Risk for Arterial and Venous Thrombosis in Patients With Myeloproliferative Neoplasms: A Population-Based Cohort Study

Venous thromboembolism in cancer patients: Still looking for answers

Patients with cancer-associated venous thromboembolism (VTE) represent a real challenge in clinical practice. Patients with cancer have a greater risk both of VTE and bleeding. There are only a few studies regarding the therapeutic approach of VTE in patients with cancer, especially after cancer surgery, and on thromboprophylaxis during chemotherapy. Many of the anticoagulation therapy recommendations for cancer patients are extrapolated from trials that are not conducted in cancer cohorts. It is essential to assess the efficacy and safety of VTE prophylaxis in this particular subgroup, which bears higher risks both of VTE recurrence and major hemorrhagic events. The introduction of direct oral anticoagulants in everyday practice represented a major evolution of the anticoagulant treatment. Direct anticoagulants could represent a more appealing alternative to low-molecular-weight heparin in paraneoplastic venous thrombosis, due to the patient comfort, easy administration of the drug and emerging studies that prove similar efficacy and safety as the standard treatment. However, there is limited data on the treatment with direct oral anticoagulants in patients with paraneoplastic venous thromboembolism.

The impact of phlebotomy and hydroxyurea on survival and risk of thrombosis among older patients with polycythemia vera

Current guidelines recommend therapeutic phlebotomy for all polycythemia vera (PV) patients and additional cytoreductive therapy (eg, hydroxyurea [HU]) for high-risk PV patients. Little is known about the impact of these therapies in the real-world setting. We conducted a retrospective cohort study of older adults diagnosed with PV from 2007 to 2013 using the linked Surveillance, Epidemiology, and End Results-Medicare database. Multivariable Cox proportional hazards models were used to assess the effect of phlebotomy and HU on overall survival (OS) and the occurrence of thrombotic events. Of 820 PV patients (median age = 77 years), 16.3% received neither phlebotomy nor HU, 23.0% were managed with phlebotomy only, 19.6% with HU only, and 41.1% with both treatments. After a median follow-up of 2.83 years, 37.2% (n = 305) of the patients died. Phlebotomy (yes/no; hazard ratio [HR] = 0.65; 95% confidence interval [CI], 0.51-0.81; P < .01), increasing phlebotomy intensity (HR = 0.71; 95% CI, 0.65-0.79; P < .01), and a higher proportion of days covered (PDC) by HU were all significantly associated with lower mortality. When thrombosis was the outcome of interest, phlebotomy (yes/no; HR = 0.52; 95% CI, 0.42-0.66; P < .01) and increasing phlebotomy intensity (HR = 0.46; 95% CI, 0.29-0.74; P < .01) were significantly associated with a lower risk of thrombotic events, so was a higher HU PDC. In this population-based study of older adults with PV reflecting contemporary clinical practice, phlebotomy and HU were associated with improved OS and decreased risk of thrombosis. However, both treatment modalities were underused in this cohort of older PV patients.

Addressing and proposing solutions for unmet clinical needs in the management of myeloproliferative neoplasm-associated thrombosis: A consensus-based position paper

This article presents the results of a group discussion among an ad hoc constituted Panel of experts aimed at highlighting unmet clinical needs (UCNs) in the management of thrombotic risk and thrombotic events associated with Philadelphia-negative myeloproliferative neoplasms (Ph-neg MPNs). With the Delphi technique, the challenges in Ph-neg MPN-associated thrombosis were selected. The most clinically relevant UCNs resulted in: (1) providing evidence of the benefits and risks of direct oral anticoagulants, (2) providing evidence of the benefits and risks of cytoreduction in patients with splanchnic vein thrombosis without hypercythemia, (3) improving knowledge of the role of the mutated endothelium in the pathogenesis of thrombosis, (4) improving aspirin dosing regimens in essential thrombocythemia, (5) improving antithrombotic management of Ph-neg MPN-associated pregnancy, (6) providing evidence for the optimal duration of anticoagulation for prophylaxis of recurrent VTE, (7) improving knowledge of the association between somatic gene mutations and risk factors for thrombosis, and (8) improving the grading system of thrombosis risk in polycythemia vera. For each of these issues, proposals for advancement in research and clinical practice were addressed. Hopefully, this comprehensive overview will serve to inform the design and implementation of new studies in the field.

