Efficacy of escalated imatinib combined with cytarabine in newly diagnosed patients with chronic myeloid leukemia

Outcome prediction of chronic myeloid leukemia (CML) in children

We evaluated the feasibility of existing risk assessment tools for chronic myeloid leukemia (CML) in children. Fifty-five patients with newly diagnosed CML between 1996 and 2019 were included. Forty-nine patients presented in chronic phase, thirty-six of whom were treated with upfront tyrosine kinase inhibitor (CP-TKI group); one presented in accelerated phase and four in blastic phase. Treatment, survival, responses, and tolerance were evaluated. All patients in the CP-TKI group received imatinib as their first TKI treatment. The 10-year overall survival (OS), progression-free survival (PFS), and event-free survival (EFS) of TKI-treated group was 97%, 91.4%, and 72.3%, respectively. At 60 months, the rates of major molecular response were 81.2% and deep molecular response was 67.5%. The EUTOS long-term survival (ELTS) risk grouping did not predict OS, PFS, or EFS. The IMAFAIL risk groups were correlated with the risk of imatinib failure. Further studies are required to modify the existing risk assessment tools for children.

New Approaches and Treatment Combinations for the Management of Chronic Myeloid Leukemia

Current treatment of chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKI) is effective in many patients, but is not curative and frequently limited by intolerance or resistance. Also, treatment free remission is a novel option for CML patients and requires reaching a deep molecular remission, which is not consistently achieved with TKI monotherapy. Together, multiple unmet clinical needs remain and therefore the continued need to explore novel treatment strategies. With increasing understanding of CML biology, many options have been explored and are under investigation. This includes the use asciminib as first in class inhibitor targeting the myristoyl pocket of BCR-ABL, combination treatments with established non-TKI drugs such as interferon and drugs with novel targets relevant to CML biology such as gliptins and thiazolidinediones. Together, an overview is provided of treatment strategies in development for CML beyond current TKI monotherapy.

Efficacy and Safety of Imatinib in Paediatric CML - A Single Centre Study

BACKGROUND/AIM

Chronic myeloid leukaemia (CML) rarely affects the paediatric population and has an incidence of 0.06-0.12/100,000 children per year. The dire clinical course of paediatric CML is further exacerbated by the adverse effects of long-term imatinib therapy.

PATIENTS AND METHODS

Our cohort comprised 14 CML patients who were treated with imatinib between July 2010 and September 2018. The European Leukaemia Net (ELN) standard milestones of response criteria were used to evaluate its therapeutic effectiveness.

RESULTS

Complete haematological remission and partial cytogenetic response were achieved in all patients. Complete cytogenetic response was achieved in seven patients. Major molecular response was achieved in six patients. Two patients underwent haematopoietic stem cell transplantation due to unsatisfactory response to imatinib.

CONCLUSION

Imatinib is effective in treating paediatric CML and limits the progression to advanced stages, however, the quality of life still needs to be optimised.

Selecting the best frontline treatment in chronic myeloid leukemia

With the discovery of Philadelphia chromosome, understanding of chronic myeloid leukemia (CML) pathobiology has tremendously increased. Development of tyrosine kinase inhibitors (TKI) targeting the BCR/ABL1 oncoprotein has changed the landscape of the disease. Today, the expected survival of CML patients, if properly managed, is likely to be similar to the general population. Imatinib is the first-approved TKI in CML treatment, and for several years, it was the only option in the frontline setting. Four years ago, second-generation TKIs (nilotinib and dasatinib) were approved as alternative frontline options. Now, clinicians are faced the challenge of making decision for which TKI to chose upfront. Second-generation TKIs have been demonstrated to induce deeper and faster responses compared to imatinib; however, none of three TKIs have been shown to have a clear survival advantage, they all are reasonable options. In contrast, when considering therapy in individual patients, the case may be stronger for a specific TKI. Co-morbidities of the patient and side effect profile of the TKI of interest should be an important consideration in decision making. At present, the cost nilotinib or dasatinib is not remarkably different from imatinib. However, patent for imatinib is expected to expire soon, and it will be available as a generic. Clinicians, then, need to weigh the advantages some patients gain with nilotinib or dasatinib in the frontline setting against the difference in cost. Whatever TKI is chosen as frontline, intolerance, non-compliance, or treatment failure should be recognized early as a prompt intervention increases the chance of achieving best possible response.

