Philadelphia-positive acute leukemia. Cytogenetic and molecular aspects

Acute Myeloid Leukemia with BCR/ABL Fusion Chimera

Philadelphia (Ph) chromosome is most commonly associated with chronic myelogenous leukemia (CML), a subset of precursor B-cell acute lymphoblastic leukemia and acute biphenotypic leukemia. In contrast only 1 % of acute myeloid leukemia (AML) show a consistent association with the Ph Chromosome. Before making a diagnosis of Ph + AML stringent criteria need to be applied in order to differentiate it from blast crisis stage of CML. It is important to identify this rare entity as patients who otherwise carry a poor prognosis with standard chemotherapy regimen, would benefit from therapy with imatinib mesylate. This article discusses the morphological, immunophenotype and clinical characteristics of a rare case of Ph + AML.

Mechanisms and impacts of chromosomal translocations in cancers

Chromosomal aberrations have been associated with cancer development since their discovery more than a hundred years ago. Chromosomal translocations, a type of particular structural changes involving heterologous chromosomes, have made a critical impact on diagnosis, prognosis and treatment of cancers. For example, the discovery of translocation between chromosomes 9 and 22 and the subsequent success of targeting the fusion product BCR-ABL transformed the therapy for chronic myelogenous leukemia. In the past few decades, tremendous progress has been achieved towards elucidating the mechanism causing chromosomal translocations. This review focuses on the basic mechanisms underlying the generation of chromosomal translocations. In particular, the contribution of frequency of DNA double strand breaks and spatial proximity of translocating loci is discussed.

Late-appearing Philadelphia chromosome in childhood acute myeloid leukemia

A 3-year-old female was diagnosed with acute myeloid leukemia (AML-M2). The disease was refractory to various chemotherapeutic agents. Cytogenetic analysis revealed a clone with trisomy 8 at diagnosis that was replaced by a clone containing a t(11;15) and del(20q) by the end of the second induction. A new clone, characterized by a Philadelphia chromosome, with the minor BCR/ABL p190 transcript, emerged 14 months after diagnosis and remained to the end of disease course. The late occurrence of the Philadelphia chromosome in AML has been documented rarely in adults.

Secondary Philadelphia chromosome in a patient with acute lymphoblastic leukemia

We report the case of a patient with acute lymphoblastic leukemia who developed a secondary Philadelphia chromosome-positive clone (Ph(+)). Although the Ph was not detected at diagnosis with conventional cytogenetic analysis and with molecular methods (reverse transcriptase polymerase chain reaction), the Ph was detected with the same techniques at relapse. This anomaly is usually related to the initiation of the disease, but can be a late event related to progression. We discuss these hypotheses and review the literature.

Megakaryocytic blast crisis as a first presentation of chronic myeloid leukemia

Acute megakaryocytic leukemia (AmegL) corresponds to 5.0-10.0% of all acute myeloid leukemias (AML). Blast crisis as the first presentation of chronic myeloid leukemia (CML) accounts for 10.0% of all cases.

OBJECTIVE

We report a case of megakaryocytic blast crisis as the first presentation of CML.

CASE REPORT

A 25-yr-old-female with a 2-month history of dry cough and a large, non-tender splenomegaly was found to have a hemoglobin concentration of 10.5 g/dL, a hematocritof 33.0%, a white blood cell count (WBC) of 11.4 x 106 L with 38% small blasts, eosinophilia of 5%, basophilia of 8%, and a platelet count of 580 x 109 L. Bone marrow aspiration revealed 24% of blast cells with cytoplasmatic blebs and hyperplastic megakaryocytic lineage with dysplasia. Cytochemical stains were all negative, immunophenotyping studies showed CD41 and CD61 positivity in blast cells. Bone marrow biopsy showed grade II fibrosis. Karyotype revealed 46, XX, t(9,22) (q34.1;q11.2)[20] and the reverse-transcriptase-PCR (RT-PCR) gave rise a product with a size corresponding to the 210 kDa protein (p210). No matched donor was found. After induction therapy 5.9% of blast cells persisted. The patient received Imatinib Mesylate and is doing well after a 12-month follow-up.

