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Thrombosis and haemorrhage are frequent in patients with essential thrombocythaemia (ET). The 2016 revised International Prognostic Score for Thrombosis in Essential Thrombocythaemia-thrombosis (r-IPSET-t) score stratifies patients into very-low- (VLR), low- (LR), intermediate- (IR) and high-risk (HR) groups. We validated the r-IPSET-t in the biggest population of patients with ET (n = 1381) to date and found it to be a better fit than the earlier IPSET-t score. With an average follow-up of 87.7 months, there were 0.578 thrombotic events/person-year and 0.286 bleeding events/person-year after diagnosis. The 10-year thrombosis-free survival was 88% and 99% for the r-IPSET-t LR and VLR groups (p 0.001). Cytoreduction was a thrombotic risk factor in younger patients (aged60 years, hazard ratio 9.49, p = 0.026; aged ≥60 years, hazard ratio 1.04, p = 0.93). In multivariable Cox regression analysis, anti-aggregation after diagnosis was protective for thrombosis (hazard ratio 0.31, p = 0.005) but a risk factor for major bleeding (hazard ratio 10.56, p = 0.021). Of the IPSET-t HR and LR groups, 132/780 and 249/301 were re-classified as LR and VLR respectively (p 0.001). The European LeukemiaNET (ELN) does not recommend aspirin for VLR patients but in this real-life analysis 83.1% of VLR patients received it. Our results validate the r-IPSET-t score as more predictive for thrombosis than the ELN-recommended IPSET-t and raise concerns about unnecessary cytoreductive and anti-aggregative therapy.

Clinical trials have demonstrated that some patients with chronic myeloid leukemia (CML) treated for several years with tyrosine kinase inhibitors (TKIs) who have maintained a molecular response can successfully discontinue treatment without relapsing. Treatment free remission (TFR) can be reached by approximately 50% of patients who discontinue. Despite having similar levels of deep molecular response and an identical duration of treatment, the factors that influence the successful discontinuation of CML patients remain to be determined. In this review we will explore the factors identified to date that can help predict whether a patient will successfully achieve TFR. We will also discuss the need for the identification of predictive biomarkers associated with a high probability of achieving TFR for the future personalized identification of patients who are suitable for the discontinuation of TKI treatment.

Resumen Antecedentes y objetivo La mielofibrosis es una neoplasia mieloproliferativa cronica infrecuente. Nuestro objetivo fue describir las caracteristicas clinico-biologicas, el tratamiento y el curso evolutivo de los pacientes con mielofibrosis en Espana. Material y metodos Se analizaron 1.000 pacientes del Registro Espanol de Mielofibrosis diagnosticados de mielofibrosis primaria (n = 641) o secundaria (n = 359). Resultados La mediana de edad era de 68 anos. La frecuencia de sintomatologia constitucional, anemia moderada o severa (Hb Conclusiones la mielofibrosis es una enfermedad invalidante que afecta sobre todo a personas de edad avanzada y cuyo tratamiento es fundamentalmente sintomatico. A pesar de su heterogeneidad clinica se dispone de modelos pronosticos utiles para la seleccion de candidatos a trasplante.

BACKGROUND AND OBJECTIVE MYELOFIBROSIS: is an infrequent chronic myeloproliferative neoplasm. We aimed to describe the clinico-biological characteristics, treatment, and evolutive course of myelofibrosis patients in Spain.; MATERIAL AND METHODS: A total of 1,000 patients from the Spanish Registry of Myelofibrosis diagnosed with primary (n=641) or secondary (n=359) myelofibrosis were analysed.; RESULTS: Median age was 68 years. The frequency of constitutional symptoms, moderate to severe anaemia (Hb

Advances in Next-Generation Sequencing technologies (NGS) are revealing germline and somatic mutations that, together with karyotype, determine the diagnosis and subtype of Acute Myeloid Leukemia (AML). Molecular testing is also essential for the genetic risk stratification of patients with AML, in particular for those with normal karyotype AML (CN-AML), a large and highly heterogeneous group of patients. Patients determined to be at high risk could benefit from a more aggressive first-line therapy, or a more directed therapy, such as midostaurin (for FLT3-mutated AML) or ivosidenib (for IDH1-mutated AML). Here, we will summarize the molecular testing currently recommended in AML and introduce new mutations that may have prognostic value and clinical application in the near future.

Purpose of Review Clinical factors alone do not enable us to differentiate which patients will maintain treatment-free remission (TFR) from those who are likely to relapse. Thus, patient-specific factors must also play a role. This review will update the reader on the most recent studies presenting biological factors that can help predict tyrosine kinase inhibitor (TKI) discontinuation success. Recent Findings Cellular and molecular factors with a suggested role in TFR include immune factors and leukemic stem cell (LSC) persistence; the BCR::ABL1 transcript type, halving time, and BCR::ABL1 DNA and RNA positivity; as well as other molecular factors such as somatic mutations, RNA expression, and telomere length. Summary Our review presents several biomarkers with predictive value for TFR but also highlights areas of unmet need. Future discontinuation guidelines will likely include biological factors for the personalization of TFR prediction. However, it will be important that such advances do not prevent more patients from making a TKI discontinuation attempt.

Treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase (CML-CP) is considered a feasible option, especially with the ability of second-generation tyrosine kinase inhibitors to induce higher rates of sustained deep molecular response (DMR). DASFREE is an open-label, single-arm, multicenter phase II trial assessing TFR after dasatinib discontinuation in patients with CML-CP (N = 84). At 2 years, TFR was 46% in all patients. Multivariate analyses revealed statistically significant associations between 2-year TFR and duration of prior dasatinib (≥median; p = .0051), line of therapy (first line; p = .0138), and age (>65 years; p = .0012). No disease transformation occurred, and the most common adverse events experienced off treatment were musculoskeletal (observed in 30 patients); however, dasatinib withdrawal events were reported in nine patients (11%) by the investigator. Overall, these findings support the feasibility of discontinuing dasatinib for patients with CML-CP in sustained DMR in the first line and beyond.

