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.

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a non-malignant clonal disease of hematopoietic cells with a complex pathophysiology and variable clinical spectrum, characterized by signs and symptoms related to intravascular hemolysis, hypercoagulability, and cytopenias. Metaboloma is the end product of an organism's genetic configuration plus the influence of all factors to which it is exposed. Metabolomic profile is able to provide a more accurate functional measure of a phenotype formed by the result of genomic, transcriptomic and proteomic changes. Aims: To compare a metabolomic profile in the PNH hemolytic group with healthy controls, and to compare a metabolomic profile before and after the administration of eculizumab in PNH patients. Methods: To perform metabolomic profile, we used mass spectrometry in 23 patients with hemolytic PNH and in 166 healthy adults, as control group. Twelve PNH patients samples were also collected before and 24 hours after receiving eculizumab. Liquid chromatography with mass spectrometry was performed using the AbsoluteIDQ P180 Biocrates kit (Biocrates, Life Science AG, Innsbruck, Austria): 186 metabolites from 7 different classes were identified and quantified. The data were imported to the analytical site MetaboAnalyst 4.0 and ROCCET: ROC Curve Explorer & Tester for the generation of Univariate and Multivariate Operational Characteristic curves of the Receiver (ROC). Results: In the patients with hemolytic PNH, of the 186 metabolites analyzed, 92 of them showed significant differences between patients and controls, with positive or negative correlation. The major metabolites increased in the PNH group were long-chain acylcarnitines, while the major metabolites reduced in the PNH group were histidine, taurine, glutamate, glutamine, aspartate and phosphatidylcholines. The C14:1/C16:1 ratio lower than 1.4 was shown to be a reliable marker in patients with PNH, suggesting a disorder in lipid elongation. Besides, PNH patients had a significant increase in C6:1 levels and C14:1/C6 and C4/C6 ratios. After receiving eculizumab, patients reached levels comparable to those of normal subject. Conclusion: We observed differences in the metabolome of PNH patients as compared to healthy controls, suggesting a unique metabolomic profile of these patients, characterized by an altered acylcarnitine balance, reduction in aminoacids participating in the glycogenesis pathway and an impaired glutaminolysis. Acylcarnitines levels seem to significantly reduce with the use of eculizumab, demonstrating that the use of the antibody has action in reducing hemolysis and possibly in mitochondrial function of these patients. Disclosures No relevant conflicts of interest to declare.