linear decline of concentration over time is evidenced) were computed to estimate the relevance of the target-mediated elimination. Simulations of dosing regimens were then performed to predict probabilities of target attainment (i.e. trough >100 mg/L)., Results: Pharmacokinetics of eculizumab was nonlinear and followed a mixture of first-order (CL = 1.318 mL/day/kg) and Michaelis-Menten elimination (V max  = 26.07 mg/day, K m  = 24.06 mg/L). Volume of distribution (72.39 mL/kg) and clearance were weight-dependent. Critical concentrations (V max /CL) ranged from 144.7 to 759.7 mg/L and were inversely related to body weight (P = .013). Nonlinearity was thus noticeable at therapeutic concentrations. Simulations predicted that 1200 mg of eculizumab every 21 days would allow 85% and 76% of patients to maintain a therapeutic exposure, for 50 or 90 kg body weight, respectively., Conclusions: Our study investigates the nonlinear elimination of eculizumab and discusses the importance of accounting for eculizumab target-mediated elimination in therapeutic drug monitoring., (© 2024 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Historically, the complement system (classical, lectin, alternative, and terminal pathways) is known to play a crucial role in the etiopathogenesis of many kidney diseases. Direct or indirect activation in these settings is revealed by consumption of complement proteins at the serum level and kidney tissue deposition seen by immunofluorescence and electron microscopy. The advent of eculizumab has shown that complement inhibitors may improve the natural history of certain kidney diseases. Since then, the number of available therapeutic molecules and experimental studies on complement inhibition has increased exponentially. In our narrative review, we give a summary of the main complement inhibitors that have completed phase II and phase III studies or are currently used in adult and pediatric nephrology. The relevant full-text works, abstracts, and ongoing trials (clinicaltrials.gov site) are discussed. Data and key clinical features are reported for eculizumab, ravulizumab, crovalimab, avacopan, danicopan, iptacopan, pegcetacoplan, and narsoplimab. Many of these molecules have been shown to be effective in reducing proteinuria and stabilizing kidney function in different complement-mediated kidney diseases. Thanks to their efficacy and target specificity, these novel drugs may radically improve the outcome of complement-mediated kidney diseases, contributing to an improvement in our understanding of their underlying pathophysiology., (© 2023. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Thrombotic microangiopathies (TMA) are usually associated with hematological features (RH-TMA). The epidemiology of TMA limited to kidneys (RL-TMA) is unclear Therefore, patients with TMA and native kidney biopsies were identified during 2009-2022 in 20 French hospitals and results evaluated. RL-TMA was present in 341/757 (45%) patients and associated with lower creatinine levels (median 184 vs 346 μmol/L) than RH-TMA. RL-TMA resulted from virtually all identified causes, more frequently from anti-VEGF treatment and hematological malignancies but less frequently from shigatoxin-associated hemolytic uremic syndrome (HUS), systemic sclerosis, gemcitabine and bacterial infection, and even less frequently when three or more causes/triggers were combined (RL-TMA: 5%; RH-TMA: 12%). RL-TMA was associated with significantly lower major cardiovascular events (10% vs 20%), kidney replacement therapy (23% vs 43%) and death (12% vs 20%) than RH-TMA during follow-up (median 28 months). Atypical HUS (aHUS) was found in 326 patients (RL-TMA: 43%, RH-TMA: 44%). Among the 69 patients with proven complement-mediated aHUS, eculizumab (anti-C5 therapy) was used in 43 (62%) (RL-TMA: 35%; RH-TMA: 71%). Among the 257 other patients with aHUS, including 51% with RL-TMA, eculizumab was used in 29 but with unclear effects of this treatment. Thus, RL-TMA represents a very high proportion of patients with TMA and results from virtually all known causes of TMA and includes 25% of patients with complement-mediated aHUS. Adverse outcomes of RL-TMA are lower compared to RH-TMA but remain significant. Anti-C5 therapy was rarely used in RL-TMA, even in proven complement-mediated aHUS, and its effects remain to be assessed., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Background: Complement-mediated thrombotic microangiopathy (CM-TMA), also called atypical hemolytic uremic syndrome (aHUS), is a difficult-to-diagnose rare disease that carries severe morbidity and mortality. Anti-C5 monoclonal antibodies (aC5-mab) are standard treatments, but large studies and long-term data are scarce. Here, we report our single institution experience to augment the knowledge of CM-TMA treated with aC5-mab therapy., Methods: We aimed to assess the short and long-term effects of aC5-mab in patients diagnosed with CM-TMA treated outside of a clinical trial. This was a retrospective study. We included all patients diagnosed with CM-TMA and treated with aC5-mab at our institution. There were no exclusion criteria. Endpoints included complete TMA response (CR) defined as normalization of hematological parameters and ≥25% improvement in serum creatinine (Cr) from baseline in patients with renal disease, relapse defined as losing the previously achieved CR, morbidity, adverse events, and survival., Results: We found 28 patients with CM-TMA treated with aC5-mab. The median age was 50 years. Baseline laboratories: platelet counts 93 × 10 9 /L, hemoglobin 8.6 g/dL, lactate dehydrogenase 1326 U/L, serum Cr 4.7 mg/dL, and estimated glomerular filtration rate 19 mL/min. One individual was on renal replacement therapy (RRT) and 10 initiated RRT within 5 days of the first dose of aC5-mab. Genetic variants associated with CM-TMA included mutations in C3, CFB, CFH, CFHR1/3, CFI, and MCP. The mean duration of hospitalization was 24 days. The median time to initiation of aC5-mab was 10 days. Sixteen subjects received RRT. At the time of hospital discharge, 27 were alive, 14 remained on RRT, and 4 had a CR. At 6 months, 23 patients were alive, 18 continued aC5-mab, 8 remained on RRT, and 9 had a CR. At the last follow-up visit past 6 months, 20 were alive, 14 continued aC5-mab, 5 remained on RRT, 12 had a CR, and 1 was lost to follow-up., Conclusions: Our study provides real-world experience and insight into the long-term outcomes of CM-TMA treated with aC5-mab. Our findings validate that CM-TMA is an aggressive disease with significant morbidity and mortality, and confirm that aC5-mab is a relatively effective therapy for CM-TMA. Our study adds practical, real-world experience to the literature, but future research remains imperative., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Secondary atypical hemolytic uremic syndrome (secondary aHUS) is a heterogeneous group of thrombotic microangiopathies (TMA) associated with various underlying conditions. Unlike primary aHUS, there is still no hard evidence on the efficacy of complement blockade in secondary aHUS, since the two main series that investigated this subject showed discrepant results. Our work aims to reassess the efficacy of eculizumab in treating secondary aHUS., Methods: Observational, retrospective, single-center study, in which we analyzed the hematological and renal evolution of 23 patients diagnosed with secondary aHUS who received treatment with eculizumab and compared them with a control cohort of 14 patients. Complete renal response was defined as the recovery of renal function before the event, partial renal response as a recovery of 50% of lost glomerular filtration rate, and hematological response as normalization of hemoglobin and platelets., Results: We found no statistically significant differences in baseline characteristics or disease severity between both groups. After a median of 5 doses of eculizumab, the group of patients who received complement blockade presented a significant difference in renal response (complete in 52.3% of patients and partial in 23.8%) compared to the control cohort (complete response 14.3% and partial of 14.3%). Rates of hematological remission were similar in both groups (90.9% in the eculizumab cohort and 85.7% in the control cohort)., Conclusion: Early and short-term use of eculizumab in patients with secondary aHUS could be an effective and safe therapeutic option, assuring better renal recovery compared to patients who do not receive complement blockade., Competing Interests: EM has received honoraria’s as speaker in conferences sponsored by AZ ALEXION, CSL VIFOR, OTSUKA and GSK. EG has received honoraria’s as speaker in conferences sponsored by AZ ALEXION. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Cordero, Cavero, Gutiérrez, Trujillo, Sandino, Auñón, Rivero and Morales.)