Genetic studies in the past decade have improved our understanding of the molecular basis of the BCR-ABL1-negative myeloproliferative neoplasm (MPN) polycythaemia vera (PV). Such breakthroughs include the discovery of the JAK2V617F driver mutation in approximately 95% of patients with PV, as well as some very rare cases of familial hereditary MPN caused by inherited germline mutations. Patients with PV often progress to fibrosis or acute myeloid leukaemia, both associated with very poor clinical outcome. Moreover, thrombosis and major bleeding are the principal causes of morbidity and mortality. As a result of increasingly available and economical next-generation sequencing technologies, mutational studies have revealed the prognostic relevance of a few somatic mutations in terms of thrombotic risk and risk of transformation, helping to improve the risk stratification of patients with PV. Finally, knowledge of the molecular basis of PV has helped identify targets for directed therapy. The constitutive activation of the tyrosine kinase JAK2 is targeted by ruxolitinib, a JAK1/JAK2 tyrosine kinase inhibitor for PV patients who are resistant or intolerant to cytoreductive treatment with hydroxyurea. Other molecular mechanisms have also been revealed, and numerous agents are in various stages of development. Here, we will provide an update of the recent published literature on how molecular testing can improve the diagnosis and prognosis of patients with PV and present recent advances that may have prognostic value in the near future.

The ENESTfreedom trial assessed the feasibility of treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase (CML-CP) following frontline nilotinib treatment. Results for long-term outcomes after a 5-year follow-up are presented herein. Patients who had received ≥2 years of frontline nilotinib therapy and achieved MR4.5 underwent a 1-year nilotinib treatment consolidation phase before attempting TFR. At the 5-year data cut-off, 81/190 patients entering the TFR phase (42.6%) were still in TFR, with 76 (40.0%) in MR4.5. Patients who lost major molecular response (MMR) entered a treatment re-initiation phase; 90/91 patients entering this phase (98.9%) regained MMR and 84/91 patients (92.3%) regained MR4.5. The Kaplan–Meier estimated treatment-free survival rate at 5 years was 48.2%. No disease progression or CML-related deaths were reported. Whereas the incidence of adverse events (AEs) declined from 96 weeks following the start of TFR, an increase in AE frequency was observed for patients in the treatment re-initiation phase. Low Sokal risk score, BCR-ABL1IS levels at 48 weeks of TFR and stable MR4.5 response for the first year of TFR were associated with higher TFR rates. Overall, these results support the efficacy and safety of attempting TFR following upfront nilotinib therapy of >3 years in patients with CML-CP.

Next-Generation Sequencing has recently been introduced to efficiently and simultaneously detect genetic variations in acute myeloid leukemia. However, its implementation in the clinical routine raises new challenges focused on the diversity of assays and variant reporting criteria. To overcome this challenge, the PETHEMA group established a nationwide network of reference laboratories aimed to deliver molecular results in the clinics. We report the technical cross-validation results for next-generation sequencing panel genes during the standardization process and the clinical validation in 823 samples of 751 patients with newly diagnosed or refractory/relapse acute myeloid leukemia. Two cross-validation rounds were performed in seven nationwide reference laboratories in order to reach a consensus regarding quality metrics criteria and variant reporting. In the pre-standardization cross-validation round, an overall concordance of 60.98% was obtained with a great variability in selected genes and conditions across laboratories. After consensus of relevant genes and optimization of quality parameters the overall concordance rose to 85.57% in the second cross-validation round. We show that a diagnostic network with harmonized next-generation sequencing analysis and reporting in seven experienced laboratories is feasible in the context of a scientific group. This cooperative nationwide strategy provides advanced molecular diagnostic for acute myeloid leukemia patients of the PETHEMA group.

The authors thank Paola Romecin and Virginia Rodriguez-Cortez for technical assistance. This work was supported by the Spanish Ministry of Economy and Competitiveness (SAF2016-80481R, PID2019-108160RBI00), the Obra Social La Caixa (LCF/PR/HR19/52160011), Interreg V-A programme (POCTEFA) 2014-2020 (grant PROTEOblood EFA360/19), Health Canada (H4080-144541), and Deutsche Josep Carreras Leukämie Stiftung (P.M.). Additional funding was provided by Consejería de Salud y Familia (PI- 0119-2019) (R.D.d.l.G.), Health Institute Carlos III (ISCIII/FEDER, PI17/01028) and Asociación Española Contra el Cáncer (C.B.), Health Institute Carlos III/FEDER (CPII17/00032) (V.R.-M.), and Fundación Hay Esperanza (E.A.). CERCA/Generalitat de Catalunya and Fundación Josep Carreras-Obra Social la Caixa provided institutional support. B.L.-M. was supported by a Lady Tata Memorial Trust International Award and Asociación Española Contra el Cáncer (INVES20011LÓPE). O.M. and T.V.-H. were supported by Asociación Española Contra el Cáncer (INVES211226MOLI) and a Marie Sklodowska Curie Fellowship (792923), respectively. P.M. is an investigator in the Spanish Cell Therapy Network., Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Disease heterogeneity is well documented, and patient stratification determines treatment decisions. Patient-derived xenografts (PDXs) from risk-stratified AML are crucial for studying AML biology and testing novel therapeutics. Despite recent advances in PDX modeling of AML, reproducible engraftment of human AML is primarily limited to high-risk (HR) cases, with inconsistent or very protracted engraftment observed for favorable-risk (FR) and intermediate-risk (IR) patients. We used NSGS mice to characterize the engraftment robustness/kinetics of 28 AML patient samples grouped according to molecular/ cytogenetic classification and assessed whether the orthotopic coadministration of patientmatched bone marrow mesenchymal stromal cells (BM MSCs) improves AML engraftment. PDX event-free survival correlated well with the predictable prognosis of risk-stratified AML patients. The majority (85-94%) of the mice were engrafted in bone marrow (BM) independently of the risk group, although HR AML patients showed engraftment levels that were significantly superior to those of FR or IR AML patients. Importantly, the engraftment levels observed in NSGS mice by week 6 remained stable over time. Serial transplantation and long-term culture-initiating cell (LTC-IC) assays revealed long-term engraftment limited to HR AML patients, fitter leukemia-initiating cells (LICs) in HR AML samples, and the presence of AML LICs in the CD342 leukemic fraction, regardless of the risk group. Finally, orthotopic coadministration of patient-matched BM MSCs and AML cells was dispensable for BM engraftment levels but favored peripheralization of engrafted AML cells. This comprehensive characterization of human AML engraftment in NSGS mice offers a valuable platform for in vivo testing of targeted therapies in risk-stratified AML patient samples., Spanish Ministry of Economy and Competitiveness (SAF2016-80481R, PID2019-108160RBI00), Obra Social La Caixa (LCF/PR/HR19/52160011), Interreg V-A programme (POCTEFA) 2014-2020 (grant PROTEOblood EFA360/19), Health Canada (H4080-144541), Deutsche Josep Carreras Leukämie Stiftung, Consejer ıa de Salud y Familia (PI- 0119-2019), Health Institute Carlos III (ISCIII/FEDER, PI17/01028), Asociación Española Contra el Cáncer, Health Institute Carlos III/FEDER (CPII17/00032), Fundación Hay Esperanza, CERCA/Generalitat de Catalunya, Fundació Josep Carreras-Obra Social la Caixa, Lady Tata Memorial Trust International Award, Asociación Española Contra el Cáncer (INVES20011LÓPE), Asociación Española Contra el Cáncer (INVES211226MOLI), Marie Sklodowska Curie Fellowship (792923)

