Suboptimal responses in chronic myeloid leukemia: implications and management strategies

Chronic myeloid leukaemia patients at diagnosis and resistant to tyrosine kinase inhibitor therapy display exhausted T-cell phenotype

The search for novel targets in chronic myeloid leukaemia (CML) is ongoing, to improve treatment efficacy in refractory disease and increase eligibility for tyrosine kinase inhibitor (TKI) discontinuation. Increased frequency of Tregs and effector Tregs was evident at diagnosis, together with increased expression of T‐cell exhaustion markers, including in regulatory T cells at diagnosis and in patients with refractory disease. Plasma analysis revealed significantly increased levels of cytokines including tumour necrosis factor (TNF)‐a and interleukin (IL)‐6 at diagnosis, in keeping with a pro‐inflammatory state prior to treatment. We hence demonstrate T‐cell exhaustion and a pro‐inflammatory state at diagnosis in CML, likely secondary to leukaemia‐associated antigenic overload associated with increased disease burden.

Plasma imatinib levels and ABCB1 polymorphism influences early molecular response and failure-free survival in newly diagnosed chronic phase CML patients

Achieving early molecular response (EMR) has been shown to be associated with better event free survival in patients with chronic phase chronic myeloid leukemia (CP-CML) on Imatinib therapy. We prospectively evaluated the factors influencing the 2-year failure free survival (FFS) and EMR to imatinib therapy in these patients including day29 plasma Imatinib levels, genetic variants and the gene expression of target genes in imatinib transport and biotransformation. Patients with low and intermediate Sokal score had better 2-year FFS compared to those with high Sokal Score (p = 0.02). Patients carrying ABCB1-C1236T variants had high day29 plasma imatinib levels (P = 0.005), increased EMR at 3 months (P = 0.044) and a better 2 year FFS (P = 0.003) when compared to those with wild type genotype. This translates to patients with lower ABCB1 mRNA expression having a significantly higher intracellular imatinib levels (P = 0.029). Higher day29 plasma imatinib levels was found to be strongly associated with patients achieving EMR at 3 months (P = 0.022), MMR at 12 months (P = 0.041) which essentially resulted in better 2-year FFS (p = 0.05). Also, patients who achieved EMR at 3 months, 6 months and MMR at 12 months had better FFS when compared to those who did not. This study suggests the incorporation of these variables in to the imatinib dosing algorithm as predictive biomarkers of response to Imatinib therapy.

A Single Center Study of Prescribing and Treatment Outcomes of Patients with Chronic Myeloid Leukemia

Background: The present study investigated the patients with Chronic Myeloid Leukemia in chronic phase (CP-CML) who had been on the first- line Imatinib Mesylate (IM) therapy for a period of 84 months. Materials and Methods: This retrospective study was conducted in 295 newly-diagnosed CP-CML patients(age >18 years) who were admitted to the Hematology, Oncology and Stem Cell Transplantation Research Center, Shariati Hospital, Tehran during 1 January, 2009 to 30 December, 2016. Response to treatment was evaluated by molecular response assessment. Rates of IM dose adjustment, switching to another drug therapy, progression to Accelerate Phase (AP) and Blastic Crisis (BC) and long-term outcomes included Overall Survival (OS) and Progression Free Survival (PFS) were assesed. Results: Patients' average age was 41.7 years, and 52.9% were male. 44.4% of patients at the month 18 achieved Major Molecular Response (MMR). Progression to AP/BC occurred in 26 patients during 84 months, and the estimated rate of OS and PFS were 71.83 and 74.48, respectively. Among the patients who did not achieve MMR at month 18 , 61 patients were treated with IM ( 400 mg /day), and then after month 18, 24(39.3%) of whom achieved MMR. Dose adjustments occurred in 60 patients (20.33%). IM dose increase was observed in 53 patients who did not achive optimal response to imatinib or loss of optimal response. IM dose decrease was observed in 7 patients. 25 (8.47%) patients were switched to a different Tyrosine Kinase Inhibitor (TKI). Most of TKI changes(n=21) happened in patients who did not achieve optimal response to IM and TKI changes owing to adverse events of IM were observed in 4 patients.. Among the patients undergoing change in treatment, 24(43.75%) patients achieved MMR. Conclusion: Our data showed the high effectiveness of the change in the treatment of IM-resistant condition. Moreover, our finding suggests that imatinib be effective in Iranian patients after a long period of time compared to the referenced studies.

