Effects of all-trans retinoic acid or chemotherapy on the molecular regulation of systemic blood coagulation and fibrinolysis in patients with acute promyelocytic leukemia

Monoclonal antibodies against receptor-induced binding sites detect cell-bound plasminogen in blood

Binding of Glu-plasminogen (the native, circulating form of the zymogen) to cells results in enhancement of its activation. Cell-associated plasmin proteolytic activity is a key component of physiologic and pathologic processes requiring extracellular matrix degradation. Recently, we developed antiplasminogen mAbs that recognize receptor-induced binding sites (RIBS) in Glu-plasminogen and, therefore, preferentially react with cell-associated Glu-plasminogen in the presence of soluble Glu-plasminogen. Here we have used FACS with a representative antiplasminogen receptor-induced binding site mAb, mAb49, to examine whether plasminogen associates with peripheral blood cells in blood. Plasminogen binding to neutrophils, monocytes, B-lymphocytes, T-lymphocytes, and platelets was clearly detected. Treatment of whole blood with lipopolysaccharide or 12-0 tetradecanoylphorbol-13-acetate up-regulated plasminogen binding to neutrophils and in vivo treatment with all-trans retinoic acid decreased plasminogen binding to acute promyelocytic leukemia blasts. Our results demonstrate that mAb49 can be used to monitor cell-bound plasminogen in blood under both normal and pathologic conditions.

The differentiation syndrome in patients with acute promyelocytic leukemia: experience of the pethema group and review of the literature

Differentiation syndrome (DS), formerly known as retinoic acid syndrome, is the main life-threatening complication of therapy with differentiating agents (all-trans retinoic acid [ATRA] or arsenic trioxide [ATO]) in patients with acute promyelocytic leukemia (APL). The differentiation of leukemic blasts and promyelocytes induced by ATRA and/or ATO may lead to cellular migration, endothelial activation, and release of interleukins and vascular factors responsible of tissue damage. Roughly one quarter of patients with APL undergoing induction therapy will develop the DS, characterized by unexplained fever, acute respiratory distress with interstitial pulmonary infiltrates, and/or a vascular capillary leak syndrome leading to acute renal failure. Although the development of the DS, particularly of the severe form, is still associated with a significant increase in morbidity and mortality during induction, the early administration of high-dose dexamethasone at the onset of the first symptoms seems likely to have dramatically reduced the mortality rate of this complication. In this article, we will review the clinical features, incidence, prognostic factors, management, and outcome of the DS reported in the scientific literature. We will make focus in the experience of the three consecutive Programa Español de Tratamientos en Hematología trials (PETHEMA LPA96, LPA99, and LPA2005), in which more than one thousand patients were treated with ATRA plus idarubicin for induction.

Tissue factor-activated coagulation cascade in the tumor microenvironment is critical for tumor progression and an effective target for therapy

Tissue factor (TF), a rate-limiting enzyme cofactor in activating coagulation, is highly expressed in a wide spectrum of human tumor and tumor stromal cells. Using TF-deficient cancer cells and a conditional TF-knockout mouse model, we show that TF expressed by cancer cells, but not by the host stromal cells, plays a critical role in tumor growth. In the tumor microenvironment, serum coagulation factors are readily extravasated and therefore lead to continuous TF-mediated activation of coagulation proteases. To target this highly specific cascade of serine proteases, we used both a TF:VIIa inhibitor and doxorubicin-based prodrugs that are selectively activated by TF:FVIIa, FXa, and thrombin. Treatment with the TF:FVIIa inhibitor led to growth retardation in breast tumor models. In contrast, treatment with the prodrug eliminated primary tumor cells and lung metastases without apparent toxicity. Our findings offer preclinical proof of principle that targeting the coagulation cascade that is activated in the tumor microenvironment can be a highly effective approach for cancer therapy.

Thromboembolic and bleeding complications in acute leukemia

The risk of both thromboembolic and bleeding complications is high in acute leukemia. This double hazard has a significant negative impact on the morbidity and mortality of patients with this disease. The clinical manifestations of both complications show special features specific to the form of acute leukemia. Recognition of these characteristics is important in the diagnosis and management of acute leukemia. In this article, several additional issues are addressed, including the features of bleeding and thrombosis in acute promyelocytic leukemia, the current understanding of the leukostasis syndrome and the iatrogenic complications including catheter-associated thrombosis, and the adverse effects of therapeutic agents used in acute leukemia. As regards the bleeding complications, thrombocytopenia is a major cause. Corrective measures, including recent guidelines on platelet transfusions, are provided.

