Complement-mediated Hemolysis Research Articles

Real-World Study of US Adults with Paroxysmal Nocturnal Hemoglobinuria Treated with Pegcetacoplan

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, life-threatening disease characterized by complement-mediated hemolysis. OPERA is the first US longitudinal real-world study on C3 inhibitor therapy, known as pegcetacoplan. Methods: OPERA enrolled US patients with PNH, age ≥18, who were prescribed pegcetacoplan, and data were collected from routine care. Hemoglobin was reported by patients during regular follow-up (censored from transfusions). The Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue (0–52 score) and Patient-Reported Outcomes Measurement Information System scale for Cognitive Function Abilities (PROMIS-CF; 23.27–67.09 t-score) were completed electronically (low score = negative outcome). Patients self-reported incidence of healthcare resource utilization (HCRU). Results: By January 2024, 70 patients (mean age 44.6 years; 57.1% female) reported up to 9 months of pegcetacoplan treatment, with a median [IQR] follow-up of 6.6 [3.8] months. The latest reported hemoglobin levels improved by a mean (SD) of 2.6 (1.9) g/dL from baseline. At 3, 6 and 9 months, patients reported clinically meaningful improvements (≥5 points) in FACIT-F (53.3–69.0%) and (≥2 points) PROMIS-CF (46.7–55.2%). Patients reported a <10% incidence rate per person month of all HCRU events. Conclusions: This first longitudinal real-world US study indicates a positive trend in Hb, fatigue, and cognition with limited HCRU during pegcetacoplan treatment in adults with PNH.

Human-factors validation study for a wearable, single-use injector for patients with paroxysmal nocturnal hemoglobinuria

Pegcetacoplan is a complement component 3 inhibitor approved to treat adults with paroxysmal nocturnal hemoglobinuria, a rare disease characterized by life-threatening complement-mediated hemolysis (often leading to anemia) and thrombosis. Pegcetacoplan is self-administered as a subcutaneous (SC) injection with an at-home infusion pump. A newly approved, more convenient, wearable, single-use automatic injector was evaluated in a human factors study for the safe and effective SC delivery of pegcetacoplan in the abdominal area. Adult patients with anemia (representative of PNH) and caregivers (n=15 each) received formal injector use training (2-hour session followed by 1-hour decay) and reviewed the instructions for use (IFU), whereas health care providers (HCPs; n=15) only received the IFU. Participants completed a use test, knowledge-based assessment (KBA), and interviews. Forty-four of 45 participants (98%) passed the use test. Residual risks from observed errors (17 critical use and 6 KBA errors) were deemed acceptable. This study validated the injector for ease of use and safe and effective SC delivery of pegcetacoplan at home, which may potentially reduce treatment burden for patients with PNH.

Sutimlimab for Cold Agglutinin Disease.

Cold agglutinin disease (CAD) is a rare type of autoimmune hemolytic anemia (AIHA) distinct from warm antibody AIHA. One of the ways it is distinct is that CAD is usually not responsive to corticosteroids compared with warm antibody AIHA. Historically, CAD therapy has been limited to immunotherapy or chemoimmunotherapy with varying responses. Cold agglutinin disease also poses a risk for thrombosis and mortality. For patients, fatigue tends to be a common symptom of CAD. The hallmark of CAD is complement-mediated hemolysis, which makes complement inhibitors a critical therapeutic option for patients. Previously, eculizumab, a C5 inhibitor, had limited therapeutic effect for CAD. More recently, sutimlimab, a C1s inhibitor, was shown in two phase III studies to be an efficacious treatment for CAD, improving hemoglobin, hemolysis, and fatigue. However, there is a paucity of medical literature on CAD and on sutimlimab in particular that is geared toward advanced practice providers (APPs). This article aims to provide APPs with a background in CAD and a focus on sutimlimab, assisting these providers in caring for patients with CAD receiving this therapy.

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.

Iptacopan Efficacy and Safety to Treat Paroxysmal Nocturnal Hemoglobinuria (PNH): A Systematic Review and Meta-Analysis.