INTRODUCTION Coronavirus disease 2019 (COVID-19) caused by SARS-CoV2 virus is thought to be more severe in patients with prior hematological diseases. There is evidence suggesting that hematological patients are particularly vulnerable and have a higher risk of developing severe events, with higher mortality rate than general population. However, the available data are limited, and prognostic factors at admission still remain unclear. With this background, our aims were to analyze the impact of hematological diseases and their therapy on the COVID-19 severity and to identify clinical and biological risk factors to predict the outcome in these patients. METHODS We carried out a multicenter retrospective observational study with data collection from 19 Spanish centers. A total of 491 patients with hematological diseases who developed COVID-19 (HEMATOCOVID patients) from March 8th to June 9th were included in the study. Clinical and biological data were collected at the time of emergency room assistance or hospital admission. For statistical analysis, chi-square test and Mann-Whitney U-test were used to identify differences between groups. The effects of multiple predictor variables on COVID-19 outcomes were assessed by logistic binary regression. RESULTS The geographic distribution of the studied HEMATOCOVID patients was similar to the national geographic spread of the COVID-19 (Figure 1). Most patients (94,3%) were confirmed cases of COVID-19 with a positive result on SARS-CoV2 RT-PCR on a nasopharyngeal swab or serologic testing, and 15% were nosocomial infections. The mean age was 71 years with 57% males, and 70% had at least one associated comorbidity. The most frequent hematological diseases among COVID-19 patients were Lymphoid Malignancies (53,8%), and 51,7% of patients were on active treatment. Most common symptoms were fever (59%), cough (54%) and dyspnea (46%), with associated pneumonia in 70% of cases. Hospital admission was required in 89% of patients and 6,3% were admitted to intensive care units. Mortality rate was about 36%. Non-survival patients were older and had a higher Charlson comorbidity index and ECOG performance status. Furthermore, patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS), and those with an active or progressive hematological disease at the diagnosis of COVID-19 had higher mortality. Patients who had undergone hematopoietic stem cell transplantation (autologous, allogeneic, and both) had better outcomes. Other factors such as low lymphocyte and platelets counts, or high lactate dehydrogenase (LDH), C-reactive protein (CRP) and procalcitonin values were also associated with poorer outcomes (Table 1). In addition, COVID-19 therapy had no impact on survival, except for corticosteroids, that correlated with a negative impact (p < 0,001) probably because they were not administrated to patients with less severe COVID-19. Multivariate regression analysis showed the following risk factors for death: age >70 years, ECOG ≥2, absolute lymphocyte count ≤0.6·109/L, platelet count ≤40·109/L, high LDH (higher than upper normal limit) and CRP >11 mg/dL (Table 2). CONCLUSIONS SARS-CoV2 infection causes more severe disease and higher mortality rates in hematological patients, especially those with AML/MDS or active/progression status disease. In addition, advanced age, co-morbidities, poor performance status, low lymphocyte and platelet counts and high LDH and CRP at admission are associated with poorer survival. This worse disease evolution could be explained by the immunosuppression state induced by underlying disease and treatments received. These particular features should be taken into account for a population that is highly exposed to SARS-CoV2 contagion due to high number of hospital visits for treatment. Disclosures Hernandez-Rivas: Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees; Rovi: Membership on an entity's Board of Directors or advisory committees. Ocio:MDS: Honoraria; Asofarma: Honoraria; Takeda: Honoraria; GSK: Consultancy; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria; Secura-Bio: Consultancy; Oncopeptides: Consultancy. López Jiménez:Gilead: Research Funding, Speakers Bureau; Janssen: Research Funding, Speakers Bureau; Roche: Research Funding, Speakers Bureau; MSD: Speakers Bureau; Takeda: Speakers Bureau; Abbvie: Research Funding, Speakers Bureau. Córdoba:Takeda Farmacéutica España S.A.: Speakers Bureau; Janssen: Honoraria, Other: travel and accommodation; Abbvie: Honoraria, Other: travel and accommodation; Roche: Honoraria, Other: travel and accommodation; Gilead: Honoraria, Other: travel and accommodation. Moraleda:Takeda: Consultancy, Other: Travel Expenses; Sandoz: Consultancy, Other: Travel Expenses; Novartis: Consultancy, Other: Travel Expenses; Gilead: Consultancy, Other: Travel Expenses; Jazz Pharmaceuticals: Consultancy, Research Funding. Garcia-Sanz:Takeda: Consultancy, Research Funding; Pharmacyclics: Honoraria; Novartis: Honoraria; Janssen: Honoraria, Research Funding; Incyte: Research Funding; Gilead: Honoraria, Research Funding; BMS: Honoraria; Amgen: Membership on an entity's Board of Directors or advisory committees.

