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PubMed2006

Allogeneic stem cell transplantation for patients with chronic myeloid leukemia and acute lymphocytic leukemia after Bcr-Abl kinase mutation-related imatinib failure.

Resistance to imatinib mesylate is an emerging problem in the treatment of chronic myeloid leukemia (CML), often associated with point mutations in the Bcr-Abl kinase domain. Outcome of patients with such mutations after allogeneic stem cell transplantation (Allo-SCT) is unknown. Ten imatinib-resistant patients with Bcr-Abl kinase mutations received a transplant: 9 had CML (3 in chronic phase, 4 in accelerated phase, and 2 in blast phase) and 1 had Philadelphia-positive acute lymphocytic leukemia (ALL). Patients harbored 9 different protein kinase mutations (T315I mutation, n = 2). Preparative regimens were ablative (n = 7) and nonablative (n = 3). All patients engrafted; there were no treatment-related deaths. Disease response was complete molecular (CMR; n = 7), major molecular (n = 2), and no response (n = 1). Three patients (mutations Q252H, E255K, and T315I) died of relapse after Allo-SCT. Seven patients are alive (6 in CMR) for a median of 19 months. Allo-SCT remains an important salvage option for patients who develop resistance to imatinib through Bcr-Abl mutations.

Adult↗
PubMed2006

INNO-406, a novel BCR-ABL/Lyn dual tyrosine kinase inhibitor, suppresses the growth of Ph+ leukemia cells in the central nervous system, and cyclosporine A augments its in vivo activity.

Central nervous system (CNS) relapse accompanying the prolonged administration of imatinib mesylate has recently become apparent as an impediment to the therapy of Philadelphia chromosome-positive (Ph+) leukemia. CNS relapse may be explained by limited penetration of imatinib mesylate into the cerebrospinal fluid because of the presence of P-glycoprotein at the blood-brain barrier. To overcome imatinib mesylate-resistance mechanisms such as bcr-abl amplification, mutations within the ABL kinase domain, and activation of Lyn, we developed a dual BCR-ABL/Lyn inhibitor, INNO-406 (formerly NS-187), which is 25 to 55 times more potent than imatinib mesylate in vitro and at least 10 times more potent in vivo. The aim of this study was to investigate the efficacy of INNO-406 in treating CNS Ph+ leukemia. We found that INNO-406, like imatinib mesylate, is a substrate for P-glycoprotein. The concentrations of INNO-406 in the CNS were about 10% of those in the plasma. However, this residual concentration was enough to inhibit the growth of Ph+ leukemic cells which expressed not only wild-type but also mutated BCR-ABL in the murine CNS. Furthermore, cyclosporine A, a P-glycoprotein inhibitor, augmented the in vivo activity of INNO-406 against CNS Ph+ leukemia. These findings indicate that INNO-406 is a promising agent for the treatment of CNS Ph+ leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

Durable responses to imatinib in patients with PDGFRB fusion gene-positive and BCR-ABL-negative chronic myeloproliferative disorders.

Fusion genes derived from the platelet-derived growth factor receptor beta (PDGFRB) or alpha (PDGFRA) play an important role in the pathogenesis of BCR-ABL-negative chronic myeloproliferative disorders (CMPDs). These fusion genes encode constitutively activated receptor tyrosine kinases that can be inhibited by imatinib. Twelve patients with BCR-ABL-negative CMPDs and reciprocal translocations involving PDGFRB received imatinib for a median of 47 months (range, 0.1-60 months). Eleven had prompt responses with normalization of peripheral-blood cell counts and disappearance of eosinophilia; 10 had complete resolution of cytogenetic abnormalities and decrease or disappearance of fusion transcripts as measured by reverse transcriptase-polymerase chain reaction (RT-PCR). Updates were sought from 8 further patients previously described in the literature; prompt responses were described in 7 and persist in 6. Our data show that durable hematologic and cytogenetic responses are achieved with imatinib in patients with PDGFRB fusion-positive, BCR-ABL-negative CMPDs.

Adult↗
PubMed2006

MK-0457, a novel kinase inhibitor, is active in patients with chronic myeloid leukemia or acute lymphocytic leukemia with the T315I BCR-ABL mutation.

