JAK2V617F Allele Burden Research Articles

Study of JAK2 V617F allele Burden By Droplet Digital PCR in BCR-ABL1 Negative Myeloproliferative Neoplasms and Its Implications on Disease Phenotype

JAK2V617F mutation is the most common mutation seen among the BCR-ABL1 negative myeloproliferative neoplasms, the incidence of which is 90-95% in PV, 50-70% in ET and 40-50% in PMF. The discovery of the association of JAK2 V617F mutation with all the above mentioned myeloproliferative neoplasms and MPN-U boggled the minds of many scientists on how a single gene mutation can cause different disorders, and it was later reported that the allele burden determines the clinical phenotype of the disease. With the advent of droplet digital polymerase chain reaction(ddPCR), even a small quantity of JAK2 V617F allele burden could be detected and measured, facilitating an earlier definitive diagnosis and hence early treatment. In addition, with the rise in use of JAK2 inhibitors such as Ruxolitinib for treating high risk patients, the quantification of allele burden could probably play a role in defining treatment guidelines for usage of these drugs. Method: After examination of bone marrow aspirate smears and biopsies in clinically suspected cases of MPN, molecular testing and allele burden quantification of JAK2 V617F mutation was done using ddPCR. The objectives of our study was to correlate the allele burden with the clinical phenotype, it's implication on the symptom burden and hematological parameters and it's correlation with the prognosis of patients. The symptom burden was measured using MPNTEN Score, whereas the prognosis for PV and ET was done based on Prognostic risk score for thrombosis. Prognostication of PMF was done using IPSS and DIPSS. Results: In our study, among 50 patients, 50% (n=25) were diagnosed as PV, 30% (n=15) were diagnosed as Primary myelofibrosis, 16 % as ET (n=8) and 4% (n=2) as MPN-U. The mean allele burden of PV was highest (64.5%), closely followed by PMF at 61.65% and lowest in ET (31.17%). The allele burden showed significant (p<0.05) positive correlation with the symptom burden in patients. It was also found that a significant association between presence of para trabecular megakaryocyte localization and allele burden exists (p value of 0.02). It was observed that a significant correlation exists between previous history of thrombosis with increased allele burden at presentation (p<0.05). However, the allele burden quantification at presentation and prognostic scores of PV, ET and PMF did not show significant correlation. Conclusion: To conclude, our study reports that the allele burden varies according to the clinical phenotype, has a bearing on the symptom burden of patients, has morphological implications and has a strong correlation with prior thrombotic episodes. Follow up of these patients based on remission criteria for PV, ET and PMF are being done and will be presented.

Efficacy and Safety of Long-Term Ropeginterferon Alfa-2b Treatment in Patients with Low-Risk and High-Risk Polycythemia Vera (PV)

Introduction: Patients with "low-risk” (LR) PV are managed conservatively despite higher risk of vascular events and impaired quality of life compared to a population without PV. Acknowledging new evidence (LOW-PV study, Barbui et al 2021), recent treatment guidelines (European LeukemiaNet [ELN] 2021) recommend ropeginterferon alfa-2b (BESREMi®) as a cytoreductive treatment in LR PV patients meeting specific criteria as well as in high-risk (HR) PV patients. Final data from the phase 3 PROUD-PV and CONTINUATION-PV trials (NCT01949805; NCT02218047) demonstrated the long-term efficacy and safety of ropeginterferon alfa-2b compared with hydroxyurea/best available treatment (HU/BAT); here we report results in the ropeginterferon alfa-2b arm by risk stratum. Methods: PV patients were randomized 1:1 and received ropeginterferon alfa-2b or HU/BAT for ≥6 years. In the ropeginterferon alfa-2b arm, subgroup analyses were performed post-hoc by risk stratum (LR: age ≤60 years and no history of thrombosis; all others HR). Complete hematologic response (CHemR) and molecular response defined by modified ELN criteria were assessed in the full analysis set for CONTINUATION-PV (N=95); safety analyses included all data regardless of roll-over (N=127). Results: CONTINUATION-PV enrolled 46 LR and 49 HR patients in the ropeginterferon alfa-2b arm. At baseline, mean age was 50.7 vs 63.7 years respectively, and median duration since PV diagnosis was 1.9 months vs 1.5 months. HR patients had higher platelet and leukocyte counts at baseline and more frequently presented with clinically significant splenomegaly or PV-related symptoms. Median JAK2V617F allele burden was similar for LR and HR patients (37.0% vs 39.4%), however LR patients were less likely to harbor additional non-driver mutations (11.4% vs 24.4%). The median 4-weekly ropeginterferon alfa-2b dose was comparable in LR and HR patients throughout the study (in the 6th year, 499 µg and 489µg respectively) as was the use of an extended 3-4 weekly dose regimen (6th year: 59.5% vs 65.4%). LR patients achieved a significantly higher CHemR rate than HR patients during long-term treatment (Month 72: 73.2% vs 38.3% in LR and HR respectively [RR: 2.41; 95% CI: 1.50 to 3.90; p=0.0003]). Higher CHemR among LR patients was confirmed in a sensitivity analysis including discontinued patients (last observation carried forward [LOCF]; 80.4% in LR vs 65.3% in HR patients at Month 72) indicating that in the HR group, more patients discontinued despite CHemR. In general, discontinued patients were older than those who completed the study (mean age 62.8 years vs 55.2 years) but did not have a longer duration of PV or markedly greater symptom burden at baseline. Importantly, regardless of risk stratum, most patients receiving ropeginterferon alfa-2b did not require any phlebotomy for the entire 6th year (85.7% of LR patients and 75.0% of HR patients entering the 6th year [p=0.3]). LR patients had a higher molecular response rate than HR patients (LOCF at Month 72: 84.4% vs 49.0% respectively, RR: 2.15 [95% CI: 1.37 to 3.37]; p=0.0009) and achieved molecular response more rapidly (median time to first response: 12 months [95% CI: 12 to 18] vs 18 months [95% CI: 12 to 24]; Log-rank test p=0.03). The median JAK2V617F allele burden was 5.6% for LR and 17.9% for HR patients at Month 72 (p<0.0001). During the entire PROUD-PV/CONTINUATION-PV studies (≥6 years exposure), adverse drug reactions (ADRs) to ropeginterferon alfa-2b led to withdrawal of treatment in 1 (1.8%) LR patient (due to sarcoidosis), and in 13 (18.3%) HR patients (due to thrombocytopenia [n=1], elevated transaminases [n=1], psychiatric disorders [n=2], autoimmune disorders [n=6], hypothyroidism [n=2] and dyspnea/pneumonitis [n=1]). LR patients were also less likely than HR patients to experience ADRS of grade ≥3 severity (5.4% vs 23.9%). Conclusion: These results demonstrate the benefit of ropeginterferon alfa-2b therapy in both HR and LR patient populations. LR patients may have a greater potential benefit: higher hematologic and molecular response rates can be safely achieved, and the patients are more likely to remain on long-term treatment. These data provide further evidence for an early treatment start as recently outlined by the updated ELN guidelines.