Regulation of S100A10 by the PML-RAR-α oncoprotein

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia that results from the expression of the promyelocytic leukemia–retinoic acid receptor α (PML-RAR-α) oncoprotein. It is characterized by severe hemorrhagic complications due in part to excessive fibrinolysis, resulting from the excessive generation of the fibrinolytic enzyme, plasmin, at the cell surface of the PML cells. The treatment of patients with all-trans retinoic acid (ATRA) effectively ameliorates the disease by promoting the destruction of the PML-RAR-α oncoprotein. In the present study we show for the first time that the plasminogen receptor, S100A10, is present on the extracellular surface of APL cells and is rapidly down-regulated in response to all-trans retinoic acid. The loss of S100A10 is concomitant with a loss in fibrinolytic activity. Furthermore, the induced expression of the PML-RAR-α oncoprotein increased the expression of cell surface S100A10 and also caused a dramatic increase in fibrinolytic activity. Depletion of S100A10 by RNA interference effectively blocked the enhanced fibrinolytic activity observed after induction of the PML-RAR-α oncoprotein. These experiments show that S100A10 plays a crucial role in the generation of plasmin leading to fibrinolysis, thus providing a link to the clinical hemorrhagic phenotype of APL.

Arsenic trioxide improves event-free and overall survival for adults with acute promyelocytic leukemia: North American Leukemia Intergroup Study C9710

Arsenic trioxide (As(2)O(3)) is a highly effective treatment for patients with relapsed acute promyelocytic leukemia (APL); its role as consolidation treatment for patients in first remission has not been defined. We randomized 481 patients (age ≥ 15 years) with untreated APL to either a standard induction regimen of tretinoin, cytarabine, and daunorubicin, followed by 2 courses of consolidation therapy with tretinoin plus daunorubicin, or to the same induction and consolidation regimen plus two 25-day courses of As(2)O(3) consolidation immediately after induction. After consolidation, patients were randomly assigned to one year of maintenance therapy with either tretinoin alone or in combination with methotrexate and mercaptopurine. Ninety percent of patients on each arm achieved remission and were eligible to receive their assigned consolidation therapy. Event-free survival, the primary end point, was significantly better for patients assigned to receive As(2)O(3) consolidation, 80% compared with 63% at 3 years (stratified log-rank test, P < .0001). Survival, a secondary end point, was better in the As(2)O(3) arm, 86% compared with 81% at 3 years (P = .059). Disease-free survival, a secondary end point, was significantly better in the As(2)O(3) arm, 90% compared with 70% at 3 years (P < .0001). The addition of As(2)O(3) consolidation to standard induction and consolidation therapy significantly improves event-free and disease-free survival in adults with newly diagnosed APL. This trial was registered at clinicaltrials.gov (NCT00003934).

Open issues on bleeding and thrombosis in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia characterized by a specific genetic alteration, affecting the retinoic acid receptor-alpha (RAR-alpha), and leading to the accumulation of the promyelocytic blasts in the bone marrow and blood which is frequently associated with a life-threatening consumptive coagulopathy. The body of biological information on APL establishes this leukemia as a unique entity that has to be promptly recognized to counteract the coagulopathy, especially in light of its striking response to treatment with all-trans retinoic acid. In fact, the current standard for induction therapy results in extremely high antileukemic efficacy, achieving 90 to 95% complete remission rate. However, while primary leukemia resistance has virtually disappeared as a cause of remission induction failure, death due to hemorrhage remains the major problem during the early treatment phase. As a part of the clotting activation commonly present in APL, thrombosis is a less recognized and probably underestimated life-threatening manifestation in patients with this disease. In addition to reviewing the available data on the incidence, outcome and prognostic factors of bleeding and thrombosis in APL, we discuss the current consensus and controversies on the most appropriate management of these complications.

Role of the tissue factor pathway in the biology of tumor initiating cells

Oncogenic transformation and aberrant cellular differentiation are regarded as key processes leading to malignancy. They produce heterogenous cellular populations including subsets of tumour initiating cells (TICs), also known as cancer stem cells (CSCs). Intracellular events involved in these changes profoundly impact the extracellular and systemic constituents of cancer progression, including those dependent on the vascular system. This includes angiogenesis, vasculogenesis, activation of the coagulation system and formation of CSC-related and premetastatic niches. Tissue factor (TF) is a unique cell-associated receptor for coagulation factor VIIa, initiator of blood coagulation, and mediator of cellular signalling, all of which influence vascular homeostasis. Our studies established a link between oncogenic events, angiogenesis and the elevated expression of TF in several types of cancer cells. The latter suggests that cancer coagulopathy and cellular events attributed to the coagulation system may have cancer-specific and genetic causes. Indeed, in human glioma cells, a transforming mutant of the epidermal growth factor receptor (EGFRvIII) triggers not only the expression of TF, but also of its ligand (factor VII) and protease activated receptors (PAR-1 and PAR-2). Consequently, tumour cells expressing EGFRvIII become hypersensitive to contact with blood borne proteases (VIIa, thrombin), which upregulate their production of angiogenic factors (VEGF and IL-8), and contribute to formation of the growth promoting microenvironment (niche). Moreover, TF overexpression accompanies features of cellular aggressiveness such as markers of CSCs (CD133), epithelial-to-mesenchymal transition (EMT) and expression of the angiogenic and prometastatic phenotype. Conversely, TF blocking antibodies inhibit tumour growth, angiogenesis, and especially tumour initiation upon injection of threshold numbers of tumourigenic cells. Likewise, TF depletion in the host compartment (e.g. in low-TF mice) perturbs tumour initiation. These observations suggest that both cancer cells and their adjacent host stroma contribute TF activity to the tumour microenvironment. We postulate that the TF pathway may play an important role in formation of the vascular niche for tumour initiating CSCs, through its procoagulant and signalling effects. Therapeutic blockade of these mechanisms could hamper tumour initiation processes, which are dependent on CSCs and participate in tumour onset, recurrence, drug resistance and metastasis.

