Paroxysmal nocturnal haemoglobinuria

The cost-effectiveness, of pegcetacoplan compared with ravulizumab for the treatment of paroxysmal nocturnal hemoglobinuria, in a UK setting

Aim: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by hemolytic anemia, bone marrow failure and thrombosis. We evaluated, the cost-effectiveness of pegcetacoplan, a novel proximal C3 inhibitor, versus ravulizumab in patients with PNH and hemoglobin levels <10.5 g/dl despite eculizumab treatment in the UK healthcare and social services setting. Materials & methods: A Markov cohort framework model, based on the data from the pivotal trial of pegcetacoplan (PEGASUS/NCT03500549), evaluated lifetime costs and outcomes. Patients transitioned through 3 PNH hemoglobin level/red blood cell transfusion health states. Results: Pegcetacoplan provides lower lifetime costs/greater quality-adjusted life years (£6,409,166/14.694QALYs, respectively) versus ravulizumab (£6,660,676/12.942QALYs). Conclusion: Pegcetacoplan is associated with enhanced anemia control, greater QALYs and reduced healthcare costs versus ravulizumab in the UK healthcare and social services setting.

Pegcetacoplan in paroxysmal nocturnal hemoglobinuria: A systematic review on efficacy and safety

Introduction

Pegcetacoplan, a pegylated penta-decapeptide, targets complement C3 to control both intravascular and extravascular hemolysis. This systematic review aims to study the efficacy and safety of pegcetacoplan in paroxysmal nocturnal hemoglobinuria (PNH).

Methods

We performed a comprehensive and systematic literature search for all studies on PubMed, Google Scholar, Cochrane Library, and clinicaltrials.gov. The studies were searched using keywords "paroxysmal nocturnal hemoglobinuria" or "PNH," "Pegcetacoplan" or "Empaveli." The primary outcomes included change in hemoglobin level, transfusion independence, absolute reticulocyte count, and lactate dehydrogenase (LDH) level after pegcetacoplan therapy. The safety outcomes included the proportion of deaths and adverse effects.

Results

We included a total of three studies. The total number of patients with PNH was112. 59.83% were female. In the PADDOCK study and study by Hillmen et al., the average increase in hemoglobin was 3.68 g/L and 2.37 g/L, respectively. In the study by de Castro et al., the hemoglobin level increased from below the lower limit of normal and stayed in the normal range (11.1-15.9 g/L). Absolute reticulocyte count and LDH levels decreased in all patients receiving pegcetacoplan. In the study by de Castro et al., LDH level remained stable, and within <1.5× upper limit of normal, whereas in the study by Hillman, the mean change of LDH from baseline was -15 ± 43 U/L. Two of six, seven of 23, and seven of 41 patients reported adverse events in the study by de Castro et al., PADDOCK, and Hillmen et al., respectively.

Conclusion

Pegcetacoplan effectively improves hemoglobin level and transfusion requirements in patients with PNH, including those unresponsive to eculizumab.

COVID-19 associated coagulopathy: Mechanisms and host-directed treatment

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is associated with specific coagulopathy that frequently occurs during the different phases of coronavirus disease 2019 (COVID-19) and can result in thrombotic complications and/or death. This COVID-19-associated coagulopathy (CAC) exhibits some of the features associated with thrombotic microangiopathy, particularly complement-mediated hemolytic-uremic syndrome. In some cases, due to the anti-phospholipid antibodies, CAC resembles catastrophic anti-phospholipid syndrome. In other patients, it exhibits features of hemophagocytic syndrome. CAC is mainly identified by: increases in fibrinogen, D-dimers, and von Willebrand factor (released from activated endothelial cells), consumption of a disintegrin and metalloproteinase with thrombospondin type 1 motifs, member 13 (ADAMTS13), over activated and dysregulated complement, and elevated plasma cytokine levels. CAC manifests as both major cardiovascular and/or cerebrovascular events and dysfunctional microcirculation, which leads to multiple organ damage. It is not clear whether the mainstay of COVID-19 is complement overactivation, cytokine/chemokine activation, or a combination of these activities. Available data have suggested that non-critically ill hospitalized patients should be administered full-dose heparin. In critically ill, full dose heparin treatment is discouraged due to higher mortality rate. In addition to anti-coagulation, four different host-directed therapeutic pathways have recently emerged that influence CAC: (1) Anti-von Willebrand factor monoclonal antibodies; (2) activated complement C5a inhibitors; (3) recombinant ADAMTS13; and (4) Interleukin (IL)-1 and IL-6 antibodies. Moreover, neutralizing monoclonal antibodies against the virus surface protein have been tested. However, the role of antiplatelet treatment remains unclear for patients with COVID-19.

The importance of terminal complement inhibition in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, chronic hematologic disorder associated with inappropriate terminal complement activity on blood cells that can result in intravascular hemolysis (IVH), thromboembolic events (TEs), and organ damage. Untreated individuals with PNH have an increased risk of morbidity and mortality. Patients with PNH experiencing IVH often present with an elevated lactate dehydrogenase (LDH; ⩾ 1.5 × the upper limit of normal) level which is associated with a significantly higher risk of TEs, one of the leading causes of death in PNH. LDH is therefore used as a biomarker for IVH in PNH. The main objective of PNH treatment should therefore be prevention of morbidity and mortality due to terminal complement activation, with the aim of improving patient outcomes. Approval of the first terminal complement inhibitor, eculizumab, greatly changed the treatment landscape of PNH by giving patients an effective therapy and demonstrated the critical role of terminal complement and the possibility of modulating it therapeutically. The current mainstays of treatment for PNH are the terminal complement component 5 (C5) inhibitors, eculizumab and ravulizumab, which have shown efficacy in controlling terminal complement-mediated IVH, reducing TEs and organ damage, and improving health-related quality of life in patients with PNH since their approval by the United States Food and Drug Administration in 2007 and 2018, respectively. Moreover, the use of eculizumab has been shown to reduce mortality due to PNH. More recently, interest has arisen in developing additional complement inhibitors with different modes of administration and therapeutics targeting other components of the complement cascade. This review focuses on the pathophysiology of clinical complications in PNH and explores why sustained inhibition of terminal complement activity through the use of complement inhibitors is essential for the management of patients with this chronic and debilitating disease.

A Splice Site Mutation Associated with Congenital CD59 Deficiency

Congenital CD59 deficiency is a recently described rare autosomal recessive disease associated with CD59 gene mutations that lead to deficient or dysfunctional CD59 protein on the cell surface. The disease is characterized by the early onset of chronic hemolysis, relapsing peripheral demyelinating neuropathy, and recurrent ischemic strokes. To date, there are 14 patients with 4 exon mutations reported globally. A young boy with early onset peripheral neuropathy and atypical hemolytic uremic syndrome is presented. Next-generation sequencing (NGS) identified a homozygous splice site variant in intron 1 of the CD59 gene (c.67 + 1G > T). This variant alters a consensus donor splicing site. Quantitative reverse transcription PCR showed that CD59 mRNA expression in the patient is significantly reduced to 0.017-fold compared to the controls. Flow cytometry showed the lack of CD59 protein on the surface of the patient’s red blood cells. This variant is the first splice site mutation reported to be associated with congenital CD59 deficiency.

