Treatment-free remission in CML: who, how, and why?

Prognostic Role of Human Leukocyte Antigen Alleles and Cytokine Single-Nucleotide Polymorphisms in Patients with Chronic Myeloid Leukemia Treated with Tyrosine Kinase Inhibitor Drugs

Tyrosine kinase inhibitor (TKI) drugs have significantly improved chronic myeloid leukemia (CML) outcomes. Neopeptides from CML cells may induce specific immune responses, which are crucial for deep molecular (DMR) and treatment-free remission (TFR). In this study of Ethiopian patients with CML (n = 162), the HLA alleles and single-nucleotide polymorphisms of five cytokines revealed significant associations with clinical outcomes. Clinically unfavorable outcomes correlated with HLA alleles A*03:01/02, A*23:17:01, B*57:01/02/03, and HLA-DRB4*01:01 (p-value = 0.0347, p-value = 0.0285, p-value = 0.037, and p-value = 0.0127, respectively), while HLA-DRB4*01:03:01 was associated with favorable outcomes (p-value = 0.0058). After assigning values for the 'low', 'intermediate', and 'high' gene expression of the SNPs' respective cytokine genes, Kaplan-Meier estimates for relapse-free survival, adjusted for age, treatment duration, and relapse risk among patients after the administration of TKIs, indicated that a gene expression ratio above the overall median of TNF-α, IL-6, and the combination of TGF-β1/IL-10, IFNγ, and IL-6/IL-10 TGF-β1 was correlated with a higher likelihood of treatment failure ((RR: 3.01; 95% CI: 1.1-8.3; p-value = 0.0261) and (RR: 2.4; 95% CI: 1.1-5.2; p-value = 0.022), respectively). Multi-SNPs, surpassing single-SNPs, and HLA allele polymorphisms showed promise in predicting outcomes of patients with CML during TKI treatment, prompting further exploration into their potential utility.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial for investigating the cessation of tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in stable deep molecular remission (DMR). Among 728 patients, 434 patients (61%; 95% CI, 57 to 64) remained in major molecular response (MMR) at 6 months and 309 patients of 678 (46%; 95% CI, 42 to 49) at 36 months. Duration of TKI treatment and DMR before TKI stop were confirmed as significant factors for the prediction of MMR loss at 6 months. In addition, the type of BCR::ABL1 transcript was identified as a prognostic factor. For late MMR losses after 6 months, TKI treatment duration, percentage of blasts in peripheral blood, and platelet count at diagnosis were significant factors in multivariate analysis. For the entire study period of 36 months, multiple logistic regression models confirmed duration of treatment, blasts, and transcript type as independent factors for MMR maintenance. In addition to the duration of treatment, transcript type as well as blasts in peripheral blood at diagnosis should be considered as important factors to predict treatment-free remission.

Advancements and Future Prospects in Molecular Targeted and siRNA Therapies for Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is an oncological myeloproliferative disorder that accounts for 15 to 20% of all adult leukemia cases. The molecular basis of this disease lies in the formation of a chimeric oncogene BCR-ABL1. The protein product of this gene, p210 BCR-ABL1, exhibits abnormally high constitutive tyrosine kinase activity. Over recent decades, several targeted tyrosine kinase inhibitors (TKIs) directed against BCR-ABL1 have been developed and introduced into clinical practice. These inhibitors suppress BCR-ABL1 activity through various mechanisms. Furthermore, the advent of RNA interference technology has enabled the highly specific inhibition of BCR-ABL1 transcript expression using small interfering RNA (siRNA). This experimental evidence opens avenues for the development of a novel therapeutic strategy for CML, termed siRNA therapy. The review delves into molecular genetic mechanisms underlying the pathogenesis of CML, challenges in CML therapy, potential molecular targets for drug development, and the latest results from the application of siRNAs in in vitro and in vivo CML models.

A Retrospective Analysis of BCR-ABL1 Kinase Domain Mutations in the Frontline Drug Intolerant or Resistant Chronic Myeloid Leukemia Patients: An Indian Experience from a High-End Referral Laboratory

Atreye MajumdarSambit K. MohantyObjective  This article identifies and evaluates the frequency of mutations in the BCR-ABL1 kinase domain (KD) of chronic myeloid leukemia (CML) patients who showed suboptimal response to their current tyrosine kinase inhibitor (TKI) regime and assesses their clinical value in further treatment decisions. Materials and Methods  Peripheral and/or bone marrow were collected from 791 CML patients. Ribonucleic acid was extracted, reverse transcribed, and Sanger sequencing method was utilized to detect single-nucleotide variants (SNVs) in BCR-ABL1 KD. Results  Thirty-eight different SNVs were identified in 29.8% ( n  = 236/791) patients. T315I, E255K, and M244V were among the most frequent mutations detected. In addition, one patient harbored a novel L298P mutation. A subset of patients from the abovementioned harbored compound mutations (13.3%, n  = 33/236). Follow-up data was available in 28 patients that demonstrated the efficacy of TKIs in correlation with mutation analysis and BCR-ABL1 quantitation. Molecular response was attained in 50% patients following an appropriate TKI shift. A dismal survival rate of 40% was observed in T315I-harboring patients on follow-up. Conclusion  This study shows the incidence and pattern of mutations in one of the largest sets of Indian CML patients. In addition, our findings strengthen the prognostic value of KD mutation analysis among strategies to overcome TKI resistance.

Harmonizing the craft of crafting clinically endorsed small-molecule BCR-ABL tyrosine kinase inhibitors for the treatment of hematological malignancies

The advancement and practical use of small-molecule tyrosine kinase inhibitors (TKIs) that specifically target the BCR-ABL fusion protein have introduced a revolutionary era of precision medicine for the treatment of chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). This review offers a comprehensive exploration of the synthesis, mechanisms of action, and clinical implementation of clinically validated TKIs in the context of BCR-ABL, emphasizing the remarkable strides made in achieving therapeutic precision. We delve into the intricate design and synthesis of these small molecules, highlighting the synthetic strategies and modifications that have led to increased selectivity, enhanced binding affinities, and reduced off-target effects. Additionally, we discuss the structural biology of BCR-ABL inhibition and how it informs drug design. The success of these compounds in inhibiting aberrant kinase activity is a testament to the meticulous refinement of the synthetic process. Furthermore, this review provides a detailed analysis of the clinical applications of these TKIs, covering not only their efficacy in achieving deep molecular responses but also their impact on patient outcomes, safety profiles, and resistance mechanisms. We explore ongoing research efforts to overcome resistance and enhance the therapeutic potential of these agents. In conclusion, the synthesis and utilization of clinically validated small-molecule TKIs targeting BCR-ABL exemplify the transformative power of precision medicine in the treatment of hematological malignancies. This review highlights the evolving landscape of BCR-ABL inhibition and underscores the continuous commitment to refining and expanding the therapeutic repertoire for these devastating diseases.

Real-world Imatinib Mesylate Treatment in Patients with Chronic Myeloid Leukemia: The Importance of Molecular Monitoring and the Early Molecular Response

INTRODUCTION

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder characterized by the Philadelphia (Ph) chromosome. After the introduction of imatinib mesylate (IM) in 2000, the natural history of the disease changed. Data on the treatment of CML with IM are from randomized clinical trials. Establishing whether these results can be reproduced or if caution is needed when extrapolating data to the general population with CML is essential.

OBJECTIVES

To evaluate the molecular response (MR) in patients with chronic-phase CML (CML-CP) not included in clinical studies and correlate them with the responses obtained in clinical trials.

METHODS

Between January 2007 and January 2017, 227 patients newly diagnosed with CML-CP treated with IM as first-line treatment were included. This study is an observational, retrospective, and single-center study.

