Outcome of atypical haemolytic uraemic syndrome relapse after eculizumab withdrawal

Recurrent complement-mediated Hemolytic uremic syndrome after kidney transplantation

Hereditary forms of hemolytic uremic syndrome (HUS), formerly known as atypical HUS, typically involve mutations in genes encoding for components of the alternative pathway of complement, therefore they are often referred to as complement-mediated HUS (cHUS). This condition has a high risk of recurrence in the transplanted kidney, leading to accelerated graft loss. The availability of anti-complement component C5 antibody eculizumab has enabled successful transplantation with a notably reduced recurrence rate and improved prognosis. Open questions are related to the potential for complement inhibitor discontinuation, ideal timing of treatment withdrawal, and patient selection based on genetic abnormalities. Our review delves into the pathophysiology, classification, genetic predispositions, and management strategies for cHUS in the native and transplant kidneys.

Clinical presentation and management of atypical hemolytic uremic syndrome in Latin America: a narrative review of the literature

INTRODUCTION

Comprehensive information about atypical hemolytic uremic syndrome (aHUS) is relatively scarce outside of Europe and North America. This narrative review assembles available published data about the clinical presentation and management of aHUS in Latin America.

AREAS COVERED

A search conducted in February 2023 of the MEDLINE (from inception), Embase (from inception), and LILACS/IBECS (1950 to 2023) databases using search terms 'atypical hemolytic uremic syndrome' and 'Latin America' and their variations retrieved 51 records (full papers and conference abstracts) published in English, Spanish, or Portuguese. After de-duplication, manual screening of titles/abstracts and addition of author-known articles, 25 articles were included of which 17 (68%) are full papers. All articles were published during the years 2013-2022. Articles include cohort studies, a registry analysis, and case reports from Argentina, Brazil, Chile and Columbia. Overall, Latin American patients with aHUS present the classic epidemiological, clinical, and genetic characteristics associated with this condition as described in other world regions. Depending on the country and time of reporting, aHUS in Latin America was treated mainly with plasma therapy and/or eculizumab. Where reported, eculizumab substantially improved aHUS-related outcomes in almost all adult and pediatric patients.

EXPERT OPINION

Eculizumab has dramatically altered the natural course of aHUS, improving prognosis and patient outcomes. Addressing economic challenges and investing in healthcare infrastructure will be essential to implement strategies for timely detection and early treatment of aHUS in Latin America.

New findings in preventing recurrence and improving renal function in AHUS patients after renal transplantation treated with eculizumab: a systemic review and meta-analyses

BACKGROUND

The long-term mortality of kidney transplantation patients with atypical hemolytic uremic syndrome remains high, and the efficacy of the main treatment eculizumab is still controversial.

OBJECTIVE

A comprehensive systematic review and meta-analysis of clinical trials using eculizumab in renal transplant patients with atypical hemolytic uremic syndrome was conducted to evaluate the efficacy of this therapy and its impact on renal function.

METHODS

A comprehensive systematic search was conducted across multiple reputable databases, including Ovid (MEDLINE, EMBASE), PubMed, and the Cochrane Library (since database inception), to identify relevant studies exploring the use of eculizumab in patients with atypical hemolytic uremic kidney transplantation. Various renal function parameters, such as dialysis, rejection, glomerular filtration rate, serum creatinine, lactate dehydrogenase, and platelet count, along with patient relapse rates, were extracted and summarized using a combination of robust statistical methods, including fixed effects, random effects, and general inverse variance methods.

RESULT

Eighteen trials with 618 subjects were analyzed. Our analysis suggests that the use of eculizumab is associated with a reduced likelihood of AHUS recurrence (odds ratio (OR) = 0.05, 95% CI: 0.00-0.13), as well as a significant reduction in the need for dialysis (odds ratio (OR) = 0.13, 95% CI: 0.01-0.32). Additionally, eculizumab treatment led to lower serum creatinine levels (mean differences (MD) = 126.931μmoI/L, 95% CI: 115.572μmoI/L-138.290μmoI/L) and an improved glomerular filtration rate (mean differences (MD) = 59.571 ml/min, 95% CI: 57.876 ml/min-61.266 mL/min). Our results also indicate that the use of eculizumab reduces the likelihood of rejection (odds ratio (OR) = 0.09, 95% CI: 0.01-0.22). Furthermore, the drug was effective in improving platelet counts (×10∧9/L) (mean differences (MD) = 163.421, 95% CI: 46.998-279.844) and lactate dehydrogenase levels (mean differences (MD) = 336.608 U/L, 95% CI: 164.816 U/L-508.399 U/L).