Prevalence of the JAK2V617F Mutation in Patients with Ischemic Stroke

Introduction: Patients with the Philadelphia negative myeloproliferative neoplasms (MPN) have an increased risk of thromboembolic events, ischemic cerebrovascular events in particular. The somatic mutation JAK2V617F is associated with MPN with a prevalence of 96% in polycythemia vera (PV), 55% in essential thrombocythemia (ET), and 65% in primary myelofibrosis (PMF). The JAK2V617F mutation is found to be an independent risk factor for thrombosis in patients with MPN. However, whether the JAK2V617F mutation is a risk factor for arterial thrombosis in the absence of an MPN diagnosis is still uncertain. The sensitivity of the assay used for detection is crucial when assessing the presence of the JAK2V617F mutation. A higher sensitivity enables detection of lower allele burdens. This is illustrated by the varying prevalences (0.1-3.1%) in background population studies. In the Danish population study GESUS of approximately 20.000 individuals, the JAK2V617F mutation was detected by droplet digital PCR (ddPCR) with an assay sensitivity of 0.009%. The GESUS study found a JAK2V617F prevalence of 3.1%. Similarly, prevalence studies of JAK2V617F mutation in stroke have varying detection limits from 0.01-5% mutant alleles. The vast majority of these studies are retrospective studies in younger subpopulations of stroke patients. We aimed to investigate the prevalence of the JAK2V617F mutation in a prospective design of consecutively enrolled unselected patients with ischemic stroke or transient ischemic attack by the highly sensitive ddPCR. Method: We recruited 90 consecutive patients with ischemic stroke or transient ischemic attack during admission at the Department of Neurology, Zealand University Hospital, Denmark. A blood sample was taken within 7 days of the onset of symptoms and screened for the JAK2V617F mutation by ddPCR. Patients unable to give informed consent were excluded from the study. Results: Out of 90 patients (mean age 71, range 46-92; female 37%) with ischemic stroke or transient ischemic attack, the JAK2V617F mutation was found in 11 patients (12.2%). Allele burdens ranged from 0.0021 to 24. All 11 patients suffered an ischemic stroke. Six out of 11 patients with the JAK2V617F mutation had elevated blood cell levels i.e. erythrocytosis, thrombocytosis, and/or leukocytosis at the time of recruitment. Only three patients had continuously elevated blood cell levels after 1 month. Patient no. 6 with a JAK2V617F mutation allele burden of 34% had blood cell levels meeting the diagnostic criteria for MPN and was diagnosed with ET. Patient no. 2 had a JAK2V617F allele burden of 14% and increased levels of hemoglobin and platelet count, which both normalized spontaneously after 1 month. The patient was referred for a hematological workup and was found to have mild splenomegaly and a bone marrow biopsy showing myeloproliferative features. In light of the normal blood cell parameters, patient no. 2 was diagnosed with MPN-U. The patients with a JAK2V617F mutation are presented in table 1. Additional data will be presented at ASH. Conclusion and implications: The present study reveals a JAK2V617F mutation prevalence (12.2%) in a stroke population that is substantially higher compared to the background population (GESUS) in the same region of Denmark, using the same assay. The GESUS study showed a JAK2V617F mutationprevalence of 3.1% and for individuals above age 60 a prevalence of 4.1%. Given the fact that the JAK2V617F mutation is present in patients with and without cytosis, our results highly suggest that the JAK2V617F mutation per se is a thrombogenic factor in ischemic stroke. This calls for an exploration of the pathophysiological mechanisms and potential treatments to prevent future thrombotic events in individuals with and without cytosis. Table legend: Clinical and paraclinical characteristics of ischemic stroke patients with the JAK2V617F mutation. IS, ischemic stroke; TIA, transient ischemic attack; HTN, hypertension; HLP, hyperlipidemia; AF, atrial fibrillation; IHD, ischemic heart disease; DM2, diabetes mellitus type 2; Hb, hemoglobin; PLT, platelet count; WBC, white blood cells. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Ropeginterferon-alfa2b resolves angina pectoris and reduces JAK2V617F in a patient with clonal hematopoiesis of indeterminate potential: A case report

