Myeloproliferative Neoplasms Patients Research Articles

The characteristics of CALR mutations in myeloproliferative neoplasms: a clinical experience from a tertiary care center in Qatar and a literature review

ABSTRACT Background Myeloproliferative neoplasms (MPNs) are hematological disorders characterized by abnormal production of myeloid cells due to genetic mutations. Since 2013, researchers have identified somatic mutations in the Calreticulin (CALR) gene, primarily insertions or deletions, in two Philadelphia chromosome-negative MPNs; essential thrombocytosis (ET) and primary myelofibrosis (PMF), and occasionally in chronic myelomonocytic leukemia (CMML). This study aims to identify the various types of CALR mutations and their impact on CALR-positive MPN patients’ clinical manifestations and outcomes. Methods A single-center retrospective study was conducted. The data was collected from pre-existing records. The study was carried out on Philadelphia-negative MPN patients who were being followed up on at the NCCCR (National Center for Cancer Care and Research) to assess the clinical manifestation and outcome of disease treatment. All patients included, were followed in our center between January 1, 2008, and November 20, 2021. Results A total of 50 patients with CALR-positive MPN were reviewed with a median follow-up of three years (1–11). This cohort included 31 (62%) patients with ET, 10 (20%) patients with PMF, and 9 (18%) patients with prefibrotic myelofibrosis (pre-MF). The study involved 38 (76%) male and 12 (24%) female patients. There were 16 (32%) patients diagnosed before the age of 40, 24 (48%) patients diagnosed between the ages of 40 and 60; and 10 (20%) patients diagnosed after the age of 60. Molecular analysis showed 24 (48%) patients with CALR type 1, 21 (42%) patients with CALR type 2, and 5 (10%) patients with none Type 1, none Type 2 CALR mutations. Two patients have double mutations; 1(2%) with none Type 1, none Type 2 CALR and JAK2 mutations, and 1(2%) with CALR type 1 and MPL mutations. The thrombotic events were 3 (6%) venous thromboembolisms, 3 (6%) abdominal veins thromboses, 2 (4%) strokes, and 4 (8%) ischemic cardiac events. Only 4 (8%) patients progressed to Myelofibrosis and were carrying CALR 1 mutations, and 1 (2%) patient progressed to AML with CALR 2 mutation. Conclusion The data shows a significant rise in CALR-positive MPN diagnoses in younger people, emphasizing the need for a better assessment tool to improve disease management and reduce complications.

Immunophenotype of myeloid granulocytes in Chinese patients with BCR::ABL1-negative myeloproliferative neoplasms

Typical BCR::ABL1-negative myeloproliferative neoplasms (MPN) are mainly referred to as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofbrosis (PMF). Granulocytes in MPN patients are involved in their inflammation and form an important part of the pathophysiology of MPN patients. It has been shown that the immunophenotype of granulocytes in MPN patients is altered. We used flow cytometry to explore the immunophenotype of MPN patients and correlate it with clinical parameters. The results showed that PMF patients and PV patients had higher CD15+CD11b+ granulocytes than ET patients and normal controls. When grouped by gene mutation, changes in the granulocyte immunophenotype of MPN patients were independent of the JAK2V617F and CALR mutations. There was no significant heterogeneity in immunophenotype between ET patients and Pre-PMF, and between Overt-PMF and Pre-PMF patients. Granulocytes from some MPN patients showed an abnormal CD13/CD16 phenotype with a significant increase in mature granulocytes on molecular and cytomorphological grounds, and this abnormal pattern occurred significantly more frequently in PMF patients than in ET patients. CD15–CD11b– was negatively correlated with WBC and Hb and positively correlated with DIPSS score, whereas high CD10+ granulocytes were significantly and negatively associated with prognostic system IPSS and DIPSS scores in PMF patients. In conclusion, this study demonstrates the landscape of bone marrow granulocyte immunophenotypes in MPN patients. MPN patients, especially those with PMF, have a significant granulocyte developmental overmaturation phenotype. CD10+ granulocytes may be involved in the prognosis of PMF patients.

A lasso and random forest model using flow cytometry data identifies primary myelofibrosis.

Thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF), prefibrotic/early (pre-PMF), and overt fibrotic PMF (overt PMF) are classical Philadelphia-Negative (Ph-negative) myeloproliferative neoplasms (MPNs). Differentiating between these types based on morphology and molecular markers is challenging. This study aims to clarify the application of flow cytometry in the diagnosis and differential diagnosis of classical MPNs. This study retrospectively analyzed the immunophenotypes, clinical characteristics, and laboratory findings of 211 Ph-negative MPN patients, including ET, PV, pre-PMF, overt PMF, and 47 controls. Compared to ET and PV, PMF differed in white blood cells, hemoglobin, blast cells in the peripheral blood, abnormal karyotype, and WT1 gene expression. PMF also differed from controls in CD34+ cells, granulocyte phenotype, monocyte phenotype, percentage of plasma cells, and dendritic cells. Notably, the PMF group had a significantly lower plasma cell percentage compared with other groups. A lasso and random forest model select five variables (CD34+CD19+cells and CD34+CD38- cells on CD34+cells, CD13dim+CD11b- cells in granulocytes, CD38str+CD19+/-plasma, and CD123+HLA-DR-basophils), which identify PMF with a sensitivity and specificity of 90%. Simultaneously, a classification and regression tree model was constructed using the percentage of CD34+CD38- on CD34+ cells and platelet counts to distinguish between ET and pre-PMF, with accuracies of 94.3% and 83.9%, respectively. Flow immunophenotyping aids in diagnosing PMF and differentiating between ET and PV. It also helps distinguish pre-PMF from ET and guides treatment decisions.

CCN2/CTGF expression does not correlate with fibrosis in myeloproliferative neoplasms, consistent with noncanonical TGF-β signaling driving myelofibrosis

The classical BCR::ABL1-negative myeloproliferative neoplasms (MPN) form a group of bone marrow (BM) diseases with the potential to progress to acute myeloid leukemia or develop marrow fibrosis and subsequent BM failure. The mechanism by which BM fibrosis develops and the factors that drive stromal activation and fibrosis are not well understood. Cellular Communication Network 2 (CCN2), also known as CTGF (Connective Tissue Growth Factor), is a profibrotic matricellular protein functioning as an important driver and biomarker of fibrosis in a wide range of diseases outside the marrow. CCN2 can promote fibrosis directly or by acting as a factor downstream of TGF-β, the latter already known to contribute to myelofibrosis in MPN.To study the possible involvement of CCN2 in BM fibrosis in MPN, we assessed CCN2 protein expression by immunohistochemistry in 75 BM biopsies (55 × MPN and 20 × normal controls). We found variable expression of CCN2 in megakaryocytes with significant overexpression in a subgroup of 7 (13%) MPN cases; 4 of them (3 × essential thrombocytemia and 1 × prefibrotic primary myelofibrosis) showed no fibrosis (MF-0), 2 (1 × post-polycythemic myelofibrosis and 1 × primary myelofibrosis) showed moderate fibrosis (MF-2), and 1 (primary myelofibrosis) severe fibrosis (MF-3). Remarkably, CCN2 expression did not correlate with fibrosis or other disease parameters such as platelet count or thrombovascular events, neither in this subgroup nor in the whole study group. This suggests that in BM of MPN patients other, CCN2-independent pathways (such as noncanonical TGF-β signaling) may be more important for the development of fibrosis.

ADAMTS13, von Willebrand Factor, Platelet Microparticles, Factor VIII, and Impact of Somatic Mutations in the Pathogenesis of Splanchnic Vein Thrombosis Associated with BCR-ABL-Negative Myeloproliferative Neoplasms.

Myeloproliferative neoplasms (MPNs) are often associated with splanchnic vein thrombosis (SVT). Not all the factors involved in the thrombotic tendency are currently known. This study aims to evaluate a possible association between ADAMTS13, von Willebrand factor (VWF), platelet microvesicles (MV), and factor VIII activity (FVIII:C) with thrombotic events in MPN patients. In total, 36 consecutive MPN patients with SVT were enrolled. The MPNs were diagnosed based on clinical characteristics and one or more gene mutations among JAK-2, CALR, and MPL. As controls, 50 randomly selected patients with MPN without thrombosis, 50 patients with deep vein thrombosis without MPNs, and 50 healthy blood donors were evaluated. Complete blood count, ADAMTS13, VWF, MV, and FVIII:C in plasma were measured in all the subjects. The JAK-2 mutation was found in 94% of the patients with SVT, but none were triple-negative for genetic mutations (JAK2 V617F, CALR, MPL, and exon 12). Compared to the normal subjects, in all the MPN patients (with or without SVT), the levels of ADAMTS13 were found to be significantly lower (p < 0.001) and the MV concentrations were significantly higher (p < 0.001). Among the MPN patients, the VWF and FVIII:C levels were significantly higher in the patients with SVT than those without thrombosis (p = 0.007 and p = 0.04, respectively). Splenomegaly was present in 78% of MPN patients with SVT and in 30% of those without SVT (p < 0.001). The ADAMTS13/VWF ratio was reduced in all the patients, but not in the healthy blood donors (p < 0.001). The significant increase in circulating MV, VWF, and FVIII:C in the MPN patients and in the patients with thrombosis supports the role of endothelium damage in promoting thrombotic events. In particular, a significant increase in VWF and FVIII:C levels was found in the MPN patients with SVT.

