The risk of thrombosis in patients with acute leukemia: occurrence of thrombosis at diagnosis and during treatment

Venous thromboembolism in patients with acute leukemia: incidence, risk factors, and effect on survival

A population-based cohort was used to determine the incidence and risk factors associated with development of venous thromboembolism (VTE) among Californians diagnosed with acute leukemia between 1993 to 1999. Principal outcomes were deep vein thrombosis in both the lower and upper extremities, pulmonary embolism, and mortality. Among 5394 cases with acute myelogenous leukemia (AML), the 2-year cumulative incidence of VTE was 281 (5.2%). Sixty-four percent of the VTE events occurred within 3 months of AML diagnosis. In AML patients, female sex, older age, number of chronic comorbidities, and presence of a catheter were significant predictors of development of VTE within 1 year. A diagnosis of VTE was not associated with reduced survival in AML patients. Among 2482 cases with acute lymphoblastic leukemia (ALL), the 2-year incidence of VTE in ALL was 4.5%. Risk factors for VTE were presence of a central venous catheter, older age, and number of chronic comorbidities. In the patients with ALL, development of VTE was associated with a 40% increase in the risk of dying within 1 year. The incidence of VTE in acute leukemia is appreciable, and is comparable with the incidence in many solid tumors.

Cerebral sinus venous thrombosis complicated by cerebellar hemorrhage in a child with acute promyelocytic leukemia

A 12-year-old boy who presented with headache and papilledema was diagnosed with cerebral sinus venous thrombosis and promyelocytic leukemia. Cerebral sinus venous thrombosis is an uncommon manifestation of acute promyelocytic leukemia, and acute promyelocytic leukemia is an unusual etiology for cerebral sinus venous thrombosis. This case highlights the importance of a complete evaluation for risk factors in a child presenting with cerebral sinus venous thrombosis. Anticoagulation was initiated for treatment of cerebral sinus venous thrombosis, and new asymptomatic hemorrhage was identified in the cerebellum 1 day later. Anticoagulation was discontinued for 5 days and then reinitiated in the intensive care unit without hemorrhage expansion or other complications. We review the literature regarding anticoagulation in children with cerebral sinus venous thrombosis and issues specific to acute promyelocytic leukemia. This case suggests that in a controlled setting, anticoagulation may be safe in selected patients with cerebellar hemorrhage.

Acute thrombosis in superior mesenteric artery as first symptom in a AML patient

It is well known that acute leukemia may accompany thromboembolic events; even severe thrombocytopenia does not prevent thrombosis. Coagulation dysfunction is the major pathophysiological background for thromboembolism in these patients. Most thromboembolism is localized in venous vessels in acute leukemic patients and it happens rarely in the artery. We report a case of acute thrombosis in the superior mesenteric artery as the first symptom in a patient suffering from acute myeloid leukemia (FAB M4).

Anaphylaxis and superior vena cava thrombus in a pediatric patient with acute lymphoblastic leukemia

Pediatric patients with malignancies are at significant risk for complications from their underlying condition and medical therapy. Emergency medicine physicians must be quick to suspect life-threatening events, which can present insidiously. We describe a case of anaphylaxis and superior vena cava syndrome in an 18-year-old female patient after polyethylene glycol-conjugated asparaginase chemotherapy for acute lymphoblastic leukemia. Pertinent literature surrounding risk factors, diagnosis, and treatment is also reviewed.

The incidence of and risk factors for venous thromboembolism (VTE) and bleeding among 1514 patients undergoing hematopoietic stem cell transplantation: implications for VTE prevention

Venous thromboembolism (VTE) is increasingly diagnosed among individuals with hematologic malignancies. However, the risk of VTE among patients undergoing hematopoietic stem cell transplantation (HSCT) is unclear. We examined the incidence and risk factors for VTE and bleeding among 1514 patients undergoing in-patient HSCT. No protocolized VTE prophylaxis was used. By HSCT day 180, 75 symptomatic VTE occurred in 70 patients (4.6%; 95% confidence interval [CI], 3.6%-5.8%). Fifty-five (3.6%) were catheter-associated, 11 (0.7%) were non-catheter-associated deep venous thromboses, and 9 (0.6%) were pulmonary emboli. Thirty-four percent of VTE occurred at a platelet count less than 50 x10(9)/L; 13% occurred at a platelet count less than 20 x10(9)/L. In multivariate analysis, VTE was associated with prior VTE (odds ratio [OR], 2.9; 95% CI, 1.3-6.6) and with graft-versus-host disease (GVHD; OR, 2.4; 95% CI, 1.4-4.0). Clinically significant bleeding occurred in 230 patients (15.2%; 95% CI, 13.4%-17.1%); 55 patients (3.6%; 95% CI, 2.7%-4.7%) had fatal bleeding. Bleeding was associated with anticoagulation (OR, 3.1; 95% CI, 1.8-5.5), GVHD (OR, 2.4; 95% CI, 1.8-3.3), and veno-occlusive disease (OR, 2.2; 95% CI, 1.4-3.6). In HSCT patients, VTE is primarily catheter-related and 3-fold less common than clinically significant bleeding. These findings warrant consideration when selecting VTE prophylaxis in HSCT patients.

