Unclassifiable Myeloproliferative Neoplasms Research Articles

Health-Related Quality of Life in Patients with Philadelphia-Negative Myeloproliferative Neoplasms: A Nationwide Population-Based Survey in Denmark.

Simple SummaryThe aim of this research was to investigate the health-related quality of life (HRQoL) in patients with Philadelphia-negative myeloproliferative neoplasms (chronic blood cancers) in Denmark. A nationwide questionnaire survey covering functioning, symptom burden, symptom profile, QoL, and lifestyle was performed. Patients registered in the National Patient Register with a diagnosis of Philadelphia-negative myeloproliferative neoplasm were invited. A total of 2228 patients participated in the survey and these could be divided into groups of participants with different subtypes of Phildelphia-negative myeloproliferative neoplasms. The HRQoL across groups of participants with different subtypes of the disease was compared, and the HRQoL of all participants and the general population was compared in order to investigate for a potential difference. The participants reported their HRQoL to be inferior to the general population, but the difference was minor. The differences in HRQoL across groups of participants with different subtypes of the disease were subtle. Fatigue and sexual problems were prevalent and burdensome. Participants reported a slightly healthier lifestyle than the general population. Understanding HRQoL of these patients is a necessity to be able to provide the best treatment and rehabilitation activities. Previous studies have clarified that many patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) have burdensome symptom profiles and accordingly impaired functioning and quality of life (QoL). In Denmark, all MPN patients are affiliated with public hospitals and because of a healthcare system financed by taxpayers these patients do not have any financial costs related to the hematological disease. Diagnoses are recorded for all patients in hospitals, and diagnosis codes are communicated to the National Patient Register (NPR). Owing to this, it was possible to contribute to the elucidation of Philadelphia-negative MPN patients’ health-related quality of life (HRQoL), by conducting a nationwide, population-based, cross-sectional HRQoL survey of these patients with cost-free access to the best available, suitable medical treatment. The survey contained validated questionnaires covering functioning, symptom burden, symptom profile, QoL, and additional questions on lifestyle. Information on comorbid diagnoses was obtained from the NPR. The participants’ HRQoL was compared to the general population. Moreover, differences in HRQoL across essential thrombocythemia, polycythemia vera, myelofibrosis, and unclassifiable MPN participants were investigated, adjusted for age, sex, comorbidity, and lifestyle. To the best of our knowledge this is the first survey of HRQoL in patients with unclassifiable MPN. A total of 2228 Philadelphia-negative MPN patients participated. The participants reported their HRQoL to be inferior to the general population, but the difference was minor. The differences in HRQoL across groups of participants with different MPN subtypes were subtle. Fatigue and sexual problems were prevalent and burdensome. Overall, participants reported a slightly healthier lifestyle compared to the general population.

Hydroxyurea Reduces Neutrophil Extracellular Trap Formation in Myeloproliferative Neoplasms

Introduction: Ph-negative myeloproliferative neoplasms (MPNs) are a group of clonal stem-cell disorders with an elevated risk for thrombosis. Leukocytosis is a well-known risk factor for thrombosis. Neutrophils from MPN patients display features of activation. On stimulation, neutrophils produce neutrophil extracellular traps (NETs), which have been implicated in the pathogenesis of thrombosis. Myeloperoxidase-conjugated DNA levels (a specific NET marker) have been found increased in plasma of thrombotic MPN patients (Guy, A, ISTH 2019 OC 77.3). Ex vivo, activated neutrophils from JAK2V617F patients are primed to form NETs, diminishing under ruxolitinib treatment. Mice with conditional knock-in of JAK2V617F have increased NETs formation and thrombotic events. Inhibition of JAK/STAT signaling by ruxolitinib abrogated NETs formation and reduced thrombosis in this murine model (Wolach, O,Sci. Transl. Med. 2018). Thus, a link between JAK2V617F expression, NETs formation and thrombosis has been suggested (Wolach, O, 2018). It remains unclear whether, in MPN patients, JAK/STAT independent pathways are implicated in the NETs formation. With this aim, we explored the effects of different cytoreductors in NETs formation. Patients and Methods: In a multicentric study conducted at Hospital General Universitario Morales Meseguer (Murcia, Spain) and Hospital del Mar (Barcelona, Spain), EDTA plasma samples were collected from MPN patients (n=104). Patients include polycythemia vera (PV, n=35, all of them JAK2V617F), essential thrombocythemia [ET, n=47; 38 JAK2V617F, 4 CALRmut, 5 triple negative (TN)], myelofibrosis (MF, n=9; 4 JAK2V617F, 2 CALRmut, 3 TN), and unclassifiable MPN by WHO-2016 (MPN-u, n=13; 12 JAK2V617F, 1 CALRmut). Samples were collected at different time points following up the disease: at diagnosis or before any cytoreductive treatment, time 0, (n=100), less than 6 months of treatment (time 6; n=60), from 6 to 12 months of treatment (time 12; n=60), and from 12 to 24 months of treatment (time 24; n=49). Among the 104 patients, we had clinical information about treatment on 99 cases, included hydroxyurea (HU, n=69), ruxolitinib (n=15), IFN-α (n=2), and non-treated (n=13, all basal samples). We measured citH3-DNA complexes, as specific marker of NETs, by ELISA using rabbit anti-citH3 (Abcam) and peroxidase-conjugated anti-DNA antibody (Cell Death Detection ELISA). The absorbance at 405 nm (A405) was measured in a plate reader (Biotek®). Thus, we followed up the NETosis marker evolution with treatment over time. One-tailed and paired Wilcoxon test was applied and p<0.05 was taken as statistical significance. Results: Overall, regardless of the treatment, we observed a reduction of citH3-DNA levels over time (Fig. 1A), being these significant between time 0 and times 6 and 12 (p=0.02 for both time-points), Importantly, patients treated with HU showed a substantial reduction of NETs in all time-points (Fig. 1B, left), which was statistically significant between times 0 and 6 (p=0.03) and between times 0 and 24 (p=0.02). Although in patients treated with ruxolitinib, the citH3-DNA levels seem to be reduced at time 12, the difference was not significant (Fig. 1B, right), probably because of the small sample size. Regarding the MPN phenotype, decrease of citH3-DNA levels over time was only observed in PV patients (Fig. 1C, left), specially at time 12 (p=0.03). In contrast, under cytoreductive treatment, ET patients did not show significant differences in NETs levels over time (Fig. 1C, middle). In MF, there were not enough samples to obtain a clear conclusion (Fig. 1C, right). Regarding the driver gene mutations, we detected a significant decrease in the citH3-DNA levels in JAK2V617F patients (Fig. 1D, left), specifically between basal time and times 6 and 12 (p<0.02 for both time-points). Unfortunately, there are not enough samples to obtain a clear conclusion in CALRmut (Fig. 1D, right) and TN patients. Conclusions: Our results showed that hydroxyurea reduces NETosis levels in plasma from MPN patients, suggesting that JAK-STAT independent pathways could be implicated in the NET formation. Hydroxyurea could decrease thrombosis in MPN patients, not just reducing the number of functionally abnormal cells in peripheral blood, but also by abrogating NET formation. Acknowledgements: This study was supported in part by ISCIII (PI18/00316 & PI16/0153) & Fundación Séneca (20644/JLI/18). Disclosures Bellosillo: Qiagen: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau.

