Imatinib Intolerance Is Associated With Blastic Phase Development in Philadelphia Chromosome-Positive Chronic Myeloid Leukemia

Computational Identification of BCR-ABL Oncogenic Signaling as a Candidate Target of Withaferin A and Withanone

Withaferin-A (Wi-A), a secondary metabolite extracted from Ashwagandha (Withania somnifera), has been shown to possess anticancer activity. However, the molecular mechanism of its action and the signaling pathways have not yet been fully explored. We performed an inverse virtual screening to investigate its binding potential to the catalytic site of protein kinases and identified ABL as a strong candidate. Molecular docking and molecular dynamics simulations were undertaken to investigate the effects on BCR-ABL oncogenic signaling that is constitutively activated yielding uncontrolled proliferation and inhibition of apoptosis in Chronic Myeloid Leukemia (CML). We found that Wi-A and its closely related withanolide, Withanone (Wi-N), interact at both catalytic and allosteric sites of the ABL. The calculated binding energies were higher in the case of Wi-A at catalytic site (−82.19 ± 5.48) and allosteric site (−67.00 ± 4.96) as compared to the clinically used drugs Imatinib (−78.11 ± 5.21) and Asciminib (−54.00 ± 6.45) respectively. Wi-N had a lesser binding energy (−42.11 ± 10.57) compared to Asciminib at the allosteric site. The interaction and conformational changes, subjected to ligand interaction, were found to be similar to the drugs Imatinib and Asciminib. The data suggested that Ashwagandha extracts containing withanolides, Wi-A and Wi-N may serve as natural drugs for the treatment of CML. Inhibition of ABL is suggested as one of the contributing factors of anti-cancer activity of Wi-A and Wi-N, warranting further in vitro and in vivo experiments.

Bcr-Abl Tyrosine Kinase Inhibitors in the Treatment of Pediatric CML

The therapeutic approach to Chronic Myeloid Leukemia (CML) has changed since the advent of the tyrosine kinase inhibitor (TKI) imatinib, which was then followed by the second generation TKIs dasatinib, nilotinib, and, finally, by ponatinib, a third-generation drug. At present, these therapeutic options represent the first-line treatment for adults. Based on clinical experience, imatinb, dasatinib, and nilotinib have been approved for children even though the studies that were concerned with efficacy and safety toward pediatric patients are still awaiting more specific and high-quality data. In this scenario, it is of utmost importance to prospectively validate data extrapolated from adult studies to set a standard therapeutic management for pediatric CML by employing appropriate formulations on the basis of pediatric clinical trials, which allow a careful monitoring of TKI-induced adverse effects especially in growing children exposed to long-term therapy.

Cross-talk between Bcr-abl and the Thioredoxin System in Chronic Myeloid Leukaemia: Implications for CML Treatment

Chronic myeloid leukaemia (CML) is currently treated with inhibitors of the CML specific oncoprotein, bcr-abl. While this strategy is initially successful, drug resistance can become a problem. Therefore, new targets need to be identified to ensure the disease can be appropriately managed. The thioredoxin (Trx) system, comprised of Trx, thioredoxin reductase (TrxR), and NADPH, is an antioxidant system previously identified as a target for therapies aimed at overcoming drug resistance in other cancers. We assessed the effectiveness of TrxR inhibitors on drug resistant CML cells and examined links between TrxR and the bcr-abl cell-signalling pathway. Two TrxR inhibitors, auranofin and [Au(d2pype)2]Cl, increased intracellular ROS levels and elicited apoptosis in both sensitive and imatinib resistant CML cells. Inhibition of TrxR activity by these pharmacological inhibitors, or by specific siRNA, also resulted in decreased bcr-abl mRNA and protein levels, and lower bcr-abl downstream signalling activity, potentially enhancing the effectiveness of TrxR inhibitors as CML therapies. In addition, imatinib resistant CML cell lines showed upregulated expression of the Trx system. Furthermore, analysis of datasets showed that CML patients who did not respond to imatinib had higher Trx mRNA levels than patients who responded to treatment. Our study demonstrates a link between the Trx system and the bcr-abl protein and highlights the therapeutic potential of targeting the Trx system to improve CML patients' outcomes.

