Haemostatic problems in acute promyelocytic leukaemia

Impaired fibrinolysis and increased clot strength are potential risk factors for thrombosis in lymphoma

Thrombosis and bleeding are significant contributors to morbidity and mortality in patients with hematological cancer, and the impact of altered fibrinolysis on bleeding and thrombosis risk is poorly understood. In this prospective cohort study, we investigated the dynamics of fibrinolysis in patients with hematological cancer. Fibrinolysis was investigated before treatment and 3 months after treatment initiation. A dynamic clot formation and lysis assay was performed beyond the measurement of plasminogen activator inhibitor 1, tissue- and urokinase-type plasminogen activators (tPA and uPA), plasmin-antiplasmin complexes (PAP), α-2-antiplasmin activity, and plasminogen activity. Clot initiation, clot propagation, and clot strength were assessed using rotational thromboelastometry. A total of 79 patients were enrolled. Patients with lymphoma displayed impaired fibrinolysis with prolonged 50% clot lysis time compared with healthy controls (P = .048). They also displayed decreased clot strength at follow-up compared with at diagnosis (P = .001). A patient with amyloid light-chain amyloidosis having overt bleeding at diagnosis displayed hyperfibrinolysis, indicated by a reduced 50% clot lysis time, α-2-antiplasmin activity, and plasminogen activity, and elevated tPA and uPA. A patient with acute promyelocytic leukemia also displayed marked hyperfibrinolysis with very high PAP, indicating extreme plasmin generation, and clot formation was not measurable, probably because of the extremely fast fibrinolysis. Fibrinolysis returned to normal after treatment in both patients. In conclusion, patients with lymphoma showed signs of impaired fibrinolysis and increased clot strength, whereas hyperfibrinolysis was seen in patients with acute promyelocytic leukemia and light-chain amyloidosis. Thus, investigating fibrinolysis in patients with hematological cancer could have diagnostic value.

Predictive factors for differentiating thrombohemorrhagic disorders in high-risk acute promyelocytic leukemia

INTRODUCTION

Acute promyelocytic leukemia (APL) is often accompanied by potentially fatal coagulopathy, especially in high-risk APL. Bleeding, particularly severe bleeding is the leading cause of early death (ED). Meanwhile, thrombosis, the other major coagulopathic complication, is being increasingly recognized. However, predictors of thrombohemorrhagic disorders are still not well investigated.

MATERIALS AND METHODS

In this study, we retrospectively studied 83 patients with high-risk APL and categorized them into severe bleeding, thrombosis and no evident events groups.

RESULTS

Severe bleeding was observed in 15 patients, nearly half of whom died of hemorrhage, while thrombosis was observed in 12 patients. Risk factor analysis showed that high WBC (>58.76 × 10⁹/L) (p = 0.001) and prolonged PT (>17.7 s) (p = 0.015) could be independent predictors for severe bleeding, while high WBC/D-dimer>5.12 (p = 0.002) and low D-dimer/FIB<5.14 (p = 0.03) could be independent predictors for thrombosis in high-risk APL patients. Moreover, there are significant differences in WBC/D-dimer and D-dimer/FIB between DIC and Non-DIC groups (p < 0.001). Notably, we found that the WBC/D-dimer was dramatically higher in the thrombotic group than in the other two groups at the time of admission or during the first week of induction therapy.

CONCLUSIONS

High WBC and prolonged PT could predict severe bleeding in high-risk APL patients, while high WBC/D-dimer and low D-dimer/FIB could be independent predictors for thrombosis. For high-risk APL, WBC/D-dimer and D-dimer/FIB are also beneficial in the diagnosis of DIC. WBC/D-dimer might help early identification of thrombosis at the time of admission or during the first week of induction therapy.

Disorders of Fibrinogen and Fibrinolysis

Fibrinogen plays a fundamental role in coagulation through its support for platelet aggregation and its conversion to fibrin. Fibrin stabilizes clots and serves as a scaffold and immune effector before being broken down by the fibrinolytic system. Given its importance, abnormalities in fibrin(ogen) and fibrinolysis result in a variety of disorders with hemorrhagic and thrombotic manifestations. This review summarizes (i) the basic elements of fibrin(ogen) and its role in coagulation and the fibrinolytic system; (ii) the laboratory evaluation for fibrin(ogen) disorders, including the use of global fibrinolysis assays; and (iii) the management of congenital and acquired disorders of fibrinogen and fibrinolysis.

