Triple-fusion protein (TriFu): A potent, targeted, enzyme-like inhibitor of all three complement activation pathways.

The introduction of a therapeutic anti-C5 antibody into clinical practice in 2007 inspired a surge into the development of complement-targeted therapies. This has led to the recent approval of a C3 inhibitory peptide, an antibody directed against C1s and a full pipeline of several complement inhibitors in preclinical and clinical development. However, no inhibitor is available that efficiently inhibits all three complement initiation pathways and targets host cell surface markers as well as complement opsonins. To overcome this, we engineered a novel fusion protein combining selected domains of the three natural complement regulatory proteins decay accelerating factor, factor H and complement receptor 1. Such a triple fusion complement inhibitor (TriFu) was recombinantly expressed and purified alongside multiple variants and its building blocks. We analyzed these proteins for ligand binding affinity and decay acceleration activity by surface plasmon resonance. Additionally, we tested complement inhibition in several in vitro/ex vivo assays using standard classical and alternative pathway restricted hemolysis assays next to hemolysis assays with paroxysmal nocturnal hemoglobinuria erythrocytes. A novel in vitro model of the alternative pathway disease C3 glomerulopathy was established to evaluate the potential of the inhibitors to stop C3 deposition on endothelial cells. Next to the novel engineered triple fusion variants which inactivate complement convertases in an enzyme-like fashion, stoichiometric complement inhibitors targeting C3, C5, factor B, and factor D were tested as comparators. The triple fusion approach yielded a potent complement inhibitor that efficiently inhibits all three complement initiation pathways while targeting to surface markers.

The complement model disease paroxysmal nocturnal hemoglobinuria.

We describe initial, current, and future aspects of complement activation and inhibition in the rare hematological disease paroxysmal nocturnal hemoglobinuria (PNH). PNH is a rare but severe hematological disorder characterized by complement-mediated intravascular hemolysis resulting in anemia and severe thrombosis. Insights into the complement-mediated pathophysiology ultimately led to regulatory approval of the first-in-class complement inhibitor, eculizumab, in 2007. This anti-complement C5 therapy resulted in the stabilization of many hematologic parameters and dramatically reduced the often fatal, coagulant-resistant thrombotic events. Despite the remarkable clinical success, a substantial proportion of PNH patients experience suboptimal clinical responses during anti-C5 therapy. We describe the identification and mechanistic dissection of four unexpected processes responsible for such suboptimal clinical responses: (1) pharmacokinetic and (2) pharmacodynamic intravascular breakthrough hemolysis, (3) continuing low-level residual intravascular hemolysis, and (4) extravascular hemolysis. Novel complement therapeutics mainly targeting different complement proteins proximal in the cascade attempt to address these remaining problems. With five approved complement inhibitors in the clinic and many more being evaluated in clinical trials, PNH remains one of the complement diseases with the highest intensity of clinical research. Mechanistically unexpected breakthrough events occur not only with C5 inhibitors but also with proximal pathway inhibitors, which require further mechanistic elaboration.

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.

What we know and what we don't know about catastrophic antiphospholipid syndrome.

Catastrophic antiphospholipid syndrome (CAPS) is a severe condition with high mortality. Since its description in 1992, an important effort has been made to improve and disseminate knowledge on CAPS. Most of our current knowledge comes from the studies performed using the CAPS Registry, a database created in 2000 to gather as many cases as possible in order to better define this disease. It has demonstrated that this condition has multiple faces and is often triggered by a precipitating factor that leads to a thrombotic microangiopathy and cytokine storm involving almost any organ of the body. Analysis of the CAPS Registry has also shown that patients receiving anticoagulation, glucocorticoids and plasma exchange and/or IVIG have a better prognosis. However, there are still many unresolved questions. In this review we summarize what is known and what is still a matter of research in this condition.

Relapsing meningitis and limbic encephalitis in anti-AQP4-Ab-associated neuromyelitis optica spectrum disorder.