The JAK2V617F mutation is an acquired somatic mutation, which is prevalent in patients with the Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs). In these diseases the mutation gives rise to constitutive JAK-STAT signaling with increased blood cell counts and in vivo activation of neutrophils and platelets as well, which altogether contribute to a chronic inflammatory and thrombogenic state with a 12-fold increased risk of coronary disease. Treatment with recombinant interferon-alpha2 (rIFN) reduces the JAK2V617F allelic burden in a large number of MPN-patients. Long-term treatment with rIFN associates with low-burden JAK2V617F in a subset of patients and a decreased thrombosis risk as well. In the general population the JAK2V617F mutation has been shown to associate with ischemic heart disease and thrombosis. Based upon the above observations we herein report the first patient with CHIP-JAK2V617F, in whom treatment with rIFN resolved severe angina pectoris. During a short period off rIFN the symptoms reappeared to resolve in concert with reduction of JAK2V617F allele burden, when rIFN was reinstituted. The JAK2V617F mutation may be a novel therapeutic target to prohibit the development of cardiovascular diseases using rIFN either as monotherapy or in combination with potent anti-inflammatory agents.

High JAK2V617F allele burden is associated with an increased burden of coronary artery calcification in MPNs

Abstract Background Patients with the haematological cancers Philadelphia-negative Myeloproliferative Neoplasms (MPNs), have an increased risk of coronary artery and aortic valve calcification, and an increased risk of myocardial infarctions. The most common acquired mutation in MPNs, the JAK2V617F mutation, has been linked to increased risk of thrombosis. Aims To exam the association between the JAK2V617F mutation, its allele burden, and coronary artery and aortic valve calcification. Methods One hundred and sixty one patients with MPN disease from one specialized haematological outpatient clinic where included. Information on demographics, smoking, alcohol habits and co-morbidities were registered. Blood samples were drawn for determination of the JAK2V617 mutation and allele burden. Patients were examined by cardiac computer tomography in order to determine their coronary artery calcium score (CACS) and aortic valve calcification (AVC) score. The association between the JAK2V617F mutation, its allele burden and coronary artery and aortic calcification was investigated with univariate and multivariate logistic regression analysis, adjusting for age, sex, ischemic heart disease (IHD), stroke, smoking, obesity, hypertension, hypercholesterolemia, diabetes mellitus, and family history of IHD or stroke in the multivariate analysis. Results Of the 161 patients (52% male, mean age 65.5±10.5 years), 137 (85%) were JAK2V617F positives, and the JAK2V617F allele burden was quantified in 120. The median JAK2V617F allele burden was 12% (IQR range 6–33%). There were 42 (26%) patients with a CACS &amp;gt;400, and 93 (58%) patients AVC. Among the JAK2V617F positive patients, 38 (24%) had a CACS &amp;gt;400 and 81 (59%) had AVC. In the 32 patients with a JAK2V617F allele burden&amp;gt;33%, 19 (59%) had a CACS &amp;gt;400 and 26 (81%) had AVC. In the univariate logistic regression analysis the presence of JAK2V617F mutation was not associated with a CACS &amp;gt;400 (Odds Ratio (OR) 1.92, 95% confidence interval (CI) 0.62–5.98, p=0.26). Similar result was found for the analysis on AVC (OR 1.45, 95% CI 0.61–3.45, p=0.41). In contrast, a JAK2V617F allele burden &amp;gt;33% was significantly associated with a CACS &amp;gt;400 (OR 5.31, 95% CI 2.23–12.66, p=0.0002), and similarly with AVC (OR 4.14, 95% CI 1.55–11.05, p=0.0045). In the multivariate adjusted analysis, a JAK2V617F allele burden &amp;gt;33% was significantly associated with a CACS &amp;gt;400 (OR 2.08, 95% CI 0.43–10.10, p=0.36), but not with AVC (OR 0.90, 95% CI 0.27–3.03, p=0.86). In the adjusted analysis the association between a JAK2V617F allele burden &amp;gt;33% and CACS &amp;gt;400 was significant (OR3.86, 95% CI 1.14–13.09, p=0.031), but the analysis on AVC was not (OR 1.59, 95% CI 0.42–6.04, p=0.50). Conclusion There is a significant association between a JAK2V617F allele burden &amp;gt;33% and the burden of coronary calcification in MPNs, measured as a CACS &amp;gt;400. The association remains significant after adjustment for cardiovascular risk factors. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Region Sjællands Sundhedsvidenskabelige ForskningsfondTømrermester Jørgen Holm og hustru Elisa F. Hansens Mindelegat

Simultaneous detection of JAK2 , CALR , and MPL mutations and quantitation of JAK2 V617F allele burden in myeloproliferative neoplasms using the quenching probe‐Tm method in i‐densy IS ‐5320

