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Torque Teno Virus (TTV) is a single-stranded circular DNA virus which has been identified as a surrogate marker of immune competence in transplantation. In this study we investigated the dynamics of plasma TTV DNAemia in 79 adult patients undergoing chimeric antigen receptor T-cell (CAR-T) therapy for relapsed or refractory large B-cell lymphoma, also evaluating the impact of TTV on immunotoxicities, response and survival outcomes. After lymphodepleting therapy, TTV DNA load decreases slightly until reaching nadir around day 10, after which it increased steadily until reaching maximum load around day 90. TTV DNA load

To develop a prognostic model for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) for myelofibrosis (MF). We examined 623 patients undergoing allo-HCT between 2000 - 2016 in the USA (CIBMTR cohort). A Cox multivariable model was used to identify factors prognostic of mortality. A weighted score using these factors was assigned to patients transplanted in Europe (EBMT cohort) (n = 623). Age above 50 (hazard ratio [HR], 1.39; 95% confidence interval [CI], 0.98 -1.96), and HLA matched unrelated donor (HR, 1.29; 95% CI, 0.98-1.7) were associated with increased hazard of death and were assigned 1 point. Hemoglobin lower than 100g/L at time of transplant (HR, 1.63; 95% CI, 1.2- 2.19), and a mismatched unrelated donor (HR, 1.78; 95% CI, 1.25- 2.52), were assigned 2 points. The 3-year overall survival (OS) in patients with a low (1-2 points), intermediate (3-4 points) and high score (5 points) were 69% (95% CI, 61% -76 %), 51 % (95% CI, 46% -56.4 %), and 34% (95% CI, 21% - 49%), respectively (P. < 0.001). Increasing score was predictive of increased transplant related mortality (TRM) (P .0017) but not for relapse (P. 0.12). The derived score was predictive for OS (P. < 0.001) and TRM (P. 0.002) but not relapse (P. 17) in the EBMT cohort as well. The proposed system was prognostic of survival in two large cohorts, CIBMTR and EBMT, and can easily be applied by clinicians consulting patients with MF on transplant outcomes.

To date, five tyrosine kinase inhibitors (TKIs) are available for treating chronic myeloid leukemia (CML) patients in clinical practice. Despite this, a significant proportion of patients will ultimately develop failure to approved TKIs due to intolerance or resistance. Consequently, new treatment approaches are still required in this unmet clinical need. Asciminib, a first-in-class BCR::ABL1 inhibitor Specifically Targeting the ABL Myristoyl Pocket (STAMP), has the potential to overcome resistance/intolerance to prior TKI treatment.This review will cover the mechanism of action, pharmacokinetic profile, and clinical data of asciminib based on available information from laboratory studies, clinical trials, and real-world evidence.Recent approval of asciminib will require positioning of this drug in the treatment algorithm of CML patients failing initial TKI therapy. Available data support the lack of cross-intolerance of asciminib with other TKIs and its favorable cardiovascular toxicity profile. In addition, asciminib has demonstrated considerable efficacy in CML patients who have failed at least two TKIs, although preliminary data suggest that this efficacy may be lower in those previously exposed to ponatinib. The introduction of asciminib in clinical practice may represent an important step forward in the management of CML.

During the Editorial process, the author name of Juan Carlos Hernández-Boluda to Hernández Boluda. The original article was updated to correct this. Korrektur zu: 10.1038/s41375-021-01294-2

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.

Objective To compare the efficacy and safety of CD34+ selected ex vivo T-cell depletion (TCD) vs post-transplant cyclophosphamide, sirolimus, and mycophenolate mofetil (PTCy-Sir-MMF) as graft-vs-host disease (GVHD) prophylaxis. Methods We retrospectively included patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) with either TCD (n = 38) or PTCy-Sir-MMF (n = 91). Results Cumulative incidence of neutrophil and platelet recovery was 92% vs 99% (P = .06) and 89% vs 97% (P = .3) in TCD and PTCy-Sir-MMF, respectively. Cumulative incidences of aGHVD grade II-IV, III-IV, and moderate to severe cGVHD were 11% vs 19% (P = .2), 3% vs 2% (P = .9), and 3% vs 36% (P < .001) in TCD and PTCy-Sir-MMF, respectively. The 2-year non-relapse mortality, relapse, disease-free and overall survival were 25% vs 8% (P = .01), 20% vs 16% (P = .2), 55% vs 76% (P = .004), 57% vs 83% (P = .004) for TCD and PTCy-Sir-MMF, respectively. Cumulative incidence of cytomegalovirus and Epstein-Barr infection requiring therapy was 76% vs 40% (P < .001) and 32% vs 0% (P < .001) in TCD and PTCy-Sir-MMF, respectively. PTCy-Sir-MMF platform showed faster T-cell reconstitution. Conclusions PTCy-Sir-MMF provides better survival outcomes but is associated with higher risk of cGVHD compared to TCD.

Myeloproliferative Neoplasm (MPN), unclassifiable (MPN-U) is a heterogeneous disease with regards to both clinical phenotype and disease course. Patients may initially be asymptomatic or present with leucocytosis or thrombocytosis, anaemia, progressive splenomegaly, constitutional symptom, thromboses or accelerated/blastic phase disease. Treatment strategies are variable and there are no widely accepted consensus management guidelines for MNU-U. Allogeneic Haematopoietic Cell Transplantation (allo-HCT) remains the only curative strategy yet outcomes, to date, are not well defined. We hereby report on the largest retrospective study of patients with MPN-U undergoing allo-HCT, highlighting the potentially curative role and providing clinicians with robust engraftment, GvHD and outcome data to facilitate patient discussion.

AimTo characterise the clinical and histological features of MPL-mutated essential thrombocythaemia (ET).Patients and methodsBone marrow biopsies of 175 patients with ET were centrally reviewed according to the 2016 WHO classification, including 42 cases with MPL mutation, 98 JAK2V617F-mutated and 35 CALR-mutated. Clinical and histological features were compared among the three genotypes included in the current 2016 WHO classification and among the different types of MPL mutations.ResultsPatients with MPL-mutated ET were significantly older than those with the other genotypes. Haematological values at diagnosis were similar among MPL-mutated and CALR-mutated ET, with both genotypes showing higher platelet counts and lower haemoglobin values than ET with JAK2V617F genotype. In the bone marrow, the median number of megakaryocytes was higher in MPL and CALR than in JAK2V617F genotype (16, 19 and 14 megakaryocytes per ×20 power field, respectively, p=0.004). Histological features of prefibrotic myelofibrosis were rarely observed in MPL genotype, whereas sinusoidal hyperplasia, dense clusters of megakaryocytes and reticulin fibrosis were more frequent in CALR-mutated ET, with 11% of such cases fulfilling WHO 2016 histological criteria of prefibrotic myelofibrosis. With a median follow-up of 3.5 years, no significant differences were seen among genotypes regarding survival, vascular complications or myelofibrotic transformation. There were no significant differences in the clinical data or in the histological characteristics depending on the type of MPL mutation.ConclusionMPL and CALR ET genotypes share clinical and histological characteristics. In contrast to CALR genotype, features of prefibrotic myelofibrosis are uncommon in MPL-mutated ET.