DISCUSSION

AmegL as the first presentation of CML is a rare and often fatal event. Some characteristics point towards the diagnosis of a blast crisis instead of AmegL de novo with t(9,22).

Chromosome translocations: dangerous liaisons revisited

Although it has been clear for more than a century that the chromosomes in human tumour cells are often wildly abnormal, there has been controversy as to whether these changes are primary events or are merely secondary epiphenomena that reflect the genomic instability of these cells. The prevailing view for most of this period was that chromosome changes were secondary events. What happened to change this view?

The existence of lymphoid lineage restricted Philadelphia chromosome-positive acute lymphoblastic leukemia with heterogeneous bcr-abl rearrangement

Analysis of lineage involvement was performed in 17 Philadelphia chromosome-positive acute lymphoblastic leukemia patients with no history of chronic myeloproliferative disorder. The percentage of blastic cells as defined by flow cytometry matched that of the Ph-positive cells in 14 out of 17 patients. The bcr-abl rearrangement was investigated by fluorescent in situ hybridization in morphologically identified blastic cells, myeloid elements, lymphocytes and erythroblasts using a combined light and fluorescent microscopical imaging. Lymphoid lineage restriction could be determined in all but three of the patients. These 14 patients exhibited heterogeneity in terms of m-bcr and M-bcr types of translocation as revealed by reverse transcription polymerase chain reaction. The three patients with multilineage involvement and M-bcr type of translocation reverted to chronic phase and the percentage of Ph-positive cells remained high. Thus, we could identify an uncommitted stem cell origin among Ph-positive ALLs only in those patients whose disease subsequently proved to be a lymphoid blastic crisis with clinically silent chronic phase.

The Philadelphia chromosome as a secondary change in leukemia: three case reports and an overview of the literature

Three cases of acute nonlymphocytic leukemia with a Philadelphia chromosome (Ph) as a secondary abnormality are reported. The Ph was late-appearing in one patient and appeared as an additional anomaly in the other two patients. Fluorescence in situ hybridization studies of the first patient identified the presence of a minor BCR/ABL rearrangement. The findings of these cases support the conclusion that the Ph plays a role not only in leukemogenesis, but also in disease progression. An overview of the literature dealing with similar cases is also presented.

Therapeutic management of hematological malignancies in elderly patients. Biological and clinical considerations. Part 1. Myelodysplasias and the acute leukemias

The different therapeutic options that may be employed in the treatment of elderly patients with acute leukemias and myelodysplastic states are considered following an analysis of certain biological features, that have been investigated by cytochemical, cytogenetic and cytokinetic techniques, immunophenotyping, and studies on G-6-PD isoenzymes. These studies imply that in the elderly the pattern of hematological malignancies and the lack of response to conventional treatment derive from intrinsic biological differences between these pathological states in older and younger patients. Treatment in elderly patients has ranged from palliative treatment to intensive chemotherapy, often with disappointing results in both cases. Palliative treatment does not induce remissions, and median survival is short. On the other hand, elderly patients do not tolerate well both induction and post-remission therapy due to the degree of toxicity and the effects of drug-induced pancytopenia. In this scenario, in vitro drug-sensitivity testing and karyotyping assume increasing importance, because they may predict which patients are likely to benefit from intensive therapy. In both acute leukemias and myelodysplasias, treatment ideally should be designed case by case, according to the hematological, clinical and biological features.

