Eculizumab in paroxysmal nocturnal haemoglobinuria and atypical haemolytic uraemic syndrome: 10-year pharmacovigilance analysis

Non-Plasmapheresis Approaches for Managing Severe Renal Thrombotic Microangiopathy: A Report of 7 Cases

C5-blockers are the established treatment for complement-mediated hemolytic uremic syndrome (CM-HUS). However, CM-HUS, lacking a definitive test, prompts plasma exchanges as a common first-line therapy, pending further assessments, despite complications and limited evidence in this indication. Recent experts' opinion endorses C5-blockers as the initial treatment for severe renal thrombotic microangiopathy (TMA). This retrospective, single center study reports a series of seven patients treated with a plasmapheresis-free approach. All patients presented with severe renal TMA symptoms and low French score and received prompt 900mg eculizumab within a median of 9 hours from admission. Hematological recovery was rapid, renal function improved in six patients within 6.5 days, with a median hospital stay of 16 days. No rescue plasmapheresis was used. We report seven cases of an early C5-blocker and plasmapheresis-free strategy in severe renal TMA suspicious for CM-HUS, demonstrating promising initial results. Clinical trials are needed to confirm the efficacy and safety of this approach. Addressing the high cost of C5-blocking therapies and exploring cost-effective alternatives is also crucial for broader implementation and accessibility in targeted therapies for adult renal TMA.

Complement system activation: bridging physiology, pathophysiology, and therapy

The complement system is a set of over 50 proteins that constitutes an essential part of the innate immune system. Complement system activation involves an organized proteolytic cascade. Overactivation of complement system activation is the main pathogenic mechanism of several diseases and contributes to the manifestations of many other conditions. This review describes the normal complement system and the role for complement dysregulation in critical illnesses, notably sepsis and acute respiratory distress syndrome. Complement activation is involved in the immune system response to pathogens but, when excessive, can contribute to tissue damage, runaway inflammation, and capillary leakage syndrome. Complement overactivation may play a key role in severe forms of coronavirus disease 2019 (COVID-19). Two diseases whose manifestations are mainly caused by complement overactivation, namely, atypical hemolytic and uremic syndrome (aHUS) and myasthenia gravis, are discussed. A diagnostic algorithm for aHUS is provided. Early complement-inhibiting therapy has been proven effective. When renal transplantation is required, complement-inhibiting drugs can be used prophylactically to prevent aHUS recurrence. Similarly, acetylcholine-receptor autoantibody-positive generalized myasthenia gravis involves complement system overactivation and responds to complement inhibition. The two main complement inhibitors used in to date routine are eculizumab and ravulizumab. The main adverse event is Neisseria infection, which is rare and preventable, but can be fatal. The complement system is crucial to health but, when overactivated, can cause or contribute to disease. Effective complement inhibitors are now available, although additional data are required to determine optimal regimens. Further research is also needed to better understand the complement system, develop advanced diagnostic tools, and identify markers that allow the personalization of treatment strategies.

Global aHUS Registry Analysis of Patients Switching to Ravulizumab From Eculizumab

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a progressive rare disease that, if untreated, can result in severe organ damage and death. Ravulizumab, a next-generation terminal complement inhibitor, provides immediate, complete, and sustained complement C5 inhibition. Real-world data in patients with aHUS who switched to ravulizumab from eculizumab are lacking.

Methods

The Global aHUS Registry is a multicenter study (NCT01522183) collecting data on adult or pediatric patients with an aHUS diagnosis, regardless of treatment. Patient characteristics, genetic data, hematological and renal parameters, clinical events (e.g., dialysis and kidney transplantation), and adverse events (AEs) were extracted from patients who switched to ravulizumab from eculizumab up to July 3, 2023.

Results

Overall, 60 patients switched to ravulizumab (adult: n = 43; pediatric: n = 17); 11 patients were excluded from effectiveness and genetic analyses (N = 49; adult: n = 40; pediatric: n = 9) because they received <3 months ravulizumab treatment and/or had >1 month between eculizumab discontinuation and ravulizumab initiation. Pathogenic complement variants were identified in 11 of 49 patients (22%); the most common was a complement factor H variant (n = 5/49 [10%]). During ravulizumab treatment, 20 AEs occurred in 13 patients, with no unexpected AEs and only 3 treatment-related AEs (infusion reaction, headaches, and fatigue). No meningococcal infections or deaths were reported. No new events of dialysis, kidney transplantation, or thrombotic microangiopathy were reported. Renal and hematological parameters remained stable after switching to ravulizumab.

Conclusion

This is the first real-world cohort analysis of data from patients treated with ravulizumab and reinforces the real-world safety and effectiveness data of ravulizumab in patients with aHUS who switched from eculizumab.

Reproductive Health in Kidney Transplant Recipients

Increasing number of women with kidney transplants are of reproductive age and desire successful pregnancies. Successful outcomes of pregnancy can be achieved with preconception counseling, education about contraception use, the timing of pregnancy (delaying by first year post-transplant), and the choice of immunosuppression medication. Ensuring stable renal function including optimized creatinine, proteinuria, and blood pressure increases successful outcomes. Pregnancy with kidney transplant has an increased risk of preeclampsia, gestational diabetes militeus, cesarean section, and preterm delivery. Multidisciplinary cooperation with high-risk obstetrics and transplant nephrologists is vital.

The efficacy and safety of eculizumab in patients and the role of C5 polymorphisms

Eculizumab is an orphan drug with indications for extremely rare autoimmune disorders. It is primarily prescribed for use in patients with paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome; but is also highly effective in the treatment of myasthenia gravis, among others. By binding to the C5 protein in the complement system, eculizumab effectively inhibits cellular hemolysis and autoimmune reactions. Despite this effective treatment, some patients reported no improvement in symptoms. Genetic sequencing revealed three distinct C5 mutations in the non-responders and these polymorphisms appeared to be most prevalent among Japanese, Korean and African populations. Here, we present an overview of the current and potential future applications of eculizumab, as well as the disadvantages of eculizumab treatment in patients with C5 polymorphisms.

Immunodeficiency: Complement disorders

The complement system is an important component of innate and adaptive immunity that consists of three activation pathways. The classic complement pathway plays a role in humoral immunity, whereas the alternative and lectin pathways augment the innate response. Impairment, deficiency, or overactivation of any of the known 50 complement proteins may lead to increased susceptibility to infection with encapsulated organisms, autoimmunity, hereditary angioedema, or thrombosis, depending on the affected protein. Classic pathway defects result from deficiencies of complement proteins C1q, C1r, C1s, C2, and C4, and typically manifest with features of systemic lupus erythematosus and infections with encapsulated organisms. Alternative pathway defects due to deficiencies of factor B, factor D, and properdin may present with increased susceptibility to Neisseria infections. Lectin pathway defects, including Mannose-binding protein-associated serine protease 2 (MASP2) and ficolin 3, may be asymptomatic or lead to pyogenic infections and autoimmunity. Complement protein C3 is common to all pathways, deficiency of which predisposes patients to severe frequent infections and glomerulonephritis. Deficiencies in factor H and factor I, which regulate the alternative pathway, may lead to hemolytic uremic syndrome. Disseminated Neisseria infections result from terminal pathway defects (i.e., C5, C6, C7, C8, and C9). Diagnosis of complement deficiencies involves screening with functional assays (i.e., total complement activity [CH50], alternative complement pathway activity [AH50], enzyme-linked immunosorbent assay [ELISA]) followed by measurement of individual complement factors by immunoassay. Management of complement deficiencies requires a comprehensive and individualized approach with special attention to vaccination against encapsulated bacteria, consideration of prophylactic antibiotics, treatment of comorbid autoimmunity, and close surveillance.

