Deep molecular response in chronic myeloid leukemia: the new goal of therapy?

Analytical validation of the DropXpert S6 system for diagnosis of chronic myelocytic leukemia

Digital PCR is a powerful method for absolute nucleic acid quantification and is widely used in the absolute quantification of viral copy numbers, tumor marker detection, and prenatal diagnosis. However, for most of the existing droplet-based dPCR systems, the droplet generation, PCR reaction, and droplet detection are performed separately using different instruments. Making digital PCR both easy to use and practical by integrating the qPCR workflow into a superior all-in-one walkaway solution is one of the core ideas. A new innovative and integrated digital droplet PCR platform was developed that utilizes cutting-edge microfluidics to integrate dPCR workflows onto a single consumable chip. This makes previously complex workflows fast and simple; the whole process of droplet generation, PCR amplification, and droplet detection is completed on one chip, which meets the clinical requirement of "sample in, result out". It provides high multiplexing capabilities and strong sensitivity while all measurements were within the 95% confidence interval. This study is the first validation of the DropXpert S6 system and focuses primarily on verifying its reliability, repeatability, and consistency. In addition, the accuracy, detection limit, linearity, and precision of the system were evaluated after sample collection. Among them, the accuracy assessment by calculating the absolute bias of each target gene yielded a range from -0.1 to 0.08, all within ±0.5 logarithmic orders of magnitude; the LOB for the assay was set at 0, and the LoD value calculated using probit curves is MR4.7 (0.002%); the linearity evaluation showed that the R2 value of the BCR-ABL was 0.9996, and the R2 value of the ABL metrics calculated using the ERM standard was 0.9999; and the precision evaluation showed that all samples had a CV of less than 4% for intra-day, inter-day, and inter-instrument variation. The CV of inter-batch variation was less than 7%. The total CV was less than 5%. The results of the study demonstrate that dd-PCR can be applied to molecular detection and the clinical evaluation of CML patients and provide more precise personal treatment guidance, and its reproducibility predicts the future development of a wide range of clinical applications.

Chronic myeloid leukaemia: Biology and therapy

Chronic myeloid leukaemia (CML) is caused by BCR::ABL1. Tyrosine kinase-inhibitors (TKIs) are the initial therapy. Several organizations have reported milestones to evaluate response to initial TKI-therapy and suggest when a change of TKI should be considered. Achieving treatment-free remission (TFR) is increasingly recognized as the optimal therapy goal. Which TKI is the best initial therapy for which persons and what depth and duration of molecular remission is needed to achieve TFR are controversial. In this review we discuss these issues and suggest future research directions.

Flow Cytometric Assessment of CD26-Positive Leukemic Stem Cells: A Rapid and Valuable Tool in the Diagnosis and Follow-Up of Chronic Myeloid Leukemia

Context Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm. Recent studies have suggested that CD26-positive leukemic stem cells (LSCs) circulating in peripheral blood are specific for CML. Objective This study was undertaken to determine the proportion of CD26-positive LSCs at diagnosis and its change during tyrosine kinase inhibitor therapy. Design This prospective study was conducted on 43 cases of CML at diagnosis. For flow cytometry, peripheral blood cells were stained with CD45, CD34, CD38, CD3, and CD26. A sequential gating strategy with CD45/SSC (side scatter), CD34/SSC, and CD34/CD38 was applied to identify CD45+/34+/38- populations, from which CD26-positive stem cells were identified and compared with controls. Data analysis was done with Kaluza software. Results All patients diagnosed with CML were detected with CD26-positive LSCs. The median percentage of CD26-positive CML LSCs was 0.02 with a range of 0.001 to 1.77. None of the control samples showed CD26 positivity. The percentage and absolute count of CD26-positive CML LSCs were reduced after six months of tyrosine kinase therapy in patients with complete hematological remission. Conclusion Flow cytometric analysis of circulating CD26-positive CML LSCs is a non-invasive, rapid, and useful tool in the diagnosis and follow-up of CML.

The Success of Treatment Free Remission in Chronic Myeloid Leukaemia in Clinical Practice: A Single-Centre Retrospective Experience from South Africa

Introduction

Chronic myeloid leukaemia (CML) management has evolved from a disease once considered to be incurable just over 2 decades ago to that of one of a "functional cure" as defined by the sustained molecular response on stopping tyrosine kinase inhibitor(TKI) therapy. The next goal of CML management has been treatment-free remission (TFR). The past 4 years have seen much international data on TFR attempts in CML in clinical practice. However, Africa as a continent has lagged behind the rest of the world, in keeping up with the latest trends in CML management, and so this study aims to address this gap by assessing the outcome of TFR in CML in a single centre in South Africa (SA).

