The Pitfalls of Global Hemostasis Assays in Myeloproliferative Neoplasms and Future Challenges

Venous and arterial thromboembolism are major complications of myeloproliferative neoplasms (MPNs), comprising polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Global hemostasis assays, including thrombin generation assay (TGA), rotational thromboelastometry (ROTEM), and thromboelastography (TEG), have been proposed as biomarkers to assess the hypercoagulability and thrombotic risk stratification in MPNs. We performed a systematic literature review on the parameters of TGA, ROTEM, and TEG and their association with thrombotic events and treatment strategies in MPNs. Thirty-two studies (all cross-sectional) were included, which collectively enrolled 1,062 controls and 1,608 MPN patients. Among the 13 studies that reported arterial or venous thrombosis, the overall thrombosis rate was 13.8% with 6 splanchnic thromboses reported. Out of the 27 TGA studies, there was substantial heterogeneity in plasma preparation and trigger reagents employed in laboratory assays. There was a trend toward increased peak height among all MPN cohorts versus controls and higher endogenous thrombin potential (ETP) between ET patients versus controls. There was an overall trend toward lower ETP between PV and PMF patients versus. controls. There were no substantial differences in ETP between JAK2-positive versus JAK2-negative MPNs, prior history versus negative history of thrombotic events, and among different treatment strategies. Of the three ROTEM studies, there was a trend toward higher maximum clot firmness and shorter clot formation times for all MPNs versus controls. The three TEG studies had mixed results. We conclude that the ability of parameters from global hemostasis assays to predict for hypercoagulability events in MPN patients is inconsistent and inconclusive. Further prospective longitudinal studies are needed to validate these biomarker tools so that thrombotic potential could be utilized as a primary endpoint of such studies.

Splanchnic Vein Thrombosis in Myelofibrosis-An Underappreciated Hallmark of Disease Phenotype

Splanchnic vein thrombosis (SVT) encompasses thrombosis in the vessels of the splanchnic basin and has a relatively rare occurrence with a reported frequency in the general population of 1-2%. An episode of seemingly unprovoked SVT almost always triggers a diagnostic work-up for a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN), since atypical site thrombosis is a hallmark of MPN-associated thrombophilia. Primary myelofibrosis (PMF) is a rare MPN with an estimated incidence between 0.1 and 1/100,000 per year. Although prothrombotic tendency in PMF is not envisioned as a subject of specific therapeutic management, unlike other MPNs, such as polycythemia vera (PV) and essential thrombocythemia (ET), thrombotic risk and SVT prevalence in PMF may be comparably high. Additionally, unlike PV and ET, SVT development in PMF may depend more on procoagulant mechanisms involving endothelium than on blood cell activation. Emerging results from registry data also suggest that PMF patients with SVT may exhibit lower risk and better prognosis, thus highlighting the need for better thrombotic risk stratification and identifying a subset of patients with potential benefit from antithrombotic prophylaxis. This review highlights specific epidemiological, pathogenetic, and clinical features pertinent to SVT in myelofibrosis.

A Journey Through JAK Inhibitors for the Treatment of Myeloproliferative Diseases

PURPOSE OF REVIEW

Chronic myeloproliferative neoplasms (MPN) represent a group of diseases characterised by constitutive activation of the JAK/STAT pathway in a clonal myeloid precursor. The therapeutic approach aims to treat the symptom burden (headache, itching, debilitation), splenomegaly, slow down the fibrotic proliferation in the bone marrow and reduce the risk of thrombosis/bleeding whilst avoiding leukaemic transformation.

RECENT FINDINGS

In recent years, the advent of JAK inhibitors (JAKi) has significantly broadened treatment options for these patients. In myelofibrosis, symptom control and splenomegaly reduction can improve quality of life with improved overall survival, not impacting progression into acute leukaemia. Several JAKi are available and used worldwide, and combination approaches are now being explored. In this chapter, we review the approved JAKi, highlighting its strengths, exploring potential guidelines in choosing which one to use and reasoning towards future perspectives, where the combinations of therapies seem to promise the best results.

Labor market affiliation of patients with myeloproliferative neoplasms: a population-based matched cohort study

BACKGROUND

Patients with myeloproliferative neoplasms (MPNs) suffer from substantial symptoms and risk of debilitating complications, yet observational data on their labor market affiliation are scarce.

MATERIAL AND METHODS

We conducted a descriptive cohort study using data from Danish nationwide registries, including patients diagnosed with MPN in 2010-2016. Each patient was matched with up to ten comparators without MPN on age, sex, level of education, and region of residence. We assessed pre- and post-diagnosis labor market affiliation, defined as working, unemployed, or receiving sickness benefit, disability pension, retirement pension, or other health-related benefits. Labor market affiliation was assessed weekly from two years pre-diagnosis until death, emigration, or 31 December 2018. For patients and comparators, we reported percentage point (pp) changes in labor market affiliation cross-sectionally from week -104 pre-diagnosis to week 104 post-diagnosis.