Acute promyelocytic leukemia presenting as recurrent venous and arterial thrombotic events: a case report and review of the literature

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia characterized by a translocation of chromosomes 15 and 17, creating an alternation in the retinoic acid receptor-alpha (RAR-alpha) gene. This leads to excessive medullary production of promyelocytic blasts, which are frequently associated with the hemorrhagic complications seen in APL. In contrast, APL-associated thrombosis occurs much less frequently and is an underappreciated life-threatening manifestation of the disease. Most thrombotic events occur during induction chemotherapy with all-transretinoic acid and are rarely seen as the initial presentation on APL. Here we report an exceedingly rare case of a patient with recurrent venous and arterial thrombotic events, including deep vein thrombosis, bilateral segmental pulmonary embolism, an ischemic stroke, splenic infarcts, and renal infarcts, later found to have APL. We aim to discuss the most recent understanding of the pathogenesis of APL-associated thrombosis and to summarize the literature of this rare presentation of APL.

Annexin A2 in Fibrinolysis, Inflammation and Fibrosis

As a cell surface tissue plasminogen activator (tPA)-plasminogen receptor, the annexin A2 (A2) complex facilitates plasmin generation on the endothelial cell surface, and is an established regulator of hemostasis. Whereas A2 is overexpressed in hemorrhagic disease such as acute promyelocytic leukemia, its underexpression or impairment may result in thrombosis, as in antiphospholipid syndrome, venous thromboembolism, or atherosclerosis. Within immune response cells, A2 orchestrates membrane repair, vesicle fusion, and cytoskeletal organization, thus playing a critical role in inflammatory response and tissue injury. Dysregulation of A2 is evident in multiple human disorders, and may contribute to the pathogenesis of various inflammatory disorders. The fibrinolytic system, moreover, is central to wound healing through its ability to remodel the provisional matrix and promote angiogenesis. A2 dysfunction may also promote tissue fibrogenesis and end-organ fibrosis.

A Case of Acute Promyelocytic Leukemia With Retinal Hemorrhages Beneath Internal Limiting Membrane During Clinical Remission

Leukemia is a systematic cancer of the blood and blood-forming tissues that affects multiple organs. Acute myeloid leukemia (AML) is the most common type of leukemia that affects adults. Ophthalmic manifestations of leukemia could be observed in both acute and chronic leukemias. Around 35.4% of leukemia patients present with leukemic retinopathy. In this report, we discuss the case of a patient who was diagnosed with acute promyelocytic leukemia (APL) and went on to develop leukemic retinopathy during chemotherapy. A 35-year-old male was diagnosed with APL and received induction therapy with daunorubicin, and all-trans retinoic acid (ATRA) in a seven + three regimen. During the remission phase, he presented with a complaint of decreased vision of the right eye for about three weeks after the initiation of the therapy. On examination, the best-corrected visual acuity (BCVA) was found to be 6/60 in the right eye and 6/6 in the left eye. Fundus examination showed intraretinal hemorrhages in the posterior pole of both eyes. Fundus photography of the right eye showed resolved macular bleeding, temporal retinal bleeding, fresh inferonasal, and supraoptic retinal hemorrhage. For the left eye, however, it showed a small hemorrhagic spot temporal to the macula. Optical coherence tomography (OCT) was performed on both eyes, which showed sub-inner limiting membrane (sub-ILM) hemorrhage in the right macula with normal OCT of the left eye. There are multiple reported ocular manifestations of leukemic retinopathy including flame-shaped hemorrhage, cotton wool spots, and Roth spots. In patients with APL, thrombocytopenia and intracranial hemorrhage are the proposed underlying mechanism of retinal hemorrhage. Terson's syndrome, which is an intracranial hemorrhage with associated retinal hemorrhage, has been reported to occur during ATRA induction therapy. Sub-ILM hemorrhage is relatively uncommon, and it has been associated with multiple primary pathologies such as Valsalva retinopathy, Terson's syndrome, and bleeding dyscrasias. Retinal hemorrhage is a serious complication in leukemic patients; it could be the presenting complaint or even manifest after the initiation of therapy. Early detection and frequent follow-ups are crucial for its management.

