Identification by molecular dynamic simulation and in vitro validation of SISB-A1, N-[1-(4-bromophenyl)-3-methyl-1H-pyrazol-5-yl]-2-[(2-oxo-4-phenyl-2H-chromen-7-yl) oxy], as an inhibitor of the AblT315I mutant kinase to combat imatinib resistance in chronic myeloid leukemia

The discovery of imatinib, a specific inhibitor of Abl kinase, revolutionized the therapeutic approach to chronic myeloid leukemia (CML); however, its efficacy can be impeded by the emergence of novel mutations within the kinase domain, particularly AblT315I, that lead to the development of drug resistance. It therefore remains necessary to identify specific inhibitors that can effectively target imatinib-resistant CML harboring the AblT315I mutation. A natural product library sourced from the ZINC database was screened against the experimental structure of AblT315I kinase to identify compounds that selectively target the mutated kinase. The top-scoring compound was empirically tested for inhibition of AblT315I kinase using a luminescence-based kit and for impact on cellular proliferation using the BaF3-BCR-ABL-T315I stable cell line. Computational docking and molecular dynamic simulations identified the compound SISB-A1, N-[1-(4-bromophenyl)-3-methyl-1H-pyrazol-5-yl]-2-[(2-oxo-4-phenyl-2H-chromen-7-yl)oxy] acetamide, to effectively bind the catalytic domain of the mutant AblT315I kinase. Moreover, SISB-A1 exhibited greater preference than imatinib for amino acid residues of the mutant kinase's active site, including isoleucine 315. MMPBSA-based Gibbs binding free energy estimation predicted SISB-A1 to have a free energy of -51.5 versus -65.0 kcal/mol for the conventional AblT315I inhibitor ponatinib. Cell proliferation assays showed SISB-A1 to have a GI50 of 164.0 nM against the ABL-T315I stable cell line, whereas imatinib had a GI50 of 5035 nM. The IC50 value obtained for SISB-A1 against the AblT315I kinase was 197.9 nM. The results indicate SISB-A1 to have a notable ability to bind the catalytic domain of the AblT315I mutant kinase and effectively suppress its activity, thereby surpassing the associated resistance to imatinib. Continued advancement of this lead compound has the potential to yield innovative therapeutics for imatinib-resistant CML.

Chronic Myeloid Leukemia in Children and Adolescents

Acute leukemia is the most common malignancy in childhood, while chronic myeloid leukemia is rare, accounting for only 2% to 3% of all leukemia in childhood and 9% in adolescents, with an annual incidence of 1 and 2.2 cases per million in the two groups. The goal in Pediatrics is remission and cure with tyrosine kinase inhibitors (TKIs) and monitoring closely for long-term effects of TKI use.

Frailty in chronic myeloid leukemia: evidence from 2016-2018 Nationwide Inpatient Sample of the US

BACKGROUND

Frailty is a marker of poor prognosis in older adults with hematologic malignancies and contributes to the severe vulnerability of the aging population to adverse health outcomes. This study aimed to determine the association between frailty and outcomes in hospitalized patients with chronic myeloid leukemia (CML).

METHODS

The International Classification of Diseases (ICD-10) identified data on hospitalized patients 20 years or older admitted with CML between 2016 and 2018 in the US National Inpatient Sample (NIS) database. The cohort was further divided into groups of patients with or without frailty. Logistic regression analysis was performed to determine associations between study variables and clinical outcomes. A stratified analysis of the association between frailty and in-hospital mortality by age group was also performed.

RESULTS

A total of 13,849 hospitalized patients with CML were included, 49.6% of whom had frailty. The mean age of the patients was 65.1 years, and 7,619 (56.2%) of them were male. Frailty was associated with nearly 4 times the risk of in-hospital mortality, 3 times the risk of unfavorable discharge, 3 times the risk of prolonged LOS,, and significantly more in total hospital costs. In addition, frailty was associated with a significantly increased risk of in-hospital mortality in all age subgroups (< 40 years, 40-59 years, and > 60 years) compared with no frailty.

CONCLUSIONS

Frailty strongly predicts poor clinical outcomes in US patients with CML.

Estimating prognostic relevant cutoff values for a multiplex PCR detecting BCR::ABL1 in chronic myeloid leukemia patients on tyrosine kinase inhibitor therapy in resource-limited settings

The prognosis of chronic myeloid leukemia (CML) on tyrosine kinase inhibitor (TKI) treatment is based on the quantification of BCR::ABL1 fusion gene transcript copy number, harmonized by an international scale (IS) based on TaqMan-based real-time quantitative PCR (qRT-PCR). In Ethiopia, as in most low- and middle-income countries (LMICs), access to standard diagnostic, follow-up, and prognostic tools is very limited, and it has been challenging to strictly follow international guidelines. This seriously compromises clinical outcome, despite the availability of TKIs through the Glivec International Patient Assistance Program (GIPAP). Multiplex PCR (mpx-PCR), conventionally regarded as a "screening tool," offers a potential solution to this problem. A total of 219 samples from confirmed CML patients were assayed. In reference to qRT-PCR, the AUC of ROC curve for mpx-PCR was 0.983 (95% CI: 0.957 to 0.997). At the optimum cut-off value, equivalent to BCR::ABL1 (IS) transcript copy number of 0.6%, the specificity and sensitivity were 93% and 95%, respectively, with 94% accuracy. Albeit the sensitivity and accuracy of mpx-PCR decrease below the optimum cutoff of 0.6% (IS), the specificity at 0.1% (IS) was 100%, making it an attractive means to rule-out relapse and drug non-adherence at later stages of treatment, which is particularly an issue in a low income setting. We conclude that the relative simplicity and low cost of mpx-PCR and prognostic relevant cutoff values (0.1-0.6% IS) should allow its use in peripheral clinics and thus maximize the positive impact of TKIs made available through GIPAP in most LMICs.

Telomere loss is accompanied by decreased pool of shelterin proteins TRF2 and RAP1, elevated levels of TERRA and enhanced glycolysis in imatinib-resistant CML cells

Telomere length may be maintained by telomerase nucleoprotein complex and shelterin complex, namely TRF1, TRF2, TIN2, TPP1, POT1 and RAP1 proteins and modulated by TERRA expression. Telomere loss is observed during progression of chronic myeloid leukemia (CML) from the chronic phase (CML-CP) to the blastic phase (CML-BP). The introduction of tyrosine kinase inhibitors (TKIs), such as imatinib (IM), has changed outcome for majority of patients, however, a number of patients treated with TKIs may develop drug resistance. The molecular mechanisms underlying this phenomenon are not fully understood and require further investigation. In the present study, we demonstrate that IM-resistant BCR::ABL1 gene-positive CML K-562 and MEG-A2 cells are characterized by decreased telomere length, lowered protein levels of TRF2 and RAP1 and increased expression of TERRA in comparison to corresponding IM-sensitive CML cells and BCR::ABL1 gene-negative HL-60 cells. Furthermore, enhanced activity of glycolytic pathway was observed in IM-resistant CML cells. A negative correlation between a telomere length and advanced glycation end products (AGE) was also revealed in CD34⁺ cells isolated from CML patients. In conclusion, we suggest that affected expression of shelterin complex proteins, namely TRF2 and RAP1, TERRA levels, and glucose consumption rate may promote telomere dysfunction in IM-resistant CML cells.

Severe persistent marrow aplasia in chronic myeloid leukemia (CML): An unusual complication of imatinib

Background

Imatinib has changed the treatment of chronic myeloid leukemia (CML) drastically since 15 years. It is usually well tolerated, but severe persistent marrow aplasia is an unusual complication of imatinib while using it in CML. The aim of this study is to describe our experience confronting this rare side effect and review the available data worldwide.

Patients and Methods

It was a retrospective analysis conducted at a center from February 2002 to February 2015. This study was endorsed by our Institutional Review Board (IRB) and written consent was taken from all patients. Patients diagnosed as Philadelphia (Ph) chromosome-positive CML either in chronic phase (CP), accelerated phase (AP), or blastic crisis (BC) were included. There were a total of 1,576 patients with CML treated with imatinib during this period. Karyotyping and quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) were done at the time of pancytopenia for all patients.

Results

In total, 11 (males = 5, females = 6) patients met our inclusion criteria from 1,576 patients of CML. The median age was 58 years (range 32-76). Out of 11 patients 8, 2, and 1 patients were in CP, AP, and BC phases, respectively. The median time of administration of imatinib was 3.3 months (range 1.5-6). The average time of marrow recovery was 10.4 months (range 5-15). Two patients expired (one from septicemia and the other from intracranial hemorrhage). BCR-ABL transcripts level by RT-PCR revealed the existence of the disease in all patients.