OBJECTIVES: neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease mainly affecting optic nerves and the spinal cord. Due to the potentially irreversible tissue damage, prevention of relapses is of utmost importance. METHODS: We describe the atypical clinical course and pathology results of a patient with anti-aquaporin-4 antibody (anti-AQP4-Ab)-associated NMOSD who developed aseptic meningitis followed by limbic-encephalitis-like presentation with extensive brain lesions upon treatment with rituximab and tocilizumab. RESULTS: The patient developed subacute cognitive decline with magnetic resonance imaging (MRI) evidence of extensive brain white matter lesions. In the hypothesis of an opportunistic brain infection, she underwent brain biopsy of the temporal pole. Pathology results revealed typical NMOSD findings with complement activation, supporting the hypothesis of an atypical presentation of anti-AQP-Ab-associated NMOSD. Accordingly, treatment with the complement-targeting drug eculizumab was started, leading to a dramatic clinical and MRI improvement. DISCUSSION: aseptic meningitis and limbic encephalitis could represent a rare phenotype of anti-AQP4-Ab-associated NMOSD.

Novel uses of complement inhibitors in myasthenia gravis-Two case reports.

INTRODUCTION/AIMS: Myasthenia gravis (MG) is a rare, life-threatening immune-related adverse effect (irAE) of immune checkpoint inhibitor (ICI) treatment. C5-complement inhibitors are effective treatments for acetylcholine receptor antibody (AChR ab) positive generalized MG. We describe the use of eculizumab/ravulizumab in two patients with MG receiving concomitant pembrolizumab. METHODS: This was a retrospective review of two medical records. RESULTS: Patient 1: An 80-year-old male with recurrent, non-muscle invasive transitional cell carcinoma of the bladder developed ICI-induced AChR ab positive MG (ICI-MG), myositis, and myocarditis 2 weeks after the first dose of pembrolizumab. Myositis responded to corticosteroids. MG responded to eculizumab, followed by ravulizumab. He died of metastatic cancer 8 months later. Patient 2: A 58-year-old male had refractory thymoma-associated AChR ab-positive MG, which responded to eculizumab. He developed metastatic Merkel cell cancer necessitating pembrolizumab. MG remained stable on eculizumab. He had no irAEs for 22 months, with positron emission tomographic resolution of cancer. He then developed mild, indolent retinal vasculitis, which responded to prednisone. Discontinuation of pembrolizumab for 5 months resulted in cancer recurrence; pembrolizumab was resumed with peri-infusion pulse prednisone. MG remained stable and he continues eculizumab. DISCUSSION: In the first patient, eculizumab, followed by ravulizumab, improved ICI-MG. In the second patient, eculizumab treatment may have had a prophylactic effect on the development of ICI-induced irAEs. The effect of complement inhibition on cancer outcomes of ICI therapy is unknown. A possible biologic basis for complement inhibitors in reducing irAEs of ICI, especially in the presence of underlying autoimmune disease, merits evaluation.

Carfilzomib-associated thrombotic microangiopathy: clinical features and outcomes.

BACKGROUND AND HYPOTHESIS: Carfilzomib, a new proteasome inhibitor indicated for patients with relapsed/refractory myeloma, has been associated with cases of thrombotic microangiopathy (CFZ-TMA). The role of variants in the complement alternative pathway and therapeutic potential of complement blockade with eculizumab remain to be determined. METHODS: We report 37 cases of CFZ-TMA recorded in the French reference center for TMA with their clinical characteristics, genetic analysis and outcome according to treatments. RESULTS: A trigger was identified in more than half of cases, including 8 influenza and 5 SARS-CoV-2 cases. All patients presented with acute kidney injury (AKI) (KDIGO stage 3 in 31 (84%) patients) while neurological (n=13, 36%) and cardiac damage (n=7, 19%) were less frequent. ADAMTS13 and complement activity were normal (n= 28 and 18 patients tested) and no pathogenic variant in the alternative complement pathway was found in 7 patients tested.TMA resolved in most (n=34, 94%) patients but 12 (44%) still displayed stage 3 AKI at discharge. Nineteen (51%) patients were treated with therapeutic plasma exchange, 14 (38%) patients received corticosteroids and 18 (50%) were treated with eculizumab. However none of these treatments demonstrated a significant impact on outcomes. CONCLUSION: This study is the largest case series of CFZ-TMA since its approval in 2012. Patients present with severe AKI and experience frequent sequelae. Complement variants and blockade therapy do not seem to play a role in the pathophysiology and prognosis of the disease.