RESULTS

At a median follow-up time of 7.3 years, 60.3% of the 227 patients who started IM were still on IM. Early molecular response (EMR) at 3 and 6 months was achieved by 74.2% and 65%, respectively. The median time to a MMR was nine months. The MR4.0 and MR4.5 were 67.2% and 51.1%, respectively. The overall survival (OS), progression-free survival (PFS), and event-free survival (EFS) of the patients who exclusively used IM were 91%, 91%, and 85.1%, respectively.

CONCLUSION

The results presented are similar to those described in prospective and randomized trials, demonstrating that the outcomes are reproducible in the real world. EMR at 3 and 6 months reflects better long-term responses, including higher rates of deeper molecular responses. Considering treatment costs, the absence of literature evidence of an impact on overall survival demonstrated by first-line second-generation tyrosine kinase inhibitors (TKIs), and the global OS of 85.8%, imatinib mesylate (IM) is still an excellent therapeutic option.

Loss of G0/G1 switch gene 2 (G0S2) promotes disease progression and drug resistance in chronic myeloid leukaemia (CML) by disrupting glycerophospholipid metabolism

Tyrosine kinase inhibitors (TKIs) targeting BCR::ABL1 have turned chronic myeloid leukaemia (CML) from a fatal disease into a manageable condition for most patients. Despite improved survival, targeting drug-resistant leukaemia stem cells (LSCs) remains a challenge for curative CML therapy. Aberrant lipid metabolism can have a large impact on membrane dynamics, cell survival and therapeutic responses in cancer. While ceramide and sphingolipid levels were previously correlated with TKI response in CML, the role of lipid metabolism in TKI resistance is not well understood. We have identified downregulation of a critical regulator of lipid metabolism, G0/G1 switch gene 2 (G0S2), in multiple scenarios of TKI resistance, including (1) BCR::ABL1 kinase-independent TKI resistance, (2) progression of CML from the chronic to the blast phase of the disease, and (3) in CML versus normal myeloid progenitors. Accordingly, CML patients with low G0S2 expression levels had a worse overall survival. G0S2 downregulation in CML was not a result of promoter hypermethylation or BCR::ABL1 kinase activity, but was rather due to transcriptional repression by MYC. Using CML cell lines, patient samples and G0s2 knockout (G0s2-/- ) mice, we demonstrate a tumour suppressor role for G0S2 in CML and TKI resistance. Our data suggest that reduced G0S2 protein expression in CML disrupts glycerophospholipid metabolism, correlating with a block of differentiation that renders CML cells resistant to therapy. Altogether, our data unravel a new role for G0S2 in regulating myeloid differentiation and TKI response in CML, and suggest that restoring G0S2 may have clinical utility.

De-escalation or discontinuation of tyrosine kinase inhibitor in patients with chronic myeloid leukemia: A multicentral, open-label, prospective trial in China

Background: Long-term treatment-free remission (TFR) represents a new goal for chronic myeloid leukemia (CML). Optimizing dose of tyrosine kinase inhibitors (TKIs) in the CML treatment maybe a new challenge to maintain effective and improving patients' quality of life. We hypothesized that administration of low-dose TKIs does not compromise major molecular response (MMR) in patients with CML who have a deep molecular response (DMR). Methods: We did an open-label, randomized trial at eight hospitals in China. Eligible CML-CP patients (aged 18-70 years) had shown continuous response to TKI more than 5 years and maintained MR4.5 (BCR-ABLIS ≤ 0.0032%) in recent 18 months. Patients were randomly assigned (1:1) to the TKI de-escalation group or the discontinuation group. Randomization was done with permuted blocks (block size four) and implemented through an interactive web-based randomization system. Recurrence was defined as the single sample with real time Quantitative PCR (RT-qPCR) measurement greater than 0.1% (MMR). The primary endpoint was 12-month MMR rate in patients who received de-escalation or discontinuation of TKIs. This study was registered at ClinicalTrials.gov (NCT04143087). Results: Around 125 patients were enrolled between October 23, 2019 and October 31, 2020, 62 patients received dose de-escalation of TKIs, while 63 patients in the discontinuation group. In the de-escalation group, molecular recurrence-free survival at 12 months was 88.32% (95% CI 79%-98%), whereas molecular recurrence-free survival in the discontinuation group at 12 months was 59.98% (95% CI 47-73). No progressions occurred at the data cut-off date. All 29 recurrence cases restart TKI treatment returned to MMR. Cytolytic NK cells as a proportion of lymphocyte cells were significantly increased from baseline after 6 months whether in the de-escalation or TKIs cessation group (P = 0.048, 0.001, respectively); compared with the relapsing patients, Tregs proportion was decreased (P = 0.003), and higher proportion of NK cells were found in non-relapsing patients whether in TKI de-escalation or discontinuation group (P = 0.011, 0.007, respectively). We also found that the de-escalation group showed better disease-specific HRQOL in regards to its impact on emotional functioning, fatigue, pain, and financial difficulties. Conclusion: With 88.32% MMR in 12-months follow-up after de-escalation TKIs' treatment, dose-halving could become a new treatment paradigm for CML patients who with DMR under continuing maintenance therapy with TKIs.

Association between Germline Single-Nucleotide Variants in ADME Genes and Major Molecular Response to Imatinib in Chronic Myeloid Leukemia Patients

Imatinib is the most common first-line tyrosine kinase inhibitor (TKI) used to treat chronic-phase chronic myeloid leukemia (CP-CML). However, only a proportion of patients achieve major molecular response (MMR), so there is a need to find biological factors that aid the selection of the optimal therapeutic strategy (imatinib vs. more potent second-generation TKIs). The aim of this retrospective study was to understand the contribution of germline single-nucleotide variants (gSNVs) in the achievement of MMR with imatinib. In particular, a discovery cohort including 45 CP-CML patients was analyzed through the DMET array, which interrogates 1936 variants in 231 genes related to the absorption, distribution, metabolism and excretion (ADME) process. Variants statistically significant in the discovery cohort were then tested in an extended and independent cohort of 137 CP-CML patients. Finally, a total of 7 gSNVs (ABCG1-rs492338, ABCB11-rs496550, ABCB11-rs497692, CYP2D6-rs1135840, CYP11B1-rs7003319, MAT1A-rs4934027 and SLC22A1-rs628031) and one haplotype in the ABCB11 gene were significantly associated with the achievement of MMR with first-line imatinibtreatment. In conclusion, we identified a genetic signature of response to imatinib in CP-CML patients that could be useful in selecting those patients that may benefit from starting imatinib as first-line therapy, therefore avoiding the toxicity related to second-generation TKIs.

Impact of T-cell immunity on chemotherapy response in childhood acute lymphoblastic leukemia

Although acute lymphoblastic leukemia (ALL) is highly responsive to chemotherapy, it is unknown how or which host immune factors influence the long-term remission of this cancer. To this end, we systematically evaluated the effects of T-cell immunity on Ph+ ALL therapy outcomes. Using a murine Arf-/-BCR-ABL1 B-cell ALL model, we showed that loss of T cells in the host drastically increased leukemia relapse after dasatinib or cytotoxic chemotherapy. Although ABL1 mutations emerged early during dasatinib treatment in both immunocompetent and immunocompromised hosts, T-cell immunity was essential for suppressing the outgrowth of drug-resistant leukemia. Bulk and single-cell transcriptome profiling of T cells during therapy pointed to the activation of type 1 immunity-related cytokine signaling being linked to long-term leukemia remission in mice. Consistent with these observations, interferon γ and interleukin 12 directly modulated dasatinib antileukemia efficacy in vivo. Finally, we evaluated peripheral blood immune cell composition in 102 children with ALL during chemotherapy and observed a significant association of T-cell abundance with treatment outcomes. Together, these results suggest that T-cell immunity plays pivotal roles in maintaining long-term remission of ALL, highlighting that the interplay between host immunity and drug resistance can be harnessed to improve ALL chemotherapy outcomes.

