Phosphatidylinositol Glycan Class A Research Articles

No Benefits from Glucocorticoid Maintenance Therapy in Patients with PNH

Introduction Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, complement-mediated hemolytic anemia resulting from a somatic phosphatidylinositol glycan class A ( PIGA) mutation which bugs the biosynthesis of glycosylphosphatidylinositol (GPI). The lack of GPI-anchored proteins, especially CD55 and CD59 molecules, prompts blood cells to be prone to complement attack and lysis. Targeted on the terminal complement inhibitor has been recommended as a first-line treatment, such as eculizumab (C5 inhibitors), which not only controls hemolytic anemia, reduces thrombosis and blood transfusion, but also improves the staging status of chronic kidney disease in PNH patients. Complement inhibitors are not yet widely administrated by Chinese PNH patients, so glucocorticoids are still mostly used for the first-line treatment. However, the efficacy of glucocorticoid maintenance therapy in PNH is uncertain. Methods We conducted a prospective self-controlled comparison of 40 PNH patients with high disease activity (HDA), collecting anemia, hemolysis, thrombosis and renal function indicators at baseline and 1st, 3rd and 6th month after treatment in the Chinese Eastern Collaboration Group of Anemia (CECGA). All enrolled patients were administrated with prednisone 1.0 mg/kg/d at first and then adjusted the dosage according to the situation. The clinical trial registration number is ChiCTR2100050945. Results A total of 40 patients with PNH were enrolled in this study, 21 (52.5%, 21/40) were male, 19 (47.5%, 19/40) were female and the median age was 33.5 years (range 18-69 years). 29 of 40 (72.5%) presented classical PNH and 11 patients (27.5%) were diagnosed as PNH associated with bone marrow disease (BMD)-10 were aplastic anemia and 1 was myelodysplastic syndrome. Four cases detected single-site thrombosis and one had multi-site thrombosis. The most common locations were portal vein thrombus (2/6, 33.33%) and lower extremity intermuscular thrombus (2/6, 33.33%), others included mesentery vein, hepatic vein, splenic vein and intracranial microthrombus. The laboratory indexes at baseline were presented in Table 1. Compared to the baseline (Table 2), at 1 st, 3 rd, and 6 th month after treatment, both hemoglobin and red blood cell (RBC) have improved, but hemoglobin and RBC didn't keep rising, and showed no difference when comparing 3 rd month with 1 st month and 6 th month with 3 rd month. 19 patients (19/40, 47.5%) required blood transfusion before treatment, and 11 patients (11/40, 27.5%) needed transfusion at 1 st month ( P=0.021). Then 13 patients (13/40, 32.5%) at 3 rd month, 15 patients (15/40, 37.5%) at 6 th month were transfusion dependent ( P=0.109; P=0.388). After 6-month treatment, 3 cases of severe anemia (Hb < 30 g/L) at baseline were still severe anemia (3/7, 42.86%), and 4 cases (4/7, 57.14%) were upgraded to moderate anemia (60 g/L ≤ Hb ≤ 90 g/L). Among the original moderate anemia, 20 (20/31, 64.52%) cases were still moderate anemia, 6 (6/31, 19.35%) cases decreased to severe anemia and 5 (5/31, 16.13%) cases were improved to mild anemia (Hb > 90 g/L). 1 (1/2, 50%) patient of mild anemia originally maintained mid anemia and one (1/2, 50%) patient decreased to moderate anemia. The levels of LDH, indirect bilirubin (IBIL) and reticulocyte (Ret) were not changed significantly at 1 st, 3 rd, 6 th month after treatment. At 1 st, 3 rd, 6 th month, only 1, 2 and 2 patients achieved hemolytic control (LDH < 1.5 ULN). The d-dimer and glomerular filtration rate (GFR) also were indicated no difference. At 1 st, 3 rd, 6 th month, 3 (3/11, 27.27%), 4 (4/11, 36.36%), 6 (6/11, 54.54%) patients were back to normal range, 1 (1/11, 9.09%), 2 (2/11, 18.18%), 4 (4/11, 36.36%) patient was newly elevated (D-dimer > 0.55 mg/L) separately. At baseline 2 patients' renal function was severely reduced (GFR＜60ml/min/1.73m 2), and at 1 st, 3 rd, 6 th month, 1, 1, 2 patients had declined respectively. Discussions and Conclusions The use of prednisone in PNH patients with HDA may initially improve anemia, but the improvement in anemia may also be due to self-remission after paroxysmal episodes of PNH itself, or transfusion. The maintenance therapy with prednisone cannot control hemolysis, improve thrombosis and renal function damage. Long-term glucocorticoid maintenance therapy for PNH is not recommended.

Neutrophil Functionalities in Patients with Paroxysmal Nocturnal Haemoglobinuria Are Not Affected By Complement C5- Inhibition

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare, acquired haematological stem cell disorder characterized by haemolysis, thrombophilia, and cytopenia. PNH is caused by a somatic mutation in the phosphatidylinositol glycan class A (PIG-A) gene at the level of pluripotent, hematopoietic stem cells leading to a lack of GPI anchored cell surface proteins, such as complement-inactivating proteins, (e.g., CD55, CD59) on stem cells, polymorphonuclear neutrophil granulocytes (PMN), erythrocytes, and platelets. Subsequently, uncontrolled complement overactivity leads to the systemic complications. Phenotypic mosaicism is a distinct characteristic of PNH. For diagnostic purposes, the absence of the GPI-anchor on granulocytes and monocytes in the flow cytometry is considered the gold standard. However, the exact consequences of GPI deficiency in PMNs and monocytes have not been studied sufficiently yet. Since the implementation of complement inhibitors, the primary cause of morbidity and mortality in PNH has been significantly reduced. Despite this, the tendency towards thrombosis, as well as the consequences of the deficiency of GPI-linked proteins on PMNs and monocytes, remain largely unclear. Therefore, the main objective of this project is to gain a deeper understanding of the impact of PNH-PMNs and monocytes on thrombo-inflammation in PNH. Specifically, the impact of complement inhibitors on these factors has been compared. Blood from PNH patients (n=14) with a median clone size of 74 % were compared with an age- and sex-matched control group (n =20). Various cellular markers indicating a state of activation (CD11b, TREM1, CD64) or showing platelet adherence (CD42), were measured using flow cytometry. Unmutated PMNs and monocytes from PNH patients (PMN) served as intrinsic control, GPI positive PMNs (WT-PMN (PNH)) and monocytes from a control group served as extrinsic control. We compared unstimulated PNH and WT cells for their basal phenotype, and then functional changes upon stimulation (phorbol 12-myristate 13-acetate (PMA)). Our data present a contrary perspective to our initial assumptions, indicating that PNH-PMNs have a direct impact on unmutated PMNs, resulting in the generation of a thrombogenic state and increased levels of activation. The unmutated GPI-positive PMNs and monocytes exhibit a significantly stronger direct aggregation with platelets compared to GPI-deficient clones. It is hypothesized that the PNH clones influence the activity and aggregation propensity of the remaining unmutated granulocytes through additional cellular mechanisms. In a subgroup analysis, the impact of complement factor 5 inhibitors (C5i) on the aforementioned factors was investigated detecting no significant differences in terms of PMN activation or platelet aggregation. Thus, it can be hypothesized that thrombosis and hyper-inflammation are not solely driven by the PNH clones directly and modulated C5 inhibition. Additional cellular mechanisms and signaling pathways appear to play an important role, and these aspects have not been adequately addressed by the current therapy.

