Imatinib for newly diagnosed patients with chronic myeloid leukemia: incidence of sustained responses in an intention-to-treat analysis

The growth of K562 human leukemia cells was inhibited by therapeutic neural stem cells in cellular and xenograft mouse models

To confirm the anti-tumor effect of engineered neural stem cells (NSCs) expressing cytosine deaminase (CD) and interferon-β (IFN-β) with prodrug 5-fluorocytosine (FC), K562 chronic myeloid leukemia (CML) cells were co-cultured with the neural stem cell lines HB1.F3.CD and HB1.F3.CD.IFN-β in 5-FC containing media. A significant decrease in the viability of K562 cells was observed by the treatment of the NSC lines, HB1.F3.CD and HB1.F3.CD.IFN-β, compared with the control. A modified trans-well assay showed that engineered human NSCs significantly migrated toward K562 CML cells more than human normal lung cells. In addition, the important chemoattractant factors involved in the specific migration ability of stem cells were found to be expressed in K562 CML cells. In a xenograft mouse model, NSC treatments via subcutaneous and intravenous injections resulted in significant inhibitions of tumor mass growth and extended survival dates of the mice. Taken together, these results suggest that gene therapy using genetically engineered stem cells expressing CD and IFN-β may be effective for treating CML in these mouse models.

Improving Outcomes in Chronic Myeloid Leukemia Over Time in the Era of Tyrosine Kinase Inhibitors

Most patients with chronic myeloid leukemia (CML) receiving treatment with BCR-ABL1 tyrosine kinase inhibitors (TKIs) will achieve favorable responses. Moreover, TKI therapy enables patients to experience long-term survival, with survival rates similar to those of individuals without CML. This enhanced survival has resulted from the availability of multiple BCR-ABL1 TKIs with efficacy, not only in frontline treatment, but, importantly, also in second- and third-line treatment. We have reviewed the changes in long-term outcomes in the era of TKI therapy and how these changes have affected treatment practices. We discuss the development of imatinib, the first BCR-ABL1 TKI, followed by newer TKIs, including nilotinib, dasatinib, bosutinib, and ponatinib. We consider the key studies that led to their development as frontline or later-line therapies, their safety profiles, and their effect on improving patient outcomes. With these improved outcomes, the definition of an optimal response has become more stringent, and treatment monitoring strategies have changed. Second-line patient populations have evolved from those with resistance to, or intolerance of, imatinib to those with moderate responses to, or low-grade adverse events with, imatinib. Although all TKIs are associated with high survival rates, newer TKIs have been associated with lower disease progression rates and, importantly, deeper treatment responses and, potentially, a greater chance of future treatment-free remission. Finally, we consider the unmet needs of patients with CML, including the challenges remaining for those without optimal responses during TKI therapy and new therapies and strategies to identify such patients at diagnosis.

Front-line imatinib treatment in children and adolescents with chronic myeloid leukemia: results from a phase III trial

A total of 156 patients (age range 1.3-18.0 years, median 13.2 years; 91 (58.3%) male) with newly diagnosed CML (N = 146 chronic phase (CML-CP), N = 3 accelerated phase (CML-AP), N = 7 blastic phase (CML-BP)) received imatinib up-front (300, 400, 500 mg/m², respectively) within a prospective phase III trial. Therapy response, progression-free survival, causes of treatment failure, and side effects were analyzed in 148 children and adolescents with complete data. Event-free survival rate by 18 months for patients in CML-CP (median follow-up time 25 months, range: 1-120) was 97% (95% CI, 94.2-99.9%). According to the 2006 ELN-criteria complete hematologic response by month 3, complete cytogenetic response (CCyR) by month 12, and major molecular response (MMR) by month 18 were achieved in 98, 63, and 59% of the patients, respectively. By month 36, 86% of the patients achieved CCyR and 74% achieved MMR. Thirty-eight patients (27%) experienced imatinib failure because of unsatisfactory response or intolerance (N = 9). In all, 28/148 patients (19%) underwent stem cell transplantation (SCT). In the SCT sub-cohort 2/23 patients diagnosed in CML-CP, 0/1 in CML-AP, and 2/4 in CML-BP, respectively, died of relapse (N = 3) or SCT-related complications (N = 2). This large pediatric trial extends and confirms data from smaller series that first-line imatinib in children is highly effective.

Intolerance to tyrosine kinase inhibitors in chronic myeloid leukemia: the possible role of ponatinib

INTRODUCTION

In spite of the proven efficacy of the tyrosine kinase inhibitor (TKI), imatinib, in chronic myeloid leukemia (CML), many patients develop intolerance and discontinue therapy in the long-term. Second-generation TKIs (dasatinib, nilotinib, bosutinib) and the third-generation TKI, ponatinib, have added opportunities but also complexity in the settings of CML treatment.

AREAS COVERED

Different definitions of intolerance have been used through several clinical trials, making the published data non homogenous. In most cases, only the severity of acute adverse events (AEs), graded by conventional scales such as Common Terminology Criteria for Adverse Events, was reported. Limited attention to long-term events or more in general, to the impact of AEs on patient quality of life (QoL), remains a problem. Ponatinib is active against all BCR-ABL1 mutants, including T315I, and is widely used to treat patients who developed resistance to other TKIs in any CML phase; however, only limited data is available on the possible role of ponatinib for intolerant patients.

EXPERT OPINION

We review the different definitions of intolerance used in sponsored trials and in clinical practice, and we discuss how such definitions impact on the management of AEs. We summarize how to evaluate QoL during treatment with TKIs and how to include ponatinib among possible option for intolerant patients.

Transposon-mediated generation of BCR-ABL1-expressing transgenic cell lines for unbiased sensitivity testing of tyrosine kinase inhibitors

Point mutations in the ABL1 kinase domain are an important mechanism of resistance to tyrosine kinase inhibitors (TKI) in BCR-ABL1-positive and, as recently shown, BCR-ABL1-like leukemias. The cell line Ba/F3 lentivirally transduced with mutant BCR-ABL1 constructs is widely used for in vitro sensitivity testing and response prediction to tyrosine kinase inhibitors. The transposon-based Sleeping Beauty system presented offers several advantages over lentiviral transduction including the absence of biosafety issues, faster generation of transgenic cell lines, and greater efficacy in introducing large gene constructs. Nevertheless, both methods can mediate multiple insertions in the genome. Here we show that multiple BCR-ABL1 insertions result in elevated IC₅₀ levels for individual TKIs, thus overestimating the actual resistance of mutant subclones. We have therefore established flow-sorting-based fractionation of BCR-ABL1-transformed Ba/F3 cells facilitating efficient enrichment of cells carrying single-site insertions, as demonstrated by FISH-analysis. Fractions of unselected Ba/F3 cells not only showed a greater number of BCR-ABL1 hybridization signals, but also revealed higher IC₅₀ values for the TKIs tested. The data presented highlight the need to carefully select transfected cells by flow-sorting, and to control the insertion numbers by FISH and real-time PCR to permit unbiased in vitro testing of drug resistance.