Accurate detection of myeloproliferative neoplasms (MPN)-associated gene mutations is necessary to correctly diagnose MPN. However, conventional gene testing has various limitations, including the requirement of skilled technicians, cumbersome experimental procedures, and turnaround time of several days. The gene analyzer i-densy IS-5320 allows gene testing using the quenching probe-Tm method. Specifically, pretreatment of samples including DNA extraction, amplification and detection of genes, and analysis of results are performed in a fully automatic manner after samples and test reagents are added into this system, which is compact and can be easily installed in a laboratory. The aim of this study is to investigate the sensitivity and specificity associated with the simultaneous detection of MPN-associated gene mutations. We conducted an analysis of MPN-associated genes using i-densy IS-5320. We analyzed 384 samples (171 JAK2 V617F mutations, 10 JAK2 exon12 mutations, 104 CALR mutations, and 26 MPL mutations) that had been examined using conventional approaches such as allele-specific polymerase chain reaction (PCR), droplet digital PCR, and the direct sequencing method. The detection accuracy of JAK2 V617F, JAK2 exon 12, CALR, and MPL was 100.0% (383/383), 99.7% (383/384), 100.0% (370/370), and 99.7% (377/378), respectively. There was a strong positive correlation between the JAK2 V617F allele burden measured using conventional methods and i-densy IS-5320 (r=.989). Overall, i-densy IS-5320 exhibited good accuracy in terms of analyzing MPN-associated genes; thus, it can serve as a replacement for conventional methods of MPN-associated gene testing.

Low-risk polycythemia vera treated with phlebotomies: clinical characteristics, hematologic control and complications in 453 patients from the Spanish Registry of Polycythemia Vera

Hematological control, incidence of complications, and need for cytoreduction were studied in 453 patients with low-risk polycythemia vera (PV) treated with phlebotomies alone. Median hematocrit value decreased from 54% at diagnosis to 45% at 12 months, and adequate hematocrit control over time (< 45%) was observed in 36%, 44%, and 32% of the patients at 6, 12, and 24 months, respectively. More than 5 phlebotomies per year in the maintenance phase were required in 19% of patients. Worsening thrombocytosis, age > 60 years, and microvascular symptoms constituted the main indications for starting cytoreduction. Median duration without initiating cytoreduction was significantly longer in patients younger than 50 years (< 0.0001). The incidence rate of thrombosis under phlebotomies alone was 0.8% per year and the estimated probability of thrombosis at 10 years was 8.5%. The probability of arterial thrombosis was significantly higher in patients with arterial hypertension whereas there was a trend to higher risk of venous thrombosis in cases with high JAK2V617F allele burden. Rates of major bleeding and second primary neoplasm were low. With a median follow-up of 9 years, survival probability at 10 years was 97%, whereas the probability of myelofibrosis at 10 and 20 years was 7% and 20%, respectively. Progression to acute myeloid leukemia was documented in 3 cases (1%). Current management of low-risk PV patients is associated with low rate of thrombosis and long survival. New treatment strategies are needed for improving hematological control and, in the long term, reducing progression to myelofibrosis.

A Phase Ib Dose-finding Study of Panobinostat and Ruxolitinib in Myelofibrosis.

A Phase Ib Dose-finding Study of Panobinostat and Ruxolitinib in Myelofibrosis.

CHST15 gene germline mutation is associated with the development of familial myeloproliferative neoplasms and higher transformation risk

Herein, we describe the clinical and hematological features of three genetically related families predisposed to myeloproliferative neoplasms (MPNs). Using whole-exome sequencing, we identified a c.1367delG mutation(p.Arg456fs) in CHST15 (NM_001270764), a gene encoding a type II transmembraneglycoproteinthat acts as a sulfotransferase and participates in the biosynthesis of chondroitin sulfate E, in germline and somatic cells in familial MPN. CHST15defects caused an increased JAK2V617F allele burden and upregulated p-Stat3 activity,leading to an increase in the proliferative and prodifferentiation potential of transgenic HEL cells. We demonstrated that mutant CHST15 is able to coimmmunoprecipitate the JAK2 protein,suggesting the presence of a CHST15-JAK2-Stat3 signaling axis in familial MPN. Gene expression profiling showed that the FREM1, IFI27 and C4B_2 genes are overexpressed in familial MPN, suggesting the activation of an “inflammatory response-extracellular matrix-immune regulation” signaling network in the CHST15 mutation background.We thus concluded that CHST15 is a novel gene that predisposes to familial MPN and increases the probability of disease development or transformation.

S196: ROPEGINTERFERON ALFA-2B ACHIEVES PATIENT-SPECIFIC TREATMENT GOALS IN POLYCYTHEMIA VERA: FINAL RESULTS FROM THE PROUD-PV/CONTINUATION-PV STUDIES