Outcomes and Clinical Characteristics of Intracranial Hemorrhage in Patients with Hematologic Malignancies: A Systematic Literature Review

BACKGROUND

Many clinical and demographic factors can influence survival of patients with hematologic malignancies who have intracranial hemorrhages (ICHs). Understanding the influence of these factors on patient survival can guide treatment decisions and may inform prognostic discussions. We conducted a systematic literature review to determine survival of patients with intracranial hemorrhages and concomitant hematologic malignancy.

METHODS

A systematic literature review was conducted and followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. PubMed/MEDLINE, Web of Science, Ovid, SCOPUS, and Embase databases were queried with the following terms: ("intracranial hemorrhages" OR "brain hemorrhage" OR "cerebral hemorrhage" OR "subdural hematoma" OR "epidural hematoma" OR "intraparenchymal hemorrhage") AND ("Hematologic Neoplasms" OR "Myeloproliferative Disorders" OR "Myelofibrosis" OR "Essential thrombocythemia" OR "Leukemia"). Abstracts and articles were screened according to inclusion and exclusion criteria that were determined a priori.

RESULTS

Literature review yielded 975 abstracts from which a total of 68 full-text articles were reviewed. Twelve articles capturing 634 unique patients were included in the final qualitative analysis. Median overall survival for all patients ranged from 20 days to 1.5 months while median overall survival for the subset of patients having ICH within 10 days of diagnosis of hematologic malignancy was 5 days. Intraparenchymal hemorrhages, multiple foci of hemorrhage, transfusion-resistant low platelet counts, leukocytosis, low Glasgow Coma Scale scores at presentation, and ICH early in treatment course were associated with worse outcomes.

CONCLUSIONS

Survival for patients with hematologic malignancies and concomitant ICHs remains poor. Early detection, recognition of poor prognostic factors, and correction of hematologic abnormalities essential to prevention and treatment of ICHs in this patient population.

Successful treatment of disseminated intravascular coagulation by recombinant human soluble thrombomodulin in patients with acute myeloid leukemia

Disseminated intravascular coagulation (DIC) is a life-threatening condition that frequently occurs in patients with hematologic malignancies. Currently, recombinant human soluble thrombomodulin (rTM) is a therapeutic DIC drug that is manufactured and sold in Japan only. We evaluated the efficacy of rTM compared to that of gabexate mesilate (GM), which was previously used routinely for treating DIC in Japan, in patients with acute myeloid leukemia (AML). This retrospective study enrolled 43 AML patients, including 17 with acute promyelocytic leukemia (APL), that was complicated with DIC. DIC resolution rates in non-APL AML and rTM-treated APL patients were 68.4% and 81.8%, respectively. In non-APL AML patients, the duration of rTM administration was significantly shorter than that of GM (7 vs 11 days), suggesting that rTM could improve DIC earlier than GM, although rTM was used in patients with more severe DIC. Moreover, treatment with rTM significantly improved DIC score, fibrinogen, fibrin/fibrinogen degradation product (FDP), and prothrombin time (PT) ratio. Conversely, treatment with GM only improved the DIC score and FDP. In APL patients, the duration of rTM administration was also significantly shorter than that of GM. No severe side effects associated with the progression of bleeding were observed during rTM administration. These findings suggest that rTM is safe, and its anti-DIC effects are more prompt than GM for treating AML patients with DIC.

Severe Intracranial Hemorrhage at Initial Presentation of Acute Myelogenous Leukemia

Intracranial hemorrhage (ICH) is the second leading cause of mortality among patients diagnosed with acute myelogenous leukemia (AML). The bone marrow failure associated with AML produces dysfunctional platelets, which significantly increases the risk of hemorrhagic complications within this population. In this report we discuss the case of a previously healthy female patient, newly diagnosed with AML, who rapidly developed fatal ICH.

How I treat disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a condition characterized by systemic activation of coagulation, potentially leading to thrombotic obstruction of small and midsize vessels, thereby contributing to organ dysfunction. At the same time, ongoing consumption of platelets and coagulation proteins results in thrombocytopenia and low concentrations of clotting factors, which may cause profuse hemorrhagic complications. DIC is always secondary to an underlying condition, such as severe infections, solid or hematologic malignancies, trauma, or obstetric calamities. A reliable diagnosis of DIC can be made through simple scoring algorithms based on readily available routine hemostatic parameters. The cornerstone of supportive treatment of this coagulopathy is management of the underlying condition. Additionally, administration of heparin may be useful, and restoration of physiological anticoagulants has been suggested, but has not been proven successful in improving clinically relevant outcomes so far. In patients with major bleeding or at risk for hemorrhagic complications, administration of platelet concentrates, plasma, or coagulation factor concentrates should be considered.

Disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is an acquired syndrome characterized by widespread intravascular activation of coagulation that can be caused by infectious insults (such as sepsis) and non-infectious insults (such as trauma). The main pathophysiological mechanisms of DIC are inflammatory cytokine-initiated activation of tissue factor-dependent coagulation, insufficient control of anticoagulant pathways and plasminogen activator inhibitor 1-mediated suppression of fibrinolysis. Together, these changes give rise to endothelial dysfunction and microvascular thrombosis, which can cause organ dysfunction and seriously affect patient prognosis. Recent observations have pointed to an important role for extracellular DNA and DNA-binding proteins, such as histones, in the pathogenesis of DIC. The International Society on Thrombosis and Haemostasis (ISTH) established a DIC diagnostic scoring system consisting of global haemostatic test parameters. This scoring system has now been well validated in diverse clinical settings. The theoretical cornerstone of DIC management is the specific and vigorous treatment of the underlying conditions, and DIC should be simultaneously managed to improve patient outcomes. The ISTH guidance for the treatment of DIC recommends treatment strategies that are based on current evidence. In this Primer, we provide an updated overview of the pathophysiology, diagnosis and management of DIC and discuss the future directions of basic and clinical research in this field.

Transient ischemic attack as an unusual initial manifestation of acute promyelocytic leukemia

Patients with acute promyelocytic leukemia (APL) are prone to both bleeding and thrombosis. Both of these have a significant impact on the morbidity and mortality of patients with this disease. Here we report a case of a 41-year-old male, who presented with transient ischemic attack (TIA) and early neurological deterioration (END) as initial manifestations prior to an ultimate diagnosis of APL. This patient had no cerebrovascular risk factors or familial cerebrovascular disease. The patient experienced an acute ischemic stroke, verified by magnetic resonance imaging (MRI), in less than 24 h after his second hospital admission. Some APL patients suffer from cerebral ischemia as an initial manifestation or during induction therapy, and patients presenting this condition may continue to deteriorate until their death during hospitalization. Thus, APL should be considered as a possible underlying disease in patients with TIA without cerebrovascular risk factors. Delayed diagnosis and treatment of APL can be fatal.

PML-RARa modulates the vascular signature of extracellular vesicles released by acute promyelocytic leukemia cells

Oncogenic transformation is believed to impact the vascular phenotype and microenvironment in cancer, at least in part, through mechanisms involving extracellular vesicles (EVs). We explored these questions in the context of acute promyelocytic leukemia cells (NB4) expressing oncogenic fusion protein, PML-RARa and exquisitely sensitive to its clinically used antagonist, the all-trans retinoic acid (ATRA). We report that NB4 cells produce considerable numbers of EVs, which are readily taken up by cultured endothelial cells triggering their increased survival. NB4 EVs contain PML-RARa transcript, but no detectable protein, which is also absent in endothelial cells upon the vesicle uptake, thereby precluding an active intercellular trafficking of this oncogene in this setting. ATRA treatment changes the emission profile of NB4-related EVs resulting in preponderance of smaller vesicles, an effect that occurs in parallel with the onset of cellular differentiation. ATRA also increases IL-8 mRNA and protein content in NB4 cells and their EVs, while decreasing the levels of VEGF and tissue factor (TF). Endothelial cell uptake of NB4-derived EVs renders these cells more TF-positive and procoagulant, and this effect is diminished by pre-treatment of EV donor cells with ATRA. Profiling angiogenesis-related transcripts in intact and ATRA-treated APL cells and their EVs reveals multiple differences attributable to cellular responses and EV molecular packaging. These observations point to the potential significance of changes in the angiogenic signature and activity associated with EVs released from tumor cells subjected to targeted therapy.

Thrombomodulin alfa treatment in patients with acute promyelocytic leukemia and disseminated intravascular coagulation: a retrospective analysis of an open-label, multicenter, post-marketing surveillance study cohort

INTRODUCTION

Patients with acute promyelocytic leukemia (APL) can develop disseminated intravascular coagulation (DIC) that results in life-threatening hemorrhagic complications. Studies regarding the safety and efficacy of thrombomodulin alfa (TM-α; recombinant human soluble thrombomodulin) in patients with APL and DIC are limited.