Acute promyelocytic leukemia treated with idarubicin complicated by focal segmental glomerulosclerosis

The authors report a 9-year-old boy presenting with a left cerebral ischemic infarction as the first manifestation of acute promyelocytic leukemia. During consolidation chemotherapy, the patient developed nephrotic syndrome and a renal biopsy revealed focal segmental glomerulosclerosis (FSGS). Remission in bone marrow was achieved with chemotherapy, however, new intracranial ischemic areas developed on follow-up. Acute promyelocytic leukemia complicated by FSGS has not been previously reported in children. There may be a relationship between anthracycline treatment and FSGS. Thrombosis could be related with both leukemia and nephrotic syndrome, here thrombosis was the initial symptom, before FSGS was diagnosed.

Rapidly progressing, fatal and acute promyelocytic leukaemia that initially manifested as a painful third molar: a case report

Introduction

Acute promyelocytic leukaemia, an uncommon and devastating subtype of leukaemia, is highly prevalent in Latin American populations. The disease may be detected by a dentist since oral signs are often the initial manifestation. However, despite several cases describing oral manifestations of acute promyelocytic leukaemia and genetic analysis, reports of acute promyelocytic leukaemia in Hispanic populations are scarce. The identification of third molar pain as an initial clinical manifestation is also uncommon. This is the first known case involving these particular features.

Case presentation

A 24-year-old Latin American man without relevant antecedents consulted a dentist for pain in his third molar. After two dental extractions, the patient experienced increased pain, poor healing, jaw enlargement and bleeding. A physical examination later revealed that the patient had pallor, jaw enlargement, ecchymoses and gingival haemorrhage. Laboratory findings showed pancytopaenia, delayed coagulation times, hypoalbuminaemia and elevated lactate dehydrogenase. Splenomegaly was detected on ultrasonography. Peripheral blood and bone marrow analyses revealed a hypercellular infiltrate of atypical promyelocytic cells. Cytogenetic analysis showing genetic translocation t(15;17) further confirmed acute promyelocytic leukaemia. Despite early chemotherapy, the patient died within one week due to intracranial bleeding secondary to disseminated intravascular coagulation.

Conclusion

The description of this unusual presentation of acute promyelocytic leukaemia, the diagnostic difficulties and the fatal outcome are particularly directed toward dental surgery practitioners to emphasise the importance of clinical assessment and preoperative evaluation as a minimal clinically-oriented routine. This case may also be of particular interest to haematologists, since the patient's cytogenetic analysis, clinical course and therapeutic response are well documented.

Genetic Link Between Cancer and Thrombosis

From the beginning of their lives, cancer cells exert a procoagulant activity in their microenvironment, which can extend systemically and become clinically evident as Trousseau's syndrome, the well-known association between tumor and thrombosis. It is becoming clear that the genetic mechanisms responsible for neoplastic transformation (activation of oncogenes such as RAS or MET, and inactivation of tumor suppressor genes such as p53 or PTEN) directly induce the expression of genes controlling hemostasis. Activation of blood coagulation results in a selective advantage for cancer cells, as fibrin provides a scaffold for anchorage and invasion, and coagulation proteins induce receptor-mediated intracellular signals promoting invasive growth. Targeting the tumor procoagulant activity can fight not only a dangerous tumor adverse effect, but also the core mechanisms of cancer onset and progression.

Venous thromboembolism in the hematologic malignancies

Patients with hematologic malignancies are at high risk of thrombotic or hemorrhagic complications. The incidence of these events is greatly variable and is influenced by many factors, including the type of disease, the type of chemotherapy, and the use of a central venous device. As in solid tumors, a number of clinical risk factors have been identified and contribute to the increasing thrombotic rate in hematologic malignancies. Biologic properties of the tumor cells can influence the hypercoagulable state of patients with these malignancies by several mechanisms. Of interest, oncogenes responsible for neoplastic transformation in leukemia also may be involved in clotting activation. Epidemiologic data allow an estimate of the incidence of venous thromboembolism (VTE) in acute leukemia, lymphomas, and multiple myeloma (MM). In this review, we focus on the epidemiology, pathogenesis, and VTE management in these three hematologic malignancies. No recommendation for routine thromboprophylaxis in these conditions, with the exception of MM, is available. Large, prospective, randomized clinical trials are needed to establish the best practice for thromboprophylaxis and treatment of VTE in these types of cancers.

Tissue factor and cancer stem cells: is there a linkage?