Background: Treatment of polycythemia vera (PV) aims to prevent thromboembolic complications, reduce the risk of progression to acute leukemia or myelofibrosis - of particular concern to patients - and ameliorate the symptom burden; specifically, to improve quality of life, therapy should address the most clinically important symptoms while reducing phlebotomies to avoid iron-deficiency symptoms. Long-term efficacy and safety of ropeginterferon alfa-2b have been demonstrated in PROUD-PV/CONTINUATION-PV; the final analysis applied a patient-focused approach. Aims: To analyze the patient-relevant benefit of ropeginterferon alfa-2b versus hydroxyurea (HU)/best available treatment (BAT) over 6 years. Methods: Patients diagnosed with PV according to WHO 2008 criteria who were cytoreduction-naïve or hydroxyurea pre-treated and gave written informed consent were randomized 1:1 to ropeginterferon alpha-2b or control treatment (HU) for one year in PROUD-PV. In CONTINUATION-PV, control arm patients could switch from HU to BAT. Patient-reported PV symptom burden was assessed based on adverse events documented in the patient diary and recorded at each visit; items defined in the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-SAF TSS; fatigue, concentration problems, early satiety, inactivity, night sweats, itching, bone pain, abdominal discomfort, weight loss, and fevers) and medical synonyms were evaluated post-hoc. Efficacy assessments included Kaplan-Meier analysis of event-free survival, phlebotomy need and JAK2V617F allele burden. Analyses were conducted on the CONTINUATION-PV full analysis set over 6 years of treatment. Results: The full analysis set comprised 95 patients in the ropeginterferon alfa-2b arm and 74 in the control arm. Patient-reported symptoms defined in the MPN-SAF TSS were present in a small minority (9.5%) of patients per arm at baseline (up to Week 4 of treatment) in this early-stage PV population. Occurrence of the defined symptoms remained low over long-term treatment, reported in 15.7% of patients in the ropeginterferon alfa-2b arm and 20.7% in the control arm during the 6th year of treatment. No phlebotomies were required to maintain hematocrit <45% in the 6th year of treatment in 81.4% of patients receiving ropeginterferon alfa-2b compared with 60.0% of patients in the control arm (p=0.005). Depletion of the JAK2V617F alle burden, which may lower the risk of progression to myelofibrosis, was observed in ropeginterferon alfa-2b treated patients; JAK2V617F allele burden <1% at 6 years was achieved in 19/92 (20.7%) patients in the ropeginterferon alfa-2b arm with baseline allele burden >10%. One patient met this threshold in the control arm (1/70 [1.4%]; p=0.0001). Event-free survival (risk events: disease progression, death and thromboembolic events) over ≥6 years of treatment was significantly higher among ropeginterferon alfa-2b treated patients than the control group (risk events reported in 5/95 vs. 12/74 patients, respectively; p=0.04 [Log-Rank]; Fig 1). Image:Summary/Conclusion: Long-term ropeginterferon alfa-2b therapy fulfils treatment goals important to patients with PV: a good quality of life as indicated by a low symptom burden and phlebotomy requirement, the potential to influence myelofibrosis risk, and better event-free survival versus BAT.

P1016: POLYCYTHEMIA VERA AND IMMUNE THROMBOGENESIS

Background: Polycythemia Vera (PV) is a Ph1-negative myeloproliferative neoplasm characterized by vascular thrombosis and poor survival. The polycythemic thrombogenesis is associated with erythrocytosis and red cell adhesiveness angiopathy. Recent studies reported a JAK/STAT-mediated reduction of the regulatory T cells (Tregs) (CD4+, CD25high, CD127low, FoxP3+) and loss of self-tolerance. Aims: We investigated Tregs, anti-endothelial cell antibodies (AECA), and endothelial, platelet and coagulation activation, in Polycythemia Vera (PV) and thrombosis. Methods: We enrolled 60WHO-defined PV patients (30 men, 30 women; mean age 45±10 years) without cardiovascular risk factors, autoimmune disease or thrombotic history. Of PV patients, 40/60 had thromosis includingmyocardial infarction (MI) (10/60) according to the WHO critera, deep vein thrombosis (20/60) and pulmonary embolism (10/60) on lower-limb ultrasonography and computed tomography angiography, respectively. All patients were evaluated for JAK2V617F allele burden, Tregs, AECA,Endothelial Leukocyte Adhesion Molecule-1 (ELAM-1), Intercellular Adhesion Molecule-1 (ICAM-1),prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fib) and D-dimer (DD). JAK2V617F allele burden were analyzed by Polymerase chain reaction, Tregs were measured by flow cytometry,AECA, ELAM-1 and ICAM-1 by ELISA, PT and APTT by coagulometric test, Fib using Clauss method, and DD using ELISA.Complete blood hemostasis was studied by PFA-100 on Collagen/ADP (CT-ADP) and Collagen/Epinephrine (CT-EPI) cartridges and Thromboelastometry method on Clotting Time (CT), Clotting Formation Time (CFT), Maximum Clot Firmness (MCF), and clot lysis at 30 minutes (LY-30). Results: The patients with thrombosis had JAK2V616F allele burden higher (> 50%) compared to patients without thrombosis (< 50Kroll%), lower Tregs (1,5±0,5% vs 3.5±1%),higher AECA (200±20% vs 110±10%), ELAM-1 (80±10 ng/ml vs 45±5 ng/ml), and ICAM (170 ng/mL±10 vs 110±10 ng/mL), longer PT (30±10 s vs 20±2 s) and PTT (60±10 s vs 38±5 s), lower Fib (90±20 mg/dl vs 120±20 mg/dl), higher DD (650±100 mg/l vs 300±50 mg/l) and shorter C/ADP and C/EPI (C/ADP, n.v. 68-121 s (40±10 s vs 55±20 s) and C/EPI n.v. 84-160 s (35±5 s vs 60±10 s). The patients with thrombosis had shorter CT (INTEM 35±20 s vs 70±20 s, EXTEM 20±10 s vs 30±5 s), shorter CFT (INTEM 15±10 s vs 25±5 s EXTEM 18±10 s vs 28±5 s), longer MCF (INTEM 130±10 mm vs 90±10 mm, EXTEM 120±10 mm vs 82±10 mm), and lower LY-30 (INTEM 0.9% vs 15%, EXTEM 0.8% vs 15%). A positive correlation there was between Tregs and AECA, ELAM-1 and ICAM-1 and thrombosis. Summary/Conclusion: These findings shed new light on thrombotic pathogenesis in patients with PV.