The novel anticancer agent JNJ-26854165 is active in chronic myeloid leukemic cells with unmutated BCR/ABL and T315I mutant BCR/ABL through promoting proteosomal degradation of BCR/ABL proteins

Chronic myeloid leukemia (CML) is a clonal malignant disease caused by the expression of BCR/ABL. MDM2 (human homolog of the murine double minute-2) inhibitors such as Nutlin-3 have been shown to induce apoptosis in a p53-dependent manner in CML cells and sensitize cells to Imatinib. Here, we demonstrate that JNJ-26854165, an inhibitor of MDM2, inhibits proliferation and triggers cell death in a p53-independent manner in various BCR/ABL-expressing cells, which include primary leukemic cells from patients with CML blast crisis and cells expressing the Imatinib-resistant T315I BCR/ABL mutant. The response to JNJ-26854165 is associated with the downregulation of BCR/ABL dependently of proteosome activation. Moreover, in all tested CML cells, with the exception of T315I mutation cells, combining JNJ-26854165 and tyrosine kinase inhibitor (TKI) Imatinib or PD180970 leads to a synergistic effect. In conclusion, our results suggest that JNJ-26854165, used either alone or in combination with TKIs, represents a promising novel targeted approach to overcome TKI resistance and improve patient outcome in CML.

Non ABL-directed inhibitors as alternative treatment strategies for chronic myeloid leukemia

The introduction of ABL Tyrosine Kinase Inhibitors (TKIs) has significantly improved the outcome of Chronic Myeloid Leukemia (CML) patients that, in large part, achieve satisfactory hematological, cytogenetic and molecular remissions. However, approximately 15-20% fail to obtain optimal responses according to the current European Leukemia Network recommendation because of drug intolerance or resistance.Moreover, a plethora of evidence suggests that Leukemic Stem Cells (LSCs) show BCR-ABL1-independent survival. Hence, they are unresponsive to TKIs, leading to disease relapse if pharmacological treatment is discontinued.All together, these biological events generate a subpopulation of CML patients in need of alternative therapeutic strategies to overcome TKI resistance or to eradicate LSCs in order to allow cure of the disease.In this review we update the role of "non ABL-directed inhibitors" targeting signaling pathways downstream of the BCR-ABL1 oncoprotein and describe immunological approaches activating specific T cell responses against CML cells.

[Effect of MDR1 and CYP3A5 gene polymorphisms on outcomes of patients receiving imatinib treatment for chronic myeloid leukemia]

OBJECTIVE

To study the effect of MDR1 and CYP3A5 gene polymorphisms on the outcomes of imatinib treatment in patients with chronic myeloid leukemia (CML).

METHODS

A total of 100 patients with CML treated with imatinib were enrolled in this study, including 50 patients with cytogenetic relapse (study group) and 50 without cytogenetic relapse (control group) during the follow-up for 45 months. For all the patients, single nucleotide polymorphisms (SNPs) of C1236T, C3435T, and G2677T/A loci in the MDR1 gene and A6986G locus in CYP3A5 gene were genotyped and the trough levels of imatinib was measured using LC-MS/MS. The relationship between SNPs of the loci and the risk of cytogenetic relapse were analyzed.

RESULTS

The risk of cytogenetic recurrence was significantly higher in patients with CC genotypes of MDR1-C1236T and MDR1-C3435T than in those with CT + TT genotypes (P < 0.05). The median survival time of the patients with TT genotypes of MDR1-C3435T and MDR1-C1236T was significantly higher than that of patients with CC genotypes and CT genotypes (P < 0.05). The incidences of hematologic toxicity and neutropenia were significantly higher in patients with cytogenetic relapse than in those without cytogenetic relapse (P < 0.05). MDR1-C3435T genotype and imatinib concentration were independent predictors of cytogenetic relapse of CML.

CONCLUSIONS

The risk of cytogenetic relapse of CML was significantly affected by SNPs of C1236T and C3435T loci of MDR1 gene and blood imatinib concentration. MDR1-C3435T genotype can be used as a potential biomarker for predicting cytogenetic relapse in CML patients.

Activating Autophagy as a Therapeutic Strategy for Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative disease characterized by Lewy body pathology of which the primary constituent is aggregated misfolded alpha-synuclein protein. Currently, there are no clinical therapies for treatment of the underlying alpha-synuclein dysfunction and accumulation, and the standard of care for patients with Parkinson's disease focuses only on symptom management, creating an immense therapeutic gap that needs to be filled. Defects in autophagy have been strongly implicated in Parkinson's disease. Here, we review evidence from human, mouse, and cell culture studies to briefly explain these defects in autophagy in Parkinson's disease and the necessity for autophagy to be carefully and precisely tuned to maintain neuron survival. We summarize recent experimental agents for treating alpha-synuclein accumulation in α-synuclein Parkinson's disease and related synucleinopathies. Most of the efforts for developing experimental agents have focused on immunotherapeutic strategies, but we discuss why those efforts are misplaced. Finally, we emphasize why increasing autophagy flux for alpha-synuclein clearance is the most promising therapeutic strategy. Activating autophagy has been successful in preclinical models of Parkinson's disease and yields promising results in clinical trials.