The PIG-A gene mutation assay in human biomonitoring and disease.

The blood cell phosphatidylinositol glycan class A (PIG-A) gene mutation assay has been extensively researched in rodents for in vivo mutagenicity testing and is now being investigated in humans. The PIG-A gene is involved in glycosyl phosphatidylinositol (GPI)-anchor biosynthesis. A single mutation in this X-linked gene can lead to loss of membrane-bound GPI anchors, which can be enumerated via corresponding GPI-anchored proteins (e.g., CD55) using flow cytometry. The studies published to date by different research groups demonstrate a remarkable consistency in PIG-A mutant frequencies. Moreover, with the low background level of mutant erythrocytes in healthy subjects (2.9-5.56 × 10-6 mutants), induction of mutation post genotoxic exposure can be detected. Cigarette smoking, radiotherapy, and occupational exposures, including lead, have been shown to increase mutant levels. Future applications of this test include identifying new harmful agents and establishing new exposure limits. This mutational monitoring approach may also identify individuals at higher risk of cancer development. In addition, identifying protective agents that could mitigate these effects may reduce baseline somatic mutation levels and such behaviors can be encouraged. Further technological progress is required including establishing underlying mechanisms of GPI anchor loss, protocol standardization, and the development of cryopreservation methods to improve GPI-anchor stability over time. If successful, this assay has the potential be widely employed, for example, in rural and low-income countries. Here, we review the current literature on PIG-A mutation in humans and discuss the potential role of this assay in human biomonitoring and disease detection.

Measuring blood cell DNA damage using the PIG-A mutation and CBMN assay in pancreatic cancer patients: a pilot study.

Pancreatic cancer still has one of the worst prognoses of all solid malignancies, despite developments in cancer knowledge and care. Research into pancreatic cancer has not fully translated into clinical improvements and as a result, fewer than 1% of patients survive 10 years post-diagnosis. This bleak outlook for patients could be improved by earlier diagnosis. The human erythrocyte phosphatidylinositol glycan class A (PIG-A) assay monitors the mutation status of the X-linked PIG-A gene by measuring glycosyl phosphatidylinositol (GPI)-anchored proteins on the extracellular surface. We have previously identified an elevated PIG-A mutant frequency in oesophageal adenocarcinoma patients and here investigate whether this could be seen in a pancreatic cancer cohort, given the urgent need for novel pancreatic cancer biomarkers. In our pilot study, an elevated PIG-A mutant frequency (5.775 × 10-6 (95% CI 4.777-10) mutants per million) was seen in pancreatic cancer patients (n = 30) when compared to the non-cancer control group (n = 14) who had an erythrocyte mutant frequency of 4.211 × 10-6 (95% CI 1.39-5.16) mutants per million (p = 0.0052). A cut-off value of 4.7 mutants per million provided an AUROC of 0.7595 with a sensitivity of 70% and specificity of 78.57%. A secondary measure of DNA damage in an alternative blood cell population also showed an increase in peripheral lymphocytes using the cytokinesis-block micronucleus assay (p = 0.0164) (AUROC = 0.77, sensitivity = 72.22%, specificity = 72.73%). The micronucleus frequency and PIG-A status show some potential as blood-based biomarkers of pancreatic cancer, but further investigations of these DNA damage tests are required to assess their utility in pancreatic cancer diagnosis.

Inpatient Burden, Characteristics and Outcomes Associated with Venous Thrombotic Complications Among Patients with Paroxysmal Nocturnal Hemoglobinuria

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, clonal hematopoietic stem cell disease caused by mutations in an X-linked gene called phosphatidylinositol glycan class A (PIG-A). Venous thromboembolism (VTE) is known to be a leading cause of death in patients with PNH and is considered to be a clinical emergency, warranting treatment with eculizumab and therapeutic anticoagulation. Although several studies have analyzed the overall disease burden and predictors of outcomes associated with VTE in patients with PNH, data on inpatient burden and outcomes are scarce. We sought to investigate the inpatient burden, characteristics and overall outcomes associated with VTE-related complications among patients with PNH using a large nation-wide database. Methods: The current nation-wide retrospective analysis was conducted using the National Inpatient Sample (NIS), which includes administrative and demographic data from a 20% sample of inpatient hospitalizations in the United States. We interrogated the NIS for admissions among patients with PNH from 2016-2019 using appropriate ICD-10 diagnosis codes. Admissions with known hypercoagulable conditions such as anti-phospholipid antibody syndrome, factor V Leiden mutation, prothrombin gene mutation, protein C and S deficiency, etc. were excluded. Hospitalizations with PNH were further assessed for VTE-related complications using appropriate ICD-10 codes and data on baseline characteristics and inpatient outcomes were collected and analyzed. Chi-square test was used for categorical data and Student's t-test was used for continuous variables. A p-value < 0.05 was considered statistically significant. SAS version 9.4 (SAS Institute Inc.) was used for statistical analysis. Results: A total of 3,600 hospitalizations were included for analysis, out of which, 345 (9.6%) were associated with VTE. Lower extremity deep vein thrombosis (DVT) was noted to be the most common (100/345, 29%) followed by hepatic vein thrombosis/ Budd Chiari syndrome (80/345, 23.2%), portal vein thrombosis (70/345, 20.3%), pulmonary embolism (60/345, 17.4%), upper extremity DVT (60/345, 17.4%), non-specific VTE (15/345, 4.3%) and renal vein thrombosis (5/345, 1.5%). Table 1 shows baseline characteristics and co-morbidities in hospitalizations associated with and without VTE. Patients in the VTE group were significantly younger (47.3±17.4 vs 50.4±22.1, p=0.01) and had a higher prevalence of co-morbid obesity (27.5% vs 10.1%, <0.001) and chronic liver disease (23.2% vs 8.3%, p<0.001). The prevalence of myelodysplastic syndrome (5.8% vs 11.4%, p=0.002) and aplastic anemia (20.3% vs 27.2%, p=0.006) was noted to be significantly lower in the VTE group, while no difference was noted with iron deficiency anemia (4.3% vs 4.1%, p=0.85) and primary myelofibrosis (2.9% vs 1.5%, p=0.06). No patients with acute myeloid leukemia could be captured in our cohort in either of the groups. Overall, there was no difference in all-cause inpatient mortality between groups with and without VTE (1.4% vs 2.5%, p=0.24), however, hospitalizations with VTE-related complications were associated with longer average length of stay (10 days vs 6.3 days, p<0.001), higher average cost of hospitalizations ($178,143 vs $100,547, p<0.001) and lower rate of discharge to home (66.7% vs 72.5%, p=0.02). Conclusions: Overall, 10% of the hospitalizations in our analysis were associated with VTE, out of which, lower extremity DVT, hepatic and portal vein thrombosis were the most common sites (approximately 75% of the VTE burden). Patients with VTE were younger and had a higher prevalence of co-morbid obesity and chronic liver disease. Prevalence of myelodysplastic syndrome and aplastic anemia was noted to be significantly lower in the VTE group, however, further prospective clinical data are needed to analyze the impact of these diagnoses on overall risk of VTE in patients with PNH. Although VTE did not appear to increase all-cause inpatient mortality; associated increase in average length of stay, average cost of hospitalization and decreased likelihood of discharge to home were noted. Concerted efforts to strengthen and enhance care for patients with PNH in the ambulatory setting are needed to prevent inpatient hospitalizations with VTE and reduce associated healthcare burden and costs. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Prospective Self-Control Analysis of Glucocorticoid Maintenance Therapy for Paroxysmal Nocturnal Hemoglobinuria

