Paroxysmal Nocturnal Hemoglobinuria Research Articles

A case of allogeneic peripheral blood stem cell in a paroxysmal nocturnal hemoglobinuria patient from a COVID-positive donor: Managing the unpreventable

Abstract: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired disease caused by clonal expansion of one or more hematopoietic stem cell lines due to a somatic mutation of the phosphatidylinositol glycan anchor gene. Peripheral blood stem cell (PBSC) harvest is a high-risk procedure and the major concern was regarding the development of COVID infection in the recipient. Herein, we describe an inevitable case of PBSC harvest in a PNH patient who was already started on myeloablation and where the donor became positive 1 day before the harvest. Considering the risk–benefit ratio and the need for elaborate arrangements, the initial plan for bone marrow harvesting was changed to PBSC, and hence, the harvest was performed in a COVID-designated unit. No features of graft versus host disease (GVHD) were observed in the patient. The patient was examined for signs and symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and there was no evidence of any infection after the procedure. The weekly analysis of the same was done for 1 month after PBSC and the SARS-CoV-2 status remained negative. The authors opine that PBSC from SARS-CoV-2 can be performed safely in some unpreventable situations.

Comparison of human leukocyte antigen in patients with paroxysmal nocturnal hemoglobinuria of different clone sizes.

Glycosylphosphatidylinositol-anchored protein-deficient hematopoietic stem and progenitor cell development caused by PIGA mutations cannot fully explain the pathogenesis of paroxysmal nocturnal hemoglobinuria (PNH). Herein, patients newly diagnosed with PNH at our hospital between April 2019 and April 2021 were recruited. The human leukocyte antigen (HLA) class I and II loci were analyzed, and patients were stratified by PNH clone sizes: small (< 50%) and large (≥ 50%). In 40 patients (29 males; 72.5%), the median PNH clone size was 72%. Thirteen (32.5%) and twenty-seven (67.5%) patients harbored small and large PNH clones, respectively. DRB1*15:01 and DQB1*06:02 had higher frequencies in patients with PNH than in healthy controls (adjusted P-value = 4.10 × 10-4 and 4.10 × 10-4, respectively). Whole HLA class I and II allele contributions differed (P = 0.046 and 0.065, not significant difference) when comparing patients with small and large PNH clones. B*13:01 and C*04:01 allelic frequencies were significantly higher in patients with small clones (P = 0.032 and P = 0.032, respectively). Patients with small clones had higher class II HLA evolutionary divergence (HED) (P = 0.041) and global class I and II HED (P = 0.019). In the entire cohort, 17 HLA aberrations were found in 11 (27.5%) patients. No significant differences in HLA aberrations were found between patients with small or large clones. In conclusion, patients with small clones tended to have a higher frequency of immune attack-associated alleles. A higher HED in patients with small clones may reflect a propensity for T cell-mediated autoimmunity. HLA aberrations were similar between patients with small and large clones.

Complement inhibition in paroxysmal nocturnal hemoglobinuria: From biology to therapy.

Complement inhibitors are the mainstay of paroxysmal nocturnal hemoglobinuria (PNH) treatment. The anti-C5 monoclonal antibody eculizumab was the first treatment to improve hemolysis, thrombotic risk, and survival in PNH although at the price of a life-long intravenous fortnightly drug. Additionally, suboptimal response may occur in up to 2/3 of patients with persistent anemia due to incomplete control of intravascular hemolysis, development of upstream C3-mediated extravascular hemolysis (EVH), or concomitant bone marrow failure. Ravulizumab, a longer half-life anti-C5 developed from eculizumab, administered every 8 weeks, improved patient convenience, and reduced pharmacokinetic breakthrough hemolysis (BTH) by establishing more stable anti-C5 concentrations. More recently, several other anti-C5 compounds (crovalimab, pozelimab, tesidolumab, cemdisiran, zilucoplan, and coversin) are on study in clinical trials. Upstream inhibition of complement cascade was also explored with the anti-C3 pegcetacoplan, and with the alternative pathway inhibitors iptacopan (anti-factor B) and danicopan (anti-factor D). These drugs efficiently target EVH and are able to improve anemia and transfusion need in suboptimal responders to anti-C5. The route and schedule of administration (twice weekly subcutaneously for pegcetacoplan and twice or thrice oral daily dosing for iptacopan and danicopan, respectively) are very convenient but pose novel issues regarding adherence. Additionally, both anti-C5 and upstream inhibitors do not resolve the unmet need of pharmacodynamic BTH events due to complement amplifying conditions such as infections, traumas, and surgery. In this review, we will recapitulate PNH physiopathology, clinical presentation, and diagnosis and describe available and developing drugs that will lead to a precision medicine approach for this rare though heterogenous disease.