Ponatinib: A Third-Generation Inhibitor for the Treatment of CML

The establishment of imatinib as the standard therapy for CML marked the beginning of a new era of treatment. Due to occurring intolerance and resistance against the drug, the development of new inhibitors was promoted. This led to the second-generation inhibitors dasatinib, nilotinib, and bosutinib. Despite all achieved improvements, first- and second-generation inhibitors are ineffective against the BCR-ABL T315I "gatekeeper" mutation. In order to overcome this issue and to further improve the inhibitory effect, the third-generation inhibitor ponatinib was developed. Various clinical trials have been launched to study the effect of ponatinib in the clinical setting. Based on positive phase 1 and phase 2 trials, ponatinib was approved for the second-line treatment of CML and Ph⁺ ALL in December 2012 in the USA and in July 2013 in the European Union. The safety data of these trials particularly revealed a dose-dependent, increased risk for serious arterial occlusive events under treatment with ponatinib. Further trials investigate optimized dosing schemes to reduce side effects while maintaining clinical activity in CML and evaluate potential activity of the drug in other malignancies. In conclusion, ponatinib has proved to be a powerful BCR-ABL inhibitor, which exhibits clinical activity both in BCR-ABL wild-type and mutant CML, including the pan-resistant T315I mutation. Ponatinib should be used catiously with respect to increased cardiovascular risk. Despite previous TKI failure, chronic-phase CML patients can achieve sustained remissions using this drug, offering an important addition to therapeutic options in the treatment for CML.

Prognostic significance of additional chromosomal abnormalities at the time of diagnosis in patients with chronic myeloid leukemia treated with frontline tyrosine kinase inhibitors

Additional cytogenetic abnormalities (ACA) are considered a high risk feature in chronic myeloid leukemia (CML). However, its prognostic significance at the time of diagnosis in the setting of new tyrosine kinase inhibitors (TKIs) is less well understood. Patients with CML in CP with or without ACA at diagnosis treated with frontline TKIs in prospective clinical trials were analyzed for outcomes. Among 603 patients treated, 29 (5%) had ACA. Patients with ACA included 2 of 72 (2.8%) treated with imatinib 400 mg, 9 of 207 (4.3%) with imatinib 800 mg, 10 of 148 (6.7%) with dasatinib, 6 of 126 (4.7%) with nilotinib, and 2 of 50 (4%) with ponatinib. There was a significantly higher rate of complete cytogenetic response (CCyR) at 6 months in patients without ACA (P = .02). However cumulative CCyR and major molecular response (MMR) rates were not different. Similarly, MR4.0 and MR4.5 rates were similar for both groups; two CML-ACA patients maintained MR 4.5 for at least 2 years. At 5 years, ACA at diagnosis did not significantly impact transformation-free, failure-free, event-free, or overall survival expectations. Acknowledging small sample size estimates, response rates and survival outcomes were comparable in CP with ACA irrespective of whether chromosomal abnormalities were "major route" or other. The presence of ACA at diagnosis does not confer worse prognosis for patients with CML treated with TKI. Thus, the presence of ACA at diagnosis should not alter treatment strategies in these patients.

Chronic Myeloid Leukemia: What Every Practitioner Needs to Know in 2017

The prognosis of chronic phase chronic myeloid leukemia (CML) has improved so that life expectancy for patients responding to tyrosine kinase inhibitors (TKIs) is now equivalent to age-matched controls. Attention should be paid to comorbidities that impact survival. The success of TKI therapy can be easily and reliably assessed at well-accepted time points using quantitative polymerase chain reaction (PCR) standardized to the international scale. Patient-reported outcome (PRO) tools are readily available for use in the clinic and provide complementary information on the tolerance of TKIs. Effectively managing adverse events of TKIs can improve compliance and quality of life. Discontinuation of TKIs is the next frontier in CML. In select patients with sustained deep molecular remission, a discontinuation of TKI is associated with a durable treatment-free remission in approximately 50%. Patient engagement in their discontinuation can be achieved through a provider multi-team coaching, is complementary to the available guidelines, and may provide an additional safety net so that these discontinuations remain safe when applied in general practices.

The Role of Early Molecular Response in the Management of Chronic Phase CML

Purpose of Review

Although tyrosine kinase inhibitors (TKIs) spectacularly improve the disease burden and the overall survival of chronic myeloid leukemia patients, early identification of a subset of poor TKI responders has been recognized as a critical goal to prevent disease progression in these patients. We herein review the past and recent evidence on the impact of early response.

Recent Findings

In the recent years, the achievement of an early molecular response (EMR, defined as 3-month BCR-ABL1 transcript <10% IS) has emerged as a useful tool to identify poor-risk patients. Although several groups have reported the importance of such milestone, clinical intervention based on it remains controversial partly due to its low specificity to predict progression, which may be partially improved by using the rate of decline in BCR-ABL1 transcript level (halving time or velocity of ratio reduction).

Summary

Standardization of halving time or velocity of ratio reduction will likely help establishing more stringent recommendation and modify current clinical practices.

First-line therapy for chronic phase CML: selecting the optimal BCR-ABL1-targeted TKI

Patients diagnosed with chronic myeloid leukemia (CML) and treated with BCR-ABL1 tyrosine kinase inhibitors (TKIs) have long life spans. Selection of an appropriate first-line therapy can be difficult as both the unique characteristics of each TKI and patient need to be taken into account to find the optimal match. Patient characteristics include comorbidities, concomitant medications, lifestyle, risk factors, BCR-ABL1 transcript type (e.g. b2a2 or b3a2) and additional chromosomal abnormalities. Just as patients differ, side effects, drug-drug interactions, administration plans, dosing schedules and treatment-related expenses across TKIs also vary. Alignment of these characteristics with the appropriate TKI is key to successfully initiating CML treatment. Continued success relies on communication between the patient and the healthcare team, adherence and optimization of therapy once it is initiated. In this review, we discuss these factors, in addition to TKI efficacy and safety, the cost of therapy, the future of treating CML and treatment-free remission.

Moderate anemia at diagnosis is an independent prognostic marker of the EUTOS, Sokal, and Hasford scores for survival and treatment response in chronic-phase, chronic myeloid leukemia patients with frontline imatinib

OBJECTIVES

This study aimed to examine the prognostic value of anemia for the diagnosis of chronic myeloid leukemia in the chronic phase (CML-CP) receiving imatinib.

METHODS

One hundred and fifty-four CML-CP patients were enrolled. The influences of moderate anemia with hemoglobin (Hb) < 10 g/dl, four scoring systems, and the early molecular response at 3 months (BCR-ABL ≤10%; 3M-EMR) on the achievement of a deep molecular response (DMR, MR4.5), progression-free survival (PFS), event-free survival (EFS), and overall survival (OS) were compared.