Evaluation of Molecular Response to Imatinib Mesylate Treatment in Iranian Patients With Chronic Myeloid Leukemia

BACKGROUND

Imatinib mesylate has revolutionized the treatment of patients with chronic myeloid leukaemia (CML); however, some patients fail to respond and have a poor prognosis. Evaluation of molecular response to imatinib is a sensitive method can help physicians make better and quicker therapeutic decisions in the course of this disease. This study aims to evaluate the molecular response to generic imatinib in Iranian patients with CML.

PATIENTS AND METHODS

This prospective study consisted of 255 newly diagnosed patients with CML who received imatinib. Molecular response was analyzed at 3 and 6 months from the start of the treatment and then every 6 months, and long-term outcomes, including overall survival (OS) and progression-free survival (PFS), were evaluated.

RESULTS

At a median follow-up of 34.8 months (range, 3-84 months, (the OS and PFS at 7 years were 94.3% and 92.9%, respectively. Eighty-four-month PFS rates in patients with a BCR-ABLIS ≤ 10% at 3 months and BCR-ABLIS ≤ 1% at 6 months were significantly higher than patients who did not obtain these levels of BCR-ABL transcripts (P = .004 and P < .0001, respectively). The proportion of patients who achieved major molecular response (MMR) was 44.1%, 52.97%, and 60.75% at 12, 18, and 24 months, respectively. At 12, 18, and 84 months, the PFS rates in patients who achieved MMR were significantly higher than in patients who did not achieve MMR (P = .002, P < .0001, and P = .003, respectively).

CONCLUSIONS

The data of this prospective study are highly comparable with that from clinical trials and prospective international studies.

Comparative analyses of nilotinib versus high-dose imatinib versus sustained standard-dose imatinib in patients with chronic phase chronic myeloid leukemia following suboptimal molecular response to first-line imatinib

The aim of this study was to investigate the efficacy of nilotinib (NIL) versus high-dose imatinib (IM) versus sustained standard-dose IM for patients with chronic myeloid leukemia (CML) with suboptimal molecular response to first-line IM therapy. Patients with CML who achieved complete cytogenetic response (CCyR) but not major molecular response (MMR) after 18-24 months on first-line IM therapy were enrolled and divided into three treatment cohorts: NIL 800 mg/day (Cohort 1, n = 28) and IM 800 mg/day (Cohort 2, n = 28) in the RE-NICE study, and sustained IM 400 mg/day (Cohort 3, n = 52) in clinical practice. The primary efficacy variable of cumulative rate of MMR by 12 months was not different among the three cohorts. However, the cumulative incidence of MMR by 36 months was significantly higher in Cohort 1 than Cohort 3 (83.1% vs. 57.1%, P = 0.021), but there were no significant differences in Cohort 1 vs. 2 (P = 0.195) and Cohort 2 vs. 3 (P = 0.297). Different profile for adverse events was observed between NIL and high-dose IM therapy. In conclusion, our data suggested that switching to NIL may provide more effective long-term response than sustaining standard-dose IM for patients with suboptimal molecular response to first-line IM.

BCR-ABL V280G Mutation, Potential Role in Imatinib Resistance: First Case Report

INTRODUCTION

The identification of BCR-ABL expression as the defining leukemogenic event in chronic myeloid leukemia (CML) and the introduction of BCR-ABL tyrosine kinase inhibitors in 2001 have revolutionized disease management, leading to a reduction in mortality rates and accordingly an increase in the estimated prevalence of CML.

