Hydroxyurea for patients with essential thrombocythemia and a high risk of thrombosis

Life expectancy and prognostic factors in the classic BCR/ABL-negative myeloproliferative disorders

Among the 'classic' BCR/ABL-negative chronic myeloproliferative disorders, primary myelofibrosis (PMF) is associated with a substantial life-expectancy reduction. In this disease, initial haemoglobin level is the most important prognostic factor, whereas age, constitutional symptoms, low or high leukocyte counts, blood blast cells and cytogenetic abnormalities are also of value. Several prognostic systems have been proposed to identify subgroups of patients with a different risk, which is especially important in younger individuals, who may benefit from therapies with curative potential. Essential thrombocythaemia (ET) affects the patients' quality of life more than the survival, due to the high occurrence of thrombosis, whereas polycythaemia vera (PV) has a substantial morbidity derived from thrombosis but also a certain reduction in life expectancy. Therefore, in the latter disorders, prognostic studies have focused primarily on prediction of the thrombosis, with age and a previous history of thrombosis being the main prognostic factors of such complication. The importance of higher leukocyte counts in thrombosis development has been recently pointed out in ET and PV, where a role for mutated JAK2 allele burden has also been noted. With regard to PMF, the possible association of the mutation with shorter survival and higher acute transformation rate is currently being evaluated.

Essential thrombocythemia in a child with elevated thrombopoietin concentrations and skeletal anomalies

Essential thrombocythemia is a rare myleoproliferative disorder in pediatrics. This myleoproliferative disorder is characterized by excessive proliferation of megakaryocytes and sustained elevation of platelet count. Reactive thrombocytosis is a more common cause of elevated platelet counts among children. We describe a 2-year-old child with essential thrombocythemia, skeletal anomalies, and elevated thrombopoietin concentrations. The child's mother was also subsequently diagnosed with essential thrombocythemia and had elevated thrombopoietin concentrations. Chromosomal studies on the mother, child and other family members were normal.

JAK2 mutations and clinical practice in myeloproliferative neoplasms

With the discovery in the last 3 years of novel Janus kinase 2 (JAK2) and thrombopoietin receptor (MPL) mutations, the pathogenetic understanding of and clinical practice for myeloproliferative neoplasms (MPNs) have entered a new era. Each one of these newly discovered mutations, including JAK2V617F, MPLW515L, and a JAK2 exon 12 mutation, has been shown to result in constitutive activation of JAK-STAT signaling and also induce a MPN phenotype in mice. Thus, JAK2 is now considered to be a legitimate target for drug development in MPNs, and small molecule JAK2 inhibitors have already gone through successful preclinical testing, and early-phase human trials in primary myelofibrosis have already begun. Furthermore, JAK2 mutation screening has now become a front-line diagnostic test in the evaluation of both "erythrocytosis" and thrombocytosis and the 2001 World Health Organization diagnostic criteria for polycythemia vera, essential thrombocythemia, and primary myelofibrosis have now been revised to incorporate JAK2V617F mutation screening.

20+ yr without leukemic or fibrotic transformation in essential thrombocythemia or polycythemia vera: predictors at diagnosis

OBJECTIVES

The current study identified patients with either essential thrombocythemia (ET) or polycythemia vera (PV) who have survived for at least 20 yr without the development of either acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) or myelofibrosis (MF) and compared their presenting features with those in whom these complications occurred in the first 10 yr of disease.

METHODS

The study patients were selected from an institutional database of 1061 patients with either ET (n = 603) or PV (n = 458). In both instances, three distinct groups were delineated and their presenting features compared; group A included patients who have remained AML/MDS/MF free after a minimum follow-up of 20 yr; groups B and C included patients who developed either AML/MDS or MF, respectively, in the first decade of their disease.

RESULTS

The respective number of patients who fulfilled the above-mentioned criteria for inclusion in groups A, B and C were 40, 12 and 8 for ET and 23, 18 and 12 for PV. In ET, compared with both groups B and C, group A displayed significantly fewer patients with less than normal hemoglobin level (P < 0.0001 and =0.02) or male sex (P = 0.005 and 0.05), respectively. On multivariable analysis, only anemia sustained its significance. A similar analysis in PV revealed an association between group B and leukocytosis using a leukocyte count threshold of either 10 or 15 x 10(9)/L (P = 0.02).

CONCLUSION

The current study identifies PV patients with leukocytosis and ET patients with anemia as the most likely to undergo leukemic or fibrotic transformation.

Decreased transfusion needs associated with hydroxyurea therapy in Algerian patients with thalassemia major or intermedia

BACKGROUND

Studies of evolution of transfusion requirements in thalassemic patients treated with hydroxyurea have produced somewhat conflicting results, especially in patients with thalassemia major. Our aims were to determine the proportion of good responders to hydroxyurea in a population of transfusion-dependent thalassemic patients and to identify the factors associated with a decrease of transfusion needs.

STUDY DESIGN AND METHODS

Hydroxyurea treatment was initiated in 9 patients with thalassemia intermedia (TI) and 45 with thalassemia major (TM). Patients received transfusions when their hemoglobin (Hb) levels dropped below 6 g per dL. A decrease in annual transfusion requirements greater than 70 percent defined a good response, between 40 and 70 percent a partial response, and smaller than 40 percent no response.