Efficacy, Safety and Quality of Life of Pegcetacoplan in Japanese Patients With Paroxysmal Nocturnal Hemoglobinuria Treated Within the Phase 3 PEGASUS Trial.

Pegcetacoplan, the first approved proximal complement C3 inhibitor, showed superiority to eculizumab in improving hemoglobin levels and clinical outcomes in the phase 3 PEGASUS study in patients with paroxysmal nocturnal hemoglobinuria (PNH) and inadequate response to eculizumab. This analysis evaluates the efficacy and safety of pegcetacoplan for Japanese patients in PEGASUS, as they are known for different clinicopathologic features compared to non-Asian patients. Ten Japanese patients were enrolled to receive pegcetacoplan (n=5) or eculizumab (n=5) during the 16-week randomized controlled period. All patients received pegcetacoplan monotherapy during the open-label period until Week 48. Treatment with pegcetacoplan improved hemoglobin with a mean change from baseline of 2.4 g/dL at Week 16, which was sustained through 48 weeks. Pegcetacoplan-treated Japanese patients experienced sustained improvements in key secondary efficacy endpoints, including freedom from transfusion, lactate dehydrogenase level, reticulocyte count, and FACIT-Fatigue score. The safety profile was consistent with previously reported data from pegcetacoplan studies. No events of hemolysis, meningococcal infection, or thrombosis were reported in the Japanese population and all Japanese patients remained on treatment throughout the study. These data suggest that Japanese patients with PNH can be effectively and safely managed with pegcetacoplan. gov identifier: NCT03500549.

Hemolysis events in the Phase 3 PEGASUS study of pegcetacoplan in patients with paroxysmal nocturnal hemoglobinuria

Patients with paroxysmal nocturnal hemoglobinuria (PNH) experience complement-mediated intravascular hemolysis leading to anemia, fatigue, and potentially life-threatening thrombotic complications. Pegcetacoplan, a C3 inhibitor, demonstrated sustained improvements in hematological and clinical parameters in the Phase 3 PEGASUS trial in patients with PNH who remained anemic despite C5 inhibitor therapy. The current post-hoc analysis describes 26 hemolysis adverse events (AEs) experienced in 19 patients during pegcetacoplan therapy in PEGASUS and baseline patient characteristics potentially associated with increased hemolysis risk. Lactate dehydrogenase (LDH) ≥2× the upper limit of normal (ULN) was observed in 19 events, including 2 with LDH ≥10× ULN. All patients experienced decreased hemoglobin during hemolysis (mean decrease: 3.0 g/dL). In 16 events (62%) a potential complement-amplifying condition underlying the event could be identified. Hemolysis AEs led to study discontinuation in 5 patients. However, 17 of 26 (65%) hemolysis AEs were manageable without pegcetacoplan discontinuation. A greater proportion of patients with hemolysis AEs (n=19) had key characteristics of higher disease activity at baseline compared to patients without hemolysis AEs (n=61), namely higher-than-label eculizumab dose (53% vs 23%), detectable CH50 (74% vs 54%) and ≥4 transfusions in the previous 12 months (68% vs 51%). These characteristics may be useful predictors of potential future hemolysis events. ClinicalTrials.gov identifier: NCT03500549

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.

Paroxysmal Nocturnal Hemoglobinuria and Primary Myelofibrosis as an Extremely Rare Combination of Clonal Hematological Diseases: A Literature Review and Two Clinical Case Reports

The combinations of paroxysmal nocturnal hemoglobinuria (PNH) and chronic myeloproliferative neoplasms (CMPNs) are extremely rare. All of them refer to clonal hematological diseases and are characterized by high thrombosis risk, which most commonly causes death. This paper provides literature data on 38 combined cases of PNH and Ph-negative/Ph-positive CMPNs mainly in the “case report” format, taken from 22 sources published in 1970–2022. Additionally, the paper reports personal experience with 2 combined cases of PNH and primary myelofibrosis (PMF/PNH) from the archive of the Moscow Municipal Center for Hematology (SP Botkin City Clinical Hospital).

