Acute myeloid leukemia (AML) having evolved from essential thrombocythemia (ET): distinctive chromosome abnormalities in patients treated with pipobroman or hydroxyurea

Occurrence of acute myeloid leukemia in hydroxyurea-treated sickle cell disease patient

Hydroxyurea (HU) has been widely used in sickle cell disease. Its potential long-term risk for carcinogenesis or leukemogenic risk remains undefined. Here, we report a 26 y old African-American female with Sickle Cell Disease (SCD) who developed refractory/relapsed acute myeloid leukemia (AML) 6 months after 26 months of HU use. That patient's cytogenetics and molecular genetics analyses demonstrated a complex mutation profile with 5q deletion, trisomy 8, and P53 deletion (deletion of 17p13.1). P53 gene sequence studies revealed a multitude of somatic mutations that most suggest a treatment-related etiology. The above-mentioned data indicates that the patient may have developed acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) as a direct result of HU exposure.

Essential thrombocytosis with recurrent spontaneous abortion in the mid trimester: A case report

RATIONALE

Essential thrombocytosis (ET) is a myeloproliferative neoplasm characterized by clonal proliferation of the megakaryocytic lineage within the bone marrow and phenotypically by an elevated platelet count in peripheral blood. Common vascular complications include thrombosis, microvascular disturbances, and hemorrhage. ET with recurrent spontaneous abortion as the primary symptom is rare.

PATIENT CONCERNS

A 30-year-old pregnant woman (gestational age: 8 weeks) with a history of recurrent spontaneous abortion in the mid trimester was admitted to our hospital for further management.

DIAGNOSIS

The diagnosis of ET was made based on the platelet count, bone marrow biopsy, and molecular biology testing.

INTERVENTIONS

The patient was treated with interferon, heparin, and aspirin.

OUTCOMES

The infant was delivered by cesarean section without complication at 28 weeks gestation due to placental abruption. The child remained healthy with no developmental abnormalities during follow-up for 2 years.

LESSONS

Recurrent spontaneous abortion in the mid trimester might be associated with ET. Thus, a detailed investigation including blood routine examination to identify an abnormal platelet count is warranted for pregnant patients with such a history in order to facilitate timely treatment.

Leukemic transformation in essential thrombocythemia

Essential thrombocythemia patients develop acute myeloid leukemia (AML) at a rate of 1-4% during a median follow-up of 7-10 years. The risk increases with advanced age, anemia, platelet count ≥ 1000 × 10(9)/l, the presence of ≥ 2 somatic mutations and after the first decade of diagnosis. The use of alkylating agents and (32)radiophosphorus, particularly in higher doses, but not hydroxyurea and anagrelide, increases the risk. AML in essential thrombocythemia patients is frequently associated with unfavorable cytogenetics and poor prognosis. In young and fit patients, AML-type induction chemotherapy followed by allogeneic stem cell transplantation may offer the best chance of long-term disease control. In select elderly patients with poor performance status, hypomethylating agent such as azacytidine may prolong survival.

inv (4)(p13q13) in patient with essential thrombocythemia: A case report

The inv (4)(p13q13) cytogenetic abnormality is uncommon in hematologic malignancies. So far, it has not been previously reported in patients with essential thrombocythemia (ET). We report a first case of ET with inv (4)(p13q13) karyotype in a 69-year-old female patient who developed myelofibrosis at follow up. Conventional cytogenetic analysis from a bone marrow sample showed 46, XX, inv (4)(p13q13) [3]/46, XX [4] at diagnosis and subsequent analysis revealed the same abnormal karyotype during the myelofibrosis phase (46, XX, inv (4)(p13q13) [13]/46, XX [26]). The prognostic significance of this chromosomal abnormality is unknown.

Hydroxycarbamide: a user's guide for chronic myeloproliferative disorders

Hydroxycarbamide is a nonalkylating antiproliferative and antiviral agent that has been used for over 40 years to treat a variety of neoplastic and non-neoplastic conditions. Hydroxycarbamide is readily absorbed and widely distributed throughout the body. It acts primarily to inhibit DNA synthesis, which underpins its use in solid tumors, viral infections and chronic myeloproliferative disorders. Hydroxycarbamide is an effective treatment for preventing transient ischemic attacks associated with thrombocytosis in chronic myeloproliferative disorders because it is a nitric oxide donor. While its mechanism of action and side-effect profile are well defined, its potential for leukemic transformation as a single agent is still a matter of controversy. Based on a search of the Medline database, this article encompasses the pharmacokinetics, pharmacodynamics, clinical use and tolerability of hydroxycarbamide, plus its potential for mutagenicity with special reference to the chronic myeloproliferative disorders. The toxicity profile of hydroxycarbamide is also discussed to enable clinicians to balance potential risks with therapeutic benefits.