Conclusion

Imatinib is a very well-tolerated tyrosine kinase inhibitor (TKI), but is associated with persistent myelosuppression when used in older age, advanced phase of the disease, and treated previously. After confirming persistent marrow aplasia, the treatment is mainly supportive. It is striking that the disease is still persistent, which is confirmed by RT-PCR. There is no consensus regarding recalling imatinib at lower doses or the use of second-generation TKI (nilotinib, dasatinib) in these patients.

Developing therapeutic approaches for chronic myeloid leukemia: a review

Modern clinical therapy of chronic myeloid leukemia (CML) with TKIs is highly efficacious in most CML patients, while it is not remedial and generally confined due to intolerance or resistance. CML is currently considered a severe disease. Interestingly, stem cell transplantation in the past decade was an attractive clinical therapeutic option in CML patients, but it is not successful due to independently more death rates in older patients. So, the targeting of BCR::ABL oncoprotein is extensively used to enhance the reduction in a higher percentage of CML patients by tyrosine kinase inhibitors (TKIs). However, resistance or intolerance responses to these inhibitors are responsible for future deterioration and further development of disease. At this point, the clinical treatment of CML is a major challenge, and the lack of molecular responses to TKIs are not succeeded with chemotherapy alone. So, the considerable efficacious clinical necessities remain unmet. Therefore, continuous efforts are needed to explore new potential treatment strategies with an increasing understanding of CML biology. Therefore, this review deals with the investigation of TKI treatment with interferon, chemotherapy (Hydroxyurea, Homoharringtonine, Omacetaxine, Cytarabine), and several other new TKIs under beneficial clinical trials. Additionally, the approaches towards TKIs-resistant or intolerant CML cells where the respective signaling pathway gets up-regulated are also targeted with its inhibitor. This review presents evidence that new TKIs under clinical and pre-clinical trials may improve the chemotherapy of CML.

Deep sequencing reveals the spectrum of BCR-ABL1 mutations upon front-line therapy resistance in chronic myeloid leukemia: An Eastern-Indian cohort study

The course of clinical management in chronic myeloid leukemia (CML) often faces a road-block in the form of front-line (imatinib) therapy resistance. Subsequently, several hotspot mutations were clinically validated in the kinase domain (KD) of BCR-ABL1, in deterring imatinib sensitivity and further, made targeted by next-generation tyrosine-kinase-inhibitor (TKI) drugs. Identifying KD mutations, occurring even at low frequencies, became pertinent here. Globally, cohorts from different origins were tested and the mutational spectra were mapped to categorize clinical management as well as related pathological features of CML. Moreover, targeted deep sequencing could reveal the mutational landscape more efficiently than the less sensitive Sanger sequencing method. However, no such efforts were reported from Eastern Indian cohorts of imatinib-resistant CML-sufferers. This study assessed a prospective study cohort of imatinib-resistant CML cases from Eastern India. Following dissecting the molecular and clinical parameters, the mutational spectrum was comparatively examined using conventional Sanger and next-generation deep sequencing method. This cohort showed a prevalence of e14a2-p210 variant of BCR-ABL1 and acquired resistance against imatinib, while the disease was mostly confined in its chronic phase. Together with a few common hotspot mutations identified in this cohort, deep sequencing revealed cases with a candidate mutation, otherwise undetermined by Sanger method. Also, cases with a second low frequency mutation were identified upon applying deep sequencing. Along with highlighting a few aspects of CML biology employing an Eastern-Indian cohort, this data could mark the immense importance of deep sequencing to contribute in the clinical management of CML upon front-line therapy resistance.

[Survey and analysis of the concerns of patients with chronic myeloid leukemia in China in 2021]

Objective: To investigate the concerns of adult patients with chronic myeloid leukemia (CML) in the chronic phase receiving tyrosine kinase inhibitor (TKI) therapy in China. Methods: A cross-sectional questionnaire including 23 issues of concern was filled by patients with CML nationwide from August to September 2021. The results were compared with those from 2015 to 2016. Results: Data from 952 questionnaires were analyzed. The five most concerned issues were "TKI-related adverse effects and management" (66%) , "stopping TKI therapy" (46%) , "CML risk assessment" (46%) , "TKI dose reduction" (42%) , and "restrictions in daily life activities" (41%) . Compared with the results from 2015 to 2016, patients paid more attention to "TKI-related adverse effects and management" , "monitoring" , and "interpretation of laboratory reports" (all P<0.01) . Concerns of "TKI reimbursement policies" , "price reduction of TKIs" , and issues related to generic TKIs decreased significantly (all P<0.01) . Multivariate analysis showed that female patients (OR=1.8, 95% CI 1.4-2.5, P<0.001) , elderly patients (OR=1.0, 95% CI 1.0-1.0, P<0.001) , or patients with bachelor's degree or higher (OR=1.8, 95% CI 1.3-2.4, P<0.001) were more concerned with "TKI dose reduction" than others. Patients with a bachelor's degree or higher (OR=1.6, 95% CI 1.2-2.2, P=0.002) paid more attention to "CML risk assessment" , whereas those currently receiving a second- or third-generation TKI therapy (OR=1.9, 95% CI 1.3-2.6, P<0.001) were more concerned about "TKI resistance" . Conclusion: Patients with CML paid the most attention to "TKI-related adverse effects and management" , "stopping TKI therapy" , "CML risk assessment" , "TKI dose reduction" , and "restrictions in daily life activities" . Patients' sociodemographic covariates and treatment status were associated with their concerns.

The prognostic role of NKG2A expression for patients with chronic myeloid leukemia after treatment discontinuation

This study aims to evaluate the possibility of tyrosine kinase inhibitors (TKIs) discontinuation in chronic myeloid leukemia (CML) patients who obtained sustained deep molecular response (DMR) and to explore the prognostic role of NK cells in treatment-free remission (TFR). Sixty CML patients who discontinued TKI treatment were enrolled, and we also investigated the immune profiles in 27 CML patients after TKI cessation. Of the 60 patients, the estimated TFR rate was 60.8% [95% CI: 49.5-74.8%] at 12 months. Patients who had longer TKI duration, major molecular response, and DMR maintenance time had a significantly higher TFR rate. And a higher percentage of NKG2A⁺NK cells and NKG2A⁺CD56^brightCD16^-NK cells were independent prognostic factors of TFR in multivariate analysis. These results indicate the practicality of the cessation of TKIs and patients with stable NK cell counts accompanied by higher cytotoxicity and increased killing capacity are more inclined to get sustained treatment-free survival.

Late Responses in Patients With Chronic Myeloid Leukemia Initially Refractory to Tyrosine Kinase Inhibitors

BACKGROUND

The introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved outcomes for patients with chronic myeloid leukemia (CML); however, the prognosis for those who do not meet treatment milestones remains guarded. Here, we report our experience of patients with CML treated at a single center who did not achieve a complete cytogenetic response (CCyR) at 24 months.

METHODS

We retrospectively evaluated 305 patients who were diagnosed with CML at the University of Michigan between 2001 and 2014 and were treated with TKIs. We assessed rates of CCyR at 24 months correlated to clinical outcomes.

RESULTS

The majority of patients (79%) achieved CCyR at 24 months and were classified as responders. At a median follow-up of 8.1 years from TKI initiation, overall survival among responders was significantly greater than nonresponders (93% vs. 85%, P < .001). Progression to blast phase was more common in nonresponders (1.9% vs. 10.4%, P = .004). However, 34% of nonresponders (at 24 months) went on to achieve CCyR with continued TKI therapy.

CONCLUSION

Here, we re-demonstrate the importance of early CCyR in predicting survival and prevention of progression to blast phase. In addition, late CCyR appears to have prognostic implications, and continued TKI therapy with the goal of achieving a later CCyR may be a reasonable strategy in patients with limited alternate treatment options.

