Cardiovascular events and intensity of treatment in polycythemia vera

Cefazolin-Induced Thrombocytopenia in a Patient with Polycythemia Vera Following Coronary Artery Bypass

Cefazolin is an antibiotic that is commonly administered perioperatively to reduce the risk of surgical site infections. Cephalosporins have a well-established safety profile, but have been associated with thrombocytopenia and neutropenia due to their myelosuppressive effects. While this effect may be benign in healthy patients undergoing minor surgery, it can be detrimental in patients with underlying hematologic disorders presenting for open-heart surgery. Herein, we discuss the first case in the literature of cefazolin-induced thrombocytopenia and severe coagulopathy in a patient with polycythemia vera (PCV) during a coronary artery bypass-grafting surgery.

MDM2 antagonist idasanutlin in patients with polycythemia vera: results from a single-arm phase 2 study

Idasanutlin showed clinical activity in patients with HU-resistant/-intolerant PV, but chronic toxicity led to a high discontinuation rate.

Significant reductions in JAK2 allele burden occurred after 3 treatment cycles and were greatest in patients with clinical response.

Idasanutlin, an MDM2 antagonist, showed clinical activity and a rapid reduction in JAK2 V617F allele burden in patients with polycythemia vera (PV) in a phase 1 study. This open-label phase 2 study evaluated idasanutlin in patients with hydroxyurea (HU)-resistant/-intolerant PV, per the European LeukemiaNet criteria, and phlebotomy dependence; prior ruxolitinib exposure was permitted. Idasanutlin was administered once daily on days 1 through 5 of each 28-day cycle. The primary end point was composite response (hematocrit control and spleen volume reduction > 35%) in patients with splenomegaly and hematocrit control in patients without splenomegaly at week 32. Key secondary end points included safety, complete hematologic response (CHR), patient-reported outcomes, and molecular responses. All patients (n = 27) received idasanutlin; 16 had response assessment (week 32). Among responders with baseline splenomegaly (n = 13), 9 (69%) attained any spleen volume reduction, and 1 achieved composite response. Nine patients (56%) achieved hematocrit control, and 8 patients (50%) achieved CHR. Overall, 43% of evaluable patients (6/14) showed a ≥50% reduction in the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (week 32). Nausea (93%), diarrhea (78%), and vomiting (41%) were the most common adverse events, with grade ≥ 3 nausea or vomiting experienced by 3 patients (11%) and 1 patient (4%), respectively. Reduced JAK2 V617F allele burden occurred early (after 3 cycles), with a median reduction of 76%, and was associated with achieving CHR and hematocrit control. Overall, the idasanutlin dosing regimen showed clinical activity and rapidly reduced JAK2 allele burden in patients with HU-resistant/- intolerant PV but was associated with low-grade gastrointestinal toxicity, leading to poor long-term tolerability. This trial was registered at www.clinincaltrials.gov as #NCT03287245.

Tmprss6-ASO as a tool for the treatment of Polycythemia Vera mice

Polycythemia Vera (PV) is a chronic myeloproliferative neoplasm resulting from an acquired driver mutation in the JAK2 gene of hematopoietic stem and progenitor cells resulting in the overproduction of mature erythrocytes and abnormally high hematocrit, in turn leading to thromboembolic complications. Therapeutic phlebotomy is the most common treatment to reduce the hematocrit levels and consequently decrease thromboembolic risk. Here we demonstrate that, by using the iron restrictive properties of the antisense oligonucleotides against Tmprss6 mRNA, we can increase hepcidin to achieve effects equivalent to therapeutic phlebotomy. We provide evidence that this less invasive approach could represent an additional therapeutic tool for the treatment of PV patients.

JAK2V617F variant allele frequency >50% identifies patients with polycythemia vera at high risk for venous thrombosis

Arterial (AT) and venous (VT) thrombotic events are the most common complications in patients with polycythemia vera (PV) and are the leading causes of morbidity and mortality. In this regard, the impact of JAK2V617F variant allele frequency (VAF) is still debated. The purpose of the current study was to analyze the impact of JAK2V617F VAF in the context of other established risk factors for thrombosis in a total of 865 2016 WHO-defined PV patients utilizing two independent cohorts: University of Florence (n = 576) as a training cohort and Policlinico Gemelli, Catholic University, Rome (n = 289) as a validation cohort. In the training cohort VT free-survival was significantly shorter in the presence of a JAK2V617F VAF > 50% (HR 4; p < 0.0001), whereas no difference was found for AT (HR 0.9; p = 0.8). Multivariable analysis identified JAK2V617F VAF > 50% (HR 3.8, p = 0.001) and previous VT (HR 2.2; p = 0.04) as independent risk factors for future VT whereas diabetes (HR 2.4; p = 0.02), hyperlipidemia (HR 2.3; p = 0.01) and previous AT (HR 2; p = 0.04) were independent risk factors for future AT. Similarly, JAK2V617F VAF > 50% (HR 2.4; p = 0.01) and previous VT (HR 2.8; p = 0.005) were confirmed as independent predictors of future VT in the validation cohort. Impact of JAK2V617F VAF > 50% on VT was particularly significant in conventional low-risk patients, both in Florence (HR 10.6, p = 0.005) and Rome cohort (HR 4; p = 0.02). In conclusion, we identified JAK2V617F VAF > 50% as an independent strong predictor of VT, supporting that AT and VT are different entities which might require distinct management.

Running interferon interference in treating PV/ET: meeting unmet needs

Enthusiasm about interferons for the treatment of myeloproliferative neoplasms has recently arisen. How does a nontargeted therapy selectively target the malignant clone? Many foundational questions about interferon treatment are unanswered, including who, when, and for how long do we treat. Using an individual case, this review touches on gaps in risk assessment in polycythemia vera (PV) and essential thrombocythemia (ET) and the history of treatment with interferons. How is it that this proinflammatory cytokine effectively treats ET and PV, themselves proinflammatory states? We summarize existing mechanistic and clinical data, the molecular context as a modifier for treatment response, the establishment of treatment goals, and the challenges that lie ahead.

MPN and thrombosis was hard enough . . . now there's COVID-19 thrombosis too

Both myeloproliferative neoplasms (MPNs) and coronavirus disease 2019 (COVID-19) are characterized by an intrinsic thrombotic risk. Little is known about the incidence and the outcome of thrombotic events in patients with MPN infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but common mechanisms of coagulation activation, typical of both disorders, suggest that these patients can be at particularly high risk. To define the best thromboprophylaxis and treatment regimens in both MPN and COVID-19, individual- and disease-specific thrombotic risk factors, bleeding risk, and concomitant specific treatments need to be considered. In this case-based review, an individualized approach is presented in a case of SARS-CoV-2 infection occurring in a man with polycythemia vera (PV). A primary anticoagulant thromboprophylaxis strategy and adjustment of his PV treatment were implemented. However, during the hospital stay, he experienced pulmonary embolism and therapeutic anticoagulation had to be set. Then his condition improved, and discharge was planned. Postdischarge decisions had to be made about the type and duration of venous thromboembolism treatment as well as the management of PV-specific drugs. The steps of our decisions and recommendations are presented.