Advances in acute myeloid leukemia (AML) genomics and targeted therapies include the recently approved BCL2 inhibitor venetoclax. The association between BCL2 expression and patient outcome was analyzed in a series of 176 consecutive AML patients at diagnosis (Dx), post-induction (PI), complete remission (CR) and relapse (RL). Levels increased significantly at relapse (mean 1.07 PI/0.96 CR vs. 2.17 RL, p = 0.05/p = 0.03). In multivariate analysis, high BCL2-Dx were marginally associated with worse progression-free survival, while high PI levels or at CR had an independent negative impact on outcome (PI: HR 1.58, p = 0.014, CR: HR 1.96, p = 0.008). This behavior of high PI or CR BCL2 levels and increased risk was maintained in a homogeneous patient subgroup of age &lt, 70 and intermediate cytogenetic risk (PI: HR 2.44, p = 0.037, CR: HR 2.71, p = 0.049). Finally, for this subgroup, high BCL2 at relapse indicated worse overall survival (OS, HR 1.15, p = 0.05). In conclusion, high BCL2 levels PI or at CR had an independent negative impact on patient outcome. Therefore, BCL2 expression is a dynamic marker that may be useful during AML patient follow up, and BCL2 levels at PI and/or CR may influence response to anti-BCL2 therapy.

OBJECTIVES: In patients with essential thrombocythemia (ET), after the JAK2V617F driver mutation, mutations in CALR are common (classified as type-1, 52-bp deletion, or type-2, 5-bp insertion). CALR mutations have generally been associated with a lower risk of thrombosis. This study aimed to confirm the impact of CALR mutation type on thrombotic risk. METHODS: We retrospectively investigated 983 ET patients diagnosed in Spanish and Polish hospitals. RESULTS: With 7.5 years median follow-up from diagnosis, 155 patients (15.8%) had one or more thrombotic event. The 5-year thrombosis free survival (TFS) rate was 83.8%, 91.6% and 93.9% for the JAK2V617F, CALR-type 1 and CALR-type 2 groups, respectively (p = 0.002). Comparing CALR-type 1 and CALR-type 2 groups, TFS for venous thrombosis was lower in CALR-type 1 (p = 0.046), with no difference in TFS for arterial thrombosis observed. The cumulative incidence of thrombosis was significantly different comparing JAK2V617F vs. CALR-type 2 groups but not JAK2V617F vs. CALR-type 1 groups. Moreover, CALR-type 2 mutation was a statistically significant protective factor for thrombosis with respect to JAK2V617F in multivariate logistic regression (OR: 0.45, p = 0.04) adjusted by age. CONCLUSIONS: Our results suggest that CALR mutation type has prognostic value for the stratification of thrombotic risk in ET patients.

The development of thrombotic events is common among patients with polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). We studied the influence of pathogenic mutations frequently associated with myeloid malignancies on thrombotic events using next-generation sequencing (NGS) in an initial cohort of 68 patients with myeloproliferative neoplasms (MPN). As expected, the presence of mutations in DNMT3A, TET2, and ASXL1 (DTA genes) was positively associated with age for the whole cohort (p = 0.025, OR: 1.047, 95% CI: 1.006&ndash, 1.090). Also, while not related with events in the whole cohort, DTA mutations were strongly associated with the development of vascular events in PV patients (p = 0.028). To confirm the possible association between the presence of DTA mutation and thrombotic events, we performed a case-control study on 55 age-matched patients with PV (including 12 PV patients from the initial cohort, 25 with event vs. 30 no event). In the age-matched case-control PV cohort, the presence of &ge, 1 DTA mutation significantly increased the risk of a thrombotic event (OR: 6.333, p = 0.0024). Specifically, mutations in TET2 were associated with thrombotic events in the PV case-control cohort (OR: 3.56, 95% CI: 1.15&ndash, 11.83, p = 0.031). Our results suggest that pathogenic DTA mutations, and particularly TET2 mutations, may be an independent risk factor for thrombosis in patients with PV. However, the predictive value of TET2 and DTA mutations in ET and PMF was inconclusive and should be determined in a larger cohort.

BACKGROUND AND OBJECTIVE MYELOFIBROSIS: is an infrequent chronic myeloproliferative neoplasm. We aimed to describe the clinico-biological characteristics, treatment, and evolutive course of myelofibrosis patients in Spain.A total of 1,000 patients from the Spanish Registry of Myelofibrosis diagnosed with primary (n=641) or secondary (n=359) myelofibrosis were analysed.Median age was 68 years. The frequency of constitutional symptoms, moderate to severe anaemia (Hb10g/dL), and symptomatic splenomegaly was 35%, 36%, and 17%, respectively. The rate of thrombosis and haemorrhage was 1.96 and 1.6 events per 100 patient-years, respectively. The cumulative incidence of leukaemia at 10 years was 15%. The most frequent therapies for the anaemia were the erythropoiesis stimulating agents and danazol. From 2010, a progressive increase in the use of ruxolitinib was noticed. A total of 7.5% of patients were transplanted. During the observation period, 42% of patients died mainly due to the clinical deterioration caused by myelofibrosis or leukaemic transformation. The median survival of the series was 5.7 years. Four different risk categories were identified by the IPSS: median survival was not reached in the low risk group and was 8.8 years, 5.3 years, and 2.8 years in the intermediate-1, intermediate-2, and high-risk groups, respectively.Myelofibrosis is a disabling condition mainly affecting elderly people. Its treatment is mostly driven by symptom control. Despite its clinical heterogeneity, several prognostic models are useful to select candidates for transplantation.

Purpose: ENESTfreedom is evaluating treatment-free remission (TFR) following frontline nilotinib in patients with chronic myeloid leukemia (CML) in chronic phase. Following our primary analysis at 48 weeks, we here provide an updated 96-week analysis. Methods: Attempting TFR required ≥ 3 years of nilotinib, a molecular response of MR4.5 [BCR-ABL1 ≤ 0.0032% on the International Scale (BCR-ABL1IS)], and sustained deep molecular response (DMR) during a 1-year consolidation phase. Patients restarted nilotinib following loss of major molecular response (MMR; BCR-ABL1IS ≤ 0.1%). Results: Ninety-six weeks after stopping treatment (3.6-year median prior nilotinib duration), 93 of 190 patients (48.9%) remained in TFR. Of 88 patients who restarted nilotinib following loss of MMR, 87 regained MMR and 81 regained MR4.5 by the data cut-off. Ninety-six-week TFR rates were 61.3, 50.0, and 28.6% in patients with low, intermediate, and high Sokal risk scores at diagnosis, respectively. Patients consistently in MR4.5 during consolidation had higher TFR rates (50.6%) than patients with ≥ 1 assessment without MR4.5 during consolidation (35.0%). In a landmark analysis, 96-week TFR rates for patients with MR4.5, MR4 (BCR-ABL1IS ≤ 0.01%) but not MR4.5, and MMR but not MR4 at TFR week 12 were 82.6, 23.1, and 0%, respectively. There were no reports of disease progression or death due to CML; overall adverse event frequency decreased following TFR. Within the follow-up period, TFR did not adversely affect disease outcomes. Conclusions: These results demonstrate the feasibility and durability of TFR following frontline nilotinib and emphasize the importance of sustained DMR for TFR.