Objective: The objective of the study was to analyze and describe the concentrations of eculizumab and the complement blockade in patients with atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy, and to define a therapeutic margin where there is a high probability of achieving therapeutic efficacy., Methods: Observational, ambispective, and multicenter study that included adult and pediatric patients diagnosed with aHUS and C3 glomerulopathy from September 2020 to October 2022 in 5 hospitals in Spain. Eculizumab was administered at the doses recommended by the data sheet according to the European Medicines Agency (EMA). Pre- and post-dose concentrations of eculizumab were determined, as well as blockade of the classical complement pathway (CH50). Sociodemographic and clinical data were collected, and pharmacokinetic parameters were calculated. To establish the cut-off point for eculizumab concentrations that predicted complement blockade, Receiver Operating Characteristic (ROC) curve analysis was performed. Lastly, the Kruskal-Wallis test was used to contrast the differences in different parameters according to eculizumab concentrations., Results: Twenty-five patients were included, 19 adults (76.0%) and 6 pediatrics (24.0%), with median ages of 43.4 (interquartile range (IQR) 35.7-48.8) and 10.1 (IQR 9.6-11.3) years, respectively. Of these, 22 (88.0%) patients were diagnosed with aHUS and 3 (12.0%) with C3 glomerulopathy. A total of 111 eculizumab concentrations were determined. Mean pre- and post-dose concentration values detected during the maintenance phase were 243.8 (SD 240.6) μg/mL and 747.4 (standard deviation (SD) 444.3) μg/mL, respectively. Increased complement blockade was observed at higher pre-dose concentrations (P = .002) and decreased serum creatinine at both higher pre- and post-dose concentrations (P = .001 and P = .017, respectively). Using ROC curves, it was determined that a pre-dose concentration >149.0 μg/mL was optimal to achieve complement blockade, with an AUC of 0.87 (0.78-0.95). Finally, high inter-individual (48.9% variation coefficient (CV)) with low intra-individual variabilities (11.9% CV) in eculizumab clearance were observed., Conclusions: The present study reports supratherapeutic concentrations of eculizumab in patients with aHUS, and defines higher concentrations than those described in the data sheet to achieve blockade, thus encouraging the personalization of treatment with eculizumab., Competing Interests: Conflict of interest None declared., (Copyright © 2023 Sociedad Española de Farmacia Hospitalaria (S.E.F.H). Publicado por Elsevier España, S.L.U. All rights reserved.)

Objective: The objective of the study was to analyze and describe the concentrations of eculizumab and the complement blockade in patients with atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy, and to define a therapeutic margin where there is a high probability of achieving therapeutic efficacy., Methods: Observational, ambispective and multicenter study that included adult and pediatric patients diagnosed with aHUS and C3 glomerulopathy from September 2020 to October 2022 in five hospitals in Spain. Eculizumab was administered at the doses recommended by the data sheet according to the European Medicines Agency (EMA). Pre-dose and post-dose concentrations of eculizumab were determined, as well as blockade of the classical complement pathway (CH50). Sociodemographic and clinical data were collected, and pharmacokinetic parameters were calculated. To establish the cut-off point for eculizumab concentrations that predicted complement blockade, Receiver Operating Characteristic (ROC) curve analysis was performed. Lastly, the Kruskal-Wallis test was used to contrast the differences in different parameters according to eculizumab concentrations., Results: Twenty-five patients were included, 19 adults (76.0%) and 6 pediatrics (24.0%), with median ages of 43.4 (IQR 35.7-48.8) and 10.1 (IQR 9.6-11.3) years, respectively. Of these, 22 (88.0%) patients were diagnosed with aHUS and 3 (12.0%) with C3 glomerulopathy. A total of 111 eculizumab concentrations were determined. Mean pre-dose and post-dose concentration values detected during the maintenance phase were 243.8 (SD 240.6) μg/mL and 747.4 (SD 444.3) μg/mL, respectively. Increased complement blockade was observed at higher pre-dose concentrations (p=0.002) and decreased serum creatinine at both higher pre- and post-dose concentrations (p=0.001 and p=0.017, respectively). Using ROC curves, it was determined that a pre-dose concentration >149.0 μg/mL was optimal to achieve complement blockade, with an AUC of 0.87 (0.78-0.95). Finally, high inter-individual (48.9% CV) with low intra-individual variabilities (11.9% CV) in eculizumab clearance were observed., Conclusions: The present study reports supratherapeutic concentrations of eculizumab in patients with aHUS, and defines higher concentrations than those described in the data sheet to achieve blockade, thus encouraging the personalization of treatment with eculizumab., (Copyright © 2023 Sociedad Española de Farmacia Hospitalaria (S.E.F.H). Publicado por Elsevier España, S.L.U. All rights reserved.)