A bis-pyridinium fullerene derivative induces apoptosis through the generation of ROS in BCR-ABL-positive leukemia cells

A fusion protein, Breakpoint cluster region-Abelson (BCR-ABL) is responsible for the development of chronic myeloid leukemia (CML) and acute lymphocytic leukemia (ALL). Inhibitors against BCR-ABL are effective for the treatment of leukemia; however, a gatekeeper mutation (T315I) in BCR-ABL results in resistance to these inhibitors, which markedly impedes their efficacy. We herein demonstrated that a bis-pyridinium fullerene derivative (BPF) significantly induced apoptosis in human CML-derived K562 cells and ALL-derived SUP-B15 cells via the generation of reactive oxygen species (ROS). BPF reduced the expression of Bcr-Abl mRNA by inhibiting expression of c-Myc through ROS production. BPF also accelerated protein degradation of BCR-ABL through ROS production. Furthermore, BPF down-regulated the expression of not only BCR-ABL but also T315I-mutated BCR-ABL in ROS-dependent manner. As a result, BPF effectively induced apoptosis in transformed Ba/F3 cells expressing both BCR-ABL and T315I-mutated BCR-ABL. Collectively, these results indicate the potential of BPF as an effective leukemia drug that overcomes resistance to BCR-ABL inhibitors.

Chronic myeloid leukemia stem cells: targeting therapeutic implications

Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm driven by BCR-ABL1 oncoprotein, which plays a pivotal role in CML pathology, diagnosis, and treatment as confirmed by the success of tyrosine kinase inhibitor (TKI) therapy. Despite advances in the development of more potent tyrosine kinase inhibitors, some mechanisms particularly in terms of CML leukemic stem cell (CML LSC) lead to intrinsic or acquired therapy resistance, relapse, and disease progression. In fact, the maintenance CML LSCs in patients who are resistance to TKI therapy indicates the role of CML LSCs in resistance to therapy through survival mechanisms that are not completely dependent on BCR-ABL activity. Targeting therapeutic approaches aim to eradicate CML LSCs through characterization and targeting genetic alteration and molecular pathways involving in CML LSC survival in a favorable leukemic microenvironment and resistance to apoptosis, with the hope of providing a functional cure. In other words, it is possible to develop the combination therapy of TKs with drugs targeting genes or molecules more specifically, which is required for survival mechanisms of CML LSCs, while sparing normal HSCs for clinical benefits along with TKIs.

Simvastatin potentiates the cell-killing activity of imatinib in imatinib-resistant chronic myeloid leukemia cells mainly through PI3K/AKT pathway attenuation and Myc downregulation

Constitutively activated BCR-ABL kinase is considered the driver event responsible in the initiation and development of chronic myeloid leukemia (CML). The advent of the first BCR-ABL inhibitor imatinib has significantly improved the clinical outcome of CML cases. However, resistance to imatinib occurs in 25-30% of CML patients. Due to the lack of effective therapeutic strategies, novel treatment approaches are urgently required for imatinib-resistant CML. Simvastatin, a well-known HMG-CoA reductase inhibitor that confers tremendous clinical benefits in cardiovascular diseases, has attracted mounting attentions for its potent antitumor effects on multiple tumor types. In this study, we demonstrated that simvastatin monotherapy was effective in diminishing cell viability in both imatinib-sensitive and imatinib-resistant CML cells, including T351I mutated cells, with the latter being less vulnerable to the simvastatin than the former. Notably, we found that simvastatin acted as a robust cytotoxic sensitizer of imatinib to kill imatinib-resistant and T315I mutated CML cells in vitro and in vivo. Mechanistically, the cooperative interaction of simvastatin and imatinib was associated with the inactivation of the PI3K/Akt signaling pathway, which was a classical downstream pro-survival cascade of the BCR-ABL kinase. In addition, this drug combination obviously decreased Myc expression through attenuation of canonical Wnt/β-catenin signaling and increased H3K27 trimethylation. Taken together, we provide attractive preclinical results for the combinatorial regimen of simvastatin and imatinib against imatinib-resistant and T315I mutated CML cells. This combined regimens warrants further clinical investigations in patients with imatinib-resistant CML.

[What is the best treatment for chronic-phase CML?]

The chronic myeloid leukemia (CML) therapeutic landscape has dramatically changed with the development of tyrosine kinase inhibitors (TKIs), which allows for a near-normal life expectancy. Five TKIs have been currently approved for CML treatment in Japan, of which four have been indicated as first-line therapy (i.e., imatinib, nilotinib, dasatinib, and bosutinib). Nowadays, the long-term prognosis of patients with CML is determined not by the primary disease but rather by the comorbidities and treatment-related adverse events (AEs), including cardiovascular events. Assessment of risk profile and comorbidities at diagnosis is essential for the appropriate choice of TKI and long-term survival management. The ability of some patients who achieve deep molecular responses to discontinue therapy successfully is well documented. Long-term treatment-free remission with continued response to TKI therapy is now recognized as the most optimal treatment benefit for some patients.This article discusses treatment strategies, AE management, and future perspectives based on the latest CML treatment guidelines.

Long-Term Outcome of Philadelphia Chromosome Positive Leukemia From Eastern Indian Subcontinent: An Experience in the Era of Tyrosine Kinase Inhibitor (TKI) Therapy

INTRODUCTION

Philadelphia chromosome (Ph) marks a group of leukemia with almost all cases of chronic myeloid leukemia (CML), a subset of acute lymphoid leukemia (ALL) and rare cases of acute myeloid leukemia (AML). In the era of precision medicine, such cases are successfully managed with tyrosine kinase inhibitor (TKI) drugs. This study examined the features and long-term outcome of Ph+ve cases from a tertiary cancer care center from Eastern Indian subcontinent.

MATERIALS AND METHODS

Reviewing retrospective case-records registered between 2005 and 2015, cases of CML and ALL were documented under Ph+ve category; while no instance of Ph+ve AML was found.

RESULTS

In CML cohort, adult and juvenile incidences were 95.2% and 4.8% respectively; in ALL cohort, the same was found for 66.67% and 33.33% cases. Among the CML cases, 10-year overall survival (OS) and progression-free survival (PFS) were significantly affected upon the phase of disease at time of detection. Furthermore, both OS and PFS significantly dropped whenever non-TKI-based treatment was applied prior to TKI-commencement. Long-term (10-year) sensitivity to 1st generation TKI, imatinib, was noted 88.51% and 83.33% for adult and juvenile CML cohorts, respectively. For Ph+ ALL cohort, the OS was benefitted upon combinatorial TKI and chemotherapy. However, large fractions of affected individual from CML as well as ALL cohorts were found to discontinue follow-up.

CONCLUSION

Together with differences in outcome on the basis of drug-use from onset, age (juvenile versus adult) and stage at diagnosis, our analyses bring forward the real-world scenario of Ph+ve leukemia managed with precision medicine.

BCR-ABL1 positive AML or CML in blast crisis? A pediatric case report with inv(3) and t(9;22) in the initial clone

The co-occurrence of an inversion inv(3)(q21q26)/GATA2-MECOM and a Philadelphia translocation t(9;22)(q34;q11)/BCR-ABL1 in the context of chronic myeloid leukemia (CML) in blast crisis or acute myeloid leukemia (AML) has only rarely been described. To our knowledge, this co-occurrence has been reported in six pediatric patients with CML but not in pediatric patients with AML. Here, we report on a 7-year-old girl, who, presented with a t(9;22) and inv(3) in 14 of 15 metaphases and an additional monosomy 7 was detected in 5 of these metaphases (ISCN: 46,​XX,​inv(3)(q21q26),​t(9;22)(q34q11)[9]/45,​idem,​-7[5]/46,​XX[1]). The p190 BCR-ABL1 fusion transcript was detected by multiplex PCR and targeted RNA sequencing. Due to these results, a clear distinction between a CML in blast crisis and a BCR-ABL1 positive AML was not possible. The patient was treated according to the treatment recommendations of the AML-BFM study group and additionally received tyrosine kinase inhibitor therapy (Dasatinib). The treatment with Dasatinib was successful in eliminating the inv(3)/t(9;22) clone, but the ancestral inv(3) clone persisted. Based upon these findings we diagnosed an AML with inv(3) and a secondary acquisition of t(9;22). This treatment as well as an allogenic transplantation has led to a complete remission of the disease up to this date (21 months post diagnosis).

