BCR-ABL1 kinase domain mutation analysis by next generation sequencing detected additional mutations in chronic myeloid leukemia patients with suboptimal response to imatinib.
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ABSTRACT:
SUBMITTER: Benjamin ESB
PROVIDER: S-EPMC7611165 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Chronic myeloid leukemia in chronic phase (CML-CP) cells that harbor oncogenic BCR-ABL1 and normal ABL1 allele often become resistant to the ABL1 kinase inhibitor imatinib. Here, we report that loss of the remaining normal ABL1 allele in these tumors, which results from cryptic interstitial deletion in 9q34 in patients who did not achieve a complete cytogenetic remission (CCyR) during treatment, engenders a novel unexpected mechanism of imatinib resistance. BCR-ABL1-positive Abl1(-/-) leukemia cells were refractory to imatinib as indicated by persistent BCR-ABL1-mediated tyrosine phosphorylation, lack of BCR-ABL1 protein degradation, increased cell survival, and clonogenic activity. Expression of ABL1 kinase, but not a kinase-dead mutant, restored the antileukemic effects of imatinib in ABL1-negative chronic myelogenous leukemia (CML) cells and in BCR-ABL1-positive Abl1(-/-) murine leukemia cells. The intracellular concentration of imatinib and expression of its transporters were not affected, although proteins involved in BCR-ABL1 degradation were downregulated in Abl1(-/-) cells. Furthermore, 12 genes associated with imatinib resistance were favorably deregulated in Abl1(-/-) leukemia. Taken together, our results indicate that loss of the normal ABL1 kinase may serve as a key prognostic factor that exerts major impact on CML treatment outcomes.
| S-EPMC3156347 | biostudies-literature
Project description:Accurate quantification of minimal residual disease (MRD) during treatment of chronic myeloid leukemia (CML) guides clinical decisions. The conventional MRD method, RQ-PCR for BCR-ABL1 mRNA, reflects a composite of the number of circulating leukemic cells and the BCR-ABL1 transcripts per cell. BCR-ABL1 genomic DNA only reflects leukemic cell number. We used both methods in parallel to determine the relative contribution of the leukemic cell number to molecular response. BCR-ABL1 DNA PCR and RQ-PCR were monitored up to 24 months in 516 paired samples from 59 newly-diagnosed patients treated with first-line imatinib in the TIDEL-II study. In the first three months of treatment, BCR-ABL1 mRNA values declined more rapidly than DNA. By six months, the two measures aligned closely. The expression of BCR-ABL1 mRNA was normalized to cell number to generate an expression ratio. The expression of e13a2 BCR-ABL1 was lower than that of e14a2 transcripts at multiple time points during treatment. BCR-ABL1 DNA was quantifiable in 48% of samples with undetectable BCR-ABL1 mRNA, resulting in MRD being quantifiable for an additional 5-18 months (median 12 months). These parallel studies show for the first time that the rapid decline in BCR-ABL1 mRNA over the first three months of treatment is due to a reduction in both cell number and transcript level per cell, whereas beyond three months, falling levels of BCR-ABL1 mRNA are proportional to the depletion of leukemic cells.
| S-EPMC6269287 | biostudies-literature
Project description:BCR-ABL1 mutations are a common, well-characterized mechanism of resistance to imatinib as first-line treatment of chronic myeloid leukemia in chronic phase (CML-CP). Less is known about mutation development during first-line treatment with dasatinib and nilotinib, despite increased use because of higher response rates compared with imatinib. Retrospective analyses were conducted to characterize mutation development in patients with newly diagnosed CML-CP treated with dasatinib (n=259) or imatinib (n=260) in DASISION (Dasatinib versus Imatinib Study in Treatment-Naive CML-CP), with 3-year minimum follow-up. Mutation screening, including patients who discontinued treatment and patients who had a clinically relevant on-treatment event (no confirmed complete cytogenetic response (cCCyR) and no major molecular response (MMR) within 12 months; fivefold increase in BCR-ABL1 with loss of MMR; loss of CCyR), yielded a small number of patients with mutations (dasatinib, n=17; imatinib, n=18). Dasatinib patients had a narrower spectrum of mutations (4 vs 12 sites for dasatinib vs imatinib), fewer phosphate-binding loop mutations (1 vs 9 mutations), fewer multiple mutations (1 vs 6 patients) and greater occurrence of T315I (11 vs 0 patients). This trial was registered at www.clinicaltrials.gov as NCT00481247.