NFE2 Mutations Impact AML Transformation and Overall Survival in Patients with Myeloproliferative Neoplasms (MPN)

Introduction: MPN are a heterogeneous group of chronic hematological malignancies often resulting from a combination of a driver gene mutation (JAK2, MPL or CALR) and a variety of somatic mutations harboring diverse prognosis values. A subset of MPN patients carry somatic mutations in the hematopoietic transcription factor NFE2 (nuclear factor erythroid 2) resulting in a functionally enhanced truncated form of NFE2 (Jutzi JS et al., JEM, 2013). Moreover, epigenetically induced overexpression of NFE2 has recently been reported in the majority of MPN patients (Peeken JC et al., Blood, 2018). In transgenic murine models, NFE2 overexpression results in an MPN phenotype (thrombocytosis, leukocytosis, EPO-independent colony formation, characteristic bone marrow histology and expansion of stem and progenitor compartments) and has recently been shown to predispose to the acquisition of additional genetic abnormalities and subsequent leukemic transformation (Kaufmann KB et al., JEM, 2012) (Jutzi JS et al., Blood, 2019). However, clinical impact of NFE2 mutations in MPN patients remains unknown. The aim of this study was to evaluate the phenotypic characteristics and prognostic impact of NFE2 somatic mutations in a large mono-centric cohort of MPN patients. Methods: A total of 1243 consecutive patients were diagnosed with MPN according to WHO criteria and followed in our hospital between January 2011 and May 2020. This study included 707 of them in whom a next-generation sequencing (NGS) molecular analysis targeting 36 myeloid genes was performed at diagnosis and/or during follow-up. Clinical and biological characteristics at time of diagnosis and follow-up were collected from medical charts and electronic medical records. Statistical analyses were performed using the STATA software (STATA 15.0 Corporation, College Station, TX). Results: In our cohort, 411 patients presented with polycythemia vera (PV), 577 with essential thrombocythemia (ET), 184 with primary or pre-fibrotic myelofibrosis (PMF), 59 with unclassified MPN and 12 with MDS/MPN. Median age at diagnosis was 51 years [40-63]. 73.1% patients had a JAK2V617F mutation, 14.1% a CALR mutation and 3.3% a MPL mutation. Overall, 64 (9.05%) patients harbored a NFE2 mutation with a variant allelic frequency (VAF) ≥ 0.5% and 36 had a VAF ≥ 5%, the latest were considered as NFE2 mutated for the rest of the study as VAF <5% may refer to a minor clone without clinical relevance. NFE2 mutations were present in 7.3%, 5.3% and 3.6% of PV, PMF and ET patients respectively. No significant association between the presence of NFE2 mutation and clinical/molecular MPN characteristics (driver mutation, constitutional symptoms, splenomegaly, blood counts, cytogenetic and other molecular features) was observed using a logistic regression association model. Median follow-up was 103.8 months, IQR [47.2; 175.6]. In terms of response to therapy, 52.8% of patients achieved complete response, complete hematological response or clinical improvement in NFE2 mutated vs 61.7% in non-mutated patients (p= 0.026). Interestingly, presence of a NFE2 mutation (HR 9.92, 95%CI[3.21; 30.64], p< 0.001), age at diagnosis (HR 1.09, 95%CI[1.05; 1.12], p< 0.001), PMF subtype (HR 6.92, 95%CI[2.81; 17.06], p < 0.001) and high-risk mutations (ASXL1, EZH2, SRSF2, IDH1/2 and U2AF1) (HR 2.45, 95%CI[1.14; 5.28], p=0.021) were independently associated with AML/MDS transformation free survival (TFS) in a COX regression multivariate analysis (Figure A). Presence of a NFE2 mutation was also independently associated with overall survival (OS) (HR 9.37, 95%CI [4.18; 21.03], p<0.001) (Figure B). Median TFS were 216.1 months and not reached, while median OS were 144.2 months and not reached for NFE2 mutated and non-mutated patients, respectively. No difference was observed in terms of thrombo-hemorrhagic events (HR 0.73; 95%CI [0.10; 5.21], p=0.752) and secondary myelofibrosis free survivals (HR 0.67; 95%CI [0.09; 4.87], p=0.693). Conclusion: In this retrospective study we show that presence of NFE2 mutations with a VAF ≥5% is independently associated with an increased risk of leukemic transformation and shorter overall survival. These findings are in line with recently reported animal models and suggest that NFE2 mutations screening should be routinely performed in MPN patients. Disclosures Rea: 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; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Kiladjian: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; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Benajiba:Gilead Foundation: Research Funding.

Pathological characteristics of megakaryocytes in myeloproliferative neoplasms and their correlation with driver gene mutations

目的探讨骨髓增殖性肿瘤（MPN）巨核细胞病理特征及其与起始基因突变的相关性。方法收集2012年2月至2017年10月于中国医学科学院血液病医院就诊的160例初诊MPN患者，根据世界卫生组织（WHO）2016年MPN诊断标准对患者骨髓活检组织切片进行重新评估。结果160例患者中男72例（45.0％），女88例（55.0％），中位年龄59（13～87）岁。重新评估后真性红细胞增多症（PV）39例，原发性血小板增多症（ET）33例，纤维化前/早期原发性骨髓纤维化（pre-PMF）37例，明显期原发性骨髓纤维化（overt PMF）37例，真性红细胞增多症后骨髓纤维化（post-PV MF）2例，原发性血小板增多症后骨髓纤维化（post-ET MF）1例，MPN-未分类（MPN-U）11例。按PV、ET、pre-PMF及overt PMF疾病亚型顺序，密集成簇分布、少分叶核及裸核巨核细胞逐渐增加，红系增生程度正常及增高的比例逐渐降低，1级及以上网状纤维、胶原及骨硬化的比例逐渐升高。相关性分析示密集成簇分布、少分叶核及裸核巨核细胞占比与红系增生程度呈负相关，与粒系增生程度及纤维化程度呈正相关。对pre-PMF及overt PMF患者病理特征的相关性分析示密集成簇分布及裸核巨核细胞占比与纤维化程度呈正相关。JAK2V617F突变MPN患者红系增生程度明显增高（P＝0.022），CALR突变MPN患者疏松成簇、密集成簇、骨小梁旁分布及裸核巨核细胞明显增多（P＝0.055，P＝0.002，P＝0.018，P＝0.008），1级及以上网状纤维、胶原及骨硬化比例增高（P＝0.003，P<0.001，P＝0.001）。伴JAK2V617F突变pre-PMF及overt PMF患者骨髓增生程度较高（P＝0.037），伴CALR突变患者巨大体积及密集成簇分布巨核细胞明显增多（P＝0.059，P＝0.055），1级及以上胶原及骨硬化的比例明显增高（P＝0.011，P＝0.046）。结论不同亚型MPN患者骨髓巨核细胞病理改变特征各异，其病理异常特征与纤维化水平相关。CALR突变可能与巨核细胞病理异常特征及骨髓纤维化水平相关。