CASE REPORT

Based on medical records and clinical follow-up, the authors present the case of a Philadelphia chromosome-positive CML patient who developed resistance to imatinib. Quantitative reverse transcription-polymerase chain reaction testing revealed a V280G BCR-ABL mutation.

DISCUSSION AND CONCLUSIONS

This is the first report describing a new BCR-ABL kinase domain mutation-V280G-that might be associated with resistance to imatinib. Approximately 15% to 30% of patients treated with imatinib discontinue treatment due to resistance or intolerance. More than 90 BCR-ABL mutations were detected so far, conferring variable degrees of drug resistance, with consequent clinical, therapeutic, and prognostic impact.

Increased peroxisome proliferator-activated receptor γ activity reduces imatinib uptake and efficacy in chronic myeloid leukemia mononuclear cells

Imatinib is actively transported by organic cation transporter-1 (OCT-1) influx transporter, and low OCT-1 activity in diagnostic chronic myeloid leukemia blood mononuclear cells is significantly associated with poor molecular response to imatinib. Herein we report that, in diagnostic chronic myeloid leukemia mononuclear cells and BCR-ABL1⁺ cell lines, peroxisome proliferator-activated receptor γ agonists (GW1929, rosiglitazone, pioglitazone) significantly decrease OCT-1 activity; conversely, peroxisome proliferator-activated receptor γ antagonists (GW9662, T0070907) increase OCT-1 activity. Importantly, these effects can lead to corresponding changes in sensitivity to BCR-ABL kinase inhibition. Results were confirmed in peroxisome proliferator-activated receptor γ-transduced K562 cells. Furthermore, we identified a strong negative correlation between OCT-1 activity and peroxisome proliferator-activated receptor γ transcriptional activity in diagnostic chronic myeloid leukemia patients (n=84; P<0.0001), suggesting that peroxisome proliferator-activated receptor γ activation has a negative impact on the intracellular uptake of imatinib and consequent BCR-ABL kinase inhibition. The inter-patient variability of peroxisome proliferator-activated receptor γ activation likely accounts for the heterogeneity observed in patient OCT-1 activity at diagnosis. Recently, the peroxisome proliferator-activated receptor γ agonist pioglitazone was reported to act synergistically with imatinib, targeting the residual chronic myeloid leukemia stem cell pool. Our findings suggest that peroxisome proliferator-activated receptor γ ligands have differential effects on circulating mononuclear cells compared to stem cells. Since the effect of peroxisome proliferator-activated receptor γ activation on imatinib uptake in mononuclear cells may counteract the clinical benefit of this activation in stem cells, caution should be applied when combining these therapies, especially in patients with high peroxisome proliferator-activated receptor γ transcriptional activity.

Analysis of 2013 European LeukaemiaNet (ELN) responses in chronic phase CML across four frontline TKI modalities and impact on clinical outcomes

This study assessed the relevance of 2013 European LeukaemiaNet (ELN) response categories on patients treated with common frontline tyrosine kinase inhibitors (TKI) in chronic myeloid leukaemia in chronic phase (CML-CP). Four hundred and eighty-seven patients treated with imatinib (400 mg; IM 400, n = 70; 800 mg; IM800, n = 201), dasatinib (n = 107) or nilotinib (n = 109) were analysed. Intention to treat (ITT) analysis indicated that the proportion of patients falling into optimal, warning and failure ELN categories were 89%, 6%, 6% at 3 months, 78%, 17% and 6% at 6 months, and 75%, 13% and 13% at 12 months, respectively. Rates of optimal response at 3 months were 75% for IM400, 90% for IM800, 89% for dasatinib and 97% for nilotinib; 41%, 80%, 86% and 89% at 6 months; and 47%, 77%, 76% and 87% at 12 months, respectively. Patients achieving optimal response had longer eventfree (EFS), failurefree (FFS), transformationfree (TFS) and overall survival (OS) compared to warning and failure responses at all-time points. Treatment with imatinib 800, dasatinib or nilotinib predicted for achieving an optimal response. Optimal response predicted for significantly longer EFS, FFS, TFS and OS at 3, 6 and 12 months, irrespective of the TKI modality used. ELN response categories reliably predicted outcomes in CML patients receiving commonly used TKIs.

