Complement dysregulation associated with a genetic variant in factor H-related protein 5 in atypical hemolytic uremic syndrome

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) can be associated with mutations, deletions, or hybrid genes in factor H-related (FHR) proteins.

METHODS

A child with aHUS was investigated. Genetics was assessed by Sanger and next generation sequencing. Serum FHR5 was evaluated by immunoblotting, ELISA, and by induction of rabbit red blood cell hemolysis in the presence/absence of recombinant human rFHR5. Mutagenesis was performed in HEK cells.

RESULTS

A heterozygous genetic variant in factor H-related protein 5 (CFHR5), M514R, was found in the child, who also had a homozygous deletion of CFHR3/CFHR1, and antibodies to factor H, as well as low levels of C3. Patient serum exhibited low levels of FHR5. In the presence of rabbit red blood cells, patient serum induced hemolysis which decreased when rFHR5 was added at physiological concentrations. Similar results were obtained using serum from the father, bearing the CFHR5 variant without factor H antibodies. Patient FHR5 formed normal dimers. The CFHR5 M514R variant was expressed in HEK cells and minimal secretion was detected whereas the protein level was elevated in cell lysates.

CONCLUSIONS

Decreased secretion of the product of the mutant allele could explain the low FHR5 levels in patient serum. Reduced hemolysis when rFHR5 was added to serum suggests a regulatory role regarding complement activation on red blood cells. As such, low levels of FHR5, as demonstrated in the patient, may contribute to complement activation.

Clinical characteristics of anti-GBM disease with thrombotic microangiopathy: a case report and literature review

The coexistence of anti-glomerular basement membrane (anti-GBM) disease with thrombotic microangiopathy (TMA) is rarely encountered, and the clinical characteristics of this phenomenon are not well known.A 76-year-old Japanese woman with a history of idiopathic pulmonary disease was diagnosed with anti-GBM disease due to rapidly progressive glomerulonephritis and a positive anti-GBM antibody test result. We treated the patient with hemodialysis, glucocorticoids, and plasmapheresis. During treatment, the patient suddenly became comatose. TMA was then diagnosed because of thrombocytopenia and microangiopathic hemolytic anemia. The activity of a disintegrin-like and metalloproteinase with thrombospondin type 1 motif 13 (ADAMTS-13) was retained at 48%. Although we continued the treatment, the patient died of respiratory failure. An autopsy revealed the cause of respiratory failure to be an acute exacerbation of interstitial pneumonia. The clinical findings of the renal specimen indicated anti-GBM disease; however, there were no lesions suggestive of TMA. A genetic test did not reveal an apparent genetic mutation of the atypical hemolytic uremic syndrome.We conducted a literature review of past case reports of anti-GBM disease with TMA. The following clinical characteristics were obtained. First, 75% of the cases were reported in Asia. Second, TMA tended to appear during the treatment course for anti-GBM disease and usually resolved within 12 weeks. Third, ADAMTS-13 activity was retained above 10% in 90% of the cases. Fourth, central nervous system manifestations occurred in more than half of the patients. Fifth, the renal outcome was very poor. Further studies are required to understand the pathophysiology of this phenomenon.

Biallelic mutations in the CFHR genes underlying atypical hemolytic uremic syndrome in a patient with catastrophic adult-onset Still's disease and recurrent macrophage activation syndrome: A case report

We report the fatal case of a 20-year-old woman with refractory adult-onset Still's disease (AOSD) accompanied by fulminant macrophage activation syndrome (MAS) and atypical hemolytic uremic syndrome (aHUS). Anakinra and tocilizumab temporarily controlled AOSD. In 2021, she presented to ICU with generalized tonic-clonic seizure, lymphocytic aseptic meningitis, and acute kidney injury. Despite hemodialysis and methylprednisolone, she developed another seizure, MAS, and disseminated intravascular coagulation (DIC). Following brief control, MAS flares -reflected by increased plasma CXCL9 and CXCL10- re-emerged and were controlled through dexamethasone, etoposide, cyclosporin and tofacitinib. No mutations were detected in haemophagocytic lymphohistiocytosis (HLH)-associated genes, nor in genes associated with periodic fever syndromes. Post-mortem genetic testing revealed loss-of-function biallelic deletions in complement factor H-related proteins (CFHR) genes, predisposing aHUS. This case underscores the importance of prompt genetic assessment of complement-encoding alleles, in addition to HLH-related genes, in patients with severe AOSD with recurrent MAS and features of thrombotic microangiopathy (TMA).

Functional similarity of ABP 959 and eculizumab in simulated serum models of aHUS and NMOSD

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.

A comprehensive model for assessing and classifying patients with thrombotic microangiopathy: the TMA-INSIGHT score

BACKGROUND

Thrombotic Microangiopathy (TMA) is a syndrome characterized by the presence of anemia, thrombocytopenia and organ damage and has multiple etiologies. The primary aim is to develop an algorithm to classify TMA (TMA-INSIGHT score).

METHODS

This was a single-center retrospective cohort study including hospitalized patients with TMA at a single center. We included all consecutive patients diagnosed with TMA between 2012 and 2021. TMA was defined based on the presence of anemia (hemoglobin level < 10 g/dL) and thrombocytopenia (platelet count < 150,000/µL), signs of hemolysis, and organ damage. We classified patients in eight categories: infections; Malignant Hypertension; Transplant; Malignancy; Pregnancy; Thrombotic Thrombocytopenic Purpura (TTP); Shiga toxin-mediated hemolytic uremic syndrome (STEC-SHU) and Complement Mediated TMA (aHUS). We fitted a model to classify patients using clinical characteristics, biochemical exams, and mean arterial pressure at presentation.

RESULTS

We retrospectively retrieved TMA phenotypes using automatic strategies in electronic health records in almost 10 years (n = 2407). Secondary TMA was found in 97.5% of the patients. Primary TMA was found in 2.47% of the patients (TTP and aHUS). The best model was LightGBM with accuracy of 0.979, and multiclass ROC-AUC of 0.966. The predictions had higher accuracy in most TMA classes, although the confidence was lower in aHUS and STEC-HUS cases.