MATERIALS AND METHODS

A retrospective evaluation was performed on a cohort of 172 patients with APL from an open-label, multicenter, post-marketing surveillance study of TM-α.

RESULTS

Of the 172 patients, 31 were relapse/refractory APL patients, and 141 were newly diagnosed APL patients. Within the first 30 days, 24 patients (14.0%) died, and six of those deaths (3.5%) were due to hemorrhage. In total, 12 patients (7.0%) had severe hemorrhagic complications. Both the early death rate due to hemorrhage as well as the severe hemorrhage rate did not exceed those in some recent population-based studies of patients with APL. Forty-nine patients received TM-α prior to the initiation of antileukemic treatment, and one patient experienced hemorrhagic early death (ED), suggesting that early TM-α treatment appeared to result in a reduction in the hemorrhagic ED rate. Moreover, TM-α improved coagulopathy regardless of concomitant all-trans retinoic acid treatment.

CONCLUSIONS

This study confirmed the safety and efficacy of TM-α in daily clinical practice for patients with APL and DIC. TM-α appeared to reduce hemorrhagic early deaths due to DIC in patients with APL who were receiving antileukemic treatment.

Post-marketing surveillance of thrombomodulin alfa, a novel treatment of disseminated intravascular coagulation - safety and efficacy in 1,032 patients with hematologic malignancy

INTRODUCTION

Post-marketing surveillance of thrombomodulin alfa (TM-α) was performed to evaluate safety and efficacy in patients with disseminated intravascular coagulation (DIC) with hematologic malignancy.

MATERIALS AND METHODS

All patients treated with TM-α from May 2008 to April 2010 in Japan were included. Information about baseline characteristics, safety, and efficacy were collected. The DIC resolution rate, survival rate on Day 28 after the last TM-α administration, and changes in DIC score and coagulation tests were evaluated.

RESULTS

The underlying diseases associated with DIC were acute myeloid leukemia (except for acute promyelocytic leukemia, n=350), lymphoma (n=199), acute promyelocytic leukemia (n=172), acute lymphoblastic leukemia (n=156), myelodysplastic syndromes (n=61), and other (n=94). The incidence rates of bleeding-related adverse events and adverse drug reactions were 17.8% and 4.6%, respectively. In subjects with bleeding symptoms at baseline, 55.0% were assessed as disappeared or improved based on symptoms after TM-α treatment. The DIC resolution and survival rates were 55.9% and 70.7%, respectively. The DIC score and coagulation tests including thrombin-antithrombin complex (TAT) were significantly improved. Coagulation tests were significantly improved after TM-α treatment even in subjects whose clinical course of underlying disease was assessed as unchanged or exacerbated.

CONCLUSIONS

This surveillance confirmed the safety and efficacy of TM-α in clinical practice, thus TM-α may be an ideal treatment for patients with DIC based upon hematologic malignancy.

Pathogenesis and treatment of thrombohemorrhagic diathesis in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a distinct subtype of myeloid leukemia characterized by t(15;17) chromosomal translocation, which involves the retinoic acid receptor-alpha (RAR-alpha). APL typically presents with a life-threatening hemorrhagic diathesis. Before the introduction of all-trans retinoic acid (ATRA) for the cure of APL, fatal hemorrhages due, at least in part, to the APL-associated coagulopathy, were a major cause of induction remission failure. The laboratory abnormalities of blood coagulation found in these patients indicate the occurrence of a hypercoagulable state. Major determinants of the coagulopathy of APL are endogenous factors expressed by the leukemic cells, including procoagulant factors, fibrinolytic proteins, and non-specific proteolytic enzymes. In addition, these cells have an increased capacity to adhere to the vascular endothelium, and to secrete inflammatory cytokines [i.e. interleukin-1beta (IL-1beta) and tumor necrosis factor (TNF-alpha)], which in turn stimulate the expression of prothrombotic activities by endothelial cells and leukocytes. ATRA can interfere with each of the principal hemostatic properties of the leukemic cell, thus reducing the APL cell procoagulant potential, in parallel to the induction of cellular differentiation. This effect occurs in vivo, in the bone marrow of APL patients receiving ATRA, and is associated with the improvement of the bleeding symptoms. Therapy with arsenic trioxide (ATO) also beneficially affects coagulation in APL. However, early deaths from bleeding still remain a major problem in APL and further research is required in this field. In this review, we will summarize our current knowledge of the pathogenesis of the APL-associated coagulopathy and will overview the therapeutic approaches for the management of this complication.

