Leukemia cell lines: in vitro models for the study of Philadelphia chromosome-positive leukemia

The Philadelphia (Ph) chromosome, the main product of the (9;22)(q34;q11) translocation, is the cytogenetic hallmark of chronic myeloid leukemia (CML), a clonal myeloproliferative disorder of the hematopoietic stem cell; the Ph chromosome is also found in a sizeable portion of acute lymphoblastic leukemia (ALL) patients and in a small number of acute myeloid leukemia (AML) cases. At the molecular level, the t(9;22) leads to the fusion of the BCR gene (on chromosome 22) to the ABL gene (translocated from chromosome 9); this fusion gene BCR-ABL with its elevated tyrosine kinase activity must to be central to the pathogenesis of these disorders. Three different breakpoint cluster regions are discerned within the BCR gene on chromosome 22: M-bcr, m-bcr, and mu-bcr. Ph + leukemia cell lines are important tools in this research area. More than 20 ALL-and more than 40 CML-derived Ph + leukemia cell lines have been described. Furthermore, three Ph + B-lymphoblastoid cell lines, established from patients with Ph + ALL or CML, are available. Molecular analysis has documented BCR-ABL fusion genes in three apparently Ph chromosome-negative cell lines, all three derived from CML. Nearly all Ph + ALL cell lines have the m-bcr e1-a2 fusion gene (only two ALL cell lines have a b3-a2 fusion) whereas all CML cell lines, but one carry the M-bcr b2-a2, b3-a2 or both hybrids. The mu-bcr e19-a2 has been detected in one CML cell line. Four cell lines display a three-way translocation involving chromosomes 9, 22 and a third chromosome. Additional Ph chromosomes (up to five) have been found in four Ph + ALL cell lines and in 18 CML cell lines; though in some cell lines the extra Ph chromosome(s) might be caused by the polyploidy (tri- and tetraploidy) of the cells. Another modus to acquire additional copies of the BCR-ABL fusion gene is the formation of tandem repeats of the BCR-ABL hybrid as seen in CML cell line K-562. Both mechanisms, selective multiplication of the der(22) chromosome and tandem replication of the fusion gene BCR-ABL, presumably lead to enhanced levels of the fusion protein and its tyrosine kinase activity (genetic dosage effect). The availability of a panel of Ph + cell lines as highly informative leukemia models offers the unique opportunity to analyze the pathobiology of these malignancies and the role of the Ph chromosome in leukemogenesis.     

Chromosomes and causation of human cancer and leukemia. XXXII. Unusual features of Ph1-positive acute myeloblastic leukemia (AML), including a review of the literature.

Five cases of Ph1-positive AML were studied. In all cases a Ph1-chromosome was shown with banding techniques to be due to a translocation between chromosomes No. 9 and No. 22. Cases 1 and 4 were found to have more than one Ph1 with evidence of only on Ph1-translocation accompanying other chromosome abnormalities. Two cases represented an unusual pattern of appearance and disappearance of the Ph1-positive clone during their clinical courses: Case No. 2 was originally Ph1-positive (46,XY,Ph1) but two months before his expiration the Ph1-positive clone was completely replaced by a newly developed Ph1-negative clone with an abnormal chromosome No. 21 (46,XY,21q+), whereas case No. 3, primarily Ph1-negative, developed a Ph1-positive clone among the previously karyotypically normal cells one month before death. The Ph1-positive AML cases presented have been discussed in relation to: 1) the genesis and significance of the Ph1-positive clone, 2) differentiation from the blastic phase of CML and 31 the general experience with Ph1-positive acute non-lymphocytic leukemia (ANLL), the world literature of which have been tabulated.     

Cytogenetic study of a new Ph1-positive cell line (NALM-1).

The chromosomes of a cell line (NALM-1) derived from the leukocytes of a patient with chronic myelocytic leukemia (CML) were examined with several banding techniques. The modal chromosome number was 46 and the cells contained a Philadelphia chromosome (Ph1), due to the standard translocation of the missing segment of the long arm of chromosome No. 22 onto the distal end of the long arm of chromosome No. 9, i.e., t(9;22) (q34;q11). The Ph1-positive modal cells of the NALM-1 line also had two common marker chromosomes, an extra X-chromosome, and missing chromosomes in groups No. 7, 9, and 15. Immunologic examination of the NALM-1 cells revealed them to have non-T-non-B (null) surface characteristics. An antigen specific for cells of acute leukemia and a human la-like antigen were detected. These facts suggested that the NALM-1 cell line originated from CML cells and maintained the cytogenetic and Immunologic characteristics of such cells.     