Iptacopan monotherapy in patients with paroxysmal nocturnal hemoglobinuria: a 2-cohort open-label proof-of-concept study

Iptacopan (LNP023) is a novel, oral selective inhibitor of complement factor B under clinical development for paroxysmal nocturnal hemoglobinuria (PNH). In this ongoing open-label phase 2 study, PNH patients with active hemolysis were randomized to receive single-agent iptacopan twice-daily, at a dose of either 25 mg for 4 weeks followed by 100 mg for up to 2 years (cohort 1) or 50 mg for 4 weeks followed by 200 mg for up to 2 years (cohort 2). At the time of interim analysis, of 13 PNH patients enrolled, all 12 evaluable for efficacy achieved the primary endpoint of reduction in serum lactate dehydrogenase (LDH) levels by at least 60% by week 12 as compared to baseline; mean LDH levels dropped rapidly and durably, namely by 77% and 85% at week 2 and by 86% and 86% at week 12 in cohorts 1 and 2, respectively. Most patients achieved a clinically meaningful improvement in hemoglobin levels and all but one patient remained transfusion-free up to week 12. Other markers of hemolysis, including bilirubin, reticulocytes and haptoglobin, showed consistent improvements. No thromboembolic events were reported, and iptacopan was well tolerated, with no severe or serious adverse events reported up until the data cutoff. In addition to the previously reported beneficial effect of iptacopan add-on therapy to eculizumab, this study showed that iptacopan monotherapy in treatment-naïve PNH patients resulted in normalization of hemolytic markers and rapid transfusion-free improvement of hemoglobin levels in most patients. Registered at www.clinicaltrials.gov as NCT03896152.

Evaluating ravulizumab for the treatment of children and adolescents with paroxysmal nocturnal hemoglobinuria

INTRODUCTION

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal stem cell disease harvesting a somatic mutation in the phosphatidylinositol glycan class A (PIG-A) gene. This mutation results in a deficiency in cell membrane complement regulators leading to activation of the terminal complement pathway, clinically presenting as hemolytic anemia and thrombosis, and frequently associated with bone marrow failure. This condition was historically managed with supportive care and bone marrow transplant.

AREAS COVERED

This paper will review primary data on the pharmacology, efficacy, and safety of ravulizumab in the pediatric/adolescent population gathered from literature search from PubMed, abstracts from annual meetings, and medication package inserts. Eligible clinical trials identified on the clinicaltrials.gov website are also briefly discussed.

EXPERT OPINION

: The discovery of eculizumab, a monoclonal antibody against complement protein 5, has revolutionized the PNH landscape, with decreased hemolysis and risk of thrombosis, improved quality-of-life, and has become the standard of care. Ravulizumab, a longer-acting C5-inhibitor with 4 times the half-life of eculizumab, was recently approved for pediatric patients with PNH. Ravulizumab is effective, safe, and has the potential to improve quality of life further. In addition, ongoing clinical trials using second-generation complement inhibitors may provide promising new interventions in PNH.

Paroxysmal nocturnal haemoglobinuria, diagnosis and haematological findings, first report from Iran, model for developing countries

Since paroxysmal nocturnal haemoglobinuria (PNH) was first described in 1881, the diagnosis and follow-up patients diagnosed with the illness has remained an area of concern, with several different techniques of varying sensitivity having been described in the literature for both the diagnosis and monitoring treatment of the disease. PNH is a rare and life-threatening disease that manifests symptoms of haemolytic anaemia. Hence, a quick and reliable technique for precise diagnosis would be crucial. PNH patients who have previously been diagnosed with aplastic anaemia or myelodysplastic syndrome carry small PNH clones and for more than a century traditional method with low sensitivity was used for such patients. In 2010, the International Clinical Cytometry Society described a highly sensitive method for detection and quantification of different types of PNH clones using multi-colour flow cytometry. In this method, a three-colour flow cytometer is essential to detect PNH affected cells amongst monocytes and granulocytes. This started a new era in the diagnosis of patients who carry small clones of PNH cells. Before this, flow cytometric analysis was used only for detection of PNH cells amongst erythrocytes. By using flow cytometry instruments with more light sources, the sensitivity of detection and quantification of PNH clones would be augmented. However, standardisation and crosstalk compensation would be the most concerning issue. For the first time in Iran, we set up and standardised multi-colour flow cytometry technique to detect PNH cells in erythrocytes and leukocytes at Payvand medical laboratory.

Literature Review of Fatigue Scales and Association with Clinically Meaningful Improvements in Outcomes Among Patients With and Without Paroxysmal Nocturnal Hemoglobinuria

Introduction

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by anemia and debilitating fatigue. Limited evidence characterizes the association between hemoglobin, an indicator of anemia and disease activity, and patient-reported fatigue scales. This review identifies benchmarks for clinically meaningful improvements in patients with and without PNH.

Methods

MEDLINE, Embase, Cochrane, and PsycINFO databases were searched along with Google Scholar to identify publications for patients with and without PNH. Full-text articles and conference abstracts of clinical trials or observational studies that examined patient-reported fatigue or associations between fatigue and hemoglobin were included.

Results

Fourteen publications were included in this study. Four clinical trials conducted in patients with PNH reported that patients achieved and sustained clinically meaningful improvements in fatigue. However, these studies did not examine the association between fatigue and hemoglobin. Ten studies conducted in patients with cancer and anemia (with or without chemotherapy) demonstrated an association between increased hemoglobin and improvements in fatigue (P < 0.05). The greatest incremental gain in fatigue improvement was observed when hemoglobin increased from 11 to 12 g/dL.

Conclusion

Evidence among patients with cancer without PNH demonstrates that increased hemoglobin levels are associated with clinically significant improvements in fatigue. Future studies should validate this relationship among patients with PNH.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02111-7.

Real-World Eculizumab Dosing Patterns Among Patients with Paroxysmal Nocturnal Hemoglobinuria in a US Population

Purpose

Current pharmacologic management of paroxysmal nocturnal hemoglobinuria (PNH) consists of C5 inhibitors, eculizumab and ravulizumab; however, because patients experience incomplete symptom control, off-label doses may be utilized. We conducted a retrospective, longitudinal cohort study of provider-based claims data to assess the real-world eculizumab dosing patterns in PNH patients.

Patients and Methods

Patients were ≥12 years, received ≥2 eculizumab infusions between January 1, 2015 and September 30, 2019, and had ≥3 months of continuous clinical activity prior to index. The index date was the first claim for eculizumab. Patients with ≥1 diagnosis of another indication for eculizumab were excluded. Treatment patterns including the proportion with high, label-recommended, and low dosages during induction (first 28 days) and maintenance (beginning day 29) phases were described. The proportion and time-to-first dose escalation, defined as an increase in dose or frequency of infusion, were assessed among a subset of patients (ie, escalation analysis cohort).