Polycythemia vera: historical oversights, diagnostic details, and therapeutic views

Polycythemia vera (PV) is a relatively indolent myeloid neoplasm with median survival that exceeds 35 years in young patients, but its natural history might be interrupted by thrombotic, fibrotic, or leukemic events, with respective 20-year rates of 26%, 16%, and 4%. Current treatment strategies in PV have not been shown to prolong survival or lessen the risk of leukemic or fibrotic progression and instead are directed at preventing thrombotic complications. In the latter regard, two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). All patients require phlebotomy to keep hematocrit below 45% and once-daily low-dose aspirin, in the absence of contraindications. Cytoreductive therapy is recommended for high-risk or symptomatic low-risk disease; our first-line drug of choice in this regard is hydroxyurea but we consider pegylated interferon as an alternative in certain situations, including in young women of reproductive age, in patients manifesting intolerance or resistance to hydroxyurea therapy, and in situations where treatment is indicated for curbing phlebotomy requirement rather than preventing thrombosis. Additional treatment options include busulfan and ruxolitinib; the former is preferred in older patients and the latter in the presence of symptoms reminiscent of post-PV myelofibrosis or protracted pruritus. Our drug choices reflect our appreciation for long-term track record of safety, evidence for reduction of thrombosis risk, and broader suppression of myeloproliferation. Controlled studies are needed to clarify the added value of twice- vs once-daily aspirin dosing and direct oral anticoagulants. In this invited review, we discuss our current approach to diagnosis, prognostication, and treatment of PV in general, as well as during specific situations, including pregnancy and splanchnic vein thrombosis.

Prevention of venous thromboembolism in hematologic neoplasms: an expert consensus from SEHH-SETH

Venous thromboembolism (VTE) is a serious complication in hematologic neoplasms, so finding adequate prevention strategies is an urgent requirement. However, prospective studies with large enough cohorts are scarce, limiting the development of evidence-based thromboprophylaxis guidelines. The present position paper is addressed to all hematologists treating patients affected by hematologic neoplasms with the aim to provide clinicians with a useful tool for the prevention of VTE.

Cytoreductive treatment in real life: a chart review analysis on 1440 patients with polycythemia vera

Purpose

Patients with polycythemia vera (PV) show an elevated incidence of thromboembolic complications and decreased survival when compared to age-matched healthy individuals. Hypercellularity as indicated by elevated hematocrit, pathophysiological changes induced by the JAK2 driver mutation and cardiovascular risk factors contribute to the increased incidence of thromboembolic events. Higher age and a history of thromboembolic events define a high-risk population of PV patients. Depending on the individual risk profile, phlebotomy or pharmacologic cytoreduction is recommended in combination with low-dose acetylsalicylic acid. Stringent cytoreduction is required for effective risk reduction. However, in recent reports, the rate of thromboembolic complications in PV patients under cytoreductive therapy appears still elevated compared to healthy individuals. This study reports on a chart review to assess for cytoreductive therapy of 1440 PV patients in real life.

Methods

Forty-two eligible hematologists/oncologists in private practice treating patients with MPN were recruited to participate in a paper–pencil-based survey conducted between January 2019 and March 2020 in Germany. Physicians were asked to report primary documented data obtained from patient charts. Descriptive analyses were conducted to assess for patient characteristics, treatment modalities, risk factors and thromboembolic complications.

Results

Data were collected from the patient charts of 1440 individuals diagnosed with PV. The patient population was older than those reported in multicenter trials with a median age of 72.2 years at the time of reporting and 63.5 years at diagnosis. Age was the main factor accounting for high-risk status with 84.7% of patients being above the age of 60 followed by thromboembolic complications reported in 21.3% of patients. The use of pharmacologic cytoreduction was highly variable between participating centers with an average of 60.7% and a range of 10.1–100%. Hydroxyurea was the most frequently used drug followed by ruxolitinib, while interferons were reported for a minority of patients. For 35.4% of patients a persistent need for phlebotomy in addition to cytoreductive treatment was reported. Although presence of high-risk criteria and insufficient disease control were reported as main triggers to initiate pharmacologic cytoreduction, 28.1% had elevated hematocrit values (> 45%) and 38.6% showed persistence of elevated leukocyte count (> 10^9/l) while on cytoreductive treatment. In contrast, physician-reported symptom burden was lower than published in clinical trials and patient-reported outcomes. The rate of patients experiencing thromboembolic complications was 32.2% at any time and 14.3% after diagnosis with most patients receiving acetylsalicylic acid and 10.8% remaining on oral anticoagulants or heparin.

Conclusions

Cytoreductive treatment of high-risk PV in real life is highly variable regarding indication for cytoreduction and definition of therapy resistance. This study highlights the need for (i) improved risk stratification for thromboembolic events, (ii) consequent indication of pharmacologic cytoreduction in high-risk PV and (iii) attention to signs of therapy resistance that can trigger an earlier and stringent switch to second line agents.

The Association Between Parameters of Erythrocytes Morphology and Thrombophilia-Related Mutations

BACKGROUND

Alterations in erythrocyte morphology parameters have been identified and associated with hematological disorders and other chronic and cardiovascular diseases. Erythrocytes are abundant in thrombus content. Their hemoglobin density and differences in the ratio of macrocytic and microcytic cells may be associated with hypercoagulopathy in those with a history of thrombosis.

OBJECTIVE

This cross-sectional study aimed to investigate the relationship between hemogram parameters and thrombophilia genetic parameters.

METHOD

A total of 55 patients whose thrombophilia panel was reviewed due to the diagnosis of thrombosis were included in the study. %MIC, %MAC, %HPO, %HPR and all hemogram parameters were measured using Abbott Alinity HQ. Prothrombin G20210A, MTHFR C677T, MTHFR A1298C, Factor V Leiden G169A and PAI-1 4G/5G mutations were studied using Real Time-PCR.

RESULTS

The MTHFR C677T mutation was detected in 58.2% of the patients. The Factor V Leiden mutation was detected in 5.5% of the patients. The MTHFR A1298C mutation was detected in 58.2%, The PAI mutation was detected in 74.5%, and the Factor 13 mutation was detected in 29% of the patients. Prothrombin G20210A mutation was not detected in any of the patients. Red blood cell (RBC) and Hct values were higher in Factor 13 mutant group; the Hgb and Htc values were higher in the MTHFR C677T mutant group.

CONCLUSION

The MTHFR C677T and Factor 13 mutations may be associated with high Hct and RBC, Hgb, and Htc values, respectively and coagulation tendency in patients with a history of thrombosis.

Polycythaemia Vera and Coronary Artery Bypass Graft Surgery: A Systematic Review of the Literature

OBJECTIVES

Polycythaemia vera (PV) is a condition that may potentially put patients undergoing cardiac surgery at an increased risk of bleeding and thrombosis; however, there is currently a paucity of literature regarding the management of these patients. We aim to examine the literature in this systematic review to indicate the interventions that may be considered to minimise complications.

METHODS

We conducted a literature search using keywords and MeSH terms to identify articles discussing PV and cardiac surgery. The studies were identified and qualitatively analysed using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol.