Background Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, complement-mediated hemolytic anemia caused by a somatic phosphatidylinositol glycan class A (PIGA) gene mutation on the X chromosome of hematopoietic stem cells. The mutation of PIGA gene destroys the biosynthesis of glycosylphosphatidylinositol (GPI), resulting in the lack of GPI anchor proteins, including CD55 and CD59 molecules, in hematopoietic stem cells and their progeny cells (erythrocytes, granulocytes, monocytes, lymphocytes). Erythrocyte membrane without CD55 and CD59 are prone to complement attack and lysis[1]. PNH presents as hemolytic anemia, bone marrow failure, and thrombosis, and so on. Targeting the terminal complement inhibitor, such as eculizumab (C5 inhibitors), could not only control hemolytic anemia, reduce thrombosis and transfusion, improve the staging status of chronic kidney disease, and prevents the deterioration of renal function in PNH patients. However, eculizumab has not yet been available in mainland of China, glucocorticoids is still used as the first-line therapy in China. Methods From September 2020 to April 2022, 26 PNH patients with high disease activity (HAD) were enrolled in the study. Oral prednisone was initiated at a dose of 1mg/kg/day and gradually tapered four weeks later. Clinical characteristics of patients was described in Table 1. Results The hemoglobin paired T-test results before treatment and at 1 month, 3 months, and 6 months after treatment were as follows: (69.12±14.83) vs (77.50±18.11), p＜0.05；(69.12±14.83) vs (74.15±18.23), p=0.15；(69.12±14.83) vs (75.54±19.91), p=0.09; paired chi-square test (McNemar Test) for anemia stratification (>90g/L, 60-90g/L, <60g/L) showed no marked changes: p=0.082, p=0.344, p=0.247; By Friedman Test, it showed reticulocyte percentage was also similar: (6.76±3.92) vs (6.23±4.08) vs (6.62±3.92) vs (7.11±4.73), p=0.457. Before treatment, 25 patients (25/26, 96.15%) were transfusion dependent. After treatment at 1 month, 3 months, 6 months, 19 patients (19/26, 73.08%), 22 patients (22/26, 84.62%), 21 patients (21/26, 80.77%) were transfusion dependent, respectively (p=0.031; p=0.375; p=0.219). Two patients progressed to transfusion dependent at 3 months, 6months, respectively. No patients achieved remission of hemolysis (LDH < 1.5 ⅹULN) at 1, 3, and 6 months; the level of lactate dehydrogenase and indirect bilirubin (IBIL) showed no changes by analysis with Friedman test (p=0.436, p=0.881). By Friedman test, the serum level of D-dimer also showed no changes at different times ( p=0.263). Level of D-dimer elevated (>0.55mg/L) in seven patients before treatment, and returned back within normal range in one patient at 1 month, two patients at 3 months, three patients at 6 months. But among the people with normal D level initially, one patient and three patients each had elevated D-dimer level at 3 months and 6 months, respectively. Two patients achieved renal function improvement at 3 months, 6months, respectively. But three patients had renal function deterioration after treatment. Glomerular filtration rate (GFR) was (114.15±42.98) ml/min/1.73m2 before treatment, and become (117.79±37.69) ml/min/1.73m2, (120.85±44.05) ml/min/1.73m2, (110.30±36.58) ml/min/1.73m2 at 1, 3, and 6 months (p=0.42, p=0.43, p=0.41). Discussion Previous studies have mainly compared the improvement of anemia after breakthrough of PNH by glucocorticoids therapy. The improvement of anemia could not be ruled out as a result of transfusion support or the reduction of temporary hemolysis after breakthrough of PNH. We found the level of LDH increased along with improvement of hemoglobin during prednisone treatment, and percentage of reticulocytes was not changed at same time. It suggested that the improvement of anemia in some patients may not be caused by controlling intravascular hemolysis or the compensatory hyperplasia of the bone marrow, but by transfusion. Conclusions It preliminarily showed prednisone maintenance therapy for PNH could not control hemolysis and thrombosis, and could not improve anemia and renal function. The efficacy of glucocorticoid maintenance therapy in PNH is uncertain. Reference: [1] Brodsky R A. How I Treat Paroxysmal Nocturnal Hemoglobinuria[J]. Blood, 2021, 137(10): 1304-1309. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Phase 2, Open-Label Study Evaluating the Safety and Efficacy of Combination Pozelimab and Cemdisiran Therapy in Patients with Paroxysmal Nocturnal Hemoglobinuria Who Switch from Eculizumab

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is an ultra-rare, acquired disorder caused by a mutation in the phosphatidylinositol glycan class A (PIGA) gene, which leads to impaired expression of complement-regulating proteins on the surface of hematopoietic cells. Clinical presentation of PNH includes hemolytic anemia, hemoglobinuria, and thrombosis. Complement component C5 inhibitors such as eculizumab are part of the current standard of care for patients with PNH; however, this is an intravenous treatment which relies on nurse administration. In addition, some patients experience an incomplete response to therapy, and may still experience breakthrough hemolytic events. Pozelimab and cemdisiran are investigational agents with a subcutaneous maintenance regimen that may be self-administered. Both agents act together to inhibit terminal complement through complementary mechanisms of action. Pozelimab is a fully human monoclonal antibody inhibitor of C5, while cemdisiran is an N-acetylgalactosamine-conjugated small interfering RNA (siRNA) that suppresses liver production of C5. The efficacy and safety of the combination of pozelimab and cemdisiran is being evaluated in an ongoing, phase 2, open-label single-arm study in patients with PNH who switch from eculizumab therapy (NCT04888507). The interim safety and preliminary efficacy results are presented here. Methods: This ongoing phase 2 trial consists of a screening period (up to 42 days), a 32-week open-label treatment period (OLTP), an optional 52-week open-label extension period, and a 52-week post-treatment safety follow-up period. Patients transitioned from eculizumab therapy to the combination of pozelimab and cemdisiran over a 4-week period, and thereafter received the combination (pozelimab 400 mg and cemdisiran 200 mg) subcutaneously every 4 weeks. Results: At the time of this interim data analysis (data cut-off March 18, 2022) six patients were enrolled and five patients were ongoing. While one patient discontinued after 29 days of treatment, the remaining five patients had a treatment duration of at least 169 days, with one completing the OLTP (Day 225). Up to the time of data cut-off, no patient had a lactate dehydrogenase (LDH) level greater than 1.5 x the upper limit of normal (ULN; Figure 1) or experienced an event of breakthrough hemolysis, including the two patients who were previously treated with higher doses of eculizumab (1200 mg and 1500 mg every 2 weeks, respectively). Furthermore, all but two LDH values remained normal (≤1.0 x ULN) at all timepoints evaluated. All patients achieved hemoglobin stabilization. CH50, a measure of terminal complement activity, remained fully suppressed at 0 kIU/L throughout the study up to the time of the data cut-off. There were no serious or severe treatment emergent adverse events (TEAEs). Importantly, there were no meningococcal infections or adverse events due to potential large drug-target-drug immune complexes, or TEAEs leading to death, in this study. One patient discontinued study treatment due to two mild, non-serious TEAEs of headache at Days 2 and 16. Conclusions: These interim results from a limited data set suggest that in patients with PNH transitioning from eculizumab treatment, including patients treated with higher than standard of care doses, the combination of pozelimab and cemdisiran was generally well tolerated, providing sustained control of intravascular hemolysis without any breakthrough hemolysis events. These findings support the ongoing development of pozelimab and cemdisiran combination therapy. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