Eculizumab dose tapering should take into account the nonlinearity of its pharmacokinetics.

AIMS: Eculizumab is a monoclonal antibody targeting complement protein C5 used in renal diseases. As recommended dosing regimen leads to unnecessarily high concentrations in some patients, tailored dosing therapeutic drug monitoring was proposed to reduce treatment cost. The objectives of the present work were (i) to investigate the target-mediated elimination of eculizumab and (ii) whether a pharmacokinetic model integrating a nonlinear elimination allows a better prediction of eculizumab concentrations than a linear model. METHODS: We analysed 377 eculizumab serum concentrations from 44 patients treated for atypical haemolytic uraemic syndrome and C3 glomerulopathy with a population pharmacokinetic approach. Critical concentrations (below which a non-log-linear decline of concentration over time is evidenced) were computed to estimate the relevance of the target-mediated elimination. Simulations of dosing regimens were then performed to predict probabilities of target attainment (i.e. trough >100 mg/L). RESULTS: Pharmacokinetics of eculizumab was nonlinear and followed a mixture of first-order (CL = 1.318 mL/day/kg) and Michaelis-Menten elimination (Vmax = 26.07 mg/day, Km = 24.06 mg/L). Volume of distribution (72.39 mL/kg) and clearance were weight-dependent. Critical concentrations (Vmax/CL) ranged from 144.7 to 759.7 mg/L and were inversely related to body weight (P = .013). Nonlinearity was thus noticeable at therapeutic concentrations. Simulations predicted that 1200 mg of eculizumab every 21 days would allow 85% and 76% of patients to maintain a therapeutic exposure, for 50 or 90 kg body weight, respectively. CONCLUSIONS: Our study investigates the nonlinear elimination of eculizumab and discusses the importance of accounting for eculizumab target-mediated elimination in therapeutic drug monitoring.

The role of anticomplement therapy in the management of the kidney allograft.

As the number of patients living with kidney failure grows, the need also grows for kidney transplantation, the gold standard kidney replacement therapy that provides a survival advantage. This may result in an increased rate of transplantation from HLA-mismatched donors that increases the rate of antibody-mediated rejection (AMR), which already is the leading cause of allograft failure. Plasmapheresis, intravenous immunoglobulin therapy, anti-CD20 therapies (i.e., rituximab), bortezomib and splenectomy have been used over the years to treat AMR as well as to prevent AMR in high-risk sensitized kidney transplant recipients. Eculizumab and ravulizumab are monoclonal antibodies targeting the C5 protein of the complement pathway and part of the expanding field of anticomplement therapies, which is not limited to kidney transplant recipients, and also includes complement-mediated microangiopathic hemolytic anemia, paroxysmal nocturnal hemoglobinuria, and ANCA-vasculitis. In this narrative review, we summarize the current knowledge concerning the pathophysiological background and use of anti-C5 strategies (eculizumab and ravulizumab) and C1-esterase inhibitor in AMR, either to prevent AMR in high-risk desensitized patients or to treat AMR as first-line or rescue therapy and also to treat de novo thrombotic microangiopathy in kidney transplant recipients.

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

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

Efficacy and safety of eculizumab in Guillain-Barré syndrome: A phase 3, multicenter, double-blind, randomized, placebo-controlled clinical trial.