Navigating the Complement Pathway to Optimize PNH Treatment with Pegcetacoplan and Other Currently Approved Complement Inhibitors

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare and potentially life-threatening hematologic disorder caused by a somatic mutation in a relevant portion of hematopoietic stem cells. Mutation of the phosphatidylinositol glycan biosynthesis class A (PIGA) gene prevents the expression of cell-surface proteins, including the complement regulatory proteins CD55 and CD59. With decreased or a lack of CD55 and CD59 expression on their membranes, PNH red blood cells become susceptible to complement-mediated hemolysis (symptoms of which include anemia, dysphagia, abdominal pain, and fatigue), leading to thrombosis. State-of-the-art PNH treatments act by inhibiting the dysregulated complement at distinct points in the activation pathway: late at the C5 level (C5 inhibitors, eculizumab, ravulizumab, and crovalimab), centrally at the C3 level (C3/C3b inhibitors and pegcetacoplan), and early at the initiation and amplification of the alternative pathway (factor B inhibitor, iptacopan; factor D inhibitor, danicopan). Through their differing mechanisms of action, these treatments elicit varying profiles of disease control and offer valuable insights into the molecular underpinnings of PNH. This narrative review provides an overview of the mechanisms of action of the six complement inhibitors currently approved for PNH, with a focus on the C3/C3b-targeted therapy, pegcetacoplan.

The complement system: A key player in the host response to infections

Infections are one of the most significant healthcare and economic burdens across the world as underscored by the recent coronavirus pandemic. Moreover, with the increasing incidence of antimicrobial resistance, there is an urgent need to better understand host-pathogen interactions to design effective treatment strategies. The complement system is a key arsenal of the host defense response to pathogens and bridges both innate and adaptive immunity. However, in the contest between pathogens and host defense mechanisms, the host is not always victorious. Pathogens have evolved several approaches, including co-opting the host complement regulators to evade complement-mediated killing. Furthermore, deficiencies in the complement proteins, both genetic and therapeutic, can lead to an inefficient complement-mediated pathogen eradication, rendering the host more susceptible to certain infections. On the other hand, overwhelming infection can provoke fulminant complement activation with uncontrolled inflammation and potentially fatal tissue and organ damage. This review presents an overview of critical aspects of the complement-pathogen interactions during infection and discusses perspectives on designing therapies to mitigate complement dysfunction and limit tissue injury.

Recommendations for the management of myasthenia gravis in Belgium

International guidelines on the treatment of myasthenia gravis (MG) have been published but are not tailored to the Belgian situation. This publication presents recommendations from a group of Belgian MG experts for the practical management of MG in Belgium. It includes recommendations for treatment of adult patients with generalized myasthenia gravis (gMG) or ocular myasthenia gravis (oMG). Depending on the MG-related antibody a treatment sequence is suggested with therapies that can be added on if the treatment goal is not achieved. Selection of treatments was based on the level of evidence of efficacy, registration and reimbursement status in Belgium, common daily practice and the personal views and experiences of the authors. The paper reflects the situation in February 2024. In addition to the treatment considerations, other relevant aspects in the management of MG are addressed, including comorbidities, drugs aggravating disease symptoms, pregnancy, and vaccination. As many new treatments might potentially come to market, a realistic future perspective on the impact of these treatments on clinical practice is given. In conclusion, these recommendations intend to be a guide for neurologists treating patients with MG in Belgium.

Ravulizumab in Atypical Hemolytic Uremic Syndrome: An Analysis of 2-Year Efficacy and Safety Outcomes in 2 Phase 3 Trials

Rationale & Objective

Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) caused by complement dysregulation. Ravulizumab is a C5i approved for the treatment of aHUS. This analysis assessed long-term outcomes of ravulizumab in adults and pediatric patients with aHUS.

Study Design

This analysis reports 2-year data from 2 phase 3, single-arm studies.

Setting & Participants

One study included C5i-naïve adults (NCT02949128), and the other included 2 cohorts of pediatric patients (C5i-naïve and those who switched to ravulizumab from eculizumab [pediatric switch patients]; NCT03131219).

Exposure

Patients received intravenous ravulizumab every 4-8 weeks, with the dose depending on body weight.

Outcomes

The primary endpoint in the studies of C5i-naïve patients was complete TMA response, which consisted of platelet count normalization, lactate dehydrogenase normalization, and ≥25% improvement in serum creatinine concentrations from baseline, at 2 consecutive assessments ≥4 weeks apart.

Analytical Approach

All analyses used descriptive statistics. No formal statistical comparisons were performed.

Results

In total, 86 and 92 patients were included in efficacy and safety analyses, respectively. Complete TMA response rates over 2 years were 61% and 90% in C5i-naïve adults and pediatric patients, respectively. The median increase in estimated glomerular filtration rate from baseline was maintained over 2 years in C5i-naïve adults (35 mL/min/1.73 m2) and pediatric patients (82.5 mL/min/1.73 m2). Most adverse events and serious adverse events occurred during the first 26 weeks. No meningococcal infections were reported. Improvement in the Functional Assessment of Chronic Illness Therapy - Fatigue score achieved by 26 weeks was maintained over 2 years.

Limitations

Limitations were the small sample of pediatric switch patients and limited availability of genetic data.

Conclusions

Long-term treatment with ravulizumab is well tolerated and associated with improved hematologic and renal parameters and quality of life in adults and pediatric patients with aHUS.

Apical tubular complement activation and the loss of kidney function in proteinuric kidney diseases

Many kidney diseases are associated with proteinuria. Since proteinuria is independently associated with kidney function loss, anti-proteinuric medication, often in combination with dietary salt restriction, comprises a major cornerstone in the prevention of progressive kidney failure. Nevertheless, complete remission of proteinuria is very difficult to achieve, and most patients with persistent proteinuria slowly progress toward kidney failure. It is well-recognized that proteinuria leads to kidney inflammation and fibrosis via various mechanisms. Among others, complement activation at the apical side of the proximal tubular epithelial cells is suggested to play a crucial role as a cause of progressive loss of kidney function. However, hitherto limited attention is given to the pathophysiological role of tubular complement activation relative to glomerular complement activation. This review aims to summarize the evidence for tubular epithelial complement activation in proteinuric kidney diseases in relation to loss of kidney function.

You shall not pass: how complement C5 mediated antifungal immunity blocks systemic candidiasis and preserves renal tissue barriers

The rising prevalence of fungal infections is a significant and growing public health threat, and this risk is further underscored by our incomplete understanding of why organs like the kidney are so susceptible to systemic candidiasis. To combat the high mortality of such infections, we urgently need to advance our understanding of fungal pathogenesis and how it articulates with human immune response. Now, a recent landmark study has illuminated a crucial role of the complement system in the response to candidiasis and determined the stepwise local response of phagocytes within the kidney during infection. These fundamental discoveries provide crucial insights that can be leveraged to improve the care and outcome for patients with fungal infections.

Eculizumab for adult patients with atypical haemolytic-uraemic syndrome: full dataset analysis of Japanese post-marketing surveillance

BACKGROUND

Eculizumab has been approved for atypical haemolytic-uraemic syndrome (aHUS) in Japan since 2013. Post-marketing surveillance enrolled patients with aHUS who received ≥ 1 dose of eculizumab to assess eculizumab safety and effectiveness.

METHODS

We evaluated serious adverse events and effectiveness endpoints, i.e., haematologic normalization, a decrease of ≥ 25% in serum creatinine (sCr) levels, and complete thrombotic microangiopathy (TMA) response in adult patients with aHUS without other underlying diseases. In addition, the difference of baseline characteristics between patients who did and did not meet effectiveness endpoints was examined.