RESULTS

The response was good in 8 (90%) patients with TI and 20 (44.5%) with TM, partial in 9 (20%) patients with TM, and absent in 1 (10%) with TI and 16 (35.5%) with TM. In TM patients, transfusion needs decreased by 56 percent over the first year of hydroxyurea treatment. By univariate analysis, a better response to hydroxyurea was associated with older age at the first transfusion (p = 0.02), higher prehydroxyurea Hb (p = 0.0004), codon 6(-A) mutation (p = 0.002), TI (p = 0.03), and history of splenectomy (p = 0.05). Xmn1-/- was associated with a worse response (p = 0.0001). By multivariate analysis, a better response was associated with the Xmn1 polymorphism (p = 0.008).

CONCLUSION

Hydroxyurea may be an alternative to transfusions for TI patients as well as for TM patients in countries that have limited blood supplies.

Analysis of risk factors predicting thrombotic and/or haemorrhagic complications in 306 patients with essential thrombocythemia

Thrombotic and haemorrhagic complications are the main causes of morbidity in Essential Thrombocythemia (ET). We investigated the clinical and laboratory characteristics associated with the occurrence of these events with the aim of identifying subgroups of patients who might benefit from anti-aggregant and/or cytoreductive therapy. The study involved 306 consecutive ET patients (median age 58 years and median follow-up 96 months); the investigated variables were age, gender, platelet count, previous history of thrombotic or haemorrhagic events, disease duration and cardiovascular risk factors. Forty-six patients (15%) experienced thrombotic complications during the follow-up: 26/64 patients with a previous history of thrombosis (40.6%) and 20/242 patients without (8.3%; p < 0.0001). Thirty-one patients (10%) experienced major haemorrhagic complications, mainly gastrointestinal tract bleeding: 3 with and 28 without a history of haemorrhagic events (p = 0.052). When the patients with a negative history of thrombosis were stratified on the basis of the number of cardiovascular risk factors (none vs. one vs. more than one), there was a significant correlation with the occurrence of thrombotic events (p < 0.05). ET patients with a positive history of thrombosis are at high risk of thrombotic complications, and should receive cytoreductive and anti-aggregant treatment. Asymptomatic patients with a negative thrombotic history and no cardiovascular risk factors are at low risk, and should not be treated. Patients with a negative thrombotic history and one or more cardiovascular risk factors are at intermediate risk, and should be treated with anti-aggregant and/or cytoreductive therapy. The need for treatment should be periodically re-evaluated. Age and platelet count, generally accepted as very important risk factors for thrombosis, did not seem in our series associated with an increased risk for thrombosis.

The history of myeloproliferative disorders: before and after Dameshek

In 1951, William Dameshek described the concept of 'myeloproliferative disorders (MPDs)' by grouping together chronic myelogenous leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) and erythroleukemia; he reasoned that a self-perpetuating trilineage myeloproliferation underlined their pathogenesis. Pre-Dameshek luminaries who laid the foundation for this unifying concept include Bennett, Virchow, Heuck, Vaquez, Osler, Di Guglielmo and Epstein. In 1960, Nowell and Hungerford discovered the Philadelphia (Ph) chromosome in CML. In 1967, Fialkow and colleagues used X-linked polymorphisms to establish CML as a clonal stem cell disease. Also in 1967, the PV Study Group was summoned by Louis Wasserman to study the natural history of PV and conduct large-scale clinical trials. In 1972, Janet Rowley deciphered the Ph chromosome as a reciprocal translocation between chromosomes 9 and 22, thus paving the way for its subsequent characterization as an oncogenic BCR-ABL mutation. In 1996, Brian Druker discovered imatinib-a small molecule ABL inhibitor with exceptional therapeutic activity in CML. In 2005, a gain-of-function JAK2 mutation (JAK2V617F) was described in BCR-ABL-negative MPDs, raising the prospect of a CML-like treatment strategy in PV, ET and PMF. The current review considers these and other landmark events in the history of MPDs.

Digital ischemia due to essential thrombocythemia: a case report

This report describes the case of a 34-year-old patient with essential thrombocythemia who presented with Raynaud's syndrome, was refractory to medical treatment, and developed progressive digital gangrene.

A review of the therapeutic agents used in the management of polycythaemia vera

The acquired clonal disorder Polycythaemia Vera leads to increased erythropoiesis, myelopoiesis and megakaryopoeisis. These anomalies result in an increased incidence of thromboembolic events, transformation to acute leukaemia and myelofibrosis. Treatments which aim to reduce the event rate may increase anaemia but may also affect the rate of complications. This paper reviews the evidence for the treatments which have been used in the management of the disorders over a 50 plus year period. Assessment of this evidence and its limitations form the basis for the current suggested management plans.

A phase I study of the novel ribonucleotide reductase inhibitor 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP, Triapine) in combination with the nucleoside analog fludarabine for patients with refractory acute leukemias and aggressive myeloproliferative disorders

Triapine is a potent ribonucleotide reductase (RR) inhibitor that depletes intracellular deoxyribonculeotide pools, especially dATP. We designed a Phase I trial of Triapine followed by the adenosine analog fludarabine in adults with refractory acute leukemias and aggressive myeloproliferative disorders (MPD). Two schedules were examined: (A) Triapine 105 mg/m(2)/day over 4 h followed by fludarabine daily x 5 (24 patients, fludarabine 15-30 mg/m(2)/dose); (B) Triapine 200 mg/m(2) over 24h followed by 5 days of fludarabine 30 mg/m(2)/day (9 patients). Complete and partial responses (CR, PR) occurred in Schedule A (5/24, 21%), with CR occurring at the 2 highest fludarabine doses (2/12, 17%). In contrast, no CR or PR occurred in Schedule B. Four of the 5 responses occurred in patients with underlying MPD (4/14, 29%). Drug-related toxicities included fever and metabolic acidosis. Triapine 105 mg/m(2) followed by fludarabine 30 mg/m2 daily x 5 is active in refractory myeloid malignancies and warrants continuing study for patients with aggressive MPD.