Cost-Utility Analysis Comparing Pegcetacoplan to Anti-C5 Monoclonal Antibodies in the Treatment of Paroxysmal Nocturnal Hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria is a rare, acquired disease characterized by hemolytic episodes and associated with significant clinical burden. The introduction of C5 inhibitory monoclonal antibodies (C5i) represented a major breakthrough in PNH treatment, effectively reducing intravascular hemolysis (IVH) but showing limited impact on extravascular hemolysis (EVH). In 2021, the C3 inhibitor pegcetacoplan was approved by EMA and recently reimbursed in Italy, which also has the advantages in the reduction of both IVH and EVH, increasing hemoglobin values and simultaneously improving the quality of life and fatigue of patients. A cost-utility analysis was developed to compare pegcetacoplan to C5i (eculizumab and ravulizumab) in the PNH population who remain anemic after treatment with C5i for at least 3 months. The analysis employed a Markov model with a 5-year time horizon whereby patients can transition among 3 PNH health states, adopting the perspective of the Italian NHS. Efficacy data were sourced from the PEGASUS study, with drug prices reflecting ex-factory costs. Additionally, costs associated with resource utilization, adverse events, and complications were estimated based on outpatient and hospital care rates, excluding indirect expenses. Utility and disutility values related to transfusions were also considered, with pegcetacoplan allowing for dose escalation. The cumulative cost of treatment per individual patient at 5 years was estimated to be €1,483,454 for pegcetacoplan, €1,585,763 for eculizumab, and €1,574,826 for ravulizumab. Pegcetacoplan demonstrated a superior increase in quality-adjusted life years (QALYs) compared to both eculizumab (0.51 increase) and ravulizumab (0.27 increase). Furthermore, pegcetacoplan showed a reduction in complication management costs (€22,891 less compared to eculizumab and €22,611 less compared to ravulizumab) and lower transfusion-related expenses (€14,147 less than both C5i treatments). Pegcetacoplan emerged as the dominant strategy in this analysis, being more effective, less expensive and improves quality of life in the analyzed population affected by PNH.

Detection of GPI-deficient Cells in Paroxysmal Nocturnal Hemoglobinuria Patients Using Flow Cytometry: Current Status in Korea and Proposal for Testing Guidelines

Detection of GPI-deficient Cells in Paroxysmal Nocturnal Hemoglobinuria Patients Using Flow Cytometry: Current Status in Korea and Proposal for Testing Guidelines

Paroxysmal nocturnal hemoglobinuria–related thrombosis in the era of novel therapies: a 2043–patient-year analysis

AbstractThrombophilia is 1 of the principal features of paroxysmal nocturnal hemoglobinuria (PNH) and constitutes the main cause of disease morbidity/mortality. Anticomplement treatment has revolutionized the natural history of PNH, with control of the hemolytic process and abolition of thrombotic events (TEs). However, no guidelines exist for the management of thromboembolic complications in this setting, with type and duration of anticoagulation depending on individual practices. Besides, a scarcity of data is present on the efficacy of direct oral anticoagulants (DOACs). Herein, we accrued a large real-world cohort of patients with PNH from 4 US centers to explore features, predictors of TE, and anticoagulation strategies. Among 267 patients followed up for a total of 2043 patient-years, 56 (21%) developed TEs. This occurred at disease onset in 43% of cases, involving more frequently the venous system, typically as Budd-Chiari syndrome. Rate of TEs was halved in patients receiving complement inhibitors (21 vs 40 TEs per 1000 patient-years in untreated cases, with a 2-year cumulative incidence of thrombosis of 3.9% vs 18.3%, respectively), and varied according to PNH granulocytes and erythrocytes clone size, type, disease activity parameters, as well as number (≥2 mutations, or less) and variant allelic frequency of PIGA mutations. Anticoagulation with warfarin (39%), DOACs (37%), and low-molecular weight heparin (16%) was administered for a median of 29 months (9-61.8). No thrombotic recurrence was observed in 19 patients treated with DOACs at a median observation of 17.1 months (8.9-45) whereas 14 cases discontinued anticoagulation without TE recurrence at a median time of 51.4 months (29.9-86.8).

Danicopan: First Approval.