RESULTS

In total, 10 case reports representing 11 patients were identified for this systematic review and were included in qualitative analysis. 63.6% of patients had preoperative intermittent phlebotomy, and the majority of patients received postoperative therapy that involved one antiplatelet and one anticoagulant. Generous perioperative fluid management, phlebotomy, preservation of core body temperature, early extubation, monitoring of myocardial ischaemia, infarction and vascular events, intense chest physiotherapy and patient mobilisation are important to consider to reduce the risk of complications arising from surgery.

CONCLUSION

These considerations should be systematically discussed in a multidisciplinary team, where the acute surgical need can be balanced appropriately against the risk of haemorrhage and thrombosis.

Heart failure with reduced ejection fraction due topolycythemia vera

Polycythemia vera is a rare hematological disorder that can cause heart failure with reduced ejection fraction from chronic micro-vascular ischemia. Appropriately recognizing the underlying cause of cardiomyopathy is essential to decrease morbidity and mortality. Patients can present with elevated troponin level and have patent epicardial coronary arteries on coronary angiogram, hence presenting a diagnostic challenge for health care professionals. Furthermore, the presentation can mimic myocarditis. Herein, we report a case of a 61-year-old female who presented with heart failure due to microvascular thrombotic complication associated with polycythemia vera. Laboratory investigation and coronary angiogram were inconclusive. A high degree of clinical suspicion and utilizing non-invasive techniques, such as cardiac imaging, can describe myocardial pathology and aid with the diagnosis.

Hematocrit to hemoglobin ratio as a prognostic marker in polycythemia vera

BACKGROUND

The hematocrit to hemoglobin ratio (HHR) is frequently used in everyday practice to measure hemoconcentration; however, clinical associations of HHR in the context of polycythemia vera (PV) have not been investigated so far.

PATIENTS AND METHODS

We retrospectively assessed HHR at the time of diagnosis in 107 PV and 40 secondary polycythemia (SP) patients from three community hospitals.

RESULTS

Median HHR was higher in PV than in SP patients (3.131 vs. 2.975, p = 0.041). Among PV patients, higher HHR correlated with splenomegaly, higher total leukocyte and absolute granulocyte counts, higher red blood cell counts, lower hemoglobin, higher red blood cell distribution width, lower mean corpuscular hemoglobin and lower ferritin levels, whereas in SP patients higher HHR correlated with older age, female sex and lower hemoglobin (p < 0.050 for all analyses). Using the receiver operating curve analysis-defined cut-off points, higher HHR in PV was associated with a shorter time to thrombosis (hazard ratio-HR 5.20, p = 0.022) independently of high-risk disease status (HR 4.48, p = 0.034) and shorter overall survival (HR 6.69, p = 0.009) independently of leukocytosis (HR 4.48, P = 0.034) and the absence of aspirin use (HR 15.53, p < 0.001).

CONCLUSION

Higher HHR may represent iron deficiency and a stronger clonal myeloproliferation in PV and could provide additional prognostic information to the classical risk assessment.

Platelet Heterogeneity in Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are a group of malignant disorders of the bone marrow where a dysregulated balance between proliferation and differentiation gives rise to abnormal numbers of mature blood cells. MPNs encompass a spectrum of disease entities with progressively more severe clinical features, including complications with thrombosis and hemostasis and an increased propensity for transformation to acute myeloid leukemia. There is an unmet clinical need for markers of disease progression. Our understanding of the precise mechanisms that influence pathogenesis and disease progression has been limited by access to disease-specific cells as biosources. Here, we review the landscape of MPN pathology and present blood platelets as potential candidates for disease-specific understanding. We conclude with our recent work discovering progressive platelet heterogeneity by subtype in a large clinical cohort of patients with MPN.

Circulating Protein Disulfide Isomerase Is Associated with Increased Risk of Thrombosis in JAK2-Mutated Myeloproliferative Neoplasms

PURPOSE

Thromboembolic events (TE) are the most common complications of myeloproliferative neoplasms (MPN). Clinical parameters, including patient age and mutation status, are used to risk-stratify patients with MPN, but a true biomarker of TE risk is lacking. Protein disulfide isomerase (PDI), an endoplasmic reticulum protein vital for protein folding, also possesses essential extracellular functions, including regulation of thrombus formation. Pharmacologic PDI inhibition prevents thrombus formation, but whether pathologic increases in PDI increase TE risk remains unknown.

EXPERIMENTAL DESIGN

We evaluated the association of plasma PDI levels and risk of TE in a cohort of patients with MPN with established diagnosis of polycythemia vera (PV) or essential thrombocythemia (ET), compared with healthy controls. Plasma PDI was measured at enrollment and subjects followed prospectively for development of TE.

RESULTS

A subset of patients, primarily those with JAK2-mutated MPN, had significantly elevated plasma PDI levels as compared with controls. Plasma PDI was functionally active. There was no association between PDI levels and clinical parameters typically used to risk-stratify patients with MPN. The risk of TE was 8-fold greater in those with PDI levels above 2.5 ng/mL. Circulating endothelial cells from JAK2-mutated MPN patients, but not platelets, demonstrated augmented PDI release, suggesting endothelial activation as a source of increased plasma PDI in MPN.

CONCLUSIONS

The observed association between plasma PDI levels and increased risk of TE in patients with JAK2-mutated MPN has both prognostic and therapeutic implications.

Recent Advances in Molecular Diagnostics and Targeted Therapy of Myeloproliferative Neoplasms

Simple Summary

Myeloproliferative neoplasms (MPN) are clonal hematologic malignancies with dysregulated myeloid blood cell production driven by JAK2, calreticulin, and MPL gene mutations. Technological advances have revealed a heterogeneous genomic landscape with additional mutations mainly in epigenetic regulators and splicing factors, which are of diagnostic and prognostic value and may inform treatment decisions. Thus, genetic testing has become an integral part of the state-of-the-art work-up for MPN. The finding that JAK2, CALR, and MPL mutations activate JAK2 signaling has promoted the development of targeted JAK2 inhibitor therapies. However, their disease-modifying potential remains limited and investigations of additional molecular vulnerabilities in MPN are imperative to advance the development of new therapeutic options. Here, we summarize the current insights into the genetic basis of MPN, its use as diagnostic and prognostic tool in clinical settings, and recent advances in targeted therapies for MPN.

Abstract

Somatic mutations in JAK2, calreticulin, and MPL genes drive myeloproliferative neoplasms (MPN), and recent technological advances have revealed a heterogeneous genomic landscape with additional mutations in MPN. These mainly affect genes involved in epigenetic regulation and splicing and are of diagnostic and prognostic value, predicting the risk of progression and informing decisions on therapeutic management. Thus, genetic testing has become an integral part of the current state-of-the-art laboratory work-up for MPN patients and has been implemented in current guidelines for disease classification, tools for prognostic risk assessment, and recommendations for therapy. The finding that JAK2, CALR, and MPL driver mutations activate JAK2 signaling has provided a rational basis for the development of targeted JAK2 inhibitor therapies and has fueled their translation into clinical practice. However, the disease-modifying potential of JAK2 inhibitors remains limited and is further impeded by loss of therapeutic responses in a substantial proportion of patients over time. Therefore, the investigation of additional molecular vulnerabilities involved in MPN pathogenesis is imperative to advance the development of new therapeutic options. Combination of novel compounds with JAK2 inhibitors are of specific interest to enhance therapeutic efficacy of molecularly targeted treatment approaches. Here, we summarize the current insights into the genetic basis of MPN, its use as a diagnostic and prognostic tool in clinical settings, and the most recent advances in targeted therapies for MPN.