RESULTS

The study included 3,342 patients with MPN and 32,737 comparators. From two years pre-diagnosis until two years post-diagnosis, a larger reduction in the proportion working was observed among patients than comparators (essential thrombocythemia: 10.2 [95% CI: 6.3-14.1] vs. 6.8 [95% CI: 5.5-8.0] pp; polycythemia vera: 9.6 [95% CI: 5.9-13.2] vs. 7.4 [95% CI: 6.2-8.7] pp; myelofibrosis: 8.1 [95% CI: 3.0-13.2] vs. 5.8 [95% CI: 4.2-7.5] pp; and unclassifiable MPN: 8.0 [95% CI: 3.0-13.0] vs. 7.4 [95% CI: 5.7-9.1] pp). Correspondingly, an increase in the proportion of patients receiving sickness benefits including other health-related benefits was evident around the time of diagnosis.

CONCLUSION

Overall, we found that Danish patients with essential thrombocythemia, polycythemia vera, myelofibrosis, and unclassifiable MPN had slightly impaired labor market affiliation compared with a population of the same age and sex. From two years pre-diagnosis to two years post-diagnosis, we observed a larger reduction in the proportion of patients with MPN working and a greater proportion receiving sickness benefits compared with matched individuals.

Diagnosis and treatment of MPN in real life: exploratory and retrospective chart review including 960 MPN patients diagnosed with ET or MF in Germany

PURPOSE

The WHO 2016 re-classification of myeloproliferative neoplasms resulted in a separation of essential thrombocythemia (ET) from the pre-fibrotic and fibrotic (overt) phases of primary myelofibrosis (MF). This study reports on a chart review conducted to evaluate the real life approach regarding clinical characteristics, diagnostic assessment, risk stratification and treatment decisions for MPN patients classified as ET or MF after implementation of the WHO 2016 classification.

METHODS

In this retrospective chart review, 31 office-based hematologists/oncologists and primary care centers in Germany participated between April 2021 and May 2022. Physicians reported available data obtained from patient charts via paper-pencil based survey (secondary use of data). Patient features were evaluated using descriptive analysis, also including diagnostic assessment, therapeutic strategies and risk stratification.

RESULTS

Data of 960 MPN patients diagnosed with essential thrombocythemia (ET) (n = 495) or myelofibrosis (MF) (n = 465) after implementation of the revised 2016 WHO classification of myeloid neoplasms was collected from the patient charts. While they met at least one minor WHO-criteria for primary myelofibrosis, 39.8% of those diagnosed with ET did not have histological BM testing at diagnosis. 63.4% of patients who were classified as having MF, however, did not obtain an early prognostic risk assessment. More than 50% of MF patients showed characteristics consistent with the pre-fibrotic phase, which was emphasized by the frequent use of cytoreductive therapy. Hydroxyurea was the most frequently used cytoreductive medication in 84.7% of ET and 53.1% of MF patients. While both ET and MF cohorts showed cardiovascular risk factors in more than 2/3 of the cases, the use of platelet inhibitors or anticoagulants varied between 56.8% in ET and 38.1% in MF patients.

CONCLUSIONS

Improved histopathologic diagnostics, dynamic risk stratification including genetic risk factors for cases of suspected ET and MF are recommended for precise risk assessment and therapeutic stratification according to WHO criteria.

Integrated Approach to Highlighting the Molecular Bases of a Deep Vein Thrombosis Event in an Elite Basketball Athlete

Acute or intense exercise can result in metabolic imbalances, muscle injuries, or reveal hidden disorders. Laboratory medicine in sports is playing an increasingly crucial role in monitoring athletes' health conditions. In this study, we designed an integrated approach to explore the causes of a deep venous thrombosis event in an elite basketball player. Since the complete blood count revealed a marked platelet count (838 × 103 µL), and thrombophilia screening tests did not reveal any significant alteration, we evaluated the thrombin generation, which highlights a state of hypercoagulability. First-level haemostasis exams showed only a slight prolongation of the activated Partial Thromboplastin Time (aPTT). Thus, screening tests for von Willebrand Disease showed a reduction in vWF parameters. Therefore, we directed our hypothesis towards a diagnosis of acquired von Willebrand disease secondary to Essential Thrombocythemia (ET). To confirm this hypothesis and highlight the molecular mechanism underlying the observed phenotype, molecular tests were performed to evaluate the presence of the most common mutations associated with ET, revealing a 52-bp deletion in the coding region of CALR exon 9. This case report highlights the importance of an integrated approach to monitoring the athletes' health status to personalise training and treatments, thus avoiding the appearance of diseases and injuries that, if underestimated, can undermine the athlete's life.

Increased levels of a subset of angiogenesis-related plasma proteins in essential thrombocythemia

Background: Increased local angiogenesis is important for the growth and dissemination of cancer. The myeloproliferative neoplasm essential thrombocythemia (ET) is known to involve increased bone marrow angiogenesis. Blood levels of several angiogenesis-related proteins are increased in different types of cancer. The aim of this study was to investigate whether a subset of such proteins was elevated in treatment-naïve ET patients. Methods: Blood plasma from 41 ET patients and 43 healthy aged-matched controls was analyzed for eight different angiogenesis-related proteins. Results: The ET cohort displayed a more homogenous expression pattern of these proteins compared with controls. Five of the eight proteins were significantly increased in ET patients. Conclusion: Increased plasma levels of matrix metallopeptidase 9 (MMP9) and endostatin have not previously been reported in ET. In our patients, MMP9 levels correlated positively with Janus kinase 2 (JAK2) V617F allele burden and leukocyte count.

