Complement Inhibitor Research Articles

#2262 Renal outcomes of postpartum atypical hemolytic uremic syndrome treated with plasma exchange

Abstract Background and Aims Postpartum acute kidney injury (AKI) with features of thrombotic microangiopathy (TMA) are particularly challenging and complex cases. Causes include Preeclampsia (PE), hemolysis, elevated liver enzymes and low platelet count syndrome (HELLP) and atypical hemolytic uremic syndrome (aHUS). In a limited resource setting, it is difficult to diagnose such cases with more than standard blood tests. Therapeutic Plasma exchange (TPE) is the only available option for treatment in the absence of complement inhibitors. This study evaluates renal outcomes in patients with aHUS treated with plasma exchange. Method This is a single centre observational study conducted in a Tertiary Obstetric Intensive Care unit. The data of women who were admitted with postpartum AKI from January 2021 to October 2023 was retrospectively collected and analyzed. We used the following criteria to diagnose postpartum atypical HUS (Serum creatinine ≥1.9 mg/dL, Lactate dehydrogenase (LDH) ≥1832 U/L, or serum creatinine ≥1.9 mg/dL in combination with LDH ≥600 U/L) [1]. Inclusion criteria include women older than 18 yrs with microangiopathic hemolytic anaemia, schistocytes on peripheral blood film, negative direct antiglobulin test (DAT) and platelet count <100 /mm3.Lack of improvement of kidney functions and hemolysis 72 hours after delivery. Patients with sepsis, disseminated intravascular coagulopathy (DIC), postpartum hemorrhage (PPH) and chronic kidney disease were excluded. We identified 10 patients with postpartum aHUS. Peak creatinine, LDH, AST and Nadir platelet count and hemoglobin were recorded. Patients were followed up in the nephrology outpatient clinic. Results Fifty-two patients developed postpartum AKI in the study period. Ten patients (19%) were diagnosed with aHUS according to the above-mentioned criteria. Mean age was 24.5 ± 6.9 yrs. Median peak creatinine 5.1 (2.6-7) mg/dl, LDH 1950 (612-4000) U/L, AST 246 (150-699) U/L. Median nadir hemoglobin 7.25 (6-8.2) g/dl and platelets 57 (41-95)/mm3. All 10 patients received 3 to 6 sessions of TPE guided by platelets and LDH levels. All patients required at least 3 sessions of hemodialysis. Eight patients received TPE with plasma filter and 2 had centrifugal TPE (due to lack of plasma filters). Two patients died during ICU admission. Two months after discharge 4 (50%) patients had partial recovery of kidney functions average creatinine (3.5 ± 0.8) mg/dl and four (50%) remained dialysis dependent. Six of these patients had kidney biopsies, three biopsies showed a picture of thrombotic microangiopathy and two showed thrombotic microangiopathy with renal cortical necrosis. The other patient was lost to follow up. Conclusion It is difficult to diagnose and treat aHUS in a resource limited setting. The available treatment with therapeutic plasma exchange has poor renal outcomes.

#2066 Treatment patterns of patients with complement 3 glomerulopathy (C3G): a retrospective linked electronic medical record (EMR) and claims analysis