Cytogenetic and molecular genetic methods for diagnosis and treatment response in chronic granulocytic leukemia

Today, laboratory geneticists help clinical hematologists diagnose chronic granulocytic leukemia (CGL) and monitor the response of patients undergoing treatment. The most common genetic tests for CGL include quantitative cytogenetic studies, fluorescence in situ hybridization with probes for BCR and ABL, Southern blot analysis, and reverse transcriptase polymerase chain reaction. No single genetic testing procedure fulfills all the needs of clinicians who care for patients who have CGL. Thus, it has become important to use combinations of testing methods that are both accurate and cost-effective for any given clinical situation in the diagnosis and treatment of patients with CGL.

ider(9)(q10)t(9;22)(q34;q11) is a recurrent chromosomal abnormality in acute lymphoblastic leukemia and lymphatic blastic phase of chronic myelogenous leukemia

We report on two cases, one with acute lymphoblastic leukemia and a second with lymphatic blastic phase of Philadelphia chromosome-positive chronic myelogenous leukemia, cytogenetically characterized by ider(9)(q10)t(9;22)(q34;q11). Our findings and the data of the 4 cases previously published indicate that ider(9)(q10)t(9;22)(q34;q11) represents a rare but recurrent chromosomal abnormality occurring in hematological malignancies with lymphoid differentiation, namely acute lymphoblastic leukemia and lymphatic blastic phase of chronic myelogenous leukemia, and most likely evolves from a preexistent der(9) involved in the standard t(9;22).

Detection of PML-RAR alpha fusion transcript in Ph positive leukemia with acute promyelocytic phenotype lacking the t(15;17) cytogenetic abnormality

A 39-year-old woman was diagnosed with acute promyelocytic leukemia (APL) with disseminated intravascular coagulation syndrome. The hematologic examination showed a morphologic, cytochemical, and immunophenotypic picture typical of an APL, with a marked leukocytosis and a mixed population of hypergranular and microgranular promyelocytes. The cytogenetic analysis showed a 46,XX,t(9;22) karyotype, without any alterations of chromosomes 15 and 17. The t(15;17) translocation was not evident in FISH experiments, while a molecular analysis revealed the presence of a PML-RAR alpha chimera.

Chronic myeloid leukemia presenting ALL-type BCR/ABL transcript

We investigated the breakpoints of the bcr gene in 46 Ph1-positive CML cases by Southern blot analysis of bcr rearrangement, and in 17 CML cases by a combination of Southern blot analysis and RT-PCR. By Southern blot, the breakpoint was not identified on M-bcr in three CML cases, of which one case showed the P210-type bcr/abl transcript and two cases showed the ALL-type (P190-type) bcr/abl transcript with or without P210 transcript. Later two cases showed unique hematological profiles such as thrombocytosis, mild myelofibrosis, and relative resistance to alkylating agents. Therefore, the present study suggests that expression of the P190-type transcript may affect clinical and hematological findings in CML.

Minor myeloid component in Ph chromosome-positive acute lymphoblastic leukaemia: correlation with cytogenetic pattern and implication for poor response to therapy

Morphological, immunological and cytogenetic features were studied in 27 adults presenting with Ph chromosome-positive acute lymphoblastic leukaemia (ALL), in correlation with clinical outcome. Twenty patients (group 1) were diagnosed as having typical ALL according to the FAB criteria supported by immunological findings. Less than 1% blast cells with azurophilic granules were detected in all cases. Myeloid cytochemistry, i.e. peroxidase and Sudan black-B stain, was negative in all cases. A minor phenotype deviation consisting of the expression of the CD13 myeloid-associated marker was detected in two patients. In seven patients (group 2) a diagnosis of ALL with a minor myeloid component was made because of the presence of a majority of lymphoid blasts and of 5-15% blast cells with morphological cytochemical and immunological features of the myeloid lineage. Abnormal metaphases were found in 6/20 (30%) patients in group 1, compared with 7/7 (100%) patients in group 2. All patients were treated by antilymphoid regimens; however, complete remission was achieved in 17/20 (85%) patients in group 1 versus 1/7 (14.3%) patients in group 2. Median survival was 16 months, range < 1-120+ in group 1 and 9 months, range < 1-15 in group 2. It is concluded that morphological, immunological and cytogenetic studies allow for the recognition of two cytological subsets of Ph+ ALL. The presence of a minor myeloid component in otherwise typical Ph chromosome-positive ALL may be associated with a distinct cytogenetic pattern and poor responses to antilymphoid therapy.