CONCLUSION

Secondary conditions were the most common etiologies of TMA. We retrieved comorbidities, associated conditions, and mean arterial pressure to fit a model to predict TMA and define TMA phenotypic characteristics. This is the first multiclass model to predict TMA including primary and secondary conditions.

Real-world safety profile of eculizumab in patients with paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome, or generalized myasthenia gravis: an integrated analysis of post-marketing surveillance in Japan

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.

Immune responses and safety of COVID-19 vaccination in atypical hemolytic uremic syndrome patients in Taiwan

Atypical hemolytic uremic syndrome is a rare, life-threatening disorder which can be triggered by COVID 19 infection and COVID 19 vaccination then induce multiple organ failure. Our study is the first to evaluate immune responses to COVID-19 vaccination and safety in a cohort of patients in a local single-center study in Taiwan.. Results indicate that vaccines effectively shield aHUS patients from severe COVID-19 complications without significant safety concerns. A double booster dose for the third vaccine is essential for optimal efficacy. Anti-complement therapy did not influence vaccination effectiveness. Transplant aHUS patients had the lowest immune response titers, indicating a need for additional vaccine doses. Compared to healthcare workers, aHUS patients had poor T-cell responses. We noted a superior trend with mixed-type COVID-19 vaccinations in aHUS patients, while fixed-type mRNA demonstrated better results in healthcare workers. Our findings endorse COVID-19 vaccination as a potent strategy to safeguard aHUS patients from severe complications, emphasizing the importance of vigilant monitoring pre- and post-vaccination.

Complement Factor I Gene Variant in an Atypical Hemolytic Uremic Syndrome Triggered by Hypereosinophilia Syndrome

Atypical hemolytic uremic syndrome (aHUS) is a condition characterized by acute kidney injury (AKI), thrombocytopenia, and microangiopathic hemolytic anemia secondary to complement pathway dysregulation. Several triggers have been identified as causing aHUS in genetically susceptible patients; however, hypereosinophilia syndrome (HES)-triggered aHUS has not been reported. In this article, we present a case of aHUS presented with generalized urticarial rashes and angioedema. The initial investigations revealed hypereosinophilia (maximal absolute eosinophil count of 6,840 cells/µL) with normal bone-marrow analyses; hence, idiopathic HES was diagnosed. During hospitalization, the patient developed convulsion, stuporous, and full-blown thrombotic microangiopathy (TMA), with AKI requiring temporary hemodialysis. A kidney biopsy confirmed the existence of renal TMA. Next-generation sequencing of the coding regions of aHUS-related genes was performed, revealing an underlying complement factor I (CFI) deficiency, a heterozygous variant p.P64L of CFI gene. The patient was successfully treated with high-dose steroids and extended duration of plasmapheresis.

Ischemic cerebrovascular complications with initial presentation of genetic atypical hemolytic uremic syndrome

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is a rare disease, with scarce reports of neurologic manifestations in the acute setting. Ischemic cortical infarcts concurrently with aHUS presentation have not been described in adult patients.

CASE DESCRIPTION

A 46-year-old male presented with acutely declining mental status and progressive weakness, in the setting of longstanding hypertension and known type B aortic dissection. Urgent neuroimaging showed bilateral multifocal multiterritorial ischemic infarcts, concerning for an embolic source or hypercoagulable state. Systemic workup was notable for microangiopathic hemolytic anemia and acute kidney injury. Empiric plasmapheresis was initiated for presumed thrombotic thrombocytopenic purpura. Broad workup did not support such a diagnosis, and kidney biopsy showed findings compatible with aHUS. Additional blood testing showed increased complement pathway activity. Shiga toxin was negative, and overall clinical picture fit with aHUS as diagnosis. Treatment with complement inhibitor was started and patient gradually recovered. Genetic testing confirmed a pertinent pathogenic mutation, CFHR1 homozygous deletion.

CONCLUSION

Acute multifocal multiterritorial ischemic infarcts and systemic thrombotic microangiopathy may be a manifestation of aHUS, and with associated genetic mutation, even in adult population.

Diagnosis of Bone Marrow Necrosis following Severe Vaso-Occlusive Crisis in Patient with Compound Heterozygous Sickle Cell Disease

Introduction

Bone marrow necrosis is a rare entity that can develop in context of a sickle cell disease vaso-occlusive crisis. Its physiopathology is related to an endothelial dysfunction taking place in bone marrow microvasculature.

Case Presentation

A 30-year-old patient with history of compound heterozygous sickle cell disease was admitted following SARS-CoV-2 infection with fever and diarrhea. After initial favorable evolution, he developed a severe vaso-occlusive crisis with intense hemolysis and multi-organ ischemic complications. Patient then developed high fever and hypoxemia. With the suspicion of acute thoracic syndrome, a red blood cell exchange was performed. Respiratory symptoms ceased but patient persisted febrile with very high levels of acute phase reactants, persistent pancytopenia, and leucoerythroblastic reaction. An infectious cause was ruled out. Afterward, bone marrow aspiration and bone marrow biopsy showed a picture of bone marrow necrosis, which is an extremely rare complication of vaso-occlusive crisis but, paradoxically, more frequent in milder heterozygote cases of sickle cell disease. Ultimately, large deposits of complement membrane attack complex (particles C5b-9) were demonstrated after incubation of laboratory endothelial cells with activated plasma from the patient.

Discussion

The clinical presentation and findings are consistent with a case of bone marrow necrosis. In this setting, the demonstration of complement as a potential cause of the endothelial dysfunction mimics the pattern of atypical hemolytic uremic syndrome and other microangiopathic anemias. This dysregulation may be a potential therapeutic target for new complement activation blockers.

