Interventions for atypical haemolytic uraemic syndrome

Practical approach to thrombocytopenia in patients with sepsis: a narrative review

Thrombocytopenia frequently occurs in patients with sepsis. Disseminated intravascular coagulation (DIC) may be a possible cause of thrombocytopenia owing to its high prevalence and association with poor outcomes; however, it is important to keep the presence of other diseases in mind in sepsis practice. Thrombotic microangiopathy (TMA), which is characterized by thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (HUS), and complement-mediated HUS, is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. TMA has become widely recognized in recent years because of the development of specific treatments. Previous studies have reported a remarkably lower prevalence of TMA than DIC; however, its epidemiology is not well defined, and there may be cases in which TMA is not correctly diagnosed, resulting in poor outcomes. Therefore, it is important to differentiate DIC from TMA. Nevertheless, differentiating between DIC and TMA remains a challenge as indicated by previous reports that most patients with TMA can be diagnosed as DIC using the universal coagulation scoring system. Several algorithms to differentiate sepsis-related DIC from TMA have been suggested, contributing to improving the care of septic patients with thrombocytopenia; however, it may be difficult to apply these algorithms to patients with coexisting DIC and TMA, which has recently been reported. This review describes the disease characteristics, including epidemiology, pathophysiology, and treatment, of DIC, TMA, and other diseases with thrombocytopenia and proposes a novel practical approach flow, which is characterized by the initiation of the diagnosis of TMA in parallel with the diagnosis of DIC. This practical flow also refers to the longitudinal diagnosis and treatment flow with TMA in mind and real clinical timeframes. In conclusion, we aim to widely disseminate the results of this review that emphasize the importance of incorporating consideration of TMA in the management of septic DIC. We anticipate that this practical new approach for the diagnostic and treatment flow will lead to the appropriate diagnosis and treatment of complex cases, improve patient outcomes, and generate new epidemiological evidence regarding TMA.

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.

Eculizumab Versus Ravulizumab for the Treatment of Atypical Hemolytic Uremic Syndrome: A Systematic Review

Atypical hemolytic uremic syndrome (aHUS) is a type of thrombotic microangiopathy and is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. The complement cascade plays an integral role in aHUS. Mutations in the complement cascade, especially in the alternative pathway (AP) lead to an unregulated and continuous activation of the cascade. Eculizumab and ravulizumab are humanized monoclonal antibodies that inhibit the complement cascade. This systematic analysis reviews the evidence for both antibodies to compare them in terms of safety and efficacy. This review will also assess the evidence for biomarker associations with interventions, the role of genetic mutations in the prognosis of disease, and the financial burden of both treatment options. An in-depth search was conducted across PubMed, Science Direct, and Cochrane Library following the PRISMA 2020 guidelines. Both eculizumab and ravulizumab were comparable in safety and efficacy but ravulizumab was preferred by patients and their caregivers as it posed a lower financial burden and had less frequent dosing. Soluble complement 5b-9 (sC5b), especially in urine, has the potential to be used as a biomarker to assess response to treatment. Genetic mutations, especially mutations in complement factor I (CFI), membrane cofactor protein (MCP), and complement factor H (CFH), were associated with a higher risk of recurrence, and therefore care should be taken when attempting to discontinue treatment in this subset of patients. Treatment with a monoclonal antibody should be initiated as soon as a genetic mutation is identified. Blinded, double-arm, clinical trials preferably with larger sample sizes are needed to effectively compare both the monoclonal antibodies.

Complement Inhibitors in the Management of Complement-Mediated Hemolytic Uremic Syndrome and Paroxysmal Nocturnal Hemoglobinuria

BACKGROUND

Complement-mediated HUS (CM-HUS) and paroxysmal nocturnal hemoglobinuria (PNH) are rare hematologic disorders that cause dysregulation and hyperactivation of the complement system. Historically, treatment of CM-HUS involved plasma exchange (PLEX), often with limited benefit and variable tolerance. Conversely, PNH was treated with supportive care or hemopoietic stem cell transplant. Within the last decade, monoclonal antibody therapies that block terminal complement pathway activation, have emerged as less invasive and more efficacious options for management of both disorders. This manuscript seeks to discuss a relevant clinical case of CM-HUS and the evolving landscape of complement inhibitor therapies for CM-HUS and PNH.