Introduction. MPN-COVID is a European LeukemiaNet cohort study, launched in March 2020 in patients with myeloproliferative neoplasms (MPN) with COVID-19. The first cohort of 175 cases was analyzed at the end of first wave (July 2020) and results provided estimates and risk factors of overall mortality (Barbui T. Leukemia, 2021), thrombosis incidence (Barbui T. Blood Cancer J, 2021), and post-COVID outcomes (Barbui T. Blood Cancer J, 2021). In the second wave of pandemic (June 2020 to June 2021), case-fatality risk in the general population has been found variable across different countries, and no information is available in MPN patients with COVID-19 diagnosed during the second wave in comparison with those of the first wave. Methods. In an electronic case report form, we registered a total of 479 cases of ET (n=161, 34%), PV (n=135, 28%), pre-PMF (n=49, 10%) and overt MF (n=134, 28%), from 39 European hematology units (Italy, Spain, Germany, France, UK, Poland, Croatia). Of these, 304 were diagnosed COVID-19 during the second wave. Results. Patients in the second wave were significantly different from those in the first wave, including parameters such as age (median: 63 vs. 71 years, p Conclusions. This is the largest series of MPN patients who incurred COVID-19 from June 2020 onward, namely during the "second COVID-19 wave". Compared to the first wave, the second one recorded a lower overall COVID-19 severity, but Ruxolitinib discontinuation still remained a risk factor for a dismal outcome. Greater vulnerability of ET than PV in developing venous thrombosis was confirmed also during the second wave. This finding suggests that ET warrants a specific antithrombotic prophylaxis in addition to heparin. Figure 1 Figure 1. Disclosures Barbui: AOP Orphan: 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. Iurlo: Novartis: Speakers Bureau; Incyte: Speakers Bureau; Pfizer: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Sobas: Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Fox: Novartis: Honoraria; Sierra: Honoraria. Palandri: AOP: Membership on an entity's Board of Directors or advisory committees; CTI: Consultancy; Sierra Oncology: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Benevolo: Novartis: 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; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Amgen: Speakers Bureau. Harrison: Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sierra Oncology: Honoraria; Galacteo: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Promedior: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shire: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte Corporation: Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Keros: 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, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Geron: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AOP Orphan Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Constellation Pharmaceuticals: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Bonifacio: Pfizer: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Kiladjian: Taiho Oncology, Inc.: Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Other: Personal fees; AOP Orphan: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Patriarca: Incyte: Honoraria; Takeda: Honoraria; Argenix: Honoraria; Novartis: Honoraria; Amgen: Honoraria; Pfizer: Honoraria. Griesshammer: Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; AOP Orphan: Consultancy, Honoraria; CTI: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Astra Zeneca: Consultancy, Honoraria. Garcia Gutierrez: Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Osorio: Janssen, Abbvie, Roche: Consultancy. Koschmieder: CTI: Membership on an entity's Board of Directors or advisory committees, Other; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support); Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Baxalta: Membership on an entity's Board of Directors or advisory committees, Other; Abbvie: Other: Travel support; Alexion: Other: Travel support; Karthos: Other: Travel support; Sanofi: Membership on an entity's Board of Directors or advisory committees, Other: Travel support; Image Biosciences: Other: Travel support; AOP Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support), Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support); Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support); Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support), Research Funding; Geron: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support), Research Funding; Roche: 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, Other: Travel support, Research Funding; Ariad: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support); Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: (e.g. travel support); Shire: Honoraria, Other. Vannucchi: Incyte: 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; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees.

Background There is a lack of clinical information regarding the usefulness of plasma Epstein-Barr virus (EBV) DNA load kinetics analyses in the management of EBV infections in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Namely, it remains unknown whether this type of analysis can help physicians to anticipate the development of high-level EBV DNAemia episodes requiring rituximab treatment or predict the risk of recurrent EBV DNAemia or post-transplant lymphoproliferative disorders (PTLDs). Study design Unicentric, retrospective, observational study including 142 consecutive patients undergoing T-cell replete allo-HSCT. The plasma EBV DNA load was monitored on a weekly basis using the artus® EBV PCR kit. Results Fifty-five of the 142 patients (38.7%) developed at least one episode of EBV DNAemia; 13 of the 55 initial EBV DNAemia episodes (23.6%) were preemptively treated with rituximab, 7 patients had a recurrent episode of EBV DNAemia, and biopsy-proven PTLDs were diagnosed in 4 patients. The initial plasma EBV DNA load was not significantly different (P = 0.269) in episodes of self-resolving EBV DNAemia, those requiring rituximab treatment, or those leading to PTLDs. The plasma EBV DNA load doubling times were similar across all the groups (P = 0.799), and the EBV DNA-load half-life was not associated with the occurrence of recurrent EBV DNAemia (P = 0.550). Conclusion Plasma EBV DNA-load kinetics analyses are unlikely to be useful in predicting the occurrence of high-level EBV DNAemia, PTLD, or recurrent EBV DNAemia.

Introduction: Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) are the two autologous anti-CD19 chimeric antigen receptors T cells commercially approved in Europe for relapsed/refractory (R/R) DLBCL. We performed a retrospective study to evaluate patients characteristics, efficacy and safety for axi-cel and tisa-cel in a large cohort of patients within the GETH-TC (Spanish Group of Stem Transplantation and Cell Therapy)-GELTAMO (Spanish Group of Lymphoma and Autologous Stem Cell Transplantation). Methods: Ten Spanish centers contributed data. Data were collected retrospectively from consecutive patients with DLBCL in whom apheresis was performed for axi-cel or tisa-cel treatment. CRS and ICANS were graded with the ASTCT consensus criteria. Response was assessed according to the Lugano criteria. Patients included had at least 30 days of follow-up. Results: A total of 268 patients with R/R DLBCL underwent apheresis for axi-cel (n=123) and tisacel (n=145) from Nov-2018 to May-2021, of which 232 (86%) received CART-cell infusion (n=110, 89% and n=122, 84%, respectively). Reasons for not undergoing infusion were progression in 10 cases, tumor lysis syndrome in 1, infection in 1, and CR after bridging therapy in 1 for the axi-cel cohort, and progression in 21 (4 after manufacture failure), psychiatric disorder in 1, and post-apheresis cerebral hemorrhage in 1 case for the tisa-cel cohort. Time between apheresis and infusion was 41 days (IQR 40-56) and 49 days (IQR 46-62) (p=0.006), respectively. Characteristics at baseline, apheresis and at lymphodepletion are summarized in Tables 1 and 2. Median age was 60 (range 19-79), 61% of patients were male, most of them treated for DLBCL NOS (66%). There were no significant differences between patients intended to be treated with axi-cel and tisa-cel. 82% of the infused patients received bridging therapy. At apheresis and at lymphodepletion ECOG performance status score was 0-1 in 93% and 91%, and 7 and 32 patients were in response, respectively. The overall response rates (ORRs) at 1 month and 3 months were 65% and 56%, respectively, with 34% and 45% achieving a complete response (CR), respectively. In the intention-to-treat analysis, with a median follow-up of 9 months (IQR 5-15), EFS and OS at 9 months was 44% (95%CI 38-51)(Figure 1) and 59% (95%CI 53-66) with a median EFS and OS of 6 months and 11 months, respectively. At lymphodepletion, characteristics of infused patients and disease were not significantly different between axi-cel and tisa-cel cohorts. Rates of CRS, CRS grade 3-4, ICANS, ICANS grade 3-4 were 89% and 71% (p=0.001), 10% and 7% (p=0.34), 42% and 16% (p=0.001), 20% and 4% (p=0.001) for the axi-cel and tisa-cel cohorts, respectively. ICU admission was needed in 25% and 15% of patients (p=0.06), respectively. Non-relapse mortality at days 100 were 2.5% and 1.4%, and at day 180, 5.4% and 2.2% (p=0.08) for the axi-cel and tisa-cel groups, respectively. With a median follow-up of 8 months for patients who received infusion with axi-cel and 12 months for patients infused with tisa-cel, EFS and OS at 12 months were 48% and 33% (p=0.33), and 53% and 50% (p=0.27), respectively, with a median EFS of 11 and 6 months and a median OS of 13 and 12 months, respectively. In the multivariate analysis, the only factor associated with poor PFS was having ECOG-PS ≥2 at lymphodepletion (HR13, p=0.03). No factors were identified as associated independently to OS. Factors associated to CRS grade 3-4 were IPI score 4-5 at lymphodepletion (OR 1.4, p=0.03) and ECOG-PS ≥2 at apheresis (OR 1.5, p=0.03). For ICANS grade 3-4, factors associated were the use of axi-cel (OR 8, p=0.04) and diagnosis of HG double/triple hit lymphoma (OR 9, p=0.022). Conclusions:This multicentric analysis describes one of the largest real-life cohorts of patients treated with axi-cel and tisa-cel for R/R aggressive B cell lymphoma in Europe. Results are comparable to those from the pivotal studies and other large real-life experiences. Up to now, patients included for one or other product in Spain do not differ significantly in terms of baseline characteristics, and within this setting, results are comparable between both products in terms of efficacy. The use of axi-cel was associated to higher rates of CRS and especially, severe forms of ICANS. However, mortality associated to toxicity were low and not significantly different between both cohorts. Figure 1 Figure 1. Disclosures Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria. Iacoboni: BMS/Celgene, Gilead, Novartis, Janssen, Roche: Honoraria. Reguera: Janssen, Kite/Gilead, Novartis: Speakers Bureau; BMS-Celgene, Novartis: Membership on an entity's Board of Directors or advisory committees. Lopez Corral: Gilead, Novartis: Consultancy, Honoraria. Guerreiro: Novartis, Gilead: Consultancy, Honoraria. Caballero: Novartis, Gilead: Honoraria. Ortiz-Maldonado: Kite, Novartis, BMS, Janssen: Honoraria. Sanchez: Janssen, Jazz Pharmaceuticals, Gilead, Novartis, Amgen: Consultancy. Sancho: Roche, Janssen, Celgene-BMS, Gilead, Novartis, Takeda: Honoraria, Speakers Bureau; Roche, Janssen, Celgene-BMS, Gilead, Novartis, Incyte, Beigene: Speakers Bureau. Bastos-Oreiro: Janssen: Honoraria, Speakers Bureau; F. Hoffmann-La Roche: Honoraria, Research Funding, Speakers Bureau; Takeda: Speakers Bureau; Novartis: Honoraria, Speakers Bureau; BMS-Celgene: Honoraria, Speakers Bureau; Gilead: Honoraria; Kite: Speakers Bureau. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Mussetti: Gilead: Other: Unspecified, Research Funding; Novartis: Honoraria, Other: Unspecified; Takeda: Honoraria. Bailen: Gilead, Pfizer: Speakers Bureau. Martin Garcia-Sancho: Takeda: Honoraria; Novartis: Consultancy; Incyte: Consultancy; Celgene/BMS: Consultancy; Celgene: Honoraria, Other: travel; Roche: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Janssen: Honoraria, Research Funding; Servier: Consultancy, Honoraria, Other: Travel/Accommodations/Expenses; Gilead: Consultancy, Honoraria; Morphosys: Consultancy; Kyowa Kirin: Consultancy; Clinigen: Consultancy; Eusa Pharma: Consultancy; Kern Pharma: Other: TRAVEL, ACCOMMODATIONS, EXPENSES (paid by any for-profit health care company). Barba: Amgen, Celgene, Gilead, Incyte, Jazz Pharmaceuticals, MSD, Novartis, Pfizer and Roche, Jazz Phar,aceuticals: Honoraria; Cqrlos III heqlth Institute, aSOCIACION espanola contra el cancer, PERIS: Research Funding.