RESULTS

Moderate anemia was identified in 44 (28.6%) patients. These patients had more aggressive baseline features and higher risks, as assessed by scoring systems, and less favorable treatment responses vs those without anemia, including 3M-EMR (50.0% vs 69.1%), a complete cytogenetic response at 6 months (20.5% vs 50.9%), and a major molecular response at 12 months (22.5% vs 45.2%), with a median follow-up of 54.0 months. Furthermore, an Hb of 10 g/dl better distinguished DMR, EFS, PFS, and OS than the EUTOS, Sokal, and Hasford scores, and better predicted the responses and survivals in combination with 3M-EMR than 3M-EMR alone.

CONCLUSIONS

This finding highlights the significance of anemia in CML-CP, and suggests that patients with anemia at diagnosis should be carefully monitored and might benefit from more potent TKIs if not achieving 3M-EMR.

Introduction of second-generation tyrosine kinase inhibitors may reduce the prognostic impact of high-risk patients, according to the European treatment and outcome study (EUTOS) score

Our study aims to highlight the critical role of the introduction of second generation tyrosine kinase inhibitors (2nd TKIs) on the prognosis of patients with chronic myeloid leukemia (CML) in chronic phase (CML-CP), as determined by European Treatment and Outcome Study (EUTOS) system. Patients who were diagnosed with CML-CP before March 2009 were classified into the imatinib group, and those diagnosed after April 2009 were classified into the 2nd TKI group. EUTOS high-risk patients exhibited significantly worse outcomes in terms of event-free survival (EFS), progression-free survival (PFS), and CML-associated death than those considered to be low-risk. Risk stratification by EUTOS score was predictive of risk-associated clinical outcomes in patients classified into the imatinib group; however, the EUTOS score failed to predict the outcomes of patients classified into the 2nd TKI group. Our data suggest that the introduction of 2nd TKIs might have improved treatment outcomes, particularly in EUTOS high-risk patients.

Insights into the management of chronic myeloid leukemia in resource-poor settings: a Mexican perspective

INTRODUCTION

The arrival of targeted therapy for chronic myeloid leukemia (CML) was revolutionary. However, due to the high cost of tyrosine kinase inhibitors, access to this highly effective therapy with strict monitoring strategies is limited in low to middle-income countries. In this context, following standard recommendations proposed by experts in developed countries is difficult. Areas covered: This review aims to provide an insight into the management of patients with CML living in a resource-limited setting. It addresses several issues: diagnosis, initial treatment, disease monitoring, and additional treatment alternatives including allogeneic hematopoietic stem cell transplantation. Expert commentary: Imatinib is probably the most cost-effective TKI for initial treatment in developing and underdeveloped countries. Generic imatinib preparations should be evaluated before considering their widespread use. Adherence to treatment should be emphasized. Adequate monitoring can be performed through several methods successfully and is important for predicting outcomes, particularly early in the first year, and if treatment suspension is being considered. Access to further therapeutic alternatives should define our actions after failure or intolerance to imatinib, preferring additional TKIs if possible. Allogeneic transplantation in chronic phase is a viable option in this context.

PTCH1 is a reliable marker for predicting imatinib response in chronic myeloid leukemia patients in chronic phase

Patched homolog 1 gene (PTCH1) expression and the ratio of PTCH1 to Smoothened (SMO) expression have been proposed as prognostic markers of the response of chronic myeloid leukemia (CML) patients to imatinib. We compared these measurements in a realistic cohort of 101 patients with CML in chronic phase (CP) using a simplified qPCR method, and confirmed the prognostic power of each in a competing risk analysis. Gene expression levels were measured in peripheral blood samples at diagnosis. The PTCH1/SMO ratio did not improve PTCH1 prognostic power (area under the receiver operating characteristic curve 0.71 vs. 0.72). In order to reduce the number of genes to be analyzed, PTCH1 was the selected measurement. High and low PTCH1 expression groups had significantly different cumulative incidences of imatinib failure (IF), which was defined as discontinuation of imatinib due to lack of efficacy (5% vs. 25% at 4 years, P = 0.013), probabilities of achieving a major molecular response (81% vs. 53% at first year, P = 0.02), and proportions of early molecular failure (14% vs. 43%, P = 0.015). Every progression to an advanced phase (n = 3) and CML-related death (n = 2) occurred in the low PTCH1 group (P<0.001 for both comparisons). PTCH1 was an independent prognostic factor for the prediction of IF. We also validated previously published thresholds for PTCH1 expression. Therefore, we confirmed that PTCH1 expression can predict the imatinib response in CML patients in CP by applying a more rigorous statistical analysis. Thus, PTCH1 expression is a promising molecular marker for predicting the imatinib response in CML patients in CP.

BCR-ABL1 tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia

The management of chronic myeloid leukemia with BCR-ABL1 tyrosine kinase inhibitors has evolved chronic myeloid leukemia into a chronic, manageable disease. A patient-centered approach is important for the appropriate management of chronic myeloid leukemia and optimization of long-term treatment outcomes. The pharmacist plays a key role in treatment selection, monitoring drug–drug interactions, identification and management of adverse events, and educating patients on adherence. The combination of tyrosine kinase inhibitors with unique safety profiles and individual patients with unique medical histories can make managing treatment difficult. This review will provide up-to-date information regarding tyrosine kinase inhibitor-based treatment of patients with chronic myeloid leukemia. Management strategies for adverse events and considerations for drug–drug interactions will not only vary among patients but also across tyrosine kinase inhibitors. Drug–drug interactions can be mild to severe. In instances where co-administration of concomitant medications cannot be avoided, it is critical to understand how drug levels are impacted and how subsequent dose modifications ensure therapeutic drug levels are maintained. An important component of patient-centered management of chronic myeloid leukemia also includes educating patients on the significance of early and regular monitoring of therapeutic milestones, emphasizing the importance of adhering to treatment in achieving these targets, and appropriately modifying treatment if these clinical goals are not being met. Overall, staying apprised of current research, utilizing the close pharmacist–patient relationship, and having regular interactions with patients, will help achieve successful long-term treatment of chronic myeloid leukemia in the age of BCR-ABL1 tyrosine kinase inhibitors.