AREAS OF UNCERTAINTY

Eculizumab, the first humanized anti-C5 monoclonal antibody, has been the standard of care in treating CM-HUS and PNH for over a decade. Although eculizumab has remained an effective agent, the variability in ease and frequency of administration has remained an obstacle for patients. The development of novel complement inhibitor therapies with longer half-lives, has allowed for changes in frequency and route of administration, thus improving patient QOL. However, there are limited prospective clinical trial data given disease rarity, and limited information on variable infusion frequency and length of treatment.

THERAPEUTIC ADVANCES

Recently, there has been a push to formulate complement inhibitors that improve QOL while maintaining efficacy. Ravulizumab, a derivative of eculizumab, was developed to allow for less frequent administration, while remaining efficacious. In addition, the novel oral and subcutaneous therapies, danicopan and crovalimab, respectively, along with pegcetacoplan are currently undergoing active clinical trials, and poised to further reduce treatment burden.

CONCLUSION

Complement inhibitor therapies have changed the treatment landscape for CM-HUS and PNH. With a significant emphasis on patient QOL, novel therapies continue to emerge and require an in-depth review of their appropriate use and efficacy in these rare disorders.

CLINICAL CASE

A 47-year-old woman with hypertension and hyperlipidemia presented with shortness of breath and was found to have hypertensive emergency in the setting of acute renal failure. Her serum creatinine was 13.9 mg/dL; elevated from 1.43 mg/dL 2 years before. The differential diagnosis for her acute kidney injury (AKI) included infectious, autoimmune, and hematologic processes. Infectious work-up was negative. ADAMTS13 activity level was not low at 72.9%, ruling out thrombotic thrombocytopenic purpura (TTP). Patient underwent a renal biopsy, which revealed acute on chronic thrombotic microangiopathy (TMA). A trial of eculizumab was initiated with concurrent hemodialysis. The diagnosis of CM-HUS was later confirmed by a heterozygous mutation in complement factor I (CFI), resulting in increased membrane attack complex (MAC) cascade activation. The patient was maintained on biweekly eculizumab and was eventually transitioned to ravulizumab infusions as an outpatient. Her renal failure did not recover, and the patient remains on hemodialysis while awaiting kidney transplantation.

Ravulizumab 100 mg/mL formulation reduces infusion time and frequency, improving the patient and caregiver experience in the treatment of atypical haemolytic uraemic syndrome

WHAT IS KNOWN AND OBJECTIVE

The C5 inhibitor eculizumab is the standard of care for treatment of atypical haemolytic uraemic syndrome (aHUS). Ravulizumab, a next-generation C5 inhibitor, was engineered to have a longer terminal half-life than eculizumab. We describe practical benefits of the advanced ravulizumab 100 mg/mL formulation.

COMMENT

Use of ravulizumab results in fewer maintenance infusions per year (25%-50%) compared with eculizumab. Maintenance infusion time of ravulizumab 100 mg/mL is 2-4 times shorter than ravulizumab 10 mg/mL in all weight cohorts and approximately half that of eculizumab for patients weighing <40 kg. Ravulizumab 100 mg/mL requires fewer vials annually than eculizumab in most weight cohorts.

WHAT IS NEW AND CONCLUSION

With ravulizumab 100 mg/mL, patients and caregivers experience fewer infusions per year and decreased annual infusion times, improving infusion experience. Infusion centres can expect corresponding decreases in resource utilization.

Tipping the balance: intricate roles of the complement system in disease and therapy

The ability of the complement system to rapidly and broadly react to microbial intruders, apoptotic cells and other threats by inducing forceful elimination responses is indispensable for its role as host defense and surveillance system. However, the danger sensing versatility of complement may come at a steep price for patients suffering from various immune, inflammatory, age-related, or biomaterial-induced conditions. Misguided recognition of cell debris or transplants, excessive activation by microbial or damaged host cells, autoimmune events, and dysregulation of the complement response may all induce effector functions that damage rather than protect host tissue. Although complement has long been associated with disease, the prevalence, impact and complexity of complement’s involvement in pathological processes is only now becoming fully recognized. While complement rarely constitutes the sole driver of disease, it acts as initiator, contributor, and/or exacerbator in numerous disorders. Identifying the factors that tip complement’s balance from protective to damaging effects in a particular disease continues to prove challenging. Fortunately, however, molecular insight into complement functions, improved disease models, and growing clinical experience has led to a greatly improved understanding of complement’s pathological side. The identification of novel complement-mediated indications and the clinical availability of the first therapeutic complement inhibitors has also sparked a renewed interest in developing complement-targeted drugs, which meanwhile led to new approvals and promising candidates in late-stage evaluation. More than a century after its description, complement now has truly reached the clinic and the recent developments hold great promise for diagnosis and therapy alike.

Serum C1q Levels Have Prognostic Value for Sepsis and are Related to the Severity of Sepsis and Organ Damage

Objective

To explore the clinical application value of serum complement component C1q levels in sepsis.

Methods

The clinical data and laboratory examination data of 320 research subjects (including 132 cases as sepsis group, 93 cases as nonsepsis group and 95 cases as control group) who were diagnosed and treated in Renmin Hospital of Wuhan University from July 2020 to March 2021 were collected. We compared the levels of each index among the three groups and further analyzed the C1q levels of different severity subgroups and different outcome subgroups of sepsis. Afterwards, we explored the correlation between C1q levels and SOFA score, organ damage indexes and coagulation indexes. Finally, the receiver operating characteristic curve (ROC) was used to analyze the prognostic value of C1q in patients with sepsis.

Results

C1q levels were significantly reduced in the serum of patients with sepsis; the level of C1q in the death group was lower than that in the survival group (127.1 mg/L vs 153.2 mg/L, P < 0.05), and the mortality in the C1q decreased group was higher when compared with C1q normal group; in addition, serum C1q levels were correlated with SOFA score, organ damage indexes and coagulation indexes; C1q had a high area under the curve (AUC) for the prognosis of sepsis, and the combination of other indexes can further improve the prognostic value.

Conclusion

Serum C1q levels have potential clinical value for the condition and prognosis of sepsis.

Interventions for atypical haemolytic uraemic syndrome

BACKGROUND

Atypical haemolytic uraemic syndrome (aHUS) is a rare disorder characterised by thrombocytopenia, microangiopathic haemolytic anaemia, and acute kidney injury. The condition is primarily caused by inherited or acquired dysregulation of complement regulatory proteins with ~40% of those affected aged < 18 years. Historically, kidney failure and death were common outcomes, however, improved understanding of the condition has led to discovery of novel therapies.

OBJECTIVES

To evaluate the benefits and harms of interventions for aHUS.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies for randomised controlled studies (RCTs) up to 3 September 2020 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. MEDLINE(OVID) 1946 to 27 July 2020 and EMBASE (OVID) 1974 to 27 July 2020 were searched for non-RCTs.

SELECTION CRITERIA

All randomised and non-randomised clinical trials comparing an intervention with placebo, an intervention with supportive therapy, or two or more interventions for aHUS were included. Given the rare nature of the condition in question, prospective single-arm studies of any intervention for aHUS were also included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted pre-specified data from eligible studies and evaluated risk of bias using a newly developed tool based on existing Cochrane criteria. As statistical meta-analysis was not appropriate, qualitative analysis of data was then performed.

MAIN RESULTS

We included five single-arm studies, all of which evaluated terminal complement inhibition for the treatment of aHUS. Four studies evaluated the short-acting C5 inhibitor eculizumab and one study evaluated the longer-acting C5 inhibitor ravulizumab. All included studies within the review were of non-randomised, single-arm design. Thus, risk of bias is high, and it is challenging to draw firm conclusions from this low-quality evidence. One hundred patients were included within three primary studies evaluating eculizumab, with further data reported from 37 patients in a secondary study. Fifty-eight patients were included in the ravulizumab study. After 26 weeks of eculizumab therapy there were no deaths and a 70% reduction in the number of patients requiring dialysis. Complete thrombotic microangiopathic (TMA) response was observed in 60% of patients at 26 weeks and 65% at two years. After 26 weeks of ravulizumab therapy four patients had died (7%) and complete TMA response was observed in 54% of patients. Substantial improvements were seen in estimated glomerular filtration rate and health-related quality of life in both eculizumab and ravulizumab studies. Serious adverse events occurred in 42% of patients, and meningococcal infection occurred in two patients, both treated with eculizumab.

AUTHORS' CONCLUSIONS

When compared with historical data, terminal complement inhibition appears to offer favourable outcomes in patients with aHUS, based upon very low-quality evidence drawn from five single-arm studies. It is unlikely that an RCT will be conducted in aHUS and therefore careful consideration of future single-arm data as well as longer term follow-up data will be required to better understand treatment duration, adverse outcomes and risk of disease recurrence associated with terminal complement inhibition.