[Analysis of the efficacy and influencing factors of nilotinib or dasatinib as second- or third-line treatment in patients with chronic myeloid leukemia in the chronic phase and accelerated phase]

Objective: To explore the efficacy and prognosis of nilotinib or dasatinib as second- or third-line treatment in patients with chronic myeloid leukemia (CML) in the chronic phase (CP) and accelerated phase (AP) . Methods: From January 2008 to November 2018, the data of CML patients who failed first- or second-line tyrosine kinase inhibitor (TKI) -therapy received nilotinib or dasatinib as second-line and third-line therapy were retrospectively reviewed. Results: A total of 226 patients receiving nilotinib or dastinib as second-line (n=183) and third-line (n=43) therapy were included in this study. With a median follow-up of 21 (range, 1-135) months, the cumulative rates of complete hematological response (CHR) , complete cytogenetic response (CCyR) and major molecular response (MMR) were 80.4%, 56.3%and 38.3%, respectively in those receiving TKI as second-line TKI therapy. The 3-year progression-free survival (PFS) and overall survival (OS) rates were 78.7%and 93.1%, respectively. Multivariate analyses showed that Sokal high risk, female gender, the best response achieved Collapse

Key Words

• Dasatinib
• Imatinib
• Leukemia, myeloid, chronic, BCR-ABL positive
• Nilotinib

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MESH Headings

• Dasatinib/therapeutic use
• Female
• Humans
• Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
• Pyrimidines/therapeutic use
• Retrospective Studies
• Treatment Outcome

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Grants

• 81770161 National Natural Science Foundation of China

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Affiliation(s)

T Yuan Peking University People's Hospital, Peking University Institute of Hematology, Beijing 100044, China
Y Y Lai
Y Z Qin
H X Shi
X J Huang
Y Hou
Q Jiang

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[Analysis on tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia in the real world: experience from single center]

Objective: To explore status of tyrosine kinase inhibitor (TKI) discontinuation in patients with chronic myeloid leukemia (CML) in the chronic phase (CP) in the real world, to analyze causes, factors and outcomes associated with TKI discontinuation and the possibility of pursuit treatment-free remission (TFR) in China. Methods: From January 2013 to August 2016, data of CML-CP patients in Peking University People's Hospital which were not enrolled in clinical trials were retrospectively collected and analyzed. Results: Data of 662 CML-CP patients were collected. With a median follow-up after TKI-therapy of 26 months (range, 3-187 months) , 187 patients (28.2%) experienced TKI cessation of at least 2 weeks. Causes of TKI discontinuation included hematologic adverse events 57.8% (n=108) , non-hematologic adverse events 30.4% (n=57) , financial burden 25.1% (n=47) , and others 7.0% (n= 13) . Multivariate analyses showed female, ≥40 years, no co-morbidity, and interval from diagnosis to TKI initiation ≥6 months, TKI switch and patients from other hospitals were factors associated with TKI discontinuation because of hematologic adverse effects. Female and patients from other hospitals were factors associated with TKI discontinuation because of non-hematologic adverse effect. TKI switch, generic TKI used and patients from other hospitals were factors associated with TKI discontinuation because of financial toxicity. Patients TKI discontinuation because of hematologic, non-hematologic or financial toxicity achieved a lower complete cytogenetic response or complete molecular response (CMR) than those with uninterrupted TKI-therapy. Patients with TKI discontinuation because of hematologic or financial toxicity had a shorter progression-free survival than those with uninterrupted TKI-therapy. 5 of 7 patients who obtained sustained CMR and discontinued TKI-therapy experienced disease recurrence with a median duration of 3 months (range, 2-32 months) . In 39 patients from other hospitals who aimed to confirm their optimal response of sustained CMR in Peking University People's Hospital, 21 (53.8%) were BCR-ABL positive. Conclusion: In the real world in China, half of CML-CP patients who discontinued TKI-therapy were incurred to TKI-related hematologic adverse effect, and both a quarter of them, TKI-related non-hematologic toxicities and financial toxicity, respectively. Discontinued TKI-therapy due to hematologic adverse events or financial toxicity was associated with lower TKI-therapy response rates. Nowadays, based on the Chinese situation, it is too early to talk about TFR.