Classification of Ph-Negative Chronic Myeloproliferative Disorders – Morphology as the Yardstick of Classification

OBJECTIVE

Histopathology of bone marrow (BM) biopsies plays a crucial role in the interdisciplinary approach to diagnosis and classification of Ph-negative chronic myeloproliferative disorders. Based on careful clinicopathologic studies, BM features are critical determinants that help to predict overall prognosis, to detect complications such as progression to myelofibrosis and blast crisis, and to assess therapy-related changes.

METHODS AND RESULTS

A systematic evaluation of BM histopathology allows an objective identification of cases of (true) essential thrombocythemia and their separation from early prefibrotic stages of chronic idiopathic myelofibrosis. By follow-up examinations that include BM biopsies, the progression of the disease process is unveiled, which is especially important for patients with initial polycythemia vera and prefibrotic chronic idiopathic myelofibrosis that may require a different therapeutic approach than the full-blown stages.

CONCLUSION

BM biopsy should be considered as major diagnostic tool for evaluation and follow-up of patients enrolled in prospective studies.

Thrombose veineuse cérébrale secondaire à une thrombocytémie essentielle

INTRODUCTION

Essential thrombocythemia (ET) is a myeloproliferative syndrome; cerebral venous thrombosis (CVT) is a rare complication.

OBSERVATION

We report the case of a 20-year-old woman with an uneventful history who was admitted with intracranial hypertension syndrome which had developed over the last four months in association with bilateral decline of visual acuity. Physical examination at admission revealed stage II papilloedema and absence of any focal neurological signs. The brain MRI and the venous MRA showed a thrombosis involving the superior longitudinal sinus and the lateral sinus. The etiological analysis disclosed essential thrombocythemia (ET). The patient was given an antiedema and anticoagulant treatment. Later, an etiological cytoreductive therapy was initiated. Signs of intracranial hypertension regressed progressively with persistence of acute visual disorders associated with sequelar optical atrophy. Discussion. ET is a rare cause of CVT. Reports in the literature have discussed the mechanisms, the physiology, the therapeutic modalities and the clinical course of these CVTs secondarily to ET.

CONCLUSION

Stroke, especially transient ischemic attack, is the usual thrombotic expression of myeloproliferative syndrome. CVT is much more exceptional.

Essential thrombocythemia in young individuals: frequency and risk factors for vascular events and evolution to myelofibrosis in 126 patients

The frequency of vascular events and evolution to myelofibrosis (MF) in young individuals with essential thrombocythemia (ET) is not well known. The incidence and predisposing factors to such complications was studied in 126 subjects diagnosed with ET at a median age of 31 years (range: 5-40). Overall survival and probability of survival free of thrombosis, bleeding and MF were analyzed by the Kaplan-Meier method and the presence of the Janus Kinase 2 (JAK2) V617F mutation correlated with the appearance of such complications. The JAK2 mutation (present in 43% of patients) was associated with higher hemoglobin (Hb) (P<0.001) and lower platelets at diagnosis. With a median follow-up of 10 years (range: 4-25), 31 thrombotic events were registered (incidence rate: 2.2 thromboses/100 patients/year). When compared with the general population, young ET patients showed a significant increase in stroke (odds ratio 50, 95% CI: 21.5-115) and venous thromboses (odds ratio 5.3, 95% CI: 3.9-10.6). Thrombosis-free survival was 84% at 10 years, with tobacco use being associated with higher risk of thrombosis. Actuarial freedom from evolution to MF was 97% at 10 years. In conclusion, young ET patients have thrombotic events, especially stroke and venous thrombosis, more frequently than generally considered, whereas they rarely transform to MF.

Polycythaemia vera and essential thrombocythaemia: current treatment strategies

Polycythaemia vera (PV) and essential thrombocythaemia (ET) are classified as Philadelphia-negative chronic myeloproliferative diseases. Both PV and ET are rare diseases, but the prevalence is high. Patients who have not been treated for the diseases are at great risk of morbidity and mortality as a result of thrombohaemorrhagic events. However, if patients have been well treated, their prognosis is good and life-expectancy approaches normal. This article provides diagnostic tools and flowcharts for treatment of PV and ET. Treatment of PV and ET should be risk-adjusted and individualised. Low-dose aspirin is recommended as an antiaggregative drug in both diseases. For PV, phlebotomy to control a haematocrit at <0.45 is the cornerstone in treatment, and treatment with hydroxycarbamide (hydroxyurea) or interferon (IFN)-alpha is added to reduce hypermetabolic symptoms or splenomegaly becoming cytoreductive. In ET, hydroxycarbamide and anagrelide are the most used drugs, and anagrelide may also be added in PV to reduce thrombocytosis. IFNalpha is the only myelosuppressive treatment available during pregnancy. Current controversies regarding treatment illustrate the need for more randomised clinical trials. Demonstration of over expression of the PV-1 gene and in particular the JAK-2 mutation will be novel diagnostic criteria and may have an impact for future therapy of both PV and ET.

Cerebral venous sinus thrombosis associated with essential thrombocytosis in a pediatric patient

Essential thrombocytosis (ET) is an uncommon pediatric hematologic disorder that can result in thrombotic complications, including cerebral venous sinus thrombosis (CVST). Although CVST associated with ET is exceedingly rare, it can be devastating to the patient. We here report a pediatric case of CVST associated with ET. The patient was treated with hydroxyurea and warfarin, which was later replaced by low-dose aspirin. Platelet counts were well controlled after 16 months of follow-up, and no further thrombotic events occurred. Mucositis was the main adverse effect of treatment.