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon blood condition caused by complement-mediated hemolysis. In early clinical studies, iptacopan, an oral factor B inhibitor, showed promise in treating PNH. This systematic review aimed to compile information on the effectiveness and safety of iptacopan for PNH.A systematic review was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. The Medline, Embase, PubMed, and Cochrane Central databases were searched for randomized controlled trials (RCTs) and observational studies that evaluated iptacopan for PNH. The primary efficacy outcomes were hemoglobin and lactate dehydrogenase (LDH) changes. A fixed-effects model was used for the meta-analysis. Six studies (three prospective cohorts, two RCTs, and one non-randomized trial) were included, comprising 197 patients. Iptacopan therapy significantly increased hemoglobin levels (mean differences (MD) = 12.98 g/L; 95% CI: 11.82-14.13; p < 0.0001) and decreased LDH (MD = -83.55 IU/L; 95% CI: -83.77 to -83.34; p < 0.0001). Subgroup analyses revealed more significant hemoglobin increases in European vs. Asian populations, studies with baseline Hb > 10 g/dL vs. < 10 g/dL, and studies lasting > 24 weeks vs. ≤ 24 weeks. LDH decreases were more pronounced in studies with baseline LDH > 500 IU/L vs. < 500 IU/L. The incidence of adverse events ranged from 66% to 90%, with the most common being headache, nasopharyngitis, and diarrhea. Serious adverse events occurred in 0-20% of patients across studies. Only one patient withdrew because adverse effects were reported across all studies.Preliminary data support iptacopan's effectiveness in improving hemoglobin levels and lowering hemolysis in PNH, both as a monotherapy and in combination with usual treatment. The safety profile appears to be excellent, with a minimal incidence of major adverse events and treatment discontinuation. Further studies are needed to validate the effectiveness and safety of larger, longer-term trials. Iptacopan is a viable oral therapy option for PNH.

Relationship between serum uric acid levels and complement functional activity

Uric acid (UA) is the end product of purine metabolism and a substance that promotes a chronic inflammatory process. One of the mechanisms of inflammation associated with the UA is the ability of its crystals, mainly monosodium urate, to activate NLRP3 inflammasomes, classifying UA and its salt crystals as damage-related molecular patterns (DAMPs). These crystals also activate the complement system, leading to increase in C3a, C4a, and C5a concentrations and excessive consumption of complement system proteins. It has been known for a long time that UA is able to activate complement, but the relationship between hyperuricemia and complement system functional activity, which can be assessed by complement-mediated hemolysis, remains unclear. In this study, we have made an attempt to estimate the UA concentration that does not lead to spontaneous complement system activation. The study assessed the relationships between the parameters of complement functional activity and some blood biochemical data with UA concentration ([UA]) using correlation analysis. The rate (Vlys) and time of 50% hemolysis (T50) were considered as indicators of complement functional activity, and their relationship was demonstrated using exponential functions y = a*e[x], which takes the form y = [UA]*e[C3]. Concentration of C3 is the argument of the function, base of degree is the base of the natural logarithm, and the proportionality coefficient equal to the UA concentration. Correlation analysis showed the inverse dependent between function values and the corresponding values of T50 (r = -0.83, p 0.0001) in the range of UA concentration exceeding 370 umol/L, which is near to the upper limit of the normal level for women and is within the normal range for men. Thus, the approach to assess the effect of UA on complement activation using the analysis of the complement hemolytic activity is effective to demonstrate the pathogenetic function of UA in the development of the inflammatory process without involving inflammasomes through the direct effects on complement activation processes. The relationships demonstrated suggest that the upper limits of the range of “normal” UA concentrations are arbitrary, and their revision is likely advisable.