Second malignancies among older patients with classical myeloproliferative neoplasms treated with hydroxyurea

Patients with classical Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary and secondary myelofibrosis (MF), are known to have an increased risk of second malignancies (SMs). Hydroxyurea (HU) is a guideline-recommended cytoreductive therapy for patients at high risk for MPNs. Controversy exists as to whether HU use is associated with a higher risk of SMs, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We conducted a retrospective cohort study of older patients diagnosed with MPN (age ≥66 years) between 2010 and 2017 and included the data in the Surveillance, Epidemiology, and End Results Medicare-linked database. Multivariable competing risk analyses adjusting for patient characteristics were used to assess the impact of HU on the development of SM. We identified 4023 patients (1688 with PV, 1976 with ET, and 359 with MF) with a median age of 77 (interquartile range [IQR], 71-83) years at the time of MPN diagnosis. After a median follow-up of 3.25 (IQR, 2.10-5.00) years, 489 patients developed an SM (346 solid, 73 lymphoid, and 70 myeloid malignancies). The cumulative incidence probability of SM was 19.88% (95% confidence interval [CI], 17.16%-22.75%) among 2683 HU users and 22.31% (95% CI, 17.51%-27.47%) among 1340 nonusers, respectively (Gray's test, P < .01). We did not identify significant differences in the incidence of solid or hematologic SMs, including AML/MDS (hazard ratio, 1.33; 95% CI, 0.77-2.29; P = .30), between HU users and nonusers. Our results suggest that the use of HU does not increase the risk of SM in older patients with MPN.

Lower CXCR3 expression in both patients with neovascular AMD and advanced stages of chronic myeloproliferative blood cancers

Purpose

Peripheral T cell CXCR3 expression has been found uniquely lower in patients having neovascular age-related macular degeneration (nAMD) than in healthy individuals. The CXCR3-axis has been shown to have angiostatic and antifibrotic properties. We have recently investigated systemic markers in patients with myeloproliferative neoplasms (MPNs) because of their higher prevalence of AMD, and we have observed higher systemic chronic low-grade inflammation and immunosenescence signs in MPNs with drusen (MPNd) compared to those with normal retinas (MPNn). The MPNs evolve in a biological continuum from early cancer-stages (essential thrombocytosis, polycythemia vera) to the advanced myelofibrosis stage. Especially myelofibrosis is characterized by bone marrow angiogenesis and fibrosis, similarly to retinal observations in nAMD. We speculate if we can find lower CXCR3 expression in MPNs, particularly myelofibrosis and if differences are seen between MPNd and MPNn. We also wanted to compare expression in nAMD and intermediate (i)AMD.

Methods

Patients in this cross-sectional study were 29 nAMD, 28 iAMD, 35 MPNd, and 27 MPNn. We performed flowcytometry on blood to measure CXCR3 expression.

Results

CD8+CXCR3 expression in nAMD was 6,1%, significantly lower than in iAMD 16%, MPNd 11%, MPNn 12% (p-values<0.05). Similar results were seen for CD4+CXCR3 expression. We also found CXCR3 expression decreasing over the MPN-continuum. For instance, in myelofibrosis, intermediate monocytes expression was 6.2%, significantly lower than 18% in ET and 18% in PV (p-values<0.05).

Conclusions

We find CXCR3 downregulation on T-cells and some monocyte subset in nAMD compared to iAMD, MPNd, and MPNn, in line with previous nAMD studies. We also find CXCR3 downregulation in most monocyte subsets over the MPN continuum. Systemic leukocyte CXCR3 expression could both be involved in changes seen in the retina and the bone marrow. Further understanding the CXCR3-axis in AMD and MPNs may elucidate underlying pathogenic mechanisms and reveal new targets for treatment.

[Clinical Analysis of Gene Mutation and Vascular Events in Patients with BCR/ABL Negative Myeloproliferative Neoplasms]

OBJECTIVE

To explore the relationship between clinical features, peripheral blood cell count, coagulation function, gene mutation and hemorrhagic events and thrombotic events in essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis(PMF) patients.

METHODS

Clinical data of 78 patients with ET, PV, and PMF who were admitted to the Second Affiliated Hospital of Chongqing Medical University between September 2019 and August 2020 were retrospectively analyzed. Information about sex, age, gene mutation, peripheral blood cell count, coagulation function, and hemorrhagic and thrombotic events was included, and the influence of these data on the occurrence of hemorrhagic and thrombotic events was estimated.