ABP 959 is being developed as a biosimilar to Soliris® (eculizumab) reference product (RP), which was approved under orphan designation for a group of rare diseases including paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), generalized myasthenia gravis (gMG), and neuromyelitis optica spectrum disorder (NMOSD). Development of biosimilars for therapeutics approved for rare disease indications must provide scientific rationale based on the totality of evidence (TOE). To support the TOE and the scientific justification for extrapolation to all approved indications for eculizumab RP, including but not limited to aHUS and NMOSD, we utilized simulated ex-vivo pharmacodynamic (PD) assessments to compare the complement component 5 (C5) inhibitory activity of ABP 959 and the RP. Hemolysis activity of CH50 and AH50, and Wieslab CP, AP, and LP endpoints represent the three complement activation pathways (classical, alternative, and lectin), all of which share the terminal pathway and require C5 for activity. These endpoints were evaluated in normal serum, simulated aHUS serum, and simulated NMOSD serum to provide a robust comparison. The results support the conclusion that ABP 959 and eculizumab RP exhibit highly similar inhibition of C5 function regardless of the type of serum used. This work presents a full comparison of the effect of C5 inhibition across five complement functional assays. Using this approach to confirm functional similarity of ABP 959 with eculizumab RP contributes to the TOE for biosimilarity and provides support for extrapolation based on inhibition of C5 function to other rare disease indications approved for eculizumab RP., (© 2023. The Author(s).)

Background: Streptococcus pneumoniae-associated hemolytic uremic syndrome (P-HUS) is a rare and severe disease. Only a few reports have been published about eculizumab use in P-HUS., Methods: We analyzed demographic, clinical, and laboratory data of patients with P-HUS from our center., Results: The cohort consisted of 4 females and 3 males. All patients had pneumonia. Four were given eculizumab (days 1-3). The eculizumab group required a shorter duration of dialysis and mechanical ventilation (medians 20 vs. 28.5 and 30 vs 38.5 days, respectively) compared with the non-eculizumab group, but this was still much longer than normally reported; the thrombocytopenia resolution was similar in both groups (medians 10 vs. 8 days). Chronic kidney disease (CKD) was correlated with the duration of dialysis and mechanical ventilation duration at 1 year (r = 0.797, P = 0.032 and r = 0.765, P = 0.045) and last follow-up (r = 0.807, P = 0.028 and r = 0.814, P = 0.026, respectively); our scoring system showed even stronger correlations (r = 0.872, P = 0.011 and r = 0.901, P = 0.0057, respectively). The eculizumab group showed slightly better 1-year and last follow-up CKD stage (2.75 vs. 3, P = 0.879 and 2.5 vs. 3.67, P = 0.517)., Conclusions: Despite the fact that the eculizumab group showed better outcomes, eculizumab does not seem to improve the course of P-HUS compared with previous reports. Kidney outcomes are strongly correlated with the duration of dialysis and mechanical ventilation duration. A higher resolution version of the Graphical abstract is available as Supplementary information., (© 2023. The Author(s).)

Background: The long-term mortality of kidney transplantation patients with atypical hemolytic uremic syndrome remains high, and the efficacy of the main treatment eculizumab is still controversial., Objective: A comprehensive systematic review and meta-analysis of clinical trials using eculizumab in renal transplant patients with atypical hemolytic uremic syndrome was conducted to evaluate the efficacy of this therapy and its impact on renal function., Methods: A comprehensive systematic search was conducted across multiple reputable databases, including Ovid (MEDLINE, EMBASE), PubMed, and the Cochrane Library (since database inception), to identify relevant studies exploring the use of eculizumab in patients with atypical hemolytic uremic kidney transplantation. Various renal function parameters, such as dialysis, rejection, glomerular filtration rate, serum creatinine, lactate dehydrogenase, and platelet count, along with patient relapse rates, were extracted and summarized using a combination of robust statistical methods, including fixed effects, random effects, and general inverse variance methods., Result: Eighteen trials with 618 subjects were analyzed. Our analysis suggests that the use of eculizumab is associated with a reduced likelihood of AHUS recurrence (odds ratio (OR) = 0.05, 95% CI: 0.00-0.13), as well as a significant reduction in the need for dialysis (odds ratio (OR) = 0.13, 95% CI: 0.01-0.32). Additionally, eculizumab treatment led to lower serum creatinine levels (mean differences (MD) = 126.931μmoI/L, 95% CI: 115.572μmoI/L-138.290μmoI/L) and an improved glomerular filtration rate (mean differences (MD) = 59.571 ml/min, 95% CI: 57.876 ml/min-61.266 mL/min). Our results also indicate that the use of eculizumab reduces the likelihood of rejection (odds ratio (OR) = 0.09, 95% CI: 0.01-0.22). Furthermore, the drug was effective in improving platelet counts (×10∧9/L) (mean differences (MD) = 163.421, 95% CI: 46.998-279.844) and lactate dehydrogenase levels (mean differences (MD) = 336.608 U/L, 95% CI: 164.816 U/L-508.399 U/L)., Conclusions: Based on the meta-analysis, treatment with eculizumab can reduce dialysis rates and improve patients' quality of life by enhancing renal function.