Background: Ruxolitinib is the standard of care for myelofibrosis (MF). However not all patients respond to ruxolitinib and other lose response while on treatment or require discontinuation due to adverse events. Therefore, several clinical trials with ruxolitinib in combination with other drugs are being conducted. We previously showed the synergistic effect of the combination ruxolitinib/nilotinib/prednisone in ex vivo models of peripheral blood mononuclear cells from MF patients and cell lines. Aims: This phase Ib/II study, non-randomized, open-label, evaluates safety and tolerability of ruxolitinib in combination with nilotinib and prednisone in patients with naïve or ruxolitinib-resistant MF. Methods:Between November 2017 and June 2020, 21 patients were included in RUNIC (EudraCT Number:2016-005214-21) at 6 Spanish sites. Six patients were considered screening failures. A total of 15 patients received at least one dose of ruxolitinib and were included in the intention-to-treat (ITT) or the per-protocol (PP) populations. The study design is summarized in figure 1. Out of 15 evaluable patients whose median age was 66.5 years (53.4-70.8). Six patients (40%) had a diagnosis of primary MF, 4 patients (26.7%) post-polycythemia vera MF, and 4 patients (26.7%) post-essential thrombocythemia MF. Most patients had International Prognostic Scoring System (IPSS) intermediate-1 or -2 disease (5 [33.3%] and 4 [26.7%], respectively), and 9 patients (60%) had JAK2 V617F mutation. Most of the patients (n=13; 86.7%) had received ruxolitinib as previous anti-neoplastic therapy for MF. Results:Eight patients completed 7 cycles (53.3%), and six patients 12 cycles (40%) and nine patients withdrawn because of disease progression, lack of efficacy, or no clinical benefit (n=5), withdrawal of consent (n=2), adverse event (AE) (pulmonary thromboembolism, n=1), and investigator's medical judgment (n=1). All patients experienced at least one AE during the study (the most common were hyperglycemia, asthenia and thrombocytopenia, and 14 patients registered at least one treatment-related AE (the most common were hyperglycemia (22.2%), thrombocytopenia (13.3%), and anemia (8.9%)). Five treatment-related serious adverse events (SAEs) were reported in 2 patients (13.3%), all of them related to nilotinib: one patient had pericardial effusion and bilateral pleural effusion, the other had congestive heart failure, pleural effusion, and pulmonary hypertension. No deaths were registered throughout the study.There were 2 patients with at least one adverse event meeting criteria for dose-limiting toxicity: grade 4 anemia and lumbar pain. Only eight patients were evaluated for spleen lengths at screening and cycle 7 (Figure 2B). Of these, 6 experienced a palpable spleen reduction, 4 of them with a 100% reduction. In contrast, one patient remained with the same spleen length, and one patient experienced a 25% increase.Six patients had both symptom evaluation at screening and cycle 7 (Figure 2D). Four experienced a total symptom score reduction, one patient remained with the same total symptom score, and two patients reported an increase.Six patients had spleen length measures recorded both at screening and at cycle 12. From those, 4 showed a spleen length reduction, 3 of them with a 100% reduction. Conclusions: Ruxolitinib in combination with nilotinib and prednisone showed relevant clinical activity in patients with naïve or ruxolitinib-resistant MF. The tolerability of this combination was acceptable, and the hyperglycemia was the treatment-related AE most frequent. The main cause of trial withdrawn was disease progression, lack of efficacy, or no clinical benefit. Based on these results, this triple combination should be explored in phase II/III clinical trials. Figure 1 Figure 1. Disclosures Ayala: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria; Celgene: Honoraria. Garcia Gutierrez: BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Osorio: Janssen, Abbvie, Roche: Consultancy. Sanchez: Janssen, Jazz Pharmaceuticals, Gilead, Novartis, Amgen: Consultancy. Martínez-López: Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy; Roche, Novartis, Incyte, Astellas, BMS: Research Funding.

Introduction: Current recommendations for patients with low-risk polycythemia vera (PV) include hematocrit (Htc) control with phlebotomies and primary prophylaxis of thrombosis with low-dose aspirin. There is scarce information regarding the hematological control, the incidence of complications and the need for cytoreduction in PV patients treated with phlebotomies only. Methods: A total of 358 patients with low-risk PV ( Results: Baseline characteristics at the time of diagnosis are described in Table 1. Table 2 summarizes the main hematological and clinical characteristics under treatment with phlebotomies. Inadequate control of the Htc (> 45%) was reported in 61-70% of the patients, leukocytosis >15x10 9/l in 10% and thrombocytosis >1000x10 9/l in 5%. In addition, about 20% of the patients had pruritus and 10% had microvascular symptoms. Of the 358 patients included, 275 (77%) required cytoreduction, 261 (73%) with hydroxyurea and 14 (4%) with IFN. The main indication of cytoreduction was thrombocytosis (20%), followed by age >60 years old (15%) and microvascular symptoms (13%). Median duration of cytoreduction abstention was 4.7 (0.1-30.4) years being significantly longer in patients younger than 50 years (6 and 2 years for patients younger and older than 50 years, respectively, p With a follow-up of 1659 person-years under phlebotomy only treatment, 14 thrombosis were observed (arterial n=9, venous n= 5), 12 hemorrhages (major n=4, minor n=8) and 4 solid tumors (1 melanoma and 3 non-cutaneous carcinomas). The incidence of complications during the cytoreduction-free period by person-years was: 0.8% for thrombosis, 0.2% for major hemorrhage and 0.2% for second neoplasia. The median follow-up until last visit including the time after starting cytoreductive therapy was 8.4 (0.2-39) years. Of 14 deaths observed, none occurred during the phlebotomy period. Half of the patients died from PV related reasons but the other 50% were not related. The median survival estimation by K-M was 36.5 years. Disease progression was documented in 27 (7.5%) patients, 26 of them to myelofibrosis, 1 to myelodysplastic syndrome and none to acute leukemia. Progression to myelofibrosis occurred during the cytoreduction-free period in 5 patients (1.4%) after a median of 5.8 years (Range: 4.9-8.9). Conclusions The incidence of thrombotic and hemorrhagic complications was very low in this series of low-risk patients treated with phlebotomies, even though only 30-40% of patients maintained the Htc Representing the Spanish Group of Myeloproliferative Disorders. GEMFIN Figure 1 Figure 1. Disclosures Bellosillo: Qiagen: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding; Thermofisher Scientific: Consultancy, Speakers Bureau. Ferrer Marin: Cty: Research Funding; Incyte: Consultancy, Research Funding; Novartis: Speakers Bureau. Garcia Gutierrez: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding.