Methods

We conducted a retrospective cohort study in 12 CML patients in the chronic phase to assess the success of TKI discontinuation. The patients were treated in King Edward VIII Hospital (KEH), a tertiary, academic hospital in KwaZulu-Natal, South Africa, and the study period was from June 2020 to May 2022. Patients included had to have been on TKI therapy for a minimum of 5 years and achieved a deep molecular response (DMR) for a minimum period of 3 years.

Results

The overall TFR cohort showed a success rate of 75% at a median follow-up of 12 months. All patients who failed TFR, defined as a loss of major molecular remission (MMR), failed within 6 months of stopping TKI therapy. All patients who failed TFR regained DMR after retreatment with TKI, with no disease progression reported. The only factor influencing the success of TFR was the total period of TKI therapy.

Conclusion

Despite our study having a small cohort of patients, this study demonstrated that TFR in CML is an attainable goal, even in a resource-limited setting.

Molecular BCR::ABL1 Quantification and ABL1 Mutation Detection as Essential Tools for the Clinical Management of Chronic Myeloid Leukemia Patients: Results from a Brazilian Single-Center Study

Chronic myeloid leukemia (CML) is a well-characterized oncological disease in which virtually all patients possess a translocation (9;22) that generates the tyrosine kinase BCR::ABL1 protein. This translocation represents one of the milestones in molecular oncology in terms of both diagnostic and prognostic evaluations. The molecular detection of the BCR::ABL1 transcription is a required factor for CML diagnosis, and its molecular quantification is essential for assessing treatment options and clinical approaches. In the CML molecular context, point mutations on the ABL1 gene are also a challenge for clinical guidelines because several mutations are responsible for tyrosine kinase inhibitor resistance, indicating that a change may be necessary in the treatment protocol. So far, the European LeukemiaNet and the National Comprehensive Cancer Network (NCCN) have presented international guidelines on CML molecular approaches, especially those related to BCR::ABL1 expression. In this study, we show almost three years' worth of data regarding the clinical treatment of CML patients at the Erasto Gaertner Hospital, Curitiba, Brazil. These data primarily comprise 155 patients and 532 clinical samples. BCR::ABL1 quantification by a duplex-one-step RT-qPCR and ABL1 mutations detection were conducted. Furthermore, digital PCR for both BCR::ABL1 expression and ABL1 mutations were conducted in a sub-cohort. This manuscript describes and discusses the clinical importance and relevance of molecular biology testing in Brazilian CML patients, demonstrating its cost-effectiveness.

Outcomes of adolescents and young adults with chronic-phase chronic myeloid leukaemia treated with tyrosine kinase inhibitors

INTRODUCTION

Few studies have reported the outcomes of adolescents and young adults (AYAs) with chronic-phase chronic myeloid leukaemia (CML-CP) on tyrosine kinase inhibitors (TKIs).

MATERIALS AND METHODS

We retrospectively analysed the clinical features, treatment response, and long-term outcomes of 42 AYA patients, in comparison to older patients. The initial therapies of AYA patients between 2001 and 2016 included imatinib (n = 24), dasatinib (n = 13) and nilotinib (n = 5).

RESULTS

In AYA patients, the peripheral blood (PB) white blood cell count and percentage of blasts at the diagnosis were significantly higher, haemoglobin levels were lower and the spleen size was larger. The major molecular response (MMR), event-free survival (EFS) and overall survival (OS) rates were comparable. A sub-analysis comparing imatinib to second-generation TKIs as the initial therapy also showed that their prognosis was comparable.

DISCUSSION

In conclusion, the tumour burden at the diagnosis of CML-CP is higher in AYA patients; however, their prognosis was not worse in comparison to older patients treated with TKIs. KEY MESSAGESFew studies have reported the outcomes of adolescents and young adults (AYAs) with chronic-phase chronic myeloid leukaemia (CML-CP) on tyrosine kinase inhibitors (TKIs). This study showed the tumour burden at the diagnosis of CML-CP is higher in AYA pa tients; however, their prognosis was not worse in comparison to older patients treated with TKIs. Understanding the biological and non-biological features of AYA patients with CML-CP on TKI therapy is essential for better management and to improve the outcomes.

A multicenter real-world evidence study in the Swiss treatment landscape of chronic myeloid leukemia

Background

The real-world experience of Swiss chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs) is largely unknown, in particular with regard to achievement of response per European Leukemia Net (ELN) criteria and adherence to ELN recommendations.

Methods

This was a retrospective, non-interventional, multicenter chart review of patients with newly diagnosed CML who had received first-line TKI and were solely treated with TKIs between 2010 and 2015, with a minimum follow-up of 18 months, at six Swiss hospitals. Effectiveness was evaluated according to ELN 2013 milestone achievements at 3, 6, 12 and 18 months, and at last follow-up.