Abstract Background and Aims C3G is characterised by C3 deposition in the glomeruli, caused by dysregulation of the alternative complement pathway. Currently, there are no approved therapies for C3G. The aim of this analysis was to evaluate treatment patterns in patients with C3G in the United States (US). Methods This was a retrospective cohort study of patients with C3G, with an EMR and linked pharmacy and medical claims data in the US HealthVerity database, who were diagnosed between Jan 1, 2017 and Sep 30, 2021 and aged ≥12 years at diagnosis. Included patients had database records for ≥12 months before (baseline period) and after (follow-up period) the index date (date of first C3G diagnosis, identified by International Classification of Diseases 10th Revision Clinical Modification [ICD-10-CM] and Systematized Nomenclature of Medicine [SNOMED] diagnosis codes). Endpoints included: proportion of patients receiving a treatment, including supportive care (angiotensin-converting enzyme inhibitors [ACEi]/angiotensin II receptor blockers [ARB]), immunosuppressants (IM; including corticosteroids [CS]/glucocorticoids [GC] and mycophenolate mofetil [MMF]), and eculizumab; proportion of patients discontinuing treatment; and duration of treatment. Discontinuing treatment was defined as the absence of a subsequent claim for medication for ≥60 days. Results were assessed using descriptive statistics and analysed by Fisher's exact test, Mann–Whitney U test, or Student's t-test, as appropriate. Results The final cohort included 683 patients. Overall, 346 (50.7%) patients had ≥1 treatment record for C3G during follow-up (median follow-up 24.0 months; median time from index to first treatment 1.1 months). Mean age (standard deviation) of treated and untreated patients was 47.7 (19.4) and 39.6 (18.0) years (P < 0.0001), respectively; 54.3% of treated patients and 72.7% of untreated patients were female (P < 0.0001). Comorbidities reported in treated and untreated patients, respectively, included: hypertension (75.1% and 33.5%; P < 0.0001) and type II diabetes (34.7% and 12.8%; P < 0.0001). Baseline proteinuria data were available for 39 (11.3%) treated patients and 11 (3.3%) untreated patients (P < 0.0001). Median (lower quartile, upper quartile) proteinuria levels were 1.9 (0.7, 3.3) g/g and 0.2 (0.1, 2.3) g/g for the treated and untreated populations, respectively (P = 0.05). Among treated patients (n = 346), most (76.0%) received an ACEi/ARB alone in the first line, 14.2% received IM alone, and 5.8% received concomitant ACEi/ARB and IM (Table 1). A small number of remaining patients received a sodium-glucose cotransporter-2 inhibitor (SGLT2i) ± ACEi/ARB (2.9%), or eculizumab ± IM (1.2%). Less than half of treated patients (43.9%) received second-line therapy, and 17.6%, 6.6%, and 2.0%, respectively, received subsequent lines of treatment. Among treated patients, the most common treatment sequence was ACEi/ARB alone in the first line, without subsequent lines of therapy (42.2%); 30.9% of treated patients received IM (alone or in combination with other treatments) at any time during follow-up. Median duration of treatment in months (95% confidence interval) in any line was 14.9 (9.9, 18.4) for ARB, 8.6 (7.5, 11.1) for ACEi, 7.4 (3.3, 22.6) for SGLT2i, 4.7 (3.0, 6.6) for MMF, and 1.0 (0.9, 3.0) for CS/GC. During follow-up, 225 (65.0%) patients discontinued treatment: 22 (9.8%) and 203 (90.2%) patients restarted and did not restart therapy, respectively. Conclusions These real-world data show that only half of patients with C3G had a record of treatment during follow-up. Compared with the untreated population, patients who received treatment were older, more likely to be male, and more likely to have hypertension or type II diabetes. Among treated patients, the most common treatment sequence was supportive care with an ACEi/ARB alone, and less than one-third received IM at any time during follow-up. Use of the complement inhibitor, eculizumab, was low in this population. A large proportion of patients discontinued treatment during follow-up; given the progressive nature of C3G, these data may highlight the need for novel therapies in the treatment of C3G.

#1276 Clinical practice of complement inhibitor use in hemolytic uremic syndrome: findings from the European rare kidney disease registry

