Eculizumab in the treatment of atypical hemolytic uremic syndrome in an infant leads to cessation of peritoneal dialysis and improvement of severe hypertension

Protein-losing enteropathy as a new phenotype in atypical hemolytic uremic syndrome caused by CD46 gene mutation

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 m2. 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.

Prophylactic amoxicillin for the prevention of meningococcal infection in infants with atypical hemolytic uremic syndrome under treatment with eculizumab: a report of two cases

Eculizumab, a humanized monoclonal antibody to complement C5, is a therapeutic drug for atypical hemolytic-uremic syndrome (aHUS) that inhibits the terminal pathway of complement. Patients on eculizumab therapy may become more susceptible to infection with capsule-forming bacteria, including meningococci. Therefore, meningococcal vaccination is required for patients who are on eculizumab therapy. However, the means to prevent meningococcal infection in infants who cannot be vaccinated with the available meningococcal vaccine have not yet been established internationally. In two infants with aHUS at 4-5 months after birth, prophylactic oral amoxicillin was administered, and meningococcal infection was not detected during the period between the initiation of eculizumab therapy and the administration of meningococcal vaccine. Neither adverse events related to amoxicillin nor thrombotic microangiopathy occurred during the treatment. Thus, oral administration of amoxicillin may be effective for preventing meningococcal infection under treatment with eculizumab in infants who have not received meningococcal vaccination.

Is eculizumab indicated in patients with atypical hemolytic uremic syndrome already on prolonged dialysis? A case report and review of the literature

BACKGROUND

Eculizumab has caused a revolution in the treatment and prognosis of atypical hemolytic uremic syndrome. Early initiation of treatment is recommended to increase chances of renal recovery.

CASE-DIAGNOSIS/TREATMENT

We describe a boy with atypical hemolytic uremic syndrome who started eculizumab therapy after being on dialysis for 4.5 months, with complete anuria. With treatment, he was weaned off dialysis.

CONCLUSION

We review the evidence in the literature and discuss the possible mechanism by which eculizumab induces renal recovery even in patients already on prolonged dialysis. This case report highlights the importance of a treatment trial with eculizumab, even in patients already on prolonged dialysis.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Hypertension: a new treatment for an old disease? Targeting the immune system

Arterial hypertension represents a serious public health problem, being a major cause of morbidity and mortality worldwide. The availability of many antihypertensive therapeutic strategies still fails to adequately treat around 20% of hypertensive patients, who are considered resistant to conventional treatment. In the pathogenesis of hypertension, immune system mechanisms are activated and both the innate and adaptive immune responses play a crucial role. However, what, when and how the immune system is triggered during hypertension development is still largely undefined. In this context, this review highlights scientific advances in the manipulation of the immune system in order to attenuate hypertension and end-organ damage. Here, we discuss the potential use of immunosuppressants and immunomodulators as pharmacological tools to control the activation of the immune system, by non-specific and specific mechanisms, to treat hypertension and improve end-organ damage. Nevertheless, more clinical trials should be performed with these drugs to establish their therapeutic efficacy, safety and risk-benefit ratio in hypertensive conditions. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Pathogenesis of Atypical Hemolytic Uremic Syndrome

Atypical hemolytic uremic syndrome (aHUS) is a type of thrombotic microangiopathy (TMA) defined by thrombocytopenia, microangiopathic hemolytic anemia, and renal failure. aHUS is caused by uncontrolled complement activation in the alternative pathway (AP). A variety of genetic defects in complement-related factors or acquired autoantibodies to the complement regulators have been found in 50 to 60% of all cases. Recently, however, the classification and diagnosis of aHUS are becoming more complicated. One reason for this is that some factors, which have not been regarded as complement-related factors, have been reported as predisposing factors for phenotypic aHUS. Given that genotype is highly correlated with the phenotype of aHUS, careful analysis of underlying genetic abnormalities or acquired factors is needed to predict the prognosis or to decide an optimal treatment for the disease. Another reason is that complement dysregulation in the AP have also been found in a part of other types of TMA such as transplantation-related TMA and pregnancy-related complication. Based on these findings, it is now time to redefine aHUS according to the genetic or acquired background of abnormalities.Here, we review the pathogeneses and the corresponding phenotypes of aHUS and complement-related TMAs.

Clinical characteristics and genetic backgrounds of Japanese patients with atypical hemolytic uremic syndrome

Background

Atypical hemolytic uremic syndrome (aHUS) is caused by complement overactivation, and its presentation and prognosis differ according to the underlying molecular defects. The aim of this study was to characterize the genetic backgrounds of aHUS patients in Japan and to elucidate the associations between their genetic backgrounds, clinical findings, and outcomes.

Methods

We conducted a nationwide epidemiological survey of clinically diagnosed aHUS patients and examined 118 patients enrolled from 1998 to 2016 in Japan. We screened variants of seven genes related to complement and coagulation, as well as positivity for anti-CFH antibodies, and assessed clinical manifestations, laboratory findings, and clinical course.