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

ABSTRACT 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.

Baseline Assessment of Patients with Newly-Diagnosed Acquired Bone Marrow Failure Enrolled in a Prospective Observational Study, “Search for Unidentified Links between PNH Clone Size and the Related Clinical Manifestations By High Precision Flow Cytometry (SUPREMACY)”

Introduction:Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disorder characterized by an acquired mutation(s) of the phosphatidylinositol glycan class A (PIGA) gene, leading to expansion of glycosylphosphatidylinositol-anchored protein deficient blood cells (PNH-type cells). By using high-resolution flow cytometry established by our group, PNH-type cells can also be detected at low frequencies (less than 1%) in some patients with acquired bone marrow failure (BMF) such as aplastic anemia (AA) and lower-risk myelodysplastic syndromes (MDS). Although the presence of a small number of PNH-type cells has been shown to be associated with a favorable response to immunosuppressive therapy and good prognosis in patients with BMF (Blood 2006, 107:1308-1314; Br J Haematol 2014, 164:546-54), the clinical significance of the PNH-type cell population in the clinical course of BMF remains unclear. Japan PNH Study Group is conducting a nation-wide multicenter prospective observational study for newly-diagnosed patients with BMF in Japan, SUPREMACY (Search for unidentified links between PNH clone size and the related clinical manifestations by high precision flow cytometry). We herein report an interim analysis of the baseline data of this study.Methods:Patients newly diagnosed with PNH, AA, MDS or unclassified BMF are recruited to the study from April 2016 until March 2020 in Japan. The percentage of PNH-type cells in peripheral blood is measured by high-resolution flow cytometry at the time of enrollment and repeated every year for 3 years. Combination of antibodies against the lineage markers and liquid FLAER or cocktail antibodies against CD55 and CD59 were used for the detection of PNH-type cells in granulocytes (Gr) (≥0.003%) or erythrocytes (Ery) (≥0.005%) and monocytes (Mo) (≥0.01%), respectively. Moreover, to explore the relationship between the presence of PNH-type cells and specific clinical manifestations, we collected clinical laboratory test data on iron metabolism, coagulation, renal function and cardiac function and surveyed physical conditions of the patients using the health-related quality of life (HRQOL) questionnaires targeted to the management of chronic illness in those patients at baseline; measurements will also be repeated every year for 3 years. This study was approved by the research ethics board of each institution.Results: As of March 2017, 314 patients (162 female [52%]) were examined; 129 (41.1%) were positive for PNH-type cells in all of Gr, Ery and Mo, and 38 (12.1%) had PNH-type cells ≥1%. The median age (min, max) was 67 (18, 86) vs 65 (16, 100) years for patients with vs without PNH clones, respectively. There was no significant difference in physical conditions between two groups. Out of 314, 162 (52%) patients were diagnosed to have AA (n=72), MDS (n=78), and PNH (n=12) based on the case report forms. PNH-type cells were detected in 59.7%, 29.5% and 100% of patients with AA, MDS (33.3% for RCUD, 26.5% for RCMD, and 0% for RARS and RAEB) and PNH, respectively. PNH clone size was significantly correlated between each cell lineage (correlation coefficient, 0.861 for Gr vs Ery, 0.886 for Gr vs Mo and 0.855 for Ery vs Mo). The PNH clone size in Ery was smaller than those in Gr or Mo. Half of the patients with PNH-type cells ≥1%, the serum lactate dehydrogenase levels exceeded the ≥1.5×upper limits of normal. Interestingly, the total iron binding capacity (TIBC) significantly correlated with the PNH-type cell population in Gr, Ery or Mo (p<0.0001). In addition, there was a negative correlation between other iron metabolism markers (serum ferritin and iron) and the PNH-type Ery population (p<0.01). These results may be explained by iron loss due to clinical or subclinical intravascular hemolysis in a manner dependent upon the PNH clone size.Conclusion: High-resolution flow cytometry could identify PNH-type cells not only in Gr/Ery, but also Mo in about 40% of BMF patients enrolled in SUPREMACY. Frequency of patients positive for PNH-type cells in each disease was similar to those reported in previous studies (about 60% in AA, 20~30% in lower-risk MDS, and 0% in RARS or RAEB). The study will continue to enroll up to 1500 patients, and further monitor the PNH clone size and the concomitant clinical information in the following three years. DisclosuresYonemura:Alexion Pharma GK: Honoraria, Research Funding. Kawaguchi:Alexion Pharma GK: Honoraria, Research Funding. Ishiyama:Alexion Pharma GK: Research Funding. Sugimori:Alexion Pharma GK: Honoraria. Obara:Alexion Pharma GK: Honoraria, Research Funding. Noji:Alexion Pharma GK: Honoraria, Research Funding. Shirasugi:Novartis Pharma GK: Honoraria. Ueda:Alexion Pharma GK: Honoraria, Research Funding. Shichishima:Alexion Pharma GK: Honoraria. Chiba:Nippon Shinyaku: Honoraria, Research Funding. Ninomiya:Alexion Pharma GK: Honoraria. Ando:MOCHIDA PHARMACEUTICAL: Other: Donation to institute; TOYAMA CHEMICAL: Other: Donation to institute; NOVARTIS: Other: Donation to institute; Meiji Seika Pharma: Other: Donation to institute; CHUGAI PHARMACEUTICAL: Other: Donation to institute; Sumitomo Dainippon Pharma: Other: Donation to institute; Eisai: Other: Donation to institute; Bristol-Myers Squibb: Other: Donation to institute; MSD: Other: Donation to institute; Kyowa Hakko Kirin: Other: Donation to institute; ALEXION: Other: Donation to institute; Takeda: Other: Donation to institute; Asahi KASEI: Other: Donation to institute; TAIHO: Other: Donation to institute; NIHON PHARMACEUTICAL: Other: Donation to institute; Nippon Shinyaku: Other: Donation to institute; Japan Blood Products Organization: Other: Donation to institute. Nishimura:Alexion Pharma GK: Honoraria, Research Funding. Kanakura:Astellas: Research Funding; Bristol Myers: Research Funding; Alexion Pharmaceuticals, Inc.: Honoraria, Research Funding; Fujimotoseiyaku: Research Funding; Pfizer: Research Funding; Toyama Chemical: Research Funding; Kyowa Hakko Kirin: Research Funding; Nippon Shinyaku: Research Funding; Eisai: Research Funding; Shionogi: Research Funding; Chugai Pharmaceutical: Research Funding. Takahashi:Alexion Pharma GK: Employment.