BACKGROUND AND AIMS: Guillain-Barré syndrome (GBS) is an acute, self-limited, immune-mediated peripheral neuropathy. Current treatments for GBS include intravenous immunoglobulin (IVIg) and plasma exchange, which may not sufficiently benefit severely affected patients. This study evaluated the efficacy and safety of eculizumab add-on therapy to IVIg (standard-of-care treatment) in patients with severe GBS. METHODS: This phase 3, multicenter, double-blind, randomized, placebo-controlled clinical trial (NCT04752566), enrolled Japanese adults (age ≥ 18 years) with severe GBS (Hughes functional grade [FG] score FG3 or FG4/FG5 within 2 weeks of onset of GBS). Participants were randomized 2:1 to receive intravenous infusion of eculizumab or placebo (once weekly for 4 weeks) with IVIg treatment with 20 weeks of follow-up. Primary efficacy endpoint was the time to first reach FG score ≤1 (able to run). Key secondary endpoints were proportion of participants achieving FG ≤1 at weeks 8 and 24 and FG improvement ≥3 at week 24. Pharmacodynamic analysis of serum free C5 concentration over time was performed. Safety was evaluated. RESULTS: The analysis included 57 participants (eculizumab, n = 37; placebo, n = 20). Primary endpoint was not achieved (hazard ratio, 0.9; 95% CI, 0.45-1.97; p = .89). Key secondary endpoints did not reach statistical significance. Serum C5 concentration was reduced by 99.99% at 1 h postdose and sustained to week 5 but returned to baseline at the end of follow-up period. No new safety signals for eculizumab were identified. INTERPRETATION: Although well tolerated, eculizumab treatment did not show significant effects on motor function recovery compared to placebo in patients with GBS.

Successful use of eculizumab in immediate ANCA vasculitis recurrence in a pediatric kidney transplant.

BACKGROUND: Kidney transplantation is an acceptable therapy end-stage kidney disease secondary to antineutrophil cytoplasmic antibody-associated vasculitis with risk of disease recurrence ranging from 3% to 17%. Standard posttransplant immunosuppression is the mainstay of therapy after recurrence. Recently, new medications focused on complement regulation and avoidance of steroids have been shown to be effective in treating antineutrophil cytoplasmic antibody (ANCA) vasculitis with no studies in the pediatric population. METHODS: We report a 5-year-old patient with immediate recurrence of positive myeloperoxidase (MPO)-ANCA vasculitis after deceased donor kidney transplant and the novel use of eculizumab to salvage the graft. RESULTS: Eculizumab and transition to ravulizumab has been successful in improving graft function and maintenance of disease remission after immediate MPO-ANCA vasculitis recurrence posttransplant. CONCLUSIONS: Complement inhibitors may be used in addition to standard immunosuppression postkidney transplant in a pediatric patient with MPO-ANCA vasculitis recurrence without higher rates of infections.

Population pharmacokinetic, pharmacodynamic and efficacy modeling of SB12 (proposed eculizumab biosimilar) and reference eculizumab.

PURPOSE: To describe, compare similarity of pharmacokinetic (PK), pharmacodynamic (PD) and efficacy of SB12 and reference eculizumab (ECU) and find clinically significant covariate relationships. METHODS: The PK, PD (terminal complement activity) and efficacy (LDH) data of SB12 and ECU were obtained from 289 subjects from phase I and phase III studies. One- and two-compartment PK models with first-order elimination were evaluated for SB12 and ECU. For PD and efficacy, both direct and indirect models were tested. The impact of covariates on PK, PD and efficacy parameters was assessed. Relationship between PK/PD and PD/efficacy was characterized. This modeling was performed using NONMEM version 7.4 (Icon Development Solutions, Ellicott City, MD, USA). RESULTS: The two-compartment model adequately described the PK of SB12 and ECU, and the subject's weight was chosen as a clinically significant covariate affecting drugs' clearance and central volume of distribution. Treatment group was not a significant covariate affecting clearance. The direct response model using inhibitory sigmoid Emax and sigmoid Emax relationship well described the PK/PD relationship and PD/efficacy relationship of SB12 and ECU, respectively. Through this modeling, the relationships between PK, PD and efficacy were characterized. There were no differences in PK, PD and efficacy parameters between SB12 and ECU in pooled populations of healthy subjects and paroxysmal nocturnal haemoglobinuria (PNH) patients. CONCLUSION: The population modeling showed PK, PD and efficacy similarities between SB12 and ECU in pooled population of healthy subjects and PNH patients, supporting the totality of evidence on biosimilarity for SB12.