A common feature in the progression of multiple human malignancies is the protracted deregulation of the coagulation system, often referred to as cancer coagulopathy. Indeed, cancer cells and their vascular stroma often exhibit procoagulant properties, of which deregulation of tissue factor (TF) expression is a notable, although not the sole example. These changes can be traced to oncogenic influences affecting epidermal growth factor receptor (EGFR), EGFRvIII, K-ras, p53, PTEN, and probably many other proto-oncogenes and tumor suppressors in tumor parenchyma. Cancer stem cells (CSCs)/tumor initiating cells (TICs) are thought to represent the primary target and the main cellular effector through which oncogenic mutations exert their tumor-inducing effects. In so doing, CSCs/TICs depend on interactions with the tumor vasculature, which forms supportive niches for their clonal growth. We postulate that TF contributes to these interactions (directly or indirectly) through procoagulant and signaling effects, the latter executed in concert with juxtaposed protease activated receptors (mainly PAR-1 and PAR-2). TF/PAR system acts as a "blood sensing" mechanism, whereby cancer cells, including CSCs/TICs, may respond to plasma proteases (Factors VIIa, Xa, and IIa) and their related microenvironmental changes (fibrin deposition, activation of platelets). A growing body of still largely circumstantial evidence suggests that these events may contribute to the CSC/TIC niche, which could influence tumor initiation, metastasis, recurrence, and therapeutic intractability. Indeed, certain types of cancer cells harboring markers of CSCs (CD133) exhibit elevated TF expression and depend on this receptor to efficiently initiate tumor growth. We propose that both tumor cell-associated and host-related TF could influence the properties of CSCs, and that agents targeting the TF/PAR system may represent a hitherto unappreciated therapeutic opportunity to control cancer progression by influencing the CSC/TIC compartment.

Tissue factor in tumour progression

The linkage between activation of the coagulation system and cancer is well established, as is deregulation of tissue factor (TF) by cancer cells, their vascular stroma and cancer-associated inflammatory cells. TF is no longer perceived as an 'alternative' coagulation factor, but rather as a central trigger of the coagulation cascade and an important cell-associated signalling receptor activated by factor VIIa, and interacting with several other regulatory entities, most notably protease-activated receptors (PAR-1 and PAR-2). Preclinical studies revealed the role of oncogenic transformation and tumour micro-environment as TF regulators in cancer, along with the impact of this receptor on gene expression, tumour growth, metastasis, angiogenesis and, possibly, formation of the cancer stem cell niche. Increasing interest surrounds the shedding of TF-containing microvesicles from cancer cells, their entry into the circulation and their role in the intercellular transfer of TF activity, cancer coagulopathy and other processes. Recent data also suggest differential roles of cell autonomous versus global effects of TF in various settings. Questions are raised regarding the consequences of TF expression by tumour cells themselves and by their associated host stroma. Progress in these areas may soon begin to impact on clinical practice and, as such, raises several important questions. Can TF be exploited as a therapeutic target in cancer? Where and when may this be safe and beneficial? Is expression of TF in various disease settings useful as a biomarker of cancer progression or the associated hypercoagulability? What clinical questions related to TF are especially worthy of further exploration, at present and in the near future? Some of these developments and questions will be discussed in this chapter.

The coagulopathy of acute promyelocytic leukaemia revisited

Since the initial description of the disease, the life-threatening coagulopathy associated with acute promyelocytic leukaemia (APL) has been the defining clinical characteristic. Historically, this uncommon subtype of acute myeloid leukaemia has been associated with a high mortality rate during induction therapy, most frequently attributable to haemorrhage. Since the introduction of all-trans retinoic acid (ATRA) into the therapy of all patients with APL, disease-free survival and overall survival have improved dramatically, such that the disease is now highly curable. However, induction mortality remains a major problem and haemorrhage still accounts for the majority of such early deaths. Pathogenesis of the coagulopathy is complex and includes disseminated intravascular coagulation (DIC), fibrinolysis and proteolysis. As a result, while the predominant clinical manifestation of the coagulopathy is haemorrhage, thromboembolic events may occur both at presentation and during therapy. A major recent finding is the high expression of annexin II in the leukaemic cells from patients with APL. Annexin II is a protein with high affinity for plasminogen and tissue-type plasminogen activator (tPA), and also acts as a cofactor for plasminogen activation by tPA. As a result, both plasminogen and tPA are increased on the cell surface of the leukaemic cell, increasing plasmin activity. Annexin II is expressed in high amounts in cerebral microvascular endothelial cells, perhaps accounting for the relatively high incidence of intracranial haemorrhage in APL compared with other sites. Microparticles are cell-derived membrane fragments originating from normal cells or released from malignant cells involved in activating coagulation. Recent studies have found that microparticles containing tissue factor, tPA, plasminogen activator inhibitor-1 and annexin II have been found in the plasma of APL patients, suggesting a role in pathogenesis of the coagulopathy. Treatment of the coagulopathy remains primarily supportive. Aggressive transfusions of platelets and cryoprecipitate appear to be important. There is no clear role for the routine use of heparin or antifibrinolytic therapy. The most important factor may be the early introduction of ATRA at the first suspicion of a diagnosis of APL, before it is confirmed genetically.