Acute lymphoblastic leukaemia in the elderly

Acute lymphoblastic leukaemia (ALL) is rare in adults over the age of 60 years, with an incidence of 1 per 100,000 per year. We review the current (sparse) literature and our Regional experience of 62 consecutive cases of ALL in this age group collected over a ten year period. The patterns of cytogenetic abnormalities and immunophenotypes differs from those seen in ALL in childhood and young adults, but are similar to those reported in previous studies. B-ALL was found at twice the rate observed in younger adults (9/51 versus 6/99) and T-ALL was rare (2/51). In our patients we had few cytogenetic results but in the literature up to 50% of patients have been found to be Philadelphia positive, supporting the hypothesis that ALL in this group is often a stem cell disorder. In our patients treatment results were disappointing, with only 30% of those given 'curative' treatment achieving a complete remission, and a relapse rate of 92%, mirroring other published series. The overall four year survival was 4%. We conclude that ALL in the elderly is a rare condition with an extremely poor prognosis. Aggressive treatment may prolong life but it seldom cures.

Late-appearing Philadelphia chromosome in a patient with acute nonlymphocytic leukaemia derived from myelodysplastic syndrome: detection of P210- and P190-type bcr/abl fusion gene transcripts at the leukaemic stage

We describe a patient with acute nonlymphocytic leukaemia (ANLL) derived from myelodysplastic syndrome in whom the Philadelphia chromosome (Ph1) first emerged at the late stage of ANLL transformation. Cytogenetically, the Ph1 chromosome was not detected until the late stage of ANLL transformation, 14 months after the transformation following a 3-month history of refractory anaemia with excess of blasts. The cells with and without the Ph1 chromosome had a common abnormal chromosome, t(3;3) (q21;q26). The reverse transcription-polymerase chain reaction analysis showed no bcr/abl message at diagnosis. However, the mRNA encoding P210bcr/abl was detected in the early stage of ANLL transformation. Furthermore, the mRNAs encoding both P210bcr/abl and P190bcr/abl were detected in the late stage of ANLL transformation when the Ph1 chromosome was detected by cytogenetic analysis. These evidences support a multistep pathogenesis of leukaemias, and the products of bcr/abl fusion gene may influence the course of disease.

Orbito-ocular granulocytic sarcoma (OOGS) and acute myeloblastic leukemia (AML) with duplication of Philadelphia chromosome

A 6-year-old Turkish boy with bilateral orbito-ocular granulocytic sarcoma and AML is described. Cytogenetic studies on peripheral blood disclosed an abnormal hyperdiploid population with a double Ph chromosome. Despite intensive chemotherapy, he achieved only partial remission. Repeated cytogenetic studies on bone marrow during relapse revealed the persistence of double Ph chromosome. The aggressive course and the short survival time of this patient, despite adequate chemo-radiotherapy, may be explained by the presence of the double Ph chromosome.

B-lymphoid/myeloid stem cell origin in Ph-positive acute leukemia with myeloid markers

We report two cases of Philadelphia chromosome (Ph)-positive acute leukemia with definite myeloid markers. Ph was the sole chromosomal abnormality at presentation, and neither eosinophilia, basophilia, thrombocytosis nor hepatosplenomegaly was present. In both cases, Ph+ myeloblasts showed positive stain for myeloperoxidase and naphthol ASD chloroacetate esterase, which fulfilled the FAB criteria of acute myelogenous leukemia (AML). Ph+ myeloblasts co-expressed myeloid and B-lymphoid antigens (CD10, CD13, CD19 and CD33). In case 1, myeloblasts rearranged M-BCR, and the expression of M-BCR/ABL chimeric RNA was demonstrated by using the reverse transcription polymerase chain reaction (RT-PCR). They also clonally rearranged IGH. Ph clone disappeared on cytogenetic analysis in remission, and granulocytes in remission did not have rearranged M-BCR. In case 2, morphocytochemically distinct myeloid and lymphoid blast populations were seen. Myeloblasts and lymphoblasts were enriched > 96% as CD19-/CD33+ and CD19+/CD33- populations, respectively. Both of them possessed the identical rearrangement of IGH and M-BCR, indicating a common leukemic progenitor cell origin. Furthermore, m-BCR/ABL was detected in addition to M-BCR/ABL on RT-PCR. Accordingly, both cases were diagnosed as de novo Ph+ acute leukemia rather than as chronic myelogenous leukemia in blastic crisis. Their mixed B-lymphoid/myeloid characteristics strongly suggest that so-called 'Ph+ AML' is derived from Ph+ myeloid/B-lymphoid stem cells.