Reengineering Ponatinib to Minimize Cardiovascular Toxicity

Small molecule tyrosine kinase inhibitors (TKI) have revolutionized cancer treatment and greatly improved patient survival. However, life-threatening cardiotoxicity of many TKIs has become a major concern. Ponatinib (ICLUSIG) was developed as an inhibitor of the BCR-ABL oncogene and is among the most cardiotoxic of TKIs. Consequently, use of ponatinib is restricted to the treatment of tumors carrying T315I-mutated BCR-ABL, which occurs in chronic myeloid leukemia (CML) and confers resistance to first- and second-generation inhibitors such as imatinib and nilotinib. Through parallel screening of cardiovascular toxicity and antitumor efficacy assays, we engineered safer analogs of ponatinib that retained potency against T315I BCR-ABL kinase activity and suppressed T315I mutant CML tumor growth. The new compounds were substantially less toxic in human cardiac vasculogenesis and cardiomyocyte contractility assays in vitro. The compounds showed a larger therapeutic window in vivo, leading to regression of human T315I mutant CML xenografts without cardiotoxicity. Comparison of the kinase inhibition profiles of ponatinib and the new compounds suggested that ponatinib cardiotoxicity is mediated by a few kinases, some of which were previously unassociated with cardiovascular disease. Overall, the study develops an approach using complex phenotypic assays to reduce the high risk of cardiovascular toxicity that is prevalent among small molecule oncology therapeutics.

SIGNIFICANCE

Newly developed ponatinib analogs retain antitumor efficacy but elicit significantly decreased cardiotoxicity, representing a therapeutic opportunity for safer CML treatment.

Emerging concepts for assessing and predicting treatment-free remission in chronic myeloid leukemia patients

INTRODUCTION

In chronic myeloid leukemia (CML) patients who have reached a deep and sustained reduction of residual disease can attempt a discontinuation. The 'treatment-free remission' (TFR) has become a real long-term endpoint for 30-40% of chronic phase patients.

AREAS COVERED

In this review, we focus our attention on possible prognostic features who can predict the success of tyrosine kinase inhibitors discontinuation and how we can assess the minimal residual disease (MRD) during the TFR phase. Broad research was made on Medline, Embase and archives from EHA and ASH congresses.

EXPERT OPINION

Median duration of TKI therapy and of deep molecular response are the main prognostic factors identified in most trials and real-life experiences on discontinuation. Immunological pathways have been proposed as possible control on successful TFR as also early molecular response dynamics. Appropriate molecular monitoring by RQ-PCR in the TFR phase has been proposed by several international recommendations and digital droplet PCR (ddPCR) seems to have a possible role in the future for a better identification of candidate to this possible therapeutic strategy.

Effect of D-mannose on Philadelphia chromosome-positive leukemia cells

BACKGROUND

Although Abelson (ABL) tyrosine kinase inhibitors (TKIs) have demonstrated potency against chronic myeloid leukemia (CML), resistance to ABL TKIs can develop in CML patients after discontinuation of therapy.

OBJECTIVE

Glucose metabolism may be altered in CML cells because glucose is a key metabolite used by tumor cells. We investigated whether D-mannose treatment induced metabolic changes in CML cells and reduced CML growth in the presence of ABL TKIs.

METHODS

We investigated whether D-mannose treatment induced metabolic changes in CML cells and reduced CML growth in the presence of ABL TKIs.

RESULTS

Treatment with D-mannose for 72 h inhibited the growth of K562 cells. Combined treatment using ABL TKIs and D-mannose induced a significantly higher level of cytotoxicity in Philadelphia chromosome (Ph)-positive leukemia cells than in control cells. In the mouse model, severe toxicity was observed as evidenced by body weight loss in the ponatinib and D-mannose combination treatment groups.

CONCLUSION

Our results indicate that metabolic reprogramming may be a useful strategy against Ph-positive leukemia cells. However, caution should be exercised during clinical applications.

Treatment-free remission in patients with chronic myeloid leukemia: recommendations of the LALNET expert panel

Discontinuing TKIs in LA is the new goal, and LALNET TFR recommendations for CML patients are an unmet need.

TFR recommendations adapted to LA needs will make discontinuation feasible and safe in real life in the region.

Tyrosine kinase inhibitors (TKIs) have dramatically changed the survival of chronic myeloid leukemia (CML) patients, and treatment-free remission (TFR) has recently emerged as a new goal of CML treatment. The aim of this work was to develop recommendations for TKI discontinuation in Latin America (LA), outside of clinical trials. A working group of CML experts from LA discussed 22 questions regarding TFR and reached a consensus for TFR recommendations in the region. TFR is indicated in patients in first chronic phase, with typical BCR-ABL transcripts, under TKI treatment of a minimum of 5 years, in sustained deep molecular response (DMR; molecular response 4.5 [MR4.5]) for 2 years. Sustained DMR must be demonstrated on at least 4 international reporting scale quantitative polymerase chain reaction (PCR) tests, separated by at least 3 months, in the immediate prior 2 years. After second-line therapy, TFR is indicated in previously intolerant, not resistant, patients. Molecular monitoring is recommended monthly for the first 6 months, every 2 to 3 months from months 7 to 12, and every 3 months during the second year, indefinitely. Treatment should be reintroduced if major molecular response is lost. Monitoring of withdrawal syndrome, glucose levels, and lipid profile is recommended after discontinuation. After TKI reintroduction, molecular monitoring is indicated every 2 to 3 months until MR4.0 achievement; later, every 3 to 6 months. For the TFR attempt, having standardized and reliable BCR-ABL PCR tests is mandatory. These recommendations will be useful for safe discontinuation in daily practice and will benefit patients who wish to stop treatment in emergent regions, in particular, with TKI-related chronic adverse events.

Assessment of molecular response to tyrosine kinase inhibitors in Tunisian Patients with Chronic Myeloid Leukemia

AIM

This study was carried out to assess the minimal residual disease in Tunisian patients with chronic myeloid leukemia (CML) treated with tyrosine kinase inhibitors in routine clinical practice, to recognize potentially eligible carrier for treatment discontinuation, based on a molecular response (MR).

PATIENTS AND METHODS

A retrospective study was carried out in the Hospital University of Sfax, south of Tunisia from January 2016 to October 2020, including all CML patients in the chronic phase at diagnosis, treated with TKI (tyrosine kinase inhibitors) for a minimum duration of 6 months. Quantitative assessment of the BCR-ABL transcript was performed using the Cepheid Xpert BCR-ABL ultra-assay. Molecular response and outcome were evaluated, according to the European Leukemia Net guidelines.

RESULTS

A total of 162 CML patients were carried out. The median age was 50 years, the sex ratio M/F was 1.62. The rate of cumulative EMR; MMR and DMR was 80.8%; 73.8% and 55.9% respectively. According to the ELN criteria, 141 CML patients were evaluable. Optimal, suboptimal response and failure were noted in 81 (57.4%), 33(23.4%), and 27(19.1%) patients, respectively. Overall survival (OS) and progression-free survival (PFS) were 96.3% and 85%. Risk factors for an event (death/progression) were lack of EMR, MMR, and DMR (P < 0.05). Among 149 patients with sustained DMR; 14 (8.6%) CML patients have discontinued TKI therapy.

CONCLUSION

Despite the limit of our study (duration and size), the available real-life molecular responses with TKI therapy should be considered to identify potentially CML patients eligible for discontinuation of TKI therapy.

Novel Treatment Strategies Utilizing Immune Reactions against Chronic Myelogenous Leukemia Stem Cells

Simple Summary

Although tyrosine kinase inhibitors (TKIs) are highly effective in the treatment of patients with chronic myelogenous leukemia (CML), leukemic stem cells (LSCs) are known to be resistant to TKIs. As a result, the application of immunotherapies against LSCs may cure CML.