Abstract Background and Aims Over the last decade, significant advancements have emerged in the field of rare kidney diseases, notably the introduction of C5 inhibitor therapy. The C5 inhibition has transformed the prognosis for atypical Hemolytic Uremic Syndrome (aHUS), offering improved clinical outcomes. However, despite these advancements, the utilization of C5 inhibitor therapy varies significantly, with disparities in treatment duration, reasons for discontinuation, and consideration of extending treatment to patients with infectious HUS (iHUS). This variability is further compounded by the considerable cost associated with C5 inhibitor treatment. Method This retrospective cohort study utilized data from the ERKNet Registry. The study cohort comprised 608 HUS patients enrolled in the ERKNet Registry between November 2018 and September 2023. The dataset encompassed patient demographics, disease and diagnostic records, medication profiles, dialysis or transplantation requirements, kidney function monitoring at the last visit, and clinical outcomes. Results Among 230 aHUS patients, 23 underwent kidney transplantation. 11 received C5 inhibitor therapy before kidney failure. The majority of these patients had genetic aHUS with various mutations (3 CFH, 2 CFI, and 1 CD46). The only death in the study was from this group of patients, unresponsive to C5 Inhibition. Out of 175 aHUS patients treated with Eculizumab, 23 (13%) transitioned to Ravulizumab. Among 104 patients who discontinued C5 inhibitors, 14 (14%) had to resume treatment, half of them with genetic aHUS, with 3 cases of CD46 mutations, 2 cases CFHR5 mutations, and one each involving mutations in CFI and C3. Only two patients required dialysis.. Among 371 iHUS patients, 82 (22%) received C5 Inhibitor treatment. Conclusion In the context of aHUS, we found that discontinuing C5 inhibitors is generally safe, with a slightly higher relapse rate in patients with complement gene variants, though most relapses were mild, requiring dialysis in only a few cases. Long-term follow-up revealed a return to normal kidney function following TMA relapses. Transitioning from Eculizumab to Ravulizumab exhibited promising outcomes, with no relapses or kidney failures in 23 patients. Our analysis of C5 inhibitor use in iHUS emphasized its association with more severe disease progression. While some studies question C5 inhibitors' acute-phase efficacy, others report remarkable improvements in patients unresponsive to other treatments. Overall, our findings underscore the safety of discontinuation practices, the potential benefits of Ravulizumab, and the ongoing need for further research on C5 inhibitor treatment in iHUS.

#243 Characteristics and safety in patients with atypical haemolytic uraemic syndrome switching to ravulizumab from eculizumab: a global registry analysis

Abstract Background and Aims Atypical haemolytic uraemic syndrome (aHUS) is a progressive rare disease caused by complement dysregulation that can result in severe organ damage and death. Ravulizumab, a next-generation terminal complement inhibitor, was designed via targeted modification of eculizumab to enhance antibody recycling and attenuate target-mediated drug disposition to achieve an extended half-life. Ravulizumab was first approved for the treatment of aHUS in 2019. Real-world evidence with ravulizumab in patients with aHUS is limited. This analysis aimed to assess real-world safety outcomes in patients with aHUS who switched to ravulizumab from eculizumab using data from the Global aHUS Registry. Method The Global aHUS Registry is a multicentre study (NCT01522183) collecting retrospective and prospective data on patients with aHUS since 2012, making it the largest registry of real-world data for this patient population. Safety outcomes (including serious and non-serious adverse events [AEs], meningococcal infections and deaths) were assessed in patients with aHUS who switched to ravulizumab from eculizumab up to 3 July 2023. Results Overall, 60 patients were included in the analysis population and evaluated for baseline demographics and characteristics, and safety outcomes. Most patients were female (70%) and the median (range) age at ravulizumab initiation was 34 (2–72) years (Table 1). In total, 27 patients (45%) had pathogenic complement variants and 19 (32%) had a kidney transplantation prior to ravulizumab initiation. Among extrarenal manifestations (experienced at any time during observation), the most common were gastrointestinal (n = 29 [48%]), central nervous system (n = 19 [32%]) and cardiovascular (n = 15 [25%]). The median (range) time on treatment was 21 (2–40) months for ravulizumab and 62 (11–155) months for eculizumab. No new events of thrombotic microangiopathy, dialysis or kidney transplantation were reported during ravulizumab treatment. One patient who was on chronic dialysis under eculizumab switched to ravulizumab; the patient returned to eculizumab (per local guidelines) for a planned kidney transplantation with the intention to switch back to ravulizumab post-transplantation (data not yet available). In total, 20 AEs were reported in 13 patients, of which none were unexpected (Table 2). Three serious AEs were reported in three patients (1 event each of squamous cell carcinoma, atrial fibrillation, SARS-CoV-2 infection). Ten AEs occurred in eight patients who received a kidney transplantation before ravulizumab initiation. Treatment-related AEs occurred in two patients while on ravulizumab: one infusion reaction event in one patient was assessed to be probably related to ravulizumab by the investigator (the event resolved within 24 hours and the patient continued treatment); one patient experienced headaches and fatigue while on ravulizumab, which resolved after switching back to eculizumab. The most common AEs were infection (n = 7 events), including SARS-CoV-2 infection (n = 4), influenza (n = 1), infection without focus (n = 1) and pulmonary nodular infiltration (n = 1); all infections were resolved except for one event of SARS-CoV-2 infection that was ongoing/persistent. No meningococcal infections or deaths were reported during ravulizumab treatment. Conclusion This analysis from the Global aHUS Registry reports the largest real-world safety dataset from patients with aHUS treated with ravulizumab. No unexpected AEs, meningococcal infections or deaths were reported during ravulizumab treatment. These data provide evidence for the long-term safety of ravulizumab in patients with aHUS who switched from eculizumab and reinforce the positive benefit–risk profile of ravulizumab.