RESULTS

Among the 78 patients with myeloproliferative neoplasms, there were 47 cases of ET, 15 cases of PV, and 16 cases of PMF.A total of 10 patients (12.82%) experienced hemorrhagic events and 27 (34.62%) experienced thrombotic events. Male,patients aged ≥ 60 years, and patients with a JAK2V617F mutation were more likely to experience thrombotic events (P<0.05). Patients with thrombotic events had higher platelet (PLT) counts and fibrinogen (FIB) levels than patients without hemorrhagic-thrombotic events (P<0.05).White blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (HGB) level, prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and international normalized ratio (INR) showed no statistical difference between patients with thrombotic events and patients without hemorrhagic-thrombotic events (P>0.05). There was also no significant difference in the above-mentioned indexes between patients with hemorrhagic events and patients without hemorrhagic-thrombotic events (P>0.05). Among JAK2V617F positive myeloproliferative neoplasm patients, male patients were more likely to have thrombotic events (P<0.05), and patients with thrombotic events had higher platelet counts than those without hemorrhagic-thrombotic events (P<0.05). There was no significant difference in age, white blood cell count, red blood cell count, hemoglobin level, PT, APTT, FIB, TT or INR between patients with thrombotic events and patients without hemorrhagic-thrombotic events (P>0.05).

CONCLUSION

Sex, age, JAK2V617F mutation and platelet count have a certain value for predicting thrombosis in patients with myeloproliferative neoplasms.

[Analysis of Differential Proteins Related to Platelet Activation in Patients with Essential Thrombocythemia Based on Label-Free Quantitative Technology]

OBJECTIVE

To analysis the specific protein markers of essential thrombocythemia (ET) based on proteomics technology, to explore and verify the differential protein related to platelet activation.

METHODS

Blood samples were obtained from ET patients and healthy people and a certain protein mass spectrometry was detected using label-free quantitative technology. The proteins relative abundance increased or down-regulated by 1.3 times in the disease group compared with the control group, and the protein abundance in the two groups t test P＜0.05 were defined as differential proteins. Bioinformatics analysis of the differential proteins was performed using GO and KEGG. The difference in the average protein abundance between the two groups was analyzed by t test and P＜0.05 was considered statistically significant. Differential proteins were selected for verification by parallel reaction monitoring (PRM) technology.

RESULTS

A total of 140 differential proteins were found, of which 72 were up-regulated and 68 were down-regulated. KEGG enrichment showed that the differential protein expression was related to the platelet activation pathway. The differential proteins related to platelet activation were GPV, COL1A2, GP1bα, COL1A1 and GPVI. Among them, the expressions of GPV, GP1bα and GPVI were up-regulated, and the expressions of COL1A2 and COL1A1 were down-regulated. PRM verification of COL1A1, GP1bα, GPVI and GPV was consistent with LFP proteomics testing.

CONCLUSION

Differential proteins in ET patients are related to platelet activation pathway activation.Differential proteins such as GPV, GPVI, COL1A1 and GP1bα can be used as new targets related to ET platelet activation.

The impact of JAK2V617F mutation on Philadelphia-negative myeloproliferative neoplasms

BACKGROUND

JAK2V617F mutation is expressed in almost all polycthemia vera (PV), 55% of essential thrombocythemia (ET), and 65% of primary myelofibrosis (PMF) patients. Studies investigating phenotypic effects of JAK2V617F mutation on Philadelphianegative myeloproliferative neoplasms (Ph-negative MPNs) have reported controversial results. This study aims to determine the impact of JAK2V617F mutation on clinical phenotype and outcome in Ph-negative MPNs.

METHODS

Clinical correlates and long-term prognostic relevance of the JAK2V617F mutation were analyzed in 410 Phnegative MPNs-170 ET, 135 PV, 105 PMF- from two institutions and followed for a mean of 76.7 months (SD 62.1) (mean 87 months (SD 67.8), 70.4 months (SD 56.4), 68 months (SD 57.4), respectively for ET, PV, and PMF). Two hundred and twenty-eight patients were genotyped for JAK2V617F mutation using the JAK2 Ipsogen MutaScreen assay, which involves allele-specific polymerase chain reaction (PCR), and 182 patients were genotyped using melting curve analysis.

RESULTS

In PV patients, JAK2V617F mutation was associated with higher rate in females, lower hemoglobin (Hgb) level, higher leukocyte and platelet count and higher prevalence of thrombosis (p = 0.008, p = 0.018, p = 0.001, p = 0.001, and p = 0.035, respectively). In ET patients, JAK2V617F mutation was associated with higher Hgb and hematocrit (Hct) levels and lower platelet count (p = 0.001, p = 0.001, and p = 0.001, respectively). JAK2V617F-negative ET patients showed a trend towards higher rate of leukemic transformation (p = 0.061). JAK2V617F mutation-positive PMF patients had higher leukocyte count, greater spleen size and showed a trend towards higher Hgb level (p = 0.019, p = 0.042, and p = 0.056, respectively). Among PMF patients with JAK2V617F mutation, the rate of female patients was lower (p = 0.001). Overall survival (OS) in Dynamic International Prognostic Scoring System (DIPSS) - plus high risk PMF patients was shorter compared to the other risk groups (p = 0.001). Leukemia-free survival (LFS) was shorter in DIPSS - plus high risk PMF patients than the other risk groups (p = 0.005). In the entire cohort of Ph-negative MPN patients, JAK2V617F mutation was associated with higher leukocyte count, higher Hgb and Hct levels and lower platelet count, higher frequency of phlebotomies, a trend towards older age, a trend towards greater spleen size, a trend towards a higher prevalence of risk factors for cardiovascular diseases and thrombosis (p = 0.001, p = 0.005, p = 0.001, p = 0.003, p = 0.004, p =0.052, p = 0.056, p = 0.052, and p = 0.059, respectively).