Tissue factor regulation by epidermal growth factor receptor and epithelial-to-mesenchymal transitions: effect on tumor initiation and angiogenesis

ErbB oncogenes drive the progression of several human cancers. Our study shows that in human carcinoma (A431) and glioma (U373) cells, the oncogenic forms of epidermal growth factor receptor (EGFR; including EGFRvIII) trigger the up-regulation of tissue factor (TF), the transmembrane protein responsible for initiating blood coagulation and signaling through interaction with coagulation factor VIIa. We show that A431 cancer cells in culture exhibit a uniform TF expression profile; however, these same cells in vivo exhibit a heterogeneous TF expression and show signs of E-cadherin inactivation, which is coupled with multilineage (epithelial and mesenchymal) differentiation. Blockade of E-cadherin in vitro, leads to the acquisition of spindle morphology and de novo expression of vimentin, features consistent with epithelial-to-mesenchymal transition. These changes were associated with an increase in EGFR-dependent TF expression, and with enhanced stimulation of vascular endothelial growth factor production, particularly following cancer cell treatment with coagulation factor VIIa. In vivo, cells undergoing epithelial-to-mesenchymal transition exhibited an increased metastatic potential. Furthermore, injections of the TF-blocking antibody (CNTO 859) delayed the initiation of A431 tumors in immunodeficient mice, and reduced tumor growth, vascularization, and vascular endothelial growth factor expression. Collectively, our data suggest that TF is regulated by both oncogenic and differentiation pathways, and that it functions in tumor initiation, tumor growth, angiogenesis, and metastasis. Thus, TF could serve as a therapeutic target in EGFR-dependent malignancies.

Vascular determinants of cancer stem cell dormancy--do age and coagulation system play a role?

The inability of tumour-initiating cancer stem cells (CSCs) to bring about a net increase in tumour mass could be described as a source of tumour dormancy. While CSCs may be intrinsically capable of driving malignant growth, to do so they require compatible surroundings of supportive cells, growth factors, adhesion molecules and energy sources (e.g. glucose and oxygen), all of which constitute what may be referred to as a 'permissive' CSC niche. However, in some circumstances, the configuration of these factors could be incompatible with CSC growth (a 'non-permissive' niche) and lead to their death or dormancy. CSCs and their niches may also differ between adult and paediatric cancers. In this regard the various facets of the tumour-vascular interface could serve as elements of the CSC niche. Indeed, transformed cells with an increased tumour-initiating capability may preferentially reside in specific zones adjacent to tumour blood vessels, or alternatively originate from poorly perfused and hypoxic areas, to which they have adapted. CSCs themselves may produce increased amounts of angiogenic factors, or rely for this on their progeny or activated host stromal cells. It is likely that 'vascular' properties of tumour-initiating cells and those of their niches may diversify and evolve with tumour progression. The emerging themes in this area include the role of vascular (and bone marrow) aging, vascular and metabolic comorbidities (e.g. atherosclerosis) and the effects of the coagulation system (both at the local and systemic levels), all of which could impact the functionality of CSCs and their niches and affect tumour growth, dormancy and formation of occult as well as overt metastases. In this article we will discuss some of the vascular properties of CSCs relevant to tumour dormancy and progression, including: (i) the role of CSCs in regulating tumour vascular supply, i.e the onset and maintenance of tumour angiogenesis; (ii) the consequences of changing vascular demand (vascular dependence) of CSC and their progeny; (iii) the interplay between CSCs and the vascular system during the process of metastasis, and especially (iv) the impact of the coagulation system on the properties of CSC and their niches. We will use the oncogene-driven expression of tissue factor (TF) in cancer cells as a paradigm in this regard, as TF represents a common denominator of several vascular processes that commonly occur in cancer, most notably coagulation and angiogenesis. In so doing we will explore the therapeutic implications of targeting TF and the coagulation system to modulate the dynamics of tumour growth and tumour dormancy.

Tissue factor in cancer

PURPOSE OF REVIEW

Tissue factor is increasingly viewed as an integral part of the vicious circle that links the vascular system with cancer progression at multiple systemic, cellular and molecular levels.

RECENT FINDINGS

The emerging tenet in this area is that oncogenic events/pathways driving the malignant process also stimulate the expression of tissue factor by cancer cells and promote the release of tissue factor-containing microvesicles into the circulation. The combined effects of these changes likely contribute to cancer coagulopathy, cessation of tumour dormancy, aggressive growth, angiogenesis and metastasis, notably through a combination of procoagulant and signalling effects set in motion by tissue factor. As certain tumour-associated host cell types (inflammatory cells, endothelium) may also express tissue factor their contribution is plausible, though poorly understood. Interestingly, tissue factor could be 'shared' between various subsets of cancer and host cells due to intercellular transfer of tissue factor-containing microvesicles. It has recently been proposed that tissue factor may influence the interactions between tumour initiating (stem) cells and their growth or prometastatic niches.

SUMMARY

Whereas targeting tissue factor in cancer is appealing, the prospects in this regard will depend on the identification of disease specific indications, active agents and their safe regimens.