#2663 Assessment of in situ alternative and classical convertases as indicators of ongoing glomerular complement activation in IgA nephropathy

Abstract Background and Aims Complement activation is involved in IgA nephropathy (IgAN), opening up new avenues for complement-targeting therapies. However, precise patient selection and optimal timing for these therapies are essential. Current diagnostic methods of complement activation in IgAN, based on immunostaining, lack precision in identifying specific pathway(s) involved and distinguishing ongoing from past complement activation. Method Complement deposition analysis was conducted on kidney biopsy samples from 53 patients with primary IgAN at diagnosis (NCT05234463). Glomerular complement deposition was assessed through immunohistochemistry for C4d and C5b-9 and immunofluorescence for C3b/iC3b and C1q. In situ detection of C3/C5 convertases complexes from complement classical/lectin (C4b2b) and alternative pathways (C3bBb) was performed on paraffin-embedded kidney biopsies from 33 patients using a proximity ligation assay (Duolink®, Sigma). Kidney biopsies from patients with lupus nephritis (LN) and C3 glomerulopathy (C3G) were used as positive controls for classical/lectin and alternative convertases staining, respectively. The signals corresponding to the convertases were quantified using QuPath® Software and correlated with clinical parameters, MEST-C score and C5b-9 staining. Results At diagnosis, all 53 IgAN patients (100%) exhibited C3 mesangial deposition. Additionally, 51.2% were positive for C4d, 16.5% had C1q deposition and 62.7% had C5b-9 deposition. In situ analysis of C3/C5 convertases revealed the presence of glomerular C3bBb convertases in 20/33 (60.6%) patients, with a median positive area of 14.9 [2.5-26.5]%o of glomerular surface. C4b2b convertases were detected in 21/33 patients (63.6%), with a median glomerular positive area of 8.1 [3.4-12.1]%o. Both C3bBb and C4b2b convertases were detected in 13/33 (39.4%) patients (Fig. 1). By contrast, no convertases were detected in 5/33 (15.2%) patients despite positive C3b/iC3b deposition. The intensity of C3bBb staining positively correlated with terminal pathway C5b-9 glomerular deposits (p = 0.0011, r2 0.29). Patients with MEST-C score S1 lesions and/or interstitial fibrosis/tubular atrophy (T1-2) exhibited a more pronounced intensity of C3bBb at diagnosis (p = 0.0093). Conclusion Our study, for the first time, presents evidence of ongoing complement activation at the tissue level in IgA nephropathy (IgAN), showing variable intensities among patients. The visualization of in situ C3/C5 convertases could enhance the functional aspect of pathological examination, helping identify patients with ongoing complement activation, making them potential candidates for complement inhibitors. Further research is necessary to investigate the kinetics of this staining over the natural course of IgAN and its implications for IgAN progression.

Targeted complement inhibition using bispecific antibodies that bind local antigens and endogenous complement regulators.