Introduction: asciminib is a first-in-class STAMP (Specifically Targeting the ABL Myristoyl Pocket) inhibitor that potently inhibits aberrant kinase activity of the BCR-ABL1 oncoprotein via allosteric binding. asciminib has shown high efficacy profile in heavily pretreated Chronic Myeloid Leukemia (CML) patients with an adequate safety profile in phase I and III clinical trials. However, data from the use of asciminib in real life setting are still scarce. Methods: We gathered real-life retrospective data from 49 patients with BCR-ABL1 positive CML treated with asciminib (mean dose: 40 mg twice daily) between October 2018 and July 2021 at 33 institutions. The indication of asciminib was made according to the criterion of the attending physician and the drug was granted by Novartis under a controlled access program. Molecular biology tests were performed according to ELN guidelines and BCR-ABL/ABL ratios were expressed as % IS in all centers. Treatment responses were calculated with the patients at risk at each specific time points. For the event free survival (EFS), the events were treatment discontinuation due to any reason, progression or death. Data collection followed the local regulations for observational studies. Results: Median time on asciminib was 11,69 months for the entire cohort. Patients' characteristics are displayed on Table 1. Most patients were heavily pretreated with at least 3 prior TKI lines in 45 patients (91,83%), 18 of them receiving prior Ponatinib. Switch to asciminib occurred due to intolerance in 32 patients and due to resistance in the remaining 17. Fifteen patients (30,61%) harbored mutations in BCR-ABL1 (3 with a T315 mutation). Regarding efficacy (Table 2), probability of reaching or maintaining previous responses were 94%, 45% and 21% for complete hematological response (CHR), complete cytogenetic response (CCyR) and major molecular response (MMR), respectively. Considering probabilities of improving previous response, rates were 40%, 42% and 33% for the same parameters. Probabilities to obtain CCyR and MMR in resistant and intolerant patients were 29% (4/14) vs 55% (6/11) and 27% (4/15) vs 52% (11/21), respectively. Amid the patients previously treated with Ponatinib, probabilities of reaching or maintaining previous response were 53% (9/17) and 35% (6/17) for CCyR and MMR respectively, and 30% (3/10), 23% (3/13) displayed improvement of response. Regarding responses in patients with mutations, 39% (5/13) achieved or maintained CCyR and 31% (4/13) MMR; whereas 20% (2/10) and 18% (2/11) improved such responses. Of the three patients with T315I mutation, one discontinued due to progression to advanced stages, and the rest maintained the previous response. With a median follow-up of 11,69 months, the estimated EFS was 80% (figure 1). In terms of safety (Table 3), the most frequent extra-hematological adverse events (AE) were: fatigue (16,2%), joint pain (13,5%) and nausea (8,1%), most of them grade 1-2. Grade 3-4 AE were observed in 10% of patient (fatigue (2), cholestasis enzyme elevation (1), hypertension (1), pancreatitis (1) and pericardial effusion (1)). Thrombocytopenia was shown as the most frequent AE (16,3%), with 6% of patients suffering from grade 3-4. Dose reduction was required in 15 patients (30,6%). After a median follow up of 51 weeks, 73,5% of the patients remained on treatment. Only fourteen patients discontinued treatment due to progression or loss of efficacy, whereas 6% of patients discontinuing treatment due to intolerance. Conclusions: The results presented are in line with the data obtained in clinical trials, positioning asciminib as a potential safe and efficacious treatment for CML patients with failure to several TKI lines. Figure 1 Figure 1. Disclosures Sanchez-Guijo: Novartis: Consultancy, Honoraria, Research Funding; Celgene/Bristol-Myers-Squibb,: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Takeda: Honoraria, Research Funding; Roche: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Garcia Gutierrez: BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, 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.

Aim: Dynamic assessment of trends over time in patient- and transplant-specific characteristics and outcomes for patients undergoing 1st allogeneic haematopoietic cell transplant (allo-HCT) for Myelofibrosis (MF). Methods and Results: A total of 4142 MF patients were analysed who underwent allo-HCT between 1995-2018 (24-year period) across 278 centres based on data reported to the European Society for Blood and Marrow Transplantation. For analysis, 4 cohorts were considered based on year of allo-HCT: 60 years accounted for 8.7% of adults undergoing allo-HCT whereas for 2015-2018 this was 47%. Over time, increasing number of patients with a Karnofsky performance status (KPS) Conclusions: Despite a marked increase over this 24-year period in recipient age, RIC regimen utilisation and use of both URD and MMRD, this comprehensive analysis demonstrates stable OS and EFS rates. However, rates of GVHD have decreased over time, in particular extensive cGVHD. Further work is required to improve both the considerable NRM and relapse rates which remain significant. Disclosures McLornan: JAZZ PHARMA: Honoraria, Speakers Bureau; CELGENE: Honoraria, Speakers Bureau; NOVARTIS: Honoraria, Speakers Bureau. Platzbecker:Amgen: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Geron: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding. Chevallier:Incyte Corporation: Honoraria. Martínez-Lopez:Altum, Hosea: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Vivia Biotech: Honoraria; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Roche: Speakers Bureau; Janssen: Speakers Bureau; Incyte: Research Funding, Speakers Bureau; Bristol Myers Squibb: Research Funding, Speakers Bureau; Novartis: Research Funding. Yakoub-Agha:Celgene: Honoraria; Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria; Gilead/Kite: Honoraria, Other: travel support; Janssen: Honoraria.