Tyrosine kinase inhibitor resistance: a case report on chronic myeloid leukemia and Gilbert's syndrome

Although tyrosine kinase inhibitors (TKI) are commonly used as targeted treatment options for chronic myeloid leukemia (CML), its use is associated to UGT1A1 polymorphisms and, consequently, are related to a higher risk of manifesting Gilbert's syndrome, a genetic disorder associated to hyperbilirubinemia. The report of concomitant condition of CML and Gilbert's Syndrome is uncommon. Therefore, the aim of this study was to report the clinical case of a patient diagnosed with CML and subsequently, with Gilbert's Syndrome. A 34-year-old female was diagnosed with CML. On physical examination, spleen and liver were palpable, indicating hepatosplenomegaly. Laboratory findings of peripheral blood showed leukocytosis (165,190/mm³), 6% of blasts and a bone marrow biopsy showed hypercellularity by granulocytic series with moderate maturation delay. After diagnosis, the patient immediately started chemotherapy with the TKI Imatinib. One year after treatment, due to the partial response, the therapy was changed to Nilotinib, resulting in a complete response. Despite the absence of hyperbilirubinemia, a genetic study by polymerase chain reaction (PCR) verified a positivity for Gilbert's Syndrome. TKIs are also inhibitors of the enzyme UDPGT1, leading to deficient glucuronidation, causing manifestation of Gilbert's Syndrome. This report demonstrates the case of a patient that, besides having two coexisting conditions that could cause hyperbilirubinemia, did not have bilirubin alterations and it highlights the importance of having genetic investigations in cancer patients, in order to identify secondary diseases that could worsen the course of treatment.

Association of tuberculosis in patients with chronic myeloid leukemia: a treatment proposal based on literature review

Introduction: Chronic Myeloid leukemia (CML) is one of the first hematological malignancy linked with genetic alterations and have a targeted therapy with Tyrosine Kinase Inhibitors. However, there are certain unanswered questions and many unmet needs which limit its treatment. Concurrent Mycobacterium Tuberculosis (Mtb) infection is one of those significant factors. Tuberculosis (TB) is a highly prevalent disease in association with diabetes mellitus, malignancy, poor socioeconomic environment, HIV, and other immunosuppressive conditions in developed and developing countries. Anti-TB medications can affect other drug's pharmacokinetics by altering liver enzymes metabolism and poses treatment challenge with CML medications.Areas covered: The authors performed a rigorous literature review between 2000 and 2020 using PubMed and Google Scholar, with the main focus on all articles addressing the topic of TB in CML. Authors highlighted the need to improve clinical diagnosis and to define management strategy for this dilemma.Expert opinion: In the current era, there are no clear guidelines or recommendations in the literature that address this problem. The aim of this review was to collect and carefully analyze the literature to highlight the need for comprehensive guidelines and propose an algorithm for better management of TB in patients with CML.

Application of ZnO/CNT@Fe3O4nanocomposite in amplifying the anti-leukemic effect of imatinib: a novel strategy to adjuvant therapy in chronic myeloid leukemia

The advent of tyrosine kinase inhibitors (TKI) in the therapeutic protocols of chronic myeloid leukemia (CML) sparked a flame of hope for patients to finally reach to the milestone of the complete remission. However, by the different mutations bypassing the effectiveness of Imatinib, a powerful impetus has emerged to bring more efficient agents into the field of treatment. The results of the present study declared that the companionship of our synthesized ZnO/CNT@Fe3O4 nanocomposite with Imatinib was able to more efficiently decrease the survival of CML-derived K562 cells probably through inducing reactive oxygen species (ROS)-dependent apoptosis. We also found a superior cytotoxicity in the presence of a well-known autophagy inhibitor, indicating that the apoptotic effect of this treatment was probably enhanced through the suppression of autophagy. Investigating the molecular mechanisms involved in the growth-suppressive effect of ZnO/CNT@Fe3O4-plus-Imatinib clarified that the up-regulation of SIRT1 ceased the progression of the cell cycle, foremost by increasing the expression of p21 and p27 cyclin-dependent kinase inhibitors. Notably, we reported for the first time that either direct or indirect suppression of c-Myc resulted in an enhanced anti-leukemic effect; suggesting that the overexpression of c-Myc could play a contributory role in attenuating the efficacy of ZnO/CNT@Fe3O4-plus-Imatinib in K562. Given to the established efficacy of ZnO/CNT@Fe3O4 in CML cells, our preclinical results suggest that the application of this nanocomposite is an appealing strategy to boost the anti-leukemic effect of TKIs, which should be further studied in combination with other anti-cancer agents either in hematologic malignancies or solid tumors.

Case reports of chronic myeloid leukemia and tuberculosis: Is imatinib the link between the two?

Current standard of care for treatment of CML is based on tyrosine kinase inhibitors (TKI's). Imatinib is most frequently used first line tyrosine kinase inhibitor. Various side effects of TKI's are known, but some may still be unknown. We are reporting three cases of CML who developed tuberculosis while on treatment with imatinib or dasatinib. Two cases developed CNS tuberculosis and other one was tubercular pleural effusion. These cases indicate that imatinib and other TKI's probably interfere with immunological functions and predispose patients for tuberculosis.

Wogonin reverses the drug resistance of chronic myelogenous leukemia cells to imatinib through CXCL12-CXCR4/7 axis in bone marrow microenvironment

Background

In the current study, chronic myeloid leukemia (CML) cells (K562 and KU812) co-cultured with human bone marrow stromal cells (BMSCs) were significantly less sensitive to imatinib (IM). The activation of the CXCL12-CXCR4/7 axis plays an important role in the protective effect of the bone marrow microenvironment (BME) on CML cells. The aim of this study was to investigate whether Wogonin could increase the sensitivity of CML cells to IM when they were co-cultured with BME and explore its underlying mechanism.

Methods

A model of CML cells co-cultured with BMSCs was applied in vitro. Flow cytometric, western blotting, immunofluorescence, and RT-PCR assays were used to explore the protective effects of BME on CML cells.

Results

The results showed that Wogonin could reverse the resistance of CML cells to IM under co-culture conditions by inhibiting Transforming growth factor-β (TGF-β) secretion in the BME, preventing the translocation of Smad4 into nucleus and subsequently reducing the expression of CXCR4 and CXCR7 in CML cells. Moreover, the reverse effect of Wogonin was demonstrated by inhibiting the activation of CXCL12-CXCR4/7 axis via restraining the TGF-β/Smad4/Id3 pathway in vitro. In vivo studies also showed that Wogonin decreased the expression of CXCR4 and CXCR7 in mice bone marrow with low systemic toxicity, and the mechanism was consistent with the in vitro study.

Conclusions

Wogonin increases the sensitivity of CML cells to IM in BME by controlling the TGF-β/Smad4/Id3 pathway and decreasing the expression of CXCR4 and CXCR7. These results co-supported the point that Wogonin could be a potential candidate of reversal agents on treatment of IM-resistant CML.

Allelic polymorphisms of KIRs and antitumor immunity against chronic myeloid leukemia

The development of BCR-ABL1 tyrosine kinase inhibitors (TKIs) markedly improved the prognosis of patients with chronic myeloid leukemia (CML). Approximately 50% of patients who achieve deep molecular response (DMR) remain in treatment-free remission (TFR) even after discontinuation of TKIs. Although TKIs may achieve clinical "cure" after TKI treatment for specific periods, there are no reliable biomarkers for predicting the response to TKIs and the probability of TFR in CML. An increase in natural killer (NK) cells in the peripheral blood of TKI-treated CML patients is correlated with better outcomes, suggesting that TKIs induce antitumor NK cell immunity against CML cells. Killer immunoglobulin-like receptors (KIRs) are highly polymorphic NK cell receptors that play important roles in the regulation of immune responses. The identification of allelic polymorphisms of KIRs by next-generation sequencing uncovered novel aspects of KIRs. Here we summarize the current knowledge of the genetic and immunological aspects of KIRs and discuss the association between allelic polymorphisms of KIRs and TKI-treated CML.