Abstract

Introduction of tyrosine kinase inhibitors (TKIs) has improved the prognosis of patients with chronic myelogenous leukemia (CML), and treatment-free remission (TFR) is now a treatment goal. However, about half of the patients experience molecular relapse after cessation of TKIs, suggesting that leukemic stem cells (LSCs) are resistant to TKIs. Eradication of the remaining LSCs using immunotherapies including interferon-alpha, vaccinations, CAR-T cells, and other drugs would be a key strategy to achieve TFR.

Treatment-Free Remission in Chronic Myeloid Leukemia: Can We Identify Prognostic Factors?

Simple Summary

Chronic myeloid leukemia (CML) is a blood cancer. Unlike other cancers CML treatment is lifelong and many patients experience side effects. For those patients who respond well to treatment and achieve deep molecular remission, quality of life is impacted because of continuous treatment. In this review, we look at emerging clinical trials which aim to investigate which patients can safely stop treatment. Treatment-free remission is the ultimate goal for CML patients, but there is still a gap in our knowledge as to why some patients can achieve treatment-free remission, while others relapse when treatment is stopped. Here we discuss if there are any prognostic factors that can predict the best candidates who qualify for treatment discontinuation, with a view to keeping them in remission.

Abstract

Following the development of tyrosine kinase inhibitors (TKI), the survival of patients with chronic myeloid leukaemia (CML) drastically improved. With the introduction of these agents, CML is now considered a chronic disease for some patients. Taking into consideration the side effects, toxicity, and high cost, discontinuing TKI became a goal for patients with chronic phase CML. Patients who achieved deep molecular response (DMR) and discontinued TKI, remained in treatment-free remission (TFR). Currently, the data from the published literature demonstrate that 40–60% of patients achieve TFR, with relapses occurring within the first six months. In addition, almost all patients who relapsed regained a molecular response upon retreatment, indicating TKI discontinuation is safe. However, there is still a gap in understanding the mechanisms behind TFR, and whether there are prognostic factors that can predict the best candidates who qualify for TKI discontinuation with a view to keeping them in TFR. Furthermore, the information about a second TFR attempt and the role of gradual de-escalation of TKI before complete cessation is limited. This review highlights the factors predicting success or failure of TFR. In addition, it examines the feasibility of a second TFR attempt after the failure of the first one, and the current guidelines concerning TFR in clinical practice.

Novel developments in chronic myeloid leukaemia

PURPOSE OF REVIEW

Despite unprecedented challenges during the preceding year, there have been a wide range of significant advances in the field of chronic myeloid leukaemia. In this review article we highlight papers reporting on some of the most important developments over the last year, both with regards to the clinical management of patients with chronic myeloid leukaemia, as well as studies that help to increase our understanding of the pathophysiology of the disease. We have performed a PubMed search to identify important papers and abstracts listed over the last year and have included additional papers published prior to this, where relevant, to provide context.

RECENT FINDINGS

We comment on novel biomarkers for treatment free remission as well as recent results from second generation Tyrosine Kinase Inhibitor (TKI) discontinuation studies. We discuss new techniques that are being used to assess TKI resistance as well as reviewing novel and emerging approaches to the management of resistant patients, including the use of combination therapies.

SUMMARY

This review highlights some of the most important research to have been reported over the last year in the field of chronic myeloid leukaemia, encompassing emerging diagnostic techniques, biomarkers and novel therapeutic options.

Treatment-Free Remission-A New Aim in the Treatment of Chronic Myeloid Leukemia

Tyrosine kinases inhibitors (TKIs) revolutionized chronic myeloid leukemia (CML) treatment for many years, prolonging patients' life expectancy to be comparable to age-matched healthy individuals. According to the latest the European LeukemiaNet (ELN) recommendations, CML treatment aims to achieve long-term remission without treatment (TFR), which is feasible in more than 40% of patients. Nearly all molecular relapses occur during the first 6 months after TKI withdrawal and do not progress to clinical relapse. The mechanisms that are responsible for CML relapses remain unexplained. It is suggested that maintaining TFR is not directly related to the total disposing of the gene transcript BCR-ABL1, but it might be a result of the restoration of the immune surveillance in CML. The importance of the involvement of immunocompetent cells in the period of TKI withdrawal is also emphasized by the presence of specific symptoms in some patients with "withdrawal syndrome". The goal of this review is to analyze data from studies regarding TFRs in order to characterize the elements of the immune system of patients that might prevent CML molecular relapse. The role of modern droplet digital polymerase chain reaction (ddPCR) and next-generation sequencing (NGS) in better identification of low levels of BCR-ABL1 transcripts was also taken into consideration for refining the eligibility criteria to stop TKI therapy.

Early BCR-ABL1 kinetics are predictive of subsequent achievement of treatment-free remission in chronic myeloid leukemia

With treatment-free remission (TFR) rapidly becoming the ultimate goal of therapy in chronic myeloid leukemia (CML), there is a need to develop strategies to maximize sustained TFR by improving our understanding of its key determinants. Chronic-phase CML patients attempting TFR were evaluated to identify the impact of multiple variables on the probability of sustained TFR. Early molecular response dynamics were included as a predictive variable, assessed by calculating the patient-specific halving time of BCR-ABL1 after commencing tyrosine kinase inhibitor (TKI) therapy. Overall, 115 patients attempted TFR and had ≥12 months of follow-up. The probability of sustained TFR, defined as remaining in major molecular response off TKI therapy for 12 months, was 55%. The time taken for the BCR-ABL1 value to halve was the strongest independent predictor of sustained TFR: 80% in patients with a halving time of <9.35 days (first quartile) compared with only 4% if the halving time was >21.85 days (last quartile) (P < .001). The e14a2 BCR-ABL1 transcript type and duration of TKI exposure before attempting TFR were also independent predictors of sustained TFR. However, the BCR-ABL1 value measured at 3 months of TKI was not an independent predictor of sustained TFR. A more rapid initial BCR-ABL1 decline after commencing TKI also correlated with an increased likelihood of achieving TFR eligibility. The association between sustained TFR and the time taken for BCR-ABL1 to halve after commencing TKI was validated using an independent dataset. These data support the critical importance of the initial kinetics of BCR-ABL1 decline for long-term outcomes.

Long-term treatment-free remission in patients with chronic myeloid leukemia after second-line nilotinib: ENESTop 5-year update

The ENESTop study evaluated treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML) in chronic phase who had received ≥3 years of tyrosine kinase inhibitor therapy and achieved sustained deep molecular response only after switching from imatinib to nilotinib. After 1-year nilotinib consolidation, 126 patients attempted TFR. At 48 weeks (primary analysis), 57.9% (73/126) were in TFR. In the present analysis at 5 years, 42.9% (54/126) were in TFR. Since the 48-week analysis, among patients who left the TFR phase, 58% (11/19) did not have a loss of molecular response and discontinued for other reasons. Of the 59 patients who reinitiated nilotinib upon loss of major molecular response (MMR) or confirmed loss of MR⁴, 98.3% regained MMR, 94.9% regained MR⁴, and 93.2% regained MR^4.5. Overall adverse event rates decreased over the 5 years of TFR. In patients reinitiating nilotinib, there was a cumulative increase in cardiovascular events with longer nilotinib exposure. No disease progression or CML-related deaths were reported. Overall, these results confirm the durability and safety of TFR for patients receiving second-line nilotinib. Cardiovascular risk should be carefully managed, particularly when reinitiating treatment after TFR.