Risk of Inflammatory Bowel Disease in Patients with Chronic Myeloproliferative Neoplasms: A Danish Nationwide Cohort Study.

Simple SummaryWe wanted to investigate the risk of inflammatory bowel disease (IBD) in patients with Philadelphia-negative chronic myeloproliferative neoplasms (MPNs), since up to 50% of these patients experience gastrointestinal symptoms and several studies have suggested an association between hematological cancers and IBD. We included ∼8000 patients and ∼80,000 sex- and age-matched, non-MPN comparisons from the general population, and found that MPN patients were two to three times more likely to develop IBD, but the absolute risk of IBD was modest. In addition, MPN patients were also 40% more likely to have a prior diagnosis of IBD. Our results pose intriguing questions about the causal pathways linking MPN and IBD, which may include genetic, treatment-related and immune-mediated factors. Moreover, it shows that abdominal symptoms in MPN patients may not only be caused by an enlarged spleen or treatment side-effects. Conversely, persistent leucocytosis and/or increased platelets in IBD patients may reflect concomitant MPN.An association between hematological cancers and inflammatory bowel disease (IBD) has previously been suggested, but the risk of IBD in patients with myeloproliferative neoplasms (MPNs) is unknown. We conducted a nationwide population-based cohort study using Danish registries, to estimate the risk of IBD in individuals diagnosed with essential thrombocythemia, polycythemia vera, myelofibrosis or unclassifiable MPN during 1994–2013. MPN patients were matched 1:10 with sex- and age-matched comparisons. Everyone was followed until a diagnosis of IBD, death/emigration, or 31 December 2013. The risk of IBD overall and according to MPN subtype was calculated using Cox regression and presented as hazard ratios (HRs) with 95% confidence intervals (CI). Of 8207 MPN patients followed for 45,232 person-years, 80 were diagnosed with IBD (61 ulcerative colitis, 19 Crohn’s disease). The rate of IBD per 1000 person-years was 1.8 (95% CI:1.4–2.2) in patients vs. 0.8 (95% CI:0.7–0.8) in comparisons, and the absolute 10-year risk of IBD was 0.8% (95% CI:0.6–1.0) in patients vs. 0.4% (95% CI:0.4–0.5) in comparisons. The HR of IBD was 2.4 (95% CI:2.1–2.9) with similar HRs for ulcerative colitis and Crohn’s disease. MPN subtype risks varied from 2.1 (95% CI:1.6–2.7) to 2.8 (95% CI:2.1–3.7). Our unselected cohort study showed a more than 2-fold increased risk of IBD in MPN patients.

Circulating cell-free DNA improves the molecular characterisation of Ph-negative myeloproliferative neoplasms.

Genetic studies in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) are essential to establish the correct diagnosis and to optimise their management. Recently, it has been demonstrated that it is possible to detect molecular alterations analysing cell-free DNA (cfDNA) in plasma samples, which is known as liquid biopsy. We have assessed the molecular profile of a cohort of 107 MPN patients [33 polycythaemia vera (PV), 56 essential thrombocythaemia (ET), 14 primary myelofibrosis (PMF) and 4 unclassifiable MPN] by next-generation sequencing (NGS) using cfDNA and paired granulocyte DNA. A high concentration of cfDNA in plasma was observed in patients with high molecular complexity, in MPL-mutated cases, and in PMF patients. Targeted sequencing of cfDNA showed a comparable mutational profile (100% accuracy) to the one obtained in granulocytic DNA and a strong correlation was observed between the variant allele frequency (VAF) of gene mutations in both DNA sources. The median VAF detected in cfDNA (29·0%; range: 0·95-91·73%) was significantly higher than the VAF detected in granulocytes (median 25·2%; range: 0·10-95·5%), especially for MPL mutations (44·3% vs. 22·5%). In conclusion, our data support the use of cfDNA as a fast, sensitive and accurate strategy for performing molecular characterisation of MPN patients.

MERGE: A Multinational, Multicenter Observational Registry for Myeloproliferative Neoplasms in Asia, including Middle East, Turkey, and Algeria.

Philadelphia chromosome‐negative (Ph−) myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal disorders of the bone marrow, and are associated with a high disease burden, reduced quality of life (QOL), and shortened survival. This multinational, multicenter, non‐interventional registry “MERGE” was initiated with an objective to collect data on the epidemiological indices of classical Ph‐MPNs, existing treatment patterns, and impact of MPNs on health‐related QOL in various countries/regions in Asia, including the Middle East, Turkey, and Algeria. Of the 884 eligible patients with MPNs, 169 had myelofibrosis (MF), 301 had polycythemia vera (PV), 373 had essential thrombocythemia (ET), and 41 had unclassified MPNs. The median age was 58 years (range, 47‐66 years), and 50% of patients were males. The prevalence and incidence of MPNs were estimated to be 57‐81 and 12‐15 per 100 000 hospital patients per year over the last 4 years, respectively, in these countries. Total symptom score (mean [standard deviation; SD]) at baseline was highest in patients with MF (23.5 [17.47]) compared with patients with ET (14.6 [14.26]) and PV (16.6 [14.84]). Patients with ET had a lower mean (SD) number of inpatient visits (0.9 [0.77] days), and patients with MF had more outpatient visits (5.2 [3.17] days) on an average, compared with the entire MPN group. The study showed that patients with MPNs have a severe disease burden and reduced QOL. A discordance between physician and patient perception of symptom assessment was observed in this study (International clinical trials registry ID: CTRI/2014/05/004598).

Outcome of allogeneic haematopoietic stem cell transplantation in myeloproliferative neoplasm, unclassifiable: a retrospective study by the Chronic Malignancies Working Party of the EBMT.