Treatment adherence in chronic myeloid leukaemia patients receiving tyrosine kinase inhibitors

Failure to comply with treatment recommendations is very common in patients, but still poorly recognised by doctors. The current practice of using oral therapy on a large scale has been increasingly adopted for cancer patients. Chronic myeloid leukaemia (CML) is just such an example, where the introduction of taking new oral medications, the tyrosine kinase BCR-ABL inhibitors (TKI), has now revolutionised the treatment. The aim of our study was to assess treatment adherence in a group of Polish CML patients (a survey was conducted on 140 patient aged ≥18 years) treated with oral TKI (imatinib, dasatinib and nilotinib) taking into account the following variables: gender, age, education, place of residence, family circumstances and duration of therapy. In addition, we evaluated whether there is a relationship between how patients perceive their level of adherence to treatment recommendations with how subjectively the required dosage regimen was followed. Half the patients admitted to skipping at least one drug dose during the entire course of treatment and 39% did so within their last treatment month. Patients were also found to overestimate their own adherence assessment; around 60% of those missing at least 1 drug dose within the last treatment month believed they 'always' followed recommendations. The study demonstrated that adherence deteriorates over time. Furthermore, patients aged >65 years and patients suffering at least one comorbid disease had better adherence (p < 0.011). There were no differences in adherence among patients treated with imatinib, dasatinib and nilotinib (p = 0.249).

Molecular response to imatinib mesylate of Brazilian patients with chronic myeloid leukemia

Background

Imatinib mesylate has revolutionized the treatment of chronic myeloid leukemia leading to significant reductions of BCR-ABL1 transcript levels in peripheral blood.

Objective

To evaluate the response to imatinib mesylate treatment (400 mg/day) in Brazilian patients in the chronic phase of chronic myeloid leukemia monitored by quantitative real time polymerase chain reaction.

Methods

Between October 2002 and October 2010, 3169 peripheral blood samples were collected from 1403 patients from 3 to 5 months, 6 to 11 months, 12 to 17 months, 18 to 23 months and ≥24 months after beginning imatinib treatment. Eighty-two patients had samples available and analyzed for all time intervals. BCR-ABL1 quantification was performed by quantitative real time polymerase chain reaction using the ABL1 gene as the control. Results of the BCR-ABL1 ratio as a percentage were reported by the international scale (IS) using the laboratory conversion factor (0.51).

Results

In the first interval, 80.8% of patients achieved the optimal response (BCR-ABL1^IS ≤ 10%). In the second period, 69.1% achieved optimal response (BCR-ABL1^IS ≤ 1%) and, between 12 and 17 months, 47.3% achieved major molecular response (BCR-ABL1^IS ≤ 0.1%).

Conclusions

The results of this retrospective study show that the response to imatinib treatment (400 mg/day) of Brazilian patients in the chronic phase of chronic myeloid leukemia is within the expected profile when compared to patients reported in international prospective randomized studies.

Can the Use of Bone Marrow Parameters Improve the Efficacy of Risk Prediction Scores in Chronic Myeloid Leukemia in Imatinib Era?

INTRODUCTION

Many attempts have been made to develop risk prediction scores for chronic myeloid leukemia in chronic phase (CML-CP) to identify the subgroup with a poorer response to therapy to enable early intensification of treatment. Because the bone marrow (BM) provides a more sensitive reflection of the disease process, we hypothesized that using BM parameters in the Sokal and European Treatment and Outcome Study (EUTOS) risk scores could improve their efficacy in an imatinib-treated population.

MATERIALS AND METHODS

We analyzed cases of CML-CP for their response and survival outcomes with imatinib using risk groupings determined by the Sokal and EUTOS scores using peripheral blood (PB) or BM parameters (Sokal-PB, Sokal-BM, EUTOS-PB, and EUTOS-BM).

RESULTS

A total of 371 cases were analyzed. The concordance for risk groups was greater for the EUTOS scores (81.9%) than for the Sokal scores (68.1%) using PB versus BM parameters. For all 4 risk scores, the predictive efficacy was statistically significant. EUTOS-PB and EUTOS-BM could better prognosticate for progression-free survival (PFS) and overall survival (OS) between the low- and high-risk groups (P < .0001). However, with the Sokal risk score, the use of BM parameters improved the prognostic capacity for PFS between the low- and intermediate-risk groups, with a statistically significant difference (P = .025), but not for OS (P = .88).

CONCLUSION

The use of BM parameters, a simple method that is feasible in routine clinical practice could improve the prognostic efficacy of the Sokal score for PFS but not for OS in low- and intermediate-risk groups. Further research to improve the sensitivity of risk scores for CML-CP prognosis and attempts at risk-directed therapy is warranted.

Treating Philadelphia chromosome/BCR-ABL1 positive patients with Glivec (Imatinib mesylate): 10 years' experience at Patan Hospital, Nepal

The Glivec International Patient Assistance Programme makes Glivec (Imatinib mesylate) available to Philadelphia chromosome/BCR-ABL1 positive patients with chronic myeloid leukaemia (CML) in Lower and Middle Income Countries (LMIC). We have established a large cohort of 211 CML patients who are eligible for Imatinib, in Kathmandu, Nepal. Thirty-one patients were lost to follow-up. We report on 180 CML patients with a median age of 38 years (range 9-81). Of these 180 patients, 162 underwent cytogenetic testing and 110 were investigated by reverse transcription polymerase chain reaction. One hundred and thirty-nine of the 180 patients (77·2%) had at least one optimal response. Taken together, our cohort has a 95% overall survival rate and 78% of the patients were still taking Glivec at a median time of 48·8 months (range 3-140 months). The number of patients who actually failed therapy, as defined by the LeukaemiaNet 2013 criteria, was 39 (21·7%). While our cohort has some differences with those in North America or Europe, we have shown Glivec is effective in inducing an optimal response in our patients in Nepal and that it is possible to deliver a clinical service for CML patients using tyrosine kinase inhibitors in resource-poor settings.