Genotypic analysis of a large cohort of patients with suspected atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. Complement and coagulation gene variants have been associated with aHUS susceptibility. We assessed the diagnostic yield of a next-generation sequencing (NGS) panel in a large cohort of Canadian patients with suspected aHUS. Molecular testing was performed on peripheral blood DNA samples from 167 patients, collected between May 2019 and December 2021, using a clinically validated NGS pipeline. Coding exons with 20 base pairs of flanking intronic regions for 21 aHUS-associated or candidate genes were enriched using a custom hybridization protocol. All sequence and copy number variants were assessed and classified following American College of Medical Genetics guidelines. Molecular diagnostic results were reported for four variants in three individuals (1.8%). Twenty-seven variants of unknown significance were identified in 25 (15%) patients, and 34 unique variants in candidate genes were identified in 28 individuals. An illustrative patient case describing two genetic alterations in complement genes is presented, highlighting that variable expressivity and incomplete penetrance must be considered when interpreting genetic data in patients with complement-mediated disease, alongside the potential additive effects of genetic variants on aHUS pathophysiology. In this cohort of patients with suspected aHUS, using clinical pipelines for genetic testing and variant classification, pathogenic/likely pathogenic variants occurred in a very small percentage of patients. Our results highlight the ongoing challenges in variant classification following NGS panel testing in patients with suspected aHUS, alongside the need for clear testing guidance in the clinical setting. KEY MESSAGES: • Clinical molecular testing for disease associated genes in aHUS is challenging. • Challenges include patient selection criteria, test validation, and interpretation. • Most variants were of uncertain significance (31.7% of patients; VUS + candidates). • Their clinical significance may be elucidated as more evidence becomes available.  • Low molecular diagnostic rate (1.8%), perhaps due to strict classification criteria. • Case study identified two likely pathogenic variants; one each in MCP/CD46 and CFI.

The nailfold dermoscopy findings of patients with atypical haemolytic uremic syndrome

INTRODUCTION

Hemolytic uremic syndrome (HUS) is a severe disease characterized by microangiopathic anemia, thrombocytopenia, and acute renal failure.

OBJECTIVES

Atypical HUS (aHUS) that results due to genetic disorders of the alternative complement pathway results in inflammation, endothelial damage, and kidney injury. Therefore, simple and non-invasive tests are needed to evaluate the activity of the disease by assessing the microvascular structure in aHUS.

METHODS

A dermoscope (×10) is an inexpensive and easily portable device used to visualize nailfold capillaries and has high clinical performance and interobserver reliability. In this study, the nailfold capillaries of patients with aHUS who were in remission under eculizumab treatment were examined, and the findings were compared to those of a healthy control group to evaluate disease characteristics.

RESULTS

All children with aHUS had decreased capillary densities even if they were in remission. This may be indicative of ongoing inflammation and microvascular damage in aHUS.

CONCLUSION

A dermoscopy can be used as a screening tool for disease activity in patients with aHUS.

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

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

Application of a scoring system in Japanese patients diagnosed with atypical hemolytic uremic syndrome to assess the relationship between the score and clinical responses to eculizumab

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is caused by complement dysregulation and is generally diagnosed by exclusion from other disorders of thrombotic microangiopathy (TMA). Eculizumab, a terminal complement inhibitor, has been approved for aHUS treatment since 2013 in Japan. Recently, a scoring system was published to support diagnosis of aHUS. Herein we modified this scoring system to apply it to patients diagnosed with aHUS and treated with eculizumab, and assessed the association between the score and clinical responses to eculizumab.

METHODS

One hundred eighty-eight Japanese patients who were clinically diagnosed with aHUS, treated with eculizumab, and enrolled in post-marketing surveillance (PMS) were included in this analysis. Some of parameters in the original scoring system were replaced with clinically similar parameters collected in the PMS to modify the system, hereafter referred to as the TMA/aHUS score, which ranges from -15 to 20 points. Treatment responses within 90 days after eculizumab initiation were also assessed, and the relationship between treatment response and TMA/aHUS scores calculated at TMA onset was explored.

RESULTS

The median (range) TMA/aHUS score was 10 (3-16). Receiver operating characteristic curve analysis showed that the cutoff value of TMA/aHUS score to predict treatment response to eculizumab was estimated as 10, and negative predictive value indicated that ≥ 5 points was appropriate to consider assessing the treatment response to eculizumab; 185 (98%) patients had ≥ 5 points and 3 (2%) had < 5 points. Among the patients with ≥ 5 points, 96.1% showed partial response and 31.1% showed complete response. One of the three patients with < 5 points met partial response criteria. No significant difference in the TMA/aHUS scores was observed between survivors and non-survivors, suggesting that the score was not appropriate to predict the outcome (i.e., survival/death) in patients treated with eculizumab.

CONCLUSION

Almost all patients clinically diagnosed with aHUS scored ≥ 5 points and responded to eculizumab. The TMA/aHUS score system could become a supporting tool for the clinical diagnosis of aHUS and probability of response to treatment with a C5 inhibitor.

TRIAL REGISTRATION

This study was conducted as per good PMS practice guidelines for drugs (MHLW Ministerial Ordinance No. 171 of 2004).

Propensity score-matched analysis of long-term outcomes for living kidney donation in alternative complement pathway diseases: a pilot study

BACKGROUND

Atypical hemolytic syndrome (aHUS) and C3 glomerulopathy (C3G) are complement-mediated rare diseases with excessive activation of the alternative pathway. Data to guide the evaluation of living-donor candidates for aHUS and C3G are very limited. The outcomes of living donors to recipients with aHUS and C3G (Complement disease-living donor group) were compared with a control group to improve our understanding of the clinical course and outcomes of living donation in this context.

METHODS

Complement disease-living donor group [n = 28; aHUS(53.6%), C3G(46.4%)] and propensity score-matched control-living donor group (n = 28) were retrospectively identified from 4 centers (2003-2021) and followed for major cardiac events (MACE), de novo hypertension, thrombotic microangiopathy (TMA), cancer, death, estimated glomerular filtration rate (eGFR) and proteinuria after donation.

RESULTS

None of the donors for recipients with complement-related kidney diseases experienced MACE or TMA whereas two donors in the control group developed MACE (7.1%) after 8 (IQR, 2.6-12.8) years (p = 0.15). New-onset hypertension was similar between complement disease and control donor groups (21.4% vs 25%, respectively, p = 0.75). There were no differences between study groups regarding last eGFR and proteinuria levels (p = 0.11 and p = 0.70, respectively). One related donor for a recipient with complement-related kidney disease developed gastric cancer and another related donor developed a brain tumor and died in the 4th year after donation (2, 7.1% vs none, p = 0.15). No recipient had donor-specific human leukocyte antigen antibodies at the time of transplantation. Median follow-up period of transplant recipients was 5 years (IQR, 3-7). Eleven (39.3%) recipients [aHUS (n = 3) and C3G (n = 8)] lost their allografts during the follow-up period. Causes of allograft loss were chronic antibody-mediated rejection in 6 recipients and recurrence of C3G in 5. Last serum creatinine and last eGFR of the remaining patients on follow up were 1.03 ± 038 mg/dL and 73.2 ± 19.9 m/min/1.73 m2 for aHUS patients and 1.30 ± 0.23 mg/dL and 56.4 ± 5.5 m/min/1.73 m2 for C3G patients.

