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Next-generation sequencing for sensitive detection of BCR-ABL1 mutations relevant to tyrosine kinase inhibitor choice in imatinib-resistant patients.

ABSTRACT: 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.

SUBMITTER: Soverini S

PROVIDER: S-EPMC5008338 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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Next-generation sequencing for sensitive detection of BCR-ABL1 mutations relevant to tyrosine kinase inhibitor choice in imatinib-resistant patients.

Soverini Simona S De Benedittis Caterina C Polakova Katerina Machova KM Linhartova Jana J Castagnetti Fausto F Gugliotta Gabriele G Papayannidis Cristina C Mancini Manuela M Klamova Hana H Salvucci Marzia M Crugnola Monica M Iurlo Alessandra A Albano Francesco F Russo Domenico D Rosti Gianantonio G Cavo Michele M Baccarani Michele M Martinelli Giovanni G

Oncotarget 20160401 16

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 ...[more]

PMID: 26980736

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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.

Project description:BackgroundTreatment-free remission in chronic myeloid leukaemia-ie, achievement of a sustained deep molecular response leading to discontinuation of BCR-ABL1 tyrosine kinase inhibitor (TKI) therapy-has become a potential aim of therapy. Highly priced second-generation TKIs might offer deep molecular response status more quickly and for more patients than imatinib; however, with the availability and lower cost of generic imatinib, the value of second-generation TKIs as frontline therapy for this particular treatment endpoint remains unknown. We aimed to assess the potential value of second-generation TKIs used as frontline therapy in patients with chronic myeloid leukaemia in chronic phase in relation to the probability of achieving sustained deep molecular responses compared with generic imatinib, and the associated cost of each modality.MethodsWe used a decision analytic model to consider the value of different TKI approaches from the payer's perspective. The proportion of patients achieving sustained deep molecular response after 5 years of treatment in chronic phase was estimated at 26% with imatinib and 44% with second-generation TKIs. We also modelled more favourable scenarios of the proportion of patients achieving such response with second-generation TKIs at 66%, 88%, and a near-perfect response of 99%. For each scenario, we examined the impact of the combination of health utilities for chronic-phase chronic myeloid leukaemia (base case 0·89, range 0-1) and the annual cost of second-generation TKIs (base case US$152 814 [ie, the price of nilotinib in the USA], range 0-240 000) on the cost-effectiveness of second-generation TKIs compared with generic imatinib. We used different price scenarios for generic imatinib in the USA (average price $35 000 per year; lowest price $4400 per year), Europe ($4000 per year), and developing countries ($2100 per year). We calculated incremental cost-effectiveness ratios (ICERs) and assessed cost-effectiveness by considering two societal willingness-to-pay thresholds: $50 000 per quality-adjusted life-year (QALY) in all markets and $200 000 per QALY in the USA.FindingsIn the base case, we obtained an ICER of $22 765 208, meaning that second-generation TKIs as frontline therapy to achieve sustained deep molecular response was not cost-effective under either of the societal willingness-to-pay thresholds. In our sensitivity analyses, none of the explored scenarios showed potential treatment value for use of second-generation TKIs at the current prices in the USA or at the price of $30 000-40 000 per year elsewhere. For example, considering a scenario in the USA using second-generation TKIs versus imatinib (annual price $4400 per year) with the potential benefit in favour of second-generation TKI (willingness to pay $200 000 per QALY, 66% of patients achieving sustained deep molecular response, and health utility of the chronic phase of 0·1), the cost of second-generation TKIs would need to be less than $25 000 per year to be a cost-effective option. Under the same conditions in developing nations, with a price of generic imatinib of $2100 per year and a willingness to pay of $50 000 per QALY, the annual price of second-generation TKIs should not exceed $10 000 per year of therapy.InterpretationConsidering the current prices of second-generation TKIs and of generic imatinib under different pricing scenarios in the USA, Europe, and developing countries, second-generation TKIs at current prices do not offer good value as frontline therapy in chronic myeloid leukaemia in order to achieve sustained deep molecular response and treatment-free remission.FundingNational Cancer Institute.

Dataset Information

Next-generation sequencing for sensitive detection of BCR-ABL1 mutations relevant to tyrosine kinase inhibitor choice in imatinib-resistant patients.

Publications

Next-generation sequencing for sensitive detection of BCR-ABL1 mutations relevant to tyrosine kinase inhibitor choice in imatinib-resistant patients.

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