Results

A total of 707 patients were examined. Mean (standard deviation [SD]) starting dose was 862mg (412mg) and was higher than label-recommended 600mg for 64% of the patients. Mean (SD) dose per infusion was 859mg (391mg) during the induction phase; average dose was higher than label-recommended 600mg for 68%. Mean (SD) dose per infusion during the maintenance phase was 1005mg (335mg); average dose was higher than label-recommended 900mg for 43%. Dose escalation occurred in 40/121 escalation analysis cohort patients. Median time-to-first dose escalation was ~12 months.

Conclusion

Results suggest that deviations from label-recommended dosing patterns were common. Future budget impact assessments of eculizumab should account for real-world dosing patterns to comprehensively assess costs and benefits.

Antigens and Antibodies of the Antiphospholipid Syndrome as New Allies in the Pathogenesis of COVID-19 Coagulopathy

High prevalence of both criteria and extra-criteria antiphospholipid antibodies (aPL) has been reported in COVID-19 patients. However, the differences in aPL prevalence decreased when an age-matched control group was included. The association of aPL with thrombotic events in COVID-19 is very heterogeneous. This could be influenced by the fact that most of the studies carried out were conducted on small populations enriched with elderly patients in which aPL was measured only at a single point and they were performed with non-standardized assays. The few studies that confirmed aPL in a second measurement showed that aPL levels hardly changed, with the exception of the lupus anticoagulant that commonly reduced. COVID-19 coagulopathy is an aPL-independent phenomenon closely associated with the onset of the disease. Thrombosis occurs later in patients with aPL presence, which is likely an additional prothrombotic factor. B2-glycoprotein deficiency (mainly aPL antigen caused both by low production and consumption) is very common during the SARS-CoV2 infection and has been associated with a greater predisposition to COVID-19 complications. This could be a new prothrombotic mechanism that may be caused by the blockage of its physiological functions, the anticoagulant state being the most important.

Novel targeted C3 inhibitor pegcetacoplan for paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, life-threatening acquired blood disease characterized by chronic complement-mediated hemolysis and thrombosis. On May 14, 2021, the US FDA approved a new targeted C3 therapy Empaveli (pegcetacoplan), once called APL-2, for use in adult PNH. This review aims to review the pharmacological properties, clinical safety and efficacy of pegcetacoplan, and provides comprehensive drug information about pegcetacoplan. Pegcetacoplan is a pegylated peptide that targets the proximal complement protein C3. Pegcetacoplan plays a role in the complement cascade that controls C3b-mediated extravascular hemolysis and terminal complement-mediated intravascular hemolysis. Early pharmacokinetic and pharmacodynamic trials proved that pegcetacoplan had good tolerability and acceptable safety, while reducing complement activity. The pivotal phase III trial PEGASUS of PNH patients with a suboptimal response to eculizumab reported that pegcetacoplan improved hemoglobin levels better than eculizumab (p < 0.001). Compared with eculizumab, patients who received pegcetacoplan had a higher chance of not requiring a blood transfusion within 16 weeks (85% vs. 15%, p < 0.001). The safety of pegcetacoplan was similar to that of eculizumab. Adverse events such as injection site reactions and diarrhea occurred frequently following pegcetacoplan administration. The prescription recommended dosage is 1080 mg, subcutaneously infusion twice a week.

Pegcetacoplan for Paroxysmal Nocturnal Hemoglobinuria

Approximately a third of patients with paroxysmal nocturnal hemoglobinuria (PNH) remain transfusion dependent or have symptomatic anemia despite treatment with a C5 inhibitor. Pegcetacoplan inhibits complement proximally at the level of C3 and is highly effective in treating persistent anemia resulting from C3-mediated extravascular hemolysis. We describe the rationale for C3 inhibition in the treatment of PNH and discuss preclinical and clinical studies using pegcetacoplan and other compstatin derivatives. We propose an approach for sequencing complement inhibitors in PNH.

Persistent Large Granular Lymphocyte Clonal Expansions: “The Root of Many Evils”—And of Some Goodness

Simple Summary

Large granular lymphocyte leukemia (LGLL) is a chronic disorder of either mature T or NK lymphocytes. As clonal expansions of the immune system cells, difficulties in the distinction between a true neoplasia and a physiological reactive process have been common since its description. We review here the different conditions associated with persistent clonal LGL expansions and discuss their potential origin and whether they can modulate the clinical features.

Abstract

Large granular lymphocyte leukemia (LGLL) is a chronic disease of either mature phenotype cytotoxic CD3+ T lymphocytes or CD3- NK cells. LGLL diagnosis is hampered by the fact that reactive persistent clonal LGL expansions may fulfill the current criteria for LGLL diagnoses. In addition to the presence of characteristic clinical and hematological signs such as anemia or neutropenia, LGLL/LGL clonal expansions have been associated with an array of conditions/disorders. We review here the presence of these persistent clonal expansions in autoimmune, hematological disorders and solid neoplasms and after hematopoietic stem cell transplantation. These associations are a unique translational research framework to discern whether these persistently expanded LGL clones are causes or consequences of the concomitant clinical settings and, more importantly, when they should be targeted.

Pregnancy outcomes in women receiving eculizumab for the management of paroxysmal nocturnal haemoglobinuria

Aims

To report pregnancy outcomes and complications in women receiving eculizumab for the management of paroxysmal nocturnal haemoglobinuria.

Methods

A service evaluation of routinely collected medical records across 49 pregnancies in 21 women.

Results

Eculizumab was used in 37 pregnancies, 31 of which (83.8%) ended in live birth. Eight infants (25.8%) were born prematurely. Over half (54%) of women required increases in their dose of eculizumab to control their haemolysis. There were no reported cases of maternal thrombosis. Major ante/postpartum bleeding necessitating urgent intervention was reported in 10.8% of pregnancies. There were two cases of intrauterine death and three miscarriages. There were no maternal or neonatal deaths. Three newborns required prolonged hospital stays.

Conclusions

Eculizumab appears to benefit pregnant women with paroxysmal nocturnal haemoglobinuria and pregnancy outcomes following its use are largely good.

Frequencies of glycosylphosphatidylinositol (GPI)-deficient cells using high-sensitivity flow cytometry as per the 2018 ICCS/ESCCA consensus guideline in patients with hematologic malignancy, aplastic anemia, or cytopenia

OBJECTIVES

We examined the frequencies and sizes of glycosylphosphatidylinositol(GPI)-deficient cells as per the International Clinical Cytometry Society/European Society for Clinical Cell Analysis(ICCS/ESCCA) consensus guidelines for the high-sensitivity detection of GPI-deficient cells.

METHODS

In 2018, the ICCS/ESCCA guidelines for the high-sensitivity detection of GPI-deficient cells were published. We evaluated frequencies and sizes of GPI-deficient red blood cells(RBCs), neutrophils, and monocytes as determined using the ICCS/ESCCA guidelines and Clinical and Laboratory Standards Institute(CLSI) guidelines in patients with a hematologic malignancy, aplastic anemia, or cytopenia.