MiR-362-5p promotes the malignancy of chronic myelocytic leukaemia via down-regulation of GADD45α

Background

MicroRNAs (miR, miRNAs) play pivotal roles in numerous physiological and pathophysiological contexts. We investigated whether miR-362-5p act as an oncogene in chronic myeloid leukaemia (CML) and aimed to understand its potential underlying mechanisms.

Methods

We compared the miR-362-5p expression levels between CML and non-CML cell lines, and between fresh blood samples from CML patients and normal healthy controls using quantitative real-time PCR (qPCR). Cell counting kit-8 (CCK-8) and Annexin V-FITC/PI analyses were used to measure the effects of miR-362-5p on proliferation and apoptosis, and Transwell assays were used to evaluate migration and invasion. A xenograft model was used to examine in vivo tumourigenicity. The potential target of miR-362-5p was confirmed by a luciferase reporter assay, qPCR and western blotting. Involvement of the JNK_1/2 and P38 pathways was investigated by western blotting.

Results

miR-362-5p was up-regulated in CML cell lines and fresh blood samples from CML patients, and was associated with Growth arrest and DNA damage-inducible (GADD)45α down-regulation. Inhibition of miR-362-5p simultaneously repressed tumour growth and up-regulated GADD45α expression in a xenograft model. Consistently, the knockdown of GADD45α expression partially neutralized the effects of miR-362-5p inhibition. Furthermore study suggested that GADD45α mediated downstream the effects of miR-362-5p, which might indirectly regulates the activation of the JNK_1/2 and P38 signalling pathways.

Conclusion

miR-362-5p acts as an oncomiR that down-regulates GADD45α, which consequently activates the JNK_1/2 and P38 signalling. This finding provides novel insights into CML leukaemogenesis and may help identify new diagnostic and therapeutic targets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0465-3) contains supplementary material, which is available to authorized users.

Tyrosine Kinase Inhibitors Early in the Disease Course: Lessons From Chronic Myelogenous Leukemia

The landscape of chronic myeloid leukemia (CML) management has changed with the advent of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 oncoprotein. Imatinib mesylate, followed by nilotinib and dasatinib, has been approved for newly diagnosed patients. Since none of these TKIs show survival superiority, the drug choice is a challenge. Even so, the rate of deeper and earlier responses is higher with second-generation TKIs than it is with imatinib, and, in general, better response is associated with a survival advantage, regardless of TKI type being used. Patients should be monitored carefully for response, and treatment failure should prompt a timely switch to another TKI. Side effect profile and drug cost are other important considerations in therapy choice. In several clinical studies, achieving undetectable and durable disease status allowed some patients to discontinue the TKI and enjoy long-term treatment-free remission. Cure for CML may be possible with TKIs alone or TKIs in combination with other investigational therapies. However, due to lack of long-term outcome data and absence of consensus for the definition of optimal response and time to stop TKIs, discontinuation is discouraged outside of a clinical trial.

Is Imatinib Maintenance Required for Patients with Relapse Chronic Myeloid Leukemia Post-Transplantation Obtaining CMR? A Pilot Retrospective Investigation

Imatinib can induce complete molecular remission (CMR) in relapse chronic myelogenous leukemia (CML) after allogeneic hematopoietic stem cell transplantation, but it is indefinite whether imatinib is required to maintain CMR. We retrospectively reviewed 37 relapse CML post-transplants treated with imatinib (n = 20) or donor lymphocyte infusion (DLI) (n = 17). The rate of CMR was 85% and 76.47% (P = 0.509) and treatment-related mortality was 0% and 29.4% (P = 0.019), respectively, in imatinib and DLI groups. Fifteen patients obtaining CMR voluntarily ceased imatinib, and did not experience relapse. The 8-year overall survival (OS) after relapse was 85%±8% and 40.3±12.1% (P = 0.017), and disease-free survival (DFS) after relapse was 85%±8% and 40.3±12.1% (P = 0.011), respectively, in imatinib and DLI groups. Imatinib resulted in higher OS and DFS than that of DLI in relapse CML. Imatinib maintenance might not be required for patients with relapse CML post-transplants after they achieved full donor chimerism and CMR.