[The 491st case: thrombocytosis, gastrointestinal hemorrhage, intestinal perforation]

Essential thrombocythemia (ET) is a chronic myeloproliferative neoplasm (MPN) featured by clonal proliferation of platelets, thrombosis and hemorrhage. Portal hypertension is a serious complication of ET associated with poor prognosis. We report a patient with ET complicated with acute upper gastrointestinal hemorrhage and intestinal perforation due to portal hypertension. She had an uneventful recovery after surgical and endoscopic treatment.

New Horizons in Myeloproliferative Neoplasms Treatment: A Review of Current and Future Therapeutic Options

Philadelphia-negative myeloproliferative neoplasms (MPN) are aggressive diseases characterized by clonal proliferation of myeloid stem cells. The clonal process leads to excessive red cells production, platelets production, and bone marrow fibrosis. According to the phenotype, MPN can be classified as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). MPN patients have shortened survival due to the increased risk of thrombosis, hemorrhages, and transformation to acute myeloid leukemia (AML). Prognosis is variable, with a shorter life expectancy in myelofibrosis. Currently, drug therapy can reduce symptoms, splenomegaly, and risk of thrombosis. Still, some patients can be resistant or intolerant to the treatment. At the same time, allogeneic stem cell transplant (ASCT) is the only treatment modality with the potential to cure the disease. Nevertheless, the ASCT is reserved for high-risk leukemic progression patients due to the risk of treatment-related death and comorbidity. Therefore, there is a need for new drugs that can eradicate clonal hematopoiesis and prevent progression to more aggressive myeloid neoplasms. Thanks to the better understanding of the disease’s molecular pathogenesis, many new potentially disease-modifying drugs have been developed and are currently in clinical trials. This review explores the most promising new drugs currently in clinical trials.

[Analysis of Clinical Characteristics of JAK2 V617F and BCR-ABL Double-Mutant Myeloproliferative Neoplasms]

OBJECTIVE

To analyze the disease types, clinical manifestations, efficacy and outcome of JAK2 V617F and BCR-ABL double-mutant myeloproliferative neoplasms (MPN), and provide a reference for the diagnosis, treatment and prognosis of MPN.

METHODS

The clinical characteristics, diagnosis, therapeutic efficacy and outcome of JAK2 V617F and BCR-ABL double-mutant MPN were analyzed comprehensitively by combining a clinical case diagnosed and treated in our hospital with literature cases from CNKI and PubMed databases.

RESULTS

A total of 38 related literatures were retrieved from the two databases by searching "JAK2 V617F" and "BCR-ABL" as key words from 1990 to 2019, and 59 cases were involved. Among all the 60 cases, 41 were males (68.3%) with a median age of 61 (32-77) years old, while 19 were females (31.7%) with a median age of 58 (21-82) years old. The BCR-ABL fusion gene and JAK2 V617F mutation were found simultaneously in 21 cases (35%), 19 cases (31.7%) with JAK2 V617F mutation were found during the treatment of Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML). Ph⁺CML was detectable in 20 cases (33.3%) during the treatment of JAK2 V617F mutation positive MPN. Polycythemia vera (PV) was the most common MPN coexisting with CML (30%), followed by essential thrombocythemia (ET) (26.7%) and primary myelofibrosis (PMF) (21.7%). In addition, there were 13 cases (21.7%) not classified in the literature. Among the 60 cases, 35 CML patients were clearly staged, including 31 in the chronic phase, 3 in the accelerated phase, and 1 in the blast crisis phase. As for the subtypes of BCR-ABL fusion gene, there were 30 cases with clear classification, including 28 cases of p210, 1 case of p190 and 1 case of p230.

CONCLUSION

As cases of BCR-ABL and JAK2 V617F double-mutant MPN are reported, simultaneous detection of JAK2 V617F mutation and BCR-ABL fusion gene in MPN patients is necessary to avoid misdiagnosis and missed diagnosis.

Phagocytosis by endothelial cells inhibits procoagulant activity of platelets of essential thrombocythemia in vitro

BACKGROUND

Essential thrombocythemia (ET) is characterized by thrombocytosis with increased platelet number and persistent activation. The mechanisms of thrombosis and the fate of these platelets are not clear. The aim of the present study is to explore the phagocytosis of platelets of ET patients by endothelial cells (ECs) in vitro and its relevance to the procoagulant activity (PCA).

METHODS

Phosphatidylserine (PS) exposure on platelets was detected by flow cytometry. Phagocytosis of the platelets by ECs was performed using flow cytometry, confocal microscopy, and electron microscopy. The PCA of platelets was evaluated by coagulation time and purified coagulation complex assays.

RESULTS

The PS exposure on platelets in ET patients is higher than that in healthy controls. The PS-exposed platelets are highly procoagulant and lactadherin reduced 80% of the PCA by blockade of PS. When cocultured, the platelets of ET patients were sequestered by ECs in a time-dependent fashion. Lactadherin enhanced phagocytosis by bridging the PS on activated platelets and the integrin αvβ3 on ECs, and P-selectin played at least a partial role in this process. Furthermore, factor Xa and prothrombinase activity of PS-exposed platelets were decreased after incubation with ECs.