RESULTS

In this safety and effectiveness analysis, 79 adult patients were included; median age was 54.0 years, median treatment duration was 30 weeks. Total exposure time of eculizumab was 75.51 patient-years, and 94 serious adverse events were reported in 39 patients. No unexpected safety signals were identified in this population. Mean platelet count, lactate dehydrogenase and estimated glomerular filtration rate significantly improved after 7 days of treatment. Complete TMA response, haematologic normalization and the improvement of sCr levels were met by 35.3%, 40.4% and 51.3% of patients, respectively. Median treatment duration was shorter in patients who did not achieve complete TMA response (6 weeks) than in patients who did (114 weeks). Multivariate analysis suggested that the time from the most recent TMA episode to start of eculizumab treatment was negatively associated with kidney function improvement.

CONCLUSIONS

No unexpected safety signals of eculizumab were identified in Japanese patients with aHUS in a real-world setting. Renal outcomes were negatively associated with the time from the most recent TMA episode to the initiation of eculizumab treatment.

Enhancing prognostic prediction of invasive candidiasis among cancer patients with a serum C5a-based scoring model

PURPOSE

Invasive candidiasis poses a life-threatening risk, and early prognosis assessment is vital for timely interventions to reduce mortality. Serum C5a levels have recently been linked to prognosis, but confirmation in cancer patients is pending.

METHODS

We detected the concentrations of serum C5a in hospitalized cancer patients with invasive candidiasis from 2020 to 2023, and retrospectively analyzed the clinical data.

RESULTS

372 cases were included in this study, with a 90-day mortality rate of 21.8%. Candida albicans (48.7%) remained the predominant pathogen, followed by Candida glabrata (25.5%), Candida tropicalis (12.4%), and Candida parapsilosis (8.3%). Gastrointestinal cancer was the most diagnosed pathology type (37.6%). Serum C5a demonstrated a noteworthy correlation with 90-day mortality, and employing a cutoff value of 36.7 ng/ml revealed significantly higher 90-day mortality in low-C5a patients (41.2%) compared to high-C5a patients (6.3%) (p < 0.001). We also identified no source control, no surgery, metastasis, or chronic renal failure independently correlated with the 90-day mortality. Based on this, a prognostic model combining C5a and clinical parameters was constructed, which performed better than models built solely on C5a or clinical parameters. Furthermore, we weighted scores to each parameter in the model and presented diagnostic sensitivity and specificity corresponding to different score points calculated by the model.

CONCLUSION

We constructed a prognostic scoring model including serum C5a and clinical parameters, which would contribute to precise prognosis assessment and benefit the outcome among cancer patients.

Moss-produced human complement factor H with modified glycans has an extended half-life and improved biological activity

Most drugs that target the complement system are designed to inhibit the complement pathway at either the proximal or terminal levels. The use of a natural complement regulator such as factor H (FH) could provide a superior treatment option by restoring the balance of an overactive complement system while preserving its normal physiological functions. Until now, the systemic treatment of complement-associated disorders with FH has been deemed unfeasible, primarily due to high production costs, risks related to FH purified from donors' blood, and the challenging expression of recombinant FH in different host systems. We recently demonstrated that a moss-based expression system can produce high yields of properly folded, fully functional, recombinant FH. However, the half-life of the initial variant (CPV-101) was relatively short. Here we show that the same polypeptide with modified glycosylation (CPV-104) achieves a pharmacokinetic profile comparable to that of native FH derived from human serum. The treatment of FH-deficient mice with CPV-104 significantly improved important efficacy parameters such as the normalization of serum C3 levels and the rapid degradation of C3 deposits in the kidney compared to treatment with CPV-101. Furthermore, CPV-104 showed comparable functionality to serum-derived FH in vitro, as well as similar performance in ex vivo assays involving samples from patients with atypical hemolytic uremic syndrome, C3 glomerulopathy and paroxysomal nocturnal hematuria. CPV-104 - the human FH analog expressed in moss - will therefore allow the treatment of complement-associated human diseases by rebalancing instead of inhibiting the complement cascade.

Eculizumab for paroxysmal nocturnal hemoglobinuria: Two cases of successful pregnancy outcomes

Paroxysmal nocturnal hemoglobinuria is a rare disease with the incidence ranging from 0.08 to 0.57 per 100,000 person-years. Up to 25% of cases in women are detected during pregnancy. We report two cases of successful pregnancy outcomes in patients treated with eculizumab, pointing out the importance of interdisciplinary approach in these high-risk pregnancies.

Newly emerging type B insulin resistance (TBIR) during treatment with eculizumab for AQP4-IgG-positive neuromyelitis optica spectrum disorder (NMOSD): fatal outcome

BACKGROUND

Aquaporin-4 immunoglobulin G (AQP4-IgG) antibody-positive neuromyelitis optica spectrum disorders (NMOSD) are frequently associated with other autoimmune disorders, including systemic lupus erythematosus (SLE). Eculizumab (ECU) is a highly effective long-term treatment for NMOSD. However, ECU is known to increase significantly the risk of infection with encapsulated bacteria and sepsis. Recently, increased insulin resistance (IR) in patients with NMOSD has been suggested. Type B IR (TBIR) is a rare autoimmune condition often accompanying or preceding SLE. TBIR has not yet been reported in NMOSD.

OBJECTIVE

To report an ECU-treated patient with AQP4-IgG-positive NMOSD who developed fatal septic complications after the emergence of TBIR.

METHODS

Description of the clinical course over a period of 8 years.

RESULTS

A female patient was diagnosed with NMOSD at the age of 16 years. A variety of disease-modifying drugs failed to achieve sufficient disease control, resulting in severe tetraparesis. Treatment with ECU was started 6 years after NMOSD diagnosis and stabilized the disease. The patient developed TBIR 8 months after initiation of ECU therapy. Following high-dose intravenous methylprednisolone therapy for a clinical relapse and three further courses of ECU, the patient was admitted with severe pneumonia caused by the encapsulated bacterium Klebsiella pneumoniae and hypoglycemia. Despite multimodal therapy, the patient died from sepsis-related multiorgan failure 18 months after initiation of ECU.

CONCLUSIONS

TBIR should be considered as differential diagnosis in patients with NMOSD presenting with disturbed glucose metabolism, irrespective of the presence of SLE. More real-world data are needed on the risk/benefit ratio of ECU treatment in patients who have co-existing autoimmune comorbidities that may compromise immune function. Strategies to mitigate the risk of serious infection in patients treated with ECU are discussed.

Balancing efficacy and safety of complement inhibitors

Complement inhibitors have been approved for several immune-mediated diseases and they are considered the next paradigm-shifting approach in the treatment of glomerulonephritis. The hierarchical organization of the complement system offers numerous molecular targets for therapeutic intervention. However, complement is an integral element of host defense and therefore complement inhibition can be associated with serious infectious complications. Here we give a closer look to the hierarchical complement system and how interfering with proximal versus distal or selective versus unselective molecular targets could determine efficacy and safety. Furthermore, we propose to consider the type of disease, immunological activity, and patient immunocompetence when stratifying patients, e.g., proximal/unselective targets for highly active and potentially fatal diseases while distal and selective targets may suit more chronic disease conditions with low or moderate disease activity requiring persistent complement blockade in patients with concomitant immunodeficiency. Certainly, there exists substantial promise for anti-complement therapeutics. However, balancing efficacy and safety will be key to establish powerful treatment effects with minimal adverse events, especially when complement blockade is continued over longer periods of time in chronic disorders.