成人急性B淋巴细胞白血病核型t(9;22)易位与免疫表型关系探讨

目的 探讨成人急性B淋巴细胞白血病(B-ALL)染色体t(9;22)易住与免疫表型之间的关系。方法 对154例初治成人B-ALL进行形态学(M)免疫学(I)和细胞遗传学(C)分型。结果 发现有t(9;22)易位(Ph^ )的B-ALL占46例(29．9％),其中伴髓系抗原(CD13或CD33表达(My^ )有28例(60．9％),伴T细胞抗原(CD2或CD3或CD33)表达(T细胞抗原阳性)3例(6．5％),cd34^ 39例(84．8％),CD10^ 45例(97．8％)。经分析发现,Ph^ 与My^ 高度相关,而与T细胞抗原和CD34^ 无相关。结论 伴髓系抗原表达的成人B-ALL与核型t(9;22)易位密切相关。这可能是影响成人My^ B-ALL缓解率低,持续缓解时间短,预后差的原因之一。     

Acute myeloid leukemia developing during imatinib mesylate therapy for chronic myeloid leukemia in the absence of new cytogenetic abnormalities

The BCR/ABL tyrosine kinase inhibitor imatinib mesylate produces a high rate of cytogenetic responses in patients with Philadelphia (Ph)-positive chronic myeloid leukemia (CML), but secondary clonal chromosome abnormalities may develop in Ph-negative cells, and acute myeloid leukemia (AML) has been reported in patients with secondary chromosome abnormalities. We report a patient who developed AML during imatinib treatment of Ph-positive CML despite a cytogenetic response and absence of secondary chromosome abnormalities. Thus, development of AML as a rare event in CML patients with cytogenetic responses to imatinib therapy does not depend on the development of secondary cytogenetic abnormalities.     

Detection of cytogenetic aberrations both in CD90 (Thy-1)-positive and (Thy-1)-negative stem cell (CD34) subfractions of patients with acute and chronic myeloid leukemias.

Acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) are thought to arise from malignant hematopoietic progenitor cells representing early and undifferentiated stem cell clones. In CML there is evidence for a progenitor cell subset free of leukemic clones, depending on the course of the disease. Additionally, it has been suggested that in AML, the early stem cell compartment (CD34+/90+) does not harbor the malignant clone. We analyzed white blood cells from leukemia patients for the presence of aberrant cells in stem cell subfractions. Sixteen patients with CML, six patients with AML, two patients with acute lymphatic leukemia (ALL) and one with chronic myelomonocytic leukemia (CMMOL), all with known cytogenetic abnormalities, were evaluated according to their CD90 (Thy-1)-positive or -negative phenotype. Subsets were sorted on to slides and further characterized by FISH and/or standard cytogenetic testing. The bcr-abl translocation or gross chromosomal abnormalities could be detected in equally high amounts of 92.2% and 89.2% in both stem cell subsets. We conclude, that in progressed AML and CML cells characterized by specific genetic aberrations implicated in the malignant state can be found in the CD34+/CD90+ and CD90- population, thus making CD90 an inappropriate marker to distinguish benign from malignant cells in these leukemias.     

Philadelphia chromosome-positive acute lymphoblastic leukemia cell lines without classical breakpoint cluster region rearrangement

The Philadelphia (Ph) chromosome translocation which is classically observed in chronic myeloid leukemia (CML) is sporadically found in acute lymphoblastic leukemia (ALL). In CML the translocation breakpoint on chromosome 22 is within the breakpoint cluster region, while in childhood ALL, no detectable change in breakpoint cluster region is routinely observed. In order to investigate the nature of this difference, we have established and characterized two cell lines from a child with Ph positive ALL. The cell lines have retained the cytochemical staining pattern, enzyme activity, monoclonal antibody profile, and immunoglobulin gene rearrangements of the child's malignant cells. The cell lines had the same Ph translocation t(9;22) (q34;q11) as the child's malignant cells along with additional chromosome changes. Southern blot analysis showed that the Ph translocation did not involve the 5.8-kilobase breakpoint cluster region segment characteristically seen in CML. The cell lines reported here will be a valuable resource in ascertaining the biological significance of the Ph translocation seen in ALL.     