Results

Data from 63 patients (56% men; median age at diagnosis 55 years) were collected (first-line imatinib [n = 27], nilotinib [n = 27], dasatinib [n = 8], or ponatinib [n = 1]). TKI switches (49 times) and dosing changes (165 times) due to intolerance or insufficient response were frequent. Compared with patients receiving first-line imatinib, a higher proportion of patients receiving first-line nilotinib or dasatinib achieved optimal response at all timepoints, irrespective of subsequent TKI therapy, and a higher proportion of patients treated with first-line nilotinib and dasatinib reached deep molecular response (BCR-ABL1^IS ≤ 0.01%) at 18 months (42 and 38%, respectively, versus 27%). Patients who received nilotinib or dasatinib switched therapies less frequently than patients treated with imatinib, irrespective of subsequent TKI therapy.

Conclusions

Although patient numbers were small, this real-world evidence study with patients with CML confirms that ELN guidelines are generally implemented in Swiss clinical practice, with a large proportion of patients achieving ELN 2013 milestones. While TKI use involved all inhibitors approved at the time of the study, an unexpectedly high number of TKI therapy switches suggests a clear difference in TKI use between registration trials and clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10241-y.

Early dynamics of chronic myeloid leukemia on nilotinib predicts deep molecular response

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by the BCR-ABL1 tyrosine kinase. Although ABL1-specific tyrosine kinase inhibitors (TKIs) including nilotinib have dramatically improved the prognosis of patients with CML, the TKI efficacy depends on the individual patient. In this work, we found that the patients with different nilotinib responses can be classified by using the estimated parameters of our simple dynamical model with two common laboratory findings. Furthermore, our proposed method identified patients who failed to achieve a treatment goal with high fidelity according to the data collected only at three initial time points during nilotinib therapy. Since our model relies on the general properties of TKI response, our framework would be applicable to CML patients who receive frontline nilotinib or other TKIs.

Cross-Domain Text Mining to Predict Adverse Events from Tyrosine Kinase Inhibitors for Chronic Myeloid Leukemia

Tyrosine kinase inhibitors (TKIs) are prescribed for chronic myeloid leukemia (CML) and some other cancers. The objective was to predict and rank TKI-related adverse events (AEs), including under-reported or preclinical AEs, using novel text mining. First, k-means clustering of 2575 clinical CML TKI abstracts separated TKIs by significant (p < 0.05) AE type: gastrointestinal (bosutinib); edema (imatinib); pulmonary (dasatinib); diabetes (nilotinib); cardiovascular (ponatinib). Next, we propose a novel cross-domain text mining method utilizing a knowledge graph, link prediction, and hub node network analysis to predict new relationships. Cross-domain text mining of 30+ million articles via SemNet predicted and ranked known and novel TKI AEs. Three physiology-based tiers were formed using unsupervised rank aggregation feature importance. Tier 1 ranked in the top 1%: hematology (anemia, neutropenia, thrombocytopenia, hypocellular marrow); glucose (diabetes, insulin resistance, metabolic syndrome); iron (deficiency, overload, metabolism), cardiovascular (hypertension, heart failure, vascular dilation); thyroid (hypothyroidism, hyperthyroidism, parathyroid). Tier 2 ranked in the top 5%: inflammation (chronic inflammatory disorder, autoimmune, periodontitis); kidney (glomerulonephritis, glomerulopathy, toxic nephropathy). Tier 3 ranked in the top 10%: gastrointestinal (bowel regulation, hepatitis, pancreatitis); neuromuscular (autonomia, neuropathy, muscle pain); others (secondary cancers, vitamin deficiency, edema). Results suggest proactive TKI patient AE surveillance levels: regular surveillance for tier 1, infrequent surveillance for tier 2, and symptom-based surveillance for tier 3.

Defining disease modification in myelofibrosis in the era of targeted therapy

The development of targeted therapies for the treatment of myelofibrosis highlights a unique issue in a field that has historically relied on symptom relief, rather than survival benefit or modification of disease course, as key response criteria. There is, therefore, a need to understand what constitutes disease modification of myelofibrosis to advance appropriate drug development and therapeutic pathways. Here, the authors discuss recent clinical trial data of agents in development and dissect the potential for novel end points to act as disease modifying parameters. Using the rationale garnered from latest clinical and scientific evidence, the authors propose a definition of disease modification in myelofibrosis. With improved overall survival a critical outcome, alongside the normalization of hematopoiesis and improvement in bone marrow fibrosis, there will be an increasing need for surrogate measures of survival for use in the early stages of trials. As such, the design of future clinical trials will require re-evaluation and updating to incorporate informative parameters and end points with standardized definitions and methodologies.