Sema4D correlates with tumour immune infiltration and is a prognostic biomarker in bladder cancer, renal clear cell carcinoma, melanoma and thymoma

Sema4D, a member of the immune semaphorin family, plays crucial roles in the immune regulation, bone resorption and nervous system. It is also involved in angiogenesis and tumour progression. However, systemic studies on the correlation between Sema4D expression and the immune infiltration or clinical outcomes in tumours are still limited. Here, we analysed the landscape of Sema4D expression and its prognostic value in the cancer genome atlas pan-cancer as well as the correlation between Sema4D and immune cell infiltration by Tumour Immune Estimation Resource and Gene Expression Profiling interactive analysis online tools. Results showed that a higher Sema4D expression was significantly correlated with a favourable overall survival in diverse solid tumours including bladder cancer (Hazards Ratio (HR)=0.68, p = .0095), kidney renal clear cell carcinoma (HR = 0.61, p = .0016), melanoma (HR = 0.58, p = 6.6e-05) and thymoma (HR = 0.1, p = .011). Interestingly, Sema4D expression has positive correlation with various tumour infiltrating immune cells and immune cell biomarkers in these tumours. These results suggest that Sema4D could be a prospective biomarker for calculating hazard ratio of tumour patients and their tumour immune infiltration levels.

Mutational landscape of chronic myeloid leukemia: more than a single oncogene leukemia

The BCR-ABL1 fusion gene, which causes aberrant kinase activity and uncontrolled cell proliferation, is the hallmark of chronic myeloid leukemia (CML). The development of tyrosine kinase inhibitors (TKI) that target the BCR-ABL oncoprotein has led to dramatic improvement in CML management. However, some challenges remain to be addressed in the TKI era, including patient stratification and the selection of frontline TKIs and CML progression. Additionally, with the emerging goal of treatment-free remission (TFR) in CML management, biomarkers that predict the outcomes of stopping TKI remain to be identified. Notably, recent reports have revealed the power of genome screening in understanding the role of genome aberrations other than BCR-ABL1 in CML pathogenesis. These studies have discovered the presence of disease-phase specific mutations and linked certain mutations to inferior responses to TKI treatment and CML progression. A personalized approach that incorporates genetic data in tailoring treatment strategies has been successfully implemented in acute leukemia, and it represents a promising approach for the management of high-risk CML patients. In this article, we will review current knowledge about the mutational profile in different phases of CML as well as patterns of mutational dynamics in patients having different outcomes. We highlight the effects of somatic mutations involving certain genes (e.g. epigenetic modifiers) on the outcomes of TKI treatment. We also discuss the potential value of incorporating genetic data in treatment decisions and the routine care of CML patients as a future direction for optimizing CML management.

Leukemic stem cells shall be searched in the bone marrow before "tyrosine kinase inhibitor-discontinuation" in chronic myeloid leukemia

BACKGROUND

Leukemic stem cells (LSCs) of chronic myeloid leukemia (CML), persisting in the bone marrow (BM) niche, could be responsible for the relapses within the patients of whom the treatment-free remission (TFR) had been attempted. We assessed the presence of the CML LSCs in the peripheral blood (PB) and concurrently in the BM in the patients with chronic-phase CML (CP CML).

PATIENTS AND METHODS

Thirty-eight patients with CP CML were included into the study. CD45⁺ /CD34⁺ /CD38^- cells with positive CD26 expression were considered as CML LSCs (CD26⁺ LSC) by using multiparameter flow cytometry (FCM).

RESULTS

Mean BCR-ABL, PB LSC, and BM LSC were 58.528 IS (37.405-83.414 IS), 237.5 LSC/μL (16-737.5 LSC/μL), and 805 LSC/10⁶  WBCs (134.6-2470 LSC/10⁶  WBCs), respectively, in newly diagnosed CML patients. In the patients with BCR-ABL positive hematopoiesis, mean BCR-ABL, PB LSCs, and BM LSCs were 30.09 IS (0.024-147.690 IS), 13.5 LSC/μL (0-248.7 LSC/μL) and 143.5 LSC/10⁶  WBCs (9-455.2 LSC/10⁶  WBCs), respectively. No CML LSCs were detected in PB of patients who achieved deep molecular response (DMR). BM LSCs of the patients who were in DMR were 281.1 LSC/10⁶  WBCs (3.1-613.7 LSC/10⁶  WBCs). The amount of PB LSCs was highest in patients with newly diagnosed CML (P < .001).

CONCLUSION

LSCs persisted in the BM of the patients with DMR, whereas there was no LSCs in the peripheral blood. The investigation of the CML LSCs in bone marrow before deciding TKI discontinuation could be justified to achieve and maintain stable TFR.

Treatment-free remission following frontline nilotinib in patients with chronic phase chronic myeloid leukemia: 5-year update of the ENESTfreedom trial

The ENESTfreedom trial assessed the feasibility of treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase (CML-CP) following frontline nilotinib treatment. Results for long-term outcomes after a 5-year follow-up are presented herein. Patients who had received ≥2 years of frontline nilotinib therapy and achieved MR^4.5 underwent a 1-year nilotinib treatment consolidation phase before attempting TFR. At the 5-year data cut-off, 81/190 patients entering the TFR phase (42.6%) were still in TFR, with 76 (40.0%) in MR^4.5. Patients who lost major molecular response (MMR) entered a treatment re-initiation phase; 90/91 patients entering this phase (98.9%) regained MMR and 84/91 patients (92.3%) regained MR^4.5. The Kaplan–Meier estimated treatment-free survival rate at 5 years was 48.2%. No disease progression or CML-related deaths were reported. Whereas the incidence of adverse events (AEs) declined from 96 weeks following the start of TFR, an increase in AE frequency was observed for patients in the treatment re-initiation phase. Low Sokal risk score, BCR-ABL1^IS levels at 48 weeks of TFR and stable MR^4.5 response for the first year of TFR were associated with higher TFR rates. Overall, these results support the efficacy and safety of attempting TFR following upfront nilotinib therapy of >3 years in patients with CML-CP.

Improved gene delivery to K-562 leukemia cells by lipoic acid modified block copolymer micelles

Although there has been substantial progress in the research field of gene delivery, there are some challenges remaining, e.g. there are still cell types such as primary cells and suspension cells (immune cells) known to be difficult to transfect. Cationic polymers have gained increasing attention due to their ability to bind, condense and mask genetic material, being amenable to scale up and highly variable in their composition. In addition, they can be combined with further monomers exhibiting desired biological and chemical properties, such as antioxidative, pH- and redox-responsive or biocompatible features. By introduction of hydrophobic monomers, in particular as block copolymers, cationic micelles can be formed possessing an improved chance of transfection in otherwise challenging cells. In this study, the antioxidant biomolecule lipoic acid, which can also be used as crosslinker, was incorporated into the hydrophobic block of a diblock copolymer, poly{[2-(dimethylamino)ethyl methacrylate]101-b-[n-(butyl methacrylate)124-co-(lipoic acid methacrylate)22]} (P(DMAEMA101-b-[nBMA124-co-LAMA22])), synthesized by RAFT polymerization and assembled into micelles (LAMA-mic). These micelles were investigated regarding their pDNA binding, cytotoxicity mechanisms and transfection efficiency in K-562 and HEK293T cells, the former representing a difficult to transfect, suspension leukemia cell line. The LAMA-mic exhibited low cytotoxicity at applied concentrations but demonstrated superior transfection efficiency in HEK293T and especially K-562 cells. In-depth studies on the transfection mechanism revealed that transfection efficiency in K-562 cells does not depend on the specific oncogenic fusion gene BCR-ABL alone. It is independent of the cellular uptake of polymer-pDNA complexes but correlates with the endosomal escape of the LAMA-mic. A comparison of the transfection efficiency of the LAMA-mic with structurally comparable micelles without lipoic acid showed that lipoic acid is not solely responsible for the superior transfection efficiency of the LAMA-mic. More likely, a synergistic effect of the antioxidative lipoic acid and the micellar architecture was identified. Therefore, the incorporation of lipoic acid into the core of hydrophobic-cationic micelles represents a promising tailor-made transfer strategy, which can potentially be beneficial for other difficult to transfect cell types.