Introduction: Conventional karyotype analysis is one of the most important diagnostic tools to determine the prognosis of acute myeloid leukemia (AML), in which more than 50% of cases are affected. However, the low sensitivity of this technique hampers the detection of small genetic alterations like Copy Number Variation (CNV) that could affect the pathophysiology and prognosis of the disease. Current modern genomic technologies based on next generation sequencing (NGS) are capable to detect CNV at low frequencies. Objective: To analyse CNV of genes related to myeloid neoplasms profile in AML patients at diagnosis and evaluate their connection with the mutational profile, and its possible influence on the clinical-biological phenotype and prognosis of the disease. Materials and methods: The CNV and mutational profile were analysed in samples from 380 AML patients, from PLATAFO-LMA reference centres (IMIBIC, Córdoba and Dr Negrín Las Palmas de Gran Canaria) by NGS, applying a panel of 30 genes (154 regions) related to myeloid neoplasms (Sophia Myeloid Solution®) on Ilumina Myseq platform. Results: NGS detected CNV in at least one gene in 103 AML patients (27.1%). NGS detected 103 gains and 206 losses of genetic material. The median number of genes affected by CNV was 2 (range 1-12). When comparing with conventional karyotype information, CNV provided additional information in 51% of the cases. The chromosomes 7, 11 and 21 were most affected with CNV, occurring in 79 (76.7%), 40 (38.8%) and 36 (35%) patients, respectively. The gains of genetic material occurred more frequently on chromosome 21 in U2AF1 and RUNX1 genes, in 13 patients each. The loss of genetic material in EZH2 and BRAF genes occurred mutually. Interestingly, we observed the tendency that patients with CNV (loss) in NPM1 gene had shorter overall survival compared to cases with NPM1 mutated and without CNV in this gene (1 month vs. 13 months, p = 0.072) (Figure 1). Moreover CNV (loss) in TP53 gene was associated with mutations in this gene, other than deletions (p In addition, NGS detected 390 mutations distributed in 29 genes in 103 AML with CNV. The median number of mutations was 3 (range 1-10) (Figure 2). Furthermore, only 2 patients did not have any mutation in genes analysed. The distribution and frequency of genes affected by CNV and by mutations was different (Figure 3). Conclusions: The CNV of genes related to myeloid neoplasms are frequent in AML patients (27.1%) and provides additional information to the conventional karyotype in half of the cases. The loss of NPM1 gene could affect survival of AML patients. The use of NGS with CNV analysis provides important information on copy number alterations that are not detected by the karyotype, which could significantly affect the pathophysiology of AML and with potential clinical impact, especially in patients with normal karyotype. Figure 1 Figure 1. Disclosures Hernández Rivas: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees.

Next-Generation Sequencing (NGS) has recently been introduced to efficiently and simultaneously detect genetic variations in acute myeloid leukemia (AML). However, its implementation in the clinical routine raises new challenges focused on the diversity of assays and variant reporting criteria. To overcome this challenge, the PETHEMA group established a nationwide network of 7 reference laboratories aimed to deliver molecular results to the clinics. We report the technical cross-validation results for NGS and clinical validation in 2960 AML samples. Three cross-validation rounds (CVR) were performed to establish consensus parameters for NGS analysis and variant reporting. In the first CVR we evaluated the starting situation of the NGS studies. In the second CVR the laboratory network established minimum quality parameters and consensus recommendations to guarantee a valid NGS assay. The third CVR strengthened the established parameters and refined the clinical variant classification. The clinical validation was performed in 2960 samples from 2703 patients: 1530 male and 1173 female with a median age of 67.5 years old. 2522 samples were collected at diagnosis, 275 at relapse and 163 at refractory AML from October 2017 to October 2019. NGS analysis was performed according to already implemented protocols and only variants accomplishing the established quality control parameters were considered. In the first CVR the error rate (ER) was 39% with a high variability in the studied genes. Then, 30 genes were agreed as key genes for AML pathogenesis: 8 were considered mandatory due to their implication in clinical guidelines, targeted therapy and risk stratification and the study of the remaining 22 was recommended based on panel availability (Table 1). In the second CVR the ER was reduced to 14.4% and the NGS quality metrics were 4032X of mean read depth and 98.3% of median uniformity. Therefore, the laboratory network established a minimum read depth of 500X and uniformity >85% as quality control parameters. Due to the high variability in the detection of low VAF variants (1 CVR: ER 8043 variants were reported in the 2960 samples, with 96.5% of patients showing at least 1 mutated gene. The mean number of variants per sample was 2.71 (range 0-9), the number of mutations in ≥65 years old patients (2.9 vs. 2.5, P At least 1 mutation in one of the 8 clinically relevant genes was detected in the 78.7% of patients: 39.8% of patients had targetable mutations (FLT3-ITD/TKD and IDH1/2 mutations) and 35.6% of patients, variants found in ASXL1, RUNX1 and TP53 were the only clinically relevant variant detected. The study of clonal evolution through paired-sample analysis showed that mutations in FLT3, KRAS, NRAS and PTPN11 were particularly unstable at relapse or refractoriness. We show the development of the first national strategy for validation of NGS studies with centralized analysis in an AML cooperative group. We have developed a laboratory network with standardized protocols to ensure technical quality and equity in access to NGS studies. The unification of analysis and interpretation criteria represents a significant increase in the quality of diagnostic tests and translational research. N/A-NI-AML-PETHEMA-007343, PI18/01340, PI19/00730, FI19/00059 Figure 1 Figure 1. Disclosures Ayala: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria; Celgene: Honoraria. Tormo: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Perez-Simon: JANSSEN, TAKEDA, PFIZER, JAZZ, BMS, AMGEN, GILEAD: Other: honorarium or budget for research projects and/or participation in advisory boards and / or learning activities and / or conferences. Martínez-López: Janssen, BMS, Novartis, Incyte, Roche, GSK, Pfizer: Consultancy; Roche, Novartis, Incyte, Astellas, BMS: Research Funding. Montesinos: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Agios: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Glycomimetics: Consultancy; Tolero Pharmaceutical: Consultancy.