Hydroxyurea therapy: a rare cause of reversible azoospermia

BACKGROUND

Essential thrombocythaemia (ET) is an uncommon chronic myeloproliferative disorder characterized by a marked increase in the number of platelets. Hydroxyurea is effective in preventing thrombosis in high-risk patients with essential thrombocythaemia. In previous studies different side effects of Hydroxyurea have been pointed out, but attention has not really been focused on the possible side effects on spermatogenesis.

CASE

A 35-year-old man under investigation for haematospermia and complaining of erythromyalgia was found to have a thrombocytosis with a platelet count of 1130 x 10(9)/l. Bone marrow aspiration confirmed a diagnosis of essential thrombocythaemia. He was commenced on hydroxyurea (2 g daily) in order to lower his platelet count and relieve the erythromyalgia. The patient represented to the urologists, 3 years later with infertility and a semen analysis done by his doctor had shown azoospermia. Monthly sperm counts after the withdrawal of hydroxyurea showed a gradual return of the spermatogenesis to normal over a period of around 6 months. The patient's wife had conceived within 4 months of him stopping hydroxyurea.

CONCLUSION

This case highlights a very rare but nonetheless important side effect of treatment with hydroxyurea. Hydroxyurea can cause reversible inhibition of spermatogenesis and result in primary infertility. We believe that all patients being commenced on such treatment should be warned of this possibility and that they should be given the necessary follow-up investigations.

Phase I and pharmacokinetic study of Triapine, a potent ribonucleotide reductase inhibitor, in adults with advanced hematologic malignancies

Triapine, a potent inhibitor of ribonucleotide reductase, has demonstrated anti-leukemia activity in pre-clinical models. We conducted a Phase I study of Triapine administered as a 2 h infusion for 5 days in 25 adults with advanced leukemias. We established that Triapine at 96 mg/m2 once a day can be given safely on days 1-5 and 15-19 or 1-5 and 8-12 of a 4-week cycle. When administered twice a day on days 1-5 and 8-12, the maximum tolerated dose of Triapine appears to be 64 mg/m2, although the true criteria for DLT were not met by protocol definition. No CR or PR were observed, but 76% of patients had a >50% reduction in white blood cell counts. At all dose levels, the peak plasma concentration of Triapine (2.2-5.5 microM) was above levels required to achieve in vitro/in vivo leukemia growth inhibition. Based on these data, we conclude that Triapine warrants further investigation in hematologic malignancies.

How I treat patients with polycythemia vera

The clinical course of polycythemia vera (PV) is marked by a high incidence of thrombotic complications; fibrotic and leukemic disease transformations are additional causes of morbidity and mortality. Major predictors of vascular events are increasing age and previous thrombosis; leukocytosis and high JAK2 V617F allele burden are currently being investigated for additional prognostic value in this regard. Myelosuppressive drugs can reduce the rate of thrombosis, but there is concern that their use raises the risk of transformation into acute leukemia. To tackle this dilemma, a risk-oriented management strategy is recommended. Low-risk patients should be treated with phlebotomy and low-dose aspirin. Cytotoxic therapy is indicated in high-risk patients, and the drug of choice is hydroxyurea because of its efficacy in preventing thrombosis and low leukemogenicity. Interferon-alpha should be reserved for selected categories of patients due to high cost and toxicity. The demonstration of JAK2 V617F mutation in the vast majority of PV patients opens the avenue for the development of promising new molecularly targeted drugs.

Essential thrombocythemia

Essential thrombocythemia (ET) is an acquired myeloproliferative disorder (MPD) characterized by a sustained elevation of platelet number with a tendency for thrombosis and hemorrhage. The prevalence in the general population is approximately 30/100,000. The median age at diagnosis is 65 to 70 years, but the disease may occur at any age. The female to male ratio is about 2:1. The clinical picture is dominated by a predisposition to vascular occlusive events (involving the cerebrovascular, coronary and peripheral circulation) and hemorrhages. Some patients with ET are asymptomatic, others may experience vasomotor (headaches, visual disturbances, lightheadedness, atypical chest pain, distal paresthesias, erythromelalgia), thrombotic, or hemorrhagic disturbances. Arterial and venous thromboses, as well as platelet-mediated transient occlusions of the microcirculation and bleeding, represent the main risks for ET patients. Thromboses of large arteries represent a major cause of mortality associated with ET or can induce severe neurological, cardiac or peripheral artery manifestations. Acute leukemia or myelodysplasia represent only rare and frequently later-onset events. The molecular pathogenesis of ET, which leads to the overproduction of mature blood cells, is similar to that found in other clonal MPDs such as chronic myeloid leukemia, polycythemia vera and myelofibrosis with myeloid metaplasia of the spleen. Polycythemia vera, myelofibrosis with myeloid metaplasia of the spleen and ET are generally associated under the common denomination of Philadelphia (Ph)-negative MPDs. Despite the recent identification of the JAK2 V617F mutation in a subset of patients with Ph-negative MPDs, the detailed pathogenetic mechanism is still a matter of discussion. Therapeutic interventions in ET are limited to decisions concerning the introduction of anti-aggregation therapy and/or starting platelet cytoreduction. The therapeutic value of hydroxycarbamide and aspirin in high risk patients has been supported by controlled studies. Avoiding thromboreduction or opting for anagrelide to postpone the long-term side effects of hydrocarbamide in young or low risk patients represent alternative options. Life expectancy is almost normal and similar to that of a healthy population matched by age and sex.