Presence of novel compound BCR-ABL mutations in late chronic and advanced phase imatinib sensitive CML patients indicates their possible role in CML progression

BCR-ABL kinase domain (K_D) mutations are well known for causing resistance against tyrosine kinase inhibitors (TKIs) and disease progression in chronic myeloid leukemia (CML). In recent years, compound BCR-ABL mutations have emerged as a new threat to CML patients by causing higher degrees of resistance involving multiple TKIs, including ponatinib. However, there are limited reports about association of compound BCR-ABL mutations with disease progression in imatinib (IM) sensitive CML patients. Therefore, we investigated presence of ABL-K_D mutations in chronic phase (n = 41), late chronic phase (n = 33) and accelerated phase (n = 16) imatinib responders. Direct sequencing analysis was used for this purpose. Eleven patients (12.22%) in late-CP CML were detected having total 24 types of point mutations, out of which 8 (72.72%) harbored compound mutated sites. SH2 contact site mutations were dominant in our study cohort, with E355G (3.33%) being the most prevalent. Five patients (45%) all having compound mutated sites, progressed to advanced phases of disease during follow up studies. Two novel silent mutations G208G and E292E/E were detected in combination with other mutants, indicating limited tolerance for BCR-ABL1 kinase domain for missense mutations. However, no patient in early CP of disease manifested mutated ABL-K_D. Occurrence of mutations was found associated with elevated platelet count (p = 0.037) and patients of male sex (p = 0.049). The median overall survival and event free survival of CML patients (n = 90) was 6.98 and 5.8 y respectively. The compound missense mutations in BCR-ABL kinase domain responsible to elicit disease progression, drug resistance or disease relapse in CML, can be present in yet Imatinib sensitive patients. Disease progression observed here, emphasizes the need of ABL-K_D mutation screening in late chronic phase CML patients for improved clinical management of disease.

The chronic myeloid leukemia stem cell: stemming the tide of persistence

Chronic myeloid leukemia (CML) is caused by the acquisition of the tyrosine kinase BCR-ABL1 in a hemopoietic stem cell, transforming it into a leukemic stem cell (LSC) that self-renews, proliferates, and differentiates to give rise to a myeloproliferative disease. Although tyrosine kinase inhibitors (TKIs) that target the kinase activity of BCR-ABL1 have transformed CML from a once-fatal disease to a manageable one for the vast majority of patients, only ∼10% of those who present in chronic phase (CP) can discontinue TKI treatment and maintain a therapy-free remission. Strong evidence now shows that CML LSCs are resistant to the effects of TKIs and persist in all patients on long-term therapy, where they may promote acquired TKI resistance, drive relapse or disease progression, and inevitably represent a bottleneck to cure. Since their discovery in patients almost 2 decades ago, CML LSCs have become a well-recognized exemplar of the cancer stem cell and have been characterized extensively, with the aim of developing new curative therapeutic approaches based on LSC eradication. This review summarizes our current understanding of many of the pathways and mechanisms that promote the survival of the CP CML LSCs and how they can be a source of new gene coding mutations that impact in the clinic. We also review recent preclinical approaches that show promise to eradicate the LSC, and future challenges on the path to cure.

A population-based study of chronic myeloid leukemia patients treated with imatinib in first line

Chronic myeloid leukemia (CML) treatment is based on company-sponsored and academic trials testing different tyrosine kinase inhibitors (TKIs) as first-line therapy. These studies included patients selected according to many inclusion-exclusion criteria, particularly age and comorbidities, with specific treatment obligations. In daily clinical practice (real-life), inclusion-exclusion criteria do not exist, and the treatment outcome does not only depend on the choice of first-line TKI but also on second- and third-line TKIs. To investigate in a real-life setting the response and the outcome on first-line imatinib, with switch to second generation TKIs in case of unsatisfying response or intolerance, we analyzed all newly diagnosed patients (N = 236), living in two Italian regions, registered in a prospective study according to population-based criteria and treated front-line with imatinib. A switch from imatinib to second-generation TKIs was reported in 14% of patients for side effects and in 24% for failure or suboptimal response, with an improvement of molecular response in 57% of them. The 5-year overall survival (OS) and leukemia-related survival (LRS) were 85% and 93%, respectively; the 4-year rates of MR^3.0 and MR^4.0 were 75% and 48%, respectively. Cardiovascular complications were reported in 4% of patients treated with imatinib alone and in 6% of patients receiving nilotinib as second-line. Older age (≥70 years) affected OS, but not LRS. These data provide an unbiased reference on the CML management and on the results of TKI treatment in real-life, according to ELN recommendations, using imatinib as first-line treatment and second-generation TKIs as second-line therapy. Am. J. Hematol. 92:82-87, 2017. © 2016 Wiley Periodicals, Inc.

In Vivo Cytochrome P450 3A Isoenzyme Activity and Pharmacokinetics of Imatinib in Relation to Therapeutic Outcome in Patients With Chronic Myeloid Leukemia

BACKGROUND

Cytochrome P450 3A (CYP3A) isoenzyme metabolic activity varies between individuals and is therefore a possible candidate of influence on the therapeutic outcome of the tyrosine kinase inhibitor imatinib in patients with chronic myeloid leukemia (CML). The aim of this study was to investigate the influence of CYP3A metabolic activity on the plasma concentration and outcome of imatinib in patients with CML.

METHODS

Forty-three patients with CML were phenotyped for CYP3A activity using quinine as a probe drug and evaluated for clinical response parameters. Plasma concentrations of imatinib and its main metabolite, CGP74588, were determined using liquid chromatography-mass spectrometry.

RESULTS

Patients with optimal response to imatinib after 12 months of therapy did not differ in CYP3A activity compared to nonoptimal responders (quinine metabolic ratio of 14.69 and 14.70, respectively; P = 0.966). Neither the imatinib plasma concentration nor the CGP74588/imatinib ratio was significantly associated with CYP3A activity.

CONCLUSIONS

The CYP3A activity does not influence imatinib plasma concentrations or the therapeutic outcome. These results indicate that although imatinib is metabolized by CYP3A enzymes, this activity is not the rate-limiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes so as to identify the major contributor to patient variability in imatinib plasma concentrations.

Tyrosine kinase inhibitors in chronic myeloid leukaemia: which, when, for whom?

The therapeutic armamentarium for chronic myeloid leukaemia (CML) comprises mainly tyrosine kinase inhibitors (TKIs), with several agents available for frontline treatment, or for the treatment of disease resistance or intolerance to the first-choice or second-choice drug. The availability of different drugs is a major achievement, but means that choices must be made - which can be difficult and questionable at times. The most important end point considered in decision-making regarding treatment for any cancer is overall survival, but additional factors (such as age, prognostic category, safety, or the possibility of achieving treatment-free remission) should be considered when selecting an agent for frontline treatment. Regardless of the TKI selected for first-line treatment, guidelines that define the importance of reaching specific response indicators and procedures for vigilant follow-up monitoring are established to ensure timely implementation of second-line TKIs. Herein, we discuss the benefits and risks of the different TKIs available for the treatment of patients with CML, and how to decide when to employ these agents at different treatment settings.