Characterization of the translocation breakpoint in a patient with Philadelphia positive, bcr negative acute lymphoblastic leukaemia

Approximately 5% of children and 10-20% of adults with acute lymphoblastic leukaemia (ALL) have a chromosome translocation t(9;22) which at the cytogenetic level appears identical to that in chronic myeloid leukaemia (CML). The t(9;22) translocation was first recognised in CML patients by its 22q- or Philadelphia (Ph) chromosome. While all Ph positive CML patients so far described have a chromosome 22 breakpoint within the breakpoint cluster region (bcr) located in the 3' part of the phl gene, only some Ph positive ALL patients have breakpoints in bcr. We have cloned the breakpoint of the 9q+ chromosome from the DNA of a Ph positive ALL patient in whom there is no breakpoint in the bcr. The non-chromosome 9 sequences of the breakpoint region are shown to be derived from chromosome 22. The breakpoint in chromosome 22 is shown to be the first intron of the phl gene about 66kb upstream of the bcr. Using probes from this intron, rearrangements were detected in the DNA of two out of twelve additional Ph positive, bcr negative ALL patients.     

The chromosomes and causation of human cancer and leukemia. XVIII. The missing Y in acute myeloblastic leukemia (AML) and Ph1-positive chronic myelocytic leukemia (CML).

The occurrence of a missing Y chromosome was investigated in the bone marrow cells of male individuals, i.e., 255 controls, 73 with acute myelocytic leukemia (AML) and 59 with Ph1-positive chronic myelocytic leukemia (CML). The incidence in controls of individuals with 45,X cells increased with age, particularly after the age of 60. In AML, 45,X metaphases were detected in two patients over 70 years of age, but the leukemia seemed to have involved the 46,XY cells rather than the 45,X cells. Four of the six patients with No. 8-No. 21 translocation and two of the 16 with major karyotypic abnormalities (MAKA) exhibited a missing Y in the leukemic cells in addition to other karyotypic aberrations. Four of the Ph1-positive CML patients exhibited a missing Y in all or nearly all the cells in the bone marrow along with the Ph1. In one patient, additional chromosome abnormalities involved the 46,XY,Ph1 rather than the 45,X,Ph1 cells. The genesis of the missing Y in CML cells may be related to the presence of the Ph1, though apparently the patient's age also plays a role. It is our hypothesis that 45,X or 45,X,Ph1 cells are resistant to the development of further chromosomal abnormalities and, thus, reflect their resistance to being involved in an acute leukemic process.     

Detection of BCR/ABL Fusion Gene by Hematological and Cytogenetical Analysis in Chronic Myeloid Leukemia Patients in Quetta,Pakistan

Background: Chronic myeloid leukemia (CML) is a myeloproliferative disorder of pluripotent stem cells,caused by reciprocal translocation between the long arms of chromosomes 9 and 22, t(9;22)(q34;q11), known asthe Philadelphia chromosome. Materials and Methods: A total of 51 CML patients were recruited in this study.Complete blood counts of all CML patients were performed to find out their total leukocytes, hemoglobin andplatelets. FISH was performed for the detection of BCR-ABL fusion and cryptogenic tests using bone marrowsamples were performed for the conformation of Ph (9;22)(q34;q11) and variant translocation mechanisms.Results: In cytogenetic analysis we observed that out of 51 CML patients 40 (88.9%) were Ph positive and 4(8.88%) had Ph negative chromosomes. Mean values of WBC 134.5 103/μl, hemoglobin 10.44 mg/dl, and platelets288.6 103/μl were observed in this study. Conclusions: In this study, Ph positive translocation between chromosome(9:22)(q34;q11) were observed in 40 (88.9%) CML patients.     