The importance of flow cytometry in the diagnosis and monitoring of paroxysmal nocturnal hemoglobinuria

ABSTRACT Introduction: The paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal disease of the hematopoietic stem cells, and it is clinically characterized by chronic intravascular hemolysis, bone marrow failure and hypercoagulability leading to thrombosis. It is a rare disorder of the hematopoietic stem cells that occurs due to a somatic mutation in the gene phosphatidylinositol glycan class A (PIG-A). Objective: Here we reviewed the importance of screening and monitoring of individuals with high risk of developing PNH, since the early diagnosis of the disease is essential for better prognostic and treatment choice for the patient. Method: A review was carried out with great focus on the pathophysiology and diagnosis of PNH, mainly with the use of flow cytometry technique to detect the disease. Results: This gene codifies an enzyme essential to the formation of glycosylphosphatidylinositol (GPI), which acts as a molecular anchor for many membrane proteins. The alteration of GPI synthesis promotes a partial or complete loss of proteins that needs this molecular anchor to bind to the cell surface. Among these proteins are the CD55 and the CD59, which control the activation of the complement cascade. Conclusion: The immunophenotyping exam with flow cytometry is considered the reference test for PNH diagnosis, since the technique is highly sensitive and specific, presenting advantages as the quantitative identification of small populations of cells with PNH phenotype and the capacity to distinguish cells with partial or total deficiency of GPI-anchored proteins.

Dietary and lifestyle factors effect erythrocyte PIG-A mutant frequency in humans.

It is well understood that poor diet and lifestyle choices can increase the risk of cancer. It is also well documented that cancer is a disease of DNA mutations, with mutations in key genes driving carcinogenesis. Measuring these mutations in a minimally invasive way may be informative as to which exposures are harmful and thus allow us to introduce primary preventative measures, in a bid to reduce cancer incidences. Here, we have measured mutations in the phosphatidylinositol glycan class A (PIG-A) gene in erythrocytes from healthy volunteers (n = 156) and from non-cancer patients attending the local endoscopy department (n = 144). The X-linked PIG-A gene encodes an enzyme involved in glycosylphosphatidylinositol (GPI) anchor synthesis. A silencing mutation in which leads to the absence of GPI anchors on the extracellular surface which can be rapidly assessed using flow cytometry. The background level of PIG-A mutant erythrocytes was 2.95 (95% CI: 2.59-3.67) mutant cells (10-6). Older age increased mutant cell frequency (P < 0.001). There was no difference in mutant cell levels between males and females (P = 0.463) or smokers and non-smokers (P = 0.186). In the endoscopy group, aspirin users had lower mutant frequencies (P = 0.001). Further information on diet and exercise was available for the endoscopy patient group alone, where those with a higher health promotion index score had lower mutant frequencies (P = 0.011). Higher dietary intake of vegetables reduced mutant cell levels (P = 0.022). Participants who exercised for at least 1 h a week appeared to have reduced mutant frequencies than those who did not exercise, although this was not statistically significant (P = 0.099). This low background level of mutant erythrocytes in a population makes this assay an attractive tool to monitor exposures such as those associated with lifestyles and diet, as demonstrated here.

Complement Inhibition Therapy and Dialytic Strategies in Paroxysmal Nocturnal Hemoglobinuria: The Nephrologist's Opinion.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal disease that presents an estimated incidence of 1.3 cases per million per year, with a prevalence of 15.9 cases per million. It is characterized by hemolysis, bone marrow dysfunction with peripheral blood cytopenia, hypercoagulability, thrombosis, renal impairment and arterial and pulmonary hypertension. Hemolysis and subsequent hemosiderin accumulation in tubular epithelium cells induce tubular atrophy and interstitial fibrosis. The origin of PNH is the somatic mutation in the X-linked phosphatidylinositol glycan class A (PIG-A) gene located on Xp22: this condition leads to the production of clonal blood cells with a deficiency in those surface proteins that protect against the lytic action of the activated complement system. Despite the increased knowledge of this syndrome, therapies for PNH were still only experimental and symptomatic, until the introduction of the C5 complement blockade agent Eculizumab. A second generation of anti-complement agents is currently under investigation, representing future promising therapeutic strategies for patients affected by PNH. In the case of chronic hemolysis and renal iron deposition, a multidisciplinary approach should be considered to avoid or treat acute tubular injury or acute kidney injury (AKI). New promising perspectives derive from complement inhibitors and iron chelators, as well as more invasive treatments such as immunoadsorption or the use of dedicated hemodialysis filters in the presence of AKI.

PIG-a Mutations in a Brazilian Cohort of Patients with Paroxysmal Nocturnal Hemoglobinuria

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a disorder due to an acquired loss-of-function mutation in the phosphatidylinositol glycan class A (PIG-A) gene. A large spectrum of acquired PIG-A mutations has been described, like insertions or deletions involving a single base or several bases, and single base substitution that are the most common. Usually there are more than one PIGA mutations and one clone is predominant. The clinical manifestations of PNH are intrinsically related to clonal expansion of hematopoietic stem cell deficient in GPI-anchored proteins. Some hypothesis failed to explain alone this clonal expansion. Here we try to identify and to correlate PIG-A gene mutations with clinical manifestations in a series of patients with PNH. Methods: We analyzed 31 patients with classical PNH (n=23) or aplastic anemia and PNH clone (n=8). The sequencing of the PIG-A gene was performed using the Sanger technique. The electropherograms were aligned against the reference sequence of the PIG-A gene deposited in GenBank (Accession number NG_009786), and analyzed using the Geneious R10 software (Biomatters). After analysis, a search was performed in the Clinvar, dbSNP and HGMD databases to verify the pathogenicity of the mutations. For variants without description in the literature, a pathogenicity prediction analysis was performed using Mutation Taster, Polyphen 2 and Human Splicing Finder software. Results: We found 29 different variants of the PIG-A gene in 27 patients: 23 were new mutations, with no previous description in the literature, 3 were previously described mutations, and 3 were single nucleotide polymorphism (SNP). There was great variation in the type and location of somatic mutations. Mutations were predominantly small deletions and simple base changes; 42% of the mutations were described as frameshift mutations and 31% missense mutations. We did not find any specific correlation between the clinical characteristics of hemolytic PNH patients and their mutations, due to the wide variety of mutations. According the pathogenicity prediction programs, the majority (22 of 29) of the variants found were classified as probably pathogenic. Among the 23 patients with hemolytic PNH, 19 patients had at least one mutation classified as pathogenic. In patients with subclinical PNH, only SNPs were found. Fifteen patients with hemolytic PNH had more than one concomitant mutation, most of which were probably pathogenic mutations associated with a polymorphism. Conclusion: We described PIG-A mutations in a series of PNH patients in Brazil and observed no correlation exists between mutation types and clinical features in hemolytic patients. Among subclinical PNH patients, only SNPs were observed, probably because of small clone sizes. Disclosures No relevant conflicts of interest to declare.