The personal impact of living with a myeloproliferative neoplasm.

The aim of this study is to gain insight into the physical, psychological and social impact of having a myeloproliferative neoplasm (MPN), a rare type of cancer with an often chronic course. An online survey was conducted among 455 Dutch MPN patients (62.7% female, age M 63) to explore the impact of the disease by measuring the MPN symptom burden (MPN-SAF TSS) and quality of life (QoL) (EORTC QLQ-C30) and its subscales within a hierarchical QoL model. We examined differences in MPN symptom burden and QoL in relation to sociodemographic and disease-related factors. Hierarchical regression analysis was used to explain variances in QoL. Most patients (97%) experienced MPN-related health complaints, with a significantly higher MPN symptom burden in women (M 31.50) compared to men (M 24.10). Regarding to fatigue and cognitive functioning MPN patients suffered more compared to a reference group of other cancers. MPN subtype or type of treatment did not show significant differences in MPN symptom burden or QoL. However, experiencing side effects, complications or comorbidities significantly negatively affected MPN symptom burden and QoL. 48.8% of patients reported that MPN affected their ability to work. The explained variance in overall QoL was 58%, most importantly by disease progression, comorbidities, MPN symptom burden and role, emotional and social functioning. This study revealed that having an MPN has a negative impact on several domains of QoL. Symptom assessment and support should be included in the healthcare management of MPN patients.

Treatment outcome and germline predictive factors of ropeginterferon alpha-2b in myeloproliferative neoplasm patients.

Studies have shown that some single nucleotide polymorphisms (SNPs) could serve as excellent markers in foretelling the treatment outcome of interferon (IFN) in myeloproliferative neoplasms (MPN). However, most work originated from western countries, and data from different ethnic populations have been lacking. To gain insights, targeted sequencing was performed to detect myeloid-associated mutations and SNPs in eight loci across three genes (IFNL4, IFN-γ, and inosine triphosphate pyrophosphatase [ITPA]) to explore their predictive roles in our cohort of 21 ropeginterferon alpha-2b (ROPEG)-treated MPN patients, among whom real-time quantitative PCR was also performed periodically to monitor the JAK2V617F allele burden in 19 JAK2V617F-mutated cases. ELN response criteria were adopted to designate patients as good responders if they achieved complete hematological responses (CHR) within 1 year (CHR1) or attained major molecular responses (MMR), which occurred in 70% and 45% of the patients, respectively. IFNL4 and IFN-γ gene SNPs were infrequent in our population and were thus excluded from further analysis. Two ITPA SNPs rs6051702 A>C and rs1127354 C>A were associated with an inferior CHR1 rate and MMR rate, respectively. The former seemed to be linked to grade 2 or worse hepatotoxicity as well, although the comparison was of borderline significance only (50%, vs. 6.7% in those with common haplotype, p = 0.053). Twelve patients harbored 19 additional somatic mutations in 12 genes, but the trajectory of these mutations varied considerably and was not predictive of any response. Overall, this study provided valuable information on the ethnics- and genetics-based algorithm in the treatment of MPN.

Abstract 263: RNA Editing ADAR1 Deaminase Activation Responsive (READAR) platforms for dynamic detection of clonal myeloproliferative neoplasm stem cell fitness