Separase activity distribution can be a marker of major molecular response and proliferation of CD34+ cells in TKI-treated chronic myeloid leukemia patients

Separase, a cysteine endopeptidase, is a key player in mitotic sister chromatid separation, replication fork dynamics, and DNA repair. Aberrant expression and/or altered separase proteolytic activity are associated with aneuploidy, tumorigenesis, and disease progression. Since genomic instability and clonal evolution are hallmarks of progressing chronic myeloid leukemia (CML), we have comparatively examined separase proteolytic activity in TKI-treated chronic phase CML. Separase proteolytic activity was analyzed on single cell level in 88 clinical samples and in 14 healthy controls by a flow cytometric assay. In parallel, BCR-ABL1 gene expression and replication fork velocity were measured by qRT-PCR and DNA fiber assays, respectively. The separase activity distribution (SAD) value indicating the occurrence of MNCs with elevated separase proteolytic activity within samples was found to positively correlate with BCR-ABL1 gene expression levels and loss of MMR (relapse) throughout routine BCR-ABL1 monitoring. Analyses of CD34⁺ cells and MNCs fractionized by flow cytometric cell sorting according to their separase activity levels (H- and L-fractions) revealed that CD34⁺ cells with elevated separase activity levels (H-fractions) displayed enhanced proliferation/viability when compared with cells with regular (L-fraction) separase activity (mean 3.3-fold, p = 0.0011). BCR-ABL1 gene expression positivity prevailed in MNC H-fractions over L-fractions (42% vs. 8%, respectively). Moreover, expanding CD34⁺ cells of H-fractions showed decreased replication fork velocity compared with cells of L-fractions (p < 0.0001). Our data suggests an association between high separase activity, residual BCR-ABL1 gene expression, and enhanced proliferative capacity in hematopoietic cells within the leukemic niche of TKI-treated chronic phase CML.

Characterizing false-positive fluorescence in situ hybridization results by mate-pair sequencing in a patient with chronic myeloid leukemia and progression to myeloid blast crisis

Traditional cytogenetic testing methodologies, including conventional chromosome analysis and fluorescence in situ hybridization (FISH), are invaluable for the detection or recurrent genetic abnormalities in various hematologic malignancies. However, technological advances, including a novel next-generation sequencing technique termed mate-pair sequencing (MPseq), continue to revolutionize the field of cytogenetics by enabling the characterization of structural variants at a significantly higher resolution compared to traditional methodologies. To illustrate the power of MPseq, we present a 27-year-old male diagnosed with chronic myeloid leukemia in myeloid blast crisis with multiple chromosomal abnormalities observed in all 20 metaphases from a peripheral blood specimen, including t(9;22)(q34;q11.2) and t(4;11)(q12;p15). Suspicious of a novel NUP98/PDGFRA fusion [t(4;11)(q12;p15)], break-apart FISH probe sets for the PDGFRA (4q12) and NUP98 (11p15.4) gene regions were performed and were both positive in approximately 86% of 200 interphase nuclei. However, subsequent MPseq testing revealed breakpoints located within the NUP98 gene and within an intergenic region (4q12) located between the CHIC2 and PDGFRA genes, indicating this 4;11 translocation does not result in the predicted NUP98/PDGFRA gene fusion as inferred from FISH and conventional chromosome results. This case demonstrates the clinical utility of MPseq, particularly for characterizing novel gene fusion events which may ultimately identify a false-positive FISH result.

Inhibition of Xanthine Oxidoreductase Enhances the Potential of Tyrosine Kinase Inhibitors against Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is characterized by the expression of the oncogenic kinase BCR-ABL. Although tyrosine kinase inhibitors (TKIs) against BCR-ABL represent the standard therapeutic option for CML, resistances to TKIs can be a serious problem. Thus, the search for novel therapeutic approaches is still needed. CML cells show an increased ROS production, which is required for maintaining the BCR-ABL signaling cascade active. In line with that, reducing ROS levels could be an interesting therapeutic strategy for the clinical management of resistant CML. To analyze the therapeutic potential of xanthine oxidoreductase (XOR) in CML, we tested the effect of XOR inhibitor allopurinol. Here, we show for the first time the therapeutic potential of allopurinol against BCR-ABL-positive CML cells. Allopurinol reduces the proliferation and clonogenic ability of the CML model cell lines K562 and KCL22. More importantly, the combination of allopurinol with imatinib or nilotinib reduced cell proliferation in a synergistic manner. Moreover, the co-treatment arms hampered cell clonogenic capacity and induced cell death more strongly than each single-agent arm. The reduction of intracellular ROS levels and the attenuation of the BCR-ABL signaling cascade may explain these effects. Finally, the self-renewal potential of primary bone marrow cells from CML patients was also severely reduced especially by the combination of allopurinol with TKIs. In summary, here we show that XOR inhibition is an interesting therapeutic option for CML, which can enhance the effectiveness of the TKIs currently used in clinics.

Reconstitution of NK cells expressing KIR3DL1 is associated with reduced NK cell activity and relapse of CML after allogeneic hematopoietic stem cell transplantation

Although the prognosis of chronic myeloid leukemia (CML) in blastic crisis remains poor, some patients achieve long-term remission after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This may be attributable to graft-versus-leukemia (GVL) effects by donor lymphocytes, but their regulating mechanisms are unclear. Antitumor natural killer (NK) cell immunity is assumed to be important in CML, and we have previously shown that allelic polymorphisms of killer immunoglobulin-like receptors (KIRs) and histocompatibility leukocyte antigens (HLAs) are associated with the response of CML to tyrosine kinase inhibitors. Here, we report a case of CML in blastic phase who received HLA-matched but KIR3DL1 allelic-mismatched allo-HSCT. After transplant, decreased BCR-ABL transcript levels and enhanced NK cell activity were transiently observed. However, reconstitution of KIR3DL1-expressing NK cells occurred, which was associated with diminished NK cell activity and increased BCR-ABL. This case indicates the potential significance of KIR3DL1 in NK cell-mediated GVL activity following allo-HSCT. To the best of our knowledge, this is the first report to analyze the association between sequential KIR3DL1 expression and activity of NK cells after allo-HSCT. Selecting donors with KIR3DL1-null alleles may maintain competent GVL effects and provide improved outcomes in allo-HSCT for CML.

siRNA-mediated BCR-ABL silencing in primary chronic myeloid leukemia cells using lipopolymers

Despite development of effective tyrosine kinase inhibitors for treatment of chronic myeloid leukemia (CML), some patients do not effectively respond to the therapy and can display resistance in response to the drug therapy. To develop an alternative approach to CML therapy, we are exploring siRNA mediated silencing of the primary CML oncogene, BCR-ABL, by using non-viral (polymeric) delivery systems. In this study, a group of lipopolymers derived from low molecular PEIs substituted with linoleic acid (LA), α-linolenic acid (αLA) and cholesterol (Chol) was investigated for the first time for siRNA delivery to CML primary samples. The delivery efficiency in primary cells was equivalent to CML K562 cell line, and the lipopolymers gave effective internalization of siRNA depending on the nature of lipid substituent. The PEI-αLA (2.5 αLA/PEI), PEI-Chol (2.2 Chol/PEI), and PEI-LA (2.6 LA/PEI) lipopolymers used as BCR-ABL siRNA carriers (at 60 nM siRNA) reduced the BCR-ABL mRNA expression by 17% to 45%, and inhibited the formation of colonies by 24% to 41% in comparison with control siRNA in mononuclear cells. BCR-ABL siRNA treatment reduced the BCR-ABL mRNA expression by 50% in one of two CD34+ samples tested, and combination of BCR-ABL siRNA with imatinib (IM) treatment decreased the colony formation by 65% in one of two samples evaluated. The fact that no single polymer was universally effective in all patient samples may suggest patient-to-patient variability in terms of therapeutic responses to siRNA therapy. These results showed that a low dose of BCR-ABL siRNA could be used with lipopolymers to reduce BCR-ABL mRNA expression, CML cell survival and colony formation. This proof of principle study in CML primary cells can be applied to silencing of other therapeutic targets besides BCR-ABL and a study with larger patient samples is warranted for better identification of effective siRNA carriers.

Lack of association between functional polymorphism of DNA repair genes (XRCC1, XPD) and clinical response in Indian chronic myeloid leukemia patients

The resistance for the tyrosine kinase inhibitors in chronic myeloid leukemia (CML) occurs mainly due to BCR/ABL1 dependent and independent mechanisms. The defective DNA repair due to functional polymorphisms in DNA repair genes, might act as an etiological factor for leukemia progression. The study was carried out to understand the role of DNA repair genes (XRCC1, XPD) polymorphisms in Imatinib mesylate (IM) resistant CML patients. The study was carried out in total 87 CML patients (43 nonresponders-cases and 44 responders) who were treated with Imatinib. The treatment and follow-up was done according to European LeukemiaNet guidelines. The genotyping of selected SNPs were studied using RFLP and confirmed with Sanger sequencing (20%). The statistical analysis was performed using online tools (Socscistatistics and GraphPad InStat software). In our study no significant association was inferred between genotypes of DNA repair genes (XRCC1; rs1799782, rs25487, and XPD; rs13181) and complete cytogenetic response as well as molecular response. However there might be a possibility of association between XRCC1 Arg399Gln genotype AA/GA and cytogenetic response though it is statistically insignificant (p > 0.05). Though none of the genotypes of the DNA repair genes showed association with IM response, near association between XRCC1Arg399Gln genotype and cytogenetic response observed in our study. Hence, large sample size should be studied to establish the association of SNPs of DNA repair genes and IM response. Our study is a novel and important to explain the role of DNA repair genes polymorphisms in IM resistance.