Anti-CFH-associated hemolytic uremic syndrome: do we still need plasma exchange?

BACKGROUND: Between 5 and 50% of atypical hemolytic uremic syndrome (aHUS) cases in children are caused by autoantibodies against complement factor H (CFH). Given the acquired autoimmune nature of the disease, plasma exchange (PE) and various immunosuppressive treatments have been used. More recently, eculizumab has been proposed. METHODS: In this multicenter, retrospective study, we report outcomes of 12 children with anti-FH antibody-associated HUS treated with eculizumab associated with various immunosuppressive regimens. RESULTS: Patients were treated with eculizumab for 15.5 [9.5;23.0] months and 3 received PE or IgG adsorption. Three patients received mycophenolate mofetil (MMF) alone, 1 patient received MMF and steroids, 1 patient received MMF and rituximab, 3 patients received MMF/steroids and rituximab, and 4 patients did not receive any immunosuppression. Anti-FH antibody levels significantly decreased but no difference was observed based on the immunosuppressive regimen. Eculizumab was discontinued in 7/10 patients after 11 [7.5;15.5] months and MMF in 6/8 patients after 36 [35;40] months. Anti-FH titers at MMF discontinuation ranged from 257 to 3425 UI/L. None of these patients relapsed and eGFR at last follow-up was above 70 mL/min/1.73 m2 in all patients. CONCLUSIONS: Eculizumab is effective and safe in inducing and maintaining remission in aHUS secondary to anti-FH antibodies and renders reduction of anti-FH titers less urgent. Anti-FH antibody titers decreased in most patients irrespective of the immunosuppressive treatment chosen, so that a strategy consisting of combining eculizumab with MMF monotherapy seems sufficient at least in non-Indian or less severe forms of anti-FH antibody-associated HUS.

Protein-losing enteropathy as a new phenotype in atypical hemolytic uremic syndrome caused by CD46 gene mutation.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy. Genetic defects in the alternative complement (AP) pathway have been identified in 60-70% of individuals. Eculizumab is recommended as a first-line therapy. METHODS: We collected the clinical data of a pediatric patient with aHUS accompanied by protein-losing enteropathy (PLE). Genetic testing was performed. Related literature on aHUS combined with PLE was reviewed. RESULTS: A 15-year-old Chinese girl was diagnosed with aHUS at 3.7 years of age and experienced five episodes; her symptoms completely resolved with plasma treatment. Severe gastrointestinal symptoms and hypoalbuminemia presented after the first episode, and PLE was diagnosed. A novel homozygous CD46 variant was identified, and FACS revealed significantly decreased CD46 expression. She presented at a recent relapse with persistent GI symptoms and headache and progressed to chronic kidney failure; peritoneal dialysis was initiated. Eculizumab was given 8 months after the last recurrence. Surprisingly, PLE was cured. Afterward, dialysis was discontinued, and eGFR recovered to 44.8 ml/min/1.73 m2. A review of the literature indicated that PLE with thrombosis was caused by CD55 variants via hyperactivation of the AP system. We report an aHUS patient with PLE caused by CD46 variants. Symptoms of both PLE and aHUS were significantly alleviated in our patient and patients with CD55 variants treated with eculizumab, indicating that PLE was a new symptom of aHUS in our patient with a CD46 variant. CONCLUSIONS: Our case expands the phenotype of aHUS caused by a CD46 mutation and provides evidence of the efficacy of eculizumab after a long phase of chronic kidney failure.

Therapeutic challenges and unmet needs in the management of myasthenia gravis: an Italian expert opinion.