RESULTS

A total of 106(38.7%) patients exhibited GPI deficiency in at least one blood cell lineage. GPI-deficient cells of one or more lineages were found in 62.7% of patients with a hematologic malignancy, 51.1% of patients with aplastic anemia, and 23.4% of patients with cytopenia. GPI-deficient monocytes were most frequently detected in all three groups. By population size, GPI-deficient clones (>1%) in monocytes were mostly detected in patients with a hematologic malignancy or aplastic anemia. Rare cells with GPI deficiency(<0.1%) in monocytes were most common among patients with cytopenia.

CONCLUSION

High-sensitive flow cytometry analysis including monocytes may be necessary for patients with a hematologic disorder.

The state of complement in COVID-19

Hyperactivation of the complement and coagulation systems is recognized as part of the clinical syndrome of COVID-19. Here we review systemic complement activation and local complement activation in response to the causative virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and their currently known relationships to hyperinflammation and thrombosis. We also provide an update on early clinical findings and emerging clinical trial evidence that suggest potential therapeutic benefit of complement inhibition in severe COVID-19.

Clinical observation of low-dose combination chemotherapy in refractory/recurrent paroxysmal nocturnal hemoglobinuria patients: A single-center retrospective analysis

BACKGROUND

We performed a retrospective analysis to investigate the clinical characteristics and therapeutic strategies of 20 refractory/recurrent PNH patients, including the clinical efficacy of chemotherapy treatment, safety, and survival.

METHODS

The clinical data of 20 classic PNH patients who were refractory/recurrent or had glucocorticoid dependence in our hospital were analyzed, including clinical manifestations, laboratory examinations, treatment efficacy, and survival.

RESULTS

Seventeen patients had a marked improvement in anemia after chemotherapy, 14 patients acquired blood transfusion independence, and the Hb of 3 patients increased to normal levels. Although 6 patients still needed blood transfusion, the transfusion interval was significantly prolonged. The percentages of LDH, TBIL, and RET, which are indicators of hemolysis, were significantly lower than those before chemotherapy. The dosage of adrenal glucocorticoids was reduced by more than half compared with that before chemotherapy.

CONCLUSIONS

Chemotherapy can reduce PNH clones, promote normal hematopoiesis, and control hemolytic attack. It is a promising and widely used therapeutic method.

Treating Rare Diseases in Africa: The Drugs Exist but the Need Is Unmet

Rare diseases (RD) pose serious challenges in terms of both diagnosis and treatment. Legislation was passed in the US (1983) and in EU (2000) aimed to reverse the previous neglect of RD, by providing incentives for development of “orphan drugs” (OD) for their management. Here we analyse the current situation in Africa with respect to (1) sickle cell disease (SCD), that qualifies as rare in the US and in EU, but is not at all rare in African countries (frequencies up to 1–2%); (2) paroxysmal nocturnal haemoglobinuria (PNH), that is ultra-rare in Africa as everywhere else (estimated <10 per million). SCD can be cured by bone marrow transplantation and recently by gene therapy, but very few African patients have access to these expensive procedures; on the other hand, the disease-ameliorating agent hydroxyurea is not expensive, but still the majority of patients in Africa are not receiving it. For PNH, currently most patients In high income countries are treated with a highly effective OD that costs about $400,000 per year per patient: this is not available in Africa. Thus, the impact of OD legislation has been practically nil in this continent. As members of the medical profession and of the human family, we must aim to remove barriers that are essentially financial: especially since countries with rich economies share a history of having exploited African countries. We call on the Global Fund to supply hydroxyurea for all SCD patients; and we call on companies who produce ODs to donate, for every patient who receives an expensive OD in a high income country, enough of the same drug, at a symbolic price, to treat one patient in Africa.

Insights Into the Emergence of Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal Nocturnal Hemoglobinuria (PNH) is a disease as simple as it is complex. PNH patients develop somatic loss-of-function mutations in phosphatidylinositol N-acetylglucosaminyltransferase subunit A gene (PIGA), required for the biosynthesis of glycosylphosphatidylinositol (GPI) anchors. Ubiquitous in eukaryotes, GPI anchors are a group of conserved glycolipid molecules responsible for attaching nearly 150 distinct proteins to the surface of cell membranes. The loss of two GPI-anchored surface proteins, CD55 and CD59, from red blood cells causes unregulated complement activation and hemolysis in classical PNH disease. In PNH patients, PIGA-mutant, GPI (-) hematopoietic cells clonally expand to make up a large portion of patients’ blood production, yet mechanisms leading to clonal expansion of GPI (-) cells remain enigmatic. Historical models of PNH in mice and the more recent PNH model in rhesus macaques showed that GPI (-) cells reconstitute near-normal hematopoiesis but have no intrinsic growth advantage and do not clonally expand over time. Landmark studies identified several potential mechanisms which can promote PNH clonal expansion. However, to what extent these contribute to PNH cell selection in patients continues to be a matter of active debate. Recent advancements in disease models and immunologic technologies, together with the growing understanding of autoimmune marrow failure, offer new opportunities to evaluate the mechanisms of clonal expansion in PNH. Here, we critically review published data on PNH cell biology and clonal expansion and highlight limitations and opportunities to further our understanding of the emergence of PNH clones.

A Pig-a conditional knock-out mice model mediated by Vav-iCre: stable GPI-deficient and mild hemolysis

Paroxysmal nocturnal hemoglobinuria is a clonal disease caused by PIG-A mutation of hematopoietic stem cells. At present, there is no suitable PNH animal model for basic research, therefore, it is urgent to establish a stable animal model. We constructed a Pig-a conditional knock-out mice model by ES targeting technique and Vav-iCre. The expressions of GPI and GPI-AP were almost completely absent in CKO homozygote mice, and the proportion of the deficiency remained stable from birth. In CKO heterozygote mice, the proportion of the deficiency of GPI and GPI-AP was partially absent and decreased gradually from birth until it reached a stable level at 3 months after birth and remained there for life. Compared with normal C57BL/6N mice and Flox mice, pancytopenia was found in CKO homozygous mice, and leukopenia and anemia were found in CKO heterozygotes mice. Meanwhile, in CKO mice, the serum LDH, TBIL, IBIL, complement C5b-9 levels were increased, and the concentration of plasma FHb was increased. Hemosiderin granulosa cells can be seen more easily in the spleens of CKO mice. What's more, CKO mice had stable transcription characteristics. In conclusion, our mouse model has stable GPI-deficient and mild hemolysis, which may be an ideal in vivo experimental model for PNH.

Successful management of unstable angina in a ravulizumab-treated patient with paroxysmal nocturnal hemoglobinuria

Ravulizumab is an anti-C5 antibody approved for treating paroxysmal nocturnal hemoglobinuria (PNH). In August 2019, a 77-year-old Japanese man with PNH, who had been on ravulizumab treatment for 2 years, was hospitalized for chest discomfort and malaise. Electrocardiography identified a right bundle block, and elevated serum troponin I and d-dimer suggested ischemic heart disease. Cardiac catheterization revealed severe stenosis in the left anterior descending coronary artery, and intracoronary stenting relieved his chest discomfort. The final diagnosis was unstable angina unrelated to ravulizumab, and the patient's ravulizumab treatment was uninterrupted with no significant complications of PNH. This case report highlights the importance of continuing complement inhibition therapy during acute coronary events.