P1026: COMPARATIVE GENOMIC PROFILING OF MYELOPROLIFERATIVE NEOPLASMS PRESENTING WITH AND WITHOUT SPLANCHNIC VEIN THROMBOSIS

Background: Splanchnic vein thrombosis (SVT) is the initial manifestation in 5% of myeloproliferative neoplasms (MPN). MPN patients presenting with SVT are usually younger, have less abnormal blood counts and lower JAK2V617F allele burden than other MPN patients. However, it is unknown whether they have a different genomic background. Aims: To describe the clinical and genomic profile of MPN presenting with SVT and to compare it with a matched group of MPN without SVT. Methods: Samples of 190 MPN patients were selected: 64 MPN presenting with SVT (SVT+) and 126 MPN without SVT (SVT-). SVT+ and SVT- were matched according to sex, age, MPN clinical subtype and driver mutation. Next Generation Sequencing was performed using Myeloid Solution by Sophia Genetics, which includes 30 genes recurrently mutated in MPN. Variants were selected using Sophia DDM software and were subsequently classified into 5 categories: 5 (definitely pathogenic), 4 (likely pathogenic), 3 (uncertain), 2 (likely benign), and 1 (benign). Only variants included into 4 and 5 categories were taken into account. Patients were classified according to the genomic classification proposed by Grinfeld and colleagues. Results: One hundred and three patients were women (54.2%) and 87 patients were men (45.8%), without significant differences between SVT+ and SVT- groups. Median age was 44 years (range: 15-85) and 50 years (range: 15-87) in SVT+ and SVT-, respectively (p not significant). Regarding MPN clinical subtype in SVT+ group, 39 (60.9%), 15 (23.4%) and 10 (15.6%) corresponded to Polycythemia Vera (PV), Essential Thrombocythemia (ET) and MPN unclassifiable, respectively. In the SVT- group, 75 (59.5%) and 51 (40.5%) corresponded to PV and ET, respectively. Genomic classification in the SVT+ and SVT- groups is shown in Table 1. The proportion of patients with high molecular risk (TP53 disruption/aneuploidy, chromatin/spliceosome mutation, or homozygous JAK2 mutation) was 14.1% and 26.2% for SVT+ and SVT-, respectively (p=0.06). Median number of pathogenic mutations was 1 (range: 1-4) in both SVT+ and SVT- groups. Pathogenic mutations in TET2, DNMT3A and ASXL1 were present in 10%, 3.7% and 3.7%, respectively, without significant differences between both groups. With a mean follow-up of 10.1 years for cases and 9.7 years for controls, 27 patients died (13 SVT+ and 14 SVT-). Median survival was 24 years and not reached for SVT+ and SVT-, respectively (p=0.1). On multivariate analysis, SVT+ group showed a higher risk of death (HR: 2.4, 95%CI: 1.1-5.5, p=0.03) after correction by age, sex and genomic classification. Transformation to myelofibrosis and acute leukemia was low and similar in both groups: 4.7% vs. 5.6% for myelofibrosis in SVT+ and SVT-, respectively (p not significant); and 0% vs. 2.4% for acute leukemia (p not significant). On multivariate analysis, patients with TP53 disruption/aneuploidy, chromatin/spliceosome mutation, or homozygous JAK2 showed a higher risk of disease progression to myelofibrosis or acute leukemia (HR: 14.5, 95%CI: 3.1-68.7, p=0.001) regardless of the presence of SVT at diagnosis, age and sex. Image:Summary/Conclusion: MPN presenting with SVT and MPN-matched controls showed a low molecular complexity. Genomic classification was helpful in identifying a small proportion of MPN patients presenting with SVT who are at high risk of disease progression. SVT at MPN diagnosis is associated with a higher risk of death independent of sex, age and genomic classification.

Resurgence of myeloproliferative neoplasm in patients in remission from blast transformation after treatment with hypomethylating agents

Subsequent blast (BP) or accelerated phase (AP) is a severe complication of Philadelphia-negative myeloproliferative neoplasms (MPNs). The prognosis is generally dismal, but hypomethylating agents (HMAs) may induce a long-lasting response in a minority of patients. Here, we report a cohort of six patients with BP/AP-MPN who experienced MPN relapse after a leukemia response was obtained with azacytidine. Five of the patients achieved complete remission despite the presence of characteristics associated with poor prognosis, such as complex and monosomal karyotypes, TP53 mutations, and EVI1 overexpression. These remissions persisted for over five years in four of the 6 patients. All patients showed rapid reemergence of MPN within a median of two months with thrombocytosis requiring the addition of anagrelide, hydroxyurea, or ruxolitinib given continuously in parallel with the azacytidine cycle. Serial JAK2 V617F allelic burden measurements showed little variation. Thromboembolic events occurred in 3 patients, one leading to death. These findings confirm that HMA may reverse the disease course in AP/BP-MPN to a more chronic phase that may last for years but also lead to morbidity and mortality. Combining maintenance therapy with HMA and MPN-specific drugs appears to be a possible approach to avoiding leukemia relapse and controlling MPN disease.