Philadelphia-Negative Myeloproliferative Neoplasms Around the COVID-19 Pandemic

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is associated with a high rate of respiratory failure, thromboembolism, bleeding, and death. Patients with myeloproliferative neoplasms (MPNs) are prone to both thrombosis and bleeding, calling for special care during COVID-19. We reviewed the clinical features of MPN patients with COVID-19, suggesting guidance for treatment.

RECENT FINDINGS

One study by the European LeukemiaNet collected 175 MPN patients with COVID-19 during the first wave of the pandemic, from February to May 2020. Patients with primary myelofibrosis (PMF) were at higher risk of mortality (48%) in comparison with essential thrombocythemia (ET) (25%) and polycythemia vera (19%); the risk of death was higher in those patients who abruptly discontinued ruxolitinib. In patients followed at home, in regular wards, or in ICU, the thrombosis rate was 1.0%, 2.8%, and 18.4%, respectively. Independent risk factors for thrombosis were ET phenotype, transfer to ICU, and neutrophil/lymphocyte ratio; major bleeding occurred in 4.3% of patients, particularly those with PMF. MPN patients with non-severe COVID-19 treated at home should continue their primary or secondary antithrombotic prophylaxis with aspirin or oral anticoagulants. In the case of hospitalization, patients assuming aspirin should add low molecular weight heparin (LMWH) at standard doses. In contrast, LMWH at intermediate/therapeutic doses should replace oral anticoagulants prescribed for atrial fibrillation or previous venous thromboembolism. Intermediate/high doses of LMWH can also be considered in ICU patients with ET, particularly in the case of a rapid decline in the number of platelets and progressive respiratory failure.

Lemierre's Syndrome in an Elderly Female Patient with Polycythemia Vera: Does Polycythemia Vera Predispose to Lemierre's Syndrome?

Patient: Female, 66-year-old

Final Diagnosis: Lemierre’s syndrome

Symptoms: Chills • neck pain • odynophagia • rigors • trismus

Medication: —

Clinical Procedure: Computed tomography

Specialty: Cardiology • Hematology • Infectious Diseases • General and Internal Medicine

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs): A continuum of different disease entities

Classical Philadelphia-negative myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell-derived disorders characterized by uncontrolled proliferation of differentiated myeloid cells and close pathobiologic and clinical features. According to the 2016 World Health Organization (WHO) classification, MPNs include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision aimed in particular at strengthening the distinction between masked PV and JAK2-mutated ET, and between prefibrotic/early (pre-PMF) and overt PMF. Clinical manifestations in MPNs include constitutional symptoms, microvascular disorders, thrombosis and bleeding, splenomegaly secondary to extramedullary hematopoiesis, cytopenia-related symptoms, and progression to overt MF and acute leukemia. A dysregulation of the JAK/STAT pathway is the unifying mechanistic hallmark of MPNs, and is guided by somatic mutations in driver genes including JAK2, CALR and MPL. Additional mutations in myeloid neoplasm-associated genes have been also identified, with established prognostic relevance, particularly in PMF. Prognostication of MPN patients relies on disease-specific clinical models. The increasing knowledge of MPN biology led to the development of integrated clinical and molecular prognostic scores that allow a more refined stratification. Recently, the therapeutic landscape of MPNs has been revolutionized by the introduction of potent, selective JAK inhibitors (ruxolitinib, fedratinib), that proved effective in controlling disease-related symptoms and splenomegaly, yet leaving unmet critical needs, owing the lack of disease-modifying activity. In this review, we will deal with molecular, clinical, and therapeutic aspects of the three classical MPNs aiming at highlighting either shared characteristics, that overall define a continuum within a single disease family, and uniqueness, at the same time.

Philadelphia-Negative Chronic Myeloproliferative Neoplasms during the COVID-19 Pandemic: Challenges and Future Scenarios

An outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) started in December 2019 in China and then become pandemic in February 2020. Several publications investigated the possible increased rate of COVID-19 infection in hematological malignancies. Based on the published data, strategies for the management of chronic Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) are provided. The risk of severe COVID-19 seems high in MPN, particularly in patients with essential thrombocythemia, but not negligible in myelofibrosis. MPN patients are at high risk of both thrombotic and hemorrhagic complications and this must be accounted in the case of COVID-19 deciding on a case-by-case basis. There are currently no data to suggest that hydroxyurea or interferon may influence the risk or severity of COVID-19 infection. Conversely, while the immunosuppressive activity of ruxolitinib might pose increased risk of infection, its abrupt discontinuation during COVID-19 syndrome is associated with worse outcome. All MPN patients should receive vaccine against COVID-19; reassuring data are available on efficacy of mRNA vaccines in MPNs.

Head and Neck Reconstruction in Patients with Polycythemia Vera: Case Series and Literature Review

Background  Polycythemia vera (PV) is a myeloproliferative disease with overproduction of erythrocytes, leukocytes, and platelets causing an increased risk of both thrombosis and hemorrhage. There are limited reports and no established guidelines for managing such patients undergoing reconstructive surgery. Methods  We present four patients with PV and head and neck cancer who required reconstruction after resection and provide a review of the current literature. Results  Preoperatively, patients on cytoreductive therapy continued with their treatment throughout their hospital course and had hematologic parameters normalized with phlebotomy or transfusions if needed. Two patients who underwent free flap surgery (cases 1 and 2) had postoperative courses complicated by hematoma formation and persistent anemia, requiring multiple transfusions. Cases 3 and 4 (JAK2+ PV and JAK2- PV, respectively) underwent locoregional flap without postoperative complications. Conclusion  Concomitant presentation of PV and head and neck cancer is uncommon and presents unique challenges for the reconstructive surgeon. Overall, we recommend that patients should have hematologic parameters optimized prior to surgery, continue ruxolitinib or hydroxyurea, and hold antiplatelet/anticoagulation per established department protocols. It is essential to engage a multidisciplinary team involving hematology, head and neck and reconstructive surgery, anesthesia, and critical care to develop a standardized approach for managing this unique subset of patients.

Telomere Attrition and Clonal Hematopoiesis of Indeterminate Potential in Cardiovascular Disease

Clinical evidence suggests that conventional cardiovascular disease (CVD) risk factors cannot explain all CVD incidences. Recent studies have shown that telomere attrition, clonal hematopoiesis of indeterminate potential (CHIP), and atherosclerosis (telomere-CHIP-atherosclerosis, TCA) evolve to play a crucial role in CVD. Telomere dynamics and telomerase have an important relationship with age-related CVD. Telomere attrition is associated with CHIP. CHIP is commonly observed in elderly patients. It is characterized by an increase in blood cell clones with somatic mutations, resulting in an increased risk of hematological cancer and atherosclerotic CVD. The most common gene mutations are DNA methyltransferase 3 alpha (DNMT3A), Tet methylcytosine dioxygenase 2 (TET2), and additional sex combs-like 1 (ASXL1). Telomeres, CHIP, and atherosclerosis increase chronic inflammation and proinflammatory cytokine expression. Currently, their epidemiology and detailed mechanisms related to the TCA axis remain incompletely understood. In this article, we reviewed recent research results regarding the development of telomeres and CHIP and their relationship with atherosclerotic CVD.