Direct and serial transplantation of Ph1-positive acute lymphoblastic leukemia into nude mice

A new Philadelphia chromosome (Ph1-positive) acute lymphoblastic leukemia (ALL) cell line was established in nude mice by direct and serial transplantation of peripheral blood leukemia cells from an adult patient. Although the patient's leukemia cells did not grow in vitro, they were successfully transplanted for 8 serial passages, giving rise to progressive growth of tumors with frequent involvement of lymph nodes, liver, spleen, bone marrow, and meninges. The tumor cells could also be passaged in an ascites form. This in vivo cell line, designated PALL-I, retained the Ph1 chromosome, t(9;22) (q34;q11), and pre-B-cell phenotype (SmIg-, CpIg-, CD10+, CD19+, OKIaI+, and CD38+), like the original leukemia cells. Molecular genetic analysis of PALL-I cells revealed neither bcr rearrangement nor 8.5-kb abI-related mRNA that is characteristically seen in Ph1-positive chronic myelogenous leukemia (CML). Thus, the PALL-I cell line is genetically distinct from CML. It may provide a useful model for an understanding of the cellular and molecular biology of Ph1-positive ALL without classical bcr rearrangement.     

Clonally unrelated BCR-ABL-negative acute myeloblastic leukemia masquerading as blast crisis after busulphan and interferon therapy for BCR-ABL-positive chronic myeloid leukemia.

We report a patient with Philadelphia (Ph)-positive, BCR-ABL rearrangement positive, chronic myeloid leukemia (CML) with a prolonged chronic phase of 24 years who was first prescribed alpha-2 interferon 22 years after initial diagnosis. This therapy was tolerated poorly on account of thrombocytopenia, but an eventual major cytogenetic response was followed soon afterwards by transformation to terminal acute myeloid leukemia (AML). Cytogenetic studies indicated that the transformed myeloblasts were karyotypically normal and Ph negative. Although polymerase chain reaction (PCR) analysis of total leukemic mRNA remained BCR-ABL positive, other molecular studies, including Southern blotting and fluorescent in situ hybridization (FISH) analyses, showed that myeloblasts were BCR-ABL rearrangement negative. PCR-based clonality studies using an X-chromosome-linked restriction fragment polymorphism within the phosphoglycerate kinase gene (PGK1) further showed that the Ph-negative blast cells had a different clonal origin from the Ph-positive clone of chronic phase. We suggest that cases of underlying Ph-negative leukemic transformation in Ph-positive CML warrant further study and should be considered for trial of intensive remission induction therapy as appropriate for acute leukemia.     

Recurrent isochromosome 21 and multiple abnormalities in a patient suspected of having acute myeloid leukemia with eosinophilic differentiation—a rare case from South India

Acute myeloid leukemia (AML) is a phenotypically heterogeneous disorder. The M4 subtype of AML is frequently associated with the cytogenetic marker inversion 16 and/or the presence of eosinophilia. Blast crisis is the aggressive phase of the triphasic chronic myeloid leukemia (CML), which is a disease with Philadelphia (Ph) chromosome as the major abnormality. In the present study, we report a 76-year-old patient suspected of having AML with eosinophilic differentiation (AML-M4), which in clinical tests resembles CML blast crisis with multiple chromosomal abnormalities. Isochromosome 21 [i(21)(q10)] was the most recurrent feature noted in metaphases with 46 chromosomes. Ring chromosome, tetraploid endoreduplication, recurrent aneuploid clones with loss of X chromosome, monosomy 17, monosomy 7, and structural variation translocation (9;14) were also observed in this patient. Fluorescent in situ hybridization (FISH) confirmed the absence of Ph chromosome. This report shows how cytogenetic analyses revealed atypical structural aberrations in the M4 subtype of AML.     

Long-Term Outcome of Philadelphia Chromosome Positive Leukemia From Eastern Indian Subcontinent: An Experience in the Era of Tyrosine Kinase Inhibitor (TKI) Therapy

IntroductionPhiladelphia chromosome (Ph) marks a group of leukemia with almost all cases of chronic myeloid leukemia (CML), a subset of acute lymphoid leukemia (ALL) and rare cases of acute myeloid leukemia (AML). In the era of precision medicine, such cases are successfully managed with tyrosine kinase inhibitor (TKI) drugs. This study examined the features and long-term outcome of Ph+ve cases from a tertiary cancer care center from Eastern Indian subcontinent.Materials and MethodsReviewing retrospective case-records registered between 2005 and 2015, cases of CML and ALL were documented under Ph+ve category; while no instance of Ph+ve AML was found.ResultsIn CML cohort, adult and juvenile incidences were 95.2% and 4.8% respectively; in ALL cohort, the same was found for 66.67% and 33.33% cases. Among the CML cases, 10-year overall survival (OS) and progression-free survival (PFS) were significantly affected upon the phase of disease at time of detection. Furthermore, both OS and PFS significantly dropped whenever non-TKI-based treatment was applied prior to TKI-commencement. Long-term (10-year) sensitivity to 1st generation TKI, imatinib, was noted 88.51% and 83.33% for adult and juvenile CML cohorts, respectively. For Ph+ ALL cohort, the OS was benefitted upon combinatorial TKI and chemotherapy. However, large fractions of affected individual from CML as well as ALL cohorts were found to discontinue follow-up.ConclusionTogether with differences in outcome on the basis of drug-use from onset, age (juvenile versus adult) and stage at diagnosis, our analyses bring forward the real-world scenario of Ph+ve leukemia managed with precision medicine.     