How I treat polycythemia vera

Since its discovery, polycythemia vera (PV) has challenged clinicians responsible for its diagnosis and management and scientists investigating its pathogenesis. As a clonal hematopoietic stem cell (HSC) disorder, PV is a neoplasm but its driver mutations result in overproduction of morphologically and functionally normal blood cells. PV arises in an HSC but it can present initially as isolated erythrocytosis, leukocytosis, thrombocytosis, or any combination of these together with splenomegaly or myelofibrosis, and it can take years for a true panmyelopathy to appear. PV shares the same JAK2 mutation as essential thrombocytosis and primary myelofibrosis, but erythrocytosis only occurs in PV. However, unlike secondary causes of erythrocytosis, in PV, the plasma volume is frequently expanded, masking the erythrocytosis and making diagnosis difficult if this essential fact is ignored. PV is not a monolithic disorder: female patients deregulate fewer genes and clinically behave differently than their male counterparts, while some PV patients are genetically predisposed to an aggressive clinical course. Nevertheless, based on what we have learned over the past century, most PV patients can lead long and productive lives. In this review, using clinical examples, I describe how I diagnose and manage PV in an evidence-based manner without relying on chemotherapy.

Characteristics and outcomes of young adults with Philadelphia-negative myeloproliferative neoplasms

OBJECTIVE

Approximately 10% of Philadelphia (Ph)-negative myeloproliferative neoplasms (NPM) are diagnosed at young adulthood. We aim to define the features of this group.

METHODS

A multicenter retrospective study, including patients 18-45 years of age, diagnosed with Ph-negative MPN between 1985 and 2017.

RESULTS

One hundred nine patients were included, 37 with polycythemia vera (34%), 54 with essential thrombocytosis (50%), 15 with primary myelofibrosis (PMF) (14%), and 3 with MPN unclassifiable (3%). Median age was 33 years and 62 (57%) were females. During a median follow-up of 8 years, 39 patients (37%) had at least one thrombotic event. 30/39 of events were venous (77%), 23/30 of which were splanchnic (77%). In 14/39 (36%), thrombosis preceded MPN diagnosis. In a multivariable analysis, only splenomegaly predicted for thrombosis (HR 5.6, CI: 1.4-22). The 10-year risk for secondary myelofibrosis was similar for ET and PV (0.13 vs 0.19, P = 0.51). The 10-year risk for leukemic transformation or mortality was significantly higher for PMF (0.3, P = 0.04).

CONCLUSIONS

The risks of mortality and of progression to MF/leukemia in young adults are similar to older population. Thrombotic events are frequently a presenting sign with a high incidence of venous, in particular splanchnic, events.

Evaluation of platelet function in essential thrombocythemia under different analytical conditions

Background. Studies of platelet aggregation (PA) in essential thrombocythemia (ET) reported contrasting results, likely due to differences in analytical conditions.Objective. We investigated platelet aggregation using different techniques and analytical conditions.Patients and Methods. PA was studied by light-transmission aggregometry (LTA) in platelet-rich plasma (PRP) and impedance aggregometry in PRP and whole blood (WB). ADP, collagen, thrombin receptor activating peptide (TRAP-14) and adrenaline were used as agonists. Since ET patients (n = 41) were on treatment with aspirin (100 mg/d), healthy controls (n = 29) were given aspirin (100 mg/d) for 5 days before testing: therefore, thromboxane A₂-independent PA was tested in all subjects. Blood samples were collected in citrate (C) [low Ca²⁺] or lepirudin (L) [physiological Ca²⁺]; platelet count was adjusted to 250 x 10⁹/L in a set of C-PRP (adjusted C-PRP) and left unmodified in the other samples.Results. Results of PA in 17 ET patients who were poor responders to aspirin (high serum thromboxane B2 levels) were not included in the analysis. With LTA, PA in ET was lower than in controls in adjusted C-PRP and normal in native C-PRP and L-PRP. With impedance aggregometry, PA in L-PRP and L-WB tended to be higher in ET than in controls. Platelet serotonin and ADP contents were reduced in ET. The percentages of circulating platelets expressing P-selectin and platelet-leukocyte hetero-aggregates were higher in ET.Conclusions. Analytical conditions dramatically affect in vitro PA of ET patients, which appears defective under the least physiological conditions and normal/supranormal under conditions that are closer to the physiological.