Three Years On: The Role of Pegcetacoplan in Paroxysmal Nocturnal Hemoglobinuria (PNH) since Its Initial Approval.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease characterized by complement-mediated hemolysis and potentially life-threatening complications. Pegcetacoplan, an inhibitor of complement components C3 and C3b, was approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) in 2021. A recent expansion to its indication by the EMA has made pegcetacoplan available for the treatment of both complement inhibitor-naïve and -experienced patients with PNH who have hemolytic anemia, a similarly broad patient population as in the US. This approval was based on results from the Phase 3 PEGASUS study, where pegcetacoplan showed superiority over the C5 inhibitor eculizumab with regard to improving the hemoglobin level in patients with anemia despite eculizumab treatment, and the Phase 3 PRINCE study, where pegcetacoplan showed superiority over supportive care with regard to hemoglobin stabilization and improving the lactate dehydrogenase level in complement inhibitor-naïve patients. In light of this recent indication expansion by the EMA, this article describes how the strong efficacy of pegcetacoplan is linked to its mechanism of action, which provides broad hemolysis control over both intravascular and extravascular hemolysis to improve a range of disease markers and enhance patients' quality of life. Furthermore, additional data and learnings obtained from over 3 years of experience with pegcetacoplan are summarized, including long-term efficacy and safety results, real-world clinical experiences, pharmacokinetic characteristics, and extensive practical guidance for the first-to-market proximal complement inhibitor for PNH.

Moving toward Individual Treatment Goals with Pegcetacoplan in Patients with PNH and Impaired Bone Marrow Function.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, potentially life-threatening haematological disease characterised by chronic complement-mediated haemolysis with multiple clinical consequences that impair quality of life. This post hoc analysis assessed haematological and clinical responses to the first targeted complement C3 inhibitor pegcetacoplan in patients with PNH and impaired bone marrow function in the PEGASUS (NCT03500549) and PRINCE (NCT04085601) studies. For patients with impaired bone marrow function, defined herein as haemoglobin <10 g/dL and absolute neutrophil count <1.5 × 109 cells/L, normalisation of the parameters may be difficult. Indeed, 20% and 43% had normalised haemoglobin in PEGASUS and PRINCE, respectively; 60% and 57% had normalised LDH, and 40% and 29% had normalised fatigue scores. A new set of parameters was applied using changes associated with clinically meaningful improvements, namely an increase in haemoglobin to ≥2 g/dL above baseline, decrease in LDH to ≤1.5× the upper limit of normal, and an increase in fatigue scores to ≥5 points above baseline. With these new parameters, 40% and 71% of PEGASUS and PRINCE patients had improved haemoglobin; 60% and 71% had an improvement in LDH, and 60% and 43% had an improvement in fatigue scores. Thus, even patients with impaired bone marrow function may achieve clinically meaningful improvements with pegcetacoplan.

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.

Acute paroxysmal cold hemoglobinuria upon dengue fever: A case report

Rationale: Dengue fever is capable of inciting the formation of transient polyclonal antibodies directed at red blood cell antigens, resulting in complement-mediated hemolysis, leading to intravascular hemolysis and hemoglobinuria. Patient’s concern: A 12-year-old male patient who recovered from dengue fever a week ago had red blood cell agglutination, spherocytes, and engulfment of red blood cells (erythrophagocytosis) by monocytes and neutrophils on routine hematological peripheral blood smear. The unexpected blood smear results prompted the lab physicians to investigate autoimmune hemolytic anemia, which revealed a monospecific positive direct antiglobulin test for complement (C3d, C3b) and the presence of Donath-Landsteiner antibody. Diagnosis: Paroxysmal cold hemoglobinuria (PCH), secondary to dengue fever. Interventions: Oxygen supplements, antibiotics, intravenous immunoglobulins, steroid therapy, and packed cell transfusions were administered. Outcomes: The patient’s condition was improved following the therapy. Lessons: Post-dengue PCH is a rare complication that requires a thorough peripheral smear examination for erythrophagocytosis, as advanced hematology analyzers fail to detect such findings.

Cost-effectiveness of sutimlimab in cold agglutinin disease.