Integrated Genomic Analysis Identifies ANKRD36 Gene as a Novel and Common Biomarker of Disease Progression in Chronic Myeloid Leukemia

Simple Summary

Chronic myeloid leukemia is a type of blood cancer that is regarded as a success story in determining the exact biological origin, pathogenesis and development of a molecularly targeted (mutation-specific) therapy that has led to successful treatment of this fatal cancer. It is caused by the BCR-ABL fusion gene, which is formed from the translocation between chromosomes 9 and 22. Anti-BCR-ABL drugs, known as tyrosine kinase inhibitors (TKIs), have led to long-term remissions in more than 80% of CML patients and even cure in about one-third of patients. Nevertheless, many patients face drug resistance, and disease progression occurs in about 30% of CML patients, leading to morbidities and mortality. Unfortunately, no biomarkers of CML progression are available due to a poor understanding of the mechanism of progression. Therefore, finding reliable molecular biomarkers of CML progression is one of the most attractive research areas in 21st-century cancer research. In this study, we report novel genomic variants exclusively found in all our advanced-phase CML patients. This study will help in identifying CML patients at risk of disease progression and timely therapeutic interventions to avoid or at least delay fatal disease progression in this cancer.

Abstract

Background: Chronic myeloid leukemia (CML) is initiated in bone marrow due to chromosomal translocation t(9;22) leading to fusion oncogene BCR-ABL. Targeting BCR-ABL by tyrosine kinase inhibitors (TKIs) has changed fatal CML into an almost curable disease. Despite that, TKIs lose their effectiveness due to disease progression. Unfortunately, the mechanism of CML progression is poorly understood and common biomarkers for CML progression are unavailable. This study was conducted to find novel biomarkers of CML progression by employing whole-exome sequencing (WES). Materials and Methods: WES of accelerated phase (AP) and blast crisis (BC) CML patients was carried out, with chronic-phase CML (CP-CML) patients as control. After DNA library preparation and exome enrichment, clustering and sequencing were carried out using Illumina platforms. Statistical analysis was carried out using SAS/STAT software version 9.4, and R package was employed to find mutations shared exclusively by all AP-/BC-CML patients. Confirmation of mutations was carried out using Sanger sequencing and protein structure modeling using I-TASSER followed by mutant generation and visualization using PyMOL. Results: Three novel genes (ANKRD36, ANKRD36B and PRSS3) were mutated exclusively in all AP-/BC-CML patients. Only ANKRD36 gene mutations (c.1183_1184 delGC and c.1187_1185 dupTT) were confirmed by Sanger sequencing. Protein modeling studies showed that mutations induce structural changes in ANKRD36 protein. Conclusions: Our studies show that ANKRD36 is a potential common biomarker and drug target of early CML progression. ANKRD36 is yet uncharacterized in humans. It has the highest expression in bone marrow, specifically myeloid cells. We recommend carrying out further studies to explore the role of ANKRD36 in the biology and progression of CML.

Ultra-deep sequencing mutation analysis of the BCR/ABL1 kinase domain in newly diagnosed chronic myeloid leukemia patients

Ultra-deep sequencing detects low-frequency genetic mutations with high sensitivity. We used this approach to prospectively examine mutations in the BCR/ABL1 tyrosine kinase from patients with newly diagnosed, chronic-phase chronic myeloid leukemia (CML) treated with the tyrosine kinase inhibitor nilotinib. Between May 2013 and November 2014, 50 patients from 18 institutions were enrolled in the study. We screened 103 somatic mutations and found that mutations in the P-loop domain were the most frequent (173/454 mutations in the P-loop) and noted the presence of the V299 L mutation (dasatinib-resistant/nilotinib-sensitive) in 98 % of patients (49/50). No patients had Y253H, E255 V, or F359 V/C/I mutations, which would recommend dasatinib rather than nilotinib treatment. The S417Y mutation was associated with lower achievement of a major molecular response (MMR) at 6 months, and the V371A mutation was associated with reduced MMR and MR^4.5 durations (MMR for 2 years: 100 % for no mutation vs. 75 % for mutation, P=0.039; MR^4.5 for 15 months: 94.1 % vs. 25 %, P=0.002). Patients with known nilotinib-resistant mutations had lower rates of MR^4.5 achievement. In conclusion, ultra-deep sequencing is a sensitive method for genetic-based treatment decisions. Based on the results of these mutational analyses, nilotinib treatment is a promising option for Korean patients with CML.

Evaluation of the outcomes in patients with chronic myeloid leukemia treated with imatinib in 18-year follow-up

The objective of this paper is to examine the effects of Imatinib on patients who are at the chronic phase of chronic myeloid leukemia (CML). Method: Totally, 79 patients with CML who received the treatment between 2003 and 2020 entered the study. The patients were evaluated in terms of molecular response rate and overall survival (OS). Results: About 75.9% of patients achieved deep molecular response in mean follow-up of 89.92 months. The OS rate was about 91.2%. Conclusion: There was no considerable cumulative toxicity with Imatinib long-term use. A high percent of patients had a deep molecular response.