High-dose imatinib versus high-dose imatinib in combination with intermediate-dose cytarabine in patients with first chronic phase myeloid leukemia: a randomized phase III trial of the Dutch-Belgian HOVON study group

Despite the revolutionary change in the prognosis of chronic myeloid leukemia (CML) patients with the introduction of imatinib, patients with resistant disease still pose a considerable problem. In this multicenter, randomized phase III trial, we investigate whether the combination of high-dose imatinib and intermediate-dose cytarabine compared to high-dose imatinib alone, improves the rate of major molecular response (MMR) in newly diagnosed CML patients. This study was closed prematurely because of declining inclusion due to the introduction of second generation tyrosine kinase inhibitors and only one third of the initially required patients were accrued. One hundred nine patients aged 18-65 years were randomly assigned to either imatinib 800 mg (n = 55) or to imatinib 800 mg in combination with two successive cycles of cytarabine 200 mg/m(2) for 7 days (n = 54). After a median follow-up of 41 months, 67 % of patients were still on protocol treatment. The MMR rate at 12 months was 56 % in the imatinib arm and 48 % in the combination arm (p = 0.39). Progression-free survival was 96 % after 1 year and 89 % after 4 years. Four-year overall survival was 97 %. Adverse events grades 3 and 4 were more common in the combination arm. The addition of intermediate-dose of cytarabine to imatinib did not improve the MMR rate at 12 months. However, the underpowering of the study precludes any definitive conclusions. This trial is registered at www.trialregister.nl (NTR674).

DNA damage response in imatinib resistant chronic myeloid leukemia K562 cells

Resistance to imatinib in patients with chronic myeloid leukemia can lead to advanced disease and blast crisis. Conventional chemotherapy with DNA damaging agents is then used, alone or in combination with other tyrosine kinase inhibitors (TKIs). Our aim was to assess whether imatinib resistant K562 cells were also resistant to DNA damaging agents. After treatment with H(2)O(2) and doxorubicin, but not camptothecin, cell survival was higher in imatinib resistant cells compared to parental cells. DNA damage, measured by comet and γ-H2AX assays, was lower in imatinib resistant cells. mRNA expression levels of 50 genes of the DNA damage response pathway showed increased expression of the base excision repair (BER) genes MBD4 and NTHL1. Knockdown of MBD4 and NTHL1 expression in resistant cells using siRNA decreased cell survival after treatment with H(2)O(2) and doxorubicin. Our results indicate that imatinib resistant cells display cross-resistance to oxidative agents, partly through up-regulation of BER genes. Expression of these genes in imatinib resistant patients was not significantly different compared to sensitive patients. However, the strategy followed in this study could help identify chemotherapeutic agents that are more effective as alternative agents in cases of resistance to TKIs.

The expanding options for front-line treatment in patients with newly diagnosed CML

The past decade has seen remarkable advances in the treatment of chronic myeloid leukemia (CML). The discovery of the underlying cause of CML, a chromosomal translocation resulting in the expression of an aberrant tyrosine kinase, has enabled the rational development of targeted therapy with tyrosine kinase inhibitors (TKIs). The first available TKI, imatinib, dramatically improved survival rates and demonstrated the potential for long-term treatment. A number of additional strategies have been tested to further maximize outcomes in patients with newly diagnosed CML, including newer TKIs, imatinib dose escalation, and combination therapy. The advanced, more potent TKIs, nilotinib and dasatinib, have proven effective for newly diagnosed patients and for those who experience inadequate response or intolerance to imatinib. Randomized phase 3 studies have shown that nilotinib and dasatinib are more efficacious than imatinib in achieving primary study endpoints. Nilotinib was superior to imatinib in the rate of major molecular response at 12 months; dasatinib was superior to imatinib in the rate of complete cytogenetic response by 12 months. These phase 3 studies are ongoing to further define longer-term efficacy and safety. Research on additional contributing signaling pathways in CML, T315I mutations, and other causes of treatment resistance has identified additional potential treatments that are now in early stages of clinical development, with encouraging preliminary results. With continued advances, it is conceivable that the ultimate goal - a cure for CML - is in our sights.

