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Original Article

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Blood Res 2021; 56(4):

Published online December 31, 2021

https://doi.org/10.5045/br.2021.2021089

© The Korean Society of Hematology

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

A-Jin Lee1, Sang-Gyung Kim1, Jun Yeb Nam2, Jaehum Yun2, Hun-Mo Ryoo2, Sung Hwa Bae2

Author Info. +

1Department of Laboratory Medicine, 2Division of Hematology/Oncology, Department of Internal Medicine, Daegu Catholic University Hospital, Daegu Catholic University School of Medicine, Daegu, Korea

Correspondence to : Sung Hwa Bae, M.D., Ph.D.
Division of Hematology/Oncology, Department of Internal Medicine, Daegu Catholic University Hospital, Daegu Catholic University School of Medicine, 33, Duryugongwon-ro 17-gil, Nam-gu, Daegu 42472, Korea
E-mail: sunghwa@cu.ac.kr

Received: April 26, 2021; Revised: August 3, 2021; Accepted: September 8, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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Background
JAK2 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.
Methods
We 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.
Results
Altogether, 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.
Conclusion
The 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.

Keywords JAK2, Thrombosis, Polycythemia, Thrombocythemia, Essential thrombocythemia, Polycythemia vera

Article

Original Article

Blood Res 2021; 56(4): 259-265

Published online December 31, 2021 https://doi.org/10.5045/br.2021.2021089

Copyright © The Korean Society of Hematology.

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

A-Jin Lee1, Sang-Gyung Kim1, Jun Yeb Nam2, Jaehum Yun2, Hun-Mo Ryoo2, Sung Hwa Bae2

1Department of Laboratory Medicine, 2Division of Hematology/Oncology, Department of Internal Medicine, Daegu Catholic University Hospital, Daegu Catholic University School of Medicine, Daegu, Korea

Correspondence to:Sung Hwa Bae, M.D., Ph.D.
Division of Hematology/Oncology, Department of Internal Medicine, Daegu Catholic University Hospital, Daegu Catholic University School of Medicine, 33, Duryugongwon-ro 17-gil, Nam-gu, Daegu 42472, Korea
E-mail: sunghwa@cu.ac.kr

Received: April 26, 2021; Revised: August 3, 2021; Accepted: September 8, 2021

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background
JAK2 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.
Methods
We 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.
Results
Altogether, 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.
Conclusion
The 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.

Keywords: JAK2, Thrombosis, Polycythemia, Thrombocythemia, Essential thrombocythemia, Polycythemia vera

Fig 1.

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Figure 1.Survival according to JAK2 V617F allele burden. Overall survival (OS) in patients with PV (A), thrombosis free survival (TFS) in patients with PV (B), OS in patients with ET (C), TFS in patients with ET (D).
Blood Research 2021; 56: 259-265https://doi.org/10.5045/br.2021.2021089

Table 1 . Clinical and laboratory characteristics according to myeloproliferative neoplasm subgroupa)..

Total (N=127)JAK2 V617F mutation PV (N=61)JAK2 V617F mutation ET (N=66)
Age at diagnosis, yr69 (27–88)64 (37–88)69 (27–86)
Sex, female75 (59.1%)31 (50.8%)44 (66.7%)
Cardiovascular risk factors
Diabetes mellitus22 (17.3%)12 (19.7%)10 (15.2%)
Hypertension67 (52.8%)32 (52.5%)35 (53.0%)
Dyslipidemia10 (7.9%)6 (9.8%)4 (6.1%)
Smoking, current or ex-smoker5 (4.0%)4 (6.5%)1 (1.5%)
WBC (×109/L)13.4 (4.2–45.4)17.4 (5.1–45.4)12.3 (4.2–45.0)
Hb (g/dL)15 (8–22)18 (11–22)13 (8–17)
Hct (%)46 (24–68)56 (36–68)39 (24–54)
Platelet (×109/L)700 (95–1,934)540 (95–1,490)930 (465–1,934)
LDH (U/L)462 (205–1,141)4 53 (215–1,141)464 (205–929)
JAK2 V617F allele (%)40.0 (5.0–100.0)58.0 (5.0–100.0)30.0 (5.0–100.0)
Thrombosis51 (40.2%)17 (27.9%)34 (51.5%)
At dusgnosis44 (34.6%)14 (23.0%)30 (45.5%)
During follow upb)20 (15.6%)7 (11.5%)13 (19.7%)
Progression to MF5 (3.9%)3 (4.9%)2 (3.0%)

a)Data are presented as median (range) or N (%). b)Median follow-up duration was 71.3 months..