Should Chemotherapy Be Administered for Essential Thrombocythemia (ET) Patients with Leukemic Transformation?

Introduction:

Essential Thrombocythemia (ET) is a clonal myeloproliferative disease presenting predominantly with thrombocytosis. One of its rare complications is leukemic transformation (LT). Once leukemic transformation occurs, prognosis is dismal. We aim to determine the disease profile of LT in our ET patients and evaluate if chemotherapy can alter prognosis.

Methods:

Clinical data of all patients diagnosed and treated with ET from 1999 to 2008 in the Department of Hematology, Singapore General Hospital, were captured in the Myeloproliferative Disease(MPD) Registry. ET patients with LT were selected. Patient characteristics, disease profile, including ET treatment, duration from ET diagnosis to LT, prior myelofibrosis (MF) history, type of chemotherapy, response and eventual survival were recorded.

Results:

Two hundred and thirty ET patients were diagnosed and treated from 1999 to 2008. Six patients had LT (2.6%). All were Chinese. Four were females. Age range was 47–70 years (mean 61.2 years). Transformation to acute myeloid leukemia (AML) was seen in 5 patients, after a latency period of 3–28 years. Acute biphenotypic leukemia was diagnosed in 1 patient 4 years after ET diagnosis. All patients had received hydroxyurea. There was no prior evolution to MF. Complex cytogenetics were seen in all cases. Three patients treated conservatively died within 1 month. The other 3 patients did not go into durable complete remission despite chemotherapy and succumbed within 9 months.

Conclusions:

Leukemic transformation in ET, though rare, is associated with grave prognosis. Outcome with chemotherapy is dismal. More studies are needed to evaluate if alternative treatment can improve survival.

Long-term follow-up of 386 consecutive patients with essential thrombocythemia: safety of cytoreductive therapy

Cytotoxic agents like Hydroxyurea, Busulfan and Interferon-alpha are to date the most commonly used therapeutic approaches in Essential Thrombocythemia (ET). However, few data on the efficacy and safety of these agents in the long-term are currently available. We report a retrospective analysis of the long-term outcome of 386 consecutive ET patients, followed at single Institution for a median follow-up of 9.5 years (range, 3-28.5). Cytoreductive therapy was administered to 338 patients (88%), obtaining a response in 86% of cases. Forty-five patients (12%) experienced a thrombosis. Among baseline characteristics, only history of vascular events prior to ET diagnosis predicted a higher incidence of thrombosis. Evolution in acute leukemia/myelofibrosis occurred in 6 (1,5%) and 20 (5%) patients, and was significantly higher in patients receiving sequential cytotoxic agents. Overall survival was 38% at 19 years and was poorer for patients older than 60 years, with higher leukocytes count (>15 x 10(9)/L), hypertension and mellitus diabetes at ET diagnosis and for patients experiencing a thrombotic event during follow-up. Cytoreductive therapy was effective in decreasing platelet number with negligible toxicity; however, thrombocytosis control did not reduce the incidence of thrombosis and, for patients who received sequential therapies, the probability of disease evolution was higher and survival was poorer.

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.

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.

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.

Essential thrombocythemia: a review of diagnostic and pathologic features

CONTEXT

Essential thrombocythemia (ET) is a chronic myeloproliferative disorder (CMPD) characterized predominately by thrombocytosis and abnormal megakaryocyte proliferation. The current diagnostic criteria require a combination of clinical, histologic, and cytogenetic data. The diagnosis relies largely on exclusion of other causes of thrombocytosis.

OBJECTIVE

Describe historical, clinical, and laboratory features of ET in order to understand, clarify, and more accurately diagnose this entity.

DATA SOURCES

Review contemporary and historical literature on ET and other causes of thrombocytosis.

CONCLUSIONS

ET is a relatively indolent and often asymptomatic CMPD that is characterized primarily by a sustained elevation in platelets > or = 600 x 10(3)/microL (> or = 600 x 10(9)/L), proliferating enlarged and hyperlobated megakaryocytes, and minimal to absent bone marrow fibrosis. Significant changes and revisions to the diagnostic requirements and criteria for ET have occurred during the last 30 years. Recently, a mutation in the Janus kinase 2 (JAK2) gene has been found in a significant number of cases of ET and other CMPDs. In up to 57% of ET cases, a mutation in the JAK2 gene can be detected. In the absence of a JAK2 mutation and features of another CMPD, the diagnosis of ET remains a diagnosis of exclusion after other causes of thrombocytosis have been excluded.

t(3;21)(q26;q22) in myeloid leukemia: an aggressive syndrome of blast transformation associated with hydroxyurea or antimetabolite therapy

BACKGROUND

The t(3;21)(q26;q22) translocation is associated with myeloid leukemias and results in a chimeric oncoprotein containing AML1/RUNX1 variably fused to EAP, MDS1, and/or EVI1.