The role of the annexin A2 heterotetramer in vascular fibrinolysis

The vascular endothelial cells line the inner surface of blood vessels and function to maintain blood fluidity by producing the protease plasmin that removes blood clots from the vasculature, a process called fibrinolysis. Plasminogen receptors play a central role in the regulation of plasmin activity. The protein complex annexin A2 heterotetramer (AIIt) is an important plasminogen receptor at the surface of the endothelial cell. AIIt is composed of 2 molecules of annexin A2 (ANXA2) bound together by a dimer of the protein S100A10. Recent work performed by our laboratory allowed us to clarify the specific roles played by ANXA2 and S100A10 subunits within the AIIt complex, which has been the subject of debate for many years. The ANXA2 subunit of AIIt functions to stabilize and anchor S100A10 to the plasma membrane, whereas the S100A10 subunit initiates the fibrinolytic cascade by colocalizing with the urokinase type plasminogen activator and receptor complex and also providing a common binding site for both tissue-type plasminogen activator and plasminogen via its C-terminal lysine residue. The AIIt mediated colocalization of the plasminogen activators with plasminogen results in the rapid and localized generation of plasmin to the endothelial cell surface, thereby regulating fibrinolysis.

The annexin A2 system and vascular homeostasis

Optimal fibrin balance requires precisely controlled plasmin generation on the surface of endothelial cells, which line the blood vessel wall. As a co-receptor for plasminogen and tissue plasminogen activator (tPA), which are key factors in plasmin generation, the annexin A2 (A2) complex promotes vascular fibrinolysis. The intracellular A2 complex is a heterotetramer of two A2 monomers and two copies of the associated protein, p11. In response to endothelial cell activation, A2 is phosphorylated by src-kinase, and translocated to the cell surface in a highly regulated manner. Over-expression of A2 is seen in acute promyelocytic leukemia during the early hemorrhagic phase, while high titer antibodies to A2, as in antiphospholipid syndrome or cerebral venous thrombosis, are associated with thrombosis. In experimental hyperhomocysteinemia, moreover, derivatization of A2 by homocysteine leads to intravascular fibrin accumulation and dysangiogenesis, features that phenocopy the Anxa2(-/-) mouse. Exogenous A2 may also offer a novel therapeutic approach to ischemic thrombotic stroke, as administration of A2 in conjunction with conventional tPA-based thrombolytic therapy improved outcome in an animal model. Here, we discuss the role of the A2 system in vascular homeostasis, the molecular interactions that regulate its profibrinolytic activity, and its potential role in the pathogenesis and treatment of vascular disease.

Management of acquired bleeding problems in cancer patients

Cancer patients can have acquired bleeding problems for many reasons. In this review, an approach to the evaluation and management of the bleeding patient is discussed. Specific issues including coagulation defects, thrombocytopenia, platelet dysfunction, and bleeding complications of specific hematological malignancies due to anticoagulation, are discussed.

PML/RARalpha fusion protein transactivates the tissue factor promoter through a GAGC-containing element without direct DNA association

A severe coagulopathy is a life-threatening complication of acute promyelocytic leukemia (APL) and is ascribable mainly to the excessive levels of tissue factor (TF) in APL cells regulated in response to the promyelocytic leukemia/retinoic acid receptor alpha (PML/RARalpha) fusion protein. The underlying molecular mechanisms for this regulation remain ill-defined. With U937-PR9 cell lines stably expressing luciferase reporter gene under the control of different mutants of the TF promoter, both luciferase and ChIP data allowed the localization of the PML/RARalpha-responsive sequence in a previously undefined region of the TF promoter at position -230 to -242 devoid of known mammalian transcription factor binding sites. Within this sequence a GAGC motif (-235 to -238) was shown to be crucial because deletion or mutation of these nucleotides impaired both PML/RARalpha interaction and promoter transactivation. However, EMSA results showed that PML/RARalpha did not bind to DNA probes encompassing the -230 to -242 sequences, precluding a direct DNA association. Mutational experiments further suggest that the activator protein 1 (AP-1) sites of the TF promoter are dispensable for PML/RARalpha regulation. This study shows that PML/RARalpha transactivates the TF promoter through an indirect interaction with an element composed of a GAGC motif and the flanking nucleotides, independent of AP-1 binding.