Thrombosis and meningococcal infection rates in pegcetacoplan-treated patients with paroxysmal nocturnal hemoglobinuria in the clinical trial and postmarketing settings

Background

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hematologic disease characterized by complement-mediated hemolysis and thrombosis. Complement component 5 (C5) inhibitors have decreased PNH-related thrombosis rates and reduced mortality compared with those of age-matched controls. A small but significantly increased risk of life-threatening Neisseria infections, especially N meningitidis, represents a long-term safety risk of complement inhibition.

Objectives

To evaluate the rates of thrombosis and meningococcal infections in patients with PNH treated with the complement component 3-targeted therapy pegcetacoplan.

Methods

Cumulative patient-year exposure to pegcetacoplan was calculated, and thrombotic events and meningococcal infections were reviewed in 7 clinical trials and in the postmarketing setting. The clinical trial protocols and pegcetacoplan labeling required vaccination against Streptococcus pneumoniae, N meningitidis, and Haemophilus influenzae before pegcetacoplan use; the label allowed for prophylactic antibiotic use if pegcetacoplan must be administered before vaccination.

Results

As of November 13, 2022, 464 patients with PNH had 619.4 patient-years of pegcetacoplan exposure in completed/ongoing clinical trials and the postmarketing setting. Seven thrombotic events were reported: 5 in clinical trials (2 in the same patient) and 2 in the postmarketing setting. The overall thrombosis rate was 1.13 events per 100 patient-years (clinical trials: 1.22 events/100 patient-years in 409.4 years; postmarketing: 0.95 events/100 patient-years in 210.0 years). No infections with meningococcal bacteria were reported.

Conclusion

Event rates for thrombosis were comparable between pegcetacoplan and previously reported rates of C5 inhibitors in patients with PNH, and no cases of meningococcal infection were reported with pegcetacoplan. Continued follow-up is required.

Successful Management of Atypical Hemolytic-Uremic Syndrome in Pregnancy Using Eculizumab: A Case Review

Hemolytic-uremic syndrome (HUS) is a rare thrombotic microangiopathy characterized by the triad of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury. The disease is pathologically marked by fibrinoid necrosis within renal arterioles and glomerular capillaries. HUS can be categorized into typical variants, often linked to Shiga toxin-producing Escherichia coli (STEC) infection, and atypical variants that stem from dysregulation in the alternative complement pathway. Pregnancy is a recognized predisposing condition for HUS due to the potential reduction in complement regulatory proteins and the possibility of heightened maternal immune response. This report illustrates the case of a 36-year-old woman who, at 36 weeks of gestation, faced a breech presentation and was diagnosed with atypical HUS (aHUS) after placental abruption. Following a cesarean section, she developed complications, including a pelvic hematoma and bilateral hydronephrosis. Despite initial suboptimal response to plasmapheresis, the patient exhibited marked clinical improvement with eculizumab treatment, with no evidence of disease relapse.

Rational design of antibody-like peptides for targeting the human complement fragment protein C5a

Human complement fragment 5a (C5a) is one of the most potent glycoproteins generated downstream of C3a and C4a during late-stage activation of the complement signaling cascade. C5a recruits receptors like C5aR1 and C5aR2 and is established to play a critical role in complement-mediated inflammation. Thus, excessive C5a in the plasma due to aberrant activation of the complement contributes to the pathophysiology of several chronic inflammatory diseases. Therefore, restricting the excessive interaction of C5a with its receptors by neutralizing C5a has been one of the most effective therapeutic strategies for the management of inflammatory diseases. Indeed, antibodies targeting C5 (Eculizumab), the precursor of C5a, and C5a (Vilobelimab) have already been approved by the FDA. Still, small designer peptides that work like antibodies and can target and stop C5a from interacting with its receptors seem to be a possible therapeutic alternative to antibodies because they are smaller, cheaper to make, more specific to their target, and can get through membrane barriers. As a proof-of-principle, the current study describes the computational design and evaluation of a pair of peptides that are able to form stable high-affinity complexes with the epitope regions of C5a that are important for the recruitment of C5aR1 and C5aR2. The computational data further supports the potential of designer peptides for mimicking the function of antibodies targeting C5a. However, further experimental studies will be required to establish the structure-function relationship of the designer peptides and also to establish the hypothesis of antibody-like peptides targeting C5a.

Safety Profile of Monoclonal Antibodies and Subsequent Drug Developments in the Treatment of Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disease characterized by intravascular hemolysis due to the targeting of affected red blood cells by the complement system. Eculizumab and ravulizumab are two monoclonal antibodies that inhibit the complement system's components and have been shown to significantly improve survival and quality of life. This review describes the role of these monoclonal antibodies in the treatment of PNH with an emphasis on their safety profile. The challenges in the use of these drugs and new drugs in various stages of drug development are also described, which may be helpful in addressing some of these challenges.

Risks and outcomes of pregnancy in neuromyelitis optica spectrum disorder: A comprehensive review

Neuromyelitis optica spectrum disorder (NMOSD) is a rare central nervous system autoimmune disease. Aquaporin-4 antibody (AQP4-IgG) is present in over 75% of cases and criteria also exist for the diagnosis of seronegative NMOSD. AQP4-IgG NMOSD has a strong female predominance (9:1 ratio), with a median onset age of 40 years. Pregnancy in those with NMOSD is therefore an important topic. Fecundity in NMOSD is likely impaired, and for females who conceive, obstetric complications including miscarriages and pre-eclampsia are significantly higher in NMOSD compared to the general population and in related conditions such as multiple sclerosis (MS). In contrast to MS, NMOSD disease activity does not subside during pregnancy. Also, relapse risk substantially rises above pre-pregnancy rates in the early postpartum period. In view of the evolving landscape of NMOSD, we provide a contemporary update of the impacts of pregnancy in NMOSD.

Real-life study to assess effectiveness and safety of eculizumab in patients with neuromyelitis optica spectrum disorders in France: protocol for ECUP4, an observational study

Background

Eculizumab, a humanized monoclonal antibody targeting the C5 complement protein, has been approved for the treatment of neuromyelitis optica spectrum disorders (NMOSD) in adult patients who are anti-aquaporin-4 (AQP4) antibody positive (Ab+). The aim of this study is to evaluate the long-term effectiveness and safety of eculizumab in French adults with NMOSD and to describe patients' characteristics, disability, and quality of life using data collected in a real-world setting.

Methods

This is the protocol for ECUP4, an ongoing prospective, observational, non-comparative, multicenter study conducted in 32 reference centers in France. Eligible patients must also be enrolled in NOMADMUS, a nested cohort of the French national multiple sclerosis registry (OFSEP). The primary endpoint is the annualized relapse rate. Secondary endpoints include the long-term safety of eculizumab, as well as patients' characteristics, treatment outcomes, disability, pain, visual acuity, and quality of life. Visits and treatments follow routine clinical practice. The case report forms (CRF) comprise data recorded in the context of the NOMADMUS cohort, collected during routine visits. The inclusion period is planned for 3 years, with no limitation on the number of patients enrolled. The maximum follow-up duration will be 5.5 years.

Conclusion

The efficacy and safety of eculizumab in patients with AQP4+ NMOSD have been demonstrated in randomized clinical trials that showed a significant reduction in the risk of relapse, with a safety profile consistent with other indications. This study will provide clinical and patient-reported evidence of the benefits of eculizumab, using data from a real-world setting in France.

Trial registration number

This study is registered at the French public repertory Health data Hub, N° F20211228123801. All information can be accessed at: https://www.health-data-hub.fr/.