Inhibition of Aurora kinases induces apoptosis and autophagy via AURKB/p70S6K/RPL15 axis in human leukemia cells

Leukemia is a common malignancy of blood cells with poor prognosis in many patients. Aurora kinases, a family of serine/threonine kinases, play a key role in regulating cell division and mitosis and are linked to tumorigenesis, metastasis, and poor prognosis in many human cancers including leukemia and lymphoma. Danusertib (Danu) is a pan-inhibitor of Aurora kinases with few data available in leukemia therapy. This study aimed to identify new molecular targets for Aurora kinase inhibition in human leukemia cells using quantitative proteomic analysis followed by verification experiments. There were at least 2932 proteins responding to Danu treatment, including AURKB, p70S6K, and RPL15, and 603 functional proteins and 245 canonical signaling pathways were involved in regulating cell proliferation, metabolism, apoptosis, and autophagy. The proteomic data suggested that Danu-regulated RPL15 signaling might contribute to the cancer cell killing effect. Our verification experiments confirmed that Danu negatively regulated AURKB/p70S6K/RPL15 axis with the involvement of PI3K/Akt/mTOR, AMPK, and p38 MAPK signaling pathways, leading to the induction of apoptosis and autophagy in human leukemia cells. Further studies are warranted to verify the feasibility via targeting AURKB/p70S6K/RPL15 axis for leukemia therapy.

[Compliance to imatinib therapy in patients with chronic myeloid leukemia in Henan province and its influence on cytogenetic response at 12 months]

目的

观察2013年3月1日至2015年3月1日就诊河南省肿瘤医院血液科接受伊马替尼（IM) 400 mg/d治疗的513例慢性髓性白血病慢性期（CML-CP）患者的治疗依从性及其对12个月时细胞遗传学反应的影响。

方法

513例CML-CP患者均来自河南省，其中参加新型农村合作医疗保险456例，其他医疗保险57例。患者接受IM治疗后，对其进行常规患教，告知其定期复查骨髓象、BCR-ABL融合基因及染色体的重要性。每例患者随访12个月，根据其定期复查情况分别将其纳入依从性好组或依从性差组。通过卡方检验比较两组在12个月时的完全细胞遗传学反应（CCyR）率及Sokal评分危险度分布的差异；并记录患者诊断至开始IM治疗时间、受教育程度、个人年收入、居住地至医院的交通是否便利、年龄、性别等，通过Cox单因素及多因素分析影响12个月CCyR的因素。

结果

513例CML-CP患者在IM治疗12个月时依从性好组（354例）CCyR率达82.2%，依从性差组（159例）CCyR率为50.9%，差异有统计学意义（P<0.001）；通过Sokal评分进行危险度分层，依从性好组低、中、高危分别为121、132、101例；依从性差组分别为58、61、40例，两组患者疾病危险度分布的差异无统计学意义（P=0.721）；COX单因素分析示，Sokal评分、年收入、受教育程度、诊断至开始治疗时间、依从性均与12个月时CCyR率显著相关（P值均<0.05）。Cox多因素分析示：受教育程度低（B=0.457，P=0.018）、年收入低（B=0.267，P=0.035）及治疗依从性差（B=0.587，P=0.026）是IM治疗中影响患者12个月时CCyR率的独立危险因素。

结论

依从性好的CML-CP患者接受IM治疗12个月时获得较好的遗传学反应；低学历、低收入及依从性差是影响患者12个月时CCyR率的独立危险因素。

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.

Health-related quality of life during bosutinib (SKI-606) therapy in patients with advanced chronic myeloid leukemia after imatinib failure

OBJECTIVES

The tyrosine kinase inhibitor (TKI) bosutinib has demonstrated activity in patients with advanced phase chronic myeloid leukemia (CML), but effects on health-related quality of life (HRQoL) remain unexplored. This study evaluated HRQoL in advanced CML patients receiving bosutinib in an ongoing phase 2 study following resistance or intolerance to prior imatinib therapy.

METHODS

This analysis included data from 76 accelerated-phase (AP) and 64 blast-phase (BP) patients resistant/intolerant to prior imatinib with or without prior exposure to other TKIs. Patient-reported HRQoL assessments completed at baseline; weeks 4, 8, and 12; every 12 weeks thereafter; and at treatment completion included the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu); general health status was assessed using the 5-item EuroQol (EQ-5D) instrument and a visual analog scale (VAS).

RESULTS

HRQoL at baseline was somewhat worse in BP versus AP CML patients. There was a significant improvement in the mean FACT-Leu Total scale at weeks 24, 36, and 48 in AP CML patients and at weeks 4, 8, 12, 24, 36, 48, and 96 in BP CML patients compared with baseline. EQ-5D Utility scores were stable throughout treatment in AP CML patients but significantly improved versus baseline in BP CML patients at weeks 4, 8, 12, and 36. Mean VAS scores were significantly improved at weeks 8, 36, and 48 in AP CML patients and at weeks 4, 8, 12, 24, 36, and 96 in BP CML patients. The lack of a comparison group limits attribution of improvements in HRQoL specifically to bosutinib treatment; potential bias due to non-ignorable dropout may limit the ability to generalize these findings to situations where durations of therapy exceed the 96-week follow-up duration of the present study.

CONCLUSION

These findings suggest that bosutinib therapy is associated with improved HRQoL in advanced phase CML patients.

CLINICAL TRIAL REGISTRATION

NCT00261846.

'Real-life' study of imatinib therapy in chronic phase-chronic myeloid leukemia: A novel retrospective observational longitudinal analysis

OBJECTIVES

Imatinib is a cornerstone of treatment of chronic myeloid leukemia. It remains unclear whether transient treatment discontinuation or dose changes affect outcome and this approach has not yet been approved for use outside clinical trials.

METHODS

We conducted a retrospective single-institution observational study to evaluate factors affecting response in 'real-life' clinical practice in 138 chronic myeloid leukemia patients in chronic phase treated with imatinib. We used a novel longitudinal data analytical model, with a generalized estimating equation model, to study BCR-ABL variation according to continuous standard dose, change in dose or discontinuation; BCR-ABL transcript levels were recorded. Treatment history was subdivided into time periods for which treatment was given at constant dosage (total 483 time periods). Molecular and cytogenetic complete response was observed after 154 (32%) and 358 (74%) time periods, respectively.