Rearrangement of PDGFRβ gene in a patient with Ph-negative chronic myeloid leukemia t(5;12)(q33;p13) in imatinib mesylate treatment-free remission: a case report

Chronic myeloid leukemia (CML) is a hematologic malignancy, in which more than 95% of CML patients are discovered with the Philadelphia chromosome (Ph) or BCR-ABL rearrangement. Those patients mainly suffer from CML, associating with lack of tyrosine kinase activity and BCR-ABL fusion gene. Here, we reported a patient with Ph-negative CML t(5;12)(q33;p13), accompanying with a rare genetic fusion between the TEL and PDGFRβ genes. We identified a novel TEL-PDGFRβ rearrangement, joining TEL (exon 12) to PDGFRβ (exon 5), resulting in overexpression of PDGFRβ. A promising result was achieved, in which TEL-PDGFRβ fusion gene could not be effectively detected during imatinib treatment, demonstrating complete molecular biologic remission. Thus, multiple tyrosine kinase inhibitors are associated with Ph-negative CML t(5;12)(q33;p13) with TEL-PDGFRβ rearrangement.

Detecting the stable point of therapeutic effect of chronic myeloid leukemia based on dynamic network biomarkers

Background

Most researches of chronic myeloid leukemia (CML) are currently focused on the treatment methods, while there are relatively few researches on the progress of patients’ condition after drug treatment. Traditional biomarkers of disease can only distinguish normal state from disease state, and cannot recognize the pre-stable state after drug treatment.

Results

A therapeutic effect recognition strategy based on dynamic network biomarkers (DNB) is provided for CML patients’ gene expression data. With the DNB criteria, the DNB with 250 genes is selected and the therapeutic effect index (TEI) is constructed for the detection of individual disease. The pre-stable state before the disease condition becomes stable is 1 month. Through functional analysis for the DNB, some genes are confirmed as key genes to affect the progress of CML patients’ condition.

Conclusions

The results provide a certain theoretical direction and theoretical basis for medical personnel in the treatment of CML patients, and find new therapeutic targets in the future. The biomarkers of CML can help patients to be treated promptly and minimize drug resistance, treatment failure and relapse, which reduce the mortality of CML significantly.

Electronic supplementary material

The online version of this article (10.1186/s12859-019-2738-0) contains supplementary material, which is available to authorized users.

Analysis of major BCR-ABL1 mRNA by digital polymerase chain reaction is useful for prediction of international scale

BACKGROUND

Major BCR-ABL1 mRNA in patients with chronic myeloid leukemia (CML) has generally been analysed by real-time polymerase chain reaction (PCR). Application of the international scale (IS) for the quantification of major BCR-ABL1 mRNA has been recommended in several sets of guidelines, including those of the European LeukemiaNet. The aim of this study was to clarify the efficacy of digital PCR technology for the IS of BCR-ABL1 mRNA in the patients with CML by comparing with real-time PCR.

METHODS

The analysis of BCR-ABL1 mRNA was carried out by the Ipsogen^® BCR-ABL1 Mbcr IS-MMR DX Kit (Qiagen), and the QuantStudio 3D Digital PCR System (Thermo Fisher Scientific‎) using 20 peripheral blood samples obtained from the 9 patients with CML at Sapporo Medical University Hospital.

RESULTS

The correlation between the data obtained by digital PCR and by real-time PCR was really high at R = 0.96. The detection limit of digital PCR was up to 0.003% and was equal to IS with 0.01% or less in comparison with real-time PCR.

CONCLUSIONS

Digital PCR technology is promising for predicting the IS value with similar efficacy to real-time PCR and should be useful for simple monitoring of the effects of tyrosine kinase inhibitor (TKI) treatments.

Optimization of combination therapy for chronic myeloid leukemia with dosing constraints

In this work, we demonstrate a mathematical technique for optimizing combination regimens with constraints. We apply the technique to a mathematical model for treatment of patients with chronic myeloid leukemia. The in-host model includes leukemic cell and immune system dynamics during treatment with tyrosine kinase inhibitors and immunomodulatory compounds. The model is minimal (semi-mechanistic) with just enough detail that all relevant therapeutic effects can be represented. The regimens are optimized to yield the highest possible reduction in disease burden, taking into account dosing constraints and side effect risks due to drug exposure. We compare the following three types of regimens: (1) regimens that are restricted to certain discrete dose levels, which can only change every three months; (2) optimal regimens determined using optimal control; and (3) regimens that are piecewise-constant like the first type of regimen, but are obtained as approximations to the optimal control regimens. All three types of regimens result in similar outcomes, but the last one is easy to compute in addition to being clinically feasible.

microRNA-199a/b-5p enhance imatinib efficacy via repressing WNT2 signaling-mediated protective autophagy in imatinib-resistant chronic myeloid leukemia cells

Imatinib (IM) is a first-line therapeutic drug for chronic myeloid leukemia (CML), a hematological disease. Mutations in the BCR-ABL domain increase formation of IM resistance in CML. However, not all patients are BCR-ABL domain-mutant dependent. Investigating non-mutant mechanisms in the development of acquired IM resistance is a critical issue. We explored the mechanisms which influence IM efficacy and resistance in CML. Higher protective autophagy was identified in IM-resistant K562 (K562R) cells. Inhibition of autophagy by the inhibitors, chloroquine and 3-methyladenine, enhanced IM's efficacy in K562R cells. In addition, microRNA (miR)-199a/b-5p were downregulated in K562R cells compared to parent cells. Overexpression of miR-199a/b-5p reduced autophagy and induced cell apoptosis, resulting in enhanced IM's efficacy in K562R cells. Moreover, expression levels of the Wingless-type MMTV integration site family member 2 (WNT2), a positive regulator of autophagy, were significantly higher in K562R cells, and it was validated as a direct target gene of miR-199a/b-5p. Overexpressions of miR-199a/b-5p inhibited WNT2 downstream signaling. Furthermore, overexpression and knockdown of WNT2 influenced autophagy formation and CML drug sensitivity to IM. Overexpression of WNT2 could also reverse miR-199a/b-5p-enhanced IM efficacy in K562R cells. These results emphasized that miR-199a/b-5p inhibited autophagy via repressing WNT2 signaling and might provide novel therapeutic strategies for future IM-resistant CML therapy and drug development.

Targeting chronic myeloid leukemia stem cells: can transcriptional program be a druggable target for cancers?

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm resulting from acquisition of constitutively active BCR-ABL protein tyrosine kinase in a hematopoietic stem cell (HSC). Though tyrosine kinase inhibitors (TKIs) have changed a fatal disease into manageable disease, most patients cannot discontinue TKI treatment due to persistence of TKI-resistant leukemia stem cells (LSCs). Much effort has been made to find out factors or pathways specifically operating in LSCs to selectively target LSCs, with some promising results at least in preclinical models. In this article, we briefly review the role of Wnt/β-catenin signaling and its related factors in CML LSCs, especially focusing on Tcf1/Lef1 transcription factors, major effectors of Wnt/β-catenin pathway, of which transcriptional program have recently been shown to be targetable with prostaglandin E1.

Minimal Residual Disease Eradication in CML: Does It Really Matter?

BCR-ABL1 tyrosine kinase inhibitors (TKIs) have improved the prognosis of chronic phase chronic myeloid leukemia (CP-CML) to an extent that survival is largely determined by non-CML mortality. Monitoring for minimal residual disease by measuring BCR-ABL1 messenger RNA is a key component of CML management. CP-CML patients who achieve a stable deep molecular response may discontinue (TKIs) with an ~ 50% chance of entering treatment-free remission (TFR). So far discontinuation of TKIs has largely been limited to clinical trials, but is on the verge of becoming a part of wider clinical practice. Careful patient selection, dense molecular monitoring, and prompt reinstitution of treatment in the event of relapse are all vital to reproduce the same level of success. Much effort has been dedicated to identifying therapeutic strategies to eliminate CML stem cells and enable to TFR in more patients. Unfortunately, despite promising preclinical data, as yet, none of the various approaches have entered clinical practice.