Clinical Characteristics of Brazilian Patients with Paroxysmal Nocturnal Hemoglobinuria and Changing Prognosis with Eculizumab

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disease of hematopoietic cells due to acquired mutations in the phosphatidylinositol glycan class A (PIG-A) gene, which is required for glycosylphosphatidylinositol (GPI) anchor biosynthesis. This leads to partial or complete absence of all GPI-linked proteins, who are complement regulatory proteins, resulting in an increased sensitivity of the red blood cells to the action of complement. PNH is characterized by signs and symptoms related to intravascular hemolysis, hypercoagulability state, and varying degrees of medullary insufficiency. The anti-complement therapy radically changed the PNH patients outcomes. However, there are little data on the clinical characteristics of PNH in Latin American countries. Methods: We performed a retrospective analysis of 109 patients with PNH clone followed from January 1987 until July 2019 in two Brazilian centers: Universidade Federal de Sao Paulo and Hospital Sirio Libanes (Sao Paulo-Brazil). Most patients (88%) were evaluated while the others had lost follow up or died and data was obtained from their medical reports. Patients were separated into 3 groups: classical PNH (n=44) PNH associated with other bone marrow disorder(n=12), and subclinical PNH, defined as PNH clone (at least 0.01% of cells with PNH clone) associated with another bone marrow disorder (n=53, aplastic anemia in 95% of cases). Median follow up was 60 months (range: 3-394). Results: Median age at diagnosis was 41 years (range: 18-81), and 51% were male. Among the 56 patients with hemolytic PNH, 86% had fatigue, 66% hemoglobinuria, 45% abdominal pain and 16% dysphagia. Venous thromboembolism was observed in 14 cases (25%), with abdominal thrombosis in 7 cases (50%). Seven patients (13%) had arterial thrombosis (stroke or transient ischemic attack). Only 5 patients (10%) in the hemolytic group had acute renal failure and needed dialysis therapy due to a hemolytic crisis, but progressed to recovery of renal function after the event. No patient in this series had moderate or severe chronic kidney disease. Most hemolytic patients (73%) were treated with eculizumab, with a median time from diagnosis to the start of eculizumab of 25 months (range: 2-275). All eculizumab-treated patients had significant reduction in intravascular hemolysis with lactate dehydrogenase (LDH) normalization. Most had significant improvement in anemia, with increase in the median hemoglobin from 9.1 g/dL before treatment to 11.7 g/dL after eculizumab. The vast majority (94%) became transfusion-independent. Overall survival (OS) at 5 years was 100% at 5 years for classical PNH (n=44), 89% for subclinical PNH (n=53) and 71% for PNH associated with another bone marrow disease (n=12). Conclusion: The clinical data and the distribution of the three subtypes of PNH in this study in this large series of Brazilian PNH patients were similar to other published series, except for a lower frequency of venous or arterial thrombosis in hemolytic patients before eculizumab treatment and a lower frequency of chronic kidney disease in our series. We also confirmed in our series the efficacy of eculizumab in controlling hemolysis and PNH-related complications and death risk. Disclosures No relevant conflicts of interest to declare.

The impact of missense mutation in PIGA associated to paroxysmal nocturnal hemoglobinuria and multiple congenital anomalies-hypotonia-seizures syndrome 2: A computational study

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal blood disorder that manifests with hemolytic anemia, thrombosis, and peripheral blood cytopenias. The disease is caused by the deficiency of two glycosylphosphatidylinositols (GPI)-anchored proteins (CD55 and CD59) in the hemopoietic stem cells. The deficiency of GPI-anchored proteins has been associated with the somatic mutations in phosphatidylinositol glycan class A (PIGA). However, the mutations that do not cause PNH is associated with the multiple congenital anomalies-hypotonia-seizures syndrome 2 (MCAHS2). To best of our knowledge, no computational study has been performed to explore at an atomistic level the impact of PIGA missense mutations on the structure and dynamics of the protein. Therefore, we focused our study to provide molecular insights into the changes in protein structural dynamics upon mutation. In the initial step, screening for the most pathogenic mutations from the pool of publicly available mutations was performed. Further, to get a better understanding, pathogenic mutations were mapped to the modeled structure and the resulting protein was subjected to 100 ns molecular dynamics simulation. The residues close to C- and N-terminal regions of the protein were found to exhibit greater flexibility upon mutation. Our study suggests that four mutations are highly effective in altering the structural conformation and stability of the PIGA protein. Among them, mutant G48D was found to alter protein's structural dynamics to the greatest extent, both on a local and a global scale.

Developing a blood-based gene mutation assay as a novel biomarker for oesophageal adenocarcinoma

The Phosphatidylinositol glycan class A (PIG-A) gene mutation assay phenotypically measures erythrocyte mutations, assessed here for their correlation to neoplastic progression in the gastro-oesophageal reflux disease (GORD)-Barrett’s metaplasia (BM)-oesophageal adenocarcinoma (OAC) model. Endoscopy patients underwent venipuncture and erythrocytes fluorescently stained for glycosyl phosphatidylinositol (GPI)–anchored proteins; CD55 and CD59. Using flow cytometry, GPI–anchor negative erythrocytes (mutants) were scored and compared amongst groups. The study enlisted 200 patients and 137 healthy volunteers. OAC patients had a three–fold increase in erythrocyte mutant frequency (EMF) compared to GORD patients (p < 0.001) and healthy volunteers (p < 0.001). In OAC patients, higher EMF was associated with worsening tumour staging (p = 0.014), nodal involvement (p = 0.019) and metastatic disease (p = 0.008). Chemotherapy patients demonstrated EMF’s over 19–times higher than GORD patients. Patients were further classified into groups containing those with non-neoplastic disease and those with high-grade dysplasia/cancer with 72.1% of cases correctly classified by high EMF. Within the non-neoplastic group, aspirin users had lower EMF (p = 0.001) and there was a positive correlation between body mass index (p = 0.03) and age (p < 0.001) and EMF. Smokers had EMF’s over double that of non-smokers (p = 0.011). Results suggest this test could help detect OAC and may be a useful predictor of disease progression.