| S-EPMC4559757 | biostudies-literature
Project description:Small-molecule-induced degradation of mutant Bcr-Abl1 provides a potential approach to overcome Bcr-Abl1 tyrosine kinase inhibitor (TKI)-resistant chronic myeloid leukemia (CML). Our previous study reported that a synthetic steroidal glycoside SBF-1 showed remarkable anti-CML activity by inducing the degradation of native Bcr-Abl1 protein. Here, we observed the comparable growth inhibition for SBF-1 in CML cells harboring T315I mutant Bcr-Abl1 in vitro and in vivo. SBF-1 triggered its degradation through disrupting the interaction between protein-tyrosine phosphatase 1B (PTP1B) and Bcr-Abl1. Using SBF-1 as a tool, we found that Tyr46 in the PTP1B catalytic domain and Tyr852 in the Bcr-Abl1 pleckstrin-homology (PH) domain are critical for their interaction. Moreover, the phosphorylation of Tyr1086 within the Bcr-Abl1 SH2 domain recruited the E3 ubiquitin ligase c-Cbl to catalyze K27-linked ubiquitin chains, which serve as a recognition signal for p62-dependent autophagic degradation. PTP1B dephosphorylated Bcr-Abl1 at Tyr1086 and prevented the recruitment of c-Cbl, leading to the stability of Bcr-Abl1. This study unravels the action mechanism of PTP1B in stabilizing Bcr-Abl1 protein and indicates that the PTP1B-Bcr-Abl1 interaction might be one of druggable targets for TKI-resistant CML with point mutations.
| S-EPMC9807508 | biostudies-literature
Project description:In chronic myeloid leukemia (CML) and Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) patients who fail imatinib treatment, BCR-ABL1 mutation profiling by Sanger sequencing (SS) is recommended before changing therapy since detection of specific mutations influences second-generation tyrosine kinase inhibitor (2GTKI) choice. We aimed to assess i) in how many patients who relapse on second-line 2GTKI therapy next generation sequencing (NGS) may track resistant mutations back to the sample collected at the time of imatinib resistance, before 2GTKI start (switchover sample) and ii) whether low level mutations identified by NGS always undergo clonal expansion. To this purpose, we used NGS to retrospectively analyze 60 imatinib-resistant patients (CML, n = 45; Ph+ ALL,n = 15) who had failed second-line 2GTKI therapy and had acquired BCR-ABL1 mutations (Group 1) and 25 imatinib-resistant patients (CML, n = 21; Ph+ ALL, n = 4) who had responded to second-line 2GTKI therapy, for comparison (Group 2). NGS uncovered that in 26 (43%) patients in Group 1, the 2GTKI-resistant mutations that triggered relapse were already detectable at low levels in the switchover sample (median mutation burden, 5%; range 1.1%-18.4%). Importantly, none of the low level mutations detected by NGS in switchover samples failed to expand whenever the patient received the 2GTKI to whom they were insensitive. In contrast, no low level mutation that was resistant to the 2GTKI the patients subsequently received was detected in the switchover samples from Group 2. NGS at the time of imatinib failure reliably identifies clinically relevant mutations, thus enabling a more effective therapeutic tailoring.
| S-EPMC5008338 | biostudies-literature
Project description:BackgroundThe BCR-ABL1 translocation occurs in chronic myeloid leukemia (CML) and in 25% of cases with acute lymphoblastic leukemia (ALL). The advent of tyrosine kinase inhibitors (TKI) has fundamentally changed the treatment of CML. However, TKI are not equally effective for treating ALL. Furthermore, de novo or secondary TKI-resistance is a significant problem in CML. We screened a panel of BCR-ABL1 positive ALL and CML cell lines to find models for imatinib-resistance.ResultsFive of 19 BCR-ABL1 positive cell lines were resistant to imatinib-induced apoptosis (KCL-22, MHH-TALL1, NALM-1, SD-1, SUP-B15). None of the resistant cell lines carried mutations in the kinase domain of BCR-ABL1 and all showed resistance to second generation TKI, nilotinib or dasatinib. STAT5, ERK1/2 and the ribosomal S6 protein (RPS6) are BCR-ABL1 downstream effectors, and all three proteins are dephosphorylated by imatinib in sensitive cell lines. TKI-resistant phosphorylation of RPS6, but responsiveness as regards JAK/STAT5 and ERK1/2 signalling were characteristic for resistant cell lines. PI3K pathway inhibitors effected dephosphorylation of RPS6 in imatinib-resistant cell lines suggesting that an oncogene other than BCR-ABL1 might be responsible for activation of the PI3K/AKT1/mTOR pathway, which would explain the TKI resistance of these cells. We show that the TKI-resistant cell line KCL-22 carries a PI3K? E545G mutation, a site critical for the constitutive activation of the PI3K/AKT1 pathway. Apoptosis in TKI-resistant cells could be induced by inhibition of AKT1, but not of mTOR.ConclusionWe introduce five Philadelphia-chromosome positive cell lines as TKI-resistance models. None of these cell lines carries mutations in the kinase domain of BCR-ABL1 or other molecular aberrations previously indicted in the context of imatinib-resistance. These cell lines are unique as they dephosphorylate ERK1/2 and STAT5 after treatment with imatinib, while PI3K/AKT1/mTOR activity remains unaffected. Inhibition of AKT1 leads to apoptosis in the imatinib-resistant cell lines. In conclusion, Ph+ cell lines show a form of imatinib-resistance attributable to constitutive activation of the PI3K/AKT1 pathway. Mutations in PIK3CA, as observed in cell line KCL-22, or PI3K activating oncogenes may undelie TKI-resistance in these cell lines.