基于精氨酸酶切的蛋白质C端肽段富集方法的优化及评估

基于聚合物的蛋白质C端反向富集策略是用于研究蛋白质C端最为广泛的策略之一。目前,基于胰蛋白酶(trypsin)切割精氨酸残基C端(ArgC型酶切)的蛋白C端组学方法对蛋白质C端的鉴定深度仍有待提高。为解决这一问题,该研究对此方法进行了优化和评估:建立了基于“V型”过滤装置的“一锅法”富集流程,避免了副反应的干扰,缩短了样本的制备时间;优化了蛋白水平乙酰化反应条件,最大限度地降低了丝氨酸、苏氨酸、酪氨酸残基上的副反应,提高了肽段鉴定的可信性;优化了基于固相萃取枪头膜片过滤柱(StageTip柱)的样品分离过程,使C端肽段的鉴定深度增加至原来的4倍。通过以上优化,按照肽段水平错误发现率(FDR)<0.01、离子分数(ion score)≥20,且C端带有乙醇胺修饰的数据筛选标准,从人HEK 293T细胞中共鉴定出696个蛋白质C端。若仅要求肽段水平FDR<0.01,鉴定数目进一步增加到933个,这是基于聚合物富集策略的蛋白质C端组学方法所得的最大数据集之一。探索了胰蛋白酶镜像酶(LysargiNase)切割精氨酸残基N端(ArgN型酶切)与不同肽段N端衍生化修饰组合对蛋白质C端鉴定数目和种类的影响,“LysargiNase酶切+肽段N端乙酰化”新策略在原有“胰蛋白酶酶切+肽段N端二甲基化”策略的基础上将鉴定蛋白质C端的种类提升了47%。综上,该研究通过对基于Arg型酶切的蛋白C端组学方法的优化,提升了C端肽段的鉴定深度,扩大了C端肽段鉴定的覆盖范围。该方法将有望成为系统性表征蛋白质C端的有力工具。

When does a PNH clone have clinical significance?

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired blood disease caused by somatic mutations in the phosphatidylinositol glycan class A (PIGA) gene required to produce glycophosphatidyl inositol (GPI) anchors. Although PNH cells are readily identified by flow cytometry due to their deficiency of GPI-anchored proteins, the assessment of the clinical significance of a PNH clone is more nuanced. The interpretation of results requires an understanding of PNH pathogenesis and its relationship to immune-mediated bone marrow failure. Only about one-third of patients with PNH clones have classical PNH disease with overt hemolysis, its associated symptoms, and the highly prothrombotic state characteristic of PNH. Patients with classical PNH benefit the most from complement inhibitors. In contrast, two-thirds of PNH clones occur in patients whose clinical presentation is that of bone marrow failure with few, if any, PNH-related symptoms. The clinical presentations are closely associated with PNH clone size. Although exceptions occur, bone marrow failure patients usually have smaller, subclinical PNH clones. This review addresses the common scenarios that arise in evaluating the clinical significance of PNH clones and provides practical guidelines for approaching a patient with a positive PNH result.

Heme stimulates platelet mitochondrial oxidant production to induce targeted granule secretion

Hemolysis, a pathological component of many diseases, is associated with thrombosis and vascular dysfunction. Hemolytic products, including cell-free hemoglobin and free heme directly activate platelets. However, the effect of hemolysis on platelet degranulation, a central process in not only thrombosis, but also inflammatory and mitogenic signaling, remains less clear. Our group showed that hemoglobin-induced platelet activation involved the production of mitochondrial reactive oxygen species (mtROS). However, the molecular mechanism by which extracellular hemolysis induces platelet mtROS production, and whether these mtROS regulate platelet degranulation remains unknown. Here, we demonstrate using isolated human platelets that cell free heme is a more potent agonist for platelet activation than hemoglobin, and stimulates the release of a specific set of molecules, including the glycoprotein thrombospondin-1 (TSP-1), from the α-granule of platelets. We uncover the mechanism of heme-mediated platelet mtROS production which is dependent on the activation of platelet toll-like receptor 4 (TLR4) signaling and leads to the downstream phosphorylation and inhibition of complex-V by the serine kinase Akt. Notably, inhibition of platelet TLR4 or Akt, or scavenging of mtROS prevents heme-induced granule release in vitro. Further, heme-dependent granule release is significantly attenuated in vivo in mice lacking TLR4 or those treated with the mtROS scavenger MitoTEMPO. These data elucidate a novel mechanism of TLR4-mediated mitochondrial regulation, establish the mechanistic link between hemolysis and platelet degranulation, and begin to define the heme and mtROS-dependent platelet secretome. These data have implications for hemolysis-induced thrombo-inflammatory signaling and for the consideration of platelet mitochondria as a therapeutic target in hemolytic disorders.

Rescue of Glycosylphosphatidylinositol-Anchored Protein Biosynthesis Using Synthetic Glycosylphosphatidylinositol Oligosaccharides

The attachment of proteins to the cell membrane using a glycosylphosphatidylinositol (GPI) anchor is a ubiquitous process in eukaryotic cells. Deficiencies in the biosynthesis of GPIs and the concomitant production of GPI-anchored proteins lead to a series of rare and complicated disorders associated with inherited GPI deficiencies (IGDs) in humans. Currently, there is no treatment for patients suffering from IGDs. Here, we report the design, synthesis, and use of GPI fragments to rescue the biosynthesis of GPI-anchored proteins (GPI-APs) caused by mutation in genes involved in the assembly of GPI-glycolipids in cells. We demonstrated that the synthetic fragments GlcNAc-PI (1), Man-GlcN-PI (5), and GlcN-PI with two (3) and three lipid chains (4) rescue the deletion of the GPI biosynthesis in cells devoid of the PIGA, PIGL, and PIGW genes in vitro. The compounds allowed for concentration-dependent recovery of GPI biosynthesis and were highly active on the cytoplasmic face of the endoplasmic reticulum membrane. These synthetic molecules are leads for the development of treatments for IGDs and tools to study GPI-AP biosynthesis.

Phase 2 study of danicopan in patients with paroxysmal nocturnal hemoglobinuria with an inadequate response to eculizumab

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by uncontrolled terminal complement activation and subsequent intravascular hemolysis (IVH). C5 inhibitors prevent membrane attack complex formation, but patients may experience extravascular hemolysis (EVH) and continue to require blood transfusions. Danicopan, an oral proximal complement inhibitor of alternative pathway factor D (FD), is designed to control IVH and EVH. In a phase 2 dose-finding trial, eculizumab-treated transfusion-dependent patients with PNH (n = 12) received danicopan, 100 to 200 mg thrice daily, in addition to their eculizumab regimen for 24 weeks. End points included hemoglobin (Hgb) change vs baseline at week 24 (primary), reduction in blood transfusions, and patient-reported outcomes. Safety, tolerability, and pharmacokinetics/pharmacodynamics were measured. Twelve patients received ≥1 danicopan dose; 1 patients discontinued from a serious adverse event deemed unlikely related to danicopan. Eleven patients completed the 24-week treatment period. Addition of danicopan resulted in a mean Hgb increase of 2.4 g/dL at week 24. In the 24 weeks prior to danicopan, 10 patients received 31 transfusions (50 units) compared with 1 transfusion (2 units) in 1 patient during the 24-week treatment period. Mean Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue score increased by 11 points from baseline to week 24. The most common adverse events were headache, cough, and nasopharyngitis. Addition of danicopan, a first-in-class FD inhibitor, led to a meaningful improvement in Hgb and reduced transfusion requirements in patients with PNH who were transfusion-dependent on eculizumab. These benefits were associated with improvement of FACIT-Fatigue. This trial was registered at www.clinicaltrials.gov as #NCT03472885.