Thrombocytosis and thrombosis

The aim of this review is to discuss current diagnostic approaches to, and classification of, patients presenting with thrombocytosis, in light of novel information derived from the discovery of specific molecular abnormalities in chronic myeloproliferative disorders (CMPD), which represent the most common cause of primary thrombocytosis. The JAK2V617F and the MPLW515L/K mutations have been found in patients with essential thrombocythemia, polycythemia vera, and primary myelofibrosis, and less frequently in other myeloproliferative disorders complicated by thrombocytosis. However, neither mutation is disease specific nor is it universally present in patients with elevated platelet counts due to a CMPD; therefore, distinguishing between reactive and primary forms of thrombocytosis, as well as among the different clinical entities that constitute the CMPD, still requires a multifaceted diagnostic approach that includes as a key step the accurate evaluation of bone marrow histology. The role of elevated platelet counts in thrombosis, which represent the predominant complication of CMPD,significantly affecting prognosis and quality of life as well as, paradoxically, in the pathogenesis of the hemorrhagic manifestations, will be discussed. Established and novel potential risk factors for thrombosis, including the clinical relevance of the JAK2V617F mutation, and current management strategies for thrombocytosis are also briefly discussed.

Navigating the Evolving Paradigms in the Diagnosis and Treatment of Myeloproliferative Disorders

The diagnosis and management of the BCR-ABL–negative myeloproliferative disorders (MPDs) of polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are at an explosive crossroads of scientific investigation and evolving paradigms since the discovery of the tyrosine kinase–activating JAK2V617F mutation in 2005. Additional discovery of relevant molecular lesions (JAK2 exon 12 mutations and c-MplW515L/K) have only further enriched our understanding of MPD pathogenesis. The improved diagnostic certainty these molecular markers provide have resulted in the modification, and simplification, of the World Health Organization (WHO) diagnostic algorithms for MPDs. Despite these scientific advances, however, the initial management of MPDs continues to rely upon a risk-based strategy to minimize the risk of vascular events with control of erythrocytosis, targeted antiplatelet therapy, and risk-based myelosuppressive therapy. No current medical therapy has altered the natural trend of the MPDs to lead to overt severe myelofibrosis or acute leukemia. Investigations into targeted therapies for MPDs are proceeding at a brisk pace with agents aimed at immunomodulation, decreasing marrow stromal reaction to the aberrant clone, DNA hypomethylation, or the inhibition of tyrosine kinases. Specific inhibition of JAK2 itself appears promising by in vitro investigations, and clinical trials with multiple agents are planned to commence enrollment in 2007. The potential impact of JAK2 inhibitors on the manifestations of the MPDs is unclear, but is awaited with great interest.

The burden of fatigue and quality of life in myeloproliferative disorders (MPDs)

BACKGROUND

Few objective data exist on the burden of fatigue and other constitutional symptoms in patients with myeloproliferative disorders (MPD).

METHODS

The authors used validated instruments of fatigue and physical activity assessment during an Internet-based symptom survey of 1179 MPD patients (median age, 56 years; 41.4% men).

RESULTS

The frequency of self-reporting was 80.7% for fatigue, which was substantially higher than that of pruritus (52.2%), night sweats (49.2%), bone pain (43.9%), fever (13.7%), and weight loss (13.1%). In the majority of patients, these symptoms restricted participation in both social functions and physical activity. In addition, 34.5% of patients needed assistance with activities of daily living, and 11.2% reported MPD-associated medical disability. As expected, the presence of myelofibrosis, anemia, splenomegaly, or other features associated with advanced disease favored a higher degree of fatigue. However, fatigue remained the major complaint also in polycythemia vera (84.9%) and essential thrombocythemia (72.4%); these figures were significantly higher than those of published controls (P < .0001).

CONCLUSIONS

The current study identifies fatigue as the major contributor to poor quality of life in MPD, provides baseline information on constitutional symptoms, and underscores the need for the incorporation of quality of life assessment in clinical trials.

Risk stratification for survival and leukemic transformation in essential thrombocythemia: a single institutional study of 605 patients

Unlike the case with thrombosis, prognostic models for survival and leukemic transformation (LT) in essential thrombocythemia (ET) are not available. Among 605 patients with ET seen at our institution and followed for a median of 84 months, 155 died and LT was documented in 20 patients (3.3%). In a multivariable analysis, hemoglobin level below normal (females<120 g/l; males<135 g/l) was identified as an independent risk factor for both inferior survival and LT. Additional risk factors for survival included age > or =60 years, leukocyte count> or =15 x 10(9)/l, smoking, diabetes mellitus and thrombosis. For LT, platelet count> or =1000 x 10(9)/l but not cytoreductive therapy was flagged as an additional independent risk factor. In fact, four of the 20 patients (20%) with LT were untreated previously. We used the above information to construct prognostic models that effectively discriminated among low-, intermediate- and high-risk groups with respective median survivals of 278, 200 and 111 months (P<0.0001), and LT rates of 0.4, 4.8 and 6.5% (P=0.0009) respectively. Presence of JAK2V617F did not impact either survival or LT and mutational frequency was similar among the different risk groups.

Inhibition of tissue factor expression by hydroxyurea in polymorphonuclear leukocytes from patients with myeloproliferative disorders: a new effect for an old drug?