Myeloproliferative Neoplasm (MPN), unclassifiable (MPN-U) is a heterogeneous disease with regards to both clinical phenotype and disease course. Patients may initially be asymptomatic orpresent 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 notwell defined. We hereby report on the largest retrospective study of patients with MPN-U undergoing allo-HCT, highlighting the potentially curative role and providingclinicians with robust engraftment, GvHD and outcome data to facilitate patient discussion.

Outcome of Allogeneic Haematopoietic Stem Cell Transplantation in Myeloproliferative Neoplasms-Unclassifiable: A Retrospective Study By the Chronic Malignancies Working Party of EBMT

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 &lt;5% of all MPN when stringent World Health Organisation (WHO) 2016 classification is followed. No well-defined treatment algorithm exists and therapeutic approaches vary, ranging from observation alone, cytoreductive or experimental agents, high dose chemotherapy and in some instances allogeneic Haematopoietic Cell Transplantation (allo-HCT). Outcome analysis for this allo-HCT cohort is lacking.We hereby report on a retrospective, multicentre, EBMT-registry based study of adult patients with a confirmed diagnosis of MPN-U according to updated WHO 2016 criteria that received an allo-HCT. 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.

The Frequency of Calr and MPL Gene Mutations in Jak2 V617F - Positive Chronic Myeloproliferative Neoplasms in Russia

Background. Ph-negative chronic myeloproliferative neoplasms (MPNs) are characterized by proliferation of one or more myeloid cell lineages and include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). Somatic Jak2, MPL and CALR gene mutations are responsible for more than 90% of NPM cases. These mutations affect sequential stages of prolipherative signal transduction and therefore after the emergence of one type of mutation another types basically should not have any selective advantages for clonal expansion. However, simultaneous findings of these mutations have been reported by different investigators in up to 10% of MPN cases. Aim. To evaluate frequencies of MPL and CALR mutations in Jak2 positive MPN cases for Russian cohort of patients. Methods. Archival DNA samples from MPN patients followed up at the National Research Center for Hematology between 2014 and 2019 included into retrospective study. DNAs and RNAs were extracted from blood using reagent kit from Interlabservice (Russia). Jak2 V617F mutation was quantified by real-time PCR kit from Syntol (Russia) according to manufacturers instructions. CALR exon 9 deletions/insertions were analyzed by fragment analysis (sensitivity &gt;= 3%). MPL W515L/K mutations were assessed by in-house allele specific PCR. All cases were tested for phi-negativity using BCR-ABl p210 PCR kit from Interlabservice (Russia). Results. At least one of the mutations was found in 3863 cases. Jak2 V617F mutation - 3385 cases (87.6%); CALR insertion or deletion - 471 case (12.2%); MPLW515L/K mutation - 31 case (0.8%). We have found 28 cases (0.7%) with Jak2 and CALR mutations combined and 3 cases (0.1%) with Jak2 and MPL mutations in the cohort studied. Matched measures were obtained at least twice at different time points during the course of disease for these cases. No cases with simultaneous CALR and MPL mutations were detected. In 23 from 31 (74%) cases with combined mutations Jak2 V617F allele burden was lower than 3%. Among cases with combined mutations 5 were diagnosed with PV, 8 - with ET, 8 - with PMF and 10 with unclassified MPN. No correlations between diagnosis, mutation combination or allele burden were found. Conclusions. Based on the data, obtained on retrospective DNA samples we cannot state whether combined mutations are present in different clones of myeloid cells or in one. Indirectly, the fact that more often mutations in CALR and MPL genes were found in the cases with a low Jak2 V617F allele burden may indicate that additional mutations occur in the "competing" cell clone. Further prospective studies with mutation monitoring over the therapy are required to assess the value of combined mutations for MPN pathogenesis. Disclosures No relevant conflicts of interest to declare.

CSF3R Mutations Are Exceedingly Rare Genetic Events Associated with Inferior Survival and Sensitivity to Ruxolitinib across Myeloid Malignancies

BACKGROUND: CSF3R mutations are rare genetic events that have been associated with clinical response to the kinase inhibitors ruxolitinib and dasatinib according to the location and type of mutation observed. Although it has been reported that CSF3R mutations are exclusively associated with chronic neutrophil leukemia (CNL), the clinical relevance and response to therapy across the breadth of myeloid neoplasms is largely unknown. To address this, we report the first case series of CSF3R mutations across a large cohort of myeloid neoplasms. METHODS: This study was approved by scientific and ethical review boards. Cases were profiled for all exons of CSF3R utilizing a CLIA-certified 54 gene myeloid Truseq panel or a commercial panel covering over 400 genes. All cases were sequenced on an Illumina instrument and had a target read depth of 200X and a variant allele frequency cut-off of 5%. Reads were aligned with Novoalign version 3.04.04 and variants called using Varscan version 2.3.6. Detected CSF3R variants were filtered through an analytic pipeline to include only those that have been previously reported as somatic and resulting in activated signaling. Clinical variables were abstracted from the medical record and analyzed using GraphPad Prism and SPSS. Kaplan-Meier curves were utilized to estimate overall survival. All cases were centrally reviewed by two expert hematopathologists. RESULTS: Between April of 2014 and January of 2019, a total of 6182 patients with myeloid neoplasms were subjected to next generation sequencing (NGS) testing and only 18 (0.29%) harbored somatic activating CSF3R mutations. The CSF3R variants observed included T618I in 12 cases, T640N in 2 cases, T615A in 1 case and truncating mutations in 3 cases. CSF3R mutations were seen at diagnosis in 89% (16) of cases. The median age of CSF3R mutated cases was 77 years old (range 32-87 years), and 72% were male. Most cases were pathologically consistent with CNL (44.4%, 8 cases) but two cases were pathologically consistent with chronic myelomonocytic leukemia, one with myelodysplastic syndrome (MDS), one with myeloproliferative neoplasm unclassifiable (MPN-U), and one with MDS/MPN-U. Five patients were diagnosed with acute myeloid leukemia. Most patients were thrombocytopenic with a median platelet count of 69 x103 cells/dL (range 19-428 x103 cells/dL) and anemic with a median Hgb of 9.5 g/dL (range 7.7-14.1). Splenomegaly was observed in four cases (23.5%) by physical exam. The vast majority had normal cytogenetics (94.1%, 16 cases), and the most commonly co-mutated genes were ASXL1 (11 cases), TET2 (11 cases) and SRSF2 (7 cases).The median overall survival of CSF3R mutated cases was 13.8 months. Seven cases were treated with ruxolitinib, 5 of which harbored T618I mutations. When considering bone marrow myeloblast reduction, improvement in transfusion requirements, cytoreduction, improvement in splenomegaly, or improvement in constitutional symptoms, 100% of cases derived clinical benefit from ruxolitinib. This included two patients with clinically meaningful hematologic improvements as well as improvement in splenomegaly in 2 out of 3 patients with baseline splenomegaly. Further, one patient with serial NGS demonstrated CSF3R mutation clearance after 5 months of ruxolitinib therapy. The median overall survival was improved in ruxolitinib treated cases but did not reach statistical significance (16.5 vs. 10.9 months, p=0.27). CONCLUSIONS: To our knowledge, this represents the largest collection of ruxolitinib treated CSF3R mutant myeloid neoplasms reported. Although enriched in CNL, CSF3R can occur in other myeloid neoplasms to include CMML and their overall prognosis is poor. Our data suggest that ruxolitinib should be considered in patients with membrane proximal CSF3R mutations. Disclosures List: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lancet:Agios Pharmaceuticals: Consultancy; Daiichi-Sankyo: Consultancy; Pfizer: Consultancy; Jazz Pharmaceuticals: Consultancy. Sallman:Celyad: Membership on an entity's Board of Directors or advisory committees. Komrokji:celgene: Consultancy; DSI: Consultancy; Agios: Consultancy; Novartis: Speakers Bureau; JAZZ: Speakers Bureau; Incyte: Consultancy; JAZZ: Consultancy; pfizer: Consultancy. Pinilla Ibarz:Sanofi: Speakers Bureau; Bayer: Speakers Bureau; TG Therapeutics: Consultancy; Teva: Consultancy; Janssen: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Takeda: Consultancy, Speakers Bureau. Kuykendall:Abbvie: Honoraria; Janssen: Consultancy; Incyte: Honoraria, Speakers Bureau; Celgene: Honoraria. OffLabel Disclosure: Ruxolitinib for the treatment of CSF3R mutated myeloid malignancies.