Tipping the balance: intricate roles of the complement system in disease and therapy

The ability of the complement system to rapidly and broadly react to microbial intruders, apoptotic cells and other threats by inducing forceful elimination responses is indispensable for its role as host defense and surveillance system. However, the danger sensing versatility of complement may come at a steep price for patients suffering from various immune, inflammatory, age-related, or biomaterial-induced conditions. Misguided recognition of cell debris or transplants, excessive activation by microbial or damaged host cells, autoimmune events, and dysregulation of the complement response may all induce effector functions that damage rather than protect host tissue. Although complement has long been associated with disease, the prevalence, impact and complexity of complement’s involvement in pathological processes is only now becoming fully recognized. While complement rarely constitutes the sole driver of disease, it acts as initiator, contributor, and/or exacerbator in numerous disorders. Identifying the factors that tip complement’s balance from protective to damaging effects in a particular disease continues to prove challenging. Fortunately, however, molecular insight into complement functions, improved disease models, and growing clinical experience has led to a greatly improved understanding of complement’s pathological side. The identification of novel complement-mediated indications and the clinical availability of the first therapeutic complement inhibitors has also sparked a renewed interest in developing complement-targeted drugs, which meanwhile led to new approvals and promising candidates in late-stage evaluation. More than a century after its description, complement now has truly reached the clinic and the recent developments hold great promise for diagnosis and therapy alike.

Case Report: Oral Cimetidine Administration Causes Drug-Induced Immune Hemolytic Anemia by Eliciting the Production of Cimetidine-Dependent Antibodies and Drug-Independent Non-specific Antibodies

Previously, it was reported that multiple patients had hemolytic anemia associated with cimetidine administration, while only one patient who had received intravenous cimetidine was serologically diagnosed with drug-induced immune hemolytic anemia (DIIHA) caused by cimetidine-dependent antibodies. However, the ability of oral cimetidine intake to induce the production of antibodies has not been examined. In this study, we report a 44-year-old male patient in whom oral cimetidine administration resulted in cimetidine-dependent antibodies and drug-independent non-specific antibodies, leading to the development of DIIHA. Serological tests showed that the results of direct antiglobulin test (DAT) for anti-IgG (3+) and anti-C3d (1+) were positive. The IgM and IgG cimetidine-dependent antibodies (the highest total titer reached 4,096) were detected in the plasma incubated with O-type RBCs and 1 mg/mL cimetidine or the plasma incubated with cimetidine-coated RBCs. IgG-type drug-independent non-specific antibodies were detected in blood samples collected at days 13, 34, 41, and 82 post-drug intake. This is the first study to report that oral administration of cimetidine can elicit the production of cimetidine-dependent antibodies, leading to DIIHA, and the production of drug-independent non-specific antibodies, resulting in hemolytic anemia independent of cimetidine. Presence of pathogenic antibodies were detectable longer than 41 days. This suggests that patients with DIIHA caused by cimetidine need to be given necessary medical monitoring within 41 days after cimetidine intake.

Thromboembolic complications in autoimmune hemolytic anemia: Retrospective study

Introduction

A small number of retrospective studies suggest AIHA to be associated with an increased risk to suffer from thromboembolic events. However, based on these studies it remains unclear whether the complement activation per is a risk factor to develop thromboembolic events in AIHA patients. The aim of this retrospective study is to investigate the incidence of thromboembolic events and the relation to complement activation in a cohort of AIHA patients.

Patients and Methods

We included 77 patients in this study with a positive DAT and hemolytic parameters or with AIHA diagnosis based on the medical report. The included patients were screened for thromboembolic events (TEE) and have been stratified in groups with and without complement activation based on the positivity for complement in the DAT.

Results

Of the 77 included patients, 51 (66%) had warm AIHA, 13 (17%) cold‐AIHA, 5 (7%) mixed AIHA, and 8 (10%) atypical AIHA, respectively. Primary and secondary AIHA was diagnosed in 44% and 56%, respectively. Twenty patients (26%) suffered from TEE. The majority (80%) of these patients suffered from warm AIHA and 10% from cold‐AIHA. Hemolysis parameters did not differ in patients with and without TEE. There was no correlation with complement activation as evidenced by a positivity for complement in the monospecific DAT with the occurrence of TEE.

Conclusion

AIHA is associated with an increased risk of TEE. Based on these results prophylactic anticoagulation might be considered as soon as the diagnosis of AIHA is confirmed.

Targeting the Urokinase-Type Plasminogen Activator Receptor (uPAR) in Human Diseases With a View to Non-invasive Imaging and Therapeutic Intervention

The interaction between the serine protease urokinase-type plasminogen activator (uPA) and its glycolipid-anchored receptor (uPAR) focalizes plasminogen activation to cell surfaces, thereby regulating extravascular fibrinolysis, cell adhesion, and migration. uPAR belongs to the Ly6/uPAR (LU) gene superfamily and the high-affinity binding site for uPA is assembled by a dynamic association of its three consecutive LU domains. In most human solid cancers, uPAR is expressed at the invasive areas of the tumor-stromal microenvironment. High levels of uPAR in resected tumors or shed to the plasma of cancer patients are robustly associated with poor prognosis and increased risk of relapse and metastasis. Over the years, a plethora of different strategies to inhibit uPA and uPAR function have been designed and investigated in vitro and in vivo in mouse models, but so far none have been implemented in the clinics. In recent years, uPAR-targeting with the intent of cytotoxic eradication of uPAR-expressing cells have nonetheless gained increasing momentum. Another avenue that is currently being explored is non-invasive imaging with specific uPAR-targeted reporter-molecules containing positron emitting radionuclides or near-infrared (NIR) florescence probes with the overarching aim of being able to: (i) localize disease dissemination using positron emission tomography (PET) and (ii) assist fluorescence guided surgery using optical imaging. In this review, we will discuss these advancements with special emphasis on applications using a small 9-mer peptide antagonist that targets uPAR with high affinity.