CONCLUSION

Our results suggest that phagocytic clearance of platelets by ECs occurs in ET patients, thus representing a novel mechanism to remove activated platelets from the circulation; lactadherin and phagocytosis could cooperatively limit the thrombophilia in ET patients.

What are the current treatment approaches for patients with polycythemia vera and essential thrombocythemia?

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative neoplasms that are characterized by thrombohemorrhagic complications, symptom burden, and impaired survival mainly due to thrombosis, progression to myelofibrosis, and transformation to acute leukemia. In this manuscript, we will review the most recent changes in diagnostic criteria, the improvements in risk stratification, and the "state of the art" in the daily management of these disorders. The role of conventional therapies and novel agents, interferon α and the JAK2 inhibitor ruxolitinib, is critically discussed based on the results of a few basic randomized clinical studies. Several unmet needs remain, above all, the lack of a curative approach that might overcome the still burdensome morbidity and mortality of these hematologic neoplasms, as well as the toxicities associated with therapeutic agents.

Clinico-Pathological Profile And Outcomes Of Patients With Polycythaemia Vera, Essential Thrombocythaemia And Idiopathic Myelofibrosis: A Tertiary Care Center Experience From Southern Pakistan

BACKGROUND

The "Philadelphia Negative Classic Myeloproliferative Neoplasms" include polycythaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF). These three disorders share several clinical and laboratory features including JAK2 V617F mutation. Our objectives were to determine the clinico-pathological profile and outcomes of Pakistani patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF) in order to have an insight regarding behaviour of these conditions.

METHODS

A retrospective analysis of all the cases of PV, ET and IMF diagnosed at our institute from January 1995 to December 2013 was performed. Age, gender, clinical presentation, laboratory investigations, treatment provided and duration of follow-up were included for analysis. Appropriate statistics were utilized for calculation of data.

RESULTS

A total of 58 patients were diagnosed as PV, ET or IMF during the study period. Male to female ratio was 1.1:1. Forty five percent (n=27) patients came to medical attention due to abnormal laboratory results, 3 had cerebrovascular events, 3 had pruritus, and 1 patient each with gangrene and Budd-Chiari syndrome. Haemorrhage was not seen in any patient. Sixty percent (n=35) patients were treated with phlebotomy, hydroxyurea and aspirin alone or in combination. None of the patients transformed to myelofibrosis (MF) or myelodysplasia (MDS) during the mean (±SD) follow-up period of 57.2±50 months. One patient with ET transformed to acute myeloid leukaemia 9 years after the diagnosis.

CONCLUSIONS

This study demonstrated a relatively more benign form of PV, ET and IMF with lesser frequency of symptoms, good response to treatment and less likelihood of transformation to MF, MDS or AML.

[Analysis of CALR, JAK2 and MPL gene mutations in BCR-ABL negative myeloproliferative neoplasms]

OBJECTIVE

To explore the mutational status of CALR, JAK2 and MPL genes in BCR-ABL negative myeloproliferative neoplasms (MPN) patients and the clinical features of MPN patients with these mutations.

METHODS

A total of 246 patients with a definite diagnosis of BCR-ABL negative MPN were enrolled from January 2009 to January 2014 into this study. Among them, there were 48 cases of polycythemia vera (PV) patients, 171 cases of essential thrombocythemia (ET) patients and 27 cases of primary myelofibrosis (PMF) patients. And CALR, JAK2 V617F, 12 exons of JAK2 and MPL W515L/K genes were amplified by PCR and sequenced directly. Clinical features were also analyzed in patients.

RESULTS

Among 246 cases of BCR-ABL-negative MPN patients, 52 cases (21.1%) had CALR mutation, 121 cases (49.2%) JAK2 V617F mutation, 0 case (0) 12 exons of JAK2 mutation, and 2 cases (0.8%) MPL W515L/K mutation, respectively. These mutations were found existing exclusively. In PV patients, the white blood cell and platelet counts in JAK2 V617F mutated group were higher than those in wild-type JAK2 V617F group, while the level of hemoglobin was higher in wild-type JAK2 V617F group (all P<0.05). In ET patients, the white blood cell count, the level of hemoglobin, the frequency of thromboembolic events and risk stratification in JAK2 V617F mutated group were higher than those in CALR mutated group (all P<0.05). In PMF patients, the level of hemoglobin in JAK2 V617F mutated group were significantly higher than those in CALR mutated group (P<0.05).

CONCLUSIONS

The proliferative level of bone marrow, risk of thromboembolic events and stratification are lower in CALR mutated patients than those in JAK2 V617F mutated patients. The pathogenic mechanism of mutated gene should be further investigated in future.

[JAK2 V617F mutation burden and its clinical implications in 415 patients with myeloproliferative neoplasm]

OBJECTIVE

To detect JAK2 V617F mutation burden and its clinical implications in patients with myeloproliferative neoplasm (MPN).

METHODS

JAK2 V617F mutation burden were detected by using MGB Taqman probes and its clinical significance were retrospectively studied in 415 MPN patients.