METHODS

The current study describes what to the authors' knowledge is the first large case series reported to date of 26 t(3;21)(q26;q22)-associated leukemias, in which 24 cases arose after chemotherapy. Conventional G-band karyotyping and flow cytometry immunophenotyping were performed. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect fusion transcripts between AML1 and EAP, MDS1, or EVI1, followed by DNA sequencing.

RESULTS

In all 16 patients with chronic myeloproliferative disorders, including 14 with chronic myelogenous leukemia (CML), the occurrence of t(3;21) heralded myeloid blast transformation. Fifteen (93%) patients had been previously treated with hydroxyurea. Eight patients with chronic myeloproliferative disorders (CMPD) were found to have t(3;21) with t(9;22) as the sole cytogenetic abnormality; in 5 other patients this was accompanied by trisomy 8. Among 10 cases of t(3;21)-associated acute myeloid leukemia, 8 were secondary tumors after chemotherapy for other neoplasms that had been treated with regimens including fludarabine and 5-fluorouracil in 3 patients each and etoposide in 2 patients. The immunophenotype of the blasts in all 22 tested cases was similar, with uniform expression of myeloid markers and CD34 and variable expression of CD7 and CD9, but minimal morphological myeloid maturation. Dysplastic micromegakaryocytes and bone marrow fibrosis were observed predominantly in CMPD cases. RT-PCR followed by DNA sequencing showed that the AML1-/MDS1-/EVI1 (AME) fusion transcript was detected in all 5 cases assessed. Among the patients with CMPD, 8 died of disease (at a median of 6.5 mos) and 5 achieved disease remission with bone marrow transplantation. Among patients with acute myeloid leukemia/myelodysplastic syndrome, 7 died of disease (at a median of 2 mos) and 2 had persistent leukemia with short follow-up.

CONCLUSIONS

Activation of AME through t(3;21) defines a highly aggressive, therapy-related leukemic blast syndrome. Prior treatment with hydroxyurea or other antimetabolites is implicated as a contributory cause.

De novo appearance of der(1;7)(q10;p10) is associated with leukemic transformation and unfavorable prognosis in essential thrombocythemia

Leukemic transformation or myelofibrosis is a major concern in managing patients with chronic myeloproliferative disorders, including essential thrombocythemia (ET). We analyze the relationship between cytogenetic changes and the transformation in 89 patients with ET; 8 patients experienced transformation, including 2 patients with acute leukemia following myelofibrosis, 3 with acute leukemia, and 3 with myelofibrosis. Among the eight patients showing transformation, two patients developing myelofibrosis derived from a group with normal cytogenetics, but the remaining six were categorized as showing de novo appearance of cytogenetic changes. Two leukemia patients had de novo cytogenetic changes at the time of leukemia diagnosis, whereas two patients with acute leukemia following myelofibrosis showed der(1;7) during their myelofibrosis period. Moreover, patients with der(1;7) did not receive any cytotoxic agents before the appearance of der(1;7), indicating that detection of der(1;7) may have predictive value for not only leukemic transformation but also unfavorable prognosis.

Risk-adapted therapy in essential thrombocythemia and polycythemia vera

The clinical course of Polycythemia vera (PV) and Essential Thrombocythemia (ET) is marked by an high incidence of thrombotic complications, which represent the main cause of morbidity and mortality. Major predictors of vascular events are increasing age and previous thrombosis. Myelosuppressive drugs can reduce the rate of thrombosis, but there is concern that their use raises the risk of PV and ET transformation into acute leukemia. To tackle this dilemma, a risk-oriented management strategy is recommended. Low-risk patients with PV should be treated with phlebotomy and low-dose aspirin, whereas those with ET can be left untreated. Cytotoxic therapy is indicate in high-risk patients and the drug of choice is hydroxyurea because its leukemogenicity is low, if any. New therapeutic options, theoretically devoid of leukemic risk, such as alpha-interferon, anagrelide and imatinib should be reserved to selected patients and require further clinical experience.

[Treatment of essential thrombocythemia]

PURPOSE

Essential thrombocythemia (ET) is a myeloproliferative syndrome that rises many therapeutic problems. This affection is rarely life threatening, but hemorrhagic and thrombotic complications must be prevented when possible. The rarity of these complications makes difficult the assessment of treatment efficiency. Few randomised clinical trials were done, and treatment often rests on retrospective studies. The potential toxicity of treatments, their leukemogenicity in particular, rises a decisional problem for young patients. We propose to review available data in order to propose the most rational treatment for each patient.