Detection of mutations in CML patients resistant to tyrosine kinase inhibitor: imatinib mesylate therapy

Imatinib mesylate, a tyrosine kinase inhibitor, is the first choice in chronic myeloid leukemia treatment. However, resistance to imatinib may develop with time and in some cases, patients may not respond at all to imatinib. Progressive resistance to imatinib therapy is often due to mutations in the BCR/ABL region. Within the scope of our study 124 patients were evaluated via pyrosequencing between 2015 and 2020. In this regard, 32 patients who have a partial response and have no response to imatinib therapy were included in the study. In addition, next-generation sequencing (NGS) analysis was performed on 15 patients who were resistant to imatinib treatment according to the molecular follow-up reports. With pyrosequencing, 5 cases out of a total of 124 were found to be positive. This means that approximately 4.03% of the proportion is positive. But when we examined only 32 patients who have a partial response and have no response to imatinib therapy this rate is rising 15.6%. NGS analysis was performed with 15 patients who have no mutation with pyrosequencing of 32 patients and VUS (Variant of Uncertain Significance) mutation was detected in one. In this study, our aim was to determine the mutations of the BCR/ABL and to evaluate the mutations by NGS and pyrosequencing. Our study is important in terms of comparing the pyrosequencing with NGS mutation rates, drawing attention to the clinical importance of log reduction.

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.

Increased Expression of TIGIT/CD57 in Peripheral Blood/Bone Marrow NK Cells in Patients with Chronic Myeloid Leukemia

The antitumor activity of NK cells in patients with chronic myeloid leukemia (CML) is inhibited by the leukemia microenvironment. Recent studies have identified that the expression of TIGIT, CD57, and KLRG1 is related to the function, maturation, and antitumor capabilities of NK cells. However, the characteristics of the expression of these genes in the peripheral blood (PB) and bone marrow (BM) from patients with CML remain unknown. In this study, we used multicolor flow cytometry to assay the quantity and phenotypic changes of NK cells in PB and BM from de novo CML (DN-CML) and CML patients acquiring molecular response (MR-CML). We found that the expression of TIGIT, which inhibits NK cell function, is increased on CD56⁺ and CD56^dim NK cells in DN-CML PB compared with those in healthy individuals (HIs), and it is restored to normal in patients who achieve MR. We also found that the expression of CD57 on NK cells was approximately the same level in PB and BM from DN-CML patients, while decreased CD57 expression was found on CD56⁺ and CD56^dim NK cells in HI BM compared with PB. Additionally, those two subsets were significantly increased in DN-CML BM compared to HI BM. The expression of CD57 correlates with replicative senescence and maturity for human NK cells; therefore, the increase in TIGIT on PB NK cells together with an increase in CD57 on BM NK cells may explain the subdued NK cell antileukemia capacity and proliferative ability in DN-CML patients. These results indicate that reversing the immune suppression of PB NK cells by blocking TIGIT while improving the proliferation of BM NK cells via targeting CD57 may be more effective in removing tumor cells.

Is There a Role for Dose Modification of TKI Therapy in CML?

Purpose of Review

For patients with chronic phase chronic myeloid leukemia (CP-CML), there is an increasing focus on personalization of therapy with dose modifications of tyrosine kinase inhibitors (TKIs) to reduce side effects and maintain efficacy. Dose reductions are also being considered in clinical trials prior to treatment-free remission (TFR) attempts.

Recent Findings

Recent retrospective analyses of large clinical trials show that dose modification/reduction is safe. Efficacy is generally maintained and side effects are improved. Clinical trials such as DESTINY have demonstrated that dose reduction is safe for patients in deep molecular remission and may be considered prior to a TFR attempt.

Summary

Dose modifications are widely used to prevent and manage the toxicities of TKIs. With adequate monitoring, dose optimization is safe, reduces side effects, and improves quality-of-life for patients. Clinical trials of dose optimization are currently recruiting across all approved TKIs and will lead to further personalization of therapy for CP-CML patients in the future.

Relationship between molecular response and quality of life with bosutinib or imatinib for chronic myeloid leukemia

Patients with newly diagnosed chronic phase chronic myeloid leukemia (CP CML) can be effectively treated with tyrosine kinase inhibitors (TKIs) and achieve a lifespan similar to the general population. The success of TKIs, however, requires long-term and sometimes lifelong treatment; thus, patient-assessed health-related quality of life (HRQoL) has become an increasingly important parameter for treatment selection. Bosutinib is a TKI approved for CP CML in newly diagnosed adults and in those resistant or intolerant to prior therapy. In the Bosutinib Trial in First-Line Chronic Myelogenous Leukemia Treatment (BFORE), bosutinib demonstrated a significantly higher major molecular response rate compared with imatinib, with maintenance of HRQoL (measured by the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu) questionnaire), after 12 months of first-line treatment. We examined relationships between molecular response (MR) and HRQoL. MR values were represented by a log-reduction scale (MRLR; a continuous variable). A repeated-measures longitudinal model was used to estimate the relationships between MRLR as a predictor and each FACT-Leu domain as an outcome. Effect sizes were calculated to determine strength of effects and allow comparisons across domains. The majority of FACT-Leu domains (with the exception of social well-being and physical well-being) demonstrated a significant relationship with MRLR (p < 0.05). Our results showed variable impact of clinical improvement on different dimensions of HRQoL. For patients who achieved MR⁵, emotional well-being and leukemia-specific domains showed the greatest improvement, with medium differences in effect sizes, whereas social well-being and physical well-being had the weakest relationship with MR.