Summary Pathogenic interactions between bacteria and cytomegalovirus (CMV) may potentially occur early after allogeneic stem cell transplantation (Allo-SCT). This possibility nevertheless has not been investigated in depth. This was a retrospective study that included 170 consecutive patients who underwent 173 Allo-SCTs. Both bacterial infection (most of which were bacteremic) and CMV DNAemia were detected in 78 Allo-SCTs (62.9%). In total, 51 and 32 episodes of bacterial infection preceded or occurred after CMV DNAemia detection, respectively. Both events were diagnosed concurrently in four Allo-SCTs. The cumulative incidence of bacterial infection (of any type) over the study period was comparable in patients with or without a preceding episode of CMV DNAemia (P=0.321). Cox proportional hazards regression analysis failed to identify CMV DNAemia as a significant risk factor for bacterial infection. Likewise, the cumulative incidence CMV DNAemia within the study period was not significantly different in patients with or without a preceding episode of bacterial infection (P=0.189). Furthermore, the occurrence of bacterial infection within episodes of active CMV infection had no apparent impact on the kinetics of CMV DNAemia. Our data, thus, do not support the existence of a bidirectional synergistic effect between bacterial infection and active CMV infection in the Allo-SCT setting. This article is protected by copyright. All rights reserved.

Resumen La inhibicion farmacologica de la actividad cinasa de las proteinas JAK permite interferir la senalizacion de las citocinas inmunomoduladoras y bloquear la activacion constitutiva de la via JAK-STAT que caracteriza a ciertas neoplasias, en particular a las mieloproliferativas cronicas. Asi, los inhibidores de JAK pueden ser utiles tanto para el tratamiento del cancer como para el de enfermedades de origen inflamatorio o inmunitario. Hasta el momento, los avances mas significativos se han dado en la mielofibrosis, donde permiten un mejor control de las manifestaciones hiperproliferativas, si bien no parecen tener capacidad de erradicar la enfermedad. En general, la inhibicion de JAK2 se asocia al desarrollo de citopenias, siendo este un efecto adverso de clase. En cambio, el perfil de toxicidad extrahematologica varia de un inhibidor a otro. Actualmente, se estan explorando combinaciones de ruxolitinib con otros farmacos cara a potenciar la eficacia terapeutica y a reducir su toxicidad hematologica.

Torque teno virus (TTV) plasma DNA load has been consistently shown to be a surrogate biomarker of immunosuppression in solid organ transplant recipients. It is uncertain whether it may behave similarly in allogeneic hematopoietic stem cell transplant recipients (allo-HSCT). Here, we characterized the dynamics of TTV DNAemia in patients undergoing T-cell replete allo-SCT at late times after transplantation (> day + 100). This retrospective single-center observational study included 33 allo-HSCT patients. Plasma TTV DNA loads were quantified by real-time PCR before initiating the conditioning regimen and at different time points after transplant. Absolute lymphocyte counts (ALC) were measured by flow cytometry. Overall, TTV DNA load increased steadily after engraftment, reaching a peak by day + 90; afterwards, it remained relatively constant until day + 210. TTV DNA loads measured within days + 120 and + 210 correlated inversely with paired ALC, while both parameters did correlate directly within days + 20 and + 60. The median TTV DNA area under a curve between days + 90 and + 210 [(AUC)90–210] was significantly higher in patients who received corticosteroids within this time frame for treatment of graft versus host disease (either acute, chronic or both) than in controls (P = 0.025). In summary, TTV DNA load may mirror the degree of immunosuppression at late times after allo-HSCT.

Different studies have attempted to identify the best strategy to prevent GvHD1, 2, 3, 4, 5, 6, 7 without hampering GvL. We previously compared the combination of sirolimus (SRL) plus tacrolimus (TKR) with Cyclosporine and mofetil mycophenolate in the setting of unrelated donor (UD) reduced intensity conditioning (RIC),3 and found significantly better outcomes for SRL/TKR in terms of chronic GvHD (55 vs 88%), non-relapse mortality (NRM) (18 vs 38% at 2 years) and overall survival (OS) (72 vs 44%). With this background the use of SRL/TKR has been widespread for alloRIC, regardless of donor type.

Introduction : Azacitidine (AZA) is a DNA hypomethylating agent used in myeloid neoplasms, however approximately half of patients show treatment failure or relapse. Last years, several studies have showed that genetic mutations may influence on response and survival of the treated patients. Other biomarkers that have traditionally been associated with the response to AZA are the recovery of the platelet count and the presence of abnormalities in the chromosome 7. Finally, the methylation dynamics of genes promoters could be a useful tool to predict the clinical response. Aim: To assess the predictive value on response to AZA of clinical features, cytogenetics, genetic mutations and the methylation dynamics of CDKN2B and DLC-1 promoters in a series of patients with myeloid neoplasms. Methods: We studied 85 patients with myelodysplastic syndromes (MDS) and 28 patients with acute myeloid leukemia (AML) who received AZA. Treatment schedules included 5-azacytidine 75 mg/m2/day for 7 days (n=62) and 5-azacytidine 75 mg/m2/day for 5 days (n=51). According to the International Working Group (IWG) 2006 criteria for MDS, responders were defined as patients achieving complete remission (CR), bone marrow CR (mCR), partial remission (PR) or stable disease with hematologic improvement (SDHI). Sixteen genes with prior implication in the pathogenesis of myeloid diseases were analyzed: NPM1, FLT3, CEBPA, TET2, DNMT3A, IDH1, IDH2, ASXL1, EZH2, RUNX1, SETBP1, TP53, SF3B1, SRSF2, U2AF1 and ETNK1. For methylation assay, EZ DNA Methylation-Gold kit (Zymo Research) was employed for the bisulfite treatment of DNA. Methylation of CDKN2B and DLC-1 were qualitatively studied pre- and post-AZA with unmethylated and methylated primers and analysis of the PCR products in a QIAxcel System (Qiagen). Overall survival (OS) was measured from start of AZA treatment until the last follow-up or death from any cause. P values Results: Of the 113 patients analyzed, 46 patients (41%) showed response to AZA (median cycles=6): CR=19, mCR=6, PR=12, and SDHI=9. Stable disease and treatment failure were observed in 20 (17%) and 47 patients (42%), respectively. Analysis of clinical features showed that platelet doubling after the first AZA cycle was significantly associated with a better response (58% vs. 31% responders, P=0.041). Forty-seven patients (42%) had chromosomal abnormalities. A positive co-occurrence between del(7q)/-7 and del(17p) was found (n=6, P5%) of bone marrow blasts (63% vs. 40%, P=0.016), higher frequency of complex karyotypes (40% vs. 15%, P=0.002), a positive co-occurrence with TP53 alterations (38% vs. 16%, P=0.009) and its methylation dynamics showed a strong trend towards predict the response to AZA: 57% of patients without DLC-1 methylation or who reduced it post-treatment responded favourably to the drug and 65% of patients who maintained or increased it did not respond (P=0.053). In addition, leukemia transformation was higher in MDS patients with DLC-1 methylation post-AZA than in the remaining MDS patients (58% vs. 21%, P=0.002). Conclusion: The combination of chromosomal alterations and genetic mutations together with the monitoring of platelet count and DLC-1 methylation could contribute to give light in myeloid neoplasms to the heterogeneity observed both in the response to AZA and in patient survival. Samples and data from patients included in this study were provided by the INCLIVA Biobank (PT13/0010/0004). Disclosures Hernandez Boluda: Incyte: Other: Travel expenses paid.