MK-0457 (VX-680) is a small-molecule aurora kinase (AK) inhibitor with preclinical antileukemia activity. The T315I BCR-ABL mutation mediates resistance to imatinib, nilotinib, and dasatinib. MK-0457 has in vitro activity against cells expressing wild-type or mutated BCR-ABL, including the T315I BCR-ABL mutation. Three patients with T315I abl-mutated chronic myeloid leukemia (CML) or Philadelphia chromosome (Ph)-positive acute lymphocytic leukemia (ALL) have achieved clinical responses to doses of MK-04547 that are not associated with adverse events. Higher MK-0457 dose levels were associated with clinical responses and down-regulation of CrkL phosphorylation in leukemia cells. The possible role of AK inhibition in these clinical responses requires further investigation. The currently reported cases are the first observed clinical activity of a kinase inhibitor against the T315I phenotype. The observation of responses in 3 patients with T315I phenotype-refractory CML or Ph-positive ALL, at doses of MK-0457 associated with no significant extramedullary toxicity, is very encouraging.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Direct evidence that leukemic cells present HLA-associated immunogenic peptides derived from the BCR-ABL b3a2 fusion protein.

The BCR-ABL oncogene is central in the pathogenesis of chronic myeloid leukemia (CML). Here, tandem nanospray mass spectrometry was used to demonstrate cell surface HLA-associated expression of the BCR-ABL peptide KQSSKALQR on class I-negative CML cells transfected with HLA-A*0301, and on primary CML cells from HLA-A3-positive patients. These patients mounted a cytotoxic T-lymphocyte response to KQSSKALQR that also killed autologous CML cells, and tetramer staining demonstrated the presence of circulating KQSSKALQR-specific T cells. The findings are the first demonstration that CML cells express HLA-associated leukemia-specific immunogenic peptides and provide a sound basis for immunization studies against BCR-ABL.

Adult↗
PubMed2003

Imatinib restores expression of CD62L in BCR-ABL-positive cells.

Chronic myelogenous leukemia (CML) is characterized by aberrant trafficking of malignant hematopoietic progenitor cells in the peripheral blood. Expression of the cell adhesion molecule CD62L was reported to be significantly lower in CML patients than in normal controls. We studied whether the transcription of CD62L in CML cells is dependent on the activity of the BCR-ABL tyrosine kinase. Following addition of the Abelson (ABL) tyrosine kinase inhibitor imatinib (formerly STI571) to two BCR-ABL-positive cell lines (BV173, SD-1), we observed a dose-dependent increase in CD62L RNA levels of up to 45-fold by a quantitative, real-time polymerase chain reaction and an increase in the amount of cell surface-bound CD62L of up to 18-fold by quantitative flow cytometry, respectively. These data are validated by an increased CD62L expression in the bone marrow of patients (n=6) with advanced CML who received imatinib. Restoration of defective cell adhesion mediated via the CD62L pathway may be one mechanism of action of imatinib in BCR-ABL-positive leukemias.

Antineoplastic Agents↗
PubMed2005

Fluorescence in situ hybridization monitoring of BCR-ABL-positive neutrophils in chronic-phase chronic myeloid leukemia patients during the primary stage of imatinib mesylate therapy.

We describe a method for monitoring chronic myeloid leukemia (CML) patients treated with imatinib that uses fluorescence in situ hybridization (FISH) to detect BCR-ABL in peripheral blood (PB) granulocytes. First, we compared this method, termed Neutrophil-FISH, with interphase FISH (i-FISH) analysis of bone marrow (BM), i-FISH analysis of PB mononuclear cells, and conventional cytogenetic analysis (CCA) of BM in 30 consecutive CML patients. We found the percentage of BCR-ABL-positive neutrophils as determined by Neutrophil-FISH to correlate best with the percentage of Philadelphia chromosome-positive metaphases in the BM determined by CCA (y = 0.8818x + 5.7249; r(2) = 0.968). We then performed a serial Neutrophil-FISH study of 10 chronic-phase CML patients treated with imatinib and found that the technique could clearly separate imatinib responders from nonresponders within 12 weeks of drug administration. There was a significant difference in the percentages of BCR-ABL-positive neutrophils between responder (mean 3 SD, 18.2% 3 11.8%) and nonresponder (82.4% 3 5.1%) groups at 12 weeks (P < .0001, Student t test).Together with real-time quantitative polymerase chain reaction analysis, Neutrophil-FISH represents another useful method for monitoring CML patients during the primary myelosuppressive stage of imatinib therapy because it is a quick, simple, and reliable method for assessing cytogenetic response.