Abstract Introduction Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell (HSC) derived disorders that can progress to acute myeloid leukemia (AML) at variable rates depending on macroenvironmental stressors and microenvironmental inflammatory cytokines. The total symptom score (TSS) and variant allele frequency (VAF) of mutations have proven valuable predictors of therapeutic response. Recently, we discovered inflammatory-cytokine-responsive ADAR1 RNA editing enzyme overexpression during MPN progression. However, dynamic prediction of clonal MPN stem cell fitness and progression to AML remains challenging. Methods We performed longitudinal 150-gene next-generation sequencing (NGS) analyses for 129 MPN patients. We developed single-cell RNA Editing ADAR1 Deaminase Activation Responsive (READAR) platforms to quantify ADAR1 activity with a novel ADAR1 nanoluc-GFP reporter assay, whole transcriptome RNA editome analyses, and MPN stem cell replating assays. To identify novel RNA editing sites, we performed whole genome sequencing on CD34+ cells from 43 MPN patients and whole transcriptome sequencing on FACS-purified HSC and progenitor cells from 32 MPN patients and 24 non-MPN controls. Results Sequential NGS analysis was performed with a median follow-up of 958 days (range 0-4214; interquartile range (IQR) 314-1350). On average, 6 NGS analyses (range 1-19; IQR 3-9) were performed for each patient. In our cohort, 58.9% of patients were JAK2 V617F+, while mutations in CALR and ASXL1 were observed in 11.6% and 14.0% of cases, respectively. In total, 44.2% (N=57) of patients in our cohort received Inrebic, with 56% reaching the maximum dose of 400mg. Notably, most patients on Inrebic were JAK2 V617F+ (N=38, 67.7%). In JAK2 V617F+ patients on Inrebic, 50% (n=19) experienced a reduction in the JAK2 V617F VAF from their peak value with a median drop of 16% (range 4-57). Our analyses using READAR platforms revealed increased RNA editing levels in JAK2 V617F+ patients from whole transcriptome sequencing analyses compared with JAK2 wild-type patients. Transduction of our ADAR1 nanoluc-GFP reporter into CD34+ cells from MPN patients (N=7), enabled us to quantify ADAR1 activity in an ex vivo setting. Moreover, CD34+ cells from MPN patient samples (n=7) treated in stromal co-cultures with ADAR1 inhibitor, Rebecsinib, demonstrated inhibition of self-renewal in replating assays. A significant reduction in ADAR1-GFP reporter activity was observed in MPN CD34+ cells following Rebecsinib treatment of stromal co-cultures. Also, humanized ADAR1-GFP-luciferase reporter AML mouse models showed a significant reduction in ADAR1 activity and leukemia stem cell self-renewal following Rebecsinib treatment. Conclusion These READAR platform results suggest that ADAR1 activity can be utilized to predict clonal MPN stem cell fitness and progression. Citation Format: Inge van der Werf, Larisa Balaian, Jessica Pham, Wenxue Ma, Athena Mohebbi, Emma Klacking, Antonio Ruiz, Karla Mack, John Mascarenhas, Thomas Whisenant, Ludmil Alexandrov, Sheldon Morris, Catriona Jamieson. RNA Editing ADAR1 Deaminase Activation Responsive (READAR) platforms for dynamic detection of clonal myeloproliferative neoplasm stem cell fitness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 263.

TNF-α is a predictive marker in distinguishing myeloproliferative neoplasm and idiopathic erythrocytosis/thrombocytosis: development and validation of a non-invasive diagnostic model.

Philadelphia-chromosome negative myeloproliferative neoplasms (MPN) exhibit phenotypic similarities with JAK/STAT-unmutated idiopathic erythrocytosis and thrombocytosis (IE/IT). We aimed to develop a clinical diagnostic model to discern MPN and IE/IT. A retrospective study was performed on 77 MPN patients and 32 IE/IT patients in our center from January 2018 to December 2023. We investigated the role of hemogram, cytokine and spleen size in differentiating MPN and IE/IT among newly onset erythrocytosis and thrombocytosis patients. Independent influencing factors were integrated into a nomogram for individualized risk prediction. The calibration and discrimination ability of the model were evaluated by concordance index (C-index), calibration curve. MPN had significantly higher TNF-α level than IE/IT, and the TNF-α level is correlated with MF-grade. Multivariable analyses revealed that TNF-α, PLT count, age, size of spleen were independent diagnostic factors in differentiating MPN and IE/IT. Nomograms integrated the above 4 factors for differentiating MPN and IE/IT was internally validated and had good performance, the C-index of the model is 0.979. The elevation of serum TNF-α in MPN patients is of diagnostic significance and is correlated with the severity of myelofibrosis. The nomogram incorporating TNF-α with age, PLT count and spleen size presents a noteworthy tool in the preliminary discrimination of MPN patients and those with idiopathic erythrocytosis or thrombocytosis. This highlights the potential of cytokines as biomarkers in hematologic disorders.

Abstract 1485: Hallmarks of APOBEC3 mutagenesis in normal, pre-leukemic, and myeloproliferative neoplasm cell populations

Abstract Changes in gene expression and subsequent editing patterns of APOBEC3 (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like) cytosine deaminases have been shown to be present in solid tumor cancer evolution, however, the context specificity and mechanisms by which APOBEC3 enzymes promote cancer initiation and progression require further elucidation, especially in the hematopoietic niche. Building on advanced sequencing data of healthy, pre-leukemic, and myeloproliferative neoplasm patient samples, we seek to uncover normal and malignant patterns of APOBEC3C overexpression in hematopoietic cells. Overexpression of lentiviral APOBEC3C and an editase-mutated APOBEC3C in normal cord blood, healthy bone marrow, and MPN patient hematopoietic stem/progenitor cells (HSPCs) allows us to study the effects of deaminase dysregulation in hematopoietic cells. In addition to APOBEC3, we are exploring the upregulation of adenosine deaminase acting on RNA1 (ADAR1), as we have previously shown that these two innate immune deaminases are synchronously upregulated in the high-risk myelofibrosis (MF) stem cell population compared to normal aged bone marrow. These overexpression studies show novel differential gene expression changes, RNA hyper-editing sites, and DNA mutation signatures induced by APOBEC3 mutagenesis, which can be cross-referenced to gene expression and mutation signatures seen in hematopoietic malignancies and solid tumor cancers. In addition to mutation patterns, the regulation of LINE-1 elements has been shown to be another important function of APOBEC3 enzymes. In these studies, we examine the effects of APOBEC3 overexpression on repetitive element expression in hematopoietic cell populations and have found that there are strong cell type and context patterns across the APOBEC3 family and between cell types within the hematopoietic system. We will use this comprehensive study of APOBEC3 deregulation to uncover predictive biomarkers of malignant transformation. Citation Format: Jane Marie Isquith, Thomas Whisenant, Jessica Pham, Ludmil Alexandrov, Catriona Jamieson. Hallmarks of APOBEC3 mutagenesis in normal, pre-leukemic, and myeloproliferative neoplasm cell populations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1485.