Differentiation syndrome in patients with acute promyelocytic leukemia treated with all-trans retinoic acid and anthracycline chemotherapy: characteristics, outcome, and prognostic factors

Differentiation syndrome (DS) can be a life-threatening complication in patients with acute promyelocytic leukemia (APL) undergoing induction therapy with all-trans retinoic acid (ATRA). Detailed knowledge about DS has remained limited. We present an analysis of the incidence, characteristics, prognostic factors, and outcome of 739 APL patients treated with ATRA plus idarubicin in 2 consecutive trials (Programa Español de Tratamientos en Hematología [PETHEMA] LPA96 and LPA99). Overall, 183 patients (24.8%) experienced DS, 93 with a severe form (12.6%) and 90 with a moderate form (12.2%). Severe but not moderate DS was associated with an increase in mortality. A bimodal incidence of DS was observed, with peaks occurring in the first and third weeks after the start of ATRA therapy. A multivariate analysis indicated that a WBC count greater than 5 x 10(9)/L and an abnormal serum creatinine level correlated with an increased risk of developing severe DS. Patients receiving systematic prednisone prophylaxis (LPA99 trial) in contrast to those receiving selective prophylaxis with dexamethasone (LPA96 trial) had a lower incidence of severe DS. Patients developing severe DS showed a reduced 7-year relapse-free survival in the LPA96 trial (60% vs 85%, P = .003), but this difference was not apparent in the LPA99 trial (86% vs 88%).

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.

The role of tumor-and host-related tissue factor pools in oncogene-driven tumor progression

Oncogenic events play an important role in cancer-related coagulopathy (Trousseau syndrome), angiogenesis and disease progression. This can, in part, be attributed to the up-regulation of tissue factor (TF) and release of TF-containing microvesicles into the pericellular milieu and the circulation. In addition, certain types of host cells (stromal cells, inflammatory cells, activated endothelium) may also express TF. At present, the relative contribution of host- vs tumor-related TF to tumor progression is not known. Our recent studies have indicated that the role of TF in tumor formation is complex and context-dependent. Genetic or pharmacological disruption of TF expression/activity in cancer cells leads to tumor growth inhibition in immunodeficient mice. This occurred even in the case of xenotransplants of human cancer cells, in which TF overexpression is driven by potent oncogenes (K-ras or EGFR). Interestingly, the expression of TF in vivo is not uniform and appears to be influenced by many factors, including the level of oncogenic transformation, tumor microenvironment, adhesion and the coexpression of markers of cancer stem cells (CSCs). Thus, minimally transformed, but tumorigenic embryonic stem (ES) cells were able to form malignant and angiogenic outgrowths in the absence of TF. However, these tumors were growth inhibited in hosts (mice) with dramatically reduced TF expression (low-TF mice). Depletion of host TF also resulted in changes affecting vascular patterning of some, but not all types of tumors. These observations suggest that TF may play different roles growth and angiogenesis of different tumors. Moreover, both tumor cell and host cell compartments may, in some circumstances, contribute to the functional TF pool. We postulate that activation of the coagulation system and TF signaling, may deliver growth-promoting stimuli (e.g. fibrin, thrombin, platelets) to dormant cancer stem cells (CSCs). Functionally, these influences may be tantamount to formation of a provisional (TF-dependent) cancer stem cell niche. As such these changes may contribute to the involvement of CSCs in tumor growth, angiogenesis and metastasis.

Granulocytic sarcoma: an unusual complication of acute promyelocytic leukemia causing cerebellar hemorrhage. Case report

Granulocytic sarcomas are rare tumors that occur primarily in patients with acute myelogenous leukemia or other myeloproliferative disorders, are seldom seen in patients with acute promyelocytic leukemia (APL), and have never been reported to occur in the cerebellum. The authors describe the case of a patient with APL who harbored a hemorrhagic granulocytic sarcoma in the cerebellum. This 39-year-old woman presented with cerebellar ataxia. Magnetic resonance images revealed an intraaxial tumor in the cerebellum. Bone marrow samples showing infiltration by leukemic blast cells and data from hematological tests led to a diagnosis of APL. The patient was treated with chemotherapy and surgery. She had no response to chemotherapy and died of progressive intratumoral hemorrhage. Results of histopathological studies and immunohistochemical staining of the cerebellar tumor confirmed a granulocytic sarcoma. Flow cytometry showed that the blast cells were positive for leukocyte common antigen, CD13, and CD33 markers. Bone marrow cytogenetics revealed that the patient had a 46,XX karyotype. Although no cytogenetic abnormality was present, fluorescence in situ hybridization detected a chimeric fusion of PML and RARA. This is the first report to document a granulocytic sarcoma in the cerebellum as the primary presentation in a patient with APL and abnormal coagulation. As predicted by the unusual clinical manifestations and radiological findings, the patient's survival was short. Although central nervous system complications in patients with APL are rare, the data in this case highlight the need for individualized treatment when such conditions occur.

Severe hemorrhagic complications during remission induction therapy for acute promyelocytic leukemia: incidence, risk factors, and influence on outcome

BACKGROUND

Even after the introduction of all-trans retinoic acid (ATRA), early hemorrhagic death remains a major cause of remission induction failure for acute promyelocytic leukemia (APL).

METHODS

To investigate severe hemorrhagic complications during remission induction therapy with respect to incidence, risk factors, and influence on outcome. Results were analyzed for 279 patients enrolled in the APL97 study conducted by the Japan Adult Leukemia Study Group (JALSG).