PB2231 THE MYELOPROLIFERATIVE NEOPLASMS UNCLASSIFIABLE. OUR EXPERIENCE

Background:According to the WHO classification, the designation of myeloproliferative neoplasms unclassifiable (MPN‐U) should be used for cases with clinical, morphologic, and molecular features of MPN failing to meet the diagnostic criteria of a specific entity. Reported incidence of MPN‐U varies significantly in different studies with a range up to &gt; 20%. However, most studies show an incidence of 10–15% or even less. When the 2016 WHO criteria have been applied, the incidence is reduced to &lt;5%.Aims:In this report we study the clinical and laboratory characteristics of 31 consecutive cases of unclassifiable myeloproliferative disease afferent to the center for myeloproliferative diseases of our Hematology Unit.Methods:From 2010 to 2018 our center has collected 508 cases of Philadelphia‐negative Myeloproliferative Neoplasms (MPNs). Data from these patients were collected in a specific database and analysed with simple statistic tools.Results:Among these 508 patients, 31 (6.2%) had a diagnosis of MPN‐U, 16 male and 14 female. Median age at diagnosis was 60.9 years. 22/31 (70.9%) were JAK2 V617F positive, 3/31 were CALR mutated (0.96%), 2/31 (0.64%) MPL mutated and 6/31 (19.3%) resulted as triple negative (TN) for driver mutations. Data from the other groups of MPNs (PV, ET, overtMF and preMF) were analised as well and compared to the ones from the MPN‐U group.Summary/Conclusion:Chronic myeloproliferative diseases unclassifiable (MPN‐U) represent the 6.2% of the cases relating to our center. No significant difference at diagnosis has been highlighted regarding sex, age and mutational status between MPN‐U and MPN classified according to WHO 2016. The exact incidence of MPN‐U is unknown. It is probable that frequency varies significantly according to the experience of the diagnostician and the specific classification system and criteria used. It is possible that careful use of the WHO 2016 classification may significantly reduce the frequency of MPN‐U.

T(3;8)(q26.2;q24) Often Leads to MECOM/MYC Rearrangement and Is Commonly Associated with Therapy-Related Myeloid Neoplasms and/or Disease Progression

t(3;8)(q26.2;q24) is a rare recurrent cytogenetic abnormality that is associated with myeloid neoplasms. Of 20 patients with t(3;8)(q26.2,q24), 8 had therapy-related acute myeloid leukemia (AML), 3 therapy-related myelodysplastic syndrome, 4 blast phase of chronic myeloid leukemia, 1 relapsed AML, 1 AML transformed from chronic myelomonocytic leukemia, 1 blast phase of an unclassifiable myeloproliferative neoplasm, 1 de novo myelodysplastic syndrome, and 1 de novo AML. Nineteen patients presented with cytopenia. Multilineage dysplasia was observed in 16/18 patients, and megakaryocytes were markedly decreased in 11/20 patients. Blasts showed a primitive myeloid immunophenotype in 17 patients, negative for myeloperoxidasein in 14/17, and aberrant CD7 expression in 5/17 patients. Fluorescence in situ hybridization showed MECOM rearrangement in 18/19 and MYC in 16/18 patients. Myc was shown to be expressed in all 14 cases assessed. Gene mutation testing was performed in 14 patients, and 7 showed at least one mutation including ASXL1 (2/6), TET2 (2/6), SRSF2 (2/6), and NRAS (2/13). At last clinical follow-up, 18 patients died and 2 were alive with persistent disease, with a median survival of 6 months. The authors conclude that t(3;8)(q26.2;q24) often leads to MECOM and MYC rearrangement, occurs predominantly in therapy-related myeloid neoplasms or at disease progression, and shares some similarities with myeloid neoplasms associated with inv(3)/GATA2-MECOM. Patients with myeloid neoplasms associated with t(3;8)(q26.2;q24) have a dismal outcome.