Complement activation protects against infection but also contributes to pathological mechanisms in a range of clinical conditions such as autoimmune diseases and transplant rejection. Complement-inhibitory drugs, either approved or in development, usually act systemically, thereby increasing the risk for infections. We therefore envisioned a novel class of bispecific antibodies (bsAbs) which are capable of site-directed complement inhibition by bringing endogenous complement regulators in the vicinity of defined cell surface antigens. Here, we analyzed a comprehensive set of obligate bsAbs designed to crosslink a specific target with either complement regulator factor H (FH) or C4b-binding protein (C4BP). The bsAbs were assessed for their capacity to inhibit complement activation and cell lysis in an antigen-targeted manner. We observed that the bsAbs inhibited classical, lectin, and alternative pathway complement activation in which sufficient endogenous serum FH and C4BP could be recruited to achieve local inhibition. Importantly, the bsAbs effectively protected antigen-positive liposomes, erythrocytes, and human leukocytes from complement-mediated lysis. In conclusion, localized complement inhibition by bsAbs capable of recruiting endogenous human complement regulators (such as FH or C4BP) to cell surfaces potentially provides a novel therapeutic approach for the targeted treatment of complement-mediated diseases.

Crovalimab: First Approval.

Crovalimab (®; PiaSky) is a humanized, anti-complement component C5 (anti-C5) recycling monoclonal antibody developed by Chugai Pharmaceutical, in collaboration with Roche, which is being investigated for the treatment of complement-mediated diseases, including paroxysmal nocturnal haemoglobinuria (PNH), atypical haemolytic uremic syndrome, lupus nephritis and sickle cell disease. Crovalimab targets C5, inhibiting its cleavage to C5a and C5b, thus blocking the terminal complement pathway and preventing intravascular haemolysis in PNH. Crovalimab is designed to bind to the antigen repeatedly, resulting in sustained complement inhibition at a lower dosage, and allowing for once-monthly subcutaneous administration. In February 2024, subcutaneous crovalimab received its first approval in China for the treatment of adolescents and adults (aged ≥ 12 years) with PNH who have not been previously treated with complement inhibitors. Crovalimab has since been approved in Japan in March for use in the treatment of PNH, including in treatment-naïve and previously treated patients. Crovalimab is also under regulatory review for the treatment of naïve and previously treated patients with PNH in multiple countries, including the USA and the European Union. This article summarizes the milestones in the development of crovalimab leading to this first approval in China for the treatment of PNH.

Sequential administration of anti-complement component C5 eculizumab and type-2 anti-CD20 obinutuzumab for the treatment of early antibody-mediated rejection after kidney transplantation: A proof of concept

Kidney transplant (KT) candidates with donor-specific antibodies (DSA) exhibit exceedingly high antibody-mediated rejection (ABMR) and allograft loss rates. Currently, treatment of ABMR remains an unmet clinical need. We report the use of the anti-C5 eculizumab and the type-2 anti-CD20 obinutuzumab in two patients with early ABMR. Eculizumab (900 mg IV) led to complete inhibition of the terminal complement cascade (unremarkable AP50 and CH50 activity) and prompt stoppage of complement-dependent antibody-mediated allograft injury (clearance of intra-graft C4d and C5b-9 deposition). Despite complement inhibition, obinutuzumab (1000 mg IV) determined full and long-lasting peripheral B-cell depletion, with significant reduction in all DSA. Graft function improved, remaining stable up to three years of follow-up. No signs of active ABMR and rebound DSA were detected. Obinutuzumab B-cell depletion and inhibition of DSA production were not affected by complement blockage. Further studies are needed to confirm the potential benefit of obinutuzumab in association with complement inhibitors.

Drugs in Development to Treat IgA Nephropathy.

IgA nephropathy is a common glomerulonephritis consequent to the autoimmune response to aberrant glycosylated immunoglobulin (Ig) A antibodies. Although it has historically been considered a benign disease, it has since become clear that a substantial percentage of patients reach end-stage kidney failure over the years. Several therapeutic attempts have been proposed, with systemic steroids being the most prevalent, albeit burdened by possible serious adverse events. Thanks to the more in-depth knowledge of the pathogenesis of IgA nephropathy, new treatment targets have been identified and new drugs developed. In this narrative review, we summarise the molecules under clinical development for the treatment of IgA nephropathy. As a search strategy, we used PubMed, Google, ClinicalTrials.gov and abstracts from recent international congresses. TRF budesonide and sparsentan are the two molecules at a more advanced stage, just entering the market. Other promising agents are undergoing phase III clinical development. These include anti-APRIL and anti-BLyS/BAFF antibodies and some complement inhibitors. Other new possible strategies include spleen tyrosine kinase inhibitors, anti-CD40 ligands and anti-CD38 antibodies. In an era increasingly characterised by 'personalised medicine' and 'precision therapy' approaches and considering that the potential therapeutic armamentarium for IgA nephropathy will be very broad in the near future, the identification of biomarkers capable of helping the nephrologist to select the right drug for the right patient should be the focus of future studies.