Primary cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia caused by cold-reactive antibodies that bind to red blood cells and lead to complement-mediated hemolysis. Patients with primary CAD experience the burden of increased health resource utilization and reduced quality of life. The standard-of-care (SOC) in patients with primary CAD has included cold avoidance, transfusion support, and chemoimmunotherapy. The use of sutimlimab, a humanized monoclonal antibody that selectively inhibits C1-mediated hemolysis, was shown to reduce transfusion-dependence and improve quality of life across two pivotal phase 3 studies, further supported by 2-year extension data. Using data from the transfusion-dependent patient population that led to sutimlimab's initial FDA approval, we performed the first-ever cost-effectiveness analysis in primary CAD. The projected incremental cost-effectiveness ratio (ICER) in our Markov model was $2 340 000/QALY, significantly above an upper-end conventional US willingness-to-pay threshold of $150 000/QALY. These results are consistent across scenarios of higher body weight and a pan-refractory SOC patient phenotype (i.e., treated sequentially with bendamustine-rituximab, bortezomib, ibrutinib, and eculizumab). No parameter variations in deterministic sensitivity analyses changed our conclusion. In probabilistic sensitivity analysis, SOC was favored over sutimlimab in 100% of 10 000 iterations. Exploratory threshold analyses showed that significant price reduction (>80%) or time-limited treatment (<18 months) followed by lifelong clinical remission off sutimlimab would allow sutimlimab to become cost-effective. The impact of sutimlimab on health system costs with longer term follow-up data merits future study and consideration through a distributional cost-effectiveness framework.

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.

Safety and Efficacy of Pegcetacoplan in Adult Patients with Paroxysmal Nocturnal Hemoglobinuria over 48Weeks: 307 Open-Label Extension Study.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, life-threatening disease characterized by complement-mediated hemolysis and thrombosis. Pegcetacoplan, the first targeted complement component3 (C3) PNH therapy, was safe and efficacious in treatment-naive and pre-treated patients with PNH in five clinical trials. The 307 open-label extension (OLE) study (NCT03531255) is a non-randomized, multicenter extension study of long-term safety and efficacy of pegcetacoplan in adult patients with PNH who completed a pegcetacoplan parent study. All patients received pegcetacoplan. Outcomes at the 48-week data cutoff (week48 of 307-OLE or August 27, 2021, whichever was earlier) are reported. Hemoglobin concentrations, Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scores, and transfusion avoidance were measured. Hemoglobin > 12g/dL and sex-specific hemoglobin normalization (i.e., male, ≥ 13.6g/dL; female, ≥ 12g/dL) were assessed as percentage of patients with data available and no transfusions 60days before data cutoff. Treatment-emergent adverse events, including hemolysis, were reported. Data from 137 patients with at least one pegcetacoplan dose at data cutoff were analyzed. Mean (standard deviation [SD]) hemoglobin increased from 8.9 (1.22) g/dL at parent study baseline to 11.6 (2.17) g/dL at 307-OLE entry and 11.6 (1.94) g/dL at data cutoff. At parent study baseline, mean (SD) FACIT-Fatigue score of 34.1 (11.08) was below the general population norm of 43.6; scores improved to 42.8 (8.79) at 307-OLE entry and 42.4 (9.84) at data cutoff. In evaluable patients, hemoglobin > 12g/dL occurred in 40.2% (43 of 107) and sex-specific hemoglobin normalization occurred in 31.8% (34 of 107) at data cutoff. Transfusion was not required for 114 of 137 patients (83.2%). Hemolysis was reported in 23 patients (16.8%). No thrombotic events or meningococcal infections occurred. Pegcetacoplan sustained long-term improvements in hemoglobin concentrations, fatigue reduction, and transfusion burden. Long-term safety findings corroborate the favorable profile established for pegcetacoplan. ClinicalTrials.gov identifier, NCT03531255.

Iptacopan: First Approval.

Iptacopan (FABHALTA®) is an oral complement Factor B inhibitor developed by Novartis Pharmaceuticals for the treatment of complement-mediated diseases. Acting upstream of complement 5 in the alternative pathway, iptacopan inhibits both terminal complement-mediated intravascular haemolysis and complement 3-mediated extravascular haemolysis. On 5 December 2023, iptacopan received approval in the USA for the treatment of adults with paroxysmal nocturnal haemoglobinuria (PNH). This article summarizes the milestones in the development of iptacopan leading to this first approval for PNH.