Introduction: Allogeneic hematopoietic cell transplantation (allo-HCT) constitutes the only curative treatment for myelofibrosis (MF), but its associated toxicity remains high. Prognostic risk models are widely used in clinical practice to select those MF patients who are more likely to benefit from transplantation. Recently, a new prognostic model, the Myelofibrosis Transplant Scoring System (MTSS), has been developed to predict the outcome of MF patients undergoing allo-HCT (Gagelmann N et al, Blood 2019). We aimed to evaluate the performance of such model in an independent series of patients. Methods: This is a retrospective study that included all adult patients who underwent first allo-HCT for MF between January 2005 and May 2019 in 8 Spanish hospitals. Patients transplanted after leukemic transformation were excluded. Survival probability from the time of HCT was estimated by the method of Kaplan-Meier and compared by the log-rank test. Each parameter of the MTSS was tested for its potential association with survival in univariate analysis. Cumulative incidence functions were used to estimate incidence of Graft-versus-Host-Disease (GVHD), Relapse Incidence (RI), and Non-Relapse Mortality (NRM) within a competing risk setting. Statistical analyses were performed with SPSS 19 (SPSS Inc./IBM, Armonk, NY) and R. Results: Demographics and transplant characteristics of the overall series of 107 MF patients are shown in Table 1. After a median follow-up from allo-HCT of 5.3 years, 49 patients (46%) had died. The survival probability at 1, 3, and 5-years was 64.5%, 52%, and 50%, respectively. Transplantation outcome improved over the years. Thus, the survival probability at 3-years was 35% (95% CI: 12-58), 50% (95% CI: 33-67), and 65% (95% CI: 50-80) during the time periods 2005-2009 (n=17), 2010-2014 (n=34), and 2015-2019 (n=56), respectively (P=0.038). The cumulative incidence of grade II-IV acute GVHD at day 100 was 45%. The cumulative incidence of relapse at 1, 3, and 5-years was 16%, 19.5%, and 19.5%, respectively. NRM probability at 1, 3, and 5-years was 24%, 29%, and 31%, respectively. In univariate analysis, the only parameter included in the MTSS that was significantly associated with survival was the Karnofsky performance status < 90% (HR: 1.9, 95% CI: 1.1-3.4; P=0.031). Neither age > 57 years (P=0.68), platelets 25 x 109/L (P=0.38), ASXL1 mutations (P=0.34), non-CALR/MPL driver mutation (P=0.57) nor HLA-mismatched unrelated donor (P=0.22) correlated with survival. Among other classical risk factors for transplant outcome, only a comorbidity index >= 3 was significantly associated with shorter survival (HR: 2.1, 95% CI: 1.1-4; P=0.017). A total of 64 cases had all required clinical and molecular data to calculate the MTSS. Figure 1 shows the survival curves of the different risk groups as defined by the MTSS. As can be seen, the prognostic model was not able to discriminate four risk groups. We then pooled together patients assigned to the low (n=26) and intermediate risk (n=23) groups, and those within the high (n=9) and very high risk (n=6) groups. On this basis, two-categories could be identified: standard risk (n=49 [77% of patients]) and high risk (n=15 [23%]). The 3-year overall survival was 65% (95% CI: 51-79) in the standard risk and 17% (95% CI: 0-46) in the high risk categories (P=0.060)(Figure 2). Conclusions: the MTSS did not discriminate four different risk categories in our series. Both, the limited number of cases and the differences in patients and transplant characteristics in our series as compared to those of the original MTSS cohort might account for this finding. Nevertheless, the MTSS was able to identify a subset of patients with a very poor prognosis after transplantation. Such information could be useful to assist on transplant decision-making. 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.

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.

Introduction Myeloproliferative Neoplasm (MPN) unclassifiable (MPN-U), is a heterogeneous disease that presents with an MPN-type clinical/ histological phenotype yet fails to meet diagnostic criteria for other MPN entities. Incidence is Methods This registry-based analysis was approved by the Chronic Malignancies Working Party of the EBMT. Patient selection was performed by identifying adult patients who underwent first allo-HCT for MPN-U between 2000-2015, using either Reduced Intensity Conditioning (RIC) or Myeloablative conditioning (MAC) as defined by standard EBMT criteria. Further data collection requests (MED-C) forms were sent to centres to improve data completeness. Statistical analyses were performed with SPSS 22 (SPSS Inc./IBM, Armonk, NY) and R. Overall Survival (OS) was calculated from the date of transplant until death or last observation alive. Cumulative incidence functions were used to estimate Non-Relapse Mortality (NRM) and Relapse Incidence (RI) within a competing risk setting. Results A total of 70 patients, 48 (69%) male and 22 (31%) female, with a confirmed diagnosis of MPN-U were analysed. Median age was 57 years (range (r), 22-70 years). Of these patients, 37 (53%) underwent allo-HCT in the period 2001-2010 and 33 (47%) between 2011-2015. MAC regimens were utilised in 31 (44%) patients while 39 (56%) received RIC. Patients were most frequently transplanted within the first two years from diagnosis, with a median time to allo-HCT of 13 months (r, 3-244 months). Diagnostic karyotype was normal in 36 (51%) and abnormal in 23 (33%) patients, with data missing for 11 (16%) patients. A total of 45 (64%) patients had received prior treatment, 23 (33%) patients were untreated and data was incomplete in 2 (3%) patients. Regarding donor type, 27 (39%) patients had a Matched Sibling Donor (MSD) and 43 (61%) an Unrelated Donor (URD). Most frequent conditioning regimens were TBI-based in the MAC cohort and Fludarabine-Busulphan in the RIC cohort. A trend towards higher rates of delayed/failed engraftment was noted in the RIC compared to MAC cohort (p=0.09). Where successful, median time to neutrophil engraftment in both cohorts was similar (18 days for MAC and 17 for RIC) and both platforms demonstrated similar platelet engraftment times (17.5 days). Incidence of grade II-IV aGVHD at 3 months was higher in the MAC (37%) compared to RIC cohort (16%; p=0.05) and the 12-month cumulative incidence of cGVHD for MAC was 52% (95%CI: 32.4, 71.6) and for RIC 32.1% (95%CI: 14.8, 49.4; p=0.117)). Median follow-up was 87 months (minimum and maximum of censored cases: 31 and 196 months). The median OS estimates at 1, 3 and 5-year were 77%, 55% and 42% (MAC) and 59%, 44% and 41% (RIC), respectively (p=0.33). No significant difference existed in OS rates between those who had pre-transplant therapy versus not. Relapse remained significant: cumulative incidences of relapse at 1,3 and 5-years were 10%, 23% and 27% (MAC) and 28%, 36% and 36% (RIC), respectively (p=0.28). NRM probabilities at 1, 3 and 5-years post allo-HCT were also considerable: 19%, 29%, and 34% (MAC) and 28%, 28% and 28% (RIC), respectively (p=0.84). Main causes of NRM were infection and GVHD. Univariate analysis associated use of an URD with a significantly worse OS and NRM compared with MSD. Moreover, the presence of abnormal karyotype at time of allo-HCT was associated with a trend towards a higher risk of relapse (p=0.06). Conclusions This study highlights the potentially curative role of allo-HCT in MPN-U and provides clinicians with robust engraftment, GVHD and outcome data. Both engraftment and OS rates appear acceptable yet NRM and CIR rates in both settings remain high and need to be addressed. The impact of abnormal karyotype at the time of allo-HCT and a trend towards higher risks of relapse requires further elucidation. Disclosures McLornan: Novartis: Honoraria; Jazz Pharmaceuticals: Honoraria, Speakers Bureau. Robin:Novartis Neovii: Research Funding. Chalandon:Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte Biosciences: Consultancy, Honoraria. Beelen:Medac GmbH Wedel Germany: Consultancy, Honoraria. Kröger:Sanofi-Aventis: Honoraria; Riemser: Research Funding; Novartis: Honoraria, Research Funding; Neovii: Honoraria, Research Funding; Medac: Honoraria; JAZZ: Honoraria; DKMS: Research Funding; Celgene: Honoraria, Research Funding. Milojkovic:Novartis: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau. Hernandez Boluda:Incyte: Other: Travel expenses paid.