Advancing therapeutic complement inhibition in hematologic diseases: PNH and beyond

Complement is an elaborate system of the innate immunity. Genetic variants and autoantibodies leading to excessive complement activation are implicated in a variety of human diseases. Among them, the hematologic disease paroxysmal nocturnal hemoglobinuria (PNH) remains the prototype model of complement activation and inhibition. Eculizumab, the first-in-class complement inhibitor, was approved for PNH in 2007. Addressing some of the unmet needs, a long-acting C5 inhibitor, ravulizumab, and a C3 inhibitor, pegcetacoplan have been also now approved with PNH. Novel agents, such as factor B and factor D inhibitors, are under study with very promising results. In this era of several approved targeted complement therapeutics, selection of the proper drug needs to be based on a personalized approach. Beyond PNH, complement inhibition has also shown efficacy and safety in cold agglutinin disease (CAD), primarily with the C1s inhibitor of the classical complement pathway, sutimlimab, but also with pegcetacoplan. Furthermore, C5 inhibition with eculizumab and ravulizumab, as well as inhibition of the lectin pathway with narsoplimab, are investigated in transplant-associated thrombotic microangiopathy (TA-TMA). With this revolution of next-generation complement therapeutics, additional hematologic entities, such as delayed hemolytic transfusion reaction (DHTR) or immune thrombocytopenia (ITP), might also benefit from complement inhibitors. Therefore, this review aims to describe state-of-the-art knowledge of targeting complement in hematologic diseases focusing on: a) complement biology for the clinician, b) complement activation and therapeutic inhibition in prototypical complement-mediated hematologic diseases, c) hematologic entities under investigation for complement inhibition, and d) other complement-related disorders of potential interest to hematologists.

Cerebrovascular Complications of Anemia

PURPOSE OF THE REVIEW

Anemia has been called the fifth cardiovascular risk factor. It is one of the most prevalent pathologies worldwide. In this article, we aimed to perform a narrative review of the main cerebrovascular complications of anemia and its influence on stroke prognosis.

RECENT FINDINGS

Both hypoproliferative anemia (thalassemia, iron deficiency anemia, etc.) and hyperproliferative anemia (sickle cell disease, paroxysmal nocturnal hemoglobinuria, hereditary spherocytosis, etc.) are associated to cerebrovascular disease ranging from transient ischemic attack to ischemic stroke and hemorrhagic stroke with both intraparenchymal hemorrhage and subarachnoid hemorrhage or cerebral venous thrombosis. Anemia is associated to a worse prognosis in patients with cerebrovascular disease In some cases, like sickle cell disease, pathophysiological mechanisms and therapeutic guidelines are well established, while in others, due to their rarity, there are still lack of robust data. More studies are needed to clarify how the prognosis of stroke patients with anemia could be improved.

Clonal hematopoiesis and bone marrow failure syndromes

Bone marrow failure syndromes (BMF) are a group of conditions characterized by inefficient hematopoiesis frequently associated with extra-hematopoietic phenotypes and variable risk of progression to myeloid malignancies. They can be acquired or inherited and mediated by either cell extrinsic factors or cell intrinsic impairment of hematopoietic stem cell (HSC) function. The pathophysiology includes immune-mediated attack (e.g., acquired BMFs) or germline defects in DNA damage repair machinery, telomeres maintenance or ribosomes biogenesis. (e.g., inherited BMF). Clonal hematopoiesis (CH) that frequently accompanies BMF may provide a mechanism of improved HSC fitness through the evasion of extracellular pressure or somatic reversion of germline defects. The mechanism for the CH selective advantage differs depending on the condition in which it occurs. However, this adaptation mechanism, particularly when involving putative oncogenes or tumor suppressors, may lead to increased risk of myeloid malignancies. Surveillance and early detection of leukemogenic clones may lead to timely implementation of curative therapies and improved survival.

Pegcetacoplan: First Approval

Pegcetacoplan (Empaveli™) is a PEGylated pentadecapeptide developed by Apellis Pharmaceuticals for the treatment of complement-mediated diseases. It binds to complement component 3 (C3) and its activation fragment C3b, controlling the cleavage of C3 and the generation of the downstream effectors of complement activation and thus both C3b-mediated extravascular haemolysis and terminal complement-mediated intravascular haemolysis. Pegcetacoplan is the first C3-targeted paroxysmal nocturnal haemoglobinuria (PNH) therapy to be approved (in May 2021) in the USA, where it is indicated for the treatment of adults with PNH, including those switching from C5 inhibitor therapy with eculizumab and ravulizumab. A regulatory assessment of pegcetacoplan for the treatment of PNH is currently underway in the EU and Australia. Pegcetacoplan is also being investigated as a therapeutic option in other complement-mediated diseases, including age-related macular degeneration, C3 glomerulopathy and autoimmune haemolytic anaemia. The recommended dosage regimen of pegcetacoplan is 1080 mg twice weekly, administered as a subcutaneous infusion via an infusion pump with a ≥ 20 mL reservoir. This article summarizes the milestones in the development of pegcetacoplan leading to this first approval for the treatment of adults with PNH.

Efficacy and Safety of Eculizumab for Paroxysmal Nocturnal Hemoglobinuria: A Systematic Review and Meta-Analysis

BACKGROUND

Eculizumab is indicated for the treatment of paroxysmal nocturnal hemoglobinuria (PNH). This study aimed to evaluate the efficacy and safety of eculizumab in patients with PNH.

METHODS

PubMed, EMBASE, The Cochrane Library, and ClinicalTrials.gov were searched for prospective interventional studies treating PNH with eculizumab. The primary outcome was the change in lactate dehydrogenase (LDH) levels, whereas secondary outcomes included the change in hemoglobin (Hb) levels, transfusion rates, and adverse drug events.

RESULTS

Patients (n=235) from 6 studies were included in this meta-analysis. LDH and Hb levels and transfusion rates decreased significantly at 12, 26 weeks, 12, 15, and >15 months. The most frequent adverse events included nasopharyngitis (effect size [ES]: 0.53; 95% confidence intervals [CI]: 0.47 to 0.60; P=0.00), headache (ES: 0.47; 95% CI: 0.25 to 0.69; P=0.00), upper respiratory tract infection (ES: 0.37; 95% CI: 0.27 to 0.46; P=0.00), nausea (ES: 0.31; 95% CI: 0.24 to 0.38; P=0.00), fatigue, diarrhea, cough, pyrexia, abdominal pain, pain in extremities, and contusion.

CONCLUSION

Eculizumab is an effective and well-tolerated treatment for patients with PNH. It is effective at decreasing LDH levels and transfusion rates while increasing Hb levels. Further studies are needed to explore the safety of eculizumab.

Real-World Healthcare Resource Utilization (HRU) and Costs of Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH) Receiving Eculizumab in a US Population

INTRODUCTION

To evaluate the economic burden and treatment patterns of patients with paroxysmal nocturnal hemoglobinuria (PNH) treated with eculizumab, a C5 inhibitor, who were defined as blood transfusion-dependent (TD) versus blood transfusion-free (TF) in the US population.

METHODS

Patients aged at least 12 years with at least two claims for eculizumab infusion (first claim was the index date) were identified from the IBM® MarketScan® Research Databases (April 1, 2014-September 30, 2019). The overall PNH eculizumab user cohort was stratified into the TD cohort (i.e., at least one claim for blood transfusion within 6 months following any eculizumab infusion, including on the infusion date) or the TF cohort (i.e., all non-TD patients). Treatment patterns, healthcare resource utilization (HRU), and costs were evaluated and compared during follow-up (i.e., index date to end of enrollment or data availability).