Insights into Clonal Relationships of Putative Adaptive Natural Killer Cells (NK) in Humans, Via Mapping of Somatic Piga Mutations in Patients with Paroxysmal Nocturna Hemoglobinuria (PNH)

NK cells play a central role in innate immunity, specifically in tumor surveillance and microbial pathogen control. Recent murine models and human studies have identified subsets of NK-cells with apparent memory cell function, strongly linked to CMV infection in humans and termed "adaptive" NK. Our recent clonal tracking studies following autologous hematopoietic stem cells transplantation (HSCT) of genetically-barcoded CD34+ cells in macaques revealed distinct clonal ontogeny of a subset of NK cells within the primate equivalent of the human CD56dim population (Wu et al., Cell Stem Cell, 2014), with little clonal overlap with T-, B-lymphoid or myeloid cells, suggesting a separate precursor pool for this NK subtype. Peripheral blood CD 56bright -NK cells have been previously hypothesized to be precursors for the main population of circulating cytotoxic CD56dim cells. To further investigate NK-cell ontogeny and clonal relationships in humans we took advantage of naturally-occurring somatic mutations in the X-linked phosphatidylinositol glycan class A (PIGA) gene in patients with the hemolytic disorder paroxysmal nocturnal hemoglobinuria. This gene codes for an enzyme required for cell surface localization of glycosylphophatidylinositol (GPI)-anchored proteins, and thus loss of function mutations result in hematopoietic cells lacking GPI-anchored proteins, and red cell hemolysis. PNH patients have not been reported to have immune dysfunction and can have stable disease for many years. Membrane bound GPI anchors can be detected on any cell via flow cytometry using a labeled inactive aerolysin (FLAER), and serves as a marker for the fraction of cells comprising the PIGA mutant (GPI negative) clonal compartment. The PNH clone sizes contributing to peripheral blood cells are variable in but can reach almost 100% in some patients, and can be stable over decades. We selected 9 PNH patients with GPI negative granulocytes ranging from 5% to 98% and a median time from diagnosis of 43.7 months (15-100) for this study. NK cells were defined as CD56+/CD16+/CD3-/CD20- lymphocytes. We observed disproportionally fewer GPI negative NK cells compared to granulocytes (Fig 1), with the discrepancy most marked the major peripheral blood CD56dim population (mean 65% vs 25% GPI negative granulocytes, p = 0.0028, paired t-test), in contrast to 46% GPI negative cells in the CD56bright population (p=0.057). Due to the prolonged life span of memory T and B cells, fewer GPI negative B and particularly T-lymphocytes have been reported in PNH patients. In our cohort 3.4% of CD3+ T-cells and 13.2% of CD20+ B-cells were GPI negative (p=0.0005 and 0.0014, respectively versus granulocytes). Compared to the NK subsets, the CD56bright population showed the most significant differences (p = 0.0063 versus CD3 and p=0.0151 versus CD20). To further characterize the phenotype of the GPI positive versus negative CD56dim cells, we analyzed cells co-expressing either the terminal differential marker CD57, the inhibitory receptor NKG2A, or activating receptor NKG2C for FLAER positivity. Prior studies have suggested that the human CMV-linked adaptive NK subset is CD57+, NKG2A- and NKG2C+. The NKG2C+ CD 56dim population was highly enriched for GPI positive cells (p=0.0024 vs granulocytes, Fig 1). This profile was most prominent in CMV-IgG positive patients who had also significantly more GPI positive CD 56dim/CD57+ cells compared to granulocytes (p=0.008). Interestingly, one CMV positive patient (#5) had a complete lack of NKG2C expression, most likely due to homozygous loss of function mutation, and this patient had almost 100% GPI negative NK cells, matching his neutrophil pattern. Compared to granulocytes, NKGA2A+ or CD57+ positive CD56dim cells were also mostly GPI negative (p=0.0081 and 0.028).Circulating NK cell turnover has been estimated to be about 14 days. The PNH patients studied had documented clonal PIG-A mutations for many years. Our observation that the majority of CD56dim NK cells, specifically the NKG2C subset, are not progeny of the same progenitors producing CD56bright NK cells or myeloid cells based on clonal disparity regarding the PNH clone is suggestive of an independent, very long-lived or self-renewing NK cell progenitor for a CMV-linked CD56dim/CD57+/NKG2C+ memory NK cell compartment. These observations provide novel further insights into the human adaptive NK cell subset. [Display omitted] DisclosuresWinkler:Novartis: Research Funding; GSK: Research Funding. Townsley:Novartis: Research Funding; GSK: Research Funding.

An Interim 4-Year Analysis of Prospective Multicenter Observational Study of PNH-Type Cells in Japanese Patients with Bone Marrow Failure Syndrome (OPTIMA study)

Background: Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder caused by the clonal expansion of the phosphatidylinositol glycan class A (PIGA) mutant hematopoietic stem cells, which results in a deficiency in glycosylphosphatidylinositol-anchored proteins (GPI-APs). Through the high-resolution flow cytometry-based method, GPI-APs deficient blood cells (i.e., PNH-type cells) are often detectable in patients with bone marrow failure syndromes (BMF), such as aplastic anemia (AA) and low-risk types of myelodysplastic syndromes (MDS). Sugimori et al reported that when BMF patients possessed increased PNH-type cells, the patients had a good prognosis and showed a high response rate to immunosuppressive therapies, suggesting that detection of PNH-type cells is potentially useful in determining an optimal treatment for BMF patients. Thus, we conducted a nationwide, multi-center prospective observational investigation, the OPTIMA study.Methods: From July 2011, we start recruiting the patients with BMF that were diagnosed at various hematology clinics throughout Japan to the OPTIMA study. The primary endpoint of this study was to determine the prevalence of BMF patients with PNH-type cells and to clarify the clinical significance of the presence and quantitative changes of these cells with regard to the clinical features. Six different university laboratories were assigned as regional analyzing centers. The percentage of PNH-type cells was measured by the high-resolution flow cytometry-based method, originally established in Kanazawa University. At six individual laboratories, cross validations were conducted twice a year to minimize the inter-laboratory variations in the detection sensitivities, cutoff values, etc. The liquid FLAER method (≥0.003%) and cocktail method (≥0.005%) with CD55 and CD59 antibodies were used for the detection of PNH-type granulocytes and erythrocytes, respectively.ResultsBetween July 2011 and May 2015, a total of 2328 patients were enrolled to this study, and we analyzed 2212 patients who were eligible for the interim analysis. Of these patients, 74 (3.3%) were diagnosed with PNH, 690 (31.2%) with AA, 592 (26.8%) with MDS, and 856 (38.7%) with undiagnosed BMF. Using high-resolution flow cytometry-based method, 755 (34.1%; 95.9% in PNH, 52.8% in AA, 18.2% in MDS, and 24.8% in undiagnosed BMT) patients had ≥0.005% PNH-type erythrocytes and ≥0.003% PNH-type granulocytes. Overall, 181(8.2%) patients had ≥1% of both PNH-type erythrocytes and granulocytes; the prevalence in each disease subset was 68/74 (91.9%) in PNH, 67/690 (9.7%) in AA, 22/592 (3.7%) in MDS, and 24/856 (2.8%) in undiagnosed BMF. Regarding FAB and WHO classifications of MDS subtype, no patients with RARS (0/22), RAEB-1 (0/37) or RAEB-2 (0/23) had PNH-type cells. In contrast, 20.4% (56/275) patients with RCMD, 18.3% (26/153) patients with RCUD and 50% (2/4) patients with del (5q) MDS possessed increased PNH-type cells. Blood samples from 75 (65 with and 10 without PNH-type cells) patients were analyzed three years after the first examination. Of 65 PNH (+) patients, PNH-type cells disappeared in 4 (6.2%), while the percentage remained stable in 61 (93.8%). All of the 10 PNH (-) at the enrollment were also negative for PNH-type cells in 3 years.Conclusions: A high-resolution flow cytometry-based method that enables the detection of minimal PNH-type cells below 0.01% was successfully transferred from Kanazawa University to other laboratories in Japan. Our interim analysis confirmed previous findings that PNH-type cells were detectable in patients with 52.8% of AA and 18.2% of MDS patients. Regarding FAB and WHO classifications of MDS subtype, PNH-type cells were not detected in any of MDS RARS, RAEB-1 or RAEB-2 patients. Further analysis are required to determine the clinical significance of the minimal level of PNH-type cells as well as chronological changes in the PNH-type cell percentage, especially in terms of their relation to response to immunosuppressive therapy. DisclosuresNinomiya:Alexion Pharmaceuticals: Honoraria. Ando:Eisai Co., Ltd.: Honoraria, Research Funding. Yonemura:1. Chugai Pharma, 2. Alexion Pharma, 3. Japan Blood Products Organization, 4. OHARA Pharma: Research Funding. Kawaguchi:Alexion Pharmaceuticals: Honoraria. Ueda:Alexion Pharma: Research Funding. Nishimura:Alexion Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