Danicopan (Voydeya®) is an oral complement factor D inhibitor that is being developed by Alexion AstraZeneca Rare Disease as add-on treatment to ravulizumab or eculizumab for patients with clinically significant extravascular haemolysis. Danicopan recently received approval in Japan for the treatment of adults with paroxysmal nocturnal haemoglobinuria (PNH) when used in addition to a complement component 5 (C5) inhibitor. Subsequently, the European Medicines Agency adopted a positive opinion recommending the granting of marketing authorisation for danicopan for the treatment of patients with PNH who continue to have residual haemolytic anaemia despite treatment with a complement C5 inhibitor. This article summarizes the milestones in the development of danicopan leading to this first approval for PNH.

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.

Evaluation of the impact of two C5 genetic variants on C5-eculizumab complex stability at the molecular level

Complement C5 is the target of the monoclonal antibody eculizumab, used in complement dysregulating disorders, like the rare disease Paroxysmal Nocturnal Hemoglobinuria (PNH). PNH is an acquired hematopoietic stem cell condition characterized by aberrant destruction of erythrocytes, chronic hemolytic anemia, and thromboembolism propensity. C5 is a protein component of the complement system which is part of the immune system of the body and plays a prominent role in the destruction of red blood cells, misidentifying them as a threat. This work describes the application of molecular dynamics simulations to the study of the underlying interactions between complement C5 and eculizumab. This study also reveals the importance of single nucleotide polymorphisms on C5 protein concerning the effective inhibition of the mAB, involving the mechanistic events taking place at the interface spots of the complex. The predicted conformational change in the C5 Arg885/His/Cys mutation has implications on the protein’s interaction with eculizumab, compromising their compatibility. The acquired insights into the conformational changes, dynamics, flexibility, and interactions shed light on the knowledge of the function of this biomolecule providing answers about the poor response to the treatment in PNH patient carriers of the mutations. By investigating the intricate dynamics, significant connections between C5 and eculizumab can be uncovered. Such insights may aid in the creation of novel compounds or lead to the enhancement of eculizumab’s efficacy. Communicated by Ramaswamy H. Sarma

Fatigue Item Response among Hemoglobin-Normalized Patients with Paroxysmal Nocturnal Hemoglobinuria: PEGASUS Trial Results at 16 and 48 Weeks.

Background. A common symptom of paroxysmal nocturnal hemoglobinuria (PNH) is fatigue, which in some patients can be severe. Eculizumab (Ecu) has proven efficacy in controlling intravascular hemolysis, but commonly results in persistent anemia and fatigue. Pegcetacoplan's (Peg) efficacy was documented in the PEGASUS phase III clinical trial, showing improved hemoglobin (Hb) and patient-reported fatigue. This post-hoc analysis sought to describe this fatigue improvement related to Hb normalization using the Functional Assessment of Chronic Illness Therapy-Fatigue subscale (FACIT-F)'s individual questions to speak more directly to patients' experience and clinicians' day-to-day practice. Methods. The PEGASUS trial compared Peg with Ecu in patients who remained anemic on Ecu over 16 weeks (n = 41 and 39, for Peg and Ecu, respectively), after which all patients received Peg open label for 32 weeks ("Peg" vs. "Ecu-to-Peg" at Week 48). Hb normalization was defined as ≥12-16 g/dL for females and ≥13.6-18 g/dL for males. The FACIT-F assessed fatigue. Using the complete-case data set, Cohen's d summarized the effect sizes of the mean FACIT-F item change for both study arms from the baseline to week 16 (n = 36 and 37, for Peg and Ecu, respectively) and from the baseline to week 48 (n = 30 and 29, for Peg and Ecu-to-Peg, respectively), and for Hb-normalized patients in each study arm from the baseline to week 16 (n = 14 and 0, for Peg and Ecu, respectively) and from the baseline to week 48 (n = 10 and 12, for Peg and Ecu-to-Peg, respectively). Results. The FACIT-F scores for both arms were worse at the baseline compared to later in the trial. Peg patients reported improvements on all fatigue items at Week 16, but Ecu patients reported improvement in only one item. At Week 48, the improvement in fatigue was maintained in Peg patients, and Ecu-to-Peg patients' fatigue improved on all FACIT-F items. Hb normalization was achieved in 14 Peg patients but no Ecu patients at Week 16, and in 10 Peg and 12 Ecu-to-Peg patients, respectively, at week 48. The FACIT-F single items showing the largest change overall, and particularly in Hb-normalized patients across the study arms, were related to symptoms and social limitations. Conclusions. Peg patients reported lasting improvements in fatigue. Patients who were anemic on Ecu reported sustained improvements in fatigue with Peg treatment. Patients who had Hb normalization generally had large, clinically important improvements in fatigue items.