Impact of Hydroxyurea on Survival and Risk of Thrombosis Among Older Patients With Essential Thrombocythemia

Background: Current guidelines recommend hydroxyurea (HU) as frontline therapy for patients with high-risk essential thrombocythemia (ET) to prevent thrombosis. However, little is known about the impact of HU on thrombosis or survival among these patients in the real-world setting. Patients and Methods: A retrospective cohort study was conducted of older adults (aged ≥66 years) diagnosed with ET from 2007 through 2013 using the linked SEER-Medicare database. Multivariable Cox proportional hazards regression models were used to assess the effect of HU on overall survival, and multivariable competing risk models were used to assess the effect of HU on the occurrence of thrombotic events. Results: Of 1,010 patients, 745 (73.8%) received HU. Treatment with HU was associated with a significantly lower risk of death (hazard ratio [HR], 0.52; 95% CI, 0.43–0.64; P<.01). Every 10% increase in HU proportion of days covered was associated with a 12% decreased risk of death (HR, 0.88; 95% CI, 0.86–0.91; P<.01). Compared with nonusers, HU users also had a significantly lower risk of thrombotic events (HR, 0.51; 95% CI, 0.41–0.64; P<.01). Conclusions: Although underused in our study population, HU was associated with a reduced incidence of thrombotic events and improved overall survival in older patients with ET.

Thromboembolic events in polycythemia vera

Thromboembolic events and cardiovascular disease are the most prevalent complications in patients with polycythemia vera (PV) compared with other myeloproliferative disorders and are the major cause of morbidity and mortality in this population. Moreover, a vascular complication such as arterial or venous thrombosis often leads to the diagnosis of PV. The highest rates of thrombosis typically occur shortly before or at diagnosis and decrease over time, probably due to the effects of treatment. Important risk factors include age (≥ 60 years old) and a history of thrombosis; elevated hematocrit and leukocytosis are also associated with an increased risk of thrombosis. The goal of therapy is to reduce the risk of thrombosis by controlling hematocrit to < 45%, a target associated with reduced rates of cardiovascular death and major thrombosis. Low-risk patients (< 60 years old with no history of thrombosis) are managed with phlebotomy and low-dose aspirin, whereas high-risk patients (≥ 60 years old and/or with a history of thrombosis) should be treated with cytoreductive agents. Interferon and ruxolitinib are considered second-line therapies for patients who are intolerant of or have an inadequate response to hydroxyurea, which is typically used as first-line therapy. In this review, we discuss factors associated with thrombosis and recent data on current treatments, including anticoagulation, highlighting the need for more controlled studies to determine the most effective cytoreductive therapies for reducing the risk of thrombosis in patients with PV.

Thrombosis in the Philadelphia Chromosome-Negative Myeloproliferative Neoplasms

The myeloproliferative neoplasms (MPNs) are clonal stem cell-derived diseases. This chapter focuses on the subcategory of Philadelphia (Ph) chromosome-negative classical MPNs, polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF). These MPNs are associated with both microvascular and macrovascular thrombosis, which may occur in the venous and arterial circulation. Erythrocytosis, leukocytosis, and increased JAK2V617F allele burden are known to be risk factors. In this chapter, we review the thrombotic and hemostatic manifestations of the Philadelphia (Ph) chromosome-negative classical MPNs, including the clinical manifestations, the pathophysiology, as well as management.