Health state utility and quality of life measures in patients with chronic myeloid leukemia in France

PURPOSE

Tyrosine kinase inhibitors (TKIs) have dramatically improved the prognosis of chronic myeloid leukemia (CML). We aimed to assess health state utility and quality of life (QoL) in French patients with CML in real-life setting, to study the determinants of utility score and to compare health-related QoL values to general population norms.

METHODS

We conducted a cross-sectional study in 412 patients with CML. Data were collected by electronic survey. Three patient-reported outcomes questionnaires were used: EORTC QLQ-C30, EORTC QLQ-CML24 and EuroQol EQ-5D-3L. Health state utility values were computed using the French value set. We computed deviations from reference norms from the general population. We studied the determinants of health utility score using multiple regression models.

RESULTS

The mean utility score (SD) was 0.72 (0.25) in the chronic phase and 0.84 (0.21) in treatment-free remission, with marked variations by gender. Patients with CML had a deviation from the reference norm of -0.15 on average (SD: 0.25). In terms of QoL, social functioning, role functioning and cognitive functioning were notably impacted with a mean difference of -16.0, -13.1 and -11.7 respectively. Fatigue, dyspnea and pain were the symptoms with the highest deviation from general population norms (mean difference of 20.6, 14.0 and 8.3 respectively). In the multiple regression analysis, fatigue was the most important independent predictor of the utility score.

CONCLUSION

Although TKIs prevent the disease from progressing and even allow remission without treatment, QoL in patients with CML is notably altered. The utility scores deteriorate with CML symptoms.

Transitional dynamics of cancer stem cells in invasion and metastasis

At the onset, few cancer cells amidst the tumor bulk, identified as cancer stem cells (CSCs) or early disseminated cancer cells (eDCCs) are capable of survival post conventional therapy and persist as minimal residual disease (MRD). Metastatic subclones emerge both early and late in the life of primary tumor ensuing an ongoing regional clonal evolution of progenitor cells in metastatic and primary tumors. In the last decade, multiple studies proposed various identities of stem-like cells that undergo transitions to adapt to the changing microenvironment as the disease progresses. This review advocates with substantial evidence the dynamic model of tumor propagation by exploring the specific cell types, reversible phenotypic plasticity between the tumorigenic leader seeds and the supporting follower cancer cells both in circulation and in solid tissue to accurately decipher tumor promoting clones and its role in metastatic dissemination and tumor re-growth. (142 words).

Real-world tyrosine kinase inhibitor treatment pathways, monitoring patterns and responses in patients with chronic myeloid leukaemia in the United Kingdom: the UK TARGET CML study

Management of chronic myeloid leukaemia (CML) has recently undergone dramatic changes, prompting the European LeukemiaNet (ELN) to issue recommendations in 2013; however, it remains unclear whether real-world CML management is consistent with these goals. We report results of UK TARGET CML, a retrospective observational study of 257 patients with chronic-phase CML who had been prescribed a first-line TKI between 2013 and 2017, most of whom received first-line imatinib (n = 203). Although 44% of patients required ≥1 change of TKI, these real-world data revealed that molecular assessments were frequently missed, 23% of patients with ELN-defined treatment failure did not switch TKI, and kinase domain mutation analysis was performed in only 49% of patients who switched TKI for resistance. Major molecular response (MMR; BCR-ABL1IS ≤0·1%) and deep molecular response (DMR; BCR-ABL1IS ≤0·01%) were observed in 50% and 29%, respectively, of patients treated with first-line imatinib, and 63% and 54%, respectively, receiving a second-generation TKI first line. MMR and DMR were also observed in 77% and 44% of evaluable patients with ≥13 months follow-up, receiving a second-generation TKI second line. We found little evidence that cardiovascular risk factors were considered during TKI management. These findings highlight key areas for improvement in providing optimal care to patients with CML.

Involvement of Oxidative Stress in Resistance to Tyrosine-Kinase Inhibitors Therapy in Chronic Myeloid Leukemia

Oxidative stress involves disruption of the cellular redox status through excessive production of reactive oxygen species or through deficiency in the cellular antioxidant capacity. It is involved in the pathogeny of multiple entities (hematological diseases, metabolic disorders, cardiovascular and renal pathology etc.), as well as in the pharmacokinetics of specific treatments for these pathologies. Chronic myeloid leukemia is a chronic myeloproliferative disease for which current standard treatment is BCR-ABL tyrosine kinase inhibitors. The innovation of this therapy has significantly improved life expectancy for patients with chronic myeloid leukemia, but in some cases, this treatment becomes ineffective, installing the resistance to tyrosine kinase inhibitors therapy. There were described two types of tyrosin kinase inhibitors resistance: primary and secondary resistance. In the present paper we proposed to evaluate the involvement of oxidative in the resistance to tyrosine kinase inhibitors therapy, in the clonal instability in chronic myeloid leukemia and in the progression of the disease to an advanced stage. We concluded that oxidative stress can play a dual role in the evolution of chronic myeloid leukemia: on the one hand it can promote genomic instability and accelerate the progression of the disease to advanced stages associated with tyrosin kinase inhibitors resistance and, on the other hand, it can contribute to leukemic cell apoptosis. It seems to be outlined a fragile balance between the pro- and anti-apoptotic effects of the reactive oxygen species, closely related to their level in the leukemic cells.

On the road to treatment-free remission in chronic myeloid leukemia: what about 'the others'?

INTRODUCTION

The treatment of chronic myeloid leukemia (CML) has been drastically changed by the approval of tyrosine kinase inhibitors (TKIs). CML is now managed as a chronic disease requiring both long-term treatment and close molecular monitoring in the majority of patients.

AREAS COVERED

Evidence suggests that in a substantial number of patients who have achieved a stable deep molecular response (DMR), TKI treatment can be safely discontinued without loss of response. Therefore, treatment-free remission (TFR), through the achievement of a DMR, is increasingly regarded as a feasible treatment goal in about 20% to 40% CML patients. Nevertheless, a proportion of patients with chronic-phase CML treated with TKIs remain in stable MMR and do not achieve a DMR.

EXPERT OPINION

We provide prospective views on how it is possible to optimize treatment for patients in stable MMR but not in DMR in order to finalize the therapeutic strategy.

In Vitro Comparison of the Effects of Imatinib and Ponatinib on Chronic Myeloid Leukemia Progenitor/Stem Cell Features

Background

The development of molecularly tailored therapeutic agents such as the BCR/ABL-active tyrosine kinase inhibitors (TKi) resulted in an excellent treatment option for chronic myeloid leukemia (CML) patients. However, following TKi discontinuation, disease relapses in 40–60% of patients, an occurrence very likely due to the persistence of leukemic stem cells that are scarcely sensitive to TKi. Nevertheless, TKi are still the only current treatment option for CML patients.

Objective

The aim of this study was to compare the effects of TKi belonging to different generations, imatinib and ponatinib (first and third generation, respectively), on progenitor/stem cell expansion potential and markers.

Patients and Methods

We used stabilized CML cell lines (KCL22, K562 and LAMA-84 cells), taking advantage of the previous demonstration of ours that cell lines contain cell subsets endowed with progenitor/stem cell properties. Primary cells explanted from CML patients were also used. The effects of TKi on the expression of stem cell related genes were compared by quantitative PCR. Flow cytometry was performed to evaluate aldehyde-dehydrogenase (ALDH) activity and the expression of cluster of differentiation (CD) cell surface hematopoietic stem cell markers. Progenitor/stem cell potential was estimated by serial colony formation ability (CFA) assay.

Results

Ponatinib was more effective than imatinib for the reduction of cells with ALDH activity and progenitor/stem cell potential of CML patient-derived cells and cell lines. Furthermore, ponatinib was more effective than imatinib in reducing the percentage of CD26-expressing cells in primary CML cells, whereas imatinib and ponatinib showed similar efficacy on KCL22 cells. Both drugs strongly upregulated NANOG and SOX2 in CML cell lines, but in KCL22 cells this upregulation was significantly lower with ponatinib than with imatinib, an outcome compatible with a lower level of enrichment of the stem cell compartment upon ponatinib treatment.