Does Double Mean Trouble? Coexistence of Myeloproliferative and Lymphoproliferative Neoplasms.

Background: The occurrence of myeloproliferative neoplasms (MPNs) that evolve into each other is well-described, as is this occurrence of lymphoproliferative neoplasms (LPNs). However, less is known about rare MPN/LPN coexistence, and the aim of our study was to analyze charachteristics of these patients after long term follow-up. Methods: Fourteen patients with MPN/LPN coexistence were diagnosed and treated according to guidelines at a single university center across two decades. Results: The overall median age was 53 years (22-69). MPNs patients with subsequent LPNs had a shorter period of second malignancy development and a more aggressive course of LPN, which can cause fatal outcomes. Polycythemia vera and chronic lymphocytic leukemia were most commonly associated (36%). The JAK2V617F mutation had 2/3 and cytogenetic abnormalities occurred in 1/3 of patients. MPN/LPN coexistence cases had significantly higher thrombotic potential (42.8%) and a higher third malignancy accruement frequency (21.4%) versus those without such malignancies. Conclusions: Considering the younger ages at MPN diagnosis, it is recommended to check regularly for blood lymphocytosis or lymphadenopathy occurrences and organomegaly progression faster than expected for MPN, with the aim of timely LPN diagnoses. The presence of molecular-cytogenetic abnormalities in a majority of patients indicate possible genetic instability and increased risk of development of multiple neoplasms, thus elevating thrombotic risk.

The Role of DNA Repair (XPC, XPD, XPF, and XPG) Gene Polymorphisms in the Development of Myeloproliferative Neoplasms.

Background and Objectives: Several polymorphisms have been described in various DNA repair genes. Nucleotide excision DNA repair (NER) detects defects of DNA molecules and corrects them to restore genome integrity. We hypothesized that the XPC, XPD, XPF, and XPG gene polymorphisms influence the appearance of myeloproliferative neoplasms (MPNs). Materials and Methods: We investigated the XPC 1496C>T (rs2228000, XPC Ala499Val), XPC 2920A>C (rs228001, XPC Lys939Gln), XPD 2251A>C (rs13181, XPD Lys751Gln), XPF-673C>T (rs3136038), XPF 11985A>G (rs254942), and XPG 3507G>C (rs17655, XPG Asp1104His) polymorphisms by polymerase chain reaction-restriction fragment length polymorphism analysis in 393 MPN patients [153 with polycythemia vera (PV), 201 with essential thrombocythemia (ET), and 39 with primary myelofibrosis (PMF)] and 323 healthy controls. Results: Overall, we found that variant genotypes of XPD 2251A>C were associated with an increased risk of MPN (OR = 1.54, 95% CI = 1.15-2.08, p = 0.004), while XPF-673C>T and XPF 11985A>G were associated with a decreased risk of developing MPN (OR = 0.56, 95% CI = 0.42-0.76, p < 0.001; and OR = 0.26, 95% CI = 0.19-0.37, p < 0.001, respectively). Conclusions: In light of our findings, XPD 2251A>C polymorphism was associated with the risk of developing MPN and XPF-673C>T and XPF 11985A>G single nucleotide polymorphisms (SNPs) may have a protective role for MPN, while XPC 1496C>T, XPC 2920A>C, and XPG 3507G>C polymorphisms do not represent risk factors in MPN development.

A Review About the Assessment of the Bleeding and Thrombosis Risk for Patients With Myeloproliferative Neoplasms Scheduled for Surgery.