Bleeding and thrombosis in acute leukemia: what does the future of therapy look like?

Bleeding and thrombosis are major risk factors for early death in patients with acute leukemia; chemotherapy increases the likelihood of both of these complications. Patients with acute leukemia often present with a hypercoagulable state or with evidence for chronic disseminated intravascular coagulation, even in the absence of active thrombosis and/or bleeding. Leukemic cell procoagulant properties, cytotoxic therapies, and concomitant infections are major determinants of clotting activation in acute leukemia. Clinical manifestations range from localized venous or arterial thrombosis to diffuse life-threatening bleeding. All-trans retinoic acid has greatly improved the management of acute promyelocytic leukemia, but has not significantly changed the rate of early hemorrhagic deaths and may actually promote thrombosis. Randomized, controlled trials of different prophylactic regimens to prevent thrombosis and/or bleeding in acute leukemia are urgently needed, particularly in patients with acute promyelocytic leukemia. Anticoagulant therapy is a unique challenge in patients with acute leukemia, who are at high risk for hemorrhage. Although no guidelines are available for prophylaxis or treatment of thrombosis, extrapolation can be made from existing guidelines for management of patients with other malignancies prolonged periods of treatment-induced thrombocytopenia in patients with acute leukemia, however, require a more judicious application of standard anticoagulant approaches. Use of the newer anticoagulants will require careful assessment of hemorrhagic risk in this group of high risk patients but may be justified under special circumstances.

Antiangiogenic activity of thalidomide in combination with fludarabine, carboplatin, and topotecan for high-risk acute myelogenous leukemia

Forty-two patients with poor prognosis AML were enrolled in a phase II study combining fludarabine, carboplatin, and topotecan (FCT) with thalidomide. Laboratory correlates included serum vascular endothelial growth factor levels (VEGF) and bone marrow microvascular density (MVD). Ten of 42 (24%) patients achieved a complete remission (CR or CRp). Serious thrombotic adverse events were observed in 5 patients suggesting that the combination of cytotoxic chemotherapy and thalidomide may be thrombogenic despite significant thrombocytopenia. VEGF did not correlate with response to therapy, while a trend towards decreased MVD was noted in patients who achieved CR. The addition of thalidomide did not significantly influence angiogenic markers. It is not clear that thalidomide adds any efficacy to the FCT regimen.

Clinical pharmacology of asparaginases in the United States: asparaginase population pharmacokinetic and pharmacodynamic (PK-PD) models (NONMEM) in adult and pediatric ALL patients

In the past 25 years, effective new drugs along with better treatment decisions based on disease factors have resulted in significantly improved clinical outcomes in acute lymphoblastic leukemia. Despite these successes in the last 2 decades, 15% to 25% of acute lymphoblastic leukemia patients relapse. Therefore, better dosing therapies are still needed. Insights in the pharmacokinetic and pharmacodynamic (PK-PD) contributions of licensed drugs may guide us into better protocol design and optimal use of existing combination drug regimens. Currently, 3 asparaginase formulations are available in the United States, Escherichia coli native asparaginase (ASNase), Pegaspargase, and Erwinase. On the basis of these clinical studies, PK and PD population modeling (NONMEM) have been used to delve into new insights as to the optimal dose, formulation, and time intervals of ASNases that may be used in future clinical trials. Pegaspargase 2500 IU/m2 Q2week dosing seems to be the "golden standard" as far as being safe and effective. Lower doses of this formulation Qweek may achieve better PK "steady-state" profiles in serum. Native E. coli or Erwinia ASNase at 6000 IU/m2 showed inferior PK parameters (peak, trough, and area under the curve) than Pegaspargase. Assuming linear handling of ASNase modeling, simulations of higher doses of these ASNase formulations on a daily or Q48 hours regimen are showing bioequivalency with Pegaspargase PK-PD parameters. Future clinical trial designs may prove these efforts useful.