Antineoplastic Agents↗
PubMed2006

Dose modification of imatinib by monitoring the level of BCR-ABL transcript in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a hematological malignancy that is characterized by the chromosome anomaly, t(9;22)(q34;q11). By this chromosomal translocation, a novel activated tyrosine kinase, BCR-ABL chimeric protein, is generated, and the protein is causative of the disease. Recently, Imatinib mesylate targeting to a BCR-ABL chimeric protein has been developed, and shown to achieve complete remission at a high rate. Patients are currently required to receive a fixed dose, 400 mg daily; however, it is possible that some of patients can maintain their remission with reduced doses of imatinib. In this study, we determined levels of BCR-ABL transcript in CML patients by real-time quantitative polymerase chain reaction analysis, and explored the possibility of individualization of therapeutic doses of imatinib. Thirty-five CML patients, including 17 newly diagnosed patients, 16 patients pre-treated with interferon-alpha, and 2 relapsed patients after allogeneic transplantation, were treated with imatinib. Complete cytogenetic response was achieved in 31 (89%) patients. Major molecular response (MMR) was achieved in 21 (60%). Complete molecular response (CMR) was achieved in 7 (20%). Imatinib was discontinued in 2 patients, one patient with MMR due to noncompliance and other patient sustaining CMR, but both patients relapsed 7 and 13 months later, respectively. The doses of imatinib were reduced in 7 patients due to its side effects, but 4 out of the 7 patients have sustained MMR, and 2 of them have sustained CMR for more than 23 months. These results indicate that some patients are able to maintain MMR with low-dose imatinib.

Adult↗
PubMed2005

Targeting the kinase activity of the BCR-ABL fusion protein in patients with chronic myeloid leukemia.

Imatinib mesylate is a major advance in the therapy of patients with chronic myelogenous leukemia (CML). Imatinib mesylate binds to the inactive conformation of BCR-ABL tyrosine kinase suppressing the Philadelphia chromosome positive clone in CML. Clinical studies have yielded impressive results in all phases of CML. With higher rates of complete cytogenetic response with imatinib, molecular monitoring of disease is now advisable in assessing response and determining prognosis. Emergence of resistance to imatinib may be manifest at the hematologic, cytogenetic, or molecular levels in patients who remain in chronic phase, or may be evidenced by the development of more advanced CML phases. Resistance and eventual clinical failure of imatinib occurs in most patients with blastic phase disease. Resistance may occur at the level of Bcr-Abl, with reduction or loss of imatinib effectiveness as a kinase inhibitor, or, despite retention of its inhibitory ability, with changes in the ability to deliver an effective dose at the cellular level, and/or, the leukemia becoming less dependent on Bcr-Abl. The various mechanisms underlying these differing, non-mutually exclusive, mechanisms of resistance must be understood to develop corresponding therapeutic remedies. We review the current data on imatinib in CML, the criteria for diagnosis of imatinib resistance, and the mechanisms that underlie such resistance in CML.

Benzamides↗
PubMed1997

Relationship between the type of BCR-ABL rearrangement and bone marrow histopathological features in chronic myeloid leukemia.

The aim of the present study was to characterize the type of BCR-ABL transcript and to correlate the molecular feature with bone marrow histology. For this purpose, we analysed the BCR-ABL rearrangement in 26 patients with chronic myeloid leukemia (CML) in the chronic phase by RT-PCR, and we also classified the bone marrow histology according to the predominance of granulocylic (GRAN) or granulocytic and megakaryocytic (GRAM/MEG) proliferation, after analysis of two independent observers. We did not find any significant difference in survival of patients presenting b2-a2 and b3-a2 transcripts or GRAN and GRAN/MEG bone marrow types, nor did we find any significant correlation of the type of BCR-ABL transcript with the bone marrow histological subgroups GRAN and GRAN-MEG (Fisher's test = 0.31). Thus, we conclude that the presence of exon b3 is not correlated to bone marrow histology in CML.

Adolescent↗
PubMed2000

Detection of BCR-ABL transcripts by multiplex and nested PCR in different haematological disorders.

Single-step Multiplex RT-PCR was used as a rapid and highly sensitive method for screening patients with myeloproliferative conditions and ALL for the presence of underlying BCR-ABL gene fusions. Positive and negative results obtained with the multiplex assay were subsequently confirmed by nested PCR. We studied 21 patients for detecting the presence of b3a2, b2a2 and e1a2 BCR-ABL transcripts at diagnosis and following treatment with different therapeutical procedures. These studies allowed the molecular characterisation of patients with different haematological disorders and for demonstrating BCR-ABL transcripts in Ph-CML. In a Ph+ CML patient, a switch of isoforms was detected after bone marrow transplantation and infusion with donor lymphocytes, implying substitution of e1a2 for b3a2 coexisting with a myeloid/lymphoid biphenotypic profile. In ALL, one Ph+ patient showed coexpression of e1a2 and b2a2 at diagnosis followed by persistence of e1a2 after bone marrow transplantation. Our results were compared to previous findings in the literature on molecular diagnosis of leukaemias.