The epidemiology and clinical characteristics of myeloproliferative neoplasms in Malaysia

BackgroundThe evolution of molecular studies in myeloproliferative neoplasms (MPN) has enlightened us the understanding of this complex disease consisting of polycythaemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The epidemiology is well described in the western world but not in Asian countries like Malaysia.Materials and methodsThis retrospective national registry of MPN was conducted from year 2009 to 2015 in Malaysia.ResultsA total of 1010 patients were registered over a period of 5 years. The mean age was 54 years with male predominance. The ethnic distribution revealed that Chinese had a relatively high weighted incidence proportion (43.2%), followed by Indian (23.8%), Malay (15.8%) and other ethnic groups (17.2%). The types of MPN reported were 40.4% of ET (n = 408), 38.1% of PV (n = 385), 9.2% of PMF (n = 93), 3.1% of hypereosinophilic syndrome (HES) (n = 31) and 7.9% of unclassifiable MPN (MPN-U) (n = 80). Splenomegaly was only palpable clinically in 32.2% of patients. The positive JAK2 V617F mutation was present in 644 patients with 46.6% in PV, 36.0% in ET, 9.0% in PMF, and 7.4% in MPN-U, and had significantly lower haemoglobin (p < 0.001), haematocrit (p < 0.001) and white blood cells (WBC) (p < 0.001) than those with negative mutation. Significant differences in platelet and WBC count were detected in ethnic groups and MPN sub-types. There were more arterial thrombosis events seen in those with JAK2 V617F mutation as compared to venous thrombosis events (23.1% vs 4.4%). The bleeding rate was only 6.6%. Among the risk factors, previous thrombosis, old age (≥ 60 years) and hypertension were significantly correlated to positive JAK2 V617F mutation. The arterial thrombosis event is associated with higher presenting HB, HCT and PLT while the bleeding event is associated with lower presenting HB, HCT but higher PLT. The presence of JAK2 V617F mutation is associated with higher risk of arterial thrombosis.ConclusionChinese ethnicity is associated with higher rates of MPN. The history of thrombosis, age ≥ 60 years and hypertension are risk factors that can be correlated to JAK2 V617F mutation. This study is instrumental for policy makers to ensure preventive strategies can be implemented in future.

Myeloproliferative Neoplasms in Patients below 25 Years Old at Diagnosis: A Retrospective International Cooperative Work

Myeloproliferative neoplasms (MPN) are most common in old people (>60 years) and are rarely identified in children and young adults where information about complication rates and long-term data are lacking. To improve our knowledge, we retrospectively collected cases of young patients diagnosed with MPN before 25 years of age and analysed data of their disease to date, including vascular events and disease evolution.Data were collected in 29 hospital centres from 12 countries. Between 1971 and 2018, 335 young patients were diagnosed for an MPN before the age of 25. They were mostly females (n=246; 73.4%) with a median age of 20.3 years at diagnosis (2.5 months-25 years). Essential thrombocythemia was diagnosed in 234 patients (69.8%), polycythemia vera in 60 (17.9%) and myelofibrosis or unclassified MPN in 41 (12.3%).Most of the diagnoses were made following a coincidental blood count analysis (n=75; 51%) some based on symptoms (n=57; 38.8%) or thrombotic events (n=15; 10.2%). In terms of complications before or at diagnosis, 31 (9.3%) patients experienced thrombosis, mostly venous (75%) and 13 (3.9%) had hemorrhage. At diagnosis, the median leukocyte count was 9x109/l (range: 3-22.8), median hemoglobin count 140 g/l (65-220) and median platelet count 900x109/l (99-3290). To assess the diagnosis, 158 patients (47.2%) had had bone marrow aspirates and 214 (63.9%) a bone marrow biopsy. Mutational status was available in 319 (90%) cases: 194 (60.8%) were JAK2V617F positive, 48 (15%) had a calreticulin mutation, 76 (23.8%) were triple-negative and 1 patient had MPL mutation.The median follow-up of the cohort was 7.7 years (0-46.8) with 134 patients (40%) having follow-up for more than 10 years. 81 female patients (32.9%) experienced pregnancies. During this period, 295 patients (88%) received at least one drug for their MPN: 254 patients (77.2%) received antithrombotic drug and 222 patients (66.5%) a cytoreductive drug. As first line of treatment, hydroxycarbamide was given to 111 patients (50%) whereas anagrelide was given to 56 patients (25.2%) and interferon to 50 (22.5%).During the follow-up, 97 patients (29%) experienced at least one complication. In terms of cardiovascular events, 38 (11.3%) patients experienced thromboses with 50 events in total (recurrences in 12 cases), including 33 venous events (66%) of which 15 were localized in the splanchnic territory (45.5%). Hemorrhagic events were recorded in 34 cases (10.1%). During the follow-up, 39 patients (11.6%) have evolved: 11 from ET to PV (28.2%), 26 into MF (66.7%) and 2 into AML (5.1%). All evolutions were exclusive: one event per patient. At the time of the analysis, 66 patients (19.7%) were declared as lost of follow up and 4 were dead (1.2%).This is the largest cohort of patients aged below 25 years at the time of diagnosis demonstrates that despite their youth most of them (88%) received drug(s) for the management of their MPN. There was a high incidence of complications (29%), with vascular events and disease evolution occurring at equal frequency although death was uncommon (1.2%). Rates of events were disease evolution: 1.51/100pts/y; thromboses: 1.47 and hemorrhages: 1.32. No specific national or international guidance exists for MPN patients of this age; but our data suggest that these are not benign conditions and patients need to be carefully followed and treated. [Display omitted] DisclosuresKiladjian:Celgene: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding. Giraudier:Novartis: Research Funding. Griesshammer:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Harrison:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria; Gilead: Honoraria, Speakers Bureau; CTI BioPharma: Consultancy, Honoraria.

Impact of Myeloproliferative Neoplasms (MPNs) on Health-Related Quality of Life (HRQOL) and Medical Resource Utilization: Results from the MERGE Registry