Differences between blastic chronic myeloid leukemia and Ph-positive acute leukemia

Cytogenetic and molecular characteristics of chronic myeloid leukemia in blast crisis and Ph-positive acute leukemia are compared. The main differences relate to the presence of Ph-negative metaphases at diagnosis and the disappearance of Ph in complete remission in acute leukemia, and the localization of the chromosome breakpoints in the BCR gene, in the bcr segment in chronic leukemia and in the first intron of the BCR gene in 50% of acute leukemias. The profiles of these abnormalities, as well as the types of additional chromosome changes, are not sufficient to distinguish between the two disorders in every patient. The distinction between these two entities, which is possible in the majority of patients, will be improved by results of experimental work currently in progress in many laboratories.

Therapy for Philadelphia chromosome-positive acute lymphoblastic leukemia: possible use of interferon on the basis of some novel concepts

Current understanding of molecular genetics enables the establishment of new categories based on pathogenesis. Philadelphia (Ph) chromosome-positive leukemia has been reclassified into two molecularly distinct subsets, and the leukemogenesis at the cell level might be linked to the molecular changes. Therefore, treatment for leukemia patients with Ph chromosome could be based on the molecular characteristics. In this review, we discuss the strategy of treating patients with Ph-positive acute lymphoblastic leukemia and the benefit of the combined modality of interferon and chemotherapy.

Cytogenetic abnormalities in childhood acute lymphoblastic leukemia correlates with clinical features and treatment outcome

Virtually all cases of childhood acute lymphoblastic leukemia have chromosomal abnormalities. Non-random chromosomal abnormalities have been correlated with leukemic cell lineage, the degree of cell differentiation and certain clinical and biologic features. Cytogenetic findings have prognostic significance, but the adverse influence of many rearrangements, including most chromosomal translocations, may be offset by the greater cytoreductive effects of intensified therapy. Cytogenetic abnormalities have also provided focus for molecular studies of leukemogenesis. Such studies have recently identified key genes and their protein products which play important roles in malignant transformation and proliferation.

Quantitative acute leukemia cytogenetics

Using literature data on cytogenetic abnormalities in 3,612 cases of acute myeloid leukemia (AML) and 1,551-cases of acute lymphocytic leukemia (ALL), we have attempted to quantify the information value of finding the typical ALL- and AML-associated chromosome aberrations. Sensitivity, specificity, and predictive value of finding or not finding a given aberration were calculated for several diagnostic scenarios: for the differential diagnosis between ALL and AML when the patient is known to have acute leukemia, for the differential diagnosis among AML FAB subtypes in a patient with known AML, and for the differential diagnosis between ALL FAB subtypes in a patient with known ALL. The specificities were generally high, close to 1. The highest sensitivities in AML were found for +8, t(15;17)(q22;q11), t(8;21)(q22;q22), and -7 (all greater than 0.1), and in ALL for t(9;22)(q34;q11), t(4;11)(q21;q23), and +21 (again all greater than 0.1). In the AML subtypes, the highest sensitivities were 0.89 for t(15;17)(q22;q11) in M3, followed by 0.40 for t(8;21)(q22;q22) in M2, 0.30 for inv(16)(p13q22)/del(16)(q22)/t(16;16)(p13;q22) in M4, and 0.16 for t(9;11)(p21;q23) in M5. In the ALL subtypes, the highest sensitivities were 0.71 and 0.11 for t(8;14)(q24;q32) and t(8;22)(q24;q11), respectively, in L3, 0.23 for t(9;22)(q34;q11) in L2, and 0.18 and 0.13 for +21 and t(4;11)(q21;q23), respectively, in L1. The highest (1.0) positive predictive values in the AML versus ALL comparison were found for t(1;3)(p36;q21), inv(3)(q21q26), t(6;9)(p23;q34), t(7;11)(p15;p15), t(8;16)(p11;p13), t(8;21)(q22;q22), t(15;17)(q22;q11), and, as sole anomalies, for +4, +9, and +11. In the reverse comparison, ALL versus AML, positive predictive values of 1.0 were found for t(1;14)(p32-34;q11), dup(I)(q12-21q31-32), t(2;8)(p12;q24), t(8;14)(q24;q32), t/dic(9;12)(p11-12;p11-13), t(10;14)(q24;q11), and t(11;14)(p13;q11). Among the AML subgroups, the highest predictive values were: 1.0 for M3 if t(15;17), 0.91 for M2 if t(8;21), 0.86 for M4 if inv/del(16)/t(16;16), and 0.82 for M5 if t(9;11). Among the ALL subtypes, positive predictive values of greater than 0.8 were reached only for the L3-associated aberrations t(2;8) (1.0), t(8;14) (0.95), t(8;22) (0.87), and dup(I) (0.80). The highest negative predictive values were in AML 0.98 that the disease is not M3 if t(15;17) is not found, and in ALL 0.96 that the patient does not have L3 if a t(8;14) is not detected.