Muscle-Specific Receptor Tyrosine Kinase Antibody Positive Myasthenia Gravis

Reportedly, patients with muscle-specific kinase (MuSK) antibody-positive myasthenia gravis (MG) account for approximately 3.0% of all patients with MG in Japan. Compared with patients who have acetylcholine receptor antibody-positive MG, those with MuSK antibody-positive MG show young-onset disease with female predominance, a low rate of ocular involvement (5.9%), and greater severity of dysphagia. The aforementioned types of MG are indistinguishable based on clinical symptoms and electrophysiological tests, and measurement of MuSK antibodies is essential for diagnosis. Thymectomy and complement inhibitors are not indicated for treatment, and acetylcholinesterase inhibitors, steroids, immunosuppressants, plasma exchange, intravenous immunoglobulin therapy, and neonatal Fc receptor inhibitors are used.

Illustrated State-of-the-Art Capsules of the ISTH 2024 Congress

Here, we present a series of illustrated capsules from the State of the Art (SOA) speakers at the 2024 International Society on Thrombosis and Haemostasis Congress in Bangkok, Thailand. This year’s Congress marks the first time that the International Society on Thrombosis and Haemostasis has held its flagship scientific meeting in Southeast Asia and is the first to be organized by an international Planning Committee. The Bangkok program will feature innovative science and clinical updates from around the world, reflecting the diversity and multidisciplinary growth of our field. In these illustrated SOA capsules, you will find an exploration of novel models of thrombosis and bleeding and biomaterial discoveries that can trigger or block coagulation. Thromboinflammation is now understood to drive many disease states, and the SOA speakers cover cellular and coagulation responses to COVID-19 and other infections. The theme of crosstalk between coagulation and inflammation expands with capsules on protein S signaling, complement, and fibrinolytic inhibitors. Novel agents for hemophilia and thrombosis prevention are introduced. Challenging clinical conditions are also covered, such as inherited platelet disorders and antiphospholipid antibody syndrome. The scientific program in Bangkok will also showcase the work of clinicians and scientists from all parts of the world and chronicle real-world challenges. For example, 2 SOA capsules address the diagnosis and management of von Willebrand disease in low-income settings. Take some time to browse through these short illustrated reviews; we’re sure that you’ll be entertained, educated, and inspired to further explore the world of thrombosis and hemostasis.

Complement regulation in the eye: implications for age-related macular degeneration.

Careful regulation of the complement system is critical for enabling complement proteins to titrate immune defense while also preventing collateral tissue damage from poorly controlled inflammation. In the eye, this balance between complement activity and inhibition is crucial, as a low level of basal complement activity is necessary to support ocular immune privilege, a prerequisite for maintaining vision. Dysregulated complement activation contributes to parainflammation, a low level of inflammation triggered by cellular damage that functions to reestablish homeostasis, or outright inflammation that disrupts the visual axis. Complement dysregulation has been implicated in many ocular diseases, including glaucoma, diabetic retinopathy, and age-related macular degeneration (AMD). In the last two decades, complement activity has been the focus of intense investigation in AMD pathogenesis, leading to the development of novel therapeutics for the treatment of atrophic AMD. This Review outlines recent advances and challenges, highlighting therapeutic approaches that have advanced to clinical trials, as well as providing a general overview of the complement system in the posterior segment of the eye and selected ocular diseases.