Myeloproliferative neoplasms (MPNs) present a unique challenge in surgical management due to their inherent predisposition to both bleeding and thrombosis. MPNs are a heterogenous group of acquired clonal conditions. The three classic MPNs are essential thrombocythemia (ET), myelofibrosis (PMF), and polycythemia vera (PV). All subtypes of MPN are associated with both thrombotic and bleeding complications. There are four risk categories for thrombosis in MPN patients: age, thrombosis history, and JAK-2 mutation. They are further classified as very low, low, intermediate, and high risk. The genetic landscape of MPN is fascinating and complex like all myeloid disorders. Bleeding risk can be assessed through leukocytosis, thrombocytosis, acquired von Willebrand syndrome (AVWS), and a previous history of bleeding in a patient.Risk assessment and perioperative management are important aspects of improving the quality of life and preventing complications in surgeries. Preoperative management includes a risk assessment of venous thromboembolism, use of appropriate pharmacological treatment, platelet count control, and correction and cardiovascular risk factors. This review summarizes the assessment of bleeding and thrombosis risk for patients with MPNs scheduled for surgery. Furthermore, this review discusses various tools that can be used to identify MPN patients at risk of thrombosis prior to surgery.

Risk of thrombosis, hemorrhage and leukemic transformation in patients with myeloproliferative neoplasms: A nationwide longitudinal cohort study

IntroductionThere are few large-scale, population-based studies detailing the risks of thrombosis, hemorrhage, leukemic transformation in patients with myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). MethodsWe performed a nationwide longitudinal cohort study using the Korean National Health Insurance System (NHIS) database. MPN patients (n = 11,991) and their 1:4 age- and sex-matched controls (n = 47,964) were enrolled. The risk of thrombosis, hemorrhage, leukemic transformation was estimated using a Cox proportional hazards regression, and stratified analyses were performed for related factors. ResultsDuring a median of 7.8 years of follow-up, 30.1 % of MPN patients (3614/11,991) and 19.0 % of the matched controls (9141/47,964) developed arterial thrombosis, 11.6 % of MPN patients (1397/11,991) and 6.4 % of the matched controls (3099/47,964) developed venous thrombosis and 18.7 % of MPN patients (2251/11,991) and 12.1 % of the matched controls (5836/47,964) developed hemorrhage. 4.9 % of MPN patients (597/11,991) and 0.1 % of matched controls (50/47,964) developed leukemia. The overall risk of developing thrombosis, hemorrhage, leukemic transformation was higher in MPN patients (adjusted hazard ratio [aHR] 1.695, 95 % confidence interval [CI]: 1.629–1.765 for arterial thrombosis, aHR 1.963, 95 % CI: 1.838–2.096 for venous thrombosis, and aHR 1.714, 95 % CI: 1.630–1.802 for hemorrhage) than in the controls. Patients with MPNs had a 10-year cumulative incidence of leukemic transformation of 6.2 %. ConclusionThe patients with MPNs have a higher risk of thrombosis, hemorrhage, and leukemic transformation than matched controls. Strategies are warranted to reduce the risk of thrombosis, hemorrhage, and leukemic transformation in MPN patients.

SHP2 inhibition displays efficacy as a monotherapy and in combination with JAK2 inhibition in preclinical models of myeloproliferative neoplasms.

Myeloproliferative neoplasms (MPNs), including polycythemia vera, essential thrombocytosis, and primary myelofibrosis, are clonal hematopoietic neoplasms driven by mutationally activated signaling by the JAK2 tyrosine kinase. Although JAK2 inhibitors can improve MPN patients' quality of life, they do not induce complete remission as disease-driving cells persistently survive therapy. ERK activation has been highlighted as contributing to JAK2 inhibitor persistent cell survival. As ERK is a component of signaling by activated RAS proteins and by JAK2 activation, we sought to inhibit RAS activation to enhance responses to JAK2 inhibition in preclinical MPN models. We found the SHP2 inhibitor RMC-4550 significantly enhanced growth inhibition of MPN cell lines in combination with the JAK2 inhibitor ruxolitinib, effectively preventing ruxolitinib persistent growth, and the growth and viability of established ruxolitinib persistent cells remained sensitive to SHP2 inhibition. Both SHP2 and JAK2 inhibition diminished cellular RAS-GTP levels, and their concomitant inhibition enhanced ERK inactivation and increased apoptosis. Inhibition of SHP2 inhibited the neoplastic growth of MPN patient hematopoietic progenitor cells and exhibited synergy with ruxolitinib. RMC-4550 antagonized MPN phenotypes and increased survival of an MPN mouse model driven by MPL-W515L. The combination of RMC-4550 and ruxolitinib, which was safe and tolerated in healthy mice, further inhibited disease compared to ruxolitinib monotherapy, including extending survival. Given SHP2 inhibitors are undergoing clinical evaluation in patients with solid tumors, our preclinical findings suggest that SHP2 is a candidate therapeutic target with potential for rapid translation to clinical assessment to improve current targeted therapies for MPN patients.