DNA, Complementary↗
PubMed2000

Light microscopic detection of BCR-ABL transcripts after in-cell RT-PCR: fusion gene expression might correlate with clinical evolution of chronic myeloid leukemia.

A procedure for in-cell amplification of the hybrid BCR-ABL mRNA by reverse transcription and polymerase chain reaction (RT-PCR) without extraction of the nucleic acids was performed directly in fixed and permeabilized cells of leukemia patients (22 patients with Ph'-positive chronic myeloid leukaemia-CML and 1 with Ph'-positive acute leukaemia-AL, as well as 7 Ph'-negative cases) and Ph'-positive human leukaemia cell lines (K562, LAMA-84, BV173). The labelling of the amplified sequences was done employing biotinylated primers and a second PCR in a semi-nested fashion with a low number of cycles. An enzymatic system based on biotin-streptavidin-chromogen reaction was used for the detection of labeled PCR product, thus producing a coloured product, visible to the eye under a standard light microscope. All samples from patients with cytogenetic and molecular evidence of BCR-ABL rearrangement showed specific cytoplasmic staining at the site of the amplified hybrid transcripts. It allowed definite distinction between positive and negative cells. K562, LAMA-84, BV173 cells were characterized with strong diffuse staining while an interesting finding of the present study was the presence of variable quantities of colour product in patients' samples which might be due to different mRNA expression. Early and intermediate stages of myeloid maturation showed more intense reactivity. Cases with an aggressive course of accelerated or blast phase CML and AL were found to have a considerable subset of cells with strongly expressed signal while cases in chronic phase were characterised with uniform weak to moderate reaction. Our observations support the hypothesis that the amount of BCR-ABL transcript expression within neoplastic cells may play a role in dictating the eventual behaviour of the leukaemic clone. Future studies at a single cell level of larger series of consecutive cases with a follow up might be able to identify those patients who are prone to transformation and provide certain indications for further therapeutic decisions.

Adolescent↗
PubMed1999

Comparative testing of peripheral blood and bone marrow for BCR-ABL transcripts in patients post allogeneic bone marrow transplantation and during interferon treatment for chronic myeloid leukemia.

Patients with CML post allogeneic BMT or during treatment with Interferon were monitored in bone marrow and peripheral blood for BCR-ABL transcripts by RT-PCR and in the majority of cases also by Southern blotting. Bone marrow and peripheral blood samples were obtained simultaneously and tested by RT-PCR with the objective to determine the usefulness to follow CML patients by testing peripheral blood rather than bone marrow samples. For the purpose of this study we have considered the test results obtained from bone marrow samples as the standard. A total of 111 CML patients were examined who underwent either an allogeneic BMT (n=91) or were treated with Interferon (n=20) amounting to a total of 163 assessments for BCR-ABL. Concordance of results was observed in 153 samples (93.9%). 10 samples showed discordance. Seven of these were subjected to repeat testing by RT-PCR. The previously obtained discordant results were confirmed. The sensitivity of peripheral blood assays was calculated to be 96.2% with a specificity of 89.5%. RT-PCR results restricted to Southern blot negative patients showed concordance of bone marrow and peripheral blood in 91.1% of tested samples with a sensitivity of 92.7% and a specificity of 88.6%. The subset of patients in which Southern blot testing was not available showed concordance at a similar level. Complete concordance was seen in all patients that were found to be positive by Southern blotting. We conclude from this study that peripheral blood testing for BCR-ABL transcripts by RT-PCR is a test with high sensitivity and specificity and may potentially replace bone marrow testing. This approach will probably result in a high level of acceptance by patients and may permit more frequent monitoring.

Blotting, Southern↗
PubMed1999

[Molecular basis of chronic myelogenous leukemia and significance of diagnostic methods based on BCR-ABL gene amplification].

Chronic myelogenous leukemia is characterized by an abnormal 22nd chromosome known as a Philadelphia chromosome, which can be detected in 95% of patients with CML. Molecular equivalent of this aberration is a BCR-ABL translocation resulting in chimeric gene formation. A BCR-ABL chimeric gene plays a key role in the hematopoietic cells proliferation regulation. RT-PCR can be used in diagnosis of CML, to detect chimeric BCR-ABL gene, and to reveal the type of translocation what could have prognostic importance, and in monitoring of minimal residual disease, confirming the eradication of pathological cells clone after treatment and identifying the group of patients with best prognosis and best overall survival. RT-PCR in monitoring of minimal residual disease after allo- or autologous hemopoietic cells transplantation can early reveal relapse of the disease. Detection of molecular relapse is an important prognostic factor and may implicate induction of treatment which should prevent haematological relapse of the disease.