Atypical Hemolytic Uremic Syndrome (aHUS) is a systemic disease due to dysregulation of the alternate complement pathway, mortality is estimated at 10% and more than 50% of patients progress to end-stage renal disease. The aim of this study was to summarize the clinical data and biological results as well as the evolution and management of patients with aHUS seen over a period of four years in one specialized department in Algeria. Our study was observational and longitudinal. The inclusion criteria were: the clinical-biological triad of aHUS and age ≤ 16 years. The type of treatment, the presence of complement mutation or anti-complement factor autoantibodies were not eligibility conditions. On inclusion and every six months, demographic data, clinical and biological history and results after treatment were collected prospectively. Our workforce consisted of 21 children with aHUS. Thirteen patients benefited from a complement study; among them, 7 had complement abnormalities. Eleven children had familial HUS; among them 8 died and 6 were less than one year old. Plasma exchanges were performed in two children. Six patients received eculizumab, with an average age of 3.6 years. After the acute phase, 9 children recovered their kidney function, one child had developed a chronic kidney disease (CKD), and 11 died, among them 8 belong to aHUS families. Fifty percent of deaths occurred in the first 3 months. At 2 years of evolution, out of 7 children having reached this stage, five had renal sequelae and four of them had CKD. The severe prognosis of this disease makes early diagnosis and treatment essential.

Atypical hemolytic uremic syndrome is a rare disorder with an estimated annual incidence of about two cases per million in the adult population. It is caused by the overactivation of the alternative pathway of the complement system. The disease can be triggered by many factors, including pregnancy, viral diseases, and sepsis; approximately 30% of atypical hemolytic uremic syndrome cases are caused by unknown processes. We present a case of a patient with C3-complement system mutations and aHUS triggered by the use of a new synthetic psychoactive drug., (© 2023. The Author(s) under exclusive licence to Italian Society of Nephrology.)

Historically, the majority of patients with complement-mediated atypical hemolytic uremic syndrome (CaHUS) progress to end-stage kidney disease (ESKD). Single-arm trials of eculizumab with a short follow-up suggested efficacy. We prove, for the first time to our knowledge, in a genotype matched CaHUS cohort that the 5-year cumulative estimate of ESKD-free survival improved from 39.5% in a control cohort to 85.5% in the eculizumab-treated cohort (hazard ratio, 4.95; 95% confidence interval [CI], 2.75-8.90; P = .000; number needed to treat, 2.17 [95% CI, 1.81-2.73]). The outcome of eculizumab treatment is associated with the underlying genotype. Lower serum creatinine, lower platelet count, lower blood pressure, and younger age at presentation as well as shorter time between presentation and the first dose of eculizumab were associated with estimated glomerular filtration rate >60 ml/min at 6 months in multivariate analysis. The rate of meningococcal infection in the treated cohort was 550 times greater than the background rate in the general population. The relapse rate upon eculizumab withdrawal was 1 per 9.5 person years for patients with a pathogenic mutation and 1 per 10.8 person years for those with a variant of uncertain significance. No relapses were recorded in 67.3 person years off eculizumab in those with no rare genetic variants. Eculizumab was restarted in 6 individuals with functioning kidneys in whom it had been stopped, with no individual progressing to ESKD. We demonstrated that biallelic pathogenic mutations in RNA-processing genes, including EXOSC3, encoding an essential part of the RNA exosome, cause eculizumab nonresponsive aHUS. Recessive HSD11B2 mutations causing apparent mineralocorticoid excess may also present with thrombotic microangiopathy., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Eculizumab is a C5 inhibitor approved for the treatment of paroxysmal nocturnal hemoglobinuria (PNH), atypical hemolytic uremic syndrome (aHUS), and anti-acetylcholine receptor antibody-positive generalized myasthenia gravis (AChR + gMG) in Japan. We report integrated safety data from post-marketing surveillance in these three indications, focusing on commonly occurring adverse events (AEs) and infection-related AEs. Of 1219 patients registered, 1055 (PNH: 780; aHUS: 192; AChR + gMG: 83) had available safety data. Total eculizumab exposure was 3977.361 patient-years. AEs were reported in 74.03% of patients. AEs with an incidence of  ≥ 1.0 per 100 patient-years included hemolysis, headache, nasopharyngitis, renal impairment, anemia, pneumonia, upper respiratory tract inflammation, influenza, condition aggravated, and infection. The incidence of infection-related AEs was 21.30 per 100 patient-years, the most frequent types (≥ 1.0 per 100 patient-years) being nasopharyngitis, pneumonia, influenza, and infection. Meningococcal infections were reported in four patients (0.10 per 100 patient-years). Two patients died from meningococcal sepsis, with a mortality rate of 0.05 per 100 patient-years. This is the largest safety dataset on eculizumab in Japan derived from more than 10 years of clinical experience. No new safety signals were observed and the safety profile of eculizumab was consistent with that in previous clinical trials and international real-world safety analyses., (© 2023. Japanese Society of Hematology.)

Significance Statement: Shiga toxin-related hemolytic uremic syndrome (STEC-HUS) is a serious condition, characterized by multiorgan thrombotic microangiopathy, mainly affecting children. Renal involvement is severe, with approximately half of patients requiring dialysis. So far, no specific treatment has been proven efficient in STEC-HUS. The use of eculizumab, a monoclonal antibody inhibiting terminal complement complex, has demonstrated remarkable success in atypical hemolytic uremic syndrome, but its use in uncontrolled studies to treat STEC-HUS has yielded inconsistent results. In this Phase 3 randomized, placebo-controlled trial in 100 pediatric patients with STEC-HUS, the findings did not show efficacy of eculizumab during the acute phase of the disease. However, the results indicated a reduction of renal sequelae in eculizumab-treated patients at 1-year follow-up. Larger prospective studies would be needed to further explore eculizumab as a potential treatment., Background: Shiga toxin-related hemolytic uremic syndrome (STEC-HUS) in children is a severe condition, resulting in approximately 50% of patients requiring RRT. Furthermore, at least 30% of survivors experience kidney sequelae. Recently, activation of the complement alternative pathway has been postulated as a factor in STEC-HUS pathophysiology, leading to compassionate use of eculizumab, a monoclonal antibody inhibiting the terminal complement complex, in affected patients. Given the lack of therapy for STEC-HUS, a controlled study of eculizumab efficacy in treating this condition is a priority., Methods: We conducted a Phase 3 randomized trial of eculizumab in children with STEC-HUS. Patients were randomly assigned in a 1:1 ratio to receive either eculizumab or placebo during 4 weeks. Follow-up lasted for 1 year. The primary end point was RRT duration <48 hours after randomization. Secondary endpoints included hematologic and extrarenal involvement., Results: Baseline characteristics were similar among the 100 patients who underwent randomization. The rate of RRT <48 hours did not differ significantly between the two groups (48% in the placebo versus 38% in the eculizumab group; P = 0.31) or in the course of ARF. The two groups also exhibited similar hematologic evolution and extrarenal manifestations of STEC-HUS. The proportion of patients experiencing renal sequelae at 1 year was lower in the eculizumab group than in the placebo group (43.48% and 64.44%, respectively, P = 0.04). No safety concern was reported., Conclusions: In pediatric patients with STEC-HUS, eculizumab treatment does not appear to be associated with improved renal outcome during acute phase of the disease but may reduce long-term kidney sequelae., Clinical Trials Registrations: EUDRACT (2014-001169-28) ClinicalTrials.gov ( NCT02205541 )., (Copyright © 2023 by the American Society of Nephrology.)