Oral Iptacopan Monotherapy in Paroxysmal Nocturnal Hemoglobinuria

BackgroundPersistent hemolytic anemia and a lack of oral treatments are challenges for patients with paroxysmal nocturnal hemoglobinuria who have received anti-C5 therapy or have not received complement inhibitors. Iptacopan, a first-in-class oral factor B inhibitor, has been shown to improve hemoglobin levels in these patients.MethodsIn two phase 3 trials, we assessed iptacopan monotherapy over a 24-week period in patients with hemoglobin levels of less than 10 g per deciliter. In the first, anti-C5–treated patients were randomly assigned to switch to iptacopan or to continue anti-C5 therapy. In the second, single-group trial, patients who had not received complement inhibitors and who had lactate dehydrogenase (LDH) levels more than 1.5 times the upper limit of the normal range received iptacopan. The two primary end points in the first trial were an increase in the hemoglobin level of at least 2 g per deciliter from baseline and a hemoglobin level of at least 12 g per deciliter, each without red-cell transfusion; the primary end point for the second trial was an increase in hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion.ResultsIn the first trial, 51 of the 60 patients who received iptacopan had an increase in the hemoglobin level of at least 2 g per deciliter from baseline, and 42 had a hemoglobin level of at least 12 g per deciliter, each without transfusion; none of the 35 anti-C5–treated patients attained the end-point levels. In the second trial, 31 of 33 patients had an increase in the hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion. In the first trial, 59 of the 62 patients who received iptacopan and 14 of the 35 anti-C5–treated patients did not require or receive transfusion; in the second trial, no patients required or received transfusion. Treatment with iptacopan increased hemoglobin levels, reduced fatigue, reduced reticulocyte and bilirubin levels, and resulted in mean LDH levels that were less than 1.5 times the upper limit of the normal range. Headache was the most frequent adverse event with iptacopan.ConclusionsIptacopan treatment improved hematologic and clinical outcomes in anti-C5–treated patients with persistent anemia — in whom iptacopan showed superiority to anti-C5 therapy — and in patients who had not received complement inhibitors. (Funded by Novartis; APPLY-PNH ClinicalTrials.gov number, NCT04558918; APPOINT-PNH ClinicalTrials.gov number, NCT04820530.)

Development of a target concentration intervention to individualize paroxysmal nocturnal hemoglobinuria treatment with pegcetacoplan.

Pegcetacoplan (Aspaveli®/Empaveli™) is a factor C3 inhibitor that is approved for the treatment of paroxysmal nocturnal hemoglobinuria. An individualized dosing strategy might be useful to improve patient-friendliness and cost-effectiveness of this very expensive drug. Therefore, the aim of this study was to develop an individualized treatment regimen for pegcetacoplan based on the pharmacokinetic-pharmacodynamic data of the manufacturer. We conducted a clinical trial simulation with the approved dosing regimen of 1080mg twice-weekly and a target concentration intervention-based dosing regimen in patients with and without prior eculizumab use. For eculizumab-naïve patients, the target concentration intervention-based dosing regimen resulted in a comparable fraction of patients with LDH normalization (LDH < 226 U/L) and hemoglobulin normalization (> 12g/dL) compared to the approved regimen (LDH 50.2% and 50.0% respectively and hemoglobulin 45.6% and 44.4%). A modest dose reduction of ~ 5% was possible with target concentration intervention-based dosing. An intensified dosing interval was necessary in 2.3% of the patients however an interval prolongation was possible in 28.2% of the patients. Similar results were obtained for patients prior treated with eculizumab. In this study we show the potential of an individualized dosing regimen of pegcetacoplan with can improve patient friendliness in approximately 30% of the patients and improve therapy in approximately 2% of the patients at slightly reduced costs.

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.

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

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

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 invitro/exvivo assays using standard classical and alternative pathway restricted hemolysis assays next to hemolysis assays with paroxysmal nocturnal hemoglobinuria erythrocytes. A novel invitro 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.