Introduction: The only curative treatment for myelofibrosis (MF) remains allogenic haematopoietic cell transplantation (allo-HCT) although the risks of non-relapse mortality (NRM), relapse and graft rejection need to be taken into consideration. Therapeutic approaches following relapse after allo-HCT include symptom-directed management, chemotherapy, JAK2 inhibitors, adoptive immunotherapeutic approaches with donor lymphocyte infusion (DLI) and, in a minority, a second allo-HCT. Frequently, due to the advanced age of the recipient, early relapses, and numerous complications, 2nd allo-HCT can only be considered in a limited number of patients. Few studies evaluating the role of 2nd allo-HCT in MF following 1st relapse or primary/secondary graft rejection have been published to date. Methods and results: Patient selection was performed by identifying adult patients who underwent 2nd allo-HCT for MF between 2010-2017: 216 patients were analyzed; 64% were male, 78% had primary MF (PMF) and 22% secondary MF (sMF). Median age at the time of 2nd allo-HCT was 57 years, and median time from 1st allo-HCT was 8 months. Of this cohort, 56% of patients received a 2nd allo-HCT for relapse, 31% for graft failure and the reason was missing in 13%. A greater proportion was transplanted within 1 year from 1st allo-HCT (61 %) whilst 39% had 2nd allo-HCT > 1 year. A reduced Karnofsky performance status (KPS12 months, p=0.02). The 2-year relapse-free-survival (RFS) for the entire cohort was 44%. Only time elapsed from the 1st allo-HCT to 2nd was significantly associated with 2-year RFS (41% for ≤12 months, 49% for >12 months, p=0.05). Of note, the 2-year OS and RFS were comparable following use of the same or a different donor. The 2-year cumulative incidence of relapse and NRM were 22 and 34%, respectively. The time interval from 1st to 2nd allo-HCT appeared to be highly significant for NRM with patients transplanted ≤12 months having a higher 2-year NRM compared to those transplanted >12 months (40 vs 24%, respectively, p=0.008). A trend for higher NRM was the reason for 2nd allo-HCT: patients transplanted for graft rejection had a 2-year NRM of 45% compared to 31% for those with relapse (p=0.06). Conclusions: This analysis supports the utilization of a 2nd allo-HCT for patients with MF who have presented with graft failure or relapse following a 1st allo-HCT. In univariate analysis, overall outcome appears worse in patients being transplanted after graft failure as well as for those transplanted within 1 year after 1st allo-HCT, due to increased NRM. Of note, the use of either the original or a different donor are associated with similar outcomes. Further work is required to elucidate other risk factors, GVHD rates and to define the optimal conditioning regimen in this setting. Table. Disclosures Robin: Novartis Neovii: Research Funding. Kröger:Sanofi-Aventis: Honoraria; Riemser: Research Funding; Novartis: Honoraria, Research Funding; Neovii: Honoraria, Research Funding; Medac: Honoraria; JAZZ: Honoraria; DKMS: Research Funding; Celgene: Honoraria, Research Funding. Angelucci:Celgene: Honoraria, Other: Participation in DMC; BlueBirdBio: Other: Local advisory board; Jazz Pharmaceuticals: Other: Local advisory board; Roche: Other: Local advisory board; Vertex Pharmaceuticals Incorp., and CRISPR Therapeutics: Other: Participation in DMC; Novatis: Honoraria, Other: Chair Steering Committee TELESTO protocol. Dreger:AbbVie, AstraZeneca, Gilead, Janssen, Novartis, Riemser, Roche: Consultancy; AbbVie, Gilead, Novartis, Riemser, Roche: Speakers Bureau; MSD: Membership on an entity's Board of Directors or advisory committees, Other: Sponsoring of Symposia; Neovii, Riemser: Research Funding. Platzbecker:Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria. Rambaldi:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Italfarmaco: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: travel support, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Omeros: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding. Ladetto:ADC Therapeutics: Honoraria; Pfizer: Honoraria, Speakers Bureau; Celgene: Honoraria; J&J: Honoraria; Roche: Honoraria; AbbVie: Honoraria; Acerta: Honoraria, Speakers Bureau. Hernandez Boluda:Incyte: Other: Travel expenses paid. McLornan:Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Novartis: Honoraria. Chalandon:Incyte Biosciences: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria.

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.

Myeloablative single-unit umbilical cord blood transplantation (sUCBT) using busulfan, thiotepa, fludarabine, and antithymocyte globulin (Grupo Español de Trasplante Hematopoyético [GETH]-2005 protocol) resulted in high rates of engraftment and high antitumor activity. We designed a new graft-versus-host disease prophylaxis, substituting long-term steroids with mycophenolate mofetil together with a slight reduction of antithymocyte globulin (GETH/Gruppo Italiano Trapianto Midollo Osseo [GITMO]-2008 protocol). The results in 145 consecutive patients were compared with those obtained in 88 patients from the previous GETH-2005 trial. The cumulative incidence (CI) of myeloid engraftment at 60 days for patients in the GETH-2005 and GETH/GITMO-2008 trials was 94% and 88%, respectively, at a median time to neutrophil recovery of 19 and 23 days, respectively (P

Introduction: Myeloid/lymphoid neoplasms (MLNs) with rearrangement of FGFR1 on chromosome band 8p11 are rare but aggressive neoplasms characterized by heterogeneous presentation with myeloid and/or lymphoid proliferation, extramedullary involvement, and rapid progression to blast phase (Strati P, et al., Leuk Lymphoma. 2018;59:1672-1676). FGFR1 gets constitutively activated through fusion genes involving various partner genes, most frequently ZMYM2-FGFR1 or BCR-FGFR1 as consequence of a t(8;13)(p11;q12) or a t(8;22)(p11;q11), respectively. Chemotherapy is usually ineffective, effective targeted treatment has not been described, and allogeneic hematopoietic stem cell transplant (alloHSCT) is the only potentially curative option. Pemigatinib, a selective, potent, oral inhibitor of FGFR1, 2, and 3, has shown efficacy in patients with FGF/FGFR-activated tumors, including cholangiocarcinoma and urothelial carcinoma. We report interim results from the ongoing fight-203 study (NCT03011372) of pemigatinib in patients with FGFR1-rearranged MLNs. Methods: Fight-203 is a phase 2, open-label study enrolling patients ≥ 18 years of age with FGFR1-rearranged MLN. Patients enrolled in the study must have progressed on ≥ 1 prior treatment and be ineligible for alloHSCT. Patients receive a daily oral dose of pemigatinib 13.5 mg on a 21-day cycle (2 weeks on, 1 week off) until disease progression or unacceptable toxicity. The primary endpoint is overall clinical benefit rate, which includes complete clinical (CR) or partial clinical response (PR), and either complete or partial cytogenetic response (CCyR, PCyR). Secondary endpoints include duration of response/benefit, progression-free survival, overall survival, and safety/tolerability. Efficacy is assessed by evaluation of bone marrow histomorphology changes, standard cytogenetic and FISH evaluation of the FGFR1 rearrangement, and PET/CT scan. Results: At data cutoff (July 23, 2018), 14 patients were enrolled. Ten patients who had ≥ 1 response assessment were included in the analysis (Table). Patients received an average of 6.9 cycles of pemigatinib (range, 2-12 cycles). Median number of prior lines of therapy was 3 (range, 0-5), including 2 patients who received alloHSCT. Eight patients (80%) had a major CyR, including 6 patients with CCyR and 2 with PCyR. Eight patients (80%) had a CR or PR in bone marrow, peripheral blood, and extramedullary disease. One patient died of progression to myeloid blast crisis, 2 patients were bridged to alloHSCT, and 7 patients are ongoing. The most common treatment-emergent adverse events (AEs) were hyperphosphatemia (n=7 [70%]), diarrhea (n=5 [50%]) and anemia (n=5 [50%]); hyperphosphatemia was managed with diet and phosphate binders. Nine events in 4 patients (40%) were grade 3/4; 2 of these events (diarrhea and leukopenia) in 2 patients were related to pemigatinib. There were no drug-related AEs leading to dose interruption, dose reduction, or discontinuation. Conclusions: Pemigatinib showed promising efficacy, with an 80% major CyR rate accompanied by complete or partial remission, and was generally well tolerated by patients with FGFR1-rearranged MLN. The protocol was amended to allow continuous dosing, and the study is currently enrolling. Disclosures Verstovsek: Celgene: Membership on an entity's Board of Directors or advisory committees; Italfarmaco: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Gotlib:Blueprint Medicines: Consultancy, Honoraria, Research Funding; Deciphera: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Research Funding; Promedior: Research Funding; Kartos: Consultancy; Incyte: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Mead:Celgene: Research Funding; Bristol-Myers Squibb: Consultancy; Evotek: Research Funding; ARIAD: Consultancy; Cell Therapeutics: Consultancy; Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Elstar: Research Funding. Hochhaus:Bristol-Myers Squibb: Research Funding; Novartis: Research Funding; Incyte: Research Funding; Takeda: Research Funding; Pfizer: Research Funding. Kiladjian:AOP Orphan: 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; Celgene: Membership on an entity's Board of Directors or advisory committees. Hernandez Boluda:Incyte: Consultancy; Novartis: Consultancy. Asatiani:Incyte: Employment, Equity Ownership. Lihou:Incyte: Employment, Equity Ownership. Zhen:Incyte: Employment, Equity Ownership. Reiter:Incyte: Consultancy, Honoraria.