Aim: Ravulizumab and eculizumab are complement C5 inhibitors approved for the treatment of atypical hemolytic uremic syndrome (aHUS). Ravulizumab requires less frequent infusions than eculizumab, which may reduce treatment burden. This study investigated patients' treatment preferences and the impact of both treatments on patient and caregiver quality of life. Materials & methods: Two surveys were conducted (one for adult patients with aHUS and one for caregivers of pediatric patients with aHUS) to quantitatively assess treatment preference and the patient- and caregiver-reported impact of ravulizumab and eculizumab on quality of life. Patients were required to have a diagnosis of aHUS, to be currently receiving treatment with ravulizumab and to have received prior treatment with eculizumab. Participants were recruited via various sources: the Alexion OneSource™ patient support program, the Rare Patient Voice recruitment agency, the aHUS Foundation and directly via a clinician involved in the study. Results: In total, 50 adult patients (mean age: 46.5 years) and 16 caregivers of pediatric patients (mean age: 10.1 years) completed the surveys. Most adult patients (94.0%) and all caregivers reported an overall preference for ravulizumab over eculizumab; infusion frequency was one of the main factors for patients when selecting their preferred treatment. Fewer patients reported disruption to daily life and the ability to go to work/school due to ravulizumab infusion frequency (4.0% and 5.7%, respectively) than eculizumab infusion frequency (72.0% and 60.0%), with similar results for caregivers. Conclusion: Adult patients and caregivers of pediatric patients indicated an overall preference for ravulizumab than eculizumab for the treatment of aHUS, driven primarily by infusion frequency. This study contributes to the emerging real-world evidence on the treatment impact and preference in patients with aHUS.

Rationale & Objective: C3 glomerulopathy (C3GN) and atypical hemolytic uremic syndrome (aHUS) are 2 distinct rare kidney diseases caused by dysregulation of the alternative complement pathway. Patients with C3GN and concurrent kidney lesions of thrombotic microangiopathy (TMA) have been rarely reported. We characterized the clinical features and underlying immunological abnormalities in these patients., Study Design: Case series., Setting & Participants: Patients with C3GN and concomitant TMA lesions on biopsy registered from 2009 to 2019 in the French National Registry of C3GN., Findings: Among 278 registered patients with C3GN, 16 (6%) had biopsy-proven glomerular and/or vascular TMA lesions. Their median age at diagnosis was 39 years (range, 7-76), and 59% were female. Fourteen of the 16 patients (88%) had an estimated glomerular filtration rate of<30mL/min/1.73m 2 and 3 of 16 (19%) required dialysis. Twelve of the 14 evaluated patients (86%) showed evidence of mechanical hemolysis. Fifty percent of the patients had low C3 levels. Six of the 14 evaluated patients had a rare variant in complement genes, and 4 of the 16 patients (25%) had monoclonal gammopathy. Among the 16 patients, 10 (63%) received eculizumab, 5 (31%) received immunosuppressive therapy, and 4 (25%) received clone-targeted chemotherapy. Median kidney survival was 49 months., Limitations: Small retrospective case series with a limited number of biopsies including electron microscopy., Conclusions: Concomitant C3GN and TMA is extremely rare and is associated with poor kidney outcomes. Genetic or acquired abnormalities of the alternative complement pathway are common as is the presence of monoclonal gammopathy, which may inform the selection of treatment approaches., (Copyright © 2023 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

In the last decade, a deeper understanding of the pathogenesis of complement mediated hemolytic disorders, such as paroxysmal nocturnal hemoglobinuria (PNH), cold agglutinin disease (CAD), warm type autoimmune hemolytic anemia (AIHA) with complement activation (wAIHA), and atypical hemolytic uremic syndrome (aHUS), paved the way to the therapeutic shift from purely supportive approaches to complement-targeted therapies. This resulted in a significant improvement in disease management, survival, and quality of life. In this review, we will provide a snapshot of novel therapies for complement-mediated hemolytic anemias with a focus on those ready to use in clinical practice. C5 inhibitors eculizumab and the long-acting ravulizumab, are the established gold standard for untreated PNH patients, whilst the C3 inhibitor pegcetacoplan should be considered for suboptimal responders to anti-C5 drugs. Several additional compounds targeting the complement cascade at different levels (other C5 inhibitors, factor B and D inhibitors) are under active investigation with promising results. In CAD, immunosuppression with rituximab remains the first-line. However, recently FDA and EMA approved the anti-C1s monoclonal antibody, sutimlimab, that showed dramatic responses and whose regulatory approval is soon awaited in many countries. Other drugs under investigation in AIHA include the C3 inhibitor pegcetacoplan, and the anti-C1q ANX005 for warm AIHA with complement activation. Finally, aHUS is an indication for complement inhibitors. Eculizumab and ravulizumab have been approved, whilst other C5 inhibitors, and novel lectin pathway inhibitors are under active investigation in this disease., (© 2023 The Authors. European Journal of Haematology published by John Wiley & Sons Ltd.)