RESULTS

Of 151 patients in the overall cohort (mean age 36.7 years; 55.6% female), 55 were TD (mean age 35.1 years; 67.3% female) and 96 were TF (mean age 37.6 years; 49.0% female). A total of 61% of patients (TD, 66%; TF, 58%) discontinued eculizumab, with TD patients having a shorter median time to discontinuation (TD, 0.5 years; TF, 0.9 years). TD patients had more all-cause hospitalizations than TF patients (p < 0.05). TD patients incurred higher all-cause direct medical costs (adjusted cost difference = $247,848) and medical-related absenteeism costs (adjusted cost difference = $4186) than TF patients (all p < 0.05), largely driven by hospitalizations. Similar trends were observed for PNH-related HRU and costs.

CONCLUSIONS

The economic burden of patients with PNH treated with eculizumab is greater among those dependent on blood transfusions.

Heme Burden and Ensuing Mechanisms That Protect the Kidney: Insights from Bench and Bedside

With iron at its core, the tetrapyrrole heme ring is a cardinal prosthetic group made up of many proteins that participate in a wide array of cellular functions and metabolism. Once released, due to its pro-oxidant properties, free heme in sufficient amounts can result in injurious effects to the kidney and other organs. Heme oxygenase-1 (HO-1) has evolved to promptly attend to such injurious potential by facilitating degradation of heme into equimolar amounts of carbon monoxide, iron, and biliverdin. HO-1 induction is a beneficial response to tissue injury in diverse animal models of diseases, including those that affect the kidney. These protective attributes are mainly due to: (i) prompt degradation of heme leading to restraining potential hazardous effects of free heme, and (ii) generation of byproducts that along with induction of ferritin have proven beneficial in a number of pathological conditions. This review will focus on describing clinical aspects of some of the conditions with the unifying end-result of increased heme burden and will discuss the molecular mechanisms that ensue to protect the kidneys.

Advances in the creation of animal models of paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a disease caused by a phosphatidylinositol glycan anchor biosynthesis class A (PIG-A) mutation in hematopoietic stem cells. There are three theories about the possible mechanism of the pathogenesis of PNH: immune escape, anti-apoptotic mechanism, and secondary gene mutation. There has been little gain in the knowledge regarding its pathogenesis during the last decade owing to the lack of representative cell lines and animal models. There have been recent reports about the successful creation of PNH mouse and PNH rhesus macaque models. The detection of glycosylphosphatidylinositol-anchor protein (GPI-AP)-deficient cells and/or fluorescently labeled variant of aerolysin (FLAER) test, estimation of erythrocyte life span, and hemolysis-related experiments demonstrated that these animal models of PNH had GPI-AP-deficient blood cells with shortened lifespans and increased sensitivity to complement-activated hemolysis. However, there were no clinical manifestations such as hemolysis and thrombosis in these animal models. This suggested that the PIG-A mutation is one of the several conditions required for PNH, but it alone is not enough to cause PNH.

Cost-Utility Analysis of Eculizumab for the Treatment of Paroxysmal Nocturnal Hemoglobinuria from the Perspective of the Brazilian Public Health System

OBJECTIVE

To perform a first cost-utility analysis of eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria from the perspective of the Brazilian Unified Health System.

METHODS

A Markov decision model was developed for 35-year-old patients with symptomatic paroxysmal nocturnal hemoglobinuria. We used a cycle length of one month and a time horizon of 20 years. The effectiveness measure was the quality-adjusted life year (QALY). Data were extracted from clinical trials, historical cohorts, and Unified Health System databases. Resource use and costs were estimated from the perspective of the Unified Health System. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

The estimated gain in effectiveness with the use of eculizumab was 1.08 QALY through the incremental cost of R$10,959,375.95. The incremental cost-effectiveness ratio was R$10,139,542.84 per QALY, being 331.92 times greater than the Brazilian gross domestic product per capita. In the deterministic sensitivity analysis, the parameters related to the utilities of health states were associated with greater impact in the model. The results of the probabilistic sensitivity analysis with 1000 simulations evidence that 100% of the simulations were not considered cost-effective with the arbitrated willingness to pay R$30,548.40 and R$91,645.20 per QALY.

CONCLUSIONS

The gain in effectiveness with the use of eculizumab was modest, associated with an unjustifiable incremental cost. Therefore, eculizumab is not a cost-effective drug compared with the current standard of care in the treatment of paroxysmal nocturnal hemoglobinuria from the Brazilian Unified Health System perspective.

Time and residual hematopoiesis are crucial for PNH clones escape in hepatitis-associated aplastic anemia

The presence of paroxysmal nocturnal hemoglobinuria (PNH) clones in aplastic anemia (AA) suggests immunopathogenesis, but when and how PNH clones emerge and proliferate are unclear. Hepatitis-associated aplastic anemia (HAAA) is a special variant of AA, contrarily to idiopathic AA, in HAAA the trigger for immune activation is clearer and represented by the hepatitis and thus serves as a good model for studying PNH clones. Ninety HAAA patients were enrolled, including 61 males and 29 females (median age 21 years). Four hundred three of idiopathic AA have been included as controls. The median time from hepatitis to cytopenia was 50 days (range 0-180 days) and from cytopenia to AA diagnosis was 26 days (range 2-370 days). PNH clones were detected in 8 HAAA patients (8.9%) at diagnosis and in 73 patients with idiopathic AA (IAA) (18.1%). PNH cells accounted for 4.2% (1.09-12.33%) of red cells and/or granulocytes and were more likely to be detected in patients with longer disease history and less severe disease. During follow-up, the cumulative incidence of PNH clones in HAAA increased to 18.9% (17/90). Nine HAAA patients newly developed PNH clones, including six immunosuppressive therapy (IST) nonresponders. The clone size was mostly stable during follow-up, and only 2 of 14 patients showed increased clone size without proof of hemolysis. In conclusion, PNH clones were infrequent in newly diagnosed HAAA, but their frequency increased to one that was similar to the IAA frequency during follow-up. These results suggest that the PNH clone selection/expansion process is dynamic and takes time to establish, confirming that retesting for PNH clones during follow-up is crucial.

Halting targeted and collateral damage to red blood cells by the complement system

The complement system is an important defense mechanism against pathogens; however, in certain pathologies, the system also attacks human cells, such as red blood cells (RBCs). In paroxysmal nocturnal hemoglobinuria (PNH), RBCs lack certain complement regulators which sensitize them to complement-mediated lysis, while in autoimmune hemolytic anemia (AIHA), antibodies against RBCs may initiate complement-mediated hemolysis. In recent years, complement inhibition has improved treatment prospects for these patients, with eculizumab now the standard of care for PNH patients. Current complement inhibitors are however not sufficient for all patients, and they come with high costs, patient burden, and increased infection risk. This review gives an overview of the underlying pathophysiology of complement-mediated hemolysis in PNH and AIHA, the role of therapeutic complement inhibition nowadays, and the high number of complement inhibitors currently under investigation, as for almost every complement protein, an inhibitor is being developed. The focus lies with novel therapeutics that inhibit complement activity specifically in the pathway that causes pathology or those that reduce costs or patient burden through novel administration routes.