Interventions for adherence with oral chemotherapy in hematological malignancies: A systematic review

BACKGROUND

Poor adherence to treatment for chronic diseases including some hematological malignancies impedes health outcomes and increases costs. Oral chemotherapy is an emerging trend that raises concern about nonadherence problems in these targeted patients.

OBJECTIVES

This systematic literature review explores evidence and gaps in the literature regarding interventions to enhance adherence with prescribed oral chemotherapy in patients with hematological malignancies.

METHODS

Searches of databases and abstracts from conferences were performed for 1987 to January 2013 using a modified Cochrane method. Studies measuring interventions to improve adherence alone or together with clinical, humanistic, and economic outcomes were included. Assessment of methodological quality was performed for each retained study.

RESULTS

The literature search generated 6 studies that met inclusion criteria. Four of these reported a statistically significant increase in the adherence outcome, compared with baseline. Tailored and educational interventions were widely used among the retained studies. Post-intervention adherence rates were 41-96.1%; intervention groups yielded higher rates than comparison groups. Two studies reported statistically significant improvement in clinical outcomes (cytogenetic response and survival time). One study reported that severity of illness was associated with survival time but not with adherence. Studies that used both tailored and educational interventions showed significant relationship between adherence and clinical outcomes; however, the study that used dosage simplification did not. None of the studies explored humanistic or economic outcomes.

CONCLUSIONS

Interventions to improve adherence with oral chemotherapies in hematological malignancies remain limited. Though they were heterogeneous in nature, interventions tested in the retained studies suggested a positive impact on the adherence outcome; some established a significant relationship between adherence and clinical outcomes. The results yielded limited evidences regarding characteristics of a specific intervention, but supported a general structure for methods to improve adherence and other outcomes in real-life settings. Further rigorous methodological studies are needed to fully examine impact on adherence and clinical outcomes.

Importance of early and deeper responses to long-term survival in CML patients: Implications of BCR-ABL testing in management of CML in Indian setting

The prognosis of patients with chronic myeloid leukemia (CML) has changed radically since the advent of imatinib mesylate, a selective inhibitor of BCR-ABL tyrosine kinase. Shortly thereafter, more potent BCR-ABL inhibitors (dasatinib and nilotinib) were introduced for use in patients resistant to or intolerant of imatinib. All three drugs are now approved for initial therapy for chronic phase CML. Response to tyrosine kinase inhibitor (TKI) treatment is assessed with standardized quantitative reverse transcriptase polymerase chain reaction (Q-RTPCR) and/or cytogenetics at 3, 6 and 12 months. Clinical trials have clearly demonstrated that early and deeper cytogenetic and molecular response to TKI therapy is associated with lower rate of disease progression and improved long-term outcomes. In recent times, molecular response as determined by BCR-ABL transcript levels at defined time points is rapidly gaining popularity as a predictive marker for subsequent outcomes in CML. Optimal response is defined as BCR-ABL transcript levels of ≤10% at 3 months, <1% at 6 months, and ≤0.1% from 12 months onward while >10% at 6 months and >1% from 12 months onward define failure. Patients who do not achieve molecular milestones at 3 or 6 months with 3 months being highly predictive are less likely to achieve cytogenetic responses eventually; early identification of such patients who have a low probability of achieving an adequate response are thus candidates for alternative treatment. Review of literature by electronic search of MEDline, Google Scholar was done using keywords and data was identified and systematically evaluated.

Quality of life of chronic myeloid leukemia patients in Brazil: ability to work as a key factor

PURPOSE

The purpose of this study was to evaluate the quality of life (QOL) of patients receiving treatment by the public health system in Brazil for chronic myeloid leukemia (CML), a disease requiring daily and strict compliance to oral medication and regular blood and bone marrow controls, which are invasive exams.