BACKGROUND

Polymorphonuclear leukocytes (PMN) from healthy subjects can produce and store tissue factor (TF), which is expressed on PMN surface upon in vitro stimulation with P-selectin.

RESULTS

We report here that platelets and PMN from 12 patients with myeloproliferative disorders (MPD) (six with polycythemia vera, six with essential thrombocythemia) show up regulation of P-selectin and TF, respectively, in the absence of any in vitro challenge. The number of circulating mixed platelet-PMN aggregates was also increased. PMN TF expression as well as mixed platelet-PMN aggregates, but not platelet P-selectin, were significantly reduced in six MPD patients after treatment with hydroxyurea (HU). In vitro studies performed on PMN separated from healthy donors confirmed HU effects (0-1400 microm). HU prevented both P-selectin-induced TF expression and mixed cell aggregate formation. The inhibitory effect of HU was specific for P-selectin-induced PMN activation, as it did not affect formyl-methionyl-leucyl-phenylalanine-induced PMN TF expression.

CONCLUSIONS

In MPD patients, platelet P-selectin-mediated TF expression on circulating PMN may play a role in thrombus formation and represents a novel target for the antithrombotic activity of HU.

Leukocytosis is a risk factor for thrombosis in essential thrombocythemia: interaction with treatment, standard risk factors, and Jak2 mutation status

Leukocytes contribute to the pathogenesis of thrombosis in essential thrombocythemia (ET) through recently discovered mechanisms of activation and interaction with platelets and endothelial cells. To evaluate whether an increased leukocyte count was associated with thrombosis and whether this effect can be modulated by therapy, we analyzed the clinical course of 439 patients with ET followed at the Ospedali Riuniti di Bergamo. The strength of the association was measured at diagnosis or before thrombotic events by multivariable analyses carried out using data at baseline as well as time-varying covariates. The results showed that (1) an increased leukocyte count at diagnosis was associated with thrombosis during follow-up (“baseline analysis,” relative risk [RR] 2.3, 95% confidence interval [CI] 1.4-3.9, P = .001); (2) hydroxyurea (HU) lowered leukocytosis and reduced the strength of the association between leukocytosis and thrombosis (“time-dependent analysis,” RR 1.6, 95% CI 0.9-2.0, not significant [NS]); (3) the association of leukocytosis and thrombosis was more evident in untreated low-risk patients (RR 2.7, 95% CI 1.2-6.4, P = .01) compared with HU-treated high-risk patients (RR 1.6, 95% CI 0.8-3.2, NS); and (4) the presence of JAK2 V617F was not identified as a risk factor for thrombosis during follow-up despite a significant association between the mutation and leukocytosis. We suggest validation of these findings in prospective clinical studies.

Comparison between anagrelide and hydroxycarbamide in their activities against haematopoietic progenitor cell growth and differentiation: selectivity of anagrelide for the megakaryocytic lineage

Anagrelide (ANA) and hydroxycarbamide (HC) are two distinct pharmacological agents used to treat thrombocythaemia associated with myeloproliferative disorders. Although both drugs have been in clinical use for a number of years, comparative studies of their selectivity and mode of action are still lacking. Here, we have evaluated the activities of ANA and HC on the growth and differentiation of human haematopoietic progenitor cells in liquid culture. Both drugs inhibited thrombopoietin-induced megakaryocytopoiesis in a dose-dependent manner, but with strikingly different potencies (IC(50)=26 nM for ANA and 30 muM for HC) and modes of action. Whereas HC inhibited cell proliferation, ANA acted primarily on the differentiation process. At doses that abrogated megakaryocytopoiesis, HC also inhibited the expansion of CD34(+) cells stimulated by stem cell factor, interleukin-3 and Flt-3 ligand and also induced apoptosis. Furthermore, HC inhibited erythroid and myelomonocytic cell growth, induced by erythropoietin or granulocyte-macrophage colony-stimulating factor, respectively. In contrast, ANA showed none of these additional effects. Taken together, these results demonstrate that ANA is a potent and selective inhibitor of megakaryocytopoiesis, having no significant activity against haematopoietic progenitor cell expansion or differentiation into other lineages. In contrast, the anti-megakaryocytopoietic activity of HC cannot be dissociated from its more general cytoreductive and cytotoxic actions.

Evidence-based management of polycythemia vera

The clinical course of polycythemia vera is marked by significant thrombotic complications and a variable risk of the disease turning either into myeloid metaplasia with myelofibrosis or into acute myeloid leukemia. Cytoreductive treatment of blood hyperviscosity by phlebotomy or chemotherapy and antiplatelet therapy with low-dose aspirin have dramatically reduced the number of thrombotic complications and substantially improved survival. However, there is concern that certain myelosuppressive drugs accelerate the disease progression to acute leukemia. Thus, the objective of management is two-fold: first, to minimize the risk of thrombotic complications; second, to prevent progression to myelofibrotic or leukemic transformation. This chapter provides updated estimates of the risk of thrombosis and disease progression and evaluates the various randomized and observational studies in polycythemia vera, according to an evidence-based approach.