Symptomatic venous thromboembolism and thrombophilic status in adult acute leukemia: a single-center experience of 114 patients at diagnosis

Inherited and acquired thrombophilia are associated with venous thromboembolic events (TE). The prevalence of inherited and acquired prothrombotic risk factors and the incidence of symptomatic TE were evaluated in a cohort of 114 adult acute leukemia patients. The most frequent prothrombotic risk factor was hyperhomocysteinemia which occurred in 46.6% of patients. The incidence of TE was 9.6%, mainly in the first month of follow-up. In multivariate analysis, hyperhomocysteinemia was the only risk factor for TE (OR 33.90; 95% CI 1.53-751.33; p = 0.026). The results of this study indicate that measurements of homocysteinemia could be useful in determining the risk of early TE in adult acute leukemia patients, while systematic thrombophilia screening should not be justified.

Management of Thrombohemorrhagic Syndromes (THS) in Hematologic Malignancies

The rate of venous thromboembolism (VTE) in patients with acute leukemia or lymphomas is comparable with that of other “high-risk” cancer types. Chemotherapy and anti-angiogenic drugs increase the thrombotic risk in patients with lymphomas, acute leukemias and multiple myeloma (MM). Patients with hematologic malignancies often present with a hypercoagulable state or chronic disseminated intravascular coagulation (DIC) in the absence of active thrombosis and/or bleeding. Malignant cell procoagulant properties, cytotoxic therapies, and concomitant infections are major determinants for clotting activation in hematologic malignancies. In acute leukemia, clinical manifestations range from localized venous or arterial thrombosis to a diffuse, life-threatening thrombohemorrhagic syndrome (THS). All-trans retinoic acid (ATRA) has greatly improved the management of acute promyelocytic leukemia (APL), but has not significantly changed the rate of early hemorrhagic deaths and may actually promote thrombosis. Randomized, controlled trials (RCTs) of different prophylactic regimens to prevent VTE or THS in hematologic malignancies are urgently needed, particularly in patients with lymphoma or MM during chemotherapy and in patients with APL. Anticoagulant therapy is a particular challenge in patients with hematologic malignancies, since these patients are at very high risk for hemorrhage. No guidelines are available for the prophylaxis or treatment of VTE; extrapolations can be made from existing guidelines for management of patients with other malignancies; prolonged periods of treatment-induced thrombocytopenia in patients with hematologic malignancies, however, require a more judicious application of standard anticoagulant approaches. Use of the newer anticoagulants will require careful assessment of hemorrhagic risk in this group of high-risk patients but may be justified under special circumstances.

Double Hazard of Thrombophilia and Bleeding in Leukemia

The association between thrombosis and cancer has been extensively studied since first pointed out by Trousseau in 1895. It is, however, not commonly appreciated that the incidence of thrombosis in malignant hematologic disorders is as high or even higher than in solid tumors. Thrombotic complications in acute leukemia are often overlooked because bleeding complications generally dominate the clinical picture. Yet, the patient is at risk for both. While there are many thrombogenic factors shared by both solid tumors and leukemia, many additional prothrombotic features are present in leukemia. The prothrombotic factors include hyperleukocytosis, increased expression of tissue factor and its activation in leukemic cells, and the prothrombotic adverse effects of therapeutic agents and vascular access catheters. In addition, comorbid conditions including hereditary thrombophilia, infection, endothelial cell activation by cytokines, antiphospholipid syndrome and acquired activated protein C resistance are major contributory factors. Factors that increase the bleeding risk include thrombocytopenia, disseminated intravascular coagulation, and excessive fibrinolysis, which is enhanced by increased expression of Annexin II by leukemic cells. Therapeutic approaches to both bleeding and thrombotic conditions require special considerations of these factors.

Occurrence of thrombotic events in acute promyelocytic leukemia correlates with consistent immunophenotypic and molecular features

Although the occurrence of thrombosis in acute promyelocytic leukemia (APL) has been reported during retinoic acid treatment, no studies carried out in large clinical cohorts have specifically addressed this issue. We analyzed 124 APL patients treated with the all-trans retinoic acid and idarubicin protocol and compared clinico-biologic characteristics of 11 patients who developed thrombosis with those of 113 patients who had no thrombosis. In seven patients, the events were recorded during induction, whereas in four patients deep vein thrombosis occurred in the post-induction phase. Comparison of clinico-biological characteristics of patients with and without thrombosis revealed in the former group higher median white blood cell (WBC) count (17 x 10(9)/l, range 1.2-56, P=0.002), prevalence of the bcr3 transcript type (72 vs 48%, P=0.01), of FLT3-ITD (64 vs 28%, P=0.02), CD2 (P=0.0001) and CD15 (P=0.01) expression. No correlation was found with sex, age, French-American-British subtype, all-trans-retinoic acid syndrome or with thrombophilic state that was investigated in 5/11 patients. Our findings suggest that, in APL patients consistent biologic features of leukemia cells may predict increased risk of developing thrombosis.