Ischemic stroke as a presenting manifestation of polycythemia vera: a narrative review

Polycythemia vera (PV) is a myeloproliferative disorder associated with an increased risk of cerebrovascular diseases. In this narrative review, we aimed to analyze the relationships between acute ischemic stroke and PV. We conducted a PubMed/Medline and Web of Sciences Database search using MeSH major terms. We found 75 articles and finally considered 12 case reports and 11 cohort studies. The ischemic stroke resulted as the first manifestation of PV in up to 16.2% of cases; the cumulative rate of cerebrovascular events was up to 5.5 per 100 persons per year and stroke accounted for 8.8% of all PV-related deaths; age, mutations, and a previous history of thrombosis were the main risk factors. The best approach to reduce stroke recurrence risk is unclear, even if some evidence suggests a potential role of lowering hematocrit below 45%. Ischemic stroke represents one of the most common PV manifestations but, despite their relationship, patients with both diseases have a very heterogeneous clinical course and management. PV-related strokes often remain underdiagnosed, especially for the low prevalence of PV. An early diagnosis could lead to prompt treatment with phlebotomy, cytoreduction, and low-dose aspirin to decrease the risk of recurrences. Clinicians should be aware of PV as a risk factor for stroke when approaching the differential diagnosis of cryptogenic strokes. An early diagnosis could positively influence patients' management and clinical outcomes. Further studies are required to evaluate the role of PV treatments in the prevention of cerebrovascular disease.

Hemorrhagic transformation after acute ischemic stroke caused by polycythemia vera: Report of two case

BACKGROUND

Polycythemia vera (PV) is a chronic myeloproliferative disorder characterized by an increase in red blood cells in the peripheral blood. Previous work has reported the occurrence of thrombosis or hemorrhage arising in the cerebral vasculature secondary to PV. However, hemorrhagic transformation after PV-associated acute ischemic stroke has not been previously described.

CASE SUMMARY

We herein present two cases of PV where hemorrhagic transformation occurred after an acute ischemic stroke. Case 1 was a 57-year-old woman with a history of hypertension who was admitted for left-sided weakness. Case 2 was a 68-year-old man who was admitted for a 10-d sudden left arm weakness. Imaging examinations for the two patients revealed hemorrhagic transformation after acute ischemic stroke. Both patients had JAK-2-V617F mutation and received antiplatelet therapy. Both of them had a good prognosis during the follow-up.

CONCLUSION

This report suggested that hemorrhagic transformation may occur in acute ischemic stroke caused by PV. Antiplatelet drugs do not seem to influence the long-term outcomes in such patients. Future research should focus on establishing a standard antiplatelet treatment strategy for this condition.

Management Issues and Controversies in Low-Risk Patients with Essential Thrombocythemia and Polycythemia Vera

PURPOSE OF REVIEW

Essential thrombocythemia (ET) and polycythemia vera (PV) are the most common myeloproliferative neoplasms (MPNs). Treatment of ET and PV is based on the risk for subsequent thrombosis. High-risk patients, defined as older than 60, JAK2 V617F-positive patients, or patients with a history of prior thrombosis, merit cytoreduction to control blood counts, whereas a watchful waiting paradigm is utilized in low-risk patients. However, low-risk patients have a host of other specific management issues that arise during their disease course. This review will discuss the most common management issues specific to the care of low-risk patients, including anti-platelet therapy dosing, pregnancy, and indications for early cytoreduction.

RECENT FINDINGS

Although low-dose aspirin is well established in PV, its indications and dosing regimens are less clear in ET. Recent evidence has supported twice daily low-dose aspirin in ET and observation alone in very low-risk ET patients. Pregnancy is not contraindicated in MPNs, and we recommend aspirin throughout pregnancy with consideration for prophylactic postpartum anticoagulation. High phlebotomy needs, symptom burden, and extreme thrombocytosis are common reasons for initiation of cytoreduction in low-risk patients, although we typically do not start cytoreduction for an isolated high platelet count alone. Recent data has also demonstrated a potential disease-modifying effect of interferons in MPNs, with some experts now advocating the early use of interferon in low-risk patients, although more mature data is needed before practice guidelines change. We evaluate the literature to inform clinical decision-making regarding these controversies, including most recent data that has challenged the "watchful waiting" paradigm. Our discussion provides guidance on common clinical scenarios seen in low-risk ET and PV patients, who face a myriad of complex management decisions in their care.

The Role of Neutrophilic Granulocytes in Philadelphia Chromosome Negative Myeloproliferative Neoplasms

Philadelphia chromosome negative myeloproliferative neoplasms (MPN) are composed of polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF). The clinical picture is determined by constitutional symptoms and complications, including arterial and venous thromboembolic or hemorrhagic events. MPNs are characterized by mutations in JAK2, MPL, or CALR, with additional mutations leading to an expansion of myeloid cell lineages and, in PMF, to marrow fibrosis and cytopenias. Chronic inflammation impacting the initiation and expansion of disease in a major way has been described. Neutrophilic granulocytes play a major role in the pathogenesis of thromboembolic events via the secretion of inflammatory markers, as well as via interaction with thrombocytes and the endothelium. In this review, we discuss the molecular biology underlying myeloproliferative neoplasms and point out the central role of leukocytosis and, specifically, neutrophilic granulocytes in this group of disorders.

NK Cells in Myeloproliferative Neoplasms (MPN)

Simple Summary

NK cells are important innate immune effectors that contribute substantially to tumor control, however the role of NK cells in haematological cancers is not as well understood. The aim of this review is to highlight the importance of the role of NK cells in the management of Ph+ Myeloproliferative Neoplasms, and emphasize the need and possible benefits of a more in-depth investigation into their role in classical MPNs and show potential strategies to harness the anti-tumoral capacities of NK cells.

Abstract

Myeloproliferative neoplasms (MPNs) comprise a heterogenous group of hematologic neoplasms which are divided into Philadelphia positive (Ph+), and Philadelphia negative (Ph−) or classical MPNs. A variety of immunological factors including inflammatory, as well as immunomodulatory processes, closely interact with the disease phenotypes in MPNs. NK cells are important innate immune effectors and substantially contribute to tumor control. Changes to the absolute and proportionate numbers of NK cell, as well as phenotypical and functional alterations are seen in MPNs. In addition to the disease itself, a variety of therapeutic options in MPNs may modify NK cell characteristics. Reports of suppressive effects of MPN treatment strategies on NK cell activity have led to intensive investigations into the respective compounds, to elucidate the possible negative effects of MPN therapy on control of the leukemic clones. We hereby review the available literature on NK cells in Ph+ and Ph− MPNs and summarize today’s knowledge on disease-related alterations in this cell compartment with particular focus on known therapy-associated changes. Furthermore, we critically evaluate conflicting data with possible implications for future projects. We also aim to highlight the relevance of full NK cell functionality for disease control in MPNs and the importance of considering specific changes related to therapy in order to avoid suppressive effects on immune surveillance.