We present eight cases of the homozygous MCPggaac haplotype, which is considered to increase the likelihood and severity of atypical hemolytic uremic syndrome (aHUS), especially in combination with additional risk aHUS mutations. Complement blockade (CBT) was applied at a median age of 92 months (IQR 36-252 months). The median number of relapses before CBT initiation (Eculizumab) was two. Relapses occurred within an average of 22.16 months (median 17.5, minimum 8 months, and maximum 48 months) from the first subsequent onset of the disease (6/8 patients). All cases were treated with PI/PEX, and rarely with renal replacement therapy (RRT). When complement blockade was applied, children had no further disease relapses. Children with MCPggaac haplotype with/without additional gene mutations can achieve remission through renal replacement therapy without an immediate need for complement blockade. If relapse of aHUS occurs soon after disease onset or relapses are repeated frequently, a permanent complement blockade is required. However, the duration of such a blockade remains uncertain. If complement inhibition is not applied within 4-5 relapses, proteinuria and chronic renal failure will eventually occur.

Introduction Eculizumab is a complement inhibitor used in treating atypical hemolytic uremic syndrome (aHUS). This study showcases patient demographics, clinical and laboratory results of these patients, and overall outcomes of patients with aHUS treated with eculizumab. Methods The authors conducted a retrospective case study including 9 patients who received at least 1 dose of eculizumab for treating aHUS. A linear mixed effects model was used with random effects for each patient and fixed effects for eculizumab and time since admission. A p value < 0.05 was significant. Results Nine patients were treated with eculizumab for aHUS. Most patients were Black (n = 5) with either Medicare or Medicaid (n = 5). Genetic mutations were tested for in 5 patients. There were significant decreases in lactate dehydrogenase (LD, p = 0.029) and creatinine (Cr, p = 0.012) when on treatment. No significance was found in hemoglobin (p = 0.258) or platelets (p = 0.569). Treatment was stopped in 7 patients, of which 3 had no evidence of disease relapse. The only adverse event was severe thrombocytopenia (n = 1). Discussion This multicase study is the first of its kind in which most patients are Black, showing that there is a lack of research of this kind, especially on genetic mutations. Most of our patients did not have private insurance or had Medicaid/Medicare. There was a 246.5-day median duration of treatment. There was low risk of adverse events. Conclusion This case series elucidates the effective use of eculizumab for atypical hemolytic uremic syndromein a diverse patient population and emphasizes the need for more research in this area., Competing Interests: Conflicts of InterestNone declared

Introduction: Eculizumab is a monoclonal antibody that binds to complement protein C5, inhibiting complement-mediated thrombotic microangiopathy. It is approved for several indications including atypical hemolytic uremic syndrome. Additionally, eculizumab is used off-label for antibody-mediated rejection and C3 glomerulopathy in renal transplant recipients. Due to limited data available, the purpose of this study was to describe the use of eculizumab treatment in renal transplant recipients. Design: This retrospective single-center study evaluated the safety and efficacy of eculizumab for on- and off-label indications in renal transplant recipients. Adult renal transplant recipients receiving at least 1 dose of eculizumab posttransplant between October 2018 and September 2021 were included. The primary outcome evaluated was graft failure in patients treated with eculizumab. Results: Forty-seven patients were included in analysis. The median age at eculizumab initiation was 51 years [IQR 38-60], with 55% being female. Indications for eculizumab included atypical hemolytic uremic syndrome/thrombotic microangiopathy (63.8%), antibody-mediated rejection (27.7%), C3 glomerulopathy (4.3%), and other (4.3%). Graft failure occurred in 10 patients (21.3%) with a median of 2.4 weeks [IQR 0.5-23.3] from transplant to graft failure. At last follow-up (median 56.1 weeks), 44 (93.6%) patients were alive. After eculizumab initiation, renal function improved at 1 week, 1 month, and last follow-up. Conclusion: Eculizumab treatment demonstrated a benefit on graft and patient survival compared to reported incidence in thrombotic microangiopathy and antibody-mediated rejection. Due to the small sample size and retrospective design, further research is warranted to confirm these results.

Background: Eculizumab is a monoclonal antibody for the treatment of atypical hemolytic uremic syndrome (aHUS). Kidney damage, a common condition in patients with aHUS, may result in proteinuria. Because proteinuria may affect the pharmacokinetics of therapeutic proteins such as eculizumab, the aim of our study was to investigate the effect of proteinuria on eculizumab pharmacokinetics., Methods: This study was an ancillary study of a previously performed pharmacokinetic-pharmacodynamic study of eculizumab in aHUS. Proteinuria, measured as urinary protein-creatinine ratios (UPCR), was investigated as covariate for eculizumab clearance. Thereafter, we evaluated the effect of proteinuria on the exposure to eculizumab in a simulation study for the initial phase and for a 2-weekly and 3-weekly interval in the maintenance phase., Results: The addition of UPCR as a linear covariate on clearance to our base model resulted in a statistically improved fit ( P < 0.001) and reduction of unexplained variability in clearance. From our data, we predicted that in the initial phase, 16% of the adult patients with severe proteinuria (UPCR >3.1 g/g) will have inadequate complement inhibition (classical pathway activity >10%) on day 7 of treatment, compared with 3% of the adult patients without proteinuria. None of the pediatric patients will have inadequate complement inhibition at day 7 of treatment. For the 2- and 3-weekly dosing intervals, we predicted that, respectively, 18% and 49% of the adult patients and, respectively, 19% and 57% of the pediatric patients with persistent severe proteinuria will have inadequate complement inhibition, compared with, respectively, 2% and 13% of the adult patients and, respectively, 4% and 22% of the pediatric patients without proteinuria., Conclusions: Severe proteinuria is associated with a higher risk of underexposure to eculizumab., Clinical Trial Registry Name and Registration Number: CUREiHUS, Dutch Trial Register, NTR5988/NL5833., (Copyright © 2023 by the American Society of Nephrology.)