BackgroundThe Philadelphia chromosome−negative classical MPNs (myelofibrosis [MF], polycythemia vera [PV], and essential thrombocythemia [ET]) are associated with a pronounced symptom burden, including fatigue, night sweats, itching, and inactivity that may affect patients' HRQOL. There is a limited real-world evidence from many of the Asian countries, including Middle East, regarding the impact of MPNs on HRQOL, or the economic burden associated with these diseases. MERGE is a multinational, multicenter, nonintervention study conducted in adult patients with MPNs in Asia, including Middle East, Turkey, and Algeria. The present analysis evaluated the impact of MPNs on HRQOL of patients from MERGE and explored the association of HRQOL with the clinical outcomes and resource utilization.MethodThe MERGE registry included patients with MPN diagnosed as per the World Health Organization 2008 criteria. Patients were planned to be followed up for 2 years (5 visits over the course of study). MPN Symptom Assessment Form Total Symptom Score (MPNSAF TSS) was administered during the routine biannual follow-up visits to assess the HRQOL. MPNSAF TSS score was calculated only for patients who completed at least 6 of the 10 items on the MPNSAF TSS questionnaire. The level of inter-rater agreement between physicians and patients on the proportion of symptomatic patients was assessed through Cohen's Kappa coefficient.Further, an ANCOVA (Analysis of covariance) model was applied to estimate the influence of the baseline variables (age, sex, weight, height, family history of MPNs, comorbidities, time to initial MPNs diagnosis, type of MPN initial diagnosis, baseline hemoglobin and platelet count, Eastern Cooperative Oncology Group Performance Status [ECOG PS], and time since diagnosis to treatment initiation) on the TSS score. Variables with univariate P-value < 0.20 were included in the multivariate model.Furthermore, medical resource utilization was assessed by evaluating the inpatient and outpatient visits, hospice care, emergency room visits, and day care.ResultsOf the 884 eligible patients with MPNs, 169 had MF, 301 had PV, 373 had ET, and 41 had unclassified MPN. During the study, 64% of patients received hydroxyurea, 15% interferon, 15% JAK inhibitors, and 10% anagrelide either alone or in combination. At baseline, the proportion of patients presenting at least 1 of the symptoms was higher in the MF group (96.4%), compared to the total MPN patients (91.8%). In addition, the TSS (mean [SD]) at baseline was highest in the patients with MF (23.5 [17.47]) as compared to patients with ET (14.6 [14.26]) and PV (16.6 [14.84]). During the study duration and follow-up, the TSS remained approximately constant at subsequent visits.Physicians reported a lower proportion of symptomatic patients than the proportion self-reported by patients, although, there was better agreement between physicians and patients for pruritus and night sweats (Kappa, 0.61-0.80) (Table 1) than for other symptoms (Kappa, 0.41-0.60). Across MPN subtypes, inter-rater agreement was lowest for patients with MF compared to patients with ET or PV.In a multivariate adjusted mixed effect regression model, female gender, type of MPN (MF), presence of comorbidities, lower baseline hemoglobin were independently and positively associated with the symptom score values.Overall, 24.3% of the patients had at least 1 inpatient visit, with a mean duration of 11.1 days. Outpatient visits were the most commonly observed healthcare resource used (95.5%), without remarkable change during the follow-up period. Patients with ET had a lower mean number of inpatient visits (mean [SD]: 0.9 [0.77] days), and patients with MF had more outpatient visits (mean [SD]: 5.2 [3.17] visit) on an average, compared to the entire MPN group.ConclusionDespite being on treatment, patients with MPN in MERGE had substantial symptom burden, which did not change over the course of the study. A discordance between physician and patient perception of symptom assessment was seen in this study, indicating that in addition to spleen and hematological investigations, a more systematic assessment such as the use of MPNSAF TSS could help to better evaluate patients' symptoms and understand the disease and its treatment burden. [Display omitted] DisclosuresTaher:Celgene Corp.: Research Funding; Ionis Pharmaceuticals: Consultancy; Protagonist Therapeutics: Consultancy; La Jolla Pharmaceutical: Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Yassin:Novartis: Research Funding. Rippin:Employee of IQVIA - doing consultancy for Novartis: Consultancy. Sadek:Novartis Pharmaceutical Corporation: Employment. Siddiqui:Novartis Pharma AG: Employment, Equity Ownership. Wong:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Epidemiology of Patients with Classical Philadelphia-Chromosome Negative Myeloproliferative Neoplasms at a Single Academic Medical Center in Singapore

Introduction:Myeloproliferative Neoplasms (MPNs) represents a disorder that involves abnormal proliferation of cells originating from the myeloid line. The proliferation of these cells can lead to complications that are at times fatal. Despite its potential to cause life threatening complications, there is little data on this disease in Southeast Asia.As Singapore is a multiracial country in Southeast Asia, there may be some disease characteristics exclusive to patients here due to its unique population composition. The data from this Southeast Asian cohort would be useful to determine disease homogeneity in Asian countries.Methods:A retrospective review of the MPN database from National University Hospital, Singapore (NUHS) revealed 320 patients who were clinically diagnosed with MPN from 2008 to 2017. This data included patients with Essential Thrombocythemia (ET), Polycythemia Rubra Vera (PRV), Primary Myelofibrosis (PMF), Myeloproliferative Neoplasm, unclassifiable (MPN-U) and Chronic Eosinophilic Leukemia (CEL) (Figure 1A) as per the 2017 WHO classification. For this analysis, we included only the classical Philadelphia chromosome negative MPN and focused on the epidemiology, transformation and overall survival rate.Results:There was a slight male predominance with a male to female ratio of 1.3:1. The ethnic groups within this cohort consisted of 65.8% ethnic Chinese, 20.7% Malay, 5.5% Indian and the rest were made up of other ethnic groups within the region such as Eurasians, Thai, Filipinos, Burmese, Indonesians, Bangladeshi, Vietnamese and Arabian patients.The mean age at diagnosis for this group was 60.5. The mean age was 59.2 years for ET, 61.2 for PRV and the mean age of PMF was the oldest at 63.8. The mean age of diagnosis for ET and PMF patients in our cohort was slightly older compared to the Korean cohort (55.4 and 59.5 years) (Byun, et al., 2016).The majority of this cohort was made up of ET patients (53.1%) followed by PRV (35.3%) and PMF (11.6%).77.5% of these patients were JAK2 V617F mutation (JAK2) positive. The percentage of patients who were JAK2 positive for ET, PRV and PMF were 69.2%, 96.9% and 56.3% respectively. The percentage of JAK2 positive patients for the three subtypes were higher in our local population compared to the Chinese and Japanese cohorts.Only 120 patients were tested for Calreticulin Exon 9 (CALR) mutations as this molecular test was only available in our institution from 2015 onwards. ET patients make up 68.4% of CALR positive patients. It was noted that CALR positive patients had comparatively higher mean platelet counts of 925.2 than CALR negative patients with mean platelet counts of 691.7. This phenomenon is seen in both CALR positive ET and CALR positive MF patients.In the 10-year period, 25 patients were lost to follow up and 8 patients transferred their care to another institution. Overall, 27 patients were deceased, with a mean survival of 3.5 years. The death-to-case ratio was 11.5 per 100 cases. The death-to-case ratio for ET, PRV and PMF is 6.1 per 100, 8.2 per 100 and 31.3 per 100 respectively.During this period, only 6 patients had transformation. Three patients progressed to post-ET myelofibrosis and 3 had leukemic transformation. Those who had leukemic transformation were initially diagnosed with PRV (1 patient) and PMF (2 patients). All patients who had leukemic transformation were deceased and had a mean survival of 1.4 years from the transformation event.Conclusion:Whilst there were some observable differences between our data and existing Asian data, there is still insufficient information to determine disease homogeneity. This is partly due to the rapid growth of molecular knowledge in this field and the regular revision of the WHO diagnostic criteria of MPNs over the last decade or so. There needs to be coordinated efforts within the region to ensure that our patients have equal access to these diagnostic platforms and that they receive an accurate diagnosis. DisclosuresChng:Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Aslan: Research Funding; Merck: Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel, accommodation, expenses.

The 2014 BCSH criteria and the 2016 WHO criteria for essential thrombocythemia: A comparison in a large-scale cohort.