RESULTS

After adjusting for length of time period, no association between dose and cytogenetic complete response rate was observed. There was a significantly lower molecular complete response rate after time periods at a high imatinib dosage.

DISCUSSION

This statistical approach can identify individual patient variation in longitudinal data collected over time and suggests that changes in dose or discontinuation of therapy could be considered in patients with appropriate biological characteristics.

Chronic myeloid leukemia: reminiscences and dreams

With the deaths of Janet Rowley and John Goldman in December 2013, the world lost two pioneers in the field of chronic myeloid leukemia. In 1973, Janet Rowley, unraveled the cytogenetic anatomy of the Philadelphia chromosome, which subsequently led to the identification of the BCR-ABL1 fusion gene and its principal pathogenetic role in the development of chronic myeloid leukemia. This work was also of major importance to support the idea that cytogenetic changes were drivers of leukemogenesis. John Goldman originally made seminal contributions to the use of autologous and allogeneic stem cell transplantation from the late 1970s onwards. Then, in collaboration with Brian Druker, he led efforts to develop ABL1 tyrosine kinase inhibitors for the treatment of patients with chronic myeloid leukemia in the late 1990s. He also led the global efforts to develop and harmonize methodology for molecular monitoring, and was an indefatigable organizer of international conferences. These conferences brought together clinicians and scientists, and accelerated the adoption of new therapies. The abundance of praise, tributes and testimonies expressed by many serve to illustrate the indelible impressions these two passionate and affable scholars made on so many people's lives. This tribute provides an outline of the remarkable story of chronic myeloid leukemia, and in writing it, it is clear that the historical triumph of biomedical science over this leukemia cannot be considered without appreciating the work of both Janet Rowley and John Goldman.

Disarming an Electrophilic Warhead: Retaining Potency in Tyrosine Kinase Inhibitor (TKI)-Resistant CML Lines While Circumventing Pharmacokinetic Liabilities

Pharmacologic blockade of the activation of signal transducer and activator of transcription 3 (STAT3) in tyrosine kinase inhibitor (TKI)-resistant chronic myeloid leukemia (CML) cell lines characterized by kinase-independent resistance was shown to re-sensitize CML cells to TKI therapy, suggesting that STAT3 inhibitors in combination with TKIs are an effective combinatorial therapeutic for the treatment of CML. Benzoic acid- and hydroxamic acid-based STAT3 inhibitors SH-4-054 and SH-5-007, developed previously in our laboratory, demonstrated promising activity against these resistant CML cell lines. However, pharmacokinetic studies in murine models (CD-1 mice) revealed that both SH-4-054 and SH-5-007 are susceptible to glutathione conjugation at the para position of the pentafluorophenyl group via nucleophilic aromatic substitution (SN Ar). To determine whether the electrophilicity of the pentafluorophenyl sulfonamide could be tempered, an in-depth structure-activity relationship (SAR) study of the SH-4-054 scaffold was conducted. These studies revealed that AM-1-124, possessing a 2,3,5,6-tetrafluorophenylsulfonamide group, retained STAT3 protein affinity (Ki =15 μm), as well as selectivity over STAT1 (Ki >250 μm). Moreover, in both hepatocytes and in in vivo pharmacokinetic studies (CD-1 mice), AM-1-124 was found to be dramatically more stable than SH-4-054 (t1/2 =1.42 h cf. 10 min, respectively). AM-1-124 is a promising STAT3-targeting inhibitor with demonstrated bioavailability, suitable for evaluation in preclinical cancer models.

Molecular response to imatinib & its correlation with mRNA expression levels of imatinib influx & efflux transporters in patients with chronic myeloid leukaemia in chronic phase

Background & objectives:

Imatinib is the standard first-line treatment for chronic myeloid leukaemia (CML) patients. About 20 to 30 per cent patients develop resistance to imatinib and fail imatinib treatment. One of the mechanisms proposed is varying expression levels of the drug transporters. This study was aimed to determine the expression levels of imatinib transporter genes (OCT1, ABCB1, ABCG2) in CML patients and to correlate these levels with molecular response.

Methods:

Sixty three CML chronic phase patients who were on 400 mg/day imatinib for more than two years were considered for gene expression analysis study for OCT1, ABCB1 and ABCG2 genes. These were divided into responders and non-responders. The relative transcript expression levels of the three genes were compared between these two categories. The association between the expression values of these three genes was also determined.

Results:

No significant difference in the expression levels of OCT1, ABCB1 and ABCG2 was found between the two categories. The median transcript expression levels of OCT1, ABCB1 and ABCG2 genes in responders were 26.54, 10.78 and 0.64 versus 33.48, 7.09 and 0.53 in non-responders, respectively. A positive association was observed between the expression of the ABCB1 and ABCG2 transporter genes (r=0.407, P<0.05) while no association was observed between the expression of either of the ABC transporter genes with the OCT1 gene.

Interpretation & conclusions:

Our findings demonstrated that the mRNA expression levels of imatinib transporter genes were not correlated with molecular response in CML patients. Further studies need to be done on a large sample of CML patients to confirm these findings.

Osthole shows the potential to overcome P-glycoprotein‑mediated multidrug resistance in human myelogenous leukemia K562/ADM cells by inhibiting the PI3K/Akt signaling pathway

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) has been reported to play a pivotal role in tumor chemotherapy failure. Study after study has illustrated that the phosphoinositide 3-kinase (PI3K)/Akt signaling cascade is involved in the MDR phenotype and is correlated with P-gp expression in many human malignancies. In the present study, osthole, an O-methylated coumarin, exhibited potent reversal capability of MDR in myelogenous leukemia K562/ADM cells. Simultaneously, the uptake and efflux of Rhodamine-123 (Rh-123) and the accumulation of doxorubicin assays combined with flow cytometric analysis suggested that osthole could increase intracellular drug accumulation. Furthermore, osthole decreased the expression of multidrug resistance gene 1 (MDR1) at both the mRNA and protein levels. Further experiments elucidated that osthole could suppress P-gp expression by inhibiting the PI3K/Akt signaling pathway which might be the main mechanism accounting for the reversal potential of osthole in the MDR in K562/ADM cells. In conclusion, osthole combats MDR and could be a promising candidate for the development of novel MDR reversal modulators.