Subdural Hemorrhage Due to Acquired Von Willebrand Syndrome in a Patient With Polycythemia Vera

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm associated with thrombosis. A 48-year-old female with PV presented with right eye pain following a low-impact head trauma. She consumed aspirin for analgesia and took preparations of Chinese herbs. CT head revealed right-sided subdural hematoma. She had reduced Von Willebrand activity to 26%. Direct angiographic imaging showed an aneurysm arising from a right middle cerebral atery (MCA) branch. The patient was given 1-deamino-8-D-arginine vasopressin (DDAVP) prior to the craniotomy. Intra-operative examination revealed that the aneurysm-like structure was a small grape-like structure of the fibrinous part of the subdural membrane that had formed from the subdural hematoma. Acquired von Willebrand syndrome (AVWS) is an important risk factor for bleeding in PV. DDAVP may be useful to increase levels of Von Willebrand Factor (VWF) and decrease the risk of bleeding perioperatively. Exogenous substances such as ginseng should be investigated as possible contributors to bleeding tendency and discontinued.

Clinical Characteristics of Pediatric Patients with Congenital Erythrocytosis: A Single-Center Study

Although congenital erythrocytosis (CE), an inherited disorder, impairs pediatric quality of life, physicians often overlook high hemoglobin (Hgb) levels and its symptoms due to lack of knowledge of age-adjusted pediatric Hgb levels and CE's rarity. In a retrospective, single-center study, data from hospital records of pediatric patients diagnosed with CE were evaluated. Twenty-six patients from 25 families (80.8% male) had been diagnosed with CE in 20 years, at a mean age of 14.9 ± 2.8 years (8.3-17.8) and with a mean Hgb level of 17.36 ± 1.44 g/dL (14.63-22.1). No serum erythropoietin levels exceeded the reference levels. Although the most common symptom was headache (85%), 38% of patients presented with at least one gastrointestinal symptom (e.g., nausea, vomiting, abdominal pain, and rectal bleeding), and 54% exhibited plethora. No patient had leukocytosis, thrombocytosis, JAK2 mutation; capillary oxygen saturation, venous blood gas analysis, and Hgb electrophoresis revealed no abnormalities. While 34.6% of patients had family histories of CE, 42.3% had 15-45-year-old relatives who had experienced myocardial infarction, stroke, and/or sudden death. Aspirin was routinely prescribed, and phlebotomy was performed when hyperviscosity symptoms were present. To detect CE, physicians should consider age-adjusted normal Hgb levels in children. Pediatric patients with CE may also present with gastrointestinal symptoms. Although no thrombotic episode occurred among the patients, their family histories included life-threatening thrombotic episodes, even in adolescents.

Vascular target organ damage in patients with Philadelphia negative myeloproliferative syndrome: A propensity score analysis

PURPOSE

To assess whether subjects with Philadelphia negative myeloproliferative neoplasms (Ph-MPNs) show differences in the presence of vascular, cardiac or renal target organ damage (TOD) and other vascular function parameters as compared to individuals without this condition.

METHODS

An observational study was conducted. Fifty-seven subjects diagnosed with Ph-MPNs used as cases and 114 subjects without Ph-MPNs as controls. We matched the subjects with and without Ph-MPNs using the propensity scores in a 1:2 ratio using the variables gender, type 2 diabetes mellitus, high blood pressure, hyperlipidaemia and smoking. Vascular, cardiac and renal TOD were established according to the criteria of the European Society of Hypertension and Cardiology guidelines. Arterial stiffness was also assessed using the cardio-ankle vascular index (CAVI).

RESULTS

Mean age was 63.50±11.70 and 62.90±8.32 years in subjects with and without Ph-MPNs, 32 females (56%) in the first group and 62 (54%) in the second. Subjects with Ph-MPNs have a higher percentage of carotid injury than subjects without Ph-MPNs (35.1% vs. 21.1%) and higher albumin/creatinine ratio. In the logistic regression analysis, subjects with Ph-MPNs had an OR=2.382 (IC95% 1.066-5.323) for carotid injury versus those without haematological disease.

CONCLUSIONS

Subjects with Ph-MPNs have twice the risk of by carotid injury than those without haematological disease.

Improving the investigative approach to polycythaemia vera: a critical assessment of current evidence and vision for the future

Polycythaemia vera is a challenging disease to study given its low prevalence and prolonged time-to-event for important clinical endpoints such as thrombosis, progression, and mortality. Although researchers in this space often rise to meet these challenges, there is considerable room for improvement in the analysis of retrospective data, the development of risk-stratification tools, and the design of randomised controlled trials. In this Viewpoint, we review the evidence behind the contemporary approach to risk stratification and treatment of polycythaemia vera. Frameworks for using data more efficiently, constructing more nuanced prognostic models, and overcoming challenges in clinical trial design are discussed.

Polycythemia Vera Presenting as Hemorrhagic Stroke

Patients with polycythemia vera are at high risk for vaso-occlusive events including cerebral ischemia and hemorrhage. Cerebral ischemic events are due to increased blood viscosity and platelet activation within the central nervous system arterial vessels. We present a case of a 65-year-old woman who presented to the emergency department with seizures followed by left-sided weakness. Hematologic investigations revealed a hyperviscous state, and magnetic resonance imaging (MRI) was consistent with bilateral hemorrhagic infarction. Genetic studies were positive for polycythemia vera mutation. Symptoms improved with phlebotomy and antiplatelet agents. Through this case, we aim to highlight polycythemia vera as a cause of hemorrhagic stroke and the importance of blood counts in the routine evaluation of the same.

Thrombosis in patients with myeloproliferative neoplasms. Case report

Thrombotic complications are the most significant factors determining the prognosis in myeloproliferative neoplasms. Markers for assessing the risk of thrombosis are the number of leukocytes, platelets, hemoglobin level, hematocrit, age, molecular status, history of thrombosis, obesity, arterial hypertension, hyperlipidemia, hereditary or acquired thrombophilia. The pathogenesis of thrombosis in patients with myeloproliferative neoplasms is complex and multifactorial. In most cases, the etiological factor remains unknown. Currently, antiplatelet and anticoagulant therapy is carried out on an individual basis. The algorithm for primary and secondary (after thrombosis) prevention requires development and testing. We present a clinical case of repeated arterial and venous thrombotic complications in a patient with primary myelofibrosis.

Clinical insights into the origins of thrombosis in myeloproliferative neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), polycythemia vera, essential thrombocythemia, and primary myelofibrosis, are hematopoietic stem cell disorders that are defined by activating mutations in signal transduction pathways and are characterized clinically by the overproduction of platelets, red blood cells, and neutrophils, significant burden of disease-specific symptoms, and high rates of vascular events. The focus of this review is to critically reevaluate the clinical burden of thrombosis in MPNs, to review the clinical associations among clonal hematopoiesis, JAK2V617F burden, inflammation, and thrombosis, and to provide insights into novel primary and secondary thrombosis-prevention strategies.