RESULTS

JAK2 V617F was found in 56.9% of all patients [83.5% in polycythemia vera (PV), 55.9% in essential thrombocythemia (ET), 41.9% in primary myelofibrosis (PMF) and 64.7% in MPN-unclassifiable)]. The majority of patients carried heterozygous JAK2 V617F mutation and homozygote was found only in 12 cases (4 in PV, 4 in MPN-U, 2 in PMF, 1 in ET, and 1 in chronic neutrophilic leukemia). Most patients (68.8%) were lower mutation burden (mutation burden<50%), but PV had the highest burden, the moderate burden in PMF and the least in ET. The patient's age and WBC count were significantly correlated with higher mutation burden in PV. WBC count was significantly related to higher mutation burden in ET. WBC count, Hb level and the platelet count were significantly related to higher mutation burden in PMF.

CONCLUSION

The mutation burden of JAK2 V617F from high to low was PV, ET and PMF. The majority of JAK2 V617F mutation was heterozygous. JAK2 V617F mutation burden was positively correlated with age, WBC, Hb and platelet counts.

Clinical applications of molecular haematology: JAK2 in myeloproliferative disorders

Molecular markers are helpful in diagnosis, prognosis and management of haematological malignancies. Recently, a single point mutation in the Janus Kinase 2 (JAK2) gene in the Philadelphia-negative myeloproliferative disorders, including polycythemia vera (over 95%), essential thrombocythemia (50%) and primary myelofibrosis (50%) was identified by several groups. This mutation is now considered to have a fundamental role in the pathogenesis of these disorders. A PCR-based test from peripheral blood has become available in India to detect this mutation. Present article discusses the basic aspects of this mutation and its value in diagnosing, prognosticating and treating patients of suspected chronic myeloproliferative disorders.

Thrombosis in myeloproliferative disorders: prevalence, prognostic factors, and the role of leukocytes and JAK2V617F

An underlying myeloproliferative disorder (MPD), especially polycythemia vera (PV) or essential thrombocythemia (ET), is a risk factor for thrombosis. Considering large selected studies, prevalence rates for major thrombosis, at time of diagnosis, range from approximately 34 to 39% for PV and 10 to 29% for ET; the corresponding figures for thrombosis at follow-up are approximately 8 to 19% for PV and 8 to 31% for ET. In all instances, arterial events were more frequent than venous events. In both PV and ET, advanced age and history of thrombosis are independent predictors of recurrent thrombosis. In addition, leukocytosis, but not thrombocytosis, has been identified as a potential risk factor for thrombosis in both diseases. The particular observation is consistent with the laboratory demonstration, in these disorders, of increased number of activated granulocytes and granulocyte-platelet aggregates, upregulation of platelet P-selectin and tissue factor expression by granulocytes, and the antithrombotic value of hydroxyurea therapy. Most recently, a JAK2 gain-of-function mutation ( JAK2V617F) was described in virtually all patients with PV and approximately 50% of those with ET. Whether the presence of this specific mutation or its allele burden modifies the risk of thrombosis in patients with MPDs currently is under investigation.

Cocaine-contaminated allogeneic bone marrow transplantation

Should a person with history of drug addiction be categorically denied as a bone marrow donor? The answer to the question is controversial. We report a case of allogeneic bone marrow transplantation for refractory acute myeloid leukemia preceded by essential thrombocythemia. The donor used cocaine and marijuana the night before the bone marrow harvest.

MAPKAP kinase 2 is activated by heat shock and TNF-alpha: in vivo phosphorylation of small heat shock protein results from stimulation of the MAP kinase cascade

The activation of MAPKAP kinase 2 was investigated under heat-shock conditions in mouse Ehrlich ascites tumor cells and after treatment of human MO7 cells with tumor necrosis factor-alpha (TNF-alpha). MAPKAP kinase 2 activity was determined using the small heat-shock proteins (sHsps) Hsp25 and Hsp27 as substrates. In both cell types, about a threefold increase in MAPKAP kinase 2 activity could be detected in a time interval of about 10-15 min after stimulation either by heat shock or TNF-alpha. Phosphorylation of MAPKAP kinase 2, but not the level of MAPKAP kinase 2 mRNA, was increased after heat shock in EAT cells. It is further shown that activation of MAPKAP kinase 2 in MO7 cells is accompanied by increased MAP kinase activity. These data strongly suggest that increased phosphorylation of the sHsps after heat shock or TNF-alpha treatment results from phosphorylation by MAPKAP kinase 2, which itself is activated by phosphorylation through MAP kinases. Hence, we demonstrate that MAPKAP kinase 2 is responsible not only for phosphorylation of sHsps in vitro but also in vivo. The findings link sHsp phosphorylation to the MAP kinase cascade, explaining the early phosphorylation of sHsp that is stimulated by a variety of inducers such as mitogens, phorbol esters, thrombin, calcium ionophores, and heat shock.