Introduction: Transformation to secondary myelofibrosis (MF) occurs as part of the natural history of polycythemia vera (PV) and essential thrombocythemia (ET), the two more indolent Ph-negative myeloproliferative neoplasms (MPN). Once transformed, survival is remarkably shorted. Chronic inflammation plays a critical role in the progression of MPN, driving clonal expansion toward end stage disease. Importantly, MPN are characterized by the production of inflammatory cytokines, by both malignant and non-malignant clone. Inflammation and cancer share a common pathway, i.e. NF-κB. Interestingly, miR-146a regulates TLR/NF-κB pathway through the inhibition of its targets, IRAK1 and TRAF6, decreasing the production of cytokines. Based on: i) miR-146a-/- mice develop an MF-like phenotype with aging; and ii) miR-146a polymorphism (miRSNPs) rs2431697, influences its expression levels (50% decrease in TT individuals); we hypothesized that lower miR-146a-5p levels associated to this miRSNPs may result in high risk to develop MF. Objective: To evaluate the association of rs2431697 with MF transformation and to study the molecular mechanisms beyond this association. Methods: We genotyped rs2431697 in 938 patients (312 MF, 299 PV, and 327 ET) recruited from 13 tertiary Spanish institutions belonging to GEMFIN and 600 controls. The levels of miR-146a and IRAK1 were evaluated by qRT-PCR in total blood RNA of homozygous patients (TT=30, CC=25) with PV or ET and in healthy subjects (TT=7, CC=7). In miR-146a-/- mice, 2 and 9 months old, we evaluated spleen size and cellularity: degree of fibrosis in bone marrow (H&E and silver staining); and STAT3 and pSTAT3 in granulocytic lysates by western blot. Results: Association analysis, taken controls as reference, showed that TT genotype (associated in the literature with low levels of mir-146a) is associated to MF with an OR of 1.36 (1.01-1.82, p=0.04). Among MF patients, the subgroup with the greatest differences was the one of secondary MF (OR = 1.47, CI: 0.98-2.20) (Table 1 a,b). Next, we compared the genetic frequencies of rs2431697 SNPs between the secondary MF patients and the population in risk. Confirming our hypothesis, we observed an enrichment of TT genotype in the post-PV/TE MF group (n=132) compared to the PV+TE group (n=626) (OR=1.51; p Conclusion: rs2431697-TT is an independent marker of early progression to secondary MF. The lower expression of miR-146a that this SNP confers is associated with an increase in JAK-STAT3 signaling. Our findings include, for the first time, miR-146a in the MPN signaling pathways. Thus, miR-146a, modulating the activation of NF-kB-IRAK1, could indirectly regulates JAK-STAT3 signalling. CINC424AES05T Disclosures Ferrer Marin: Novartis: Consultancy, Research Funding; Incyte: Consultancy. Hernandez Boluda:Incyte: Consultancy; Novartis: Consultancy. García Gutiérrez:Incyte: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau. Gómez-Casares:Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau. Besses:Novartis: Honoraria, Research Funding; Shire: Honoraria.

Introduction: Triple negative primary myelofibrosis (TN-PMF) and myelodysplastic syndromes with fibrosis (F-MDS) are rare entities, often difficult to distinguish each other. Currently, no specific molecular markers allowing a precise differential diagnosis are available. In this sense, next generation techniques (NGS) might be useful to distinguish between both entities and to refine prognosis. Methods: Thirty-nine patients with TN-PMF (n=16) or F-MDS (n=23) were analyzed, Targeted NGS was performed in 28 cases (10 TN-PMF and 18 F-MDS) using the Sophia Genetics Myeloid Tumor Solution Panel including the following genes: ABL1, ASXL1, BRAF, CALR, CBL,CEBPA, CSF3R,CSNK1A1,DNMT3A, ETV6, EZH2, FLT3,HRAS, IDH1, IDH2, JAK2, KIT, KMT2A, KRAS, MPL, NPM1, NRAS, PTPN11, RUNX1, SETBP1, SF3B1, SRSF2, TET2, TP53, U2AF1, U2AF2, WT1 and ZRSR2. High molecular risk (HMR) was defined by the presence of any mutation in ASXL1, SRSF2, EZH2 or IDH1/2 genes. Clinical and biological data at diagnosis were compared among both groups of patients, including bone marrow cytogenetics, bone marrow histology, and the results from NGS analysis. The probabilities of survival and progression to acute leukemia were estimated by the Kaplan Meier method using the log rank test for comparisons. Results: Median age at diagnosis for the whole series was 63 years (range 42-87). Cytogenetic abnormalities were detected in 16 (57%) out of 28 assessable patients, being classified as low risk (n=17), intermediate risk (n=5), and high risk (n=6) There were no significant differences among TN-PMF and F-MDS regarding age, sex, hematological values, spleen size or cytogenetic risk or the number of blasts in peripheral blood or bone marrow. Mutations were detected by NGS in 26 out of 28 (93%) patients. Median number of mutations was 3 (Range: 1-7). Most frequent mutated genes were: ASXL1 n=10 (36%), TET2 n=7 (25%), SRSF2 n=6 (21%), DNMT3A n=6 (21%), U2AF1 n=5 (18%), ETV6 n=4 (14%), SETBP1 n=3 (11%), RUNX1 n=3 (11%), EZH2 n=2 (7%), TP53 n=2 (7%), ZRSR2 n=2 (7%) and KMT2A n=2 (7%). Mutations in either TET2, U2AF1, SETBP1, TP53 or RUNX1 genes were observed in only 1 patient with TN-PMF in contrast with 12 out of 18 (67%) F-MDS cases (p=0.006). HMR mutations were detected in 12 cases (43%) with 7 of them (21%) carrying two or more HMR mutations. There were no significant differences among TN-PMF and F-MDS regarding the total number of mutations per case or in the presence of HMR mutations. Median survival was 1.6 and 3.7 years for patients with TN-PMF and F-MDS, respectively (p=0.4). Leukocyte count > 25x109/L and presence of blasts ≥ 1% in peripheral blood were associated with a significantly lower survival. High risk cytogenetics and ≥ 2 HMR mutations were associated with a tendency towards lower survival. Median survival was 1.6 years in patients with ≥ 3 mutations in comparison with 8.3 years in those with < 3 mutations, respectively (p=0.03). Progression to acute myeloid leukemia was observed in 11 patients, resulting in a probability of 32% at 3 years. There were no significant differences in the probability of progression to acute leukemia among TN-PMF and F-MFDS. Time to acute leukemia was significantly shorter in patients with ≥ 3 mutations (3-year probability 45% versus 16%, p=0.039). Conclusions: TN-PMF and F-MDS showed a high rate of mutations in myeloid genes with TET2, U2AF1, SETBP1, TP53 or RUNX1 being more frequently mutated in F-MDS. Despite survival being short in both entities, NGS allowed the identification of a subgroup of patients with especially poor prognosis characterized by the presence of ≥ 3 mutations. Disclosures Hernandez Boluda: Novartis: Consultancy; Incyte: Consultancy. Cervantes:Hospital Clinic Barcelona: Employment; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees.