Myasthenia gravis (MG) is a rare, autoimmune, neurological disorder. Most MG patients have autoantibodies against acetylcholine receptors (AChRs). Some have autoantibodies against muscle-specific tyrosine kinase (MuSK) or lipoprotein-receptor-related protein 4 (LRP4), and some are seronegative. Standard of care, which includes anti-cholinesterase drugs, thymectomy, corticosteroids (CS), and off-label use of non-steroidal immunosuppressive drugs (NSISTs), is bounded by potential side effects and limited efficacy in refractory generalized MG (gMG) patients. This highlights the need for new therapeutic approaches for MG. Eculizumab, a monoclonal antibody that inhibits the complement system, has been recently approved in Italy for refractory gMG. A panel of 11 experts met to discuss unmet therapeutic needs in the acute and chronic phases of the disease, as well as the standard of care for refractory patients. Survival was emphasized as an acute phase outcome. In the chronic phase, persistent remission and early recognition of exacerbations to prevent myasthenic crisis and respiratory failure were considered crucial. Refractory patients require treatments with fast onset of action, improved tolerability, and the ability to slow disease progression and increase life expectancy. The Panel agreed that eculizumab would presumably meet the therapeutic needs of many refractory gMG patients. The panel concluded that the unmet needs of current standard of care treatments for gMG are significant. Evaluating new therapeutic options accurately is essential to find the best balance between efficacy and tolerability for each patient. Collecting real-world data on novel molecules in routine clinical practice is necessary to address unmet needs.

Eculizumab for myasthenic exacerbation during treatment with immune-checkpoint inhibitors.

OBJECTIVE: To test the complement inhibitor eculizumab in the treatment of MG exacerbation during therapy with the immune-checkpoint inhibitor (ICI) pembrolizumab, avoiding its discontinuation, which could be detrimental to oncologic course. METHODS: A 76-year-old male with non-thymomatous generalized anti-AchR + MG (MGFA class IVB), during treatment with pembrolizumab for colorectal cancer, developed a severe myasthenic exacerbation, refractory to steroids and IvIg. Eculizumab was started, without pembrolizumab discontinuation. The patient was prospectively followed using MGFA, MG Activities of Daily Living (MG-ADL), Quantitative MG (QMG), MG Composite (MGC), and MG Quality of Life 15 (MG-QOL-15). RESULTS: After an 18-week follow-up, the patient presented a progressive improvement in scores on all scales, achieving a MGFA class IIIB. The percentage improvement was 40% in MG-ADL, 36% in MG Composite, and about 30% in QMG. Bulbar symptoms improved by about 70% in MG-ADL and MG Composite and 40% in QMG. Eculizumab was well tolerated and pembrolizumab regularly continued, with a good control of cancer progression. DISCUSSION: Eculizumab potentially offers a mechanism-based treatment of MG in patients under anti-programmed cell death protein 1 (PD-1) agents, without interfering with their mechanism of action and avoiding their discontinuation. Larger case series deserve to be evaluated.

Systemic lupus erythematosus presenting with atypical hemolytic uremic syndrome: a case report and review of the literature.

Systemic lupus erythematosus (SLE) can present with a diverse array of hematologic manifestations, among which atypical hemolytic uremic syndrome (aHUS) is a rare entity. SLE-triggered aHUS has significant morbidity and mortality without timely intervention, yet its frequency remains uncertain and optimal strategies for complement-directed therapies are largely expert-driven. We performed a comprehensive literature review and present a case of a 23-year-old female newly diagnosed with SLE/class IV lupus nephritis who developed aHUS that rapidly responded to the C5 antagonist, eculizumab. Review of the current literature identified forty-nine published cases of SLE with concurrent aHUS and revealed a predilection for aHUS in younger SLE patients, concurrent presentation with lupus nephritis, anti-dsDNA positivity, and complement system abnormalities. Over seventy percent of cases used eculizumab as complement-directed therapy with a trend towards faster time to improvement in laboratory parameters, though reported outcomes were highly variable. Early recognition of aHUS in SLE is pivotal in guiding appropriate therapeutic interventions, and prompt initiation of eculizumab may reduce the potential morbidity associated with plasmapheresis and additional immunosuppression. While eculizumab showcases promising results, its optimal timing and duration remain elusive. An understanding of a patients' complement genetics could aid management strategies, and ongoing research into complement-targeted therapies offers promising avenues for both SLE and aHUS treatment.