Hydroxyurea prevents arterial and late venous thrombotic recurrences in patients with myeloproliferative neoplasms but fails in the splanchnic venous district. Pooled analysis of 1500 cases

We collected 1500 patients with myeloproliferative neoplasms (MPN) and arterial or venous thrombosis (935/565), pooling three independent cohorts previously reported. Long-term treatment with antiplatelet drugs or vitamin K-antagonists (VKA) was given to 1391 (92.7%) patients; 975 (65%) patients received hydroxyurea (HU). We recorded 348 recurrences (venous in 142 cases) over 6075 patient-years, with an incidence rate of 5.7 per 100 pt-years (95% CI 5.1-6.4). The site of the first thrombosis predicted the site of recurrence. Independent factors influencing the rate of novel arterial thrombosis were HU (HR 0.67, 95% CI 0.46-0.98), antiplatelet treatment (HR 0.54, 95% CI 0.35-0.82), and VKA (HR 0.58, 95% CI 0.35-0.96). On the contrary, the recurrence of venous thromboses was significantly diminished only by VKA (HR 0.60, 95% CI 0.37-0.95), while HU prevented late but not early recurrences after venous thrombosis at common sites. Of note, we failed to demonstrate a positive effect of HU in the prevention of recurrent splanchnic vein thrombosis. In conclusion, in MPN patients, HU plays a role in the prevention of arterial thrombosis, together with aspirin and VKA, whereas its action in the prevention of recurrent venous thrombosis is uncertain. Such findings call for future studies to optimize and personalize secondary prophylaxis after MPN-related thrombosis.

Unmasking and aggravation of polycythemia vera by canagliflozin

BACKGROUND

Sodium-glucose co-transporter-2 inhibitors are novel antidiabetes drugs that act via inhibition of renal glucose reabsorption. This action causes osmotic diuresis, reduces intravascular volume and is associated with various adverse effects. In the present paper, we describe the first report on the unmasking of underlying polycythemia vera by canagliflozin in a person with Type 2 diabetes mellitus, which was temporally related to the use of the drug.

CASE REPORT

A 51-year-old obese man with Type 2 diabetes was prescribed canagliflozin 100 mg for control of his glycaemia. He presented 6 months later with asymptomatic elevation of his haemogram measurements (haemoglobin: 16.9 g/dl; haematocrit: 55%; red cell number: 8.1 million/mm³ ; total leukocytes: 23010/mm³ ; platelet count: 9.7 *10⁶ /mm³ ). He had no history of smoking, exposure to high altitude or other drugs. Subsequent investigations revealed myeloproliferative neoplasm (polycythemia vera) on trephine biopsy of bone marrow, normal erythropoietin level and JAK2V617F positivity. Because of the possibility that the underlying condition had been unmasked by canagliflozin, the latter was stopped. This led to a remarkable improvement in the man's haematological profile, with no other significant intervention. The man subsequently restarted the drug of his own accord, causing his haematological profile to worsen again and thereby posing a challenge in monitoring of both polycythemia vera as well as diabetes mellitus.

CONCLUSION

This report brings to light unmasking of a new adverse effect of sodium-glucose co-transporter-2 inhibitors in clinical practice caused by volume loss, apart from hypotension and falls.

Antithrombotic therapy for venous thromboembolism in myeloproliferative neoplasms

In myeloproliferative neoplasms (MPNs) the incidence of venous thromboembolism (VTE) is 0.6–1.0 per 100 pt-years, and the rate of recurrence after VTE is 6.0–6.5 per 100 pt-yrs. Vitamin K-antagonists (VKA) reduces the risk of recurrence after VTE at usual sites (i.e., deep venous thrombosis (DVT) of the legs and pulmonary embolism (PE)) by 48–69%, with a rate of recurrent thrombosis per 100 pt-yrs of 3.4–4.7 on VKA and 8.9–9.6 off VKA; VKA discontinuation produces a 2.2-fold increased risk of novel thrombotic events with respect to continuation. However, the rate of both recurrent thrombosis and major bleeding on VKA is higher in MPN patients than in non-MPN patients, and the risk-benefit balance of long-term VKA treatment is challenging. In the absence of strong evidence, the tailored management of MPN-related VTE should operatively consider the risk categories for recurrence and bleed well established in the non-MPN setting. In summary, MPN patients with VTE are candidates for life-long VKA treatment, especially after unprovoked proximal DVT and PE. Aspirin can offer a moderate benefit in those patients who stop anticoagulation. The use of direct oral anticoagulants should be explored aiming to ameliorate the rate of bleeding.