Monoclonal antibody therapies for aquaporin-4-immunoglobulin G-positive neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease

Monoclonal antibody therapies mark the new era of targeted treatment for relapse prevention in aquaporin-4 (AQP4)-immunoglobulin G (IgG)-positive neuromyelitis optica spectrum disorder (AQP4-IgG+NMOSD). For over a decade, rituximab, an anti-CD20 B-cell-depleting agent, had been the most effectiveness treatment for AQP4-IgG+NMOSD. Tocilizumab, an anti-interleukin-6 receptor, was also observed to be effective. In 2019, several randomized, placebo-controlled trials were completed that demonstrated the remarkable efficacy of eculizumab (anti-C5 complement inhibitor), inebilizumab (anti-CD19 B-cell-depleting agent), and satralizumab (anti-interleukin-6 receptor), leading to the Food and Drug Administration (FDA) approval of specific treatments for AQP4-IgG+NMOSD for the first time. Most recently, ravulizumab (anti-C5 complement inhibitor) was also shown to be highly efficacious in an open-label, external-controlled trial. Although only some patients with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) warrant immunotherapy, there is currently no FDA-approved treatment for relapse prevention in MOGAD. Observational studies showed that tocilizumab was associated with a decrease in relapses, whereas rituximab seemed to have less robust effectiveness in MOGAD compared to AQP4-IgG+NMOSD. Herein, we review the evidence on the efficacy and safety of each monoclonal antibody therapy used in AQP4-IgG+NMOSD and MOGAD, including special considerations in children and women of childbearing potential.

Retinal Vasculitis After Intravitreal Pegcetacoplan: Report From the ASRS Research and Safety in Therapeutics (ReST) Committee

Purpose: To analyze post-marketing cases of retinal vasculitis after intravitreal pegcetacoplan. Methods: The American Society of Retina Specialists (ASRS) Research and Safety in Therapeutics (ReST) Committee as well as an expert panel performed a retrospective review of cases of retinal vasculitis reported to the ASRS. Clinical and imaging characteristics were reviewed for evidence of retinal vasculitis and analyzed. Results: Fourteen eyes of 13 patients were confirmed to have retinal vasculitis by review of imaging studies. All cases occurred after the first pegcetacoplan injection. Occlusive retinal vasculopathy was confirmed in 11 eyes (79%). Patients presented a median of 10.5 days (range, 8-23 days) after pegcetacoplan injection. All eyes had anterior chamber inflammation, and 12 eyes (86%) had vitritis. Vasculopathy involved retinal veins (100%) more than arteries (73%), and 12 eyes (86%) had retinal hemorrhages. The median visual acuity (VA) was 20/60 (range, 20/30-5/200) at baseline, 20/300 (range, 20/100-no light perception [NLP]) at vasculitis presentation, and 20/200 (range 20/70-NLP) at the last follow-up. Eight eyes (57%) had more than a 3-line decrease in VA, and 6 eyes (43%) had more than a 6-line decrease in VA from baseline to the final follow-up, including 2 eyes that were enucleated. Six eyes (43%) developed signs of anterior segment neovascularization. Conclusions: There is currently no known etiology for vasculitis in this series. Optimum treatment strategies remain unknown. Infectious etiologies should be considered, and corticosteroid treatments may hasten resolution of inflammatory findings. Continued treatment of affected patients with pegcetacoplan should be avoided.

Complement terminal pathway inhibition reduces peritoneal injuries in a rat peritonitis model

Peritonitis and the resulting peritoneal injuries are common problems that prevent long-term peritoneal dialysis (PD) therapy in patients with end-stage kidney diseases. Previously, we have analyzed the relationship between the complement system and progression of peritoneal injuries associated with PD, particularly focusing on the early activation pathways and effects of the anaphylatoxins. We here utilized a novel mAb 2H2 that blocks assembly of the membrane attack complex (MAC) to investigate roles of the complement terminal pathway in PD-associated peritoneal injury. We intraperitoneally injected mAb 2H2 anti-C5b-7 (2.5 or 5 mg/rat) once or twice over the five-day course of the experiment to investigate the effects of inhibiting formation of MAC in a fungal rat peritonitis model caused by repeated intraperitoneal administration of zymosan after methylglyoxal pretreatment (Zy/MGO model). Rats were sacrificed on day 5 and macroscopic changes in both parietal and visceral peritoneum evaluated. Peritoneal thickness, the abundance of fibrinogen and complement C3 and MAC deposition in tissue and accumulation of inflammatory cells were pathologically assessed. The results showed that mAb 2H2, but not isotype control mAb, reduced peritoneal thickness and accumulation of inflammatory cells in a dose and frequency-dependent manner in the Zy/MGO model. These effects were accompanied by decreased C3, MAC, and fibrinogen deposition in peritoneum. In conclusion, in the rat Zy/MGO model, complement terminal pathway activation and MAC formation substantially contributed to development of peritoneal injuries, suggesting that MAC-targeted therapies might be effective in preventing development of peritoneal injuries in humans.

Addition of danicopan to ravulizumab or eculizumab in patients with paroxysmal nocturnal haemoglobinuria and clinically significant extravascular haemolysis (ALPHA): a double-blind, randomised, phase 3 trial

BACKGROUND

Symptoms of anaemia due to clinically significant extravascular haemolysis can affect patients with paroxysmal nocturnal haemoglobinuria (PNH) treated with C5 inhibitors (ravulizumab or eculizumab). The aim of this study was to assess the efficacy and safety of danicopan (ALXN2040), an investigational, first-in-class, oral complement factor D inhibitor, as add-on therapy to ravulizumab or eculizumab in patients with PNH and clinically significant extravascular haemolysis.

METHODS

ALPHA is an ongoing, international, phase 3, randomised, double-blind, placebo-controlled trial evaluating danicopan as add-on therapy to ravulizumab or eculizumab. Eligible patients were adults (age ≥18 years) with PNH and clinically significant extravascular haemolysis (haemoglobin ≤9·5 g/dL; absolute reticulocyte count ≥120 × 109/L) on ravulizumab or eculizumab for at least 6 months. Patients were randomly assigned (2:1) to danicopan or placebo added to ravulizumab or eculizumab for 12 weeks using an interactive response technology system. Randomisation was stratified based on transfusion history, haemoglobin, and patients enrolled from Japan. The initial oral danicopan dose was 150 mg three times a day; escalation to 200 mg three times a day was permitted based on clinical response. The infusion dose level of eculizumab (every 2 weeks) ranged from 900 mg to 1500 mg, and for ravulizumab (monthly or every 8 weeks) ranged from 3000 mg to 3600 mg. The primary endpoint was change in haemoglobin concentration from baseline to week 12. Here we present the protocol-prespecified interim analysis, planned when approximately 75% of participants were randomly assigned to treatment and completed or discontinued at 12 weeks. This trial is registered with ClinicalTrials.gov (NCT04469465).

FINDINGS

Individuals were randomly assigned between Dec 16, 2020, and Aug 29, 2022. At data cutoff (June 28, 2022), 73 individuals were randomly assigned, received treatment, and were analysed for safety (danicopan, n=49; placebo, n=24). The protocol-prespecified interim efficacy analysis set included the first 63 participants (danicopan, n=42; placebo, n=21). At week 12, danicopan plus ravulizumab or eculizumab increased haemoglobin versus placebo plus ravulizumab or eculizumab (least squares mean [LSM] change from baseline: danicopan, 2·94 g/dL [95% CI 2·52 to 3·36]; placebo, 0·50 g/dL [-0·13 to 1·12]; LSM difference, 2·44 g/dL [1·69 to 3·20]; p<0·0001). Grade 3 adverse events in the danicopan group were increased alanine aminotransferase (two [4%] of 49 patients), leukopenia (one [2%]), neutropenia (two [4%]), cholecystitis (one [2%]), COVID-19 (one [2%]), increased aspartate aminotransferase (one [2%]), and increased blood pressure (one [2%]), and in the placebo group were anaemia (one [4%] of 24 patients), thrombocytopenia (one [4%]), and asthenia (one [4%]). The serious adverse events reported in the danicopan group were cholecystitis (one [2%] patient) and COVID-19 (one [2%]) and in the placebo group were anaemia and abdominal pain, both in one (4%) patient. There were no serious adverse events related to study drug or deaths reported in the study.