Expert consensus on the management of pharmacodynamic breakthrough-hemolysis in treated paroxysmal nocturnal hemoglobinuria

ABSTRACT Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, non-malignant hematologic disease characterized by complement-mediated hemolysis (with or without hemoglobinuria), fatigue, increased susceptibility to thrombosis, and bone marrow dysfunction. The development of complement inhibitors has transformed outcomes for patients with PNH, but patients may still experience pharmacodynamic breakthrough hemolysis (BTH), which can be caused by exposure to a complement amplifying condition (CAC), such as vaccination, infection, or surgery. Materials and methods: A 13-member expert panel used a validated methodology (a RAND/UCLA modified Delphi panel) to develop consensus on how to classify pharmacodynamic BTH in patients with complement-inhibitor treated PNH. Physicians reviewed literature, rated the appropriateness of over 400 scenarios, and discussed the ratings at an in-person meeting. Results: After the meeting, the panel agreed on 77% of scenarios. Here, we present the group’s agreed-upon recommendations on how to manage BTH caused by a CAC, as well as provide a severity classification system for BTH and strategies to mitigate risk of BTH in special circumstances (e.g. vaccination, planned or unplanned surgery, and pregnancy). Discussion: In general, as severity of BTH increased, experts agreed more interventions to manage the BTH were appropriate. These recommendations are based on clinical experience and opinion. Without clear data from randomized trials to guide the management of BTH, expert opinion can be useful to support patient care.

In vitro immunoregulatory role of recombinant Ancylostoma ceylanicum calreticulin.

Ancylostoma ceylanicum is a zoonotic soil-derived nematode that parasitizes the intestines of humans and animals (dogs and cats), leading to malnutrition and iron-deficiency anemia. Helminth parasites secrete calreticulin (CRT), which regulates or blocks the host's immune response. However, no data on A. ceylanicum calreticulin (Ace-CRT) are available. We investigated the biological function of recombinant Ace-CRT (rAce-CRT). rAce-CRT showed reliable antigenicity and stimulated the proliferation of mouse splenocytes and canine peripheral blood mononuclear cells. Quantitative reverse-transcription PCR assays revealed that rAce-CRT primarily promoted the expression of T helper 2 cytokines, particularly IL-13, in canine peripheral blood lymphocytes. rAce-CRT inhibited complement-mediated sheep erythrocyte hemolysis in vitro. Our findings indicate that Ace-CRT plays an immunomodulatory role and may be a promising candidate molecule for a hookworm vaccine.

Multisite Thrombosis in a Patient with Paroxysmal Nocturnal Hemoglobinuria

AbstractCase: Paroxysmal nocturnal hemoglobinuria (PNH) is an extremely rare bone marrow disorder caused by acquired mutations in the phosphatidylinositol glycan class A gene, which lead to a partial or total loss of the cellular complement regulators CD55 and CD59.1 In addition to complement-mediated hemolysis and cytopenia, venous and arterial thromboses at multiple and/or unusual sites are a common complication and occur in up to 44% of patients in historic PNH cohorts.1 2

Management of acute breakthrough hemolysis with intensive pegcetacoplan dosing in patients with PNH

AbstractParoxysmal nocturnal hemoglobinuria (PNH) is characterized by complement-mediated intravascular hemolysis leading to anemia, fatigue, and potentially life-threatening thrombotic complications. Breakthrough hemolysis (BTH) was first described in patients with PNH treated with terminal complement C5 inhibitors when intravascular hemolysis reoccurred despite treatment. Pegcetacoplan, the first proximal complement C3 inhibitor, offers broad hemolysis control in patients with PNH. While experience of managing BTH on C5 inhibitors is documented, very limited guidance exists for proximal complement inhibitors. This interim analysis assessed the effect of intensive treatment with pegcetacoplan following an acute BTH event in a subset of patients enrolled in the ongoing open-label extension study of pegcetacoplan in PNH. Thirteen patients with acute BTH included in the analysis received either a single IV dose of 1080 mg (n = 4) or 1080 mg subcutaneous (SC) dosing on 3 consecutive days (n = 9). A potential, clinically-relevant complement-amplifying condition, such as infection or vaccination, was reported in approximately half of the patients experiencing an acute BTH. Lactate dehydrogenase (LDH) levels decreased between day 1 and day 2 in 8 of 12 evaluable patients and in all 13 patients at day 7 to 12. Nine of 13 patients (69%) achieved LDH <2× the upper limit of normal by day 14 to 19. All adverse events associated with the acute BTH event were considered resolved by the investigators. Overall, intensive treatment with pegcetacoplan was safe and well tolerated. These novel data support effective management of acute BTH events in patients on pegcetacoplan with intensive IV or SC pegcetacoplan dosing. This trial was registered at www.clinicaltrials.gov as #NCT03531255.