Use of Droplet Digital Polymerase Chain Reaction for Detecting Minimal Residual Disease: A Prospective Multi-Institutional Study

BACKGROUND/AIM

Droplet digital polymerase chain reaction (ddPCR) is an exact method of measuring nucleic acids. The aim of this prospective study was to evaluate minimal residual disease (MRD) using ddPCR in chronic myeloid leukemia (CML) patients.

PATIENTS AND METHODS

Between May 2013 and November 2014, CML patients treated with nilotinib were enrolled in our study. BCR/ABL1 transcripts levels were evaluated using ddPCR at the first time of complete molecular response (CMR). We enrolled 15 patients from 7 Institutions. The treatment period and median follow-up period were 45 months and 47 months, respectively.

RESULTS

Patients with a high level of BCR/ABL1 transcript had a greater tendency to lose the CMR during the follow-up period (p=0.095). In addition, patients with a low level of BCR/ABL1 transcript showed a longer duration of CMR compared to those with a high level (p=0.032).

CONCLUSION

We found that ddPCR is a sensitive method for detecting MRD and that MRD could affect the duration of the treatment response.

Assessing Measurable Residual Disease in Chronic Myeloid Leukemia. BCR-ABL1 IS in the Avant-Garde of Molecular Hematology

Chronic myelogenous leukemia (CML) is a malignancy of the myeloid cell lineage characterized by a recurrent chromosomal abnormality: the Philadelphia chromosome, which results from the reciprocal translocation of the chromosomes 9 and 22. The Philadelphia chromosome contains a fusion gene called BCR-ABL1. The BCR-ABL1 codes for an aberrantly functioning tyrosine kinase that drives the malignant proliferation of the founding clone. The advent of tyrosine kinase inhibitors (TKI) represents a landmark in the treatment of CML, that has led to tremendous improvement in the remission and survival rates. Since the introduction of imatinib, the first TKI, several other TKI have been approved that further broadened the arsenal against CML. Patients treated with TKIs require sensitive monitoring of BCR-ABL1 transcripts with quantitative real-time polymerase chain reaction (qRT-PCT), which has become an essential part of managing patients with CML. In this review, we discuss the importance of the BCR-ABL1 assay, and we highlight the growing importance of BCR-ABL1 dynamics. We also introduce a mathematical correction for the BCR-ABL1 assay that could help homogenizing the use of the ABL1 as a control gene. Finally, we discuss the growing body of evidence concerning treatment-free remission. Along with the continuous improvement in the therapeutic arsenal against CML, the molecular monitoring of CML represents the avant-garde in the struggle to make CML a curable disease.

Treatment patterns and deep molecular response in chronic phase - chronic myeloid leukemia patients treated with second-line nilotinib or dasatinib: a multi-country retrospective chart review study

Achievement of MR4.5 (BCR-ABL1 ≤ 0.0032% on international scale) is an important goal of tyrosine kinase inhibitor (TKI) treatment for patients with chronic myeloid leukemia (CML). This study describes treatment patterns by region and assesses time to achieve MR4.5 in patients with CML - chronic phase (CP) treated with second-line nilotinib or dasatinib in 10 countries. A multivariate Cox proportional hazards model was used to assess time to MR4.5 for nilotinib versus dasatinib. The model accounted for the competing-risk event of TKI resistance, included random effects for country clustering, and was adjusted for baseline covariates. The study included 280 patients treated with either nilotinib (N = 135 [48%]) or dasatinib (N = 145 [52%]) as second-line TKI with median treatment durations of 19.1 and 18.7 months, respectively. Nilotinib was observed to be better in achieving MR4.5 than dasatinib (adjusted hazard ratio = 1.37, 95% CI [1.11, 1.69]) suggesting second-line nilotinib may perform better in achieving MR4.5 than dasatinib.