Background: Data from the phase 2, single-arm ENESTfreedom study (NCT01784068) have demonstrated the feasibility of treatment-free remission (TFR) following front-line nilotinib (NIL) treatment, with substantial TFR rates being sustained over time among patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP). Results for long-term outcomes after a 5-year follow-up are presented here. The current subanalysis evaluated the efficacy and safety of TFR after upfront treatment with NIL in older (≥65 years [yrs] at study entry) vs younger ( Methods: Adult pts enrolled in ENESTfreedom had achieved MR4.5 after ≥2 years of front-line treatment with NIL. They then entered a 52-week consolidation (CONS) phase in which they continued treatment with NIL 300 mg twice-daily; pts still in MR4.5 at the end of CONS entered the TFR phase. NIL treatment was re-initiated upon loss of major molecular response (MMR). Rates of MMR and MR4.5, as well as safety, were evaluated according to age group ( Results: The total number of pts analyzed was 215, of which 171 were Disclosures García Gutiérrez: Novartis Pharma AG: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding. Radich:Jazz: Consultancy; Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding. Hochhaus:MSD: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria. Saglio:Roche: Research Funding; Ariad: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding. Conneally:Novartis: Consultancy, Research Funding; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Gilead: Honoraria. le Coutre:Incyte: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Gattermann:Novartis: Honoraria, Research Funding. Saussele:Pfizer: Honoraria; Incyte: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Giles:Actuate Therapeutics Inc: Consultancy; Pfizer: Research Funding; Novartis: Consultancy, Research Funding. Aimone:Novartis: Current Employment. Li:Novartis: Current Employment. Titorenko:Novartis: Current Employment. Ross:Celgene: Research Funding; Bristol-Myers Squibb: Honoraria; Novartis: Honoraria, Other: Participated in advisory board meetings, Research Funding.

With tyrosine kinase inhibitors (TKI), chronic myeloid leukemia (CML) patients are achieving similar rates of survival to the general population and some treatment aspects such as adherence and drug-to-drug interactions (DDI) are becoming increasingly important. Our aim was to investigate the frequency and real clinical consequences of DDI between TKI and concurrent medications in CML. We performed a retrospective multicenter study including 105 patients receiving 134 TKI treatments. Sixty-three patients (60%) had at least one potential DDI. The mean number of concomitant medications was 4.8 (0-19). The mean number of DDI by TKI treatment was 1.2 (0-8); it increased with the number of concomitant medications and age in a significant manner. A total of 159 DDI were detected, involving 55 different drugs. The most common drug classes involved were proton pump inhibitors, statins, and antidepressants. A DDI-related clinical effect (toxicity and/or lack of efficacy) was suspected during the common course of patient follow-up in only five patients (4.7%). This number increased to 20% when data were centrally reviewed. Most of the adverse events (AE) attributed to DDIs were mild. The most common were diarrhea, vomiting, edema, cramps, and transaminitis. Nilotinib and dasatinib showed a tendency towards a higher risk of DDI compared with imatinib. There were no significant differences in AE frequency or in treatment response between patients with or without DDI. Due to their frequency, and their potential to cause clinically relevant effects, DDI are an important aspect of CML management.

Paroxysmal nocturnal hemoglobinuria (PNH) is associated with severe end-organ damage and a high risk of thrombosis. Budd- Chiari syndrome, which develops after thrombotic occlusion of major hepatic blood vessels, is relatively common in PNH and has been associated with increased mortality. We report the case of a 46-year-old male with PNH who presented with Budd-Chiari syndrome associated with portal cavernoma, portal hypertension and hypersplenism. In September 2010, the patient suffered gastrointestinal bleeding, hematuria, and elevated plasma lactate dehydrogenase; he started eculizumab therapy with a good response. In October 2012, he developed upper gastrointestinal variceal bleeding and a splenorenal shunt was placed. At the time of writing, the patient remains stable and eculizumab continues to be effective. There is limited data on the use of eculizumab for prevention of hemolysis and its consequences in PNH patients undergoing surgery. Our findings provide evidence for the efficacy and safety of eculizumab in this setting.

Hematocrit control below 45% is associated with a lower rate of thrombosis in polycythemia vera. In patients receiving hydroxyurea, this target can be achieved with hydroxyurea alone or with the combination of hydroxyurea plus phlebotomies. However, the clinical implications of phlebotomy requirement under hydroxyurea therapy are unknown. The aim of this study was to evaluate the need for additional phlebotomies during the first five years of hydroxyurea therapy in 533 patients with polycythemia vera. Patients requiring 3 or more phlebotomies per year (n=85, 16%) showed a worse hematocrit control than those requiring 2 or less phlebotomies per year (n=448, 84%). There were no significant differences between the two study groups regarding leukocyte and platelet counts. Patients requiring 3 or more phlebotomies per year received significantly higher doses of hydroxyurea than the remaining patients. A significant higher rate of thrombosis was found in patients treated with hydroxyurea plus 3 or more phlebotomies per year compared to hydroxyurea with 0-2 phlebotomies per year (20.5% vs. 5.3% at 3 years; P