Evaluating the performance of optilite® C1Q and C2 turbidimetric assays in patients with complement deficiency or undergoing complement inhibitor therapy

Evaluating the performance of optilite® C1Q and C2 turbidimetric assays in patients with complement deficiency or undergoing complement inhibitor therapy

Complement inhibition treatment for geographic atrophy (GA): functional and morphological efficacy and relevant biomarkers in clinical practice

The approval of complement inhibitory therapeutic agents for the treatment of geographic atrophy (GA) has highlighted the need for reliable and reproducible measurement of disease progression and therapeutic efficacy. Due to its availability and imaging characteristics optical coherence tomography (OCT) is the method of choice. Using OCT analysis based on artificial intelligence (AI), the therapeutic efficacy of pegcetacoplan was demonstrated at the levels of both the retinal pigment epithelium (RPE) and photoreceptors (PR). Cloud-based solutions that enable monitoring of GA are already available.

Advances in Understanding and Managing Myasthenia Gravis: Current Trends and Future Directions.

Myasthenia gravis (MG) is an autoimmune illness characterized by autoantibodies against the acetylcholine receptor (AChR), muscle-specific tyrosine kinase (MuSK), and an increasing number of extra postsynaptic proteins. Pathogenic autoantibodies reduce the number of functional AChRs in the neuromuscular junction's (NMJ)muscle end plate. The cause of the autoimmune response is unknown, but thymic abnormalities and immune regulatory deficiencies are significant. The disease's incidence is likely influenced by genetic predisposition, with sex hormones and exercise playing a role. MGcan affect any age, race, or gender and can be caused by any stressor, with infections being the most frequent cause. Treatment focuses on airway support and the triggering incident. MG is a rare autoimmune disease causing fatigue-inducing weakness in the axial, respiratory, leg, and bulbar muscles. Initially affecting the eyes, most MGpatients experience at least one worsening symptom during their illness. The disease is mainly caused by antibodies against the AChR, dependence on the immune system within cells, and engagement of the complement system. The complement system plays a significant role in MG, and complement inhibition can both prevent the onset and slow its development. Ocular MG affects around 15% of people, with most patients having blocking antibodies against the cholinergic receptor. There may be correlations between thymoma and other autoimmune conditions, especially thyroid illness. Treatment and management for MGinvolve removing autoantibodies from circulation or blocking effector mechanisms using techniques such as complement inhibition, plasmapheresis, and B-cell elimination.

Beneficial versus Detrimental Effects of Complement-Microglial Interactions in Alzheimer's Disease.

Research indicates that brain-region-specific synapse loss and dysfunction are early hallmarks and stronger neurobiological correlates of cognitive decline in Alzheimer's disease (AD) than amyloid plaque and neurofibrillary tangle counts or neuronal loss. Even though the precise mechanisms underlying increased synaptic pruning in AD are still unknown, it has been confirmed that dysregulation of the balance between complement activation and inhibition is a crucial driver of its pathology. The complement includes three distinct activation mechanisms, with the activation products C3a and C5a, potent inflammatory effectors, and a membrane attack complex (MAC) leading to cell lysis. Besides pro-inflammatory cytokines, the dysregulated complement proteins released by activated microglia bind to amyloid β at the synaptic regions and cause the microglia to engulf the synapses. Additionally, research indicating that microglia-removed synapses are not always degenerating and that suppression of synaptic engulfment can repair cognitive deficits points to an essential opportunity for intervention that can prevent the loss of intact synapses. In this study, we focus on the latest research on the role and mechanisms of complement-mediated microglial synaptic pruning at different stages of AD to find the right targets that could interfere with complement dysregulation and be relevant for therapeutic intervention at the early stages of the disease.

Eculizumab in Adolescent Patients With Refractory Generalized Myasthenia Gravis: A Phase 3, Open-Label, Multicenter Study