HMGCLL1 is a predictive biomarker for deep molecular response to imatinib therapy in chronic myeloid leukemia

Achieving a deep molecular response (DMR) to tyrosine kinase inhibitor (TKI) therapy for chronic myeloid leukemia (CML) remains challenging and at present, there is no biomarker to predict DMR in this setting. Herein, we report that an HMGCLL1 genetic variant located in 6p12.1 can be used as a predictive genetic biomarker for intrinsic sensitivity to imatinib (IM) therapy. We measured DMR rate according to HMGCLL1 variant in a discovery set of CML patients (n = 201) and successfully replicated it in a validation set (n = 270). We also investigated the functional relevance of HMGCLL1 blockade with respect to response to TKI therapy and showed that small interfering RNA mediated blockade of HMGCLL1 isoform 3 results in significant decrease in viability of BCR-ABL1-positive cells including K562, CML-T1 or BaF3 cell lines with or without ABL1 kinase domain mutations such as T315I mutation. Decreased cell viability was also demonstrated in murine CML stem cells and human hematopoietic progenitor cells. RNA sequencing showed that blockade of HMGCLL1 was associated with G0/G1 arrest and the cell cycle. In summary, the HMGCLL1 gene polymorphism is a novel genetic biomarker for intrinsic sensitivity to IM therapy in CML patients that predicts DMR in this setting.

Feasibility of treatment discontinuation in chronic myeloid leukemia in clinical practice: results from a nationwide series of 236 patients

Over half of chronic myeloid leukemia (CML) patients in deep molecular response do not lose the major molecular response (MMR) after stopping treatment with tyrosine kinase inhibitors (TKI). This strategy is safe in clinical trials, but its applicability in the real-life setting remains unsettled. We describe the outcomes after TKI discontinuation in a nationwide series of 236 CML patients. Median follow-up from treatment discontinuation was 21.5 months and 5 patients died from CML-unrelated causes. TKI therapy was reinitiated due to MMR loss (n = 52), increase ≥ 1 log in BCR-ABL transcript level without losing MMR (n = 12), patient preference (n = 2), and withdrawal syndrome (n = 1). Treatment-free remission rate at 4 years was 64% (95% confidence interval, CI: 55%–72%). Cumulative incidence of molecular recurrence at 3 years was 33% (95% CI: 26%–38%). TKI treatment for < 5 years and MR4.5 duration shorter than 4 years were both associated with higher incidence of molecular recurrence. No patient had disease progression. Response status at last control was: MR4.5 (n = 196), MR4 (n = 15), MMR (n = 14), complete cytogenetic response (n = 10), and other (n = 1). A significant increase in Hb and cholesterol levels was observed after imatinib withdrawal. Our results demonstrate that TKI treatment discontinuation is feasible in real-life clinical practice.

External quality assessment of p210 BCR-ABL1 transcript quantification by RT-qPCR: Findings and recommendations

INTRODUCTION

External quality assessment (EQA) is an essential tool for quality assurance of analytical testing processes of p210 BCR-ABL1 transcripts by RT-qPCR. As an EQA provider, the National Center for Clinical Laboratories organized an EQA scheme of p210 BCR-ABL1 testing in China for the first time to identify existing problems and ensure the reliability of p210 BCR-ABL1 testing.

METHODS

Using armored RNA technology, we first constructed pACYC-MS2-p210 and CG recombinant plasmids and expressed p210 and CG armored RNAs, with packaging segments of p210 BCR-ABL1 fusion gene (FG) and four common control gene (CG) transcripts. Using these armored RNAs, we prepared lyophilized p210 quality control (QC) sample panels and evaluated detection performance of participating laboratories in China.

RESULTS

Of the 66 participating laboratories, great variation was found with coefficient of variation (CV%) of raw p210 BCR-ABL1 results basically ranging from 60.0% to 100.0%. In 24 International Scale (IS) laboratories, the CV% of results decreased from 82.4% to 61.6%, and the percentage of laboratories within 2-, 3-, and 5-fold of the median values increased from 78.2%, 87.0%, and 92.1% to 80.1%, 89.4%, and 97.2%, respectively, after conversion with a laboratory-specific conversion factor (CF); however, poorly converted results were also observed in laboratories resulting from changed components of RT-qPCR procedures. False-negative and false-positive results were also found in the EQA.

CONCLUSIONS

Various problems were found for p210 BCR-ABL1 detection in the EQA. By solving the existing problems, the performance of p210 BCR-ABL1 detection can be improved, ensuring robust laboratory diagnostic capacities in China.