Clonal Megakaryocyte Dysplasia with Normal Blood Values Is a Distinct Myeloproliferative Neoplasm

INTRODUCTION

In 1991, we reported 18 persons with a clinical-pathologic entity and termed atypical myeloproliferative disorder because they did not meet the contemporary diagnostic criteria for a myeloproliferative neoplasm. We sought to gain further knowledge on this disease entity.

METHODS

This retrospective cohort study included consecutive subjects registered in the database of the Center for the Study of Myelofibrosis in Pavia, Italy, from 1998 to 2020 (June), and diagnosed with atypical myeloproliferative disorder according to our adjudicated criteria. We studied clinical, histological, cytogenetic, and molecular covariates and risks of thrombosis, disease progression, and death. Data were compared with those of concurrent subjects with prefibrotic myelofibrosis.

RESULTS

Fifteen new subjects with atypical myeloproliferative disorder were identified. Seven were male. Median age was 50 years (IQR, 41-54 years). Thirteen were diagnosed with a synchronous symptomatic or incidentally detected thrombotic event. The bone marrow showed megakaryocyte hyperplasia with dysplasia. JAK2V617F was present in 10 subjects and CALR mutation in one. No other somatic mutations were identified in next generation sequencing. After a median follow-up of 101 months (IQR, 40-160 months), no subject had disease progression or blast transformation. Incidence of post-diagnosis or recurrent thrombosis was 3.9 events (95% confidence interval, 3.5-4.0) and 5.0 events (4.6-5.6) per 100 person-years. Features of subjects with atypical myeloproliferative disorder differed markedly from those of 546 subjects with prefibrotic myelofibrosis.

CONCLUSION

Our data indicate that these 15 persons have a distinct myeloproliferative neoplasm. We propose naming this new disorder clonal megakaryocyte dysplasia with normal blood values.

Real-World Dosing Patterns of Ruxolitinib in Patients With Polycythemia Vera Who Are Resistant to or Intolerant of Hydroxyurea

INTRODUCTION

Approximately one-quarter of patients with polycythemia vera become resistant to and/or intolerant of hydroxyurea. This analysis characterizes reasons patients were switched from hydroxyurea to ruxolitinib and describes ruxolitinib dosing patterns and outcomes in real-world clinical practice.

PATIENTS AND METHODS

This medical chart review of United States community hematology/oncology practices in the Cardinal Health Oncology Provider Extended Network included patients with polycythemia vera who were ≥18 years old, received hydroxyurea for ≥3 months, started ruxolitinib between January 1, 2015 and December 31, 2016, and had ≥2 visits during the subsequent 6 months. Clinical data were collected at predefined intervals from diagnosis to last provider visit.

RESULTS

Providers identified 249 patients for inclusion. jcauses of hydroxyurea discontinuation were resistance (78%; frequently for hematocrit ≥45% [79%]) and intolerance (28%; frequently for nausea/vomiting [50%]). Initial ruxolitinib dosing was 10 mg twice daily (recommended dose) in 131 patients (53%). Among these patients, median treatment duration was 29.2 months, 35 (27%) had dose modification (increase, n = 24; decrease, n = 11) and 4 had interruptions within 6 months. The most common reason for dose increase was continued need for phlebotomy (46%); 6 patients had dose reductions owing to reduced platelets. Hematocrit control at initiation and during the first 6 months of ruxolitinib treatment was 15% and 63%, respectively.

CONCLUSION

Most patients initiated ruxolitinib upon hydroxyurea resistance. Approximately half initiated ruxolitinib at the recommended dose, 27% of whom experienced dosing modifications within the first 6 months. After switching to ruxolitinib, most patients achieved hematocrit control and continued treatment for extended time frames.

Stepping out of antiquity: An update on emerging drugs for the treatment of polycythemia vera

Introduction: Polycythemia vera is a chronic hematologic malignancy frequently presented with constitutional symptoms and associated with an increased risk of thrombosis, hemorrhage, and progression to myelofibrosis or acute myeloid leukemia. Current treatment strategies reduce thrombohemorrhagic risk by controlling blood counts and inhibiting platelets, but often fail to address disease-related symptoms or biologically modify the disease.Areas covered: We review the current paradigm for treating polycythemia vera, highlight areas of unmet need, review therapeutic agents in late stage clinical development, and provide an overarching view of how these emerging agent may fit into the future armamentarium of polycythemia vera treatments.Expert opinion: The shift from focusing solely on secondary prevention of thrombohemorrhagic events to a comprehensive treatment strategy that additionally aims to improve quality of life and prevent disease progression has resulted in a rapidly evolving therapeutic landscape that promises to move the treatment of polycythemia vera out of antiquity into the modern age.

Current Concepts of Pathogenesis and Treatment of Philadelphia Chromosome-Negative Myeloproliferative Neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms are hematopoietic stem cell disorders characterized by dysregulated proliferation of mature myeloid blood cells. They can present as polycythemia vera, essential thrombocythemia, or myelofibrosis and are characterized by constitutive activation of JAK2 signaling. They share a propensity for thrombo-hemorrhagic complications and the risk of progression to acute myeloid leukemia. Attention has also been drawn to JAK2 mutant clonal hematopoiesis of indeterminate potential as a possible precursor state of MPN. Insight into the pathogenesis as well as options for the treatment of MPN has increased in the last years thanks to modern sequencing technologies and functional studies. Mutational analysis provides information on the oncogenic driver mutations in JAK2, CALR, or MPL in the majority of MPN patients. In addition, molecular markers enable more detailed prognostication and provide guidance for therapeutic decisions. While JAK2 inhibitors represent a standard of care for MF and resistant/refractory PV, allogeneic hematopoietic stem cell transplantation remains the only therapy with a curative potential in MPN so far but is reserved to a subset of patients. Thus, novel concepts for therapy are an important need, particularly in MF. Novel JAK2 inhibitors, combination therapy approaches with ruxolitinib, as well as therapeutic approaches addressing new molecular targets are in development. Current standards and recent advantages are discussed in this review.

Interplay between LPA2 and LPA3 in LPA-mediated phosphatidylserine cell surface exposure and extracellular vesicles release by erythrocytes

Evidence is growing for the role of red blood cells (RBCs) in vascular homeostasis, including thrombogenic events and inflammation. Lysophosphatidic acid (LPA) is known to induce phosphatidylserine (PS) exposure and the release of RBC Extracellular Vesicles (REVs). Using high sensitivity flow cytometry, we examined the effects and the mechanisms by which the LPA species commonly found in human plasma could activate RBCs. We report that LPA 16:0, 18:0 and 18:1, but not LPA 20:4, induced PS exposure and the release of small PS^- and large PS⁺ REVs through LPA3 receptor signalling in RBCs. The release of large PS⁺ REVs required higher concentrations of LPA. RBCs were not activated by LPA 20:4. Interestingly, blockade of LPA2 enhanced LPA-mediated PS^- REV release in RBCs. Furthermore, LPA receptor agonists and antagonists highlighted that LPA 20:4 inhibited LPA3-dependent PS exposure and, through the LPA2 receptor, inhibited PS^- REV production. Activation of RBCs with LPA 18:1 in normal plasma stimulated the release of PS^- and PS⁺ REVs. REVs released in response to LPA were similar to those found in the plasma of systemic lupus erythematosus patients. Our results suggest that LPA species exhibit different biological activities in RBCs through targeting LPA2 and/or LPA3 receptors.