Conclusion

Ponatinib seems to target CML progenitor/stem cells better than imatinib.

Electronic supplementary material

The online version of this article (10.1007/s11523-020-00741-x) contains supplementary material, which is available to authorized users.

Re-defining Prognosis of Hematological Malignancies by Dynamic Response Assessment Methods: Lessons Learnt in Chronic Myeloid Leukemia, Hodgkin Lymphoma, Diffuse Large B Cell Lymphoma and Multiple Myeloma

Risk-stratification is an essential management tool in defining prognosis of haematological neoplasms, both from patient and physician perspective. We define a new prognostic term "Dynamic Response Assessment Method(s) (DRAM)" as "method(s) used for re-stratifying disease prognosis at fixed intervals during the treatment course". The risk stratification is done after a fixed duration of treatment or chemotherapy cycles using sensitive techniques. The information obtained then can be used for further therapeutic decisions and prognostication. Currently, there is enough evidence that response to treatment improves the prognostic value of baseline disease variables in the management of Chronic Myeloid Leukemia, Hodgkin lymphoma, Diffuse Large B cell Lymphoma, and Multiple Myeloma. Through this review, we discuss the current evidence based application of "DRAM" to guide therapeutic decisions in these malignancies. We also discuss how the results of "DRAM" can be incorporated for redefining prognosis and counselling the patients with these selected hematologic malignancies.

Low-dose tyrosine kinase inhibitors before treatment discontinuation do not impair treatment-free remission in chronic myeloid leukemia patients: Results of a retrospective study

BACKGROUND

Long-term treatment-free remission (TFR) represents a new goal for chronic myeloid leukemia (CML). In clinical practice, tyrosine kinase inhibitor (TKI) dose reductions can be considered a means of preventing adverse effects and improving quality of life. We hypothesized that administration of low-dose TKIs before treatment discontinuation does not impair TFR in patients with CML who have a deep molecular response (DMR, ≥MR⁴ ).

METHODS

We conducted a retrospective analysis of 77 patients with CML who discontinued treatment with TKIs. Twenty-six patients had been managed with low-dose TKIs before stopping treatment. Patients were to be exposed to TKIs for ≥5 years and to low-dose TKIs for ≥1 year and in DMR for ≥2 years. The loss of major molecular response (MMR) was considered a trigger for restarting therapy.

RESULTS

In the low-dose group, 61.5% of patients received second-generation TKIs, and dose reduction was ≥50% for 65.4% of patients. With a median follow-up of 61.5 months, TFR at 12 months was 56.8% in the full-dose TKI group and 80.8% in the low-dose group, and TFR at 60 months was 47.5% and 58.8%, respectively. The median time to molecular recurrence (≥MMR) from TKI discontinuation in the entire cohort was 6.2 months. All patients quickly achieved MMR after resuming TKI therapy. Results appear independent of both dose reduction and potential pretreatment with interferon-α.

CONCLUSION

This retrospective study shows that TFR was not impaired by low-dose TKI regimens before TKI cessation in Patients with CML. Nevertheless, prospective randomized clinical trials must be undertaken to analyze the probability of successful TFR in patients managed with TKI dose de-escalation strategies before TKI discontinuation.

Budget impact analysis of treatment-free remission in nilotinib-treated Japanese chronic myeloid leukemia patients

Treatment‐free remission (TFR), in which patients discontinue pharmacotherapy and remain in molecular remission, is an emerging treatment goal for patients with chronic myeloid leukemia (CML). Attainment of TFR requires an increased frequency of molecular monitoring, to ensure that patients maintain a deep molecular response. The objective of this analysis was to assess the economic impact of stopping nilotinib among Japanese TFR‐eligible patients. A Markov model evaluated the economic impact of TFR among the study population, TFR‐eligible CML patients diagnosed since 2012. The model compared patients who had discontinued tyrosine kinase inhibitor (TKI) treatment (ie, attempted TFR) with patients that continued TKI treatment. A 3‐y time horizon was modeled from a Japanese public payer perspective. Costs associated with drug treatment, hospital/physician visits, and molecular monitoring were considered. TFR‐eligible patients were calculated from Japanese CML incidence rates and efficacy was derived from nilotinib trials. Japanese co‐payment maximums were utilized to assess the patient perspective. An estimated 761 and 140 patients were eligible for first‐ and second‐line nilotinib, respectively, in 2019. Assuming that 100% of eligible patients complied, TFR was associated with cost savings of ¥7 625 174 640 (US$66 567 775) over 3 y. In scenarios with reduced willingness to attempt TFR, cost savings persisted. Achievement of TFR was estimated to markedly reduce out‐of‐pocket expenses for CML patients, regardless of the timing of relapse. Stopping nilotinib for TFR‐eligible patients in Japan may result in significant cost savings to both payers and patients. Monitoring costs contributed little to overall annual costs and decreased over time.

Long-Term Survival, Vascular Occlusive Events and Efficacy Biomarkers of First-Line Treatment of CML: A Meta-Analysis

Large randomized clinical trials and prior meta-analyses indicate that second-generation BCR-ABL tyrosine kinase inhibitors (TKIs) improve surrogate biomarkers in patients with chronic myeloid leukemia (CML) without providing survival benefits. The objective is to evaluate the long-term efficacy and the occurrence of vascular occlusion with second-generation BCR-ABL TKIs compared with imatinib in patients with CML. Three scientific databases, a clinical registry and abstracts from congress were searched to identify all randomized controlled trials that compared a second-generation BCR-ABL TKI to imatinib in patients with CML. Outcomes extracted were overall survival, major molecular response and complete cytogenetic response, arterial occlusive events and venous thromboembolism. These data were synthesized by odds ratios using a fixed-effect model. This meta-analysis included 4659 participants from 14 trials. Second-generation BCR-ABL TKIs did not improve overall survival compared with imatinib, even at longer follow-up (OR, 1.17 (95% CI, 0.91–1.52)). They improved surrogate biomarkers at 12 and 24 months but increased the risk of arterial occlusion (OR_PETO, 2.81 (95% CI, 2.11–3.73)). The long-term benefits of second-generation TKIs are restricted to surrogate outcomes and do not translate into prolonged survival compared to imatinib. Given the long-term use, frontline therapy should be chosen carefully, with special attention to the patients’ quality of life and cardiovascular risks.

Quercetin Promotes Cell Cycle Arrest and Apoptosis and Attenuates the Proliferation of Human Chronic Myeloid Leukemia Cell Line-K562 Through Interaction with HSPs (70 and 90), MAT2A and FOXM1

BACKGROUND

Chronic Myeloid Leukaemia (CML) starts in certain blood-forming cells of the bone marrow when cells acquire Philadelphia chromosome. Nowadays, scientists attempt to find novel and safe therapeutic agents and approaches for CML therapy using Tyrosine Kinase Inhibitors (TKIs), CML conventional treatment agents, has some restrictions and also adverse effects. Recently, it has been proposed that phytochemicals, such as flavonoids due to their low side effects and notable safety have the potential to be used for CML therapy.

MATERIALS AND METHODS

K-562 cells were exposed with three concentrations of the querectin (10, 40 and 80µM) for 12, 24 and 48 hours. After that, these cells apoptosis rate was estimated using Annexin-V/PI staining and flowcytometry analysis, and their proliferation rate was evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT). Finally, the expression of the 70 and 90 kilodalton heat shock proteins (HSP70 and 90), methionine adenosyltransferase 2A (MAT2A), Forkhead box protein M1 (FOXM1), caspase-3 and -8, Bcl-X(L) and Bax involved in leukemic cells survival and proliferation was assessed using Real-Time PCR within 12, 24 and 48 hours after exposure with quercetin 40 and 80µM.