Clinical Features and Long-Term Outcomes of a Pan-Canadian Cohort of Adolescents and Young Adults with Myeloproliferative Neoplasms: A Canadian MPN Group Study.

Myeloproliferative neoplasms (MPNs) are a group of chronic hematologic malignancies that lead to morbidity and early mortality due to thrombotic complications and progression to acute leukemia. Clinical and mutational risk factors have been demonstrated to predict outcomes in patients with MPNs and are used commonly to guide therapeutic decisions, including allogenic stem cell transplant, in myelofibrosis. Adolescents and young adults (AYA, age ≤45 years) comprise less than 10% of all MPN patients and have unique clinical and therapeutic considerations. The prevalence and clinical impact of somatic mutations implicated in myeloid disease has not been extensively examined in this population. We conducted a retrospective review of patients evaluated at eight Canadian centers for MPN patients diagnosed at ≤45 years of age. In total, 609 patients were included in the study, with median overall survival of 36.8 years. Diagnosis of prefibrotic or overt PMF is associated with the lowest OS and highest risk of AP/BP transformation. Thrombotic complications (24%), including splanchnic circulation thrombosis (9%), were frequent in the cohort. Mutations in addition to those in JAK2/MPL/CALR are uncommon in the initial disease phase in our AYA population (12%); but our data indicate they may be predictive of transformation to post-ET/PV myelofibrosis.

Analysis of CHIP-Related Mutation and Risk of Cardio-Cerebrovasculars Events in Patients with Myeloproliferative Neoplasms

To analyze the mutant spectrum of clonal hematopoiesis of indeterminate potential (CHIP) related mutations and clinical characteristics and to explore the correlation and the possible mechanism between CHIP-related mutations and cardio-cerebrovasculars events (CCEs) in patients with myeloproliferative neoplasms (MPNs). The clinical data and next-generation sequencing results of 73 MPN patients in Beijing Anzhen Hospital from August 2019 to July 2022 were retrospectively analyzed. Statistical analyses were conducted by multivariate logistic regression for the effects of CHIP-related mutations and inflammatory cytokines on CCEs for MPNs patients. Fifty-five cases of MPN (75.3%) showed positive in CHIP-related genes. There was no significant difference in variant allele frequency of CHIP-related gene between essential thrombocythemia (ET) and polycythemia vera (PV). CHIP-related gene mutations were mainly single gene mutations, with mutation rate from high to low as JAK2V617F (63.0%, 46/73), ASXL1 (16.4%, 12/73), TET2 (11.0%, 8/73), DNMT3A (9.6%, 7/73), SRSF2 (6.9%, 5/73), SF3B1 (4.1%, 3/73), TP53(1.4%, 1/73) and PPM1D (1.4%, 1/73). The mutation rate of CHIP-related genes in MPN patients >60 years old was significantly higher than that in the patients ≤60 years old ［91.7%(33/36) vs 59.5%(22/37)］. CCEs occurred in 27 MPNs patients (37.0%, MPNs/CCEs), and 5 had recurrent CCEs, all of which were arterial events. Age (62.8±12.8 years vs 53.9±15.8 years, P =0.015), IL-1β level (17.7±26.0 vs 4.3±8.6, P =0.012), IL-8 level (360.7±598.6 vs 108.3±317.0, P =0.045), the proportion of the patients with thrombosis history (29.6% vs 2.2%, P =0.020), and the detection rate of CHIP-related mutations (88.9% vs 67.4%, P =0.040) in the group with CCEs were higher than those in the group without CCEs. Multivariate Logistic regression analysis showed that age（OR =0.917， 95%CI ：0.843-0.999, P =0.047）, thrombosis history (OR =34.148， 95%CI ：2.392-487.535, P =0.009), any CHIP-related mutations(OR =16.065， 95%CI ：1.217-212.024， P =0.035), and elevated level of IL-1β (OR =0.929， 95%CI ：0.870-0.992， P =0.027) were independent risk factors for MPNs/CCEs. CHIP-related gene mutations were not associated with CCEs in MPN patients, but DNMT3A (OR =88.717， 95%CI ：2.690-292.482， P =0.012) and ASXL1 (OR =7.941， 95%CI ：1.045-60.353， P =0.045) were independent risk factors for CCEs in PV. There is a higher mutation rate of CHIP-related genes in MPN patients, especially those over 60 years old. Older age, thrombosis history, CHIP-related mutations and IL-1β elevated levels are independent risk factors for CCEs in MPN. DNMT3A and ASXL1 mutations are independent risk factors for CCEs in PV patients. CHIP-related gene mutations and inflammatory cytokine IL-1 β elevated levels may be the novel risk factors for CCEs in MPN.

JAK2V617F drives gut microbiota differences in patients with myeloproliferative neoplasms.

Essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (MF) are myeloproliferative neoplasms (MPN). Inflammation is involved in the initiation, progression, and symptomology of the diseases. The gut microbiota impacts the immune system, infection control, and steady-state hematopoiesis. We analyzed the gut microbiota of 227 MPN patients and healthy controls (HCs) using next-generation sequencing. We expanded our previous results in PV and ET patients with additional PV, pre-MF, and MF patients which allowed us to compare MPN patients collectively, MPN sub-diagnoses, and MPN mutations (separately and combined) vs. HCs (N = 42) and compare within MPN sub-diagnoses and MPN mutation. MPN patients had a higher observed richness (median, 245 [range, 49-659]) compared with HCs (191.5 [range, 111-300; p = .003]) and a lower relative abundance of taxa within the Firmicutes phylum; for example, Faecalibacterium (6% vs. 14%, p < .001). The microbiota of CALR-positive patients (N = 30) resembled that of HCs more than that of patients with JAK2V617F (N = 177). In JAK2V617F-positive patients, only minor differences in the gut microbiota were observed between MPN sub-diagnoses, illustrating the importance of this mutation. The gut microbiota in MPN patients differs from HCs and is driven by JAK2V617F, whereas the gut microbiota in CALR patients resembles HCs more.

Insights into the role of JAK2-I724T variant in myeloproliferative neoplasms from a unique cohort of New Zealand patients

ABSTRACT Objectives: This study aimed to compile bioinformatic and experimental information for JAK2 missense variants previously reported in myeloproliferative neoplasms (MPN) and determine if germline JAK2-I724T, recently found to be common in New Zealand Polynesians, associates with MPN. Methods: For all JAK2 variants found in the literature, gnomAD_exome allele frequencies were extracted and REVEL scores were calculated using the dbNSFP database. We investigated the prevalence of JAK2-I724T in a cohort of 111 New Zealand MPN patients using a TaqMan assay, examined its allelic co-occurrence with JAK2-V617F using Oxford Nanopore sequencing, and modelled the impact of I724T on JAK2 using I-Mutant and ChimeraX software. Results: Several non-V617F JAK2 variants previously reported in MPN had REVEL scores greater than 0.5, suggesting pathogenicity. JAK2-I724T (REVEL score 0.753) was more common in New Zealand Polynesian MPN patients (n = 2/27; 7.4%) than in other New Zealand patients (n = 0/84; 0%) but less common than expected for healthy Polynesians (n = 56/377; 14.9%). Patients carrying I724T (n = 2), one with polycythaemia vera and one with essential thrombocythaemia, had high-risk MPN. Both patients with JAK2-I724T were also positive for JAK2-V617F, found on the same allele as I724T, as well as separately. In silico modelling did not identify noticeable structural changes that would give JAK2-I724T a gain-of-function. Conclusion: Several non-canonical JAK2 variants with high REVEL scores have been reported in MPN, highlighting the need to further understand their relationship with disease. The JAK2-I724T variant does not drive MPN, but additional investigations are required to exclude any potential modulatory effect on the MPN phenotype.

Genomic and functional impact of Trp53 inactivation in JAK2V617F myeloproliferative neoplasms

Classical myeloproliferative neoplasms (MPNs) are characterized by the proliferation of myeloid cells and the risk of transformation into myelofibrosis or acute myeloid leukemia (AML) and TP53 mutations in MPN patients are linked to AML. However, JAK2V617F has been reported to impact the TP53 response to DNA damage, suggesting potential overlapping role of TP53 inactivation in MPN. We established a mouse model showing that JAK2V617F/Vav-Cre/Trp53−/− mice displayed a similar phenotype to JAK2V617F/Vav-Cre mice, but their proliferation was outcompeted in competitive grafts. RNA-Seq revealed that half of the genes affected by JAK2V617F were affected by p53-inactivation, including the interferon pathway. To validate this finding, mice were repopulated with a mixture of wild-type and JAK2V617F (or JAK2V617F/Vav-Cre/Trp53−/−) cells and treated with pegylated interferonα. JAK2V617F-reconstituted mice entered complete hematological remission, while JAK2V617F/Vav-Cre /Trp53−/−-reconstituted mice did not, confirming that p53 loss induced interferon-α resistance. KEGG and Gene Ontology analyses of common deregulated genes showed that these genes were mainly implicated in cytokine response, proliferation, and leukemia evolution, illustrating that in this mouse model, the development of MPN is not affected by TP53 inactivation. Taken together, our results show that many genetic modifications induced by JAK2V617F are influenced by TP53, the MPN phenotype may not be. Trp53 loss alone is insufficient to induce rapid leukemic transformation in steady-state hematopoiesis in JAK2V617F MPN, and Trp53 loss may contribute to interferon resistance in MPN.