CONCLUSION

The present study highlights the importance and complexity of living related-donor kidney transplant for patients with complement-related kidney disorders and motivates the need for further research to determine the optimal risk-assessment for living donor candidates to recipients with aHUS and C3G.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Atypical hemolytic uremic syndrome in a patient with HIV treated with eculizumab: A case report

Thrombotic microangiopathy defines a group of pathologies characterized by microvascular dysfunction with the concurrence of microangiopathic hemolytic anemia, thrombocytopenia, and organ damage. It represents the most frequent microvascular manifestation of human immunodeficiency virus (HIV) infection. We report the case of a man in the seventh decade of life with a recent diagnosis of infection by HIV, who develops hemolytic uremic syndrome, requiring continuous renal replacement therapy and plasma replacement therapy, without response, ADAMTS13 with preserved activity, ruling out other etiologies (infectious, metabolic, and genetic) with successful response to eculizumab.

Campylobacter Colitis as a Trigger for Atypical Hemolytic Uremic Syndrome: About One Case

We present the case of a 17-year-old Caucasian male whose condition featured acute renal failure, anemia, and deep thrombocytopenia after five consecutive days of diarrhea. Campylobacter coli was identified in stool cultures and, although the direct role of this germ in the pathogenesis of hemolytic uremic syndrome (HUS) remains uncertain to this day, initial presentation was considered broadly consistent with typical HUS. However, the patient showed no signs of spontaneous recovery over time. While secondary investigations showed no abnormalities in ADAMTS13 activity or in the alternate pathway of complement, patient's condition deteriorated. Worsening kidney failure required emergency renal replacement therapy and was followed by cardiac involvement in the form of acute heart failure. Given this unfavorable development, blood samples were drawn to look for mutations in the alternate complement pathway, and eculizumab therapy was initiated without further delay, allowing prompt improvement of cardiac function and recovery of diuresis. Upon discharge, the patient still had to undergo intermittent dialysis, which would later be withdrawn. Genetic analysis ultimately confirmed the presence of a complement factor H mutation associated with a high risk of disease recurrence, indicating long-term continuation of eculizumab therapy.

Eculizumab as rescue therapy in a kidney transplant recipient with atypical hemolytic uremic syndrome: a case report

A 61-year-old female patient with chronic kidney disease due to diabetes mellitus and hypertension-induced nephropathy received a deceased donor kidney transplant in March 2020. In July 2020, she was transferred from a local hospital due to the exacerbation of general weakness and diarrhea. Upon her arrival, we noticed a high level of serum creatinine (sCr) of 1.5 mg/dL and a decrease in urine output. Her laboratory results indicated significant hemolysis, with a hemoglobin level of 7.0 g/dL, platelet count of 20 ×10³/μL, and a lactate dehydrogenase level of 3,207 IU/L. Kidney biopsy showed severe thrombotic microangiopathy without any evidence of acute rejection. Under the impression of atypical hemolytic uremic syndrome (aHUS), we immediately started plasmapheresis and hemodialysis for anuria. Eculizumab was considered as a kidney graft rescue therapy since her sCr level was not effectively decreased, and her anuria continued despite hemodialysis and plasmapheresis. Eculizumab (900 mg) was administered weekly for 4 weeks. An additional 600 mg of eculizumab was administered on the day of plasmapheresis. Since the patient's laboratory data gradually improved, hemodialysis and plasmapheresis were ceased on admission day 37. After that, eculizumab was administered biweekly (1,200 mg) two more times. The patient's sCr and platelet count normalized after 2 months of eculizumab treatment. Based on our experience, a shorter interval between the clinical diagnosis of aHUS and administration of eculizumab increases the likelihood of rescuing the kidney.

Atypical hemolytic uremic syndrome (aHUS) responsive to mycophenolate mofetil: A case report from Nepal

Introduction

An atypical hemolytic uremic syndrome is an extremely rare and life-threatening thrombotic microangiopathy. This disorder is caused by dysregulation of the alternative pathway of the complement system in association with genetic abnormalities or the development of autoantibodies. However, 30-50% of patients do not have genetic or acquired mutations in the complement system.

Case report

Patient presented with fever and periorbital swelling. She had anemia, thrombocytopenia, and deranged liver function tests. Urinalysis revealed hematuria and proteinuria. Antibody tests and genetic analysis were negative. Renal biopsy revealed findings suggestive of thrombotic microangiopathy with predominantly glomerular involvement. Thus, the diagnosis of Atypical Hemolytic Uremic Syndrome, immunofluorescence negative, genetic negative, and anti-complement negative was made.

Discussion

This article reports a case of atypical hemolytic uremic syndrome in a child with negative genetic analysis and anti-complement factor H antibody, which was treated successfully on steroid and mycophenolate mofetil. Early diagnosis along with prompt treatment and close monitoring will lead to recovery from atypical Hemolytic Uremic Syndrome.

Conclusion

Although HUS is generally associated with genetic abnormalities or a positive antibody test, some patients with HUS may present atypically with negative genetic analysis and antibody tests.