METHODS

Between 2008 and 2010, patients with CML were surveyed by telephone. Quality of life was evaluated by the functional assessment of chronic illness therapy (FACIT) tool.

RESULTS

The mean QOL among CML patients was 92.53 (out of 124 total points) in the trial outcome index, 78.50 (out of 108) in the general total score, and 130.43 (out of 176) in the leukemia total score. Patients who had the prescriptions recently changed anyway had better QOL general score (p = 0.012) and leukemia-specific score (p = 0.043) than those who remained with the same treatment. Imatinib was not associated with this change in QOL (p > 0.797). The more the patient felt able to work, the higher the scores in all three FACIT scales (p < 0.001, Spearman's correlation). The use of imatinib (p = 0.012) was associated with a better ability to work, while chemotherapy (p = 0.017) and the use of hydroxyurea (p = 0.001) were inversely associated with work capability.

CONCLUSIONS

A recent change in medication can improve quality of life. The ability to work is an important component of quality of life of patients with CML. Ability to work should be specifically considered in CML treatment.

Safety and efficacy of switching to nilotinib 400 mg twice daily for patients with chronic myeloid leukemia in chronic phase with suboptimal response or failure on front-line imatinib or nilotinib 300 mg twice daily

In a randomized, phase III trial of nilotinib versus imatinib in patients with newly diagnosed Philadelphia chromosome positive chronic myeloid leukemia in chronic phase, more patients had suboptimal response or treatment failure on front-line imatinib than on nilotinib. Patients with suboptimal response/treatment failure on imatinib 400 mg once or twice daily or nilotinib 300 mg twice daily could enter an extension study to receive nilotinib 400 mg twice daily. After a 19-month median follow up, the safety profile of nilotinib 400 mg twice daily in patients switching from imatinib (n=35) was consistent with previous reports, and few new adverse events occurred in patients escalating from nilotinib 300 mg twice daily (n=19). Of patients previously treated with imatinib or nilotinib 300 mg twice daily, respectively, 15 of 26 (58%) and 2 of 6 (33%) without complete cytogenetic response at extension study entry, and 11 of 34 (32%) and 7 of 18 (39%) without major molecular response at extension study entry, achieved these responses at any time on nilotinib 400 mg twice daily. Estimated 18-month rates of freedom from progression and overall survival after entering the extension study were lower for patients switched from imatinib (85% and 87%, respectively) versus nilotinib 300 mg twice daily (95% and 94%, respectively). Nilotinib dose escalation was generally well tolerated and improved responses in about one-third of patients with suboptimal response/treatment failure. Switch to nilotinib improved responses in some patients with suboptimal response/treatment failure on imatinib, but many did not achieve complete cytogenetic response (clinicaltrials.gov identifiers: 00718263, 00471497 - extension).

Kinase-inhibitor-insensitive cancer stem cells in chronic myeloid leukemia

INTRODUCTION

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the translocation t(9;22), coding for the chimeric protein BCR-ABL. The development of BCR-ABL tyrosine kinase inhibitors (TKIs) has dramatically revolutionized and improved CML therapy. However, TKI-based therapy faces a major challenge: the insensitivity of CML leukemic stem cells (LSCs) to TKIs. In particular, while CML progenitor cells and differentiated cells are oncogene addicted, BCR-ABL tyrosine kinase is dispensable for CML LSC survival and maintenance. Notably, in CML, additional cellular mechanisms promote LSC survival and maintenance, rendering these cells able to survive even in the presence of TKI and to eventually promote relapse.

AREAS COVERED

This review will focus on the mechanisms of LSC insensitivity to TKI and on the strategies to obtain synthetic lethality with combination therapies.

EXPERT OPINION

Several pathways have been proposed to promote LSC maintenance and described as ideal targets to induce CML LSC exhaustion in combination with TKI. Ongoing clinical trials designed to target some of these pathways will assess which molecular target is relevant for in vivo human LSC survival in a new 'stem-cell targeting' perspective.