Association between Altered Expression and Genetic Variations of Transforming Growth Factor β-Smad Pathway with Chronic Myeloid Leukemia

Background: Chronic myeloid leukemia (CML) is a hematological disorder caused by fusion of BCR and ABL genes. BCR-ABL dependent and independent pathways play equally important role in CML. TGFβ-Smad pathway, an important BCR -ABL independent pathway, has scarce data in CML. Present study investigate the association between TGFβ-Smad pathway and CML. Materials and Methods: Sixty-four CML patients and age matched healthy controls (n=63) were enrolled in this study. Patients were segregated into responder and resistant groups depending on their response to Imatinib mesylate (IM). TGFβ1 serum levels were evaluated by ELISA and transcript levels of TGFβ1 receptors, SMAD4 and SMAD7 were evaluated by Real-Time PCR. Sequencing of exons and exon-intron boundaries of study genes was performed using Next Generation Sequencing (NGS) in 20 CML patients. Statistical analysis was performed using SPSS version 16.0. Results:TGFβ1 serum levels were significantly elevated (p = 0.02) and TGFβR2 and SMAD4 were significantly down-regulated (p = 0.012 and p = 0.043 respectively) in the patients. c.69A>G in TGFβ1, c.1024+24G>A in TGFβR1 and g.46474746C>T in SMAD7 were the most important genetic variants observed with their presence in 10/20, 8/20 and 7/20 patients respectively. In addition, TGFβR1 transcript levels were reduced in CML patients with c.69A>G mutation. None of the genes differed significantly in terms of expression or genetic variants between responder and resistant patient groups. Conclusion: Our findings demonstrate the role of differential expression and genetic variants of TGFβ-Smad pathway in CML. Decreased TGFβR2 and SMAD4 levels observed in the present study may be responsible for reduced tumor suppressive effects of this pathway in CML.

Chronic Myeloid Leukemia (CML) Mouse Model in Translational Research

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by increased proliferation of granulocytic cells without the loss of their capability to differentiate. CML is a clonal disease, originated at the level of Hematopoietic Stem Cells with the Philadelphia chromosome resulting from a reciprocal translocation between the chromosomes 9 and 22t(9;22)-(q34;q11). This translocation produces a fusion gene known as BCR-ABL which acquires uncontrolled tyrosine kinase activity, constantly turning on its downstream signaling molecules/pathways, and promoting proliferation of leukemia cell through anti-apoptosis and acquisition of additional mutations. To evaluate the role of each critical downstream signaling molecule of BCR-ABL and test therapeutic drugs in vivo, it is important to use physiological mouse disease models. Here, we describe a mouse model of CML induced by BCR-ABL retrovirus (MSCV-BCR-ABL-GFP; MIG-BCR-ABL) and how to use this model in translational research.Moreover, to expand the application of this retrovirus induced CML model in a lot of conditional knockout mouse strain, we modified this vector to a triple gene coexpression vector in which we can co-express BCR-ABL, GFP, and a third gene which will be tested in different systems. To apply this triple gene system in conditional gene knockout strains, we can validate the CML development in the knockout mice and trace the leukemia cell following the GFP marker. In this protocol, we also describe how we utilize this triple gene system to prove the function of Pten as a tumor suppressor in leukemogenesis. Overall, this triple gene system expands our research spectrum in current conditional gene knockout strains and benefits our CML translational research.

Mechanisms of Resistance to ABL Kinase Inhibition in Chronic Myeloid Leukemia and the Development of Next Generation ABL Kinase Inhibitors

Chronic myeloid leukemia is increasingly viewed as a chronic illness; most patients have a life expectancy close to that of the general population. Despite progress made using BCR-ABL1 tyrosine kinase inhibitors (TKIs), drug resistance via BCR-ABL1-dependent and BCR-ABL1-independent mechanisms continues to be an issue. BCR-ABL1-dependent resistance is primarily mediated through oncoprotein kinase domain mutations and usually results in overt resistance to TKIs. However, BCR-ABL1-independent resistance in the setting of effective BCR-ABL1 inhibition is recognized as a major contributor to minimal residual disease. Efforts to eradicate persistent leukemic stem cells have focused on combination therapy.

CALR-positive myeloproliferative disorder in a patient with Ph-positive chronic myeloid leukemia in durable treatment-free remission: a case report

Current diagnostic criteria for Philadelphia-negative myeloproliferative neoplasia (MPN) have been redefined by the discovery of Janus kinase 2 (JAK2), myeloproliferative leukemia (MPL) and calreticulin (CALR) genetic alterations. Only few cases of coexistence of CALR-mutated MPN and Philadelphia-positive chronic myeloid leukemia (CML) have been described so far. Here we report the case of a patient with CML diagnosed in 2001, treated with imatinib and pegylated interferon (IFN) frontline. She reached complete molecular remission (CMR) and discontinued imatinib, maintaining treatment free remission. Due to persistent thrombocytosis, we repeated bone marrow (BM) analysis and diagnosed CARL-mutated essential thrombocythemia (ET). A CALR-positive clone was found to be present since 2001, and was unaffected by imatinib treatment, possibly representing a molecular abnormality arising at stem cell level.

Clonal chromosomal aberrations in Philadelphia negative cells such as monosomy 7 and trisomy 8 may persist for years with no impact on the long term outcome in patients with chronic myeloid leukemia

The appearance of clonal chromosomal aberrations in Philadelphia negative cells (CCA/Ph-) during the treatment of chronic myeloid leukemia (CML) was recently confirmed. Importance of these findings has not been clearly defined. We present data on the time of appearance, persistence, size of the CCA/Ph- clone in terms of drugs used and hematological, cytogenetic and molecular response rates. The focus was on the peripheral blood cytopenias and myelodysplastic changes in the bone marrow microscopic evaluation. In 5 out of 155 (3,2%) CML patients, the persistent presence (up to nine years) of CCA/Ph- was found (monosomy 7 and trisomy 8 in unrelated clones in two patients treated with tyrosine kinase inhibitors; trisomy 8 in two patients on imatinib; trisomy 21 in one patient on interferon alfa treatment). Aberrations were present in median 24% Ph- cells in 3-15 subsequent analyses at different cytogenetic and molecular response time points. No evident myelodysplastic changes nor transformation to MDS/AML occurred in patients with CCA/Ph-. All the patients achieved major molecular response (MMR). It seems that CCA/Ph- presence does not affect the long term outcome in patients with chronic myeloid leukemia. Further complex monitoring of the CML patients with CCA/Ph- is still needed.

Nrf-2/Gst-α mediated imatinib resistance through rapid 4-HNE clearance

The advent of imatinib mesylate (IM) has dramatically improved the outcome of patients with chronic myeloid leukemia, but drug resistance, particularly in advanced stage of disease, portents eventual relapse and progression. To identify the candidate molecule responsible for resistance during IM treatment, an IM-resistant K562 cell line was generated by culturing in gradually increasing dose of IM. The expression of Nrf-2 and its downstream target, Gst-α, were significantly induced in these cells. GST-α, in turn, mediated cell survival by maintaining intracellular low level of 4-HNE. Inhibition of Nrf-2 effectively reduced the expression of Gst-α, resulting in accumulation of 4-HNE and elevated sensitiveness to IM. Moreover, in IM-sensitive K562 cells enforced Gst-α expression strikingly protected cells from the insult of IM. Finally, we also examined the levels of Nrf-2 in clinical bone morrow samples. Nrf-2 and Gst-α were more abundant in bone morrow of CML patients compared with that of healthy donors. In addition, Nrf-2 and Gst-α were further up-regulated in samples of patients with weak response to IM. In conclusion, our study shows that rapid clearance of 4-HNE by Nrf-2/GST may represents a novel molecular basis of IM resistance in CML.

SH2 Domain-Based FRET Biosensor for Measuring BCR-ABL Activity in Living CML Cells

Fluorescent proteins (FPs) displaying distinct spectra have shed their light on a wide range of biological functions. Moreover, sophisticated biosensors engineered to contain single or multiple FPs, including Förster resonance energy transfer (FRET)-based biosensors, spatiotemporally reveal the molecular mechanisms underlying a variety of pathophysiological processes. However, their usefulness for applied life sciences has yet to be fully explored. Recently, our research group has begun to expand the potential of FPs from basic biological research to the clinic. Here, we describe a method to evaluate the responsiveness of leukemia cells from patients to tyrosine kinase inhibitors using a biosensor based on FP technology and the principle of FRET. Upon phosphorylation of the tyrosine residue of the biosensor, binding of the SH2 domain to phosphotyrosine induces conformational change of the biosensor and brings the donor and acceptor FPs into close proximity. Therefore, kinase activity and response to kinase inhibitors can be monitored by an increase and a decrease in FRET efficiency, respectively. As in basic research, this biosensor resolves hitherto arduous tasks and may provide innovative technological advances in clinical laboratory examinations. State-of-the-art detection devices that enable such innovation are also introduced.