An intact zinc finger motif of the C1B domain is critical for stability and activity of diacylglycerol kinase-ε

Diacylglycerol kinase-ε (DGKε) phosphorylates DAG to phosphatidic acid with unique specificity toward 18:0/20:4 DAG (SAG). SAG is a typical backbone of phosphatidylinositol and its derivatives, therefore DGKε activity is crucial for the turnover of these signaling lipids. Malfunction of DGKε contributes to several pathophysiological conditions, including atypical hemolytic uremic syndrome (aHUS) linked with DGKE mutations. In the present study we analyzed the role of a zinc finger motif of the C1B domain of DGKε, as some aHUS-linked mutations affect this ill-defined part of the kinase. For this, we introduce a novel fluorescent assay for determination of DGKε activity which relies on the use of NBD-SAG in mixed micelles as a substrate, followed by TLC separation of NBD-phosphatidic acid formed. The assay reliably determines the activity of purified human GST-DGKε, also endogenous DGKε or overexpressed mouse DGKε-Myc in cell lysates, homogenates, and kinase immunoprecipitates. Using the above assay we found that four amino acids, Cys135, Cys138, His161 and Cys164, forming the zinc finger motif in the C1B domain are required for the DGKε-Myc activity and stability. Substitution of any of these amino acids with Ala or Trp in DGKε-Myc abolished its activity and led to its proteasomal degradation, possibly assisted by Hsp70/90/40 chaperones. Inhibition of the 26S proteasome prevented the degradation but the mutated proteins were inactive. The present data on the deleterious effect of the zinc finger motif disruption contribute to the understanding of the DGKε-linked aHUS, as the Cys164Trp substitution in mouse DGKε corresponds to the Cys167Trp one in human DGKε found in some aHUS patients.

Plasma Exchange Therapy Using Solvent Detergent-Treated Plasma: An Observational Pilot Study on Complement, Neutrophil and Endothelial Cell Activation in a Case Series of Patients Suffering from Atypical Hemolytic Uremic Syndrome

Introduction

Plasma exchange therapy (PEX) was standard treatment for thrombotic microangiopathy before eculizumab was available and is still widely applied. However, most PEX patients still ultimately progress to end-stage renal disease (ESRD). It has been suggested that infusion of plasma that contains active complement may induce additional complement activation with subsequent activation of neutrophils and endothelial cells, leading to exacerbation of organ damage and deterioration of renal function.

Objective

This observational pilot study examines the effect of hemodialysis, eculizumab and PEX before and after treatment in plasma of aHUS patients on complement-, neutrophil and endothelial cell activation.

Methods

Eleven patients were included in this pilot study. Six patients were treated with hemodialysis, 2 patients received regular infusions of eculizumab, and 3 patients were on a regular schedule for PEX. Patients were followed during 3 consecutive treatments. Blood samples were taken before and after patients received their treatment.

Results

Complement activation products increased in plasma of patients after PEX, as opposed to patients treated with hemodialysis or eculizumab. Increased levels of complement activation products were detected in omniplasma used for PEX. Additionally, activation of neutrophils and endothelial cells was observed in patients after hemodialysis and PEX, but not in patients receiving eculizumab treatment.

Conclusion

In this pilot study we observed that PEX induced complement and neutrophil activation, and that omniplasma contains significant amounts of complement activation products. Additionally, we demonstrate that hemodialysis induces activation of neutrophils and endothelial cells. Complement activation with subsequent neutrophil activation may contribute to the deterioration of organ function and may result in ESRD. Further randomized controlled studies are warranted to investigate the effect of PEX on complement- and neutrophil activation in patients with thrombotic microangiopathy.

Recurrent microangiopathic hemolysis after recovery from complement-mediated hemolytic uremia syndrome during chemotherapy for a CFH-mutated patient with T-lymphoblastic lymphoma

Complement-mediated hemolytic uremic syndrome (CM-HUS) following chemotherapy for pediatric acute lymphoid neoplasms has rarely been reported. We report the case of an 8-year-old boy with T-lymphoblastic lymphoma (T-LBL) who developed CM-HUS with complement factor H (CFH) mutations (S1191L, V1197A) during induction therapy. Safe administration of chemotherapy after CM-HUS recovery was challenging. By closely monitoring hemolytic and renal parameters during the 2-year treatment period, we observed four episodes of microangiopathic hemolytic anemia (MAHA) with hypocomplementemia and low haptoglobin but no renal dysfunction or thrombocytopenia. Here, we describe the MAHA and CM-HUS episodes in the hopes of elucidating the complex pathophysiology of disorders associated with CFH mutation.

Efficacy of cascade plasmapheresis in comparison with conventional therapeutic plasma exchange for relapsed atypical hemolytic uremic syndrome: A case report

Atypical hemolytic uremic syndrome (aHUS) is a rare and life-threatening disease that is associated with high mortality and morbidity. The incidence of aHUS is about 1 or 2 cases per 1,000,000 per year. Etiology can be either familial or sporadic. The pathogenesis of aHUS involves dysregulation of the alternative complement pathway, with predisposing mutations in complement genes. aHUS has a poor prognosis and a gradual or a relapsing (30%-86%) clinical course. The disease may present at any age but is mostly seen in children and young adults. Therapeutic plasma exchange (TPE) is one of the primary modalities of treatment in aHUS. This report presents the utilization of cascade plasmapheresis and its advantages over TPE in a patient with relapsed aHUS. There was a 73% decrement in antifactor H antibody levels following cascade plasmapheresis.

Systematic review of atypical hemolytic uremic syndrome biomarkers

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

A Guide for Adult Nephrologists and Hematologists to Managing Atypical Hemolytic Uremic Syndrome and C3 Glomerulopathy in Teens Transitioning to Young Adults

Atypical hemolytic uremic syndrome and C3 glomerulopathy/immune complex membranoproliferative glomerulonephritis are ultra-rare chronic, complement-mediated diseases with childhood manifestation in a majority of cases. Transition of clinical care of patients from pediatric to adult nephrologists-typically with controlled disease in native or transplant kidneys in case of atypical hemolytic uremic syndrome and often with chronic progressive disease despite treatment efforts in case of C3 glomerulopathy/immune complex membranoproliferative glomerulonephritis-identifies a challenging juncture in the journey of these patients. Raising awareness for the vulnerability of this patient cohort; providing education on disease pathophysiology and management including the use of new, high-precision complement antagonists; and establishing an ongoing dialog of patients, families, and all members of the health care team involved on either side of the age divide will be inevitable to ensure optimal patient outcomes and a safe transition of these patients to adulthood.

Eculizumab in low-middle income countries: how much does a life cost?