Introduction: Over half of patients with chronic myeloid leukemia (CML) in sustained deep molecular remission do not lose the major molecular response (MMR) after stopping treatment with tyrosine kinase inhibitors (TKI). This strategy is safe in controlled clinical trials, but there is scarce information on its applicability in the real-life setting. We aimed to assess if treatment cessation was feasible in clinical practice in a large nationwide series of CML patients from Spain. Methods: This retrospective study comprised a series of 236 patients in chronic-phase CML who discontinued TKI treatment outside of clinical trials between April 2009 and February 2018 in 33 Spanish institutions. Inclusion criteria were: a) TKI treatment duration >3 years; b) sustained MR4.5 in >4 consecutive determinations (one single point in MR4 was acceptable) during >2 years; c) molecular monitoring in a reference laboratory expressing the results on the International Scale (IS). Patients who had undergone allogeneic hematopoietic stem-cell transplantation were excluded. Molecular relapse was defined as consecutively detectable BCR-ABL1 transcripts showing a ≥1 log increase or loss of MMR in any single sample. Treatment-free remission (TFR) was estimated by the method of Kaplan-Meier and defined as the time from TKI discontinuation to the date of restarting therapy for any reason or, if treatment was not restarted, the date of last contact. Incidence of molecular relapse was calculated using the cumulative incidence function with resumption of TKI treatment in the absence of molecular relapse and death in MMR as competing events. Analysis of factors predicting molecular relapse was done by the method of Fine and Gray. Results: Table 1 shows the main characteristics of the series. Median follow-up from treatment discontinuation was 21.5 months, and 5 patients died in MMR due to CML unrelated causes. TKI therapy was reinitiated due to molecular relapse (MMR loss: n=52, increase >1 log in BCR-ABL transcript level at two consecutive assessments without losing MMR: n=12), patient preference (n=2), and severe withdrawal syndrome (n=1). One additional patient lost MMR after 20 months from treatment cessation but decided not to be retreated, with spontaneous recovery of MMR. The probability of TFR at 4 years was 64% (95% Confidence Interval [CI]: 55%-72%)(Figure 1). The cumulative incidence of molecular recurrence was 33% (95% CI: 26%-38%) at 3 years (Figure 2). Forty-nine relapses (75% of total) occurred in the first 6 months. The latest MMR loss was detected 30 months after treatment stop. One patient restarted treatment 44 months after TKI discontinuation due to ≥1 log increase in BCR-ABL1 transcripts in two consecutive samples without losing MMR. In univariate analysis, duration of TKI treatment of less than 5 years (P=0.005) and time in RM4.5 shorter than 4 years before TKI discontinuation (P=0.003) were both significantly associated with a higher incidence of molecular recurrence. No patient progressed to the advanced phases of CML. At the time of restarting treatment, the median BCR-ABL1 IS was 0.3%, with this value being >5% in only 7 instances. Most patients (81%) received the same TKI that they were taking before the trial of treatment cessation. Median follow-up after treatment resumption was 20 months. Among the 64 patients who restarted treatment due to molecular relapse, 46 of 52 cases regained MMR after a median time of 3 months, and 47 of 64 regained MR4.5 after a median time of 5 months. Response status at last control was: MR4.5 (n=196), MR4 (n=15), MMR (n=14), complete cytogenetic response (n=10), and other (n=1). Fifty-one patients (22%) developed musculoskeletal or joint pain after treatment cessation. In patients stopping imatinib, a significant increase in Hb levels, leukocyte counts, total lymphocyte counts, platelet counts, and cholesterol levels was observed. At 6 months, an increase in Hb level >2 g/dL was observed in 47% of patients with anemia. By contrast, nilotinib discontinuation was not followed by any relevant change in laboratory values. Conclusions: Our results confirm that treatment discontinuation is feasible and safe in clinical practice in Spain. Duration of TKI treatment of less than 5 years and a time in RM4.5 shorter than 4 years before TKI discontinuation were significantly associated with a higher incidence of molecular recurrence. Disclosures Hernandez Boluda: Incyte: Consultancy; Novartis: Consultancy. García Gutiérrez:Incyte: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Ferrer Marin:Incyte: Consultancy; Novartis: Consultancy, Research Funding. Cervantes:Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hospital Clinic Barcelona: Employment.

Background and objective. An important proportion of patients with polycythemia vera (PV) and essential thrombocythemia (ET) are diagnosed in the seventh and eighth decades of life. Because of the chronic course of PV and ET and the advanced age of patients, many will actually die from age-related ailments instead of the myeloproliferative neoplasm, so the disease's impact on life-expectancy remains largely unknown. This registry‐based study was aimed at investigating the excess mortality attributable to PV and ET in a large series of patients diagnosed and managed according to modern criteria. Methods. We queried the databases of the Spanish Group for Chronic Myeloproliferative Neoplasms (GEMFIN) to retrieve patients diagnosed with PV or ET after 1980. Criteria for diagnosis and treatment modalities were the internationally recommended ones in each period. Excess mortality was defined as the complementary of the ratio between the actuarial survival observed in the cohort of patients and the expected survival derived from the general Spanish population matched to the patients by age, sex, and calendar year at diagnosis, and was estimated by the Dickman's method (Stat Med 2004;23:51). Spanish life-tables stratified by age, sex, and calendar year were obtained from the Human Mortality Database (www.mortality.org). Results. A total of 3,268 patients were included in the study (PV: 1,731; ET: 1,537). Median age (interquartile range) and sex distribution in the PV and ET groups were 67 (55-75) years, 48% females, and 62 (48-74) years, 61% females, respectively. At the study closing date, 270 (16%) patients with PV and 202 (13%) with ET had died. Estimated median survival was 20.2 years for PV patients and 23.8 years for ET patients. Transformation into acute myeloid leukemia/myelodysplastic syndrome was diagnosed in 76 (4.4%) patients with PV and 63 (4.1%) with ET. Three hundred and seventy-one patients (170 ET, 201 PV) had one or more episodes of thrombosis over the course of the disease. No significant excess mortality attributable to ET was detected at 20 years from diagnosis (figure 1a). In PV, mortality did not significantly deviate from matched general population until 18 years from diagnosis (figure 1b). In both diseases, excess mortality significantly increased after the first recorded thrombotic event (figure 1c). Conclusion. From the population viewpoint, ET and PV do not carry an increased excess mortality until late in the second follow-up decade or later. Nevertheless, appearance of a thrombotic event significantly increases the subsequent excess mortality. Figure 1 Figure 1. Disclosures Hernandez Boluda: Incyte: Consultancy; Novartis: Consultancy. Ferrer Marin:Novartis: Consultancy, Research Funding; Incyte: Consultancy. Gómez-Casares:Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau. Cervantes:Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hospital Clinic Barcelona: Employment.

Attempts to optimize outcomes in cord blood transplantation (CBT) by using new conditioning regimens and standardization of cord blood unit selection are warranted. In all, 88 patients (18 children and 70 adults) with hematological malignancy from nine Spanish institutions underwent a single-unit CBT after an i.v. BU-based myeloablative conditioning regimen. All evaluable patients except one engrafted. The overall cumulative incidence (CI) of myeloid engraftment was 94% at a median time of 19 days. In multivariate analysis, nonadvanced disease stage was the only factor with a favorable impact on myeloid engraftment. The CI of acute GVHD grades II-IV and chronic extensive GVHD were 24% each. The CI of nonrelapse mortality at 100 days, 180 days and 5 years was 14, 23 and 44%, respectively. The 5-year CI of relapse was 18%, whereas disease-free survival (DFS) was 46%, 39% and 11% for patients transplanted in early, intermediate and advanced stages of the disease, respectively. Our study shows high rates of engraftment with fast neutrophil recovery in patients undergoing single-unit CBT using a BU-based conditioning regimen. Long-term DFS can be achieved in a substantial number of patients with high-risk hematological malignancies, particularly when transplanted in an early stage of the disease.