CONCLUSIONS

Based on the meta-analysis, treatment with eculizumab can reduce dialysis rates and improve patients' quality of life by enhancing renal function.

Targeting the Complement Pathway in Kidney Transplantation

The complement system is paramount in the clearance of pathogens and cell debris, yet is increasingly recognized as a key component in several pathways leading to allograft injury. There is thus a growing interest in new biomarkers to assess complement activation and guide tailored therapies after kidney transplantation (KTx). C5 blockade has revolutionized post-transplant management of atypical hemolytic uremic syndrome, a paradigm of complement-driven disease. Similarly, new drugs targeting the complement amplification loop hold much promise in the treatment and prevention of recurrence of C3 glomerulopathy. Although unduly activation of the complement pathway has been described after brain death and ischemia reperfusion, any clinical attempts to mitigate the ensuing renal insults have so far provided mixed results. However, the intervention timing, strategy, and type of complement blocker need to be optimized in these settings. Furthermore, the fast-moving field of ex vivo organ perfusion technology opens new avenues to deliver complement-targeted drugs to kidney allografts with limited iatrogenic risks. Complement plays also a key role in the pathogenesis of donor-specific ABO- and HLA-targeted alloantibodies. However, C5 blockade failed overall to improve outcomes in highly sensitized patients and prevent the progression to chronic antibody-mediated rejection (ABMR). Similarly, well-conducted studies with C1 inhibitors in sensitized recipients yielded disappointing results so far, in part, because of subtherapeutic dosage used in clinical studies. The emergence of new complement blockers raises hope to significantly reduce the negative effect of ischemia reperfusion, ABMR, and nephropathy recurrence on outcomes after KTx.

Early Eculizumab Withdrawal in Patients With Atypical Hemolytic Uremic Syndrome in Native Kidneys Is Safe and Cost-Effective: Results of the CUREiHUS Study

Introduction

The introduction of eculizumab has improved the outcome in patients with atypical hemolytic uremic syndrome (aHUS). The optimal treatment strategy is debated. Here, we report the results of the CUREiHUS study, a 4-year prospective, observational study monitoring unbiased eculizumab discontinuation in Dutch patients with aHUS after 3 months of therapy.

Methods

All pediatric and adult patients with aHUS in native kidneys and a first-time eculizumab treatment were evaluated. In addition, an extensive cost-consequence analysis was conducted.

Results

A total of 21 patients were included in the study from January 2016 to October 2020. In 17 patients (81%), a complement genetic variant or antibodies against factor H were identified. All patients showed full recovery of hematological thrombotic microangiopathy (TMA) parameters after the start of eculizumab. A renal response was noted in 18 patients. After a median treatment duration of 13.6 weeks (range 2.1-43.9), eculizumab was withdrawn in all patients. During follow-up (80.7 weeks [0.0-236.9]), relapses occurred in 4 patients. Median time to first relapse was 19.5 (14.3-53.6) weeks. Eculizumab was reinitiated within 24 hours in all relapsing patients. At last follow-up, there were no chronic sequelae, i.e., no clinically relevant increase in serum creatinine (sCr), proteinuria, and/or hypertension in relapsing patients. The low sample size and event rate did not allow to determine predictors of relapse. However, relapses only occurred in patients with a likely pathogenic variant. The cost-effectiveness analysis revealed that the total medical expenses of our population were only 30% of the fictive expenses that would have been made when patients received eculizumab every fortnight.

Conclusion

It is safe and cost-effective to discontinue eculizumab after 3 months of therapy in patients with aHUS in native kidneys. Larger data registries are needed to determine factors associated with suboptimal kidney function recovery during eculizumab treatment, factors to predict relapses, and long-term outcomes of eculizumab discontinuation.