Successful use of phlebotomy to treat severe secondary polycythemia due to chronic lung disease

Secondary polycythemia (SP) occurs as a result of increase erythropoietin levels most commonly as a result of tissue hypoxia. Symptoms such as erythromelalgia, pruritis, and bleeding, which are frequently seen in polycythemia vera (PV), do not commonly occur in SP. Phlebotomy is considered one of the mainstays of therapy for PV but is rarely used for treatment of SP due to concern about worsening tissue hypoxia. We present the case of a patient with severe SP due to chronic hypoxic lung disease who presented with erythromelalgia, pruritis, and bleeding and was treated successfully with therapeutic phlebotomy. This case illustrates the importance of considering the use of therapeutic phlebotomy in symptomatic patients with severe SP.

Interferon alpha therapy in essential thrombocythemia and polycythemia vera-a systematic review and meta-analysis

Data on the efficacy and safety of interferon (IFN)-α for the treatment of essential thrombocythemia (ET) and polycythemia vera (PV) are inconsistent. We conducted a systematic review and meta-analysis and searched MEDLINE and EMBASE via Ovid, Scopus, COCHRANE registry of clinical trials, and Web of Science from inception through 03/2019 for studies of pegylated IFN (peg-IFN) and non-pegylated IFN (non-peg-IFN) in PV and ET patients. Random-effects models were used to pool response rates for the primary outcome of overall response rate (ORR) defined as a composite of complete response, partial response, complete hematologic response (CHR) and partial hematologic response. Peg-IFN and non-peg-IFN were compared by meta-regression analyses. In total, 44 studies with 1359 patients (730 ET, 629 PV) were included. ORR were 80.6% (95% confidence interval: 76.6-84.1%, CHR: 59.0% [51.5%-66.1%]) and 76.7% (67.4-84.0%; CHR: 48.5% [37.8-59.4%]) for ET and PV patients, respectively. In meta-regression analyses results did not differ significantly for non-peg-IFN vs. peg-IFN. Annualized rates of thromboembolic complications and treatment discontinuation due to adverse events were low at 1.2% and 8.8% for ET and 0.5% and 6.5% for PV patients, respectively. Both peg-IFN and non-peg-IFN can be effective and safe long-term treatments for ET and PV.

Haematocrit level in obesity hypoventilation syndrome: a predictor of mortality?

BACKGROUND

The connection between obstructive sleep apnea and secondary erythrocytosis is controversial. We hypothesised that there may be a higher prevalence of erythrocytosis in patients with obesity hypoventilation syndrome (OHS) due to persistent hypoxemia.

METHODS

The study was a retrospective, cross-sectional review of patients with OHS derived from an established cohort of "non-invasive ventilation" patients at the Department of Sleep Medicine at the Royal Infirmary Medical Centre, Edinburgh (2004-2017). Relevant clinical data were obtained from patient records.

RESULTS

The cohort comprised 74 patients with OHS, 44 men (60%), mean age at diagnosis 54 ± 10 years. The mean haematocrit level for the group overall was 0.44, in men 0.45, and in women 0.41. Of 11 patients with erythrocytosis (15%), 7 were men. Thirteen patients (18%) died during follow-up (2004-2017). There was a statistically significant increase in risk of death in patients with higher and lower haematocrit levels compared to that in patients with OHS who had normal haematocrits.

CONCLUSIONS

This is the first study showing increased prevalence of erythrocytosis in OHS patients. There was a "U"-shaped correlation with mortality according to haematocrit levels.

Emerging agents and regimens for polycythemia vera and essential thrombocythemia

Polycythemia vera (PV) and essential thrombocythemia (ET) are both driven by JAK-STAT pathway activation and consequently much of the recent research efforts to improve the management and outcomes of patients with these neoplasms have centered around inhibition of this pathway. In addition to newer JAK inhibitors and improved interferons, promising novel agents exploiting a growing understanding of PV and ET pathogenesis and disease evolution mechanisms are being developed. These agents may modify the disease course in addition to cytoreduction. Histone deacetylase, MDM2 and telomerase inhibitors in patients with PV/ET have demonstrated clinically efficacy and serve as chief examples. Hepcidin mimetics, limiting iron availability to red blood cell precursors, offer an exciting alternative to therapeutic phlebotomy and have the potential to revolutionize management for patients with PV. Many of these newer agents are found to improve hematologic parameters and symptom burden, but their role in thrombotic risk reduction and disease progression control is currently unknown. The results of larger, randomized studies to confirm the early efficacy signals observed in phase 1/2 trials are eagerly awaited.

Clinical, laboratory, and genetic risk factors for thrombosis in sickle cell disease

Sickle cell disease (SCD) patients are at a four- to 100-fold increased risk for thrombosis compared with the general population, although the mechanisms and risk factors are not clear. We investigated the incidence and predictors for thrombosis in a retrospective, longitudinal cohort of 1193 pediatric and adult SCD patients treated at our institution between January 2008 and December 2017. SCD diagnosis and thrombotic complications were identified using International Classification of Diseases coding and verified through medical chart review. Clinical and laboratory data were extracted from the medical records. With a median follow-up of 6.4 years, 208 (17.4%) SCD patients experienced 352 thrombotic events (64 strokes, 288 venous thromboembolisms [VTE]). Risk factors for stroke included older age and HbSS/Sβ0-genotype and a lower hemoglobin (Hb) F% in the subset of HbSS/Sβ0-genotype patients (P < .05). VTE risk was independently associated with lower estimated glomerular filtration rate, hydroxyurea (HU) use, HbSS/Sβ0 genotype, and higher white blood cell (WBC) counts and Hb (P ≤ .03). Two thrombomodulin gene variants previously associated with thrombosis in the general African American population, THBD rs2567617 (minor allele frequency [MAF] 0.25; odds ratio [OR], 1.5; P = .049) and THBD rs1998081 (MAF, 0.24; OR, 1.5; P = .059), were associated with thrombosis in this cohort. In summary, thrombotic complications are common, and several traditional and SCD-specific risk factors are associated with thrombotic risk. Future studies integrating clinical, laboratory, and genetic risk factors may improve our understanding of thrombosis and guide intervention practices in SCD.

Management of hydroxyurea resistant or intolerant polycythemia vera

Polycythemia vera is a Philadelphia negative myeloproliferative neoplasm characterized by erythrocytosis in which the major cause of morbidity and mortality is thrombosis. Aspirin and hematocrit reduction by venesection or cytoreductive therapy are at the cornerstone of management. First line cytoreductive therapy in high-risk patients is hydroxyurea; however, its use is associated with toxicities and resistance in a significant proportion of patients. In a disease with a long overall survival with appropriate treatment, it is imperative that other treatment options do not accelerate the risk of progression to acute leukemia. The following review will appraise the evidence of interferon, ruxolitinib, and other agents in management of hydroxyurea resistant or intolerant polycythemia vera.