Phosphorothioate oligonucleotides cause degradation of secretory but not intracellular serglycin proteoglycan core protein in a sequence-independent manner in human megakaryocytic tumor cells

Human megakaryocytic tumor cell lines CHRF-288-11 and HEL (human erythroleukemia) were incubated with antisense phosphodiester (PDE) and phosphorothioate (PS) oligodeoxynucleotides directed against the first six codons of the human serglycin proteoglycan gene. As controls, PDE scrambled and PS sense and scrambled sequences and a probe antisense to a 3' portion of the coding sequence were used. Treatment with PDE-ODNs did not alter the core protein content of cell or culture medium proteoglycans. Treatment with all the PS-ODNs resulted in loss of the 31 kD serglycin core protein in the medium, but not the cell-associated proteoglycans, and concomitant appearance of a heavily labeled core protein band at the dye front. This band appears to arise from truncation of the core protein, which leaves the glycosaminoglycan attachment region intact. The higher molecular weight core proteins, which appear to be derived from a betaglycan-like proteoglycan, were not affected by the PDE or PS-ODN treatment. The same effect was seen with or without electroporation, which was used to enhance uptake of the ODNs. Thus treatment of megakaryocytic tumor cells with PS-ODNs appeared to cause a selective degradation of the serglycin core protein in a sequence-independent manner. Degradation most likely occurred intracellularly, because culture supernatants did not degrade exogenously added serglycin proteoglycan, and the presence of superoxide dismutase and catalase in the culture medium during exposure of the cells to the PS-ODNs did not prevent the degradation.

Cloning and expression of a cDNA for the human prostacyclin receptor

A functional cDNA for the human prostacyclin receptor was isolated from a cDNA library of CMK cells, a human megakaryocytic leukaemia cell line. The cDNA encodes a protein consisting of 386 amino acid residues with seven putative transmembrane domains and a deduced molecular weight of 40,956. [3H]Iloprost specifically bound to the membrane of CHO cells stably expressing the cDNA with a Kd of 3.3 nM. This binding was displaced by unlabelled prostanoids in the order of iloprost = cicaprost >> carbacyclin > prostaglandin E1 (PGE1) > STA2. PGE2, PGD2 and PGF 2 alpha did not inhibit it. Iloprost in a concentration-dependent manner increased the cAMP level and generated inositol trisphosphate in these cells, indicating that this human receptor can couple to multiple signal transduction pathways.

Phorbol ester treatment of two megakaryoblastic cell lines, CMK and UT-7, induces specific protein composition changes with non-coincident time-courses

The expressions of platelet-specific glycoprotein(GP)s Ib, IIb and IIIa were analyzed in 2 megakaryoblastic cell lines: CMK and UT-7. Phorbol-12 myristate 13-acetate (PMA) treatment of CMK induced expressions of GPs IIb and IIIa that peaked on the 4th day post-treatment, while treated UT-7 cells showed maximal levels of these GPs during the 6-8th days. Antibody staining to detect the formation of GPIb alpha after PMA induction showed the presence of the intact GP in UT-7 and the degraded form in CMK. In UT-7, synthesis of GPIIb mRNA increased on days 4-6 after PMA treatment, in parallel with the increase of GPIIb. PMA increased the cytoskeletal protein (actin and myosin) contents in both lines, but in contrast to the two GPs, the increase in these proteins started immediately after PMA addition to the cells. Cell surface proteins of CMK and UT-7 cells were rapidly modified after PMA induction. Especially notable were the degradations of 93-kDa and 140-kDa proteins that occurred on days 1-2 after PMA treatment. These studies demonstrate that the expression of platelet-specific proteins shows a different time dependency than the increment of cytoskeletal proteins, indicating that the syntheses of these two classes of proteins are most likely induced through different mechanisms.

Elevation of intracellular calcium ion by prostaglandin E1 and its inhibition by protein kinase C in a human megakaryocyte leukemia cell line

In the present study, we examined the effect of prostaglandin E1 (PGE1) on Ca2+ mobilization in a human megakaryocyte (the progenitor of platelets) leukemia cell line, designated as CMK. PGE1 caused a rapid and dose-dependent increase in the intracellular free calcium level ([Ca2+]i) associated with the elevation of cyclic AMP. The PGE1-induced elevation of [Ca2+]i was decreased by the prior addition of ethylene glycol bis(2-aminoethylether)tetraacetic acid to the medium by approximately 25% of the control. This result indicates that the PGE1-induced elevation of [Ca2+]i is due to influx of Ca2+ from the external medium and to mobilization of Ca2+ from intracellular stores. Pretreatment of CMK cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), a stimulus for protein kinase C, further enhanced the PGE1-induced increase in the cellular cyclic AMP level. Inversely, pretreatment of CMK cells with TPA (10 nM), prior to the addition of PGE1, inhibited the PGE1-induced elevation of [Ca2+]i. Dibutyryl cyclic AMP and forskolin did not elevate [Ca2+]i or affect the PGE1-induced Ca2+ mobilization. The inhibitory action of TPA in the PGE1-induced elevation of [Ca2+]i was mimicked by other protein kinase C-activating agents, such as 1-oleoyl-2-acetylglycerol and N-(6-phenylhexyl)-5-chloro-1-naphthalenesulfonamide, and was selectively restored by protein kinase C inhibitors, such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride and N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride. Thus, the inhibitory modulation of TPA on the PGE1-induced elevation of [Ca2+]i is mediated through protein kinase C activation. PGE1 had no inductional effect of megakaryocytic phenotypic changes in CMK cells. The biological role of PGE1, which increased [Ca2+]i and cyclic AMP levels in the CMK cells, remains to be determined.