Thrombosis and bleeding in polycythemia vera and essential thrombocythemia: Pathogenetic mechanisms and prevention

Polycythemia vera and essential thrombocythemia are chronic myeloproliferative disorders, the benign clinical course of which can be complicated by both thrombotic and hemorrhagic diatheses. Thrombotic diathesis is characterized by microcirculatory disturbances and by an increased risk of arterial and venous thromboses. Thrombotic accidents often manifest at diagnosis or in the preclinical phase of the disease so that the search for a latent myeloproliferative disorder has become widely recommended in screenings for acquired thrombophilia, particularly when venous thromboses manifest at an unusual site. Hemorrhagic diathesis is more rare, less ominous and mostly affects patients with a very high platelet count. In these subjects, an altered degradation and function of von Willebrand factor can cause minor mucocutaneous hemorrhages, which are sometimes a prelude to major gastrointestinal bleedings. The bleeding tendency can be effectively treated by cytoreduction. Pathogenesis and treatment of thrombotic diathesis are still controversial. The nature of disease-related hemostatic abnormalities and the role of common risk factors are far from being elucidated. In polycythemic subjects, treatment of blood hyperviscosity is essential and low-dose aspirin, which has an established antithrombotic efficacy, should always be used in the absence of contraindications. These are mostly constituted by conditions of increased bleeding risk, which, in particular, have to be evaluated when considering aspirin use in patients with essential thrombocythemia. Future clinical research should primarily aim to assess the risk/benefit ratio of aspirin use in this disease, to better characterize the determinants of vascular risk and to reduce the high incidence of leukemias in patients with these diseases. This might require either the availability of safer cytoreductive agents or, alternatively, the use of more aggressive antiplatelet regimens in patients at high thrombotic risk.

Essential thrombocythaemia

Essential thrombocythaemia is a myeloproliferative disorder that results from the transformation of a multipotent haematopoietic progenitor. Its diagnosis can be challenging and its optimal management has been controversial, largely because of a virtual absence of randomised trials. However, this situation will be dramatically altered by two recent developments. First, the Medical Research Council Primary Thrombocythaemia 1 (PT-1) trial-the largest and most comprehensive randomised study of any myeloproliferative disorder-provides clear guidance on the management of patients with high-risk essential thrombocythaemia. Second, identification of a unique JAK2 mutation in a substantial proportion of patients with essential thrombocythaemia (and also other myeloproliferative disorders) has resulted in a powerful diagnostic tool and is likely to alter approaches to both the classification and management of the myeloproliferative disorders.

Current management of the myeloproliferative disorders: a case-based review

CONTEXT

Properly managed, the myeloproliferative disorders are generally compatible with prolonged survival. Challenges to the hematologist include knowing when and how best to intervene to prevent and manage complications. The cytoreductive agent of choice for these disorders is currently hydroxyurea, emerging from randomized trials beginning with those of the Polycythemia Vera Study Group.

OBJECTIVE

To examine the roles and shortcomings of interventions (including hydroxyurea, antiplatelet agents, anagrelide, interferon, thalidomide, alkylating agents, cell cytopheresis, erythropoietins, splenectomy, bone marrow transplantation, and imatinib) for myeloproliferative disorders.

DATA SOURCES

This report uses actual case histories to illustrate the roles and shortcomings of these interventions.

CONCLUSIONS

Beyond phlebotomy for polycythemia vera, patients with polycythemia vera and essential thrombocythemia can be stratified by their risk for thrombosis, which guides the institution of cytoreductive therapies. High-risk patients generally benefit from cytoreductive therapy, and hydroxyurea has emerged as the agent of choice, because alkylating agents (and P32) have high leukemogenic potentials. Anagrelide and interferon are second-line agents. The addition of low-dose aspirin is beneficial for most, helping to prevent arterial thrombotic complications. Therapy in any of these disorders should be tailored to the unique characteristics of the individual patient. With myelofibrosis, therapeutic options run the gamut from observation, erythropoietic stimulators, cytotoxic agents, splenectomy, and bone marrow transplantation. Thalidomide and imatinib have shown some utility. Future challenges are the refinement of individualized treatment strategies and the development of targeted therapies based on rapidly expanding understanding of the molecular perturbations in these disorders.

Practical management of classical myeloproliferative disorder patients: a clinician's guide

The classical myeloproliferative disorders (MPDs) are comprised of the clonal, BCR-ABL-negative, chronic myeloid disorders of essential thrombocythemia, polycythemia vera, and myelofibrosis with myeloid metaplasia. Management of these disorders remains a significant challenge due to the varied range of prognosis and phenotypic manifestations. Curative therapy, achieved in some patients through allogeneic stem cell transplantation, is elusive or inappropriate in most. Additionally, no available medical therapy has been shown to clearly improve survival or delay disease progression. Current management involves an emphasis on prevention of thrombohemorrhagic complications (through aspirin treatment, phlebotomy and cytoreduction in high-risk patients) in early-stage patients and symptomatic care in those with advanced disease. Leukemic transformation from MPDs remains a rapidly fatal complication, unresponsive to current therapies. Recent elucidation of the role of the activating tyrosine kinase mutation JAK2 (V617F) is anticipated to usher in an era of greater understanding and targeted therapy for the MPDs.

Best practice in primary care pathology: review 3

This best practice review examines four series of common primary care questions in laboratory medicine: (i) "minor" blood platelet count and haemoglobin abnormalities; (ii) diagnosis and monitoring of anaemia caused by iron deficiency; (iii) secondary hyperlipidaemia and hypertriglyceridaemia; and (iv) glycated haemoglobin and microalbumin use in diabetes. The review is presented in question-answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. They are not standards, but form a guide to be set in the clinical context. Most of the recommendations are based on consensus rather than evidence. They will be updated periodically to take account of new information.