CML Mouse Model Generated from Leukemia Stem Cells

Chronic myeloid leukemia (CML) is a myeloproliferative disorder with a high number of well-differentiated neutrophils in peripheral blood and myeloid cells in bone marrow (BM). CML is derived from the hematopoietic stem cells (HSCs) with the Philadelphia chromosome (Ph(+), t(9;22)-(q34;q11)), resulting in generating a fusion oncogene, BCR/ABL1. HSCs with Ph(+) are defined as leukemia stem cells (LSCs), a subpopulation cell at the apex of hierarchies in leukemia cells and responsible for the disease continuous propagation. Several kinds of CML models have been developed to reveal the mechanism of CML pathogenesis and evaluate therapeutic drugs in the past three decades. Here, we describe the procedures to generate a CML mouse model by introducing BCR/ABL1 into Lin(-)Sca1(+) cKit(+) population cells purified from mouse bone marrow. In CML retroviral transduction/transplantation mouse models, this modified model can mimic CML pathogenesis on high fidelity.

Discovering gene expression signatures responding to tyrosine kinase inhibitor treatment in chronic myeloid leukemia

BACKGROUND

Tyrosine kinase inhibitor (TKI)-based therapy is a recommended treatment for patients with chronic myeloid leukemia (CML). However, a considerable group of CML patients do not respond well to the TKI therapy. Challenging to overcome this problem, we tried to discover molecular signatures in gene expression profiles to discriminate the responders and non-responders of TKI therapy.

METHODS

We collected three microarray datasets of CML patients having total 73 responders and 38 non-responders. Statistical analysis was performed to identify differentially expressed genes (DEGs) as gene signature candidates from integrated microarray datasets. The classification performance of these genes and further selected discriminator gene sets was tested by using random forest and iterative backward variable selection methods.

RESULTS

We identified a set of genes including CTBP2, NADK, AZU1, CTSH, FSTL1, and HDLBP showing the highest accuracy more than 69.44 % to classify TKI response in CML patients. Interestingly, four genes of them are on the signaling pathway of cell proliferation. This set of genes showed much higher performance than the average performance of other genes in downstream signaling of TKI target, BCR-ABL.

CONCLUSIONS

In this study, we could find a set of potential companion diagnostic markers for TKI treatment and, at the same time, the potential of gene expression analysis to enhance the coverage of companion diagnostics.

MicroRNA-130a regulates cell malignancy by targeting RECK in chronic myeloid leukemia

Emerging evidence has indicated that microRNAs are involved in tumor development and progression, acting as either tumor suppressors or oncogenes. In this study, we aimed to investigate the role of miR-130a in the pathogenesis of chronic myeloid leukemia (CML). Functional studies indicate that over-expression of miR-130a in A562 CML cells dramatically suppresses cell proliferation and induces cell apoptosis both in vitro and in vivo. Furthermore, we demonstrate that the transcriptional regulator RECK is a target of miR-130a. In conclusion, our study suggests that miR-130a may function as a novel tumor suppressor in CML, and its anti-oncogenic activity may involve the direct targeting and inhibition of RECK.

New Mouse Models to Investigate the Efficacy of Drug Combinations in Human Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) comprises a simple and effective paradigm for generating new insights into the cellular origin, pathogenesis, and treatment of many types of human cancer. In particular, mouse models of CML have greatly facilitated the understanding of the underlying molecular mechanisms and pathogenesis of this disease and have led to the identification of new drug targets that in some cases offer the possibility of functional cure. There are currently three established CML mouse models: the BCR-ABL transgenic model, the BCR-ABL retroviral transduction/transplantation model, and the xenotransplant immunodeficient model. Each has its own unique advantages and disadvantages. Depending on the question of interest, some models may be more appropriate than others. In this chapter, we describe a newly developed xenotransplant mouse model to determine the efficacy of novel therapeutic agents, either alone or in combination. The model facilitates the evaluation of the frequency of leukemic stem cells with long-term leukemia-initiating activity, a critical subcellular population that causes disease relapse and progression, through the utilization of primary CD34(+) CML stem/progenitor cells obtained from CML patients at diagnosis and prior to drug treatment. We have also investigated the effectiveness of new combination treatment strategies designed to prevent the development of leukemia in vivo using BCR-ABL (+) blast crisis cells as a model system. These types of in vivo studies are important for the prediction of individual patient responses to drug therapy, and have the potential to facilitate the design of personalized combination therapy strategies.

Molecular biological characteristics of the recruitment of hematopoietic stem cells from bone marrow niche in chronic myeloid leukemia

Chronic myeloid leukemia (CML) can be contextualized as a disease of unregulated self-renewal of stem cells which exist in a quiescent state and are instructed to differentiate and mobilize to circulation under pathologic circumstances leading to tumor invasion and metastasis. Here we found that matrix metalloproteinase-9 (MMP-9), induced by TGF-β1, upregulated s-KitL and s-ICAM-1, permitting the transfer of c-kit(+) hematopoietic stem cells (HSCs) from the quiescent to proliferative niche in CML. Further study showed that this MMP-9 production was raised by CML specific BCR/ABL(+) oncogene mediated TGF-β1. Besides, phosphatidylinositol-3 kinase (PI3K)/Akt/nuclear factor (NF)-κB signaling pathway was evidenced to govern this stem cell recruitment in CML pathogenesis. Overall, our observations defined a novel critical role for TGF-β1 induced PI3K/Akt/NF-κB signaling pathway in the recruitment of the malignant cells in CML by releasing s-KitL and s-ICAM-1 and this was through a distinct PI3K/Akt/NF-κB signaling pathway.

Preclinical model for identification of therapeutic targets for CML offers clues for handling imatinib resistance

Success of imatinib in chronic myeloid leukemia (CML) therapy has undoubtedly proved utility of signalling molecules as therapeutic targets. However, development of imatinib resistance and progression to blastic crisis are the current challenges in clinics. To develop therapeutic alternatives for CML, understanding of signalling events downstream of bcr-abl might be helpful. Current CML cell lines do not give comprehensive picture of signalling events involved in pathogenesis of CML. Hence, there is a major unmet need for a better preclinical model for CML. Here, we report on development of RIN9815/bcr-abl, a novel cell line model that mimics signalling events in CML PMNL. Studies on crucial signalling molecules i.e., ras, rac, rhoA and actin in this cell line identified rhoA as the key regulator involved in CML cell function as well as proliferation of both, imatinib sensitive and resistant cells. Hence, RIN9815/bcr-abl could serve as the unique preclinical model in understanding pathogenesis of CML and in drug development.

Celecoxib sensitizes imatinib-resistant K562 cells to imatinib by inhibiting MRP1-5, ABCA2 and ABCG2 transporters via Wnt and Ras signaling pathways

Imatinib mesylate, a tyrosine kinase inhibitor, is very effective in the treatment of chronic myeloid leukemia (CML). However, development of resistance to imatinib therapy is also a very common mechanism observed with long-term administration of the drug. Our previous studies have highlighted the role of cyclooxygenase-2 (COX-2) in regulating the expression of multidrug resistant protein-1 (MDR1), P-gp, in imatinib-resistant K562 cells (IR-K562) via PGE2-cAMP-PKC-NF-κB pathway and inhibition of COX-2 by celecoxib, a COX-2 specific inhibitor, inhibits this pathway and reverses the drug resistance. Studies have identified that not only MDR1 but other ATP-binding cassette transport proteins (ABC transporters) are involved in the development of imatinib resistance. Here, we tried to study the role of COX-2 in the regulation of other ABC transporters such as MRP1, MRP2, MRP3, ABCA2 and ABCG2 that have been already implicated in imatinib resistance development. The results of the study clearly indicated that overexpression of COX-2 lead to upregulation of MRP family proteins in IR-K562 cells and celecoxib down-regulated the ABC transporters through Wnt and MEK signaling pathways. The study signifies that celecoxib in combination with the imatinib can be a good alternate treatment strategy for the reversal of imatinib resistance.