Results

The most frequent genetic abnormalities were in C3 (31%) and the frequency of CFH variants was relatively low (10%) compared to Western countries. The predominant variant in this cohort was C3 p.I1157T (23%), which was related to favorable outcomes despite frequent relapses. A total of 72% of patients received plasma therapy, while 42% were treated with eculizumab. The prognosis of Japanese aHUS patients was relatively favorable, with a total mortality rate of 5.4% and a renal mortality rate of 15%.

Conclusions

The common occurrence of genotype C3, especially the p.I1157T variant was the characteristic of the genetic backgrounds of Japanese aHUS patients that differed from those of Caucasian patients. In addition, the favorable prognosis of patients with the unique C3 p.I1157T variant indicates that understanding the clinical characteristics of individual gene alterations is important for predicting prognosis and determining therapeutic strategies in aHUS.

Electronic supplementary material

The online version of this article (10.1007/s10157-018-1549-3) contains supplementary material, which is available to authorized users.

Atypical hemolytic uremic syndrome in the setting of complement-amplifying conditions: case reports and a review of the evidence for treatment with eculizumab

Atypical hemolytic uremic syndrome (aHUS) is a rare, genetic, progressive, life-threatening form of thrombotic microangiopathy (TMA) predominantly caused by dysregulation of the alternative pathway of the complement system. Complement-amplifying conditions (CACs), including pregnancy complications [preeclampsia, HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome], malignant hypertension, autoimmune diseases, transplantation, and others, are associated with the onset of TMA in up to 69 % of cases of aHUS. CACs activate the alternative pathway of complement and may be comorbid with aHUS or may unmask a previously undiagnosed case. In this review, three case reports are presented illustrating the onset and diagnosis of aHUS in the setting of different CACs (pregnancy complications, malignant hypertension, renal transplantation). The report also reviews the evidence for a variety of CACs, including those mentioned above as well as infections and drug-induced TMA, and the overlap with aHUS. Finally, we introduce an algorithm for diagnosis and treatment of aHUS in the setting of CACs. If TMA persists despite initial management for the specific CAC, aHUS should be considered. The terminal complement inhibitor eculizumab should be initiated for all patients with confirmed diagnosis of aHUS, with or without a comorbid CAC.

Neonatal atypical hemolytic uremic syndrome from a factor H mutation treated with eculizumab

Background: Atypical hemolytic uremic syndrome (aHUS) results from an inherited dysregulation of the alternative complement pathway leading to thrombotic microangiopathy consisting of hemolytic anemia, thrombocytopenia, and renal injury. The complement inhibitor eculizumab is an approved treatment, but its reported use in neonates – who have an inherently high risk of infection – is limited. Case diagnosis/treatment: A 28-day-old female presented with gross hematuria and hypertension. aHUS was suspected based on anemia with schistocytes, thrombocytopenia, low C3, and acute kidney injury requiring peritoneal dialysis. A septic work-up initiated on day 2 for hypothermia and respiratory failure was negative. There was no improvement after 6 days of plasma therapy. Despite being < 6 weeks old she was vaccinated with pneumococcal-13 conjugate, meningococcal (groups C and Y) polysaccharide, and Haemophilus b tetanus toxoid conjugate vaccines and started on penicillin prophylaxis. After 1 dose of eculizumab 300 mg, dialysis was discontinued and her hematological parameters improved. Genetic testing revealed a complement factor H mutation. After 11 months of follow-up, she remains on eculizumab and penicillin without recurrence of aHUS or any infectious complications. Conclusions: Eculizumab is a safe and effective treatment option for aHUS even in neonates at high risk for infection.

Critical appraisal of eculizumab for atypical hemolytic uremic syndrome

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

Timing of eculizumab therapy for C3 glomerulonephritis

Eculizumab is an anti-C5 antibody that inhibits C5 cleavage and prevents the generation of the terminal complement complex C5b-9. Eculizumab is licensed to treat paroxysmal nocturnal haemoglobinuria or atypical haemolytic uraemic syndrome (aHUS). Clinical trials are ongoing for C3 glomerulopathy. Given the unfamiliarity of physicians with these rare diseases and the variability of clinical presentation, a delayed initiation of eculizumab therapy is common. Thus, the question arises as to what extent improvement of kidney function may be expected when patients have been dialysis dependent for weeks or months already when eculizumab is initiated. Furthermore, given the high cost and potential adverse effects of eculizumab, the question arises of when to stop therapy because of futility when patients with kidney-only manifestations remain dialysis dependent. In literature reports, eculizumab was stopped as early as after 3 weeks because the patient remained dialysis dependent. In this issue of CKJ, Inman et al. report on eculizumab-induced reversal of dialysis-dependent kidney failure from C3 glomerulonephritis, illustrating both the potential benefit of eculizumab for this complement-mediated disease and the need for lengthy therapy—dialysis independency was reached after 5 months of eculizumab. Indeed, there are reports of renal function recovery when eculizumab was initiated after 4 months on dialysis and of recovery of renal function 2.0–3.5 months after initiation of eculizumab in dialysis-dependent patients with C3 glomerulopathy or aHUS.