Abdominal vein thrombosis in essential thrombocythemia: prevalence, clinical correlates, and prognostic implications

Among 460 consecutive patients with essential thrombocythemia (ET) seen at our institution, 19 cases (4%) of abdominal vein thrombosis (AVT) were documented either at (n = 9) or after (n = 10) diagnosis. Women (P = 0.03) and the young (P = 0.002) were preferentially affected. Accordingly, clinical comparisons were performed among three groups of female patients: those with AVT (group A; n = 17), a control group without AVT but closely matched to group A in terms of age and year of diagnosis (group B; n = 34), and all female patients without AVT (group C; n = 288). As expected from the consequences of AVT-associated portal hypertension and anticoagulant therapy, patients in group A experienced significantly higher rates of hemorrhage, palpable splenomegaly, and anemia. Unexpectedly, however, compared with group B, group A displayed both a higher conversion rate into myelofibrosis/acute leukemia (P = 0.0008) and a shorter median survival (116 vs. 156 months; P = 0.0012). Multivariable analysis including all female patients with ET identified AVT, along with advanced age, leukocytosis, and tobacco use, as an independent risk factor for inferior survival. Groups A, B, and C did not differ in either JAK2(V617F) mutational frequency or incidence of non-abdominal thrombosis. We conclude that AVT in ET is a marker of aggressive disease biology.

A phase II trial of pegylated interferon alpha-2b therapy for polycythemia vera and essential thrombocythemia: feasibility, clinical and biologic effects, and impact on quality of life

BACKGROUND

Conventional interferon-alpha (IFN) is an effective treatment for patients with myeloproliferative disorders. However, many patients discontinue therapy because of side effects.

METHODS

In this 24-month, Phase II feasibility study of pegylated interferon alpha-2b (PEG-IFN) treatment, a starting dose of 0.5 microg/kg per week was received by 21 patients with polycythemia vera (PV) and 21 patients with essential thrombocythemia (ET). The treatment objective, a complete platelet response (CR), was a platelet count<400x10(9)/L in symptomatic patients and <600 in asymptomatic patients. Neutrophil polycythemia rubra vera-1 (PRV-1) messenger RNA expression was analyzed prior to and during therapy. Quality of life (QoL) was investigated by using the European Organization for Research and Treatment of Cancer QLQ-C30 questionnaire.

RESULTS

At 6 months, 29 of 42 patients (69%) had achieved a CR after a median of 83 days. The CR rate was not related to diagnosis, gender, or previous therapy. Nineteen patients completed the planned 2-year treatment in CR. No thromboembolic or bleeding complications were observed. Phlebotomy requirements were reduced in the majority of patients with PV. Five of 14 patients (36%) who initially were positive for PRV-1 achieved normalized PRV-1 expression under PEG-IFN treatment. Side effects were the cause of therapy failure in 16 of 23 patients. However, only 8 of 19 patients reported any side effects at 2 years. The QLQ-C30 revealed clinically significant impairments in several aspects of QoL at 6 months; however, at 2 years, QoL measurements were not different from baseline.

CONCLUSIONS

PEG-IFN effectively reduced platelet counts in 29 of 42 patients, but only 19 patients maintained a CR at 2 years. The reversal of PRV-1 positivity noted in a subset of patients suggested that PEG-IFN may have an effect on the malignant clone. PEG-IFN is a valuable therapeutic alternative for patients who tolerate its initial side effects.

Leg ulcers in elderly on hydroxyurea: a single center experience in Ph- myeloproliferative disorders and review of literature

Hydroxyurea (HU) is effective in controlling thrombocytosis while reducing the risk of thrombosis in essential thrombocythemia (ET), polycythemia vera (PV) and myelofibrosis (MF). However, HU may carry more or less severe side-effects. Rare cases of patients with painful leg ulcers have been published. We report our experience on such a side-effect in a large cohort of patients with ET and PV treated with HU and review the literature on the topic. Five (4%) out of our 124 patients (69 ET, 51 PV, 4 MF; 49 males, 75 females; mean age at diagnosis 59.1+/-11.8 years) treated with HU developed painful leg ulcers. Sixty-one other patients affected with Phmyeloproliferative disorders (Ph- MPD) developing HU-related painful leg ulcers are described in the English literature. All our five patients were women and developed leg ulcers over the age of 75. Sixty-five percent of all described cases are women; 59% were over 65 years of age and 45% over 70. Most cases received over 1 gr HU per day for at least 1 year. The pathogenesis of HU-induced skin ulcers remains elusive. Treatment is difficult and requires prompt cessation of HU therapy.

Molecular basis of the diagnosis and treatment of polycythemia vera and essential thrombocythemia

Recent insights into the molecular mechanisms of polycythemia vera (PV) and essential thrombocythemia (ET) are challenging the traditional diagnostic classification of these myeloproliferative disorders (MPDs). Clonality analysis using X-chromosome inactivation patterns has revealed apparent heterogeneity among the MPDs. The recently discovered single somatic activating point mutation in the JAK2 gene (JAK2-V617F) is found in the great majority of patients with PV, but also in many patients with phenotypically classified ET and other MPDs. In contrast to the acquired MPDs, mutations of the erythropoietin receptor and thrombopoietin receptor have been identified in familial forms of nonclonal erythrocytosis and thrombocytosis, respectively. The mechanisms of major clinical complications of PV and ET remain poorly understood. Quantitative or qualitative abnormalities of red cells and platelets do not provide clear explanations for the thrombotic and bleeding tendency in these MPDs, suggesting the need for entirely new lines of research in this area. Recently reported randomized clinical trials have demonstrated the efficacy and safety of low-dose aspirin in PV, and an excess rate of arterial thrombosis, major bleeding, and myelofibrotic transformation, but decreased venous thrombosis, in patients with ET treated with anagrelide plus aspirin compared to hydroxyurea plus aspirin.