RESULTS

Considering consequences, querecetin induced apoptosis in K-562 cells, and also abrogated these cells proliferation. On the other hand, RT-PCR results showed a reduction in some of the candidate genes expression, especially HSP70, Bcl-X(L) and FOXM1, when cells were treated with quercetin 40 and 80µM. Also, Bax, caspase-3 and caspase-8 expression was significantly improved in K-562 cells upon quercetin exposure.

CONCLUSION

We concluded that CML therapy by querecetin due to its anti-proliferative and anti-survival potentials could lead to the promising therapeutic outcome through targeting major survival and proliferation involved genes expression.

Cost effectiveness of therapeutic drug monitoring for imatinib administration in chronic myeloid leukemia

BACKGROUND

Imatinib mesylate (IM) is a first-line treatment option for patients with chronic myeloid leukemia (CML). Patients who fail or are intolerant to IM therapy are treated with more expensive second and third-generation tyrosine kinase inhibitors. Patients show wide variation in trough concentrations in response to standard dosing. Thus, many patients receive subtherapeutic or supratherapeutic doses. Therapeutic drug monitoring (TDM) may improve dose management that, in turn, may reduce costs and improve outcomes. However, TDM also adds to the cost of patient care. The objective of this study was to determine the cost-effectiveness of TDM for generic IM therapy.

METHODS

We developed a microsimulation model for the trough plasma concentration of IM which is related to a cytogenetic or molecular response. We compared two cohorts: one with TDM and one without TDM (NTDM). The lifetime incremental cost-effectiveness ratio (ICER) was calculated using quality-adjusted life years (QALYs) as the effectiveness measure. One-way and probabilistic sensitivity analyses were performed.

RESULTS

The lifetime cost and QALY of treatment with TDM were $2,137K [95% Ci: 2,079K; 2,174K] and 12.37 [95% CI: 12.07; 12.55], respectively. The cost and QALY of NTDM were $2,132K [95% CI: 2,091K; 2,197K] and 12.23 [95% CI: 11.96; 12.50], respectively. The incremental cost and QALY for TDM relative to NTDM was $4,417 [95% CI: -52,582; 32,097]) and 0.15 [95% CI: -0.13; 0.28]. The ICER for TDM relative to NTDM was $30,450/QALY. Probabilistic sensitivity analysis showed that TDM was cost-effective relative to NTDM in 90% of the tested scenarios at a willingness-to-pay threshold of $100,000/QALY.

CONCLUSIONS

Although the impact of TDM is modest, the cost-effectiveness over a lifetime horizon (societal perspective, ($30,450/QALY) falls within the acceptable range (< $100k/QALY).

Imatinib is still recommended for frontline therapy for CML

This article has a companion Counterpoint by Cortes.

Paediatric chronic myeloid leukaemia: Is it really a different disease?

Paediatric chronic myeloid leukaemia (CML) has biological and clinical differences from adult CML. Management of paediatric CML presents unique challenges in growing children, and there are no specific guidelines for paediatric CML. This review focusses on the clinical characteristics, diagnostic issues and management of paediatric CML. Major studies that provide the basis of managing paediatric CML are summerized here. Studies conducted on adult CML patients were used to guide the management of places where studies were lacking in paediatric CML. Recently, dasatinib and nilotinib have been approved for treatment of paediatric CML, and their role has been discussed in the current management perspective. Allogeneic transplant, fertility and vaccination in paediatric CML, have also been discussed.

Using healthcare claims data to analyze the prevalence of BCR-ABL-positive chronic myeloid leukemia in France: A nationwide population-based study

Background

Data on Chronic Myeloid Leukemia (CML) prevalence are scarce. Here we provide an estimation of the prevalence of CML in France for the year 2014 using French national health insurance data.

Methods

We selected patients claiming reimbursement for tyrosine kinase inhibitors (TKI) or with hospital discharge diagnoses for CML, BCR/ABL‐positive or with full reimbursement of health care expenses for myeloid leukemia. We built an algorithm which we validated on a random sample of 100 potential CML patients by comparing the results obtained using the algorithm and the opinion of two hematologists who reviewed the patient demographics and sequence of care abstracted from claims data (internal validity). For external validity, we compared the number of incident CML patients identified using the algorithm with those recorded in French population‐based cancer registries in departments covered by such a registry.

Results

We identified 10 789 prevalent CML patients in 2014, corresponding to a crude prevalence rate of 16.3 per 100 000 inhabitants [95% confidence interval (CI) 16.0‐16.6]: 18.5 in men [18.0‐19.0] and 14.2 in women [13.8‐14.6]. The crude CML prevalence was less than 1.6 per 100 000 [1.2‐2.0] under age 20, increasing to a maximum of 48.2 [45.4‐51.2) at ages 75‐79. It varied from 10.2 to 23.8 per 100 000 across French departments. The algorithm showed high internal and external validity. Concordance rate between the algorithm and the hematologists was 96%, and the numbers of incident CML patients identified using the algorithm and the registries were 162 and 150, respectively.

Conclusion

We built and validated an algorithm to identify CML patients in administrative healthcare databases. In addition to prevalence estimation, the algorithm could be used for future economic evaluations or pharmaco‐epidemiological studies in this population.

How I treat chronic myeloid leukemia in children and adolescents

Evidence-based recommendations have been established for treatment of chronic myeloid leukemia (CML) in adults treated with tyrosine kinase inhibitors (TKIs), but the rarity of this leukemia in children and adolescents makes it challenging to develop similar recommendations in pediatrics. In addition to imatinib, which was approved for pediatric CML in 2003, the second-generation TKIs dasatinib and nilotinib were recently approved for use in children, expanding the therapeutic options and pushing allogeneic stem cell transplantation to a third-line treatment of most pediatric cases. Yet, without sufficient data on efficacy and safety specific to pediatric patients, the selection of a TKI continues to rely on clinical experience in adults. Here, we present 4 case scenarios highlighting common yet challenging issues encountered in the treatment of pediatric CML (suboptimal response, poor treatment adherence, growth retardation, and presentation in advanced phases). Limited experience with very young children, the transition of teenagers to adult medicine, and the goal of achieving treatment-free remission for this rare leukemia are additional significant obstacles that require further clinical investigation through international collaboration.

Impact of second decline rate of BCR-ABL1 transcript on clinical outcome of chronic phase chronic myeloid leukemia patients on imatinib first-line

Early molecular response has been associated with clinical outcome in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors. The BCR-ABL1 transcript rate decline from baseline to 3 months has been demonstrated to be more predictive than a single BCR-ABL1 level at 3 months (M3). However, it cannot be used routinely because ABL1, as an internal gene control, is not reliable for BCR-ABL1 quantification above 10%. This study aimed to compare clinical outcome and molecular response of chronic phase CML patients, depending on the percentage of BCR-ABL1 transcript decrease from month 3 to month 6 using ABL1 as an internal control gene. Two hundred sixteen chronic phase CML patients treated with imatinib 400 mg for whom M3 and month 6 molecular data were available were included in the study. Associations with event-free (EFS), failure-free (FFS), progression-free (PFS), and overall survivals (OS) molecular response 4 log and 4.5 log were assessed. The percentage of BCR-ABL1 decline from month 3 to month 6 was significantly linked to the EFS and the FFS (p < 0.001). A common cut-off of 67% of decline predicted the better risk of event. Patients with a decrease below 67% have worse EFS and FFS as compared to those having a higher decrease (p < 0.001). The impact was confirmed by multivariate analysis. Since the slope between diagnosis and 3 months cannot be reliable using ABL1 as an internal gene control, the second decline rate of BCR-ABL1 transcript between month 3 and month 6 could efficiently identify patients at higher risk of event.