Management of acquired bleeding problems in cancer patients

Cancer patients can have acquired bleeding problems for many reasons. In this review, an approach to the bleeding patient in the Emergency Department is discussed. Specific issue including coagulation defects, thrombocytopenia, platelet dysfunction, bleeding complications of specific hematological malignancies and due to anticoagulation, are discussed.

Prediction of fatal intracranial hemorrhage in patients with acute myeloid leukemia

BACKGROUND

Intracranial hemorrhage (ICH) is the second leading cause of mortality in patients with acute myeloid leukemia (AML). However, the prognostic factors for ICH in AML patients are still under investigation.

PATIENTS AND METHODS

A total of 841 AML patients admitted to the Department of Internal Medicine from January 1995 to December 2007 were enrolled in this study.

RESULTS

There were 51 patients with ICH, median age of 51 (range 17-86), including 12 patients diagnosed as acute promyelocytic leukemia. Forty-three patients were refractory/relapsed status. ICH was localized in the supratentorium (44 cases), basal ganglion (9), cerebellum (5), and brainstem (4). Twenty-one patients had multiple sites. Thirty-eight patients had intraparenchymal hemorrhage, 16 subarachnoid hemorrhage (SAH), 10 subdural hemorrhage, and one epidural hemorrhage (EDH). Hemorrhage ruptured into the ventricles in 13 patients. Thirty-four patients (67%) died of ICH within 30 days of diagnosis. Multivariate analysis revealed four independent prognostic factors, prolonged prothrombin time international normalized ratio >1.5 (P < 0.001), brainstem hemorrhage (P = 0.001), SAH (P = 0.017), and EDH (P = 0.014). Other clinico-laboratory data had no impact on 30-day survival.

CONCLUSIONS

ICH has high morbidity and mortality in AML. Early detection and aggressive correction coagulopathy may prevent the catastrophic event. Prompt image study for locations and types of ICH can predict outcomes.

A coagulation factor becomes useful in the study of acute leukemias: studies with blood coagulation factor XIII

The intracellular form of the coagulation factor XIII has previously been identified by immunomorphological techniques using polyclonal antibodies. In these studies, only the A subunit (FXIII-A) was detectable in megakaryocytes/platelets and in monocytes/macrophages. We developed several novel monoclonal antibody clones directed to both subunits (FXIII-A and FXIII-B) and investigated their appearance in normal and leukemic cells. By using 3- and 4-color flow cytometry FXIII expression was investigated in normal peripheral blood and bone marrow samples and in acute myeloblastic (AML) and lymphoblastic (ALL) leukemia cases. Samples were studied by Western blotting and confocal laser scanning microscopy. With a previously published ELISA assay applying two monoclonal antibodies directed to different epitopes in FXIII-A, we were able to measure the intracytoplasmic content of FXIII-A in normal cells and leukemic blasts. FXIII-A was detectable in normal peripheral blood monocytes and in large quantities in platelets, but both cell types were negative for FXIII-B. There was no surface staining for FXIII-A, it only appeared intracellularly. In samples derived from patients with AML M4 and M5, FXIII-A sensitively identified blast cells. Although normal lymphocytes do not express FXIII-A, 40% of ALL cases showed significant FXIII-A expression as determined by flow cytometry. FXIII-A positivity of lymphoblasts was verified by Western blotting, ELISA, and confocal laser scanning microscopy cytometry. These data provide evidence that FXIII-A is a sufficiently sensitive marker in differentiating myeloblasts and monoblasts and is suitable for identifying leukemia-associated phenotypes in ALL.

Platelet Transfusion Therapy

This article provides guidelines for the appropriate use of platelet transfusions to reduce unnecessary transfusions, thereby avoiding transfusion-related risks to the patients and the costs of platelet therapy. Platelet products available for transfusion are whole blood derived platelet concentrates and apheresis platelets. Leukoreduced platelets can be used to reduce platelet alloimmunization, cytomegalovirus transmission, and febrile transfusion reactions, while gamma irradiation prevents transfusion-associated graftversus-host disease. Other topics discussed are the expected response to transfused platelets and reasons for poor responses related to alloimmunization, underlying disease state, clinical conditions, and drugs. Appropriate transfusion guidelines based on pretransfusion platelet count, platelet dose, and whether the transfusion is prophylactic or therapeutic are outlined. Identification, prevention, and management of adverse consequences of platelet transfusions and platelet refractoriness are discussed.