Patched homolog 1 gene (PTCH1) expression and the ratio of PTCH1 to Smoothened (SMO) expression have been proposed as prognostic markers of the response of chronic myeloid leukemia (CML) patients to imatinib. We compared these measurements in a realistic cohort of 101 patients with CML in chronic phase (CP) using a simplified qPCR method, and confirmed the prognostic power of each in a competing risk analysis. Gene expression levels were measured in peripheral blood samples at diagnosis. The PTCH1/SMO ratio did not improve PTCH1 prognostic power (area under the receiver operating characteristic curve 0.71 vs. 0.72). In order to reduce the number of genes to be analyzed, PTCH1 was the selected measurement. High and low PTCH1 expression groups had significantly different cumulative incidences of imatinib failure (IF), which was defined as discontinuation of imatinib due to lack of efficacy (5% vs. 25% at 4 years, P = 0.013), probabilities of achieving a major molecular response (81% vs. 53% at first year, P = 0.02), and proportions of early molecular failure (14% vs. 43%, P = 0.015). Every progression to an advanced phase (n = 3) and CML-related death (n = 2) occurred in the low PTCH1 group (P

Introduction The clinical characteristics, treatment, cardiovascular events (CVE) and evolution of patients diagnosed with JAK2 V617F positive essential thrombocythemia (ET) with low allele burden (LAB) are scarcely studied. Its presence in people without a confirmed diagnosis of malignant hemopathy is called clonal hematopoiesis of uncertain significance (CHIP) and confers higher risk of developing CVE. The objective of this study was to compare the clinical characteristics and CVE of a series of JAK2 V617F-positive ET patients with Methods From the database of the GEMFIN group, 410 ET patients were JAK2 V617F positive, 89 (21.7 %) with LAB and 321 (78.3%) with HAB. The clinical characteristics, treatment (cytoreduction, antiagregation, anticoagulation, JAK inhibitor), CVE (before, at and after diagnosis) and evolution to myelofibrosis (MF) or acute myeloid leukemia (AML) of these two groups of patients were compared. Results LAB and HAB groups did not significantly differ regarding the main clinical characteristics (i.e cardiovascular risk factors [CVRF] and International Prognostic Score for Thrombosis in Essential Thrombocythemia [IPSET] score) except for the median platelet count: LAB 636 x109/L [436- 2500] vs HAB 687 x109/L[440-1980L], p=0.035). CVE after diagnosis of ET were more frequent in patients with HAB (41/137, 30%) than in patients with LAB (5/48, 10%), p=0.007. Only one LAB patient with CVE had JAK2 allele burden >5%. Treatments received by both groups were not significantly different. None of the patients from both groups progressed to AML, whereas 1/48 vs. 6/137 of patients evolved to MF. Median follow-up of patients with LAB and HAB was 3.4 years [0.1-17.7] and 4.3 years [0.1-27.8], respectively (Table 1). Conclusions In these series of ET patients from the GEMFIN group, patients with LAB had significantly lower median platelet count at diagnosis and less CVE after diagnosis than patients with HAB, although CVRF and IPSET scores and treatment approach were similar. The clinical behavior of LAB patients may resemble that of individuals with CHIP. The therapeutic algorithm of ET patients with LAB may be somehow different than that of patients with HAB and therefore, might be revised. Disclosures Bellosillo: Astra-Zeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees; Biocartis: Honoraria; Merck-Serono: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Qiagen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Hoffman â€"La Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; ThermoFisher: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; BMS: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid. Pérez:Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Study Rationale The present study with ponatinib is based on previous studies on the potential role of imatinib discontinuation, to achieve a stable treatment-free remission (TFR) of patients with Philadelphia-positive Chronic Myeloid Leukemia (CML). As ponatinib has shown to induce deeper molecular responses compared with imatinib, the rationale is that ponatinib treatment could increase the proportion of patients who could discontinue treatment successfully. Purpose The purpose is to determine the successful TFR within the first 48 weeks following cessation of treatment in patients who achieved MR4 on imatinib, and maintained MR4 on ponatinib, after a switch from imatinib. Eligible patients have been previously treated with imatinib as unique tyrosine kinase inhibitor (TKI) therapy, for at least 4 years, and have documented MR4 (at least 12 months) at the time of ponatinib to study entry. Objectives The Primary Objective is to evaluate the proportion of patients without confirmed loss of MR4 or loss of MMR (do not require confirmation). The Key Secondary Objectives are: To evaluate the proportion of patients without confirmed loss of MR4 or loss of MMR within 72 and 96 weeks following ponatinib cessation.To estimate progression-free survival (PFS) from the date of ponatinib cessation to the date of the earliest event. Treatment-free survival (TFS) defined as a lack of any of the following: loss of MMR, confirmed loss of MR4, re-start of imatinib treatment, progression of AP/BP, or death from any cause.Overall survival (OS), defined as the time from the date of cessation of ponatinib therapy to the date of death from any cause.Proportion of patients who regain MR4 within 48 weeks of imatinib treatment re-initiation, following confirmed loss of MR4 within 48 weeks subsequent to ponatinib cessation.Kinetics of BCR-ABL transcript level (IS) after re-start of imatinib therapy. Other Secondary Objectives include adverse events, laboratory data for hematology, biochemistry, and urinary test, vital signs and ECGs. Exploratory Objectives include phenotypic and genotypic biomarkers, as well as functional analysis of cytotoxic cell activation. Plasma monitoring of ponatinib levels will also be performed. Study Design This is a single-arm, open label study, open label study in 40 patients who achieved and maintained MR4, to determine the rate of successful TFR in both gender patients, treated with 15 mg/day of ponatinb for 48 weeks. Ten Spanish sites will participate. The study has two main phases: ponatinib consolidation (48 weeks) and ponatinib TFR phase (96 weeks). Inclusion criteria are patients who had received a minimum of 4 years imatinib as unique TKI therapy, have documented MR4 at least 12 months prior to study entry, and will continue with MR4 before the discontinuation of ponatinib. After stopping ponatinb (TFR phase), BCR-ABL wil be monitored every 4 weeks during the first 48 weeks, and every 12 weeks during the last period of 48 weeks. Exclusion criteria include patients with transplant, atypical transcripts, CML treatment resistant mutation, or having cardiovascular or pancreatitis diseases. Figure 1: Current State of the Study First Visit First Patient: 17 JUL 2019 Patients Enrolled: 4 Patients Recruited: 3 Screening Failure: 0 In Screening: 1 patient Figure 1 Disclosures Sanchez-Guijo: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Honoraria; Roche: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid. Steegmann:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.