RESULTS

Severe hemorrhage occurred in 18 patients (6.5%). Although most of them were receiving frequent transfusions, the targeted levels of platelet counts (30 x 10(9)/L) and plasma fibrinogen (1.5 g/L) for this study were reached at the day of bleeding in only 71% and 40%, respectively. Nine of them succumbed to an early death, while the remaining nine patients eventually achieved complete remission (CR). The 5-yr event-free survival rate was 68.1% for those who did not suffer severe hemorrhage, and 31.1% for those who did (P < 0.0001). For patients who achieved CR, on the other hand, there was no difference in disease-free survival between patients with and without severe hemorrhage (P = 0.6043). Risk factor analysis identified three pretreatment variables associated with severe hemorrhage: initial fibrinogen level, white blood cell count, and performance status. Additionally, patients with severe hemorrhage were more easily prone to develop retinoic acid syndrome or pneumonia than patients without hemorrhage.

CONCLUSIONS

These results indicate that fatal hemorrhage represents a major obstacle in curing APL, and that patients with such high-risk features may benefit from more aggressive supportive care.

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.

Role of histamine H3 and H4 receptors in mechanical hyperalgesia following peripheral nerve injury

OBJECTIVE

Histamine is a chemical mediator that acts at four known types of histamine receptors and has been widely implicated in the development of nociception and neuropathic pain. Blocking histamine H(1) and H(2) receptors has been shown to reduce hyperalgesia following nerve injury, but the role of histamine H(3) and H(4) receptors in neuropathic pain has not been studied. Here, we used blockers of histamine H(3) and H(4) receptors to assess their effects on neuropathic pain behavior and mast cell numbers following peripheral nerve injury. In addition, we assessed the effect of activating H(4) receptors on neuropathic pain behavior.

METHODS

Rats were subjected to a partial ligation of the sciatic nerve, a model of neuropathic pain, and were treated either systemically or locally (hindpaw) with the H(3)/H(4) receptor inverse agonist thioperamide, the specific H(4) receptor antagonist JNJ 7777120, or the H(4) receptor agonist VUF 8430. Measurements of mechanical hyperalgesia were carried out by Randall-Selitto test for 1-3 weeks, and sciatic nerve tissues were analyzed for numbers of intact mast cells by histology at 9 h after surgery.

RESULTS

Rats treated with thioperamide or JNJ 7777120 showed significantly enhanced mechanical hyperalgesia after partial ligation of the sciatic nerve. The number of intact mast cells in the injured nerve of these rats was higher than in control rats suggesting reduced mast cell degranulation, but was still significantly lower than in intact nerves. Rats treated with VUF 8430 showed significantly reduced mechanical hyperalgesia.

CONCLUSION

We propose that the increase in mechanical hyperalgesia produced by thioperamide and JNJ 7777120 and the decrease in mechanical hyperalgesia produced by VUF 8430 may represent a direct effect of these agents on mechanospecific primary afferents, or an indirect effect of these agents via injury-induced inflammation.

Treatment of solid tumors and metastases by fibrinogen-targeted anticancer drug therapy

The accumulation of fibrin/fibrinogen and other coagulation factors in and around solid tumors and metastatic foci has been recognized for a century as an aspect of cancer pathology. On this basis, anticoagulants and fibrinolytic agents have been deployed as adjuvant anticancer therapies, but they have proved clinically useful for only a small proportion of tumors and they only control the functions of the coagulant components. Overuse or long-term application of anticoagulants and fibrinolytic agents often lead to undesirable side-effects. Here, we propose that anticancer drugs that act by different mechanisms can inhibit tumor-associated coagulation, and it may be possible to develop drugs that specifically targeting tumor-related coagulation, have specific cytotoxic effects on tumor and metastatic cells. We provide laboratory and clinical evidence supporting the hypothesis and offer proposals for future applications.

Oncogenes, Trousseau Syndrome, and Cancer-Related Changes in the Coagulome of Mice and Humans

Cancer is often associated with venous thrombosis, a phenomenon that was first described by Trousseau in 1865 (Trousseau syndrome). Recent studies have begun to explain how oncogenic events may deregulate the hemostatic system. For instance, activated oncogenes (K-ras, EGFR, PML-RARalpha, and MET) or inactivated tumor suppressors (e.g., 53 or PTEN) may increase the risk of thrombosis by inducing the expression of tissue factor, a potent procoagulant molecule, and plasminogen activator inhibitor-1, a fibrinolysis inhibitor. In a more complex clinical reality, transforming genes may often act in concert with numerous epigenetic factors, including hypoxia, inflammation, anticancer therapy, contact between blood and metastatic cancer cells, and emission of procoagulant vesicles from tumors and their stroma into the circulation. To add to mechanistic insights gained from mouse models, which may not fully phenocopy human Trousseau syndrome, we suggest that valuable clues to progression and thrombosis risk may be obtained by monitoring multiple hemostatic variables in cancer patients ("coagulomics").

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.