Atypical hemolytic uremic syndrome (aHUS) is an ultra-rare disease and eculizumab was approved as first line therapy in 2011 by the Food and Drug Administration. Access to eculizumab in low-middle income countries is challenging. We discuss access to eculizumab in Brazil that was made possible by judicialization or compassionate use. We showed a nationwide cohort of unplanned eculizumab interruptions resulted in higher rates of aHUS relapse. Similar to the French cohort, the use of eculizumab after transplantation showed superior graft survival compared to conventional treatment. We speculate a possible solution to the higher cost of eculizumab in which the government negotiates with the manufacturers. In this process, the government should compromise to ensure validated protocols of drug use, and the pharmaceutical companies, on the other hand, should reduce prices, especially in low-income countries. We also suggest a price adjustment based on gross domestic product.

A novel missense mutation in complement factor I predisposes patients to atypical hemolytic uremic syndrome: a case report

Background

Atypical hemolytic uremic syndrome, also called the nondiarrheal form of hemolytic uremic syndrome, is a rare disease characterized by the triad of thrombocytopenia, Coomb’s test-negative microangiopathic hemolytic anemia, and acute renal failure. Approximately 60% of cases of atypical hemolytic uremic syndrome are associated with deficiencies of the complement regulatory protein, including mutations in complement factor H, complement factor I, or the membrane co-factor protein.

Case presentation

We report the case of a 26-year-old Asian man who presented with pulmonary infection, elevated blood pressure, microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Renal biopsy revealed diffuse capillary fibrin deposition, endothelial swelling, and arteriole narrowing like “onion skinning” consistent with thrombotic microangiopathy. Bidirectional sequencing of CFH, CFHR5, CFHR1, CFI, DGKE, CFB, and MCP confirmed that the patient was heterozygous for a novel missense mutation, p.Cys67Phe, in CFI. This patient had rapid evolution to end-stage renal disease and needed renal replacement therapy. Plasma exchange seemed inefficacious in this patient.

Conclusions

This report confirms the importance of screening patients with atypical hemolytic uremic syndrome for mutations in genes involved in complement system to clarify the diagnosis and demonstrates the challenges in the management of these patients.

Thrombotic Microangiopathy Syndromes-Common Ground and Distinct Frontiers

Thrombotic microangiopathies (TMAs) have in common a terminal phenotype of microangiopathic hemolytic anemia with end-organ dysfunction. Thrombotic thrombocytopenic purpura results from von Willebrand factor multimerization, Shiga toxin-mediated hemolytic uremic syndrome causes toxin-induced endothelial dysfunction, while atypical hemolytic uremic syndrome results from complement system dysregulation. Drug-induced TMA, rheumatological disease-induced TMA, and renal-limited TMA exist in an intermediate space that represents secondary complement activation and may overlap with atypical hemolytic uremic syndrome clinically. The existence of TMA without microangiopathic hemolytic features, renal-limited TMA, represents an undiscovered syndrome that responds incompletely and inconsistently to complement blockade. Hematopoietic stem cell transplant-TMA represents another more resistant form of TMA with different therapeutic needs and clinical course. It has become apparent that TMA syndromes are an emerging field in nephrology, rheumatology, and hematology. Much work remains in genetics, molecular biology, and therapeutics to unravel the puzzle of the relationships and distinctions apparent between the different subclasses of TMA syndromes.

[A hemolytic episode following COVID-19 in a case with atypical hemolytic uremic syndrome]

Atypical hemolytic uremic syndrome (aHUS) is a lethal disease resulting in systemic thrombotic microangiopathies due to complement dysregulation. Immune activation by viral infections, such as SARS-CoV-2, may trigger hemolytic attack. A 38-year-old man, who had been previously diagnosed with aHUS due to complement component 3 mutation, was proven to be positive for SARS-CoV-2 without respiratory symptoms. No specific intervention was given to the patient, and he developed hematuria and oliguria three days after diagnosis. The patient was subsequently referred to our hospital and treated with eculizumab (900 mg). Afterward, the hemolytic symptoms improved rapidly. To the best of our knowledge, there have been reports of at least ten cases of hemolysis triggered by COVID-19 in patients with aHUS, and a potential clinical benefit of eculizumab for hemolytic attack, as well as for COVID-19, has been suggested. Here, we report the findings of a case, which indicate the efficacy of eculizumab introduction at an early stage.

Case series: coronavirus disease 2019 infection as a precipitant of atypical hemolytic uremic syndrome: two case reports

Background

Atypical hemolytic uremic syndrome is an exceedingly rare thrombotic microangiopathy caused by accelerated activation of the alternative complement pathway.

Case presentation

Here, we report two cases of patients presenting with suspected atypical hemolytic uremic syndrome precipitated by coronavirus disease 2019 infection. The first patient, a 25-year-old Hispanic male, had one prior episode of thrombotic microangiopathy presumed to be atypical hemolytic uremic syndrome precipitated by influenza A, and re-presented with thrombocytopenia, microangiopathic hemolytic anemia, nonoliguric renal failure, and normal ADAMTS13 activity, with confirmed coronavirus disease 2019 positivity. The second patient, a 31-year-old Caucasian female, had no personal history of thrombotic microangiopathy, though reported a family history of suspected atypical hemolytic uremic syndrome. She presented with similar laboratory derangements, oliguric renal failure requiring hemodialysis, and confirmed coronavirus disease 2019 positivity. Both patients were treated with eculizumab with complete resolution of their hematologic and renal complications.

Conclusion

To our knowledge, this represents the largest case series of atypical hemolytic uremic syndrome precipitated by coronavirus disease 2019 in adults.

Thrombotic Microangiopathy Triggered by COVID-19: Case Reports

SARS-CoV-2 causes thrombotic microangiopathy (TMA) through the activation of an alternative and lectin complement pathway. TMA is one of the main reasons for acute kidney injury development in patients with COVID-19. In this study, we present 3 TMA cases with severe kidney injury triggered by SARS-CoV-2. In the absence of other TMA causes, we diagnosed the atypical hemolytic uremic syndrome, triggered by SARS-CoV-2 due to abnormal complement activation. Because of both coagulation factors activation, and the high level of D-dimer in patients with COVID-19, it is crucial to differentiate disseminated intravascular coagulation from TMA. The use of anticomplement therapies such as eculizumab should be considered in refractory cases of progressive COVID-19. Controlled clinical trials are required before a definitive statement can be made.