Chromosomes and causation of human cancer and leukemia. XXIX. Further studies on karyotypic progression in CML.

Fifty-seven Ph1-positive cases of chronic myelocytic leukemia (CML) were analyzed with chromosomal banding techniques and their karyotypic progression followed. These cases included 1 without evidence of a Ph1-translocation and 1 new patient with a complex Ph1-translocation involving chromosomes No. 9, No. 17 and No. 22. Of the 57 patients, 28 had the Ph1 as the only karyotypic anomaly, whereas the remaining 29 cases developed and/or were associated with chromosomal changes usually of a hyperdiploid nature, particularly in the blastic phase, in addition to the Ph1. Even though the additional karyotypic changes frequently included chromosomes No. 8, No. 17, No. 19 and No. 21, a large number of others was also involved, although less often. The series included 3 cases with different types of translocations unrelated to the Ph1. The cytogenetic observations have been correlated with some of the clinical parameters. The survival of the patients was evaluated in relation to the karyotypic findings, indicating that the chromosomal changes may not play as important a role in the prognostic and progressive aspects of Ph1-positive CML as that of other as yet undetermined factors.     

Quantification by DNA-based cytophotometry of the 9q+/22q-chromosomal translocation associated with chronic myelogenous leukemia.

DNA-based cytophotometry was used to analyze metaphase chromosomes in four patients with chronic myelogenous leukemia. In three of these patients, both Philadelphia chromosome (Ph1)-positive and Ph1-negative cells were measured. On the basis of these three patients, the characteristic 9q+/22q- translocation of chronic myelogenous leukemia involves the net transfer of 0.325% of the autosomal genome; there is no evidence of net gain or loss of DNA (apart from duplication of the Ph1 chromosome in one patient), and no significant difference is found in the amount of DNA transferred in different patients. Significant differences are found among patients in the derived Chromosomes 9 and the Ph1 chromosomes and are ascribed to preexisting variations in the Ph1-negative cells of these patients. There is no evidence in these patients of any further cytogenetic lesion associated with chronic myelogenous leukemia.     

Sprycel for chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia resistant to or intolerant of imatinib mesylate.

PURPOSE: On June 28, 2006, the U.S. Food and Drug Administration approved dasatinib (Sprycel; Bristol-Myers Squibb), a new small-molecule inhibitor of multiple tyrosine kinases, for the treatment of adults with chronic phase, accelerated phase, or myeloid or lymphoid blast phase chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) with resistance or intolerance to prior therapy including imatinib. This summary reviews the database supporting this approval. EXPERIMENTAL DESIGN: Four single-arm multicenter studies supported the efficacy and safety of dasatinib. The primary efficacy end point in chronic phase CML was major cytogenetic response. The primary end point in accelerated phase, myeloid phase, and lymphoid blast phase CML, and Ph(+) ALL was major hematologic response. RESULTS: The four studies combined enrolled 445 patients. In patients with chronic phase CML, the major cytogenetic response rate was 45% with a complete cytogenetic response rate of 33%. Major hematologic response rates in patients with accelerated phase CML, myeloid CML, lymphoid blast CML, and Ph(+) ALL were 59%, 32%, 31%, and 42%, respectively. Median response durations in chronic phase, accelerated phase, and myeloid phase CML had not been reached. The median durations of major hematologic response were 3.7 months in lymphoid blast CML and 4.8 months in Ph(+) ALL. Common toxicities with dasatinib included myelosuppression, bleeding, and fluid retention. CONCLUSIONS: This report describes the Food and Drug Administration review supporting the approval of dasatinib for CML and Ph(+) ALL based on the rates and durability of cytogenetic and hematologic responses.