Impact of Anti-Endothelial Cell Antibodies (AECAs) in Patients with Polycythemia Vera and Thrombosis.

Polycythemia vera (PV) causes thrombosis. Erythrocytosis and cell adhesiveness are responsible for thrombosis. JAK2V617F causes inflammation and autoimmunity; however, whether or not autoimmunity or inflammation causes thrombosis has yet to be proven. In 60 PV patients, we analyzed JAK2V671F and its allele burden, autoimmune Th17 cells, interleukin-17 (IL-17), anti-endothelial cell antibodies (AECAs), endothelial leukocyte adhesion molecule-1 (ELAM-1), intercellular adhesion molecule-1 (ICAM-1), and von Willebrand factor antigen (VWF:Ag). Fifty blood donors were used as the controls. All patients were on phlebotomy-maintaining hematocrit <45% and aspirin. Of the 60 patients, 40 had thrombosis. Those patients with thrombosis had a higher JAK2V617F allele burden than those without thrombosis, andTh17 cells and IL-17 were also higher in patients with thrombosis. Interestingly, we observed a high AECA IgG ELISA ratio (ER) in patients with thrombosis, which was normal in patients without thrombosis. We found high ELAM-1 and ICAM-1 as well as high VWF:Ag in patients with thrombosis compared to patients without thrombosis. AECA-positive sera from patients with thrombosis showed enhanced binding to cytokine-treated HUVEC and a positive antibody-dependent cellular cytotoxicity, suggesting that AECA may contribute to vascular injury. A positive correlation between AECAs, allele burden, and thrombosis was found. These results suggest that autoimmunity may be an additional mechanism in PV thrombogenesis.

JAK2V617F Is a Risk Factor for TIA/Stroke in Young Patients.

The objective of this study was to assess the risk of arterial thrombosis in patients who harbor the JAK2V617F allele burden ≥1% detected during workup for myeloproliferative neoplasms (MPNs). We conducted a large cross-sectional analysis consisted of 5,220 patients who were tested for JAK2V617F and 1,047,258 people matched in age from health care insurance provider, taking into account age, sex, hypertension, diabetes, atrial fibrillation. Compared with noncarriers, mutation carriers were older, less likely to be current or past smokers and had lower body mass index. There was no significant difference between the groups regarding myocardial infarction and peripheral vascular disease. However, JAK2V617F ≥1% at age 34 to 54 years was associated with eightfold more likely to have transient ischemic attack (TIA)/stroke history unrelated to hypertension, diabetes, or atrial fibrillation. Association of JAK2V617F with TIA/stroke was also observed in the older age group, albeit a weaker association and not statistically significant. Prevalence of TIA/stroke was higher in patients with JAK2V617F negative, with odds ratio of 3.93 when compared with the general population after confounder adjustments. Further research is warranted to verify the relation between allele burden of JAK2V617F mutation and TIA/stroke and the role of JAK2V617F per se as a risk factor for arterial thrombosis in the absence of overt MPN. Also, consideration should be paid to the screened group with JAK2V617F negative due to the high incidence of TIA/stroke among them in comparison to the general population.

Treatment and clinical endpoints in polycythemia vera: seeking the best obtainable version of the truth

AbstractPolycythemia vera (PV) is a Philadelphia chromosome-negative myeloproliferative neoplasm driven by the JAK2 V617F (or rarely exon 12) mutation. Its natural history can extend over a few decades, and therefore treatment planning is predicated on continual reassessment of traditional risk features (age, prior thrombosis) to evaluate the need for cytoreduction besides foundational therapy with low-dose aspirin and stringent phlebotomy. Shorter- and longer-term patient goals should be considered in light of several variables such as comorbid conditions (especially cardiovascular risk factors), disease symptoms, and the risk-benefit profile of available drugs. While hydroxyurea has been the pro forma choice of cytoreduction for many practitioners over the last half-century, the more recent regulatory approvals of ruxolitinib and ropeginterferon-alfa-2b, based on phase 3 randomized trials, highlight an expanding portfolio of active drugs. Obtaining high-level evidence for short-term clinical trial endpoints such as hematocrit control, symptom burden/quality of life, splenomegaly, and JAK2 V617F allele burden lies within the timeline of most studies. However, in many cases, it may not be possible to adequately power trials to capture significant differences in the typically low event rates of thrombosis as well as longer-horizon endpoints such as evolution to myelofibrosis and acute myeloid leukemia and survival. This Perspective highlights the challenges of addressing these data gaps and outstanding questions in the emerging treatment landscape of PV.

Increased platelet thrombus formation under flow conditions in whole blood from polycythaemia vera patients.