Atypical Hemolytic Uremic Syndrome after ChAdOx1 nCoV-19 Vaccination in a Patient with Homozygous CFHR3/CFHR1 Gene Deletion

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy (TMA) affecting the kidneys. Compared with typical HUS due to an infection from shiga toxin-producing Escherichia coli, atypical HUS involves a genetic or acquired dysregulation of the complement alternative pathway. In the presence of a mutation in a complement gene, a second trigger is often necessary for the development of the disease. We report a case of a 54-year-old female, with a past medical history of pulmonary tuberculosis, who was admitted to the emergency service with general malaise and reduction in urine output, 5 days after vaccination with ChAdOx1 nCoV-19. Laboratory results revealed microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Given the clinical picture of TMA, plasma exchange (PEX) was immediately started, along with hemodialysis. Complementary laboratory workup for TMA excluded thrombotic thrombocytopenic purpura and secondary causes. Complement study revealed normal levels of factors H, B, and I, normal activity of the alternate pathway, and absence of anti-factor H antibodies. Genetic study of complement did not show pathogenic variants in the 12 genes analyzed, but revealed a deletion in gene CFHR3/CFHR1 in homozygosity. Our patient completed 10 sessions of PEX, followed by eculizumab, with both clinical and laboratorial improvement. Actually, given the short time lapse between vaccination with ChAdOx1 nCoV-19 and the clinical manifestations, we believe that vaccine was the trigger for the presentation of aHUS in this particular case.

Atypical hemolytic uremic syndrome in the Colombian Caribbean: its particular characteristics

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare and genetically mediated systemic disease most often caused by uncontrolled and chronic complement activation that leads to systemic thrombotic microangiopathy, renal and extra-renal damage.

Materials and methods

This is descriptive, retrospective and multicenter study, which reports demographic, clinical, laboratory, and genetic characteristics, as well as their treatment response and outcome of 20 aHUS patients diagnosed between 2014 and 2018.

Results

Most patients were female adults (75%) and 30% were associated to pregnancy/postpartum, 15% to autoimmune disease, and 65% to infections. Gastrointestinal involvement (75%) was the most frequent extra-renal organ damage. Antenatal mortality and mortality rate were 5% and 10%, respectively. 25% of the patients progressed to end-stage renal disease. In 4/8 of patients treated within 1 week of presentation, eculizumab treatment restored multi-organ function after 4 weeks of treatment. CFH (37%) and CFI (25%) mutations were the most frequent.

Conclusion

This is the first series of aHUS cases of Colombian Caribbean region which reports the clinical and epidemiological characteristics of this condition in this region.

Pregnancy in Women with Atypical Hemolytic Uremic Syndrome

BACKGROUND

Pregnancy outcomes in patients with atypical hemolytic uremic syndrome (aHUS) are not well-documented. Here, we present characteristics of and outcomes for patients with aHUS who became pregnant while enrolled in the Global aHUS Registry.

METHODS

The observational Global aHUS Registry (NCT01522183), initiated in April 2012, collects demographics, disease history, treatment, and outcomes data for patients with aHUS, regardless of treatment approach. This descriptive analysis includes patients from the Registry with evaluable pregnancy data supplemented with pharmacovigilance information; the number of pregnancies, outcomes, and exposure to eculizumab were evaluated.

RESULTS

As of April 1, 2019, 44 pregnancies were recorded in 41 patients, with 24 pregnancies exposed to eculizumab. Pathogenic variants were identified in 48.8% of patients. Three patients were on dialysis and 6 patients had a kidney graft at the time of pregnancy. Excluding elective terminations, 85.3% of pregnancies resulted in live births. Elective terminations were recorded in 22.7% of pregnancies, miscarriages occurred in 9.1% of pregnancies, and late fetal death in 2.3% of pregnancies. No malformations or anomalies were reported.

CONCLUSIONS

Our results show that in women with aHUS, even on dialysis or with a kidney graft, pregnancy is possible with careful monitoring for aHUS flares and prematurity. Prophylactic or therapeutic eculizumab offers disease control with low-risk of fetal abnormalities.

Eculizumab exposure in children and young adults: indications, practice patterns, and outcomes-a Pediatric Nephrology Research Consortium study

BACKGROUND

Eculizumab is approved for the treatment of atypical hemolytic uremic syndrome (aHUS). Its use off-label is frequently reported. The aim of this study was to describe the broader use and outcomes of a cohort of pediatric patients exposed to eculizumab.

METHODS

A retrospective, cohort analysis was performed on the clinical and biomarker characteristics of eculizumab-exposed patients < 25 years of age seen across 21 centers of the Pediatric Nephrology Research Consortium. Patients were included if they received at least one dose of eculizumab between 2008 and 2015. Traditional summary statistics were applied to demographic and clinical data.

RESULTS

A total of 152 patients were identified, mean age 9.1 (+/-6.8) years. Eculizumab was used "off-label" in 44% of cases. The most common diagnoses were aHUS (47.4%), Shiga toxin-producing Escherichia coli HUS (12%), unspecified thrombotic microangiopathies (9%), and glomerulonephritis (9%). Genetic testing was available for 60% of patients; 20% had gene variants. Dosing regimens were variable. Kidney outcomes tended to vary according to diagnosis. Infectious adverse events were the most common adverse event (33.5%). No cases of meningitis were reported. Nine patients died of noninfectious causes while on therapy.

CONCLUSIONS

This multi-center retrospective cohort analysis indicates that a significant number of children and young adults are being exposed to C5 blockade for off-label indications. Dosing schedules were highly variable, limiting outcome conclusions. Attributable adverse events appeared to be low. Cohort mortality (6.6%) was not insignificant. Prospective studies in homogenous disease cohorts are needed to support the role of C5 blockade in kidney outcomes.