Chimera↗
PubMed2000

BCR-ABL tyrosine kinase activity regulates the expression of multiple genes implicated in the pathogenesis of chronic myeloid leukemia.

The BCR-ABL chimeric protein is thought to play a central role in the pathogenesis of Philadelphia (Ph) chromosome-positive leukemias, notably chronic myeloid leukemia (CML). There is compelling evidence that malignant transformation by BCR-ABL is critically dependent on its protein tyrosine kinase (PTK) activity. As a result, multiple signaling pathways are activated in a kinase-dependent manner, and thus the activation of such pathways may affect the expression of genes that confer the malignant phenotype. In this study, we used differential display to investigate the alterations of gene expression in BV173, a CML cell line derived from lymphoid blast crisis, after exposure to ST1571, which selectively inhibits ABL PTK activity. We show that the expression of a set of 12 genes is correlated with the kinase activity and that the profile of these genes reflects mechanisms implicated in the pathogenesis of CML. Several of the genes show a consistent pattern of altered regulation in all Ph-positive lymphoid cell lines, whereas others appear to be unique to BV173 cells. We conclude that BCR-ABL PTK activity drives the expression of specific target genes that contribute to the malignant transformation of Ph-positive cells. The identification of downstream molecules with a consistent regulation pattern may provide suitable targets for therapeutic intervention in the future.

Antineoplastic Agents↗
PubMed2000

Manifold-assisted reverse transcription-PCR with real-time detection for measurement of the BCR-ABL fusion transcript in chronic myeloid leukemia patients.

BACKGROUND: BCR-ABL fusion mRNA expression in bone marrow or peripheral blood can be used as a measure of minimal residual disease in patients with chronic myeloid leukemia (CML). METHODS: We used an oligo(dT)-coated manifold support to capture the mRNA directly from the cell lysate. After reverse transcription, the cDNA was eluted from the manifold support, and BCR-ABL and GAPDH mRNAs were quantified in real time using the TaqMan fluorogenic detection system. RESULTS: The detection limit of the method was one positive K562 cell among 10(5) negative cells. GAPDH was chosen as a reference gene based on the low variation between samples from different stages of the disease and the low signal in the absence of reverse transcription. The day-to-day variation of the method (CV) was 32%. In 43 blood samples from 13 CML patients, mRNA quantification agreed well with cytogenetic data. CONCLUSIONS: The proposed procedure constitutes a reproducible and sensitive BCR-ABL mRNA quantification method and is suitable to monitor minimal residual disease in CML patients.

Adult↗
PubMed2000

BCR-ABL mediates arsenic trioxide-induced apoptosis independently of its aberrant kinase activity.

In the prechemotherapy era arsenic derivatives were used for treatment of chronic myelogenous leukemia, a myeloproliferative disorder characterized by the t(9;22) translocation, the Philadelphia chromosome (Ph+). In acute promyelocytic leukemia response to arsenic trioxide (As2O3) has been shown to be genetically determined by the acute promyelocytic leukemia-specific t(15;17) translocation product PML/RARalpha. Hence, we reasoned that As2O3 might have a selective inhibitory effect on proliferation of BCR-ABL-expressing cells. Here, we report that: (a) As2O3 induced apoptosis in Ph+ but not in Ph- lymphoblasts; (b) enforced expression of BCR-ABL in U937 cells dramatically increased the sensitivity to As2O3; (c) the effect of As2O3 was independent of BCR-ABL kinase activity; and (d) As2O3 reduced proliferation of chronic myelogenous leukemia blasts but not of peripheral CD34+ progenitors. In summary, these data establish As2O3 as a tumor cell-specific agent, making its clinical application in Ph+ leukemia feasible.

Antigens, CD34↗
PubMed2002

[Role of the three-dimensional distribution of abl and bcr genes in the formation of bcr/abl fusion gene in interphase neucleus].

OBJECTIVE: To explore the mechanism of bcr/abl fusion gene formation in view of its biological stereology. METHODS: Assisted by fluorescent in situ hybridization combined with confocal laser scanning microscopy, we observed the effect of gamma-ray exposure on three-dimensional distribution of bcr and abl genes in the interphase nucleus of IM-9 cell line. RESULTS: In interphase nuclei of IM-9 cells, abl and bcr genes retained their own definite distribution patterns that were dynamically and regularly modulated along with the phases of the cell cycle. gamma-ray exposure, however, produced shortened distances between the 2 genes. CONCLUSION: The accessibility of abl and bcr genes to each other in the interphase nuclei is one of the factors for bcr/acl fusion gene formation.

Cell Cycle↗