L’hémoglobinurie paroxystique nocturne : une cause méconnue de thrombose ?

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder of hematopoietic stem cells. Somatic mutation in the phosphatidylinositol glycan class A (PIG-A), X-linked gene, is responsible for a deficiency in glycosphosphatidylinositol-anchored proteins (GPI-AP). The lack of one of the GPI-AP complement regulatory proteins (CD55, CD59) leads to hemolysis. The disease is diagnosed with hemolytic anemia, marrow failure and thrombosis. Thromboembolic complication occurs in 30% of patient after 10 years of follow-up and is the first event in one out of 10 patients. The two most common sites are hepatic and cerebral veins. These locations are correlated with high risk of death. Currently, these data are balanced with the use of a monoclonal antibody (Eculizumab), which has significantly improved the prognosis with a survival similar to general population after 36 months of follow-up. Anticoagulant treatment is recommended after a thromboembolic event but has no place in primary prophylaxis.

The Interim Analysis of the Optima (observation of GPI-anchored protein-deficient [PNH-type]) Cells in Japanese Patients with Bone Marrow Failure Syndrome and in Those Suspected of Having PNH) Study

[Background] Paroxysmal nocturnal hemoglobinuria (PNH) is a hematopoietic　stem cell disorder derived from an acquired mutation of the phosphatidylinositol glycan class A (PIGA) gene in the hematopoietic stem cells which results in the expansion of glycosylphospatidylinositol-anchored protein (GPI-AP)-deficient (PNH-type) hematopoietic cells. PNH-type blood cells are also observed in patients with bone marrow failure (BMF). PNH is conventionally diagnosed when patients have >1% of GPI-AP-deficient erythrocytes and granulocytes determined by flow cytometry. Analyses with high resolution flow cytometry by several different groups have shown that patients with aplastic anemia (AA) or low-risk types of myelodysplastic syndromes (MDS) have small percentages of PNH-type erythrocytes, granulocytes, and/or other lineages of blood cells and that these patients respond better to immunosuppressive therapies compared with BMF patients lacking PNH-type cells. In order to determine the prevalence and clinical significance of PNH-type cells in BMF patients, we conducted a nationwide multi-center prospective observational investigation, the OPTIMA study.[Methods] From July 2011, Japanese patients with PNH, AA, MDS or BMF of uncertain origin have been prospectively enrolled into the study. Six laboratories in different cities in Japan were assigned as regional analyzing centers and measured the percentages of PNH-type cells in the study population as well as collecting clinical and laboratory data. The high-resolution flow cytometry assessments used a liquid fluorescein-labeled proaerolysin (FLAER) method and a cocktail method with anti-CD55 and anti-CD59 antibodies for the detection of PNH-type granulocytes and erythrocytes, respectively. Periodic blind cross validation tests using a standard blood sample containing 0.01% PNH-type cells and a normal control were conducted to minimize inter-laboratory variations. From analysis of 68 healthy individuals >0.003% of PNH-type granulocytes and >0.005% of PNH-type erythrocytes were considered to be abnormal (Sugimori et al, Blood, 2006).[Results] As of May 2014, flow cytometry data have been collected from 1685 patients and are included in this interim analysis. Of these patients, 65 (4%) were diagnosed with PNH, 523 (31%) with AA, 459 (27%) with MDS, and 638 (38%) with BMF of unknown etiology. Overall, 154 (9%) patients had ≥1% of both PNH-type erythrocytes and granulocytes: 63 (97%) patients with PNH; 57 (11%) with AA; 18 (4%) with MDS; and 16 (3%) with BMF of unknown etiology. In total, 545 (32%) patients had ≥0.005% PNH-type erythrocytes and ≥0.003% PNH-type granulocytes. These consisted of the followings; all 65 (100%) patients with PNH; 264 (51%) with AA; 76 (17%) with MDS; and 140 (22%) with BMF of unknown origin. Lactate dehydrogenase (LDH) levels ≥1.5 × upper limit of normal range were seen in 14/329 (4%) patients with 0.005-1% PNH-type erythrocytes, 23/62 (37%) patients with 1-10% PNH-type erythrocytes, and 69/71 (97%) patients with ≥10% PNH-type erythrocytes. Periodic blind validation tests revealed that inter-laboratory differences in absolute measurements of PNH-type cells were always within 0.02%.[Conclusion] A high-resolution flow cytometry-based method, based on the Kanazawa method, that enables the detection of very low percentages of PNH-type cells was successfully transferred to 6 laboratories across Japan. Our results demonstrated that the proportion of patients identified as having small percentages of PNH-type cells differed depending on diagnosis (PNH, AA, MDS, or unknown BMF) and that elevated LDH levels (>1.5 x upper limits of normal range) were more frequently associated with higher percentages of PNH-type erythrocytes. Our findings suggest that the high resolution method is helpful as a diagnostic tool in BMF syndromes, including AA, MDS, and PNH, and may prove useful in understanding the pathophysiology of these disorders. DisclosuresNoji:Alexion Pharma: Honoraria. Shichishima:Alexion Pharmaceuticals, Inc; and Medical Review Company: Honoraria, Research Funding. Obara:Alexion Pharma: Research Funding. Chiba:Alexion Pharma: Research Funding. Ando:Alexion Pharma: Research Funding. Hayashi:Alexion Pharma: Research Funding. Yonemura:Alexion Pharma: Research Funding. Kawaguchi:Alexion Pharma: Honoraria. Ninomiya:Alexion Pharma: Honoraria, Research Funding. Nishimura:Alexion Pharma: Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau. Kanakura:Alexion Pharma: Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau.