Efficacy and Safety of Eculizumab in Pediatric Patients Affected by Shiga Toxin-Related Hemolytic and Uremic Syndrome: A Randomized, Placebo-Controlled Trial

Eculizumab for management of hyperhemolysis syndrome in pediatric patients with sickle cell disease: A single-center case series

Chronic hemolytic anemia and vascular occlusion are hallmarks of sickle cell disease (SCD). Blood transfusions are critical for supportive and preventive management of SCD complications. Patients with SCD are at risk for hyperhemolysis syndrome (HHS), a subtype of delayed hemolytic transfusion reactions. HHS management includes intravenous immunoglobulin, corticosteroids, and avoidance of further transfusions. Not all patients respond to first-line agents. Eculizumab, which blocks terminal complement activation, has been proposed as second-line management of HHS. We describe two patients who received eculizumab for refractory HHS. In our experience, eculizumab is a safe and effective option for refractory pediatric HHS.

Eculizumab in Shiga toxin-producing Escherichia coli hemolytic uremic syndrome: a systematic review

BACKGROUND

Infection-associated hemolytic uremic syndrome (IA-HUS), most often due to infection with Shiga toxin-producing bacteria, mainly affects young children. It can be acutely life-threatening, as well as cause long-term kidney and neurological morbidity. Specific treatment with proven efficacy is lacking. Since activation of the alternative complement pathway occurs in HUS, the monoclonal C5 antibody eculizumab is often used off-label once complications, e.g., seizures, occur. Eculizumab is prohibitively expensive and carries risk of infection. Its utility in IA-HUS has not been systematically studied. This systematic review aims to present, summarize, and evaluate all currently available data regarding the effect of eculizumab administration on medium- to long-term outcomes (i.e., outcomes after the acute phase, with a permanent character) in IA-HUS.

METHODS

PubMed, Embase, and Web of Science were systematically searched for studies reporting the impact of eculizumab on medium- to long-term outcomes in IA-HUS. The final search occurred on March 2, 2022. Studies providing original data regarding medium- to long-term outcomes in at least 5 patients with IA-HUS, treated with at least one dose of eculizumab during the acute illness, were included. No other restrictions were imposed regarding patient population. Studies were excluded if data overlapped substantially with other studies, or if outcomes of IA-HUS patients were not reported separately. Study quality was assessed using the ROBINS-I tool for risk of bias in non-randomized studies of interventions. Data were analyzed descriptively.

RESULTS

A total of 2944 studies were identified. Of these, 14 studies including 386 eculizumab-treated patients met inclusion criteria. All studies were observational. Shiga toxin-producing E. coli (STEC) was identified as the infectious agent in 381 of 386 patients (98.7%), effectively limiting the interpretation of the data to STEC-HUS patients. Pooling of data across studies was not possible. No study reported a statistically significant positive effect of eculizumab on any medium- to long-term outcome. Most studies were, however, subject to critical risk of bias due to confounding, as more severely ill patients received eculizumab. Three studies attempted to control for confounding through patient matching, although residual bias persisted due to matching limitations.

DISCUSSION

Current observational evidence does not permit any conclusion regarding the impact of eculizumab in IA-HUS given critical risk of bias. Results of randomized clinical trials are eagerly awaited, as new therapeutic strategies are urgently needed to prevent long-term morbidity in these severely ill patients.

SYSTEMATIC REVIEW REGISTRATION NUMBER

OSF Registries, MSZY4, Registration DOI https://doi.org/10.17605/OSF.IO/MSZY4 .

Outcome 10 years after Shiga toxin-producing E. coli (STEC)-associated hemolytic uremic syndrome: importance of long-term follow-up

BACKGROUND

Hemolytic uremic syndrome (HUS) is an important cause of acute kidney injury in children. HUS is known as an acute disease followed by complete recovery, but patients may present with kidney abnormalities after long periods of time. This study evaluates the long-term outcome of Shiga toxin-producing Escherichia coli-associated HUS (STEC-HUS) in pediatric patients, 10 years after the acute phase of disease to identify risk factors for long-term sequelae.

METHODS

Over a 6-year period, 619 patients under 18 years of age with HUS (490 STEC-positive, 79%) were registered in Austria and Germany. Long-term follow-up data of 138 STEC-HUS-patients were available after 10 years for analysis.

RESULTS

A total of 66% (n = 91, 95% CI 0.57-0.73) of patients fully recovered showing no sequelae after 10 years. An additional 34% (n = 47, 95% CI 0.27-0.43) presented either with decreased glomerular filtration rate (24%), proteinuria (23%), hypertension (17%), or neurological symptoms (3%). Thirty had sequelae 1 year after STEC-HUS, and the rest presented abnormalities unprecedented at the 2-year (n = 2), 3-year (n = 3), 5-year (n = 3), or 10-year (n = 9) follow-up. A total of 17 patients (36.2%) without kidney abnormalities at the 1-year follow-up presented with either proteinuria, hypertension, or decreased eGFR in subsequent follow-up visits. Patients needing extracorporeal treatments during the acute phase were at higher risk of presenting symptoms after 10 years (p < 0.05).

CONCLUSIONS

Patients with STEC-HUS should undergo regular follow-up, for a minimum of 10 years following their index presentation, due to the risk of long-term sequelae of their disease. An initial critical illness, marked by need of kidney replacement therapy or plasma treatment may help predict poor long-term outcome.

Constipation and hemolytic uremic syndrome

BACKGROUND

Shiga toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) classically presents with diarrhea. Absence of diarrheal prodrome increases suspicion for atypical HUS (aHUS). Inability to obtain a fecal specimen for culture or culture-independent testing limits the ability to differentiate STEC-HUS and aHUS.

CASE-DIAGNOSIS/TREATMENT

Our patient presented with abdominal pain and constipation, and evaluation of pallor led to a diagnosis of HUS. There was a complete absence of diarrhea during the disease course. Lack of fecal specimen for several days delayed testing for STEC. Treatment for atypical HUS was initiated with complement-blockade therapy. PCR-testing for Shiga toxin from fecal specimen later returned positive. Alternative complement-pathway testing did not identify a causative genetic variant or anti-Factor H antibody. A diagnosis of STEC-HUS was assigned, and complement-blockade therapy was stopped.

CONCLUSION

Diagnosis of aHUS remains a diagnosis of exclusion, whereby other causes of HUS are eliminated with reasonable certainty. Exclusion of STEC is necessary and relies on testing availability and recognition of testing limitations. Diarrhea-negative STEC-HUS remains a minority of cases, and future research is needed to explore the clinical characteristics of these patients.

Eculizumab in STEC-HUS: a paradigm shift in the management of pediatric patients with neurological involvement

BACKGROUND

Eculizumab for the treatment of atypical hemolytic uremic syndrome (HUS) is a standard of care. Central nervous system (CNS) involvement in Shiga toxin-producing Escherichia coli (STEC)-HUS is associated with increased morbidity and mortality. There is no consensus on the use of plasma exchange and/or eculizumab. We report a series (n = 4) of children with CNS involvement in STEC-HUS with excellent outcomes after treatment with eculizumab only and supportive therapies.

METHODS

A retrospective chart review of patients with CNS involvement in STEC-HUS is managed with supportive therapies and eculizumab only.

RESULTS

Four patients (75% female) with a median age of 5 years and 11 months (IQR: 23.5-105.5 months) were admitted to a tertiary pediatric nephrology center with CNS involvement in STEC-HUS. Neurological symptoms presented between days 2 and 7 of illness and included ataxia, altered mental status, visual symptoms, and seizures. All had an abnormal MRI brain. All received two doses of eculizumab, 1 week apart (dosing according to weight). Resolution of neurological symptoms was evident at a mean of 60 h post-administration (range: 24-72 h). All patients have complete kidney and neurological recovery at 12-month follow-up.