CURRENT KNOWLEDGE AND KEY POINTS

After numerous years when we only disposed of retrospective studies, non-randomised prospective studies or isolated case-reports, two randomised trials allows us to more precisely define ET treatment. The first trial proved the efficiency of the hydroxyurea-aspirin association in the prevention of thrombotic events in high-risk patients. The second trial signalled to our attention the increased risk of bleeding of the association anagrelide-aspirin, with also the possibility of increased appearance of myelofibrosis.

FUTURE PROSPECTS AND PROJECTS

New perspectives in the treatment of ET will require to get more insights in the role of hydroxyurea and anagrelide in particular by longer follow-up. But not less important is a better definition of the thrombosis risks (who has to be treated?) and also of the diagnostic groups since ET can, in some particular cases, be misdiagnosed with polycythemia vera or idiopathic myelofibrosis.

Essential thrombocythaemia: challenges and evidence-based management

Essential thrombocythaemia was first described over 70 years ago. This condition is dominated by thrombotic and haemorrhagic complications and, in the long-term, by risk of transformation to myelofibrosis and/or acute leukaemia. However, it is heterogeneous both clinically and biologically. Here, a review of current concepts in disease aetiology and management is offered with reference to recent focused reviews where appropriate. In addition, five specific areas are discussed in detail: the role of the trephine biopsy, the disease entity prefibrotic myelofibrosis; the recently described Janus kinase 2 (JAK2) mutations; the leukaemogenicity of hydroxyurea (hydroxycarbamide); and lastly, the implications of the results of the Medical Research Council Primary Thrombocythaemia 1 study are explored.

Flow cytometry evaluation of erythroid and myeloid dysplasia in patients with myelodysplastic syndrome

The purpose of this study was to develop a flow cytometric approach to the evaluation of marrow dysplasia in myelodysplastic syndromes (MDS). We first studied a cohort of 103 MDS patients as well as 46 pathological and healthy controls. Flow cytometry data were expressed as percentage of positive cells. Analysis of erythroid cells showed higher proportions of immature cells (P < 0.001) and decreased levels of CD71 expression on nucleated red cells (P = 0.02) in MDS. Analysis of myeloid cells showed lower proportions of CD10+ and higher proportions of CD56+ granulocytes (P < 0.001), and increased ratios of immature to mature cells (P = 0.007). Since no single immunophenotype could accurately differentiate MDS from other conditions, we used discriminant analysis for generating erythroid and myeloid classification functions using combinations of immunophenotypic parameters. These functions were prospectively validated in a testing cohort of 69 MDS patients and 46 pathological controls. A diagnosis of MDS was obtained in 60/69 cases (87%). No false-positive results were noticed among controls. Significant correlations between values of these functions and both degree of morphological dysplasia and the International Prognostic Scoring System were found. These findings indicate that flow cytometry evaluation of marrow dysplasia is feasible and may be useful in the work-up of individual MDS patients.

Essential thrombocythemia terminating in pure erythroleukemia

Transformation into acute leukemia is a rare event in essential thrombocythemia (ET). The blasts are usually of myeloid, rarely of megakaryoblastic differentiation. We present the case of a patient with pure erythroleukemia after a nearly 10-year course of ET, which was treated with hydroxyurea. The patient, a 58-year-old male, presented with an elevated thrombocyte count (926,000/microL) and normal values of hemoglobin and leukocytes. After 10 years of therapy with hydroxyurea, the patient developed acute leukemia of solely erythroid differentiation. Chemotherapy with cytarabine and daunorubicin resulted in incomplete remission. The patient died 2 months after diagnosis of acute erythroleukemia. Transformation of ET into erythroleukemia may demonstrate the pluripotent potential of the neoplastic hemopoietic stem cell, with the ability to cause acute leukemia not only of myeloid or megakaryoblastic but also of erythroid lineage.

Spontaneous evolution of essential thrombocythaemia into acute megakaryoblastic leukaemia with trisomy 8, trisomy 21 and cutaneous involvement

Spontaneous transformation of essential thrombocythaemia (ET) into acute leukaemia is rare. We describe a case of ET that spontaneously transformed after 19 yrs uneventful follow-up into acute megakaryoblastic leukaemia. Cytogenetic analysis of bone marrow nucleated cells showed trisomy 8 and trisomy 21 at time of leukaemic transformation supporting the hypothesis that chromosomal abnormalities are part of the mechanism that drives the leukaemic progression independently of drug cytotoxicity. In addition, the very rare and intriguing finding of M7 FAB subtype evolution of ET was complicated by cutaneous involvement in the leukaemic process.