L-asparaginase-induced antithrombin type I deficiency: implications for conformational diseases

Serpinopathies, a group of diseases caused by mutations that disrupt the structurally sensitive serpins, have no known acquired cause. Interestingly, l-asparaginase treatment of acute lymphoblastic leukemia patients causes severe deficiency in the serpin antithrombin. We studied the consequences of this drug on antithrombin levels, activity, conformation, and immunohistological and ultrastructural features in plasma from acute lymphoblastic leukemia patients, HepG2 cells, and plasma and livers from mice treated with this drug. Additionally, we evaluated intracellular deposition of alpha1-antitrypsin. l-Asparaginase did not affect functional or conformational parameters of mature antithrombin; however, patients and mice displayed severe type I deficiency with no abnormal conformations of circulating antithrombin. Moreover, l-asparaginase impaired secretion of antithrombin by HepG2 cells. These effects were explained by the intracellular retention of antithrombin, forming aggregates within dilated endoplasmic reticulum cisterns. Similar effects were observed for alpha1-antitrypsin in plasma, cells, and livers, and intracellular aggregates of additional proteins were observed in frontal cortex and pancreas. This is the first report of a conformational drug-associated effect on serpins without genetic factors involved. l-Asparaginase treatment induces severe, acquired, and transient type I deficiency of antithrombin (and alpha1-antitrypsin) with intracellular accumulation of the nascent molecule, increasing the risk of thrombosis.

Thrombotic complications in childhood acute lymphoblastic leukemia: a meta-analysis of 17 prospective studies comprising 1752 pediatric patients

The risk of thrombosis in children with acute lymphoblastic leukemia (ALL) reportedly ranges between 1% and 37%. Epidemiologic studies have usually been hampered by small numbers, making accurate estimates of thrombosis risk in ALL patients very difficult. The aim of this study was to better estimate the frequency of this complication and to define how the disease, its treatment, and the host contribute to its occurrence. We made an attempt to combine and analyze all published data on the association between pediatric ALL and thrombosis, by using a meta-analytic method. The rate of thrombosis in 1752 children from 17 prospective studies was 5.2% (95% CI: 4.2-6.4). The risk varies depending on several factors. Most of the events occurred during the induction phase of therapy. Lower doses of asparaginase (ASP) for long periods were associated with the highest incidence of thrombosis, as were anthracyclines and prednisone (instead of dexamethasone). The presence of central lines and of thrombophilic genetic abnormalities also appeared to be frequently associated with thrombosis. In conclusion, the overall thrombotic risk in ALL children was significant, and the subgroup analysis was able to identify high-risk individuals, a finding that will hopefully guide future prospective studies aimed at decreasing this risk.

Increased risk of venous thromboembolism in patients with acute leukaemia

Patients with malignancies have an increased risk for venous thromboembolisms (VTE), but data on patients with acute leukaemia are very limited so far. We found VTE in 12% of 455 patients with acute leukaemia, half of which occurred in association with central venous catheters, with equal risk of ALL and AML.

The pathogenesis of venous thromboembolism in cancer: emerging links with tumour biology

Venous thromboembolism (VTE) is a frequent complication in individuals with cancer and is considered to be a cause of substantial mortality. Epidemiological studies identify malignancy as an independent VTE risk factor and show that cancer patients are at increased risk of both initial and recurrent VTE events. The risk due to cancer is compounded by the effects of chemotherapy and other treatments. The pathogenesis of cancer-associated VTE is complex involving multiple interactions between tumours and various components of haemostasis. The development of a systemic hypercoagulable state is considered a key pathogenetic feature and is attributed to tumour expression of tissue factor and other procoagulants, activation of vascular cells by tumour-derived cytokines and adhesive interactions between tumour cells and host cells. An increasing body of evidence indicates that the activation of haemostasis in malignant disease contributes to tumour growth and progression by stimulation of intracellular signalling pathways. The interaction of tissue factor, thrombin and other coagulation factors with protease activated receptor (PAR) proteins expressed by tumour cells and host vascular cells leads to the induction of genes related to the processes of angiogenesis, cell survival and cell adhesion and migration.