CONCLUSION

We present a case series of four children with STEC-HUS and CNS involvement, managed with eculizumab only, in lieu of plasma exchange (as per our previous policy). The marked improvement in symptoms in our cohort supports the use of eculizumab, rather than plasma exchange in the CNS involvement of STEC-HUS.

Ex Vivo Test of Complement Dysregulation in Atypical Hemolytic Uremic Syndrome Kidney Transplant patients: A Pilot Study

Introduction

In 2014, a complement assay, which evaluates C5b-9 deposition on endothelial cells, was proposed as a biomarker for atypical hemolytic uremic syndrome (aHUS). Early diagnosis and/or prediction of aHUS (relapse) is pivotal in aHUS kidney transplant recipients who do not receive eculizumab prophylaxis.

Methods

In this pilot study, serum samples of transplanted patients with aHUS in remission without eculizumab and patients with other primary kidney diseases (controls) were blinded and evaluated in the complement assay.

Results

We included 13 patients with aHUS (4 males, 9 females) of median age of 54 years (range: 35-69) and median of 5.9 years (range: 0.25-14.1) after transplantation; and 13 controls (7 males, 6 females) of median age of 42 years (range: 27-60) and median of 5.8 years (range: 1.6-11.7) after transplantation. There were no significant differences in C5b-9 deposits between patients with aHUS and controls on resting cells (median of 136% [range: 93%-382%] and 121% [range: 75%-200%], respectively) and activated cells (median of 196% [range: 99%-388%] and 170% [range: 113%-260%], respectively). Three patients with aHUS and 4 controls showed elevated C5b-9 deposits on resting cells, which should correspond to active aHUS. None of these patients had laboratory signs of thrombotic microangiopathy (TMA). During follow-up (15.8 months, range: 6-21), estimated glomerular filtration rate remained stable in all. In 5 patients with aHUS with a genetic variant, no increase in C5b-9 deposits was found on activated endothelial cells, which contrasts with the literature suggesting that the test should identify carriers of a genetic variant.

Conclusion

Our data question the routine use of the ex vivo complement assay in kidney transplant patients. Future studies should evaluate the test characteristics of assay in kidney transplant patients.

Shiga toxin targets the podocyte causing hemolytic uremic syndrome through endothelial complement activation

BACKGROUND

Shiga toxin (Stx)-producing Escherichia coli hemolytic uremic syndrome (STEC-HUS) is the leading cause of acute kidney injury in children, with an associated mortality of up to 5%. The mechanisms underlying STEC-HUS and why the glomerular microvasculature is so susceptible to injury following systemic Stx infection are unclear.

METHODS

Transgenic mice were engineered to express the Stx receptor (Gb3) exclusively in their kidney podocytes (Pod-Gb3) and challenged with systemic Stx. Human glomerular cell models and kidney biopsies from patients with STEC-HUS were also studied.

FINDINGS

Stx-challenged Pod-Gb3 mice developed STEC-HUS. This was mediated by a reduction in podocyte vascular endothelial growth factor A (VEGF-A), which led to loss of glomerular endothelial cell (GEnC) glycocalyx, a reduction in GEnC inhibitory complement factor H binding, and local activation of the complement pathway. Early therapeutic inhibition of the terminal complement pathway with a C5 inhibitor rescued this podocyte-driven, Stx-induced HUS phenotype.

CONCLUSIONS

This study potentially explains why systemic Stx exposure targets the glomerulus and supports the early use of terminal complement pathway inhibition in this devastating disease.

FUNDING

This work was supported by the UK Medical Research Council (MRC) (grant nos. G0901987 and MR/K010492/1) and Kidney Research UK (grant nos. TF_007_20151127, RP42/2012, and SP/FSGS1/2013). The Mary Lyon Center is part of the MRC Harwell Institute and is funded by the MRC (A410).