PB2226 PHILADELPHIA‐NEGATIVE MYELOPROLIFERATIVE NEOPLASMS, CLINICAL MANIFESTATION AND OUTCOME. EXPERIENCE AT HOSPITAL ITALIANO DE BUENOS AIRES
Authors: R. Aguilar, G. Bendek, M. Barzallo, E. Brulc, M. Perusini, N. Schutz, E. Nucifora
Journal: HemaSphere (2019)

Background: BCR‐ABL negative myeloproliferative neoplasms(MPNs) are a heterogeneous group of clonal hematopoietic disorders including polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (MF) and prefibrotic primary myelofibrosis (prePMF). Clinically they share the characteristics of hypercellular bone marrow, increased incidence of thrombosis or hemorrhage and a higher rate of transformation to acute leukemia. There are scare data about latin american population, due to the scarce data available we conducted a study to evaluate patient characteristics and outcomes in the region. Aims: Primary endpoint was to evaluate the association between molecular and laboratory characteristics and the presence of thrombosis. Secondary endpoint was to evaluate time to leukemia transformation and global survival. Methods: Observational retrospective cohort study conducted at a Universal hospital in Buenos Aires. All patients evaluated between January 2004 and December 2017 with a diagnosis of MNPs confirmed by biopsy were included. Clinical and molecular data were extracted from the electronic medical history. Survival analysis was performed with Kaplan Meier curves and cox regression model using IBM SPPS software. Results: Two hundred and sixty four patients were included in the analysis. Patients characteristics are shown in table 1. A mutational state was performed in 194 patients(73.5%),132 were JAK2 V617F mutated, 6 cases had CALR mutation type 1 (3MF and 3ET), in 2 cases the CALR mutation type 2 was detected (1MF and 1ET), 2 patients presented the MPL mutation (1MF and TE) and 17 patients were triple negative. In PV, the JAK2 V617F mutation was detected in 88% of the patients analyzed, in ET and in MF 60% were positive for this mutation. Fifty two patients (19,6%) presented thrombotic events: thirty seven patients (13.9%) presented venous thrombosis, eleven patients (4.1%) arterial events, four patients (1.5%) presented both arterial and venous event. We found no significant association between thrombosis and JAK2 mutation, LDH, leukocytosis or platelet count.The risk of venous thrombosis was higher in PV (HR 1.92 CI 95% 0.90‐4.07) and FM HR 1.18 (CI 95% 0.54 a 2.61) than ET. There were not difference in arterial event between the three groups (OR 1.5, p0.47). Fourteen patients (5,3%) suffer transformation: seven patients (2.6%) evolved to AML, of them 2 had initial diagnosis of PV, 4 of MF and 1 patients of ET. Seven patients progressed to MF, two with previous diagnosis of PV and five with ET. The median time of transformation in the total population was 196 months, in ET it was also of 196 months. There were not relationship between age, hemoglobin value, leukocyte count and the risk of disease transformation. At the end of the follow‐up, 94% of the PV and the 96.3% of the MF, have not reach the median of progression‐free survival. The median follow‐up of the entire cohort was 53 months, 47 months for PV, 48 months for ET and 31,5 month for MF. Forty nine patients (18,6%) died. The median overall survival for the entire cohort was 288 months. Summary/Conclusion: The analysis showed that the characteristics of our population are similar to those reported in the literature, with rates of global survival and transformation similar to the global population, in PV and MF and higher in ET. image