INTERPRETATION

These primary efficacy and safety results show that danicopan as add-on treatment to ravulizumab or eculizumab significantly improved haemoglobin concentrations at week 12 with no new safety concerns, suggesting an improved benefit-risk profile in patients with PNH and clinically significant extravascular haemolysis.

FUNDING

Alexion, AstraZeneca Rare Disease.

Beyond the usual suspects: Reviewing infections caused by typically-commensal Neisseria species

OBJECTIVE

Few data outside of individual case reports are available on non-meningococcal, non-gonococcal species of Neisseria as causative agents of invasive disease. This review collates disease, organism and patient information from case reports on the topic.

METHODS

A literature search was performed examining articles describing diseases caused by non-meningococcal and non-gonococcal Neisseria.

FINDINGS

Neisseria present as opportunistic pathogens causing a wide variety of diseases including serious presentations, endocarditis being the most common condition described and N. mucosa the most commonly presenting pathogen overall. Disease may occur in otherwise healthy patients, although risk factors for infection include recent surgery, an immunocompromised state, poor oral health, and intravenous drug use.

CONCLUSIONS

Commensal Neisseria infections are rare but can present serious invasive diseases. Further research is required to determine why some species cause disease more than others or why some are inclined towards particular manifestations.

Non-capsulated Neisseria meningitidis sepsis in a paroxysmal nocturnal hemoglobinuria patient treated with ravulizumab: case report and review of the literature

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare acquired haematopoietic stem cell disease characterized by complement-mediated intravascular hemolysis, thrombosis, and bone marrow failure. Eculizumab and ravulizumab are anti-C5 monoclonal antibodies that reduce hemolysis, anaemia and thrombotic risk, but are associated with increased risk of infection with encapsulated bacteria, including Neisseria meningitidis. We report a case of life-threatening infection by non-groupable Neisseria meningitidis in a young PNH patient treated with ravulizumab. Despite prompt admission to the intensive care unit, microbe isolation was delayed due to the negativity of capsular antigens, and the patient required intubation, dialysis, and transfusion support for pancytopenia. Notably, PNH disease activity remained controlled and no additional anti-C5 doses were administered. Increasing awareness regarding septic risk in PNH patients on complement inhibitors despite vaccinations is pivotal. A warning about serotypes generally not pathogenetic and not covered by vaccination, such as non-capsulated forms, is emerging.

Complement: Functions, location and implications

The complement system, an arm of the innate immune system plays a critical role in both health and disease. The complement system is highly complex with dual possibilities, helping or hurting the host, depending on the location and local microenvironment. The traditionally known functions of complement include surveillance, pathogen recognition, immune complex trafficking, processing and pathogen elimination. The noncanonical functions of the complement system include their roles in development, differentiation, local homeostasis and other cellular functions. Complement proteins are present in both, the plasma and on the membranes. Complement activation occurs both extra- and intracellularly, which leads to considerable pleiotropy in their activity. In order to design more desirable and effective therapies, it is important to understand the different functions of complement, and its location-based and tissue-specific responses. This manuscript will provide a brief overview into the complex nature of the complement cascade, outlining some of their complement-independent functions, their effects at different locale, and their implication in disease settings.

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.

Treatment preference and quality of life impact: ravulizumab vs eculizumab for atypical hemolytic uremic syndrome

Aim: Ravulizumab and eculizumab are complement C5 inhibitors approved for the treatment of atypical hemolytic uremic syndrome (aHUS). Ravulizumab requires less frequent infusions than eculizumab, which may reduce treatment burden. This study investigated patients' treatment preferences and the impact of both treatments on patient and caregiver quality of life. Materials & methods: Two surveys were conducted (one for adult patients with aHUS and one for caregivers of pediatric patients with aHUS) to quantitatively assess treatment preference and the patient- and caregiver-reported impact of ravulizumab and eculizumab on quality of life. Patients were required to have a diagnosis of aHUS, to be currently receiving treatment with ravulizumab and to have received prior treatment with eculizumab. Participants were recruited via various sources: the Alexion OneSource™ patient support program, the Rare Patient Voice recruitment agency, the aHUS Foundation and directly via a clinician involved in the study. Results: In total, 50 adult patients (mean age: 46.5 years) and 16 caregivers of pediatric patients (mean age: 10.1 years) completed the surveys. Most adult patients (94.0%) and all caregivers reported an overall preference for ravulizumab over eculizumab; infusion frequency was one of the main factors for patients when selecting their preferred treatment. Fewer patients reported disruption to daily life and the ability to go to work/school due to ravulizumab infusion frequency (4.0% and 5.7%, respectively) than eculizumab infusion frequency (72.0% and 60.0%), with similar results for caregivers. Conclusion: Adult patients and caregivers of pediatric patients indicated an overall preference for ravulizumab than eculizumab for the treatment of aHUS, driven primarily by infusion frequency. This study contributes to the emerging real-world evidence on the treatment impact and preference in patients with aHUS.

Vaccinations in hematological patients in the era of target therapies: Lesson learnt from SARS-CoV-2

Novel targeting agents for hematologic diseases often exert on- or off-target immunomodulatory effects, possibly impacting on response to anti-SARS-CoV-2 vaccinations and other vaccines. Agents that primarily affect B cells, particularly anti-CD20 monoclonal antibodies (MoAbs), Bruton tyrosine kinase inhibitors, and anti-CD19 chimeric antigen T-cells, have the strongest impact on seroconversion. JAK2, BCL-2 inhibitors and hypomethylating agents may hamper immunity but show a less prominent effect on humoral response to vaccines. Conversely, vaccine efficacy seems not impaired by anti-myeloma agents such as proteasome inhibitors and immunomodulatory agents, although lower seroconversion rates are observed with anti-CD38 and anti-BCMA MoAbs. Complement inhibitors for complement-mediated hematologic diseases and immunosuppressants used in aplastic anemia do not generally affect seroconversion rate, but the extent of the immune response is reduced under steroids or anti-thymocyte globulin. Vaccination is recommended prior to treatment or as far as possible from anti-CD20 MoAb (at least 6 months). No clearcut indications for interrupting continuous treatment emerged, and booster doses significantly improved seroconversion. Cellular immune response appeared preserved in several settings.

C5a-licensed phagocytes drive sterilizing immunity during systemic fungal infection

Systemic candidiasis is a common, high-mortality, nosocomial fungal infection. Unexpectedly, it has emerged as a complication of anti-complement C5-targeted monoclonal antibody treatment, indicating a critical niche for C5 in antifungal immunity. We identified transcription of complement system genes as the top biological pathway induced in candidemic patients and as predictive of candidemia. Mechanistically, C5a-C5aR1 promoted fungal clearance and host survival in a mouse model of systemic candidiasis by stimulating phagocyte effector function and ERK- and AKT-dependent survival in infected tissues. C5ar1 ablation rewired macrophage metabolism downstream of mTOR, promoting their apoptosis and enhancing mortality through kidney injury. Besides hepatocyte-derived C5, local C5 produced intrinsically by phagocytes provided a key substrate for antifungal protection. Lower serum C5a concentrations or a C5 polymorphism that decreases leukocyte C5 expression correlated independently with poor patient outcomes. Thus, local, phagocyte-derived C5 production licenses phagocyte antimicrobial function and confers innate protection during systemic fungal infection.