Background: We present this challenging case report of Atypical Haemolytic Uremic Syndrome (aHUS) presenting with multi-organ involvement in a patient and heterozygous CFHR1/CFHR3 gene variant, which was refractory to initial eculizumab therapy., Case Presentation: A forty-three year old female presented with aHUS and had heterozygous disease-associated deletions in the complement genes CFHR1/CFHR3. She had progressive kidney failure and severe extra-renal manifestations including cardiomyopathy and haemorrhagic cystitis; as well as pulmonary, gastrointestinal and neurological involvement. The initial kidney biopsy revealed thrombotic microangiopathy (TMA) changes involving all glomeruli. Clinical improvement was initially seen during eculizumab initiation with suppressed CH50 level, but a new rhinovirus/enterovirus upper respiratory tract infection triggered further severe multi-organ disease activity. The extra-renal manifestations stabilised, then ultimately improved after a period of eculizumab dose intensification. However, the impact on dose intensification on this improvement is unclear. Despite the extra-renal clinical improvement, she ultimately progressed to end-stage kidney disease (ESKD), commencing peritoneal dialysis for three years before undergoing a successful uncomplicated cadaveric kidney transplant without prophylactic eculizumab. Two years after transplant, she has excellent transplant graft function without any further disease recurrence., Conclusions: This case highlights the concept of extra-renal manifestations in aHUS initially resistant to eculizumab, which potentially responded to dose intensification. Whilst organ injuries are potentially reversible with timely targeted treatment, it appears that the kidneys are most vulnerable to injury., (© 2023. Crown.)

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS) are two rare and severe conditions caused by chronic complement (C') system dysregulation. Treatment with eculizumab, a recombinant, humanized monoclonal antibody against complement C5, changed the natural history of both diseases inducing remission and improving patient outcome. Ravulizumab, a new long-acting next-generation C5 inhibitor, has been recently approved for treatment of PNH and aHUS., Areas Covered: Main characteristics of ravulizumab are described: composition, dosing, efficacy and safety profile. Further, an overview of seminal studies and clinical trials using ravulizumab to treat PNH and aHUS in children and adults is detailed. Literature review was performed using the following key words: paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, and ravulizumab., Expert Opinion: Ravulizumab profile to treat PNH and aHUS is equivalent to eculizumab in efficacy and safety but allows extended dosing interval to every 4-8 weeks based on patient weight, and requires reduced infusion time. Less travels to infusion centers and medical visits and decreasing job and school absences significantly increase patient and families' QoL, while reducing cost. Further infusion time is reduced. Ravulizumab will possibly become the treatment of choice for patients with PNH and aHUS on chronic C5 inhibition.

Background: Atypical Haemolytic Uremic Syndrome is an acute life-threatening condition, characterized by the clinical triad of microangiopathic hemolytic anaemia, thrombocytopenia, kidney injury. Management of pregnants affected by Atypical Haemolytic Uremic Syndrome can be a serious concern for obstetric anesthesiologist in the delivery room and in the intensive care unit., Case Presentation: A 35-year-old primigravida with a monochorionic diamniotic twin pregnancy, presented with an acute haemorrhage due to retained placenta after elective caesarean section and underwent surgical exploration. In the postoperative period, the patient progressively developed hypoxemic respiratory failure and, later on, anaemia, severe thrombocytopenia, and acute kidney injury. A timely diagnosis of Atypical Haemolytic Uremic Syndrome was made. Non-invasive ventilation and high-flow nasal cannula oxygen therapy sessions were initially required. Hypertensive crisis and fluid overload were aggressively treated with a combination of beta and alpha adrenergic blockers (labetalol 0,3 mg/kg/h by continuous intravenous infusion for the first 24 hours, bisoprolol 2,5 mg twice daily for the first 48 hours, doxazosin 2 mg twice daily), central sympatholytics (methyldopa 250 mg twice daily for the first 72 hours, transdermal clonidine 5 mg by the third day), diuretics (furosemide 20 mg three times daily), calcium antagonists (amlodipine 5 mg twice daily). Eculizumab 900 mg was administered via intravenous infusion once per week, attaining hematological and renal remissions. The patient also received several blood transfusion units and anti- meningococcal B, anti-pneumococcal, anti-haemophilus influenzae type B vaccination. Her clinical condition progressively improved, and she was finally discharged from intensive care unit 5 days after admission., Conclusions: The clinical course of this report underlines how crucial it is for the obstetric anaesthesiologist to promptly identify Atypical Haemolytic Uremic Syndrome, since early initiation of eculizumab, together with supportive therapy, has a direct effect on patient outcome., (© 2023. The Author(s).)

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., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Eculizumab is a lifesaving yet expensive drug for atypical haemolytic uraemic syndrome (aHUS). Current guidelines advise a fixed-dosing schedule, which can be suboptimal and inflexible in the individual patient., Methods: We evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) [classical pathway (CP) activity levels] of eculizumab in 48 patients, consisting of 849 time-concentration data and 569 CP activity levels. PK-PD modelling was performed with non-linear mixed-effects modelling. The final model was used to develop improved dosing strategies., Results: A PK model with parallel linear and non-linear elimination rates best described the data with the parameter estimates clearance 0.163 L/day, volume of distribution 6.42 L, maximal rate 29.6 mg/day and concentration for 50% of maximum rate 37.9 mg/L. The PK-PD relation between eculizumab concentration and CP activity was described using an inhibitory Emax model with the parameter estimates baseline 101%, maximal inhibitory effect 95.9%, concentration for 50% inhibition 22.0 mg/L and  Hill coefficient 5.42. A weight-based loading dose, followed by PK-guided dosing was found to improve treatment. On day 7, we predict 99.95% of the patients to reach the efficacy target (CP activity <10%), compared with 94.75% with standard dosing. Comparable efficacy was predicted during the maintenance phase, while the dosing interval could be prolonged in ∼33% of the population by means of individualized dosing. With a fixed-dose 4-week dosing interval to allow for holidays, treatment costs will increase by 7.1% and we predict 91% of the patients will reach the efficacy target., Conclusions: A patient-friendly individualized dosing strategy of eculizumab has the potential to improve treatment response at reduced costs., (© The Author(s) 2022. Published by Oxford University Press on behalf of ERA.)