Retinoic acid-induced CD38 antigen promotes leukemia cells attachment and interferon-gamma/interleukin-1beta-dependent apoptosis of endothelial cells: implications in the etiology of retinoic acid syndrome

All-trans retinoic acid (RA) treatment of patients with acute promyelocytic leukemia (APL) induces complete remission in more than 90% of the cases. Although RA therapy is well tolerated, about 25% of APL patients develop a potentially fatal condition called retinoic acid syndrome (RAS). Molecular mechanisms underlying the development of RAS pathogenesis, especially those that result in the damage of endothelial cells remain elusive. In the present study, we found that RA treatment induces the expression of interferon-gamma (IFN-gamma) and interleukin-1beta (IL-1beta) in peripheral blast cells from APL patients. IFN-gamma and IL-1beta also exerted synergistic effect in driving human umbilical cord endothelial cells (HUVECs) and human lung microvascular endothelial cells (HLMVECs) into apoptosis. RA also upregulated the expression of CD38, an ectoenzyme responsible for the generation of the calcium messenger cyclic ADP-ribose. Importantly, RA-induced CD38 expression promoted strong attachment of leukemia cells to endothelial cells, and incubation of endothelial cells with either high concentration (100 ng/ml) of IFN-gamma alone or low concentration of IL-1beta and IFN-gamma (10 ng/ml, each) induced strong apoptotic responses as revealed by caspase-8 activation and DNA fragmentation. Our results suggest that these RA-induced events could contribute to the development of RAS pathogenesis in patients with APL.

Sudden death due to undiagnosed acute promyelocytic leukemia: a case report

Acute promyelocytic leukemia (APL) is associated with severe hemorrhagic coagulopathy induced by the release of procoagulant, plasminogen, and protease from leukemic cells. The case described in this report is of a 15-year-old male who unexpectedly died due to a cerebral hemorrhage caused by underlying APL within 12 h after presentation. This case suggests that underlying APL should be considered as a differential diagnosis when sudden death occurs with a fatal spontaneous hemorrhage, although it is rare.

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

BACKGROUND

Thromboembolism can occur during acute leukemia, especially acute lymphoid leukemia (ALL) treated with L-asparaginase. Yet, most reports are anecdotical and scarce data are available on the risk of thrombosis in acute myeloid leukemia (AML).

OBJECTIVES

To evaluate the risk of thrombosis in patients with acute leukemia.

PATIENTS AND METHODS

Three-hundred and seventy-nine consecutive adult patients with newly diagnosed acute leukemia were recruited in an observational cohort study conducted from January 1994 to December 2003. Diagnosis was ALL in 69 patients, acute promyelocytic leukemia (APL; FAB subtype M3) in 31, and non-M3 AML in 279. All first or recurrent symptomatic thromboembolic events objectively diagnosed were recorded.

RESULTS

Twenty-four patients of the overall 379 (6.3%; 95% CI 4.1%-9.2%) had a first thrombosis, venous in 80% of the cases and arterial in 20%. At diagnosis, thrombosis was a presenting manifestation in 13 cases (3.4% of the whole cohort): 1.4% in ALL, 9.6% in APL, and 3.2% in non-M3 AML patients. Follow-up was carried out on 343 patients without thrombosis at diagnosis and further 11 thrombotic events (3.2%) were recorded. At 6 months from diagnosis, the cumulative incidence of thrombosis was 10.6% in ALL, 8.4% in APL, and 1.7% in non-M3 AML patients. The patients who received L-asparaginase had a 4.9-fold increased risk of thrombosis in comparison with those who did not (95% CI 1.5-16.0). The fatality rate due to thrombosis was 0.8%.

CONCLUSIONS

In patients with acute leukemia, the risk of thrombosis is not negligible. Thombosis can be a presenting symptom at diagnosis in a significant portion of cases with APL (9.6%) and non-M3 AML (3.2%); a similar rate of thrombosis can occur during the subsequent course of the disease. The incidence of symptomatic thrombosis at diagnosis is relatively low in ALL patients (1.4%), but is significantly increased by further treatment up to 10.6%. Strategies of antithrombotic prophylaxis should be investigated in this setting.

Personalized exposure assessment: promising approaches for human environmental health research

New technologies and methods for assessing human exposure to chemicals, dietary and lifestyle factors, infectious agents, and other stressors provide an opportunity to extend the range of human health investigations and advance our understanding of the relationship between environmental exposure and disease. An ad hoc Committee on Environmental Exposure Technology Development was convened to identify new technologies and methods for deriving personalized exposure measurements for application to environmental health studies. The committee identified a "toolbox" of methods for measuring external (environmental) and internal (biologic) exposure and assessing human behaviors that influence the likelihood of exposure to environmental agents. The methods use environmental sensors, geographic information systems, biologic sensors, toxicogenomics, and body burden (biologic) measurements. We discuss each of the methods in relation to current use in human health research; specific gaps in the development, validation, and application of the methods are highlighted. We also present a conceptual framework for moving these technologies into use and acceptance by the scientific community. The framework focuses on understanding complex human diseases using an integrated approach to exposure assessment to define particular exposure-disease relationships and the interaction of genetic and environmental factors in disease occurrence. Improved methods for exposure assessment will result in better means of monitoring and targeting intervention and prevention programs.