CL-K1 Promotes Complement Activation and Regulates Opsonophagocytosis of Macrophages with CD93 Interaction in a Primitive Vertebrate.

Collectin is a crucial component of the innate immune system and plays a vital role in the initial line of defense against pathogen infection. In mammals, collectin kidney 1 (CL-K1) is a soluble collectin that has recently been identified to have significant functions in host defense. However, the evolutionary origins of immune defense of CL-K1 and its mechanism in clearance of pathogenic microorganisms remain unclear, especially in early vertebrates. In this study, the Oreochromis niloticus CL-K1 (OnCL-K1) protein was purified and identified, which was capable of binding to two important pathogens of tilapia, Streptococcus agalactiae and Aeromonas hydrophila. Interestingly, OnCL-K1 exhibited direct bactericidal activity by binding to lipoteichoic acid or LPS on cell walls, disrupting the permeability and integrity of the bacterial membrane invitro. Upon bacterial challenge, OnCL-K1 significantly inhibited the proliferation of pathogenic bacteria, reduced the inflammatory response, and improved the survival of tilapia. Further research revealed that OnCL-K1 could associate with OnMASPs to initiate and regulate the lectin complement pathway. Additionally, OnCD93 reduced the complement-mediated hemolysis by competing with OnMASPs for binding to OnCL-K1. More importantly, OnCL-K1 could facilitate phagocytosis by collaborating with cell surface CD93 in a lectin pathway-independent manner. Moreover, OnCL-K1 also promoted the formation of phagolysosomes, which degraded and killed ingested bacteria. Therefore, this study reveals the antibacterial response mechanism of CL-K1 in primitive vertebrates, including promoting complement activation, enhancing opsonophagocytosis, and killing of macrophages, as well as its internal links, all of which provide (to our knowledge) new insights into the understanding of the evolutionary origins and regulatory roles of the collectins in innate immunity.

ПАРОКСИЗМАЛЬНАЯ НОЧНАЯ ГЕМОГЛОБИНУРИЯ (случай из практики)

The non-tumor blood disease paroxysmal nocturnal hemoglobinuria, which develops as a result of acquired mutations in the PIG-A gene, is presented. As a result of mutation, there is a loss of complement-regulating proteins (GPI-AP) on the surface of blood cells (on erythrocytes – CD55, CD59, on granulocytes – CD16, CD24, on monocytes – CD14, CD48). A clone of cells subject to complement-mediated hemolysis is formed. With intravascular hemolysis of erythrocytes, a lot of hemoglobin appears in the bloodstream, then it enters the urine, it darkens. Neutrophils are also destroyed, platelet aggregation increases. Venous and arterial thrombosis can occur throughout the body. The criteria and forms of PNG are described. The clinical manifestations are highlighted, the knowledge of which is necessary for doctors of different specialties to suspect PNG at the beginning of its development. When the diagnosis is delayed, the patient with thrombosis is treated under different diagnoses, time is running out… Identification of patients at risk can affect the outcome of PNG. Highly sensitive flow cytometry makes it possible to detect an APG clone with a size of 0.01% or more. Monoclonal antibody therapy changed the natural course of APG. The article presents the medical history of a patient with PNG. The diagnosis was made in our clinic at the stage of serious thrombotic complications, after a stay in two Moscow clinics where this disease was not suspected.