| S-EPMC3041785 | biostudies-literature
Project description:Telomeres are specialized nucleoprotein complexes, localized at the physical ends of chromosomes, that contribute to the maintenance of genome stability. One of the features of chronic myeloid leukemia (CML) cells is a reduction in telomere length which may result in increased genomic instability and progression of the disease. Aberrant telomere maintenance in CML is not fully understood and other mechanisms such as the alternative lengthening of telomeres (ALT) are involved. In this work, we employed five BCR-ABL1-positive cell lines, namely K562, KU-812, LAMA-84, MEG-A2, and MOLM-1, commonly used in the laboratories to study the link between mutation, copy number, and expression of telomere maintenance genes with the expression, copy number, and activity of BCR-ABL1. Our results demonstrated that the copy number and expression of BCR-ABL1 are crucial for telomere lengthening. We observed a correlation between BCR-ABL1 expression and telomere length as well as shelterins upregulation. Next-generation sequencing revealed pathogenic variants and copy number alterations in major tumor suppressors, such as TP53 and CDKN2A, but not in telomere-associated genes. Taken together, we showed that BCR-ABL1 kinase expression and activity play a crucial role in the maintenance of telomeres in CML cell lines. Our results may help to validate and properly interpret results obtained by many laboratories employing these in vitro models of CML.
| S-EPMC7601685 | biostudies-literature
Project description:In chronic myeloid leukemia, the identification of individual BCR-ABL1 fusions is required for the development of personalized medicine approach for minimal residual disease monitoring at the DNA level. Next generation sequencing (NGS) of amplicons larger than 1000 bp simplified and accelerated a process of characterization of patient-specific BCR-ABL1 genomic fusions. NGS of large regions upstream and downstream the individual breakpoints in BCR and ABL1 genes, respectively, also provided information about the sequence variants such are single nucleotide polymorphisms.
| S-EPMC4409993 | biostudies-literature
Project description:The management of chronic myeloid leukemia with BCR-ABL1 tyrosine kinase inhibitors has evolved chronic myeloid leukemia into a chronic, manageable disease. A patient-centered approach is important for the appropriate management of chronic myeloid leukemia and optimization of long-term treatment outcomes. The pharmacist plays a key role in treatment selection, monitoring drug-drug interactions, identification and management of adverse events, and educating patients on adherence. The combination of tyrosine kinase inhibitors with unique safety profiles and individual patients with unique medical histories can make managing treatment difficult. This review will provide up-to-date information regarding tyrosine kinase inhibitor-based treatment of patients with chronic myeloid leukemia. Management strategies for adverse events and considerations for drug-drug interactions will not only vary among patients but also across tyrosine kinase inhibitors. Drug-drug interactions can be mild to severe. In instances where co-administration of concomitant medications cannot be avoided, it is critical to understand how drug levels are impacted and how subsequent dose modifications ensure therapeutic drug levels are maintained. An important component of patient-centered management of chronic myeloid leukemia also includes educating patients on the significance of early and regular monitoring of therapeutic milestones, emphasizing the importance of adhering to treatment in achieving these targets, and appropriately modifying treatment if these clinical goals are not being met. Overall, staying apprised of current research, utilizing the close pharmacist-patient relationship, and having regular interactions with patients, will help achieve successful long-term treatment of chronic myeloid leukemia in the age of BCR-ABL1 tyrosine kinase inhibitors.
| S-EPMC6094551 | biostudies-literature
Project description:The most frequent BCR-ABL1-p210 transcripts in chronic myeloid leukemia (CML) are e14a2 and e13a2. Imatinib (IM) is the most common first-line tyrosine-kinase inhibitor (TKI) used to treat CML. Some studies suggest that BCR-ABL1 transcript types confer different responses to IM. The objective of this study was to correlate the expression of e14a2 or e13a2 to clinical characteristics, cumulative cytogenetic and molecular responses to IM, acquisition of deep molecular response (DMR) and its duration (sDMR), progression rate (CIP), overall survival (OS), and treatment-free remission (TFR) rate. We studied 202 CML patients, 76 expressing the e13a2 and 126 the e14a2, and correlated the differential transcript expression with the above-mentioned parameters. There were no differences in the cumulative incidence of cytogenetic responses nor in the acquisition of DMR and sDMR between the two groups, but the e14a2 transcript had a positive impact on molecular response during the first 6 months, whereas the e13a2 was associated with improved long-term OS. No correlation was observed between the transcript type and TFR rate.
| S-EPMC8307111 | biostudies-literature