Clinical efficacy and safety of switching from eculizumab to ravulizumab in adult patients with aHUS- real-world data.

BACKGROUND: The complement factor 5 (C5)-inhibitor eculizumab has been established as standard-of-care for the treatment of atypical hemolytic uremic syndrome (aHUS). In 2021, the long-acting C5-inhibitor ravulizumab was approved, extending intervals of intravenous treatment from two to eight weeks resulting in improvement of quality of life for patients and lowering direct and indirect therapy associated costs. METHODS: This multicenter, retrospective data analysis of 32 adult patients with aHUS (including 10 kidney transplant recipients) treated with eculizumab for at least three months and switched to ravulizumab aims to evaluate the safety and efficacy of switching medication in the real-world setting. Hematologic parameters, kidney function, concurrent therapy and aHUS associated events were evaluated three months before and until up to 12 months after switching to ravulizumab. RESULTS: Mean age (range) at ravulizumab initiation was 41 years (19-78 years) and 59% of the patients were female. Genetic analysis was available for all patients with 72% showing a pathogenic variant. Median time (range) on eculizumab before switching was 20 months (3-120 months). No new events of TMA or worsening of renal function were reported during up to 12 months of follow-up during ravulizumab treatment. CONCLUSIONS: This is the largest, non-industry derived, multi-center retrospective analysis of adult patients with aHUS switching C5-inhibitor treatment from eculizumab to ravulizumab in the real-world setting. Switching to ravulizumab was safe and efficient resulting in sustained hematological stability and preservation of renal function.

mRNA-LNP COVID-19 Vaccine Lipids Induce Complement Activation and Production of Proinflammatory Cytokines: Mechanisms, Effects of Complement Inhibitors, and Relevance to Adverse Reactions.

A small fraction of people vaccinated with mRNA-lipid nanoparticle (mRNA-LNP)-based COVID-19 vaccines display acute or subacute inflammatory symptoms whose mechanism has not been clarified to date. To better understand the molecular mechanism of these adverse events (AEs), here, we analyzed in vitro the vaccine-induced induction and interrelations of the following two major inflammatory processes: complement (C) activation and release of proinflammatory cytokines. Incubation of Pfizer-BioNTech's Comirnaty and Moderna's Spikevax with 75% human serum led to significant increases in C5a, sC5b-9, and Bb but not C4d, indicating C activation mainly via the alternative pathway. Control PEGylated liposomes (Doxebo) also induced C activation, but, on a weight basis, it was ~5 times less effective than that of Comirnaty. Viral or synthetic naked mRNAs had no C-activating effects. In peripheral blood mononuclear cell (PBMC) cultures supplemented with 20% autologous serum, besides C activation, Comirnaty induced the secretion of proinflammatory cytokines in the following order: IL-1α < IFN-γ < IL-1ß < TNF-α < IL-6 < IL-8. Heat-inactivation of C in serum prevented a rise in IL-1α, IL-1ß, and TNF-α, suggesting C-dependence of these cytokines' induction, although the C5 blocker Soliris and C1 inhibitor Berinert, which effectively inhibited C activation in both systems, did not suppress the release of any cytokines. These findings suggest that the inflammatory AEs of mRNA-LNP vaccines are due, at least in part, to stimulation of both arms of the innate immune system, whereupon C activation may be causally involved in the induction of some, but not all, inflammatory cytokines. Thus, the pharmacological attenuation of inflammatory AEs may not be achieved via monotherapy with the tested C inhibitors; efficacy may require combination therapy with different C inhibitors and/or other anti-inflammatory agents.