Background: Eculizumab was approved for atypical haemolytic uraemic syndrome (aHUS) in Japan in 2013. Post-marketing surveillance (PMS) was mandated by regulatory authorities to assess the safety and effectiveness of eculizumab in patients with aHUS in a real-world setting., Methods: Paediatric patients in the PMS cohort who were <18 years of age at the first administration of eculizumab and diagnosed with aHUS [excluding Shiga toxin-producing Escherichia coli HUS, thrombotic thrombocytopaenic purpura and secondary thrombotic microangiopathy (TMA)] were included in the effectiveness and safety analysis. Clinical endpoints of effectiveness [complete TMA response, TMA event-free status, platelet (PLT) count and lactate dehydrogenase (LDH) normalization, serum creatinine (sCr) decrease and estimated glomerular filtration rate (eGFR) improvement] were analysed in patients treated with at least one dose of eculizumab. Serious adverse events (SAEs) were also evaluated., Results: A total of 40 paediatric patients (median age 5 years) were included. The median eculizumab treatment duration was 66 weeks. PLT count, LDH and eGFR significantly improved at 10 days post-treatment. Complete TMA response, haematologic normalization, sCr decrease, eGFR improvement and TMA event-free status were achieved by 73.3%, 73.3%, 70.0%, 78.3% and 77.5% of patients, respectively. Discontinuation criteria were met by 18 patients: 13 patients maintained treatment discontinuation at the end of observation and 5 patients, including 1 patient with aHUS relapse, continued the treatment but extended the treatment interval. During eculizumab treatment, 59 SAEs (0.66/person-year) were reported. Although four deaths were reported, none of them were related to eculizumab., Conclusion: Eculizumab was well tolerated and effective for paediatric patients with aHUS in the real-world setting in Japan., (© The Author(s) 2022. Published by Oxford University Press on behalf of the ERA.)

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., (© 2022. The Author(s), under exclusive licence to The Japanese Society of Nephrology.)

Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare disease that manifests with microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure, and is associated with dysregulation of the alternative complement pathway. The chromosomal region including CFH and CFHR1-5 is rich in repeated sequences, favoring genomic rearrangements that have been reported in several patients with aHUS. However, there are limited data on the prevalence of uncommon CFH-CFHR genomic rearrangements in aHUS and their impact on disease onset and outcomes., Methods: In this study, we report the results of CFH-CFHR Copy Number Variation (CNV) analysis and the characterization of resulting structural variants (SVs) in a large cohort of patients, including 258 patients with primary aHUS and 92 with secondary forms., Results: We found uncommon SVs in 8% of patients with primary aHUS: 70% carried rearrangements involving CFH alone or CFH and CFHR (group A; n=14), while 30% exhibited rearrangements including only CFHRs (group B; n=6). In group A, 6 patients presented CFH::CFHR1 hybrid genes, 7 patients carried duplications in the CFH-CFHR region that resulted either in the substitution of the last CFHR1 exon(s) with those of CFH ( CFHR1::CFH reverse hybrid gene) or in an internal CFH duplication. In group A, the large majority of aHUS acute episodes not treated with eculizumab (12/13) resulted in chronic ESRD; in contrast, anti-complement therapy induced remission in 4/4 acute episodes. aHUS relapse occurred in 6/7 grafts without eculizumab prophylaxis and in 0/3 grafts with eculizumab prophylaxis. In group B, 5 subjects had the CFHR3 1-5 ::CFHR4 10 hybrid gene and one had 4 copies of CFHR1 and CFHR4 . Compared with group A, patients in group B exhibited a higher prevalence of additional complement abnormalities and earlier disease onset. However, 4/6 patients in this group underwent complete remission without eculizumab treatment. In secondary forms we identified uncommon SVs in 2 out of 92 patients: the CFHR3 1-5 ::CFHR4 10 hybrid and a new internal duplication of CFH ., Discussion: In conclusion, these data highlight that uncommon CFH-CFHR SVs are frequent in primary aHUS and quite rare in secondary forms. Notably, genomic rearrangements involving the CFH are associated with a poor prognosis but carriers respond to anti-complement therapy., Competing Interests: MN has received honoraria from Alexion Pharmaceuticals for giving lectures, and for participating in advisory boards, and she has received research grants from Omeros, Gemini, Novartis and BioCryst Pharmaceuticals. AB has received honoraria from Alexion Phamaceuticals and BioCryst Pharmaceuticals. GR has consultancy agreements with AbbVie, Alexion Pharmaceuticals, Novartis Pharma and BioCryst Pharmaceuticals. Since 1st May 2022, the co-author EV has been employed by Frontiers Media SA. EV declared her affiliation with Frontiers, and the handling Editor states that the process nevertheless met the standards of a fair and objective review. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest., (Copyright © 2023 Piras, Valoti, Alberti, Bresin, Mele, Breno, Liguori, Donadelli, Rigoldi, Benigni, Remuzzi and Noris.)

BACKGROUND Complement-mediated thrombotic microangiopathy (cTMA), is a genetic disease that results when an unchecked alternative complement pathway is triggered by an external factor, resulting in endothelial cell injury with microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure, though other organ systems may be involved. CASE REPORT A 5-year-old girl presented with non-bloody diarrhea, hemolysis, renal failure, and thrombocytopenia. She was negative for Shiga toxin. She was diagnosed with cTMA, and this diagnosis was confirmed later by a mutation in the complement factor H (CFH) gene. The patient was started on eculizumab 8 weeks after onset of symptoms. A month later, she was able to stop hemodialysis. Eculizumab was given for a year, and then, because of clinical remission, was stopped. At the time of stopping hemodialysis, serum creatinine was 2.07 mg/dL; at the end of eculizumab therapy, it was 1.23 mg/dL. Now, 10 years later, it is 1.10 mg/dL. Glomerular filtration rate by Schwartz equation was 52 mL/min/1.73 m² after eculizumab and 60 mL/min/1.73 m² currently. The cTMA lab parameters normalized after 2 doses of eculizumab and have remained normal for 10 years. Two years ago, on routine ultrasound, renal cysts were noted. Recent genetic testing re-confirmed the CFH mutation and additionally showed a polycystic kidney disease (PKD1) mutation. Notably, there is no family history of either. Currently, the patient has mild proteinuria. CONCLUSIONS Instead of lifelong eculizumab treatment, we successfully managed the patient's condition with a year of eculizumab and intensive followup on sixty occasions over a decade. This approach can work if there are no relapses. Genetic tests revealed mutations for cTMA and autosomal dominant polycystic kidney disease (ADPKD)/PKD1 in the same patient. These have not been reported before, to the best of our knowledge.