Crovalimab treatment in patients with paroxysmal nocturnal haemoglobinuria: Long-term results from the phase I/II COMPOSER trial

OBJECTIVES

This study reports long-term outcomes from the open-label extension (OLE) period of the Phase I/II COMPOSER trial (NCT03157635) that evaluated crovalimab in patients with paroxysmal nocturnal haemoglobinuria, who were treatment-naive or switched from eculizumab at enrolment.

METHODS

COMPOSER consists of four sequential parts followed by the OLE. The primary OLE objective was to assess long-term crovalimab safety, with a secondary objective to assess crovalimab pharmacokinetics and pharmacodynamics. Exploratory efficacy endpoints included change in lactate dehydrogenase (LDH), transfusion avoidance, haemoglobin stabilisation and breakthrough haemolysis (BTH).

RESULTS

A total 43 of 44 patients entered the OLE after completing the primary treatment period. Overall, 14 of 44 (32%) experienced treatment-related adverse events. Steady state exposure levels of crovalimab and terminal complement inhibition were maintained over the OLE. During the OLE, mean normalised LDH was generally maintained at ≤1.5× upper limit of normal, transfusion avoidance was achieved in 83%-92% of patients and haemoglobin stabilisation was reached in 79%-88% of patients across each 24-week interval. Five BTH events occurred with none leading to withdrawal.

CONCLUSIONS

Over a 3-year median treatment duration, crovalimab was well tolerated and sustained C5 inhibition was achieved. Intravascular haemolysis control, haemoglobin stabilisation and transfusion avoidance were maintained, signifying long-term crovalimab efficacy.

Therapeutic Potential of Targeting Complement C5a Receptors in Diabetic Kidney Disease

Diabetic kidney disease (DKD) affects 30-40% of patients with diabetes and is currently the leading cause of end-stage renal disease (ESRD). The activation of the complement cascade, a highly conserved element of the innate immune system, has been implicated in the pathogenesis of diabetes and its complications. The potent anaphylatoxin C5a is a critical effector of complement-mediated inflammation. Excessive activation of the C5a-signalling axis promotes a potent inflammatory environment and is associated with mitochondrial dysfunction, inflammasome activation, and the production of reactive oxygen species. Conventional renoprotective agents used in the treatment of diabetes do not target the complement system. Mounting preclinical evidence indicates that inhibition of the complement system may prove protective in DKD by reducing inflammation and fibrosis. Targeting the C5a-receptor signaling axis is of particular interest, as inhibition at this level attenuates inflammation while preserving the critical immunological defense functions of the complement system. In this review, the important role of the C5a/C5a-receptor axis in the pathogenesis of diabetes and kidney injuries will be discussed, and an overview of the status and mechanisms of action of current complement therapeutics in development will be provided.

A systematic literature review to examine the considerations around pregnancy in women of child-bearing age with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) or aquaporin 4 neuromyelitis optica spectrum disorder (AQP4+ NMOSD)

BACKGROUND

Aquaporin-4 antibody positive (AQP4+) neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are rare autoimmune diseases with overlapping phenotypes. Understanding their clinical manifestation prior to, during and after pregnancy may influence the management of women of child-bearing age (WOCBA) with these diseases.

METHODS

This systematic review identified relevant MEDLINE-indexed publications dated between 01 January 2011 and 01 November 2021, and congress materials from key conferences between 01 January 2019 and 01 November 2021. These were manually assessed for relevance to AQP4+ NMOSD and/or MOGAD in WOCBA, with selected data extracted and considered.

RESULTS

In total, 107 articles were retrieved and reviewed for relevancy, including 65 clinical studies. Limited evidence was found regarding a conclusive impact of either disease on female fertility, sexual function or menarche, and impact on maternal outcomes requires further investigation in both conditions to establish risk for pre-eclampsia, gestational diabetes and other complications relative to the general population. Collated data for pregnancy outcomes show clear risks in AQP4+ NMOSD to healthy delivery and a rise in annualised relapse rate postpartum that may require adaptation of treatment regimens. Disease activity appears to be attenuated during pregnancy in MOGAD patients with an increased risk of relapse during the postpartum months, but strong conclusions cannot be made due to a paucity of available data.

CONCLUSIONS

This review brings together the literature on AQP4+ NMOSD and MOGAD in WOCBA. The potential impact of pregnancy and the postpartum period on disease activity suggest a proactive management strategy early on may improve maternal and infant outcomes, but more clinical data are needed, particularly for MOGAD.

The anaphylatoxin C5a: Structure, function, signaling, physiology, disease, and therapeutics

The complement system is one of the oldest known tightly regulated host defense systems evolved for efficiently functioning cell-based immune systems and antibodies. Essentially, the complement system acts as a pivot between the innate and adaptive arms of the immune system. The complement system collectively represents a cocktail of ∼50 cell-bound/soluble glycoproteins directly involved in controlling infection and inflammation. Activation of the complement cascade generates complement fragments like C3a, C4a, and C5a as anaphylatoxins. C5a is the most potent proinflammatory anaphylatoxin, which is involved in inflammatory signaling in a myriad of tissues. This review provides a comprehensive overview of human C5a in the context of its structure and signaling under several pathophysiological conditions, including the current and future therapeutic applications targeting C5a.

How I diagnose and treat atypical hemolytic uremic syndrome

Our understanding and management of atypical hemolytic uremic syndrome (aHUS) have dramatically improved in the last decade. aHUS has been established as a prototypic disease resulting from a dysregulation of the complement alternative C3 convertase. Subsequently, prospective nonrandomized studies and retrospective series have shown the efficacy of C5 blockade in the treatment of this devastating disease. C5 blockade has become the cornerstone of the treatment of aHUS. This therapeutic breakthrough has been dulled by persistent difficulties in the positive diagnosis of aHUS, and the latter remains, to date, a diagnosis by exclusion. Furthermore, the precise spectrum of complement-mediated renal thrombotic microangiopathy is still a matter of debate. Nevertheless, long-term management of aHUS is increasingly individualized and lifelong C5 blockade is no longer a paradigm that applies to all patients with this disease. The potential benefit of complement blockade in other forms of HUS, notably secondary HUS, remains uncertain.

Complement Inhibition in Myasthenia Gravis and Neuromyelitis Optica Spectrum Disorder

The complement system is a tightly controlled signaling network that plays a role in innate immune surveillance. However, abnormal signaling through this pathway contributes to tissue damage in several inflammatory, autoimmune, and degenerative diseases. Myasthenia gravis (MG) and neuromyelitis optica spectrum disorders (NMOSD) have complement dysfunction at the core of pathogenesis, providing a strong rationale for therapeutic targeting of complement components. The purpose of this paper is to briefly review the role of complement activation in the pathogenesis of MG and NMOSD, to discuss the rationale and evidence for complement inhibition as a method to manage these diseases, and to provide a Canadian perspective on the use of complement inhibition therapy through real-world cases of MG and NMOSD.

Management of infection in PNH patients treated with eculizumab or other complement inhibitors: Unmet clinical needs

This article presents the results of group discussion among an ad hoc constituted panel of experts aimed at identifying and addressing unmet clinical needs (UCNs) in the management of infectious risk associated with eculizumab or new terminal complement inhibitors (CIs) in paroxysmal nocturnal hemoglobinuria (PNH). With the Delphi technique, the most clinically relevant UCNs in PNH patients candidate to or on terminal CI were selected. They resulted to be: optimizing the infection prevention measures; developing non pharmacological infectious risk-mitigation strategies; improving the management of disease exacerbation during infectious complications. For each of these issues consensus opinions were provided and, when appropriate, proposals for advancement in clinical practice were addressed. The hope is that this comprehensive overview will serve to improve the practice of CIs therapy and inform the design and implementation of new studies in the field.