Abbreviations: ET, essential thrombocythemia; LDH, lactate dehydrogenase; MF, myelofibrosis; MPN, myeloproliferative neoplasm; PV, polycythemia vera; WBC, white blood cell..

Table 2 . Clinical and laboratory characteristics in patients with polycythemia vera according to JAK2 V617F allele burden..

JAK2 V617F allele burden <58% (N=30)JAK2 V617F allele burden ≥58% (N=31)P
Age at diagnosis, yr65 (37–88)63 (45–80)0.880
Sex, females13 (43.3%)18 (58.1%)0.371
WBC (×109/L)13.0 (5.1–27.5)19.0 (9.5–45.4)0.002
Hb (g/dL)18 (11–22)18 (13–22)0.569
Hct (%)56 (36–68)56 (42–65)0.297
Platelet (×109/L)551 (221–1,490)513 (95–1,321)0.902
LDH (U/L)420 (215–940)498 (248–1,141)0.065
Thrombosis0.937
At diagnosis9 (30.0%)5 (16.1%)
During follow up1 (3.3%)5 (16.1%)
Progression to MF1 (3.3%)2 (6.5%)1.000

Data are presented as median (range) or N (%). P-value was determined by Mann-Whitney U test or Chi-square test..

Abbreviations: LDH, lactate dehydrogenase; MF, myelofibrosis; PV, polycythemia vera; WBC, white blood cell..

Table 3 . Clinical and laboratory characteristics in patients with essential thrombocythemia according to JAK2 V617F allele burden..

JAK2 V617F allele burden <30% (N=34)JAK2 V617F allele burden ≥30% (N=32)P
Age at initial diagnosis, yr68 (27–82)72.5 (49–86)0.003
Sex, females22 (64.7%)22 (68.8%)0.931
WBC (×109/L)11.1 (4.2–30.3)14.0 (6.7–45.0)0.035
Hb (g/dL)13 (8–17)13 (9–17)0.949
Hct (%)39 (24–49)39 (31–54)0.380
Platelet (×109/L)859 (465–1,934)966 (517–1,729)0.420
LDH (U/L)391 (205–872)514.5 (240–929)0.049
Thrombosis11 (32.4%)23 (71.9%)0.003
At diagnosis10 (29.4%)20 (62.5%)
During follow up4 (11.8%)9 (28.1%)
Progression to MF0 (0.0%)2 (6.2%)0.446

Data are presented as median (range) or N (%). P-value was determined by Mann-Whitney U test or Chi-square test..

Abbreviations: ET, essential thrombocythemia; LDH, lactate dehydrogenase; MF, myelofibrosis; WBC, white blood cell..

Table 4 . Results of univariate logistic regression analysis for thrombosis..

PV (N=61)ET (N=66)
Odds ratio95% CIPOdds ratio95% CIP
Age at diagnosis, yr1.081.01–1.150.0181.030.99–1.070.106
Sex, females0.580.19–1.810.3511.580.56–4.460.385
JAK2 V617F allele (%)1.000.98–1.030.7421.051.01–1.080.006
WBC (×109/L)1.001.00–1.000.5141.001.00–1.000.671
Hb (g/dL)0.870.69–1.090.2221.260.98–1.630.069
Hct (%)0.950.88–1.030.1961.101.01–1.210.031
Platelet (×109/L)1.001.00–1.000.1351.001.00–1.000.404
LDH (U/L)1.001.00–1.000.1621.001.00–1.010.075

Variables with P<0.2 were adapted to the multivariate analysis..

Abbreviations: ANC, absolute neutrophil count; ET, essential thrombocythemia; PV, polycythemia vera; WBC, white blood cell..

Table 5 . Results of multivariate logistic regression analysis for thrombosis..

Odds ratio95% CIP
PV
Age at diagnosis1.101.00–1.210.045
ET
Age at diagnosis1.081.01–1.150.022
Hb1.791.10–2.910.019
JAK2 V617F allele burden1.051.00–1.100.039

Abbreviations: CI, confidence interval; ET, essential thrombocythemia; PV, polycythemia vera..
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