Residual normal stem cells can be detected in newly diagnosed chronic myeloid leukemia patients by a new flow cytometric approach and predict for optimal response to imatinib

Insensitivity of chronic myeloid leukemia (CML) hematopoietic stem cells to tyrosine kinase inhibitors (TKIs) prevents eradication of the disease and may be involved in clinical resistance. For improved treatment results more knowledge about CML stem cells is needed. We here present a new flow cytometric approach enabling prospective discrimination of CML stem cells from their normal counterparts within single-patient samples. In 24 of 40 newly diagnosed CML patients residual normal CD34(+)CD38(-) stem cells could be identified by lower CD34 and CD45 expression, lower forward/sideward light scatter and by differences of lineage marker expression (CD7, CD11b and CD56) and of CD90. fluorescent in situ hybridization (FISH) analysis on Fluorescence-activated cell sorting sorted cells proved that populations were BCR-ABL positive or negative and long-term liquid culture assays with subsequent colony forming unit assays and FISH analysis proved their stem cell character. Patients with residual non-leukemic stem cells had lower clinical risk scores (Sokal, Euro), lower hematological toxicity of imatinib (IM) and better molecular responses to IM than patients without. This new approach will expand our possibilities to separate CML and normal stem cells, present in a single bone marrow or peripheral blood sample, thereby offering opportunities to better identify new CML stem-cell-specific targets. Moreover, it may guide optimal clinical CML management.

Tyrosine kinase inhibitors as modulators of ATP binding cassette multidrug transporters: substrates, chemosensitizers or inducers of acquired multidrug resistance?

INTRODUCTION

Anticancer tyrosine kinase inhibitors (TKIs) are small molecule hydrophobic compounds designed to arrest aberrant signaling pathways in malignant cells. Multidrug resistance (MDR) ATP binding cassette (ABC) transporters have recently been recognized as important determinants of the general ADME-Tox (absorption, distribution, metabolism, excretion, toxicity) properties of small molecule TKIs, as well as key factors of resistance against targeted anticancer therapeutics.

AREAS COVERED

The article summarizes MDR-related ABC transporter interactions with imatinib, nilotinib, dasatinib, gefitinib, erlotinib, lapatinib, sunitinib and sorafenib, including in vitro and in vivo observations. An array of methods developed to study such interactions is presented. Transporter-TKI interactions relevant to the ADME-Tox properties of TKI drugs, primary or acquired cancer TKI resistance, and drug-drug interactions are also reviewed.

EXPERT OPINION

Based on the concept presented in this review, TKI anticancer drugs are considered as compounds recognized by the cellular mechanisms handling xenobiotics. Accordingly, novel anticancer therapies should equally focus on the effectiveness of target inhibition and exploration of potential interactions of the designed molecules by membrane transporters. Thus, targeted hydrophobic small molecule compounds should also be screened to evade xenobiotic-sensing cellular mechanisms.

Challenges for allogeneic hematopoietic stem cell transplantation in chronic myeloid leukemia in the era of tyrosine kinase inhibitors

Following the introduction of the tyrosine kinase inhibitor (TKI) imatinib in the treatment of chronic myeloid leukemia (CML) patients, the allogeneic hematopoietic stem cell transplantation (HSCT) scene in CML has changed dramatically. The number of patients receiving HSCT in first chronic phase (CP) has declined rapidly, as allogeneic HSCT in CP is now performed in these patients only in case of failure or intolerance of TKIs. Second, those CML patients who undergo allogeneic HSCT represent a selection of high-risk patients due to more advanced disease with high rates of accelerated or blast phase (being associated with an increased relapse risk), advanced age and relevant co-morbidities. Efforts at meeting these special challenges are being developed: treatment with TKIs aims to improve the pre-transplant remission status before HSCT. Dose-reduced conditioning protocols were introduced to decrease transplant-related mortality in patients with co-morbidities or older age. In the post-transplant period, TKIs may be administered for prophylaxis and for treatment of post-transplant relapse. Still, the outcome of patients in advanced CML phases remains guarded, and requires an improvement in current transplant strategies.