Polycythaemia vera is a myeloproliferative neoplasm characterised by a high incidence of thrombosis. The contribution of platelets, key players in haemostasis, in this setting is still unclear. So far, the majority of studies have been focussed on specific platelet abnormalities but not on their actual capacity to form thrombi. The aim of this study was to characterise, ex vivo under flow conditions, the capacity of platelets from patients with polycythaemia vera to adhere to collagen and induce thrombus formation. Thirty-nine patients and 30 healthy controls were studied. Thrombus formation was induced by perfusing whole blood over a collagen-coated surface, in a parallel-plate flow chamber coupled to a fluorescent microscope. This dynamic system enables platelet adhesion and thrombus formation to be followed in real time and also allows measurements of the extent of the thrombus and platelet surface antigen expression. Laboratory data were analysed in the light of the patients' main haematological parameters and therapies. Platelet adhesion was significantly greater in patients than in control subjects. Patient thrombi were usually larger and more complex than those formed by control platelets. A significant positive correlation was found between platelet adhesion and both the haematocrit and red blood cell count. These parameters remained significantly correlated with platelet adhesion also after multivariable analysis adjusted for gender, age, therapy and JAK2V617F allele burden. Furthermore, subjects with a haematocrit >45% had significantly greater platelet adhesion than subjects with a haematocrit <45%. Our data indicate that increased platelet adhesion participates in the thrombotic diathesis of patients with polycythaemia vera, and that the haematocrit level can affect the adhesive and thrombus forming capacities of platelets.

JAK2 allele burden is correlated with a risk of venous but not arterial thrombosis

BackgroundThrombosis is the main complication in myeloproliferative neoplasms (MPN). A JAK2V617F mutation has been shown to be a risk factor for thrombosis. The implication of other risk factors alongside a mutation allele burden needs to be clarified (Trifa et al., 2018; Borowczyk et al., 2015). ObjectiveOur aim was to investigate the role of the JAK2 mutation allele burden in the risk of cardiovascular events (CVE) and/or venous thrombosis (VTE) in a cohort of patients with confirmed MPN, as well as in patients without confirmed MPN. MethodsWe restrospectively included all consecutive patients who were positive for JAK2V617F seen by our unit between December 2008 and September 2016. Inclusion criteria were a positive test for the JAK2V617F mutation, with at least 1% allele burden, with or without confirmed MPN. ResultsWe included 239 patients of median age 71 years [60–81], followed-up for a median of 82.8 months [41.08–146.88]. For JAK2V617F positive patients having an allele burden superior to 50% the cumulative incidence of VTE was significantly higher than for those with an allele burden inferior to 50% (HR 3.11 95% CI [1.10–8.76] p = 0.031). The cumulative incidence of VTE was also higher in patients with obesity (HR 4.58 95% CI [1.33–15.8] p = 0.016). There was no significant association between a JAK2V617F allele burden and arterial thrombosis (manifesting as CVE). Previous VTE was also associated with a higher cumulative incidence of recurrence during follow-up HR 3.22 95% CI [1.17–8.81] p = 0.0231. ConclusionWe show that a JAK2V617F allele burden is associated with risk of VTE but not with CVE.

Evaluation of the correlation between JAK2V617F allele burden by Quenching Probe-Tm method and allele-specific quantitative PCR method

The JAK2V617F mutation is a driver mutation of myeloproliferative neoplasms (MPNs). V617F allele burden is considered a risk factor for complications associated with MPNs and is a predictor of prognosis. In Japan, V617F allele burden has been measured in laboratory settings using the i-densyTM IS-5320 genetic analyzer with the quenching probe-Tm (QP-Tm) method. However, since 2020, allele-specific quantitative PCR (AS-qPCR) is being performed in clinical settings for measuring V617F allele burden. To investigate the clinical usefulness of the QP-Tm method in patients with MPNs, we evaluated the V617F allele burden measured by both the methods. A good correlation was observed between the V617F allele burden determined using QP-Tm and that determined using AS-qPCR (P<0.001, rs=0.952). The median mutant allele burden, as determined using the QP-Tm method, was significantly higher in patients with polycythemia vera than in those with essential thrombocythemia. The results of this study suggested that the QP-Tm method will continue to be useful clinical ancillary test for measuring V617F allele burden.

Clinical features and outcomes of JAK2 V617F-positive polycythemia vera and essential thrombocythemia according to the JAK2 V617F allele burden.

BackgroundJAK2 mutation status is a well-known risk factor for thrombosis in patients with myeloproliferative neoplasms. However, the clinical usefulness of JAK2 V617F allele burden is under investigation.MethodsWe retrospectively evaluated the impact of the JAK2 V617F allele burden on clinical characteristics and outcomes of JAK2 V617F-positive polycythemia vera (PV) and essential thrombocythemia (ET). The JAK2 V617F allele burden was measured using sequencing.ResultsAltogether, 127 patients with JAK2 V617F mutation (PV, N=61; ET, N=66) were included in this study. JAK2 V617F allele burdens were positively correlated with white blood cell counts, hemoglobin values, lactate dehydrogenase levels, and platelet counts. The median values of JAK2 V617F allele burden in patients with PV and ET were 58% and 30%, respectively. A JAK2 V617F allele burden of ≥30%, older age, and a higher hemoglobin level were risk factors for thrombotic events in ET. In patients with PV, older age was the only thrombotic risk factor. The 8-year probabilities of overall survival (OS) were 82.9% in all patients. A high JAK2 V617F allele burden (≥58%) was associated with poor OS in patients with PV. For the patients with ET, the difference in 8-year OS based on the JAK2 V617F allele burden was not significant.ConclusionThe JAK2 V617F allele burden was correlated with hematologic parameters and clinical outcomes. Assessing the JAK2 V617F allele burden can be helpful in predicting the thrombotic risk and disease course in patients with JAK2 V617F-positive PV and ET.