BackgroundThis study evaluated the efficacy and safety of eculizumab, a terminal complement C5 inhibitor, in juvenile generalized myasthenia gravis (gMG). MethodsAdolescents aged 12 to 17 years with refractory anti-acetylcholine receptor (AChR) antibody-positive gMG received eculizumab (weekly induction [one to two doses of 600 mg or four doses of 900 mg] followed by maintenance doses [300 to 1200 mg] every two weeks for up to 26 weeks) in a phase 3, open-label multicenter study (NCT03759366). Change from baseline to week 26 in Quantitative Myasthenia Gravis (QMG) total score (primary end point) and secondary end points including Myasthenia Gravis-Activities of Daily Living (MG-ADL) total score, Myasthenia Gravis Composite score, Myasthenia Gravis Foundation of America postintervention status, EuroQol 5-Dimensions (Youth) and Neurological Quality-of-Life Pediatric Fatigue questionnaire scores, as well as pharmacokinetics, pharmacodynamics, and safety, were recorded. ResultsEleven adolescents (mean ± S.D. age 14.8 ± 1.8 years) were enrolled; 10 completed the primary evaluation period. Least-squares mean changes from baseline at week 26 were −5.8 (standard error [SE] 1.2; P = 0.0004) for QMG total score and −2.3 (SE 0.6; P = 0.0017) for MG-ADL total score. Overall, the primary and all secondary efficacy end point analyses met statistical significance from the first assessment and were sustained throughout. Complete terminal complement inhibition was sustained through 26 weeks in all patients. Treatment-emergent adverse events were all mild/moderate and predominantly unrelated to eculizumab. ConclusionsEculizumab was effective in reducing disease burden and was well tolerated in adolescents with refractory AChR antibody-positive gMG.

Ravulizumab facilitates reduced burden of vascular access, a major benefit in paediatric atypical haemolytic uraemic syndrome.

Atypical haemolytic uraemic syndrome (aHUS) is a rare thrombotic microangiopathy resulting from dysregulation of the alternative complement pathway, leading to multi-organ dysfunction and chronic kidney disease. Eculizumab is an anti-C5 monoclonal antibody therapy that has significantly improved aHUS disease control and patient outcomes, however it requires fortnightly intravenous dosing. This often necessitates long term central access and a high hospital attendance burden. Ravulizumab is a novel, next-generation anti-C5 monoclonal antibody engineered from eculizumab to reduce endosomal degradation of the antibody, increasing the dosing interval up to 8 weeks. In this retrospective case series we present the transition of three children with aHUS from eculizumab to ravulizumab from a single tertiary paediatric nephrology service. All patients underwent genomic and immunological work up for aHUS, with no cause found. After stabilisation with eculizumab, two patients developed macrovascular thrombotic complications associated with indwelling central vascular catheters, ultimately leading to central access failure. All patients were transitioned from eculizumab to ravulizumab without relapse of aHUS. One patient successfully underwent deceased donor kidney transplantation with ravulizumab for complement inhibition. All patients have transitioned to peripheral access for infusions given the reduced frequency of dosing, maintaining good control of aHUS for 2-4 years. Ravulizumab permits sufficiently reduced frequency of infusion to allow for administration by peripheral cannulation - removing the risks of long term central vascular access often required to deliver eculizumab to paediatric patients.

Molecular mechanism of complement inhibition by the trypanosome receptor ISG65

African trypanosomes replicate within infected mammals where they are exposed to the complement system. This system centres around complement C3, which is present in a soluble form in serum but becomes covalently deposited onto the surfaces of pathogens after proteolytic cleavage to C3b. Membrane-associated C3b triggers different complement-mediated effectors which promote pathogen clearance. To counter complement-mediated clearance, African trypanosomes have a cell surface receptor, ISG65, which binds to C3b and which decreases the rate of trypanosome clearance in an infection model. However, the mechanism by which ISG65 reduces C3b function has not been determined. We reveal through cryogenic electron microscopy that ISG65 has two distinct binding sites for C3b, only one of which is available in C3 and C3d. We show that ISG65 does not block the formation of C3b or the function of the C3 convertase which catalyses the surface deposition of C3b. However, we show that ISG65 forms a specific conjugate with C3b, perhaps acting as a decoy. ISG65 also occludes the binding sites for complement receptors 2 and 3, which may disrupt recruitment of immune cells, including B cells, phagocytes, and granulocytes. This suggests that ISG65 protects trypanosomes by combining multiple approaches to dampen the complement cascade.

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

BackgroundParoxysmal 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. ObjectivesTo evaluate the rates of thrombosis and meningococcal infections in patients with PNH treated with the complement component 3–targeted therapy pegcetacoplan. MethodsCumulative 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. ResultsAs 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. ConclusionEvent 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.