There are currently 2 representative diagnostic criteria for essential thrombocythemia (ET), the 2014 British Committee for Standards in Hematology Guidelines (BCSH) criteria and the 2016 World Health Organization (WHO) criteria. We compare and discuss the advantages and disadvantages of the 2 criteria. We applied the 2 criteria to 403 patients with thrombocytosis and suspected myeloproliferative neoplasms (MPN) and compared patient populations. The BCSH criteria diagnosed ET in 279 patients (BCSH-ET) whereas the WHO criteria diagnosed ET in 203 patients (WHO-ET). There were 83 patients diagnosable only by the BCSH criteria (BCSH-only-ET), of which under the WHO classification, 69 patients fell under the category of MPN, unclassifiable (MPN-u), 12 patients were PMF, prefibrotic/early stage (pre-PMF), and 2 patients were polycythemia vera. Patient characteristics such as age, hemoglobin, hematocrit, platelet counts, lactate dehydrogenase levels, JAK2V617F allele burdens, prevalence of myelofibrosis and splenomegaly, and frequencies of thrombotic events and treatment did not differ between WHO-ET and BCSH-only-ET, but BCSH-only-ET patients showed higher WBC counts and higher JAK2V617F mutation frequencies. The BCSH criteria diagnosed ET in a broader range of patients encompassing a significant number of patients who would otherwise be diagnosed as pre-PMF or MPN-u.

Molecular genetics of BCR-ABL1 negative myeloproliferative neoplasms in India.

Over the past decade, we have moved on from a predominantly morphological and clinical classification of myeloproliferative neoplasms (MPN) to a more evolved classification that accounts for the molecular heterogeneity that is unique to this subgroup of hematological malignancies. This usually incorporates mutations in Janus kinase 2 (JAK2), MPL, and calreticulin (CALR) genes. In this manuscript, we report the frequency of these mutations in a cohort of Indian patients at a tertiary cancer center. One hundred and thirty cases of MPN were included in this study. These cases were diagnosed and classified based on the World Health Organization 2008 criteria. JAK2 and MPL mutations were detected using high sensitivity allele-specific polymerase chain reaction using fluorescent labeled primers followed by capillary electrophoresis. A subset of JAK2 and CALR mutations were assessed using a fragment length assay. Among the MPN, we had 20 cases of polycythemia vera (PV), 34 cases of essential thrombocythemia (ET), and 59 of myelofibrosis (MF). JAK2, MPL, and CALR mutations were mutually exclusive of each other. Seventeen cases were categorized as MPN unclassifiable (MPN-U). JAK2p.V617F and MPL mutations were present in 60% (78 of 130) and 5.3% (7 of 130) of all MPN. All the PV cases harbored the JAK2 p.V617F mutation. A total of 23.8% (31 of 130) of patients harbored CALR mutations. CALR exon 9 mutations were detected in 60.8% (14 of 23) and 50% (5 of 10) of JAK2 and MPL negative MF and ET cases, respectively. MPN-U cases included three JAK2 p.V617F positive, two MPL p.W515 L, and 12 CALR positive cases. Ten different types of CALR indels (8 deletions and 2 insertions) were detected of which Type I and Type II mutations were the most common, occurring at a frequency of 45.1% (14 of 31) and 22.5% (7 of 31), respectively. We report frequencies of JAK2 p. V617F, MPL exon 10 and CALR mutations in 130 patients similar to those reported in western literature. These mutations carry not only diagnostic but also prognostic relevance.

Abstract 2452: Detailed genomic characterization of CNL/aCML/MPN-U/CMML reveals disease subgroups that may benefit from rationally-designed combination therapies

Abstract Purpose: Chronic neutrophilic leukemia (CNL), chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia (aCML), and unclassified myeloproliferative neoplasms (MPN-U) are a group of heterogeneous disorders belonging to rare entities of myeloproliferative or myelodysplastic/myeloproliferative (MDS/MPN) syndromes. Due to lack of specific molecular markers and the limited understanding of pathogenesis, the treatment of these diseases remains empirical, resulting in poor outcomes. Recently, recurrent mutations in ASXL1, TET2, SRSF2 and cell signaling genes have been identified in these diseases. In this study we aim to analyze the co-occurrence patterns of these gene mutations, as well as the association of different mutations with disease subtypes and treatment outcomes. Methods and results: We performed whole exome sequence and RNA-Seq on primary patient samples. Consistent with previous studies, high frequencies of ASXL1, SRSF2, TET2, SETBP1 and signaling pathway mutations were observed; whereas mutations of MPL, CEBPa, IDH1/2, and TP53 were rare. Further variant allelic frequency analysis demonstrated that mutations of the chromatin modifiers, epigenetic markers and splicing factors are mostly present in the major clones indicating early acquisition of these mutations. In addition, ASXL1/2, splicing factor and signaling pathway mutations co-occur in around 45% of all patients with these mutations, indicating that they drive these diseases in a cooperative manner. RNA-seq analysis demonstrated two major gene expression clusters with high levels of either RAS or JAK-STAT signaling alterations respectively, indicating a potential need for distinct therapeutic targeting of specific subgroups of these diseases. In addition, we observed that 17% of patients have more than one signaling pathway mutation, possibly in distinct subclones, providing rationale for drug combination treatment. Furthermore, we observed that mutations related to RAS signaling pathway are prevalent in CMML; CSF3R and JAK2 mutations are enriched in CNL; whereas, RAS and JAK-STAT pathway double mutations are more frequent in aCML. Similar incidence of ASXL1, splicing factor and epidemics mutations are observed across all these diseases. Conclusions: CNL/aCML/MPN-U/CMML is a group of heterogeneous diseases associated with chromatin modifier, epigenetic, splicing factor and signaling pathway mutations in concomitant manner. We propose future studies of rational drug combinations with agents, targeting epigenetic and splicing factors, together with the appropriate signaling pathway inhibitors. Our study represents a large-scale comprehensive genomic analysis of these diseases, which reveals novel insight into patterns of mutation co-occurrence which could translate into new treatment paradigms for these difficult to treat hematologic malignancies. Citation Format: Haijiao Zhang, Beth Wilmot, Daniel Bottomly, Libbey White, Erik Segerdell, Shannon K. McWeeney, Vishesh Khanna, Angela Rofelty, Sophie Means, Brian Junio, Samantha Savage, Emily Stevens, Kim-Hien Dao, Julia E. Maxson, Jeffrey W. Tyner. Detailed genomic characterization of CNL/aCML/MPN-U/CMML reveals disease subgroups that may benefit from rationally-designed combination therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2452. doi:10.1158/1538-7445.AM2017-2452