The case for complement component 5 as a target in neurodegenerative disease

INTRODUCTION

Complement-based drug discovery is undergoing a renaissance, empowered by new advances in structural biology, complement biology and drug development. Certain components of the complement pathway, particularly C1q and C3, have been extensively studied in the context of neurodegenerative disease, and established as key therapeutic targets. C5 also has huge therapeutic potential in this arena, with its druggability clearly demonstrated by the success of C5-inhibitor eculizumab.

AREAS COVERED

We will discuss the evidence supporting C5 as a target in neurodegenerative disease, along with the current progress in developing different classes of C5 inhibitors and the gaps in knowledge that will help progress in the field.

EXPERT OPINION

Validation of C5 as a therapeutic target for neurodegenerative disease would represent a major step forward for complement therapeutics research and has the potential to furnish disease-modifying drugs for millions of patients suffering worldwide. Key hurdles that need to be overcome for this to be achieved are understanding how C5a and C5b should be targeted to bring therapeutic benefit and demonstrating the ability to target C5 without creating vulnerability to infection in patients. This requires greater biological elucidation of its precise role in disease pathogenesis, supported by better chemical/biological tools.

Proposal for individualized dosing of eculizumab in atypical haemolytic uraemic syndrome: patient friendly and cost-effective

BACKGROUND

Eculizumab is a lifesaving yet expensive drug for atypical haemolytic uraemic syndrome (aHUS). Current guidelines advise a fixed-dosing schedule, which can be suboptimal and inflexible in the individual patient.

METHODS

We evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) [classical pathway (CP) activity levels] of eculizumab in 48 patients, consisting of 849 time-concentration data and 569 CP activity levels. PK-PD modelling was performed with non-linear mixed-effects modelling. The final model was used to develop improved dosing strategies.

RESULTS

A PK model with parallel linear and non-linear elimination rates best described the data with the parameter estimates clearance 0.163 L/day, volume of distribution 6.42 L, maximal rate 29.6 mg/day and concentration for 50% of maximum rate 37.9 mg/L. The PK-PD relation between eculizumab concentration and CP activity was described using an inhibitory Emax model with the parameter estimates baseline 101%, maximal inhibitory effect 95.9%, concentration for 50% inhibition 22.0 mg/L and  Hill coefficient 5.42. A weight-based loading dose, followed by PK-guided dosing was found to improve treatment. On day 7, we predict 99.95% of the patients to reach the efficacy target (CP activity <10%), compared with 94.75% with standard dosing. Comparable efficacy was predicted during the maintenance phase, while the dosing interval could be prolonged in ∼33% of the population by means of individualized dosing. With a fixed-dose 4-week dosing interval to allow for holidays, treatment costs will increase by 7.1% and we predict 91% of the patients will reach the efficacy target.

CONCLUSIONS

A patient-friendly individualized dosing strategy of eculizumab has the potential to improve treatment response at reduced costs.

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.

Zilucoplan in immune-mediated necrotising myopathy: a phase 2, randomised, double-blind, placebo-controlled, multicentre trial

Background

Immune-mediated necrotizing myopathy (IMNM) is an autoimmune myopathy characterised by proximal muscle weakness, high creatine kinase (CK) values, and autoantibodies recognizing 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) or the signal recognition particle (SRP). There are currently no approved therapies for IMNM and many patients experience active disease despite off-label treatment with intravenous immunoglobulin, glucocorticoids, and immunosuppressants. Detection of complement-activating anti-HMGCR and anti-SRP autoantibodies and the presence of complement deposition on the sarcolemma of non-necrotic myofibers led to the hypothesis that complement activation may be pathogenic in IMNM, therefore zilucoplan, a complement component 5 (C5) inhibitor, could be a potential therapy.

Methods

IMNM01, a phase 2, multicenter, randomised, double-blind, placebo-controlled study (NCT04025632) at 15 sites (four countries) evaluated efficacy, safety, and tolerability of zilucoplan in adult participants with anti-HMGCR or anti-SRP autoantibody-positive IMNM. Participants were randomised 1:1 to receive daily subcutaneous zilucoplan (0·3mg/kg) or placebo for eight weeks; with optional enrolment in the study open-label extension. Primary efficacy endpoint was percent change from baseline to Week 8 in CK levels. Secondary endpoints included safety.

Findings

Between 07 November 2019 and 07 January 2021, 27 participants (13 female and 14 male) received zilucoplan (n=12) or placebo (n=15) and completed the 8-week main study. At Week 8 there were no clinically relevant or statistically significant differences, despite target engagement based on mode of action, between treatment arms in mean percent change (standard deviation) of CK levels versus baseline (-9·86% [26·06] versus -20·72% [31·22] in zilucoplan [n=10] and placebo arms [n=14], p=0·46, respectively) and no clinically relevant improvement over time within the treatment arm. There were no unexpected adverse safety or tolerability findings. Treatment emergent adverse events (TEAEs) and serious TEAEs were reported in n=9 (75·0%) vs n=13 (86·7%) and n=0 (0%) and n=3 (20·0%) participants, respectively. The most frequent TEAEs were headache (n=4 in both groups [33·3% and 26·7%, respectively]) and nausea (n=3 in both groups [25·0% and 20·0%, respectively]).

Interpretation

C5 inhibition does not appear to be an effective treatment modality for IMNM. Rather than driving myofiber necrosis, complement activation may be secondary to muscle injury.

Funding

Study funded by Ra Pharmaceuticals (now part of UCB Pharma).

Neuroimmunological Disorders

Multiple sclerosis is a disease that tends to affect women during their childbearing years. Although relapse risk decreases during pregnancy, patients should still be optimized on disease-modifying therapy before and after pregnancy to minimize gaps in treatment. Exclusive breastfeeding may reduce the chances of disease relapse postpartum, and many disease-modifying therapies are considered to be safe while breastfeeding. Treatments for other neuroimmunologic disorders such as neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein antibody-associated disease, neurosarcoidosis, and central nervous system vasculitis may require rituximab before and prednisone or intravenous immunoglobulin therapy during pregnancy.

Treatment considerations in myasthenia gravis for the pregnant patient

INTRODUCTION

Myasthenia gravis (MG) is an autoimmune disease where muscle antibodies form against the acetylcholine receptor (AChR), MuSK, or LRP4 at the neuromuscular junction leading to weakness. Patients worry about consequences for pregnancy, giving birth, nursing, and child outcome.

AREAS COVERED

This review lists the pharmacological treatments for MG in the reproductive age and gives recommendations. Consequences for pregnancy, giving birth, breastfeeding, and child outcome are discussed.

EXPERT OPINION

Pyridostigmine, corticosteroids in low doses, and azathioprine are regarded as safe during pregnancy and should be continued. Mycophenolate mofetil, methotrexate, and cyclophosphamide should not be used in reproductive age. Rituximab should not be given during pregnancy. Other monoclonal IgG antibodies such as eculizumab and efgartigimod should be given only when regarded strictly necessary to avoid long-term and severe incapacity. Intravenous and subcutaneous immunoglobulin and plasma exchange are safe treatments during pregnancy and are recommended for exacerbations with moderate or severe generalized weakness. Most MG women have spontaneous vaginal deliveries. Indications for Cesarean section are obstetrical and similar to non-MG women. Neonatal myasthenia manifests as a transient weakness caused by the mother's IgG muscle antibodies and affects 10% of the babies. MG women should be supported in their wish to have children.