[Current diagnostic requirements in chronic myeloid leukemia]

In patients with chronic myeloid leukemia, high-quality diagnostics is of paramount importance for the surveillance of treatment efficacy. The availability of new tyrosine kinase inhibitors providing more rapid and deeper responses requires the employment of standardized and highly sensitive diagnostic methods to ensure optimal monitoring of the patients. This review presents the current international diagnostic standards and the certified laboratories in Austria.

Genomic instability may originate from imatinib-refractory chronic myeloid leukemia stem cells

Genomic instability is a hallmark of chronic myeloid leukemia in chronic phase (CML-CP) resulting in BCR-ABL1 mutations encoding resistance to tyrosine kinase inhibitors (TKIs) and/or additional chromosomal aberrations leading to disease relapse and/or malignant progression. TKI-naive and TKI-treated leukemia stem cells (LSCs) and leukemia progenitor cells (LPCs) accumulate high levels of reactive oxygen species (ROS) and oxidative DNA damage. To determine the role of TKI-refractory LSCs in genomic instability, we used a murine model of CML-CP where ROS-induced oxidative DNA damage was elevated in LSCs, including quiescent LSCs, but not in LPCs. ROS-induced oxidative DNA damage in LSCs caused clinically relevant genomic instability in CML-CP-like mice, such as TKI-resistant BCR-ABL1 mutations (E255K, T315I, H396P), deletions in Ikzf1 and Trp53, and additions in Zfp423 and Idh1. Despite inhibition of BCR-ABL1 kinase, imatinib did not downregulate ROS and oxidative DNA damage in TKI-refractory LSCs to the levels detected in normal cells, and CML-CP-like mice treated with imatinib continued to accumulate clinically relevant genetic aberrations. Inhibition of class I p21-activated protein kinases by IPA3 downregulated ROS in TKI-naive and TKI-treated LSCs. Altogether, we postulate that genomic instability may originate in the most primitive TKI-refractory LSCs in TKI-naive and TKI-treated patients.

Second-generation TKIs: which and when?

Impressive response rates and good tolerability have led imatinib 400 mg once a day to become the standard frontline therapy for chronic myeloid leukemia (CML) patients. However, approximately one-third of the treated patients do not respond in an optimal manner to this drug, and the appropriate type and rhythm of CML monitoring, as well as the correct action to be undertaken in case of failure or suboptimal responses to imatinib therapy have been published in specific recommendations by European Leukemia Net and National Comprehensive Cancer Network. Failure and also cytogenetic suboptimal responses strongly demand for a change in treatment and for a switch from imatinib to one of the two second-generation tyrosine kinase inhibitors (TKIs) so far registered, dasatinib and nilotinib, for which efficacy as second-line therapy in imatinib-resistant or intolerant cases has been clearly demonstrated in phase II studies, and for which 4-year updates are now available. Other TKIs, at the moment, still under clinical investigation for imatinib-resistant patients include bosutinib and the next-generation TKI ponatinib. Different efficacy and safety criteria characterize each of the mentioned compounds and may help to decide on the one to be preferably used in individual patients.

Definitions, methodological and statistical issues for phase 3 clinical trials in chronic myeloid leukemia: a proposal by the European LeukemiaNet

The treatment policy of chronic myeloid leukemia (CML), particularly with tyrosine kinase inhibitors, has been influenced by several recent studies that were well designed and rapidly performed, but their interpretation is of some concern because different end points and methodologies were used. To understand and compare the results of the previous and future studies and to translate their conclusion into clinical practice, there is a need for common definitions and methods for analyses of CML studies. A panel of experts was appointed by the European LeukemiaNet with the aim of developing a set of definitions and recommendations to be used in design, analyses, and reporting of phase 3 clinical trials in this disease. This paper summarizes the consensus of the panel on events and major end points of interest in CML. It also focuses on specific issues concerning the intention-to-treat principle and longitudinal data analyses in the context of long-term follow-up. The panel proposes that future clinical trials follow these recommendations.