Inversion of chromosome 16 with the Philadelphia chromosome in acute myelomonocytic leukemia with eosinophilia. Report of two cases

Two cases are described with the rare combination of inv(16)(p13q22), strongly associated with acute myelomonocytic leukemia with eosinophilia, M4Eo, and the Philadelphia translocation, t(9;22)(q34;q11), hallmark of chronic myeloid leukemia (CML) and rarely found, (less than 1%), in acute nonlymphocytic leukemia. The patients were: case 1, a 9-year-old girl presenting with a white blood cell count (WBC) 42 x 10(9)/L with 32% blasts and bone marrow with blasts and eosinophil precursors consistent with M4Eo, and case 2, a 25-year-old man with WBC 34.7 x 10(9)/L with 13% blasts and bone marrow with features of M4Eo and basophilia. Both patients achieved remission but died following bone marrow transplantation in first remission (case 1) or in relapse (case 2). Cytogenetic findings were: case 1, at diagnosis, 46,XX,inv(16)(p13q22)(21)/46,XX,t(9;22) (q34;q11),inv(16)(8)/46,XX(10), and case 2, at diagnosis, 46,XY,t(9;22) (q34;q11),inv(16)(p13q22) (16) and in remission, 46,XY,t(9;22)(q34;q11) (1)/46,XY (24). Investigation of the breakpoint on 22 in case 1 with Southern blotting and the polymerase chain reaction demonstrated the presence of a p190 mRNA and a breakpoint typical of acute leukemia. Thus a diagnosis of M4Eo was supported by clinical and cytogenetic sequelae in each case; the Ph in case 1 was apparently secondary to inv(16), in case 2 the Ph probably preceded inv(16) in the etiology of the leukemia.

Detection of chimeric BCR-ABL genes in acute lymphoblastic leukaemia by the polymerase chain reaction

Philadelphia chromosome-positive acute lymphoblastic leukaemia (ALL) is most common in adults and is associated with poor prognosis. Since karyotypic identification of the Philadelphia translocation has been hampered by technical difficulties, we used the polymerase chain reaction (PCR) to look for the BCR-ABL rearrangement in stored samples from a selected group of 314 German ALL patients. BCR-ABL transcripts were found in 77 of 179 adults and were restricted to those with B-precursor leukaemias. 55% of adult common ALL patients had BCR-ABL and its presence correlated with poor overall survival and remission duration. Of 135 children with common ALL, 5 (6%) primary cases and 8 (17%) with recurrent neoplasias were PCR-positive. We recommend prospective evaluation of BCR-ABL analysis with PCR in patients with a B-precursor leukaemia.