Thrombotic microangiopathy during pregnancy

Pregnancy is a high-risk time for the development of different kinds of thrombotic microangiopathy (TMA). Three major syndromes including TTP (thrombotic thrombocytopenic purpura), PE/HELLP (preeclampsia/hemolysis, elevated liver function tests, low platelets), and aHUS (atypical hemolytic- uremic syndrome) should be sought in pregnancy-TMA. These severe disorders share multiple clinical features and overlaps and even the coexistence of more than one pathologic mechanism. Each of these disorders finally ends in endothelial damage and fibrin thrombi formation within the microcirculation that fragments RBCs (schystocytes), aggregates platelets, and creates ischemic injury in the targeted organs i.e.; kidney and brain. Although the mechanisms of these severe disorders have been revealed, pregnancy-related TMA still interfaces with diagnostic and therapeutic challenges. Here, we highlight the current knowledge of diagnosis and management of these complications during pregnancy.

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

INTRODUCTION

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Atypical Evolution of Secondary Hemolytic Uremic Syndrome Defined as Paraneoplastic Syndrome under Eculizumab and Palbociclib Therapies

Thrombotic microangiopathy (TMA) is most of the time caused by thrombotic thrombocytopenic purpura or hemolytic uremic syndrome. A 60-year-old female was diagnosed in 2014 with mammary breast adenocarcinoma treated by several-line therapy: mastectomy, docetaxel, cyclophosphamide, radiotherapy, doxorubicine, and capecitabine. By mid-November, the patient was admitted to the hospital with regenerative, mechanical, and hemolytic anemia, schistocytes at 3%, and thrombopenia (99 G/L), associated with high blood transfusion requirement. After 9 sessions of plasmapheresis, there was no significant improvement in the biological parameters, nor after 2 cycles of paclitaxel. The patient was then treated with eculizumab during 4 weeks, with a slight reduction in blood requirement, and simultaneously with palbociclib. Since being treated with palpociclib, she had a great reduction in blood requirement and a good clinical condition. To conclude, we reported an initial moderate improvement of paraneoplasm-related TMA syndrome under eculizumab therapy with a slight reduction in red blood cell requirement; however, palbociclib therapy achieved a very good response with a dramatic reduction in red blood cell requirement.

The long-acting C5 inhibitor, ravulizumab, is efficacious and safe in pediatric patients with atypical hemolytic uremic syndrome previously treated with eculizumab

BACKGROUND

Atypical hemolytic uremic syndrome (aHUS) is a rare, complement-mediated disease associated with poor outcomes if untreated. Ravulizumab, a long-acting C5 inhibitor developed through minimal, targeted modifications to eculizumab was recently approved for the treatment of aHUS. Here, we report outcomes from a pediatric patient cohort from the ravulizumab clinical trial (NCT03131219) who were switched from chronic eculizumab to ravulizumab treatment.

METHODS

Ten patients received a loading dose of ravulizumab on Day 1, followed by maintenance doses administered initially on Day 15, and then, every 4-8 weeks thereafter, depending on body weight. All patients completed the initial evaluation period of 26 weeks and entered the extension period.

RESULTS

No patients required dialysis at any point throughout the study. The median estimated glomerular filtration rate values remained stable during the trial: 99.8 mL/min/1.73m2 at baseline, 93.5 mL/min/1.73m2 at 26 weeks, and 104 mL/min/1.73m2 at 52 weeks. At last available follow-up, all patients were in the same chronic kidney disease stage as recorded at baseline. Hematologic variables (platelets, lactate dehydrogenase, and hemoglobin) also remained stable throughout the initial evaluation period and up to the last available follow-up. All patients experienced adverse events; the most common were upper respiratory tract infection (40%) and oropharyngeal pain (30%). There were no meningococcal infections reported, no deaths occurred, and no patients discontinued during the study.

CONCLUSIONS

Overall, treatment with ravulizumab in pediatric patients with aHUS who were previously treated with eculizumab resulted in stable kidney and hematologic parameters, with no unexpected safety concerns when administered every 4-8 weeks.

TRIAL REGISTRATION

Trial identifiers: Trial ID: ALXN1210-aHUS-312 Clinical trials.gov : NCT03131219 EudraCT number: 2016-002499-29 Graphical abstract.

Complement-Mediated Thrombotic Microangiopathy Associated with Lupus Nephritis Treated with Eculizumab: A Case Report

Thrombotic microangiopathies (TMAs) involve multiple organ systems due to the presence of microangiopathic hemolysis. One such condition, atypical hemolytic uremic syndrome (aHUS), is a complement-mediated process that is part of a spectrum of disorders that have underlying complement dysfunction of the alternative pathway due to overactivity or decreased self-nonself discrimination by innate immunity. Complement-amplifying conditions such as pregnancy may unmask a diagnosis of aHUS. We present an important case of a pregnant 23-year-old Hispanic female who presented in mid-gestation (21 weeks) with an initial diagnosis of systemic lupus erythematosus (SLE) complicated by aHUS. She met clinical criteria for aHUS on presentation and was found to have a pathogenic CFHR1–3 homozygous deletion. She has been treated with intravenous and oral steroids, cyclophosphamide, subsequently also with plasma exchange, and finally with eculizumab with partial improvement in renal function. This case adds to the emerging literature showing that SLE and aHUS (or complement-mediated TMA) can be successfully treated with C5 blockade.

Anti-complement factor H (CFH) antibodies and a novel CFH gene mutation in an atypical hemolytic uremic syndrome patient with complement activation of the classical pathway

Atypical hemolytic uremic syndrome (aHUS) is a rare disease caused by overactivation of the complement alternative pathway. aHUS involves the presence of antibodies against complement factor H and its mutations in the complement genes. A 2-month-old boy presented with discoid rash, hemolytic anemia, thrombocytopenia, multiple antibodies, and hypocomplementemia with a very low level of C4 (< 3 mg/dL), indicating activation of the complement pathway, together fulfilling the systemic lupus erythematosus (SLE) criteria of the American College of Rheumatology at 5 months of age. However, most of these findings normalized spontaneously without any intervention. Further investigations revealed a high level of anti-complement factor H antibodies and a novel heterozygous missense mutation (p.Glu1172Ala, located in exon 22) in a complement gene, CFH. At 2 years of age, his SLE-like symptoms have not recurred, but hematuria and schistocytes were persistent. Eventually, aHUS was diagnosed rather than SLE. Our findings suggest that multiple antibody complex, including anti-complement factor H antibody, may temporarily activate the classical pathway, resulting in SLE-like findings.