Single-Molecule Sequencing Reveals Patterns of Preexisting Drug Resistance That Suggest Treatment Strategies in Philadelphia-Positive Leukemias

Purpose: Sequential treatment with targeted therapies can result in complex combinations of resistance mutations in drug targets. This mutational complexity has spurred the development of pan-target inhibitors, i.e., therapies for which no single target mutation can cause resistance. Because the propensity for on- versus off-target resistance varies across cancer types, a deeper understanding of the mutational burden in drug targets could rationalize treatment outcomes and prioritize pan-target inhibitors for indications where on-target mutations are most likely.Experimental Design: To measure and model the mutational landscape of a drug target at high resolution, we integrated single-molecule Duplex Sequencing of the ABL1 gene in Philadelphia-positive (Ph⁺) leukemias with computational simulations.Results: A combination of drug target mutational burden and tumor-initiating cell fraction is sufficient to predict that most patients with chronic myeloid leukemia are unlikely to harbor ABL1 resistance mutations at the time of diagnosis, rationalizing the exceptional success of targeted therapy in this setting. In contrast, our analysis predicts that many patients with Ph⁺ acute lymphoblastic leukemia (Ph⁺ ALL) harbor multiple preexisting resistant cells with single mutants. The emergence of compound mutations can be traced to initial use of an ABL1 inhibitor that is susceptible to resistance from single point mutations.Conclusions: These results argue that early use of therapies that achieve pan-inhibition of ABL1 resistance mutants might improve outcomes in Ph⁺ ALL. Our findings show how a deep understanding of the mutational burden in drug targets can be quantitatively coupled to phenotypic heterogeneity to rationalize clinical phenomena. Clin Cancer Res; 24(21); 5321-34. ©2018 AACR.

BCR-ABL1 genomic DNA PCR response kinetics during first-line imatinib treatment of chronic myeloid leukemia

Accurate quantification of minimal residual disease (MRD) during treatment of chronic myeloid leukemia (CML) guides clinical decisions. The conventional MRD method, RQ-PCR for BCR-ABL1 mRNA, reflects a composite of the number of circulating leukemic cells and the BCR-ABL1 transcripts per cell. BCR-ABL1 genomic DNA only reflects leukemic cell number. We used both methods in parallel to determine the relative contribution of the leukemic cell number to molecular response. BCR-ABL1 DNA PCR and RQ-PCR were monitored up to 24 months in 516 paired samples from 59 newly-diagnosed patients treated with first-line imatinib in the TIDEL-II study. In the first three months of treatment, BCR-ABL1 mRNA values declined more rapidly than DNA. By six months, the two measures aligned closely. The expression of BCR-ABL1 mRNA was normalized to cell number to generate an expression ratio. The expression of e13a2 BCR-ABL1 was lower than that of e14a2 transcripts at multiple time points during treatment. BCR-ABL1 DNA was quantifiable in 48% of samples with undetectable BCR-ABL1 mRNA, resulting in MRD being quantifiable for an additional 5-18 months (median 12 months). These parallel studies show for the first time that the rapid decline in BCR-ABL1 mRNA over the first three months of treatment is due to a reduction in both cell number and transcript level per cell, whereas beyond three months, falling levels of BCR-ABL1 mRNA are proportional to the depletion of leukemic cells.

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

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

When to Stop Tyrosine Kinase Inhibitors for the Treatment of Chronic Myeloid Leukemia

Strict criteria for when to stop tyrosine kinase inhibitor (TKI) therapy in clinical practice are not easily defined without an agreement on what probability of achieving a treatment-free remission (TFR) constitutes a medically acceptable standard and consideration of the potential medical risks of continued TKI therapy and/or patient preferences. Patients in sustained deep molecular response (DMR) have no significant chronic myelogenous leukemia-related risk of progression and death, and thus, safety is of paramount importance. Patients with prior history of advanced disease, additional chromosomal abnormalities (ACA), atypical transcripts, TKI resistance, high Sokal score, or who cannot be relied upon to come for regular molecular monitoring should generally be excluded from TKI cessation in clinical practice. Similarly, stopping TKIs should not be attempted without the availability of standardized BCR-ABL1 testing with a sensitivity of at least MR4.5 and a turnaround time of less than 4 weeks. Prior TKI therapy of 5 years and stable MR4.0 of 2 years or more constitutes reasonable minimal criteria for stopping TKIs with approximately a 50% chance of success. The risk of morbidity with continued TKI therapy and patient preferences need to be considered to determine to what extent these minimal criteria should be exceeded and at what threshold to re-initiate therapy whether on the loss of major molecular response or at a lower molecular endpoint.

Efficacy and safety of nilotinib 300 mg twice daily in patients with chronic myeloid leukemia in chronic phase who are intolerant to prior tyrosine kinase inhibitors: Results from the Phase IIIb ENESTswift study

BACKGROUND

Some patients receiving a tyrosine kinase inhibitor (TKI) for the first-line treatment of chronic phase chronic myeloid leukemia (CML-CP) experience intolerable adverse events. Management strategies include dose adjustments, interrupting or discontinuing therapy, or switching to an alternative TKI.

METHODS

This multicenter, single-arm, Phase IIIb study included CML-CP patients intolerant of, but responsive to, first-line treatment with imatinib or dasatinib. All patients were switched to nilotinib 300 mg bid for up to 24 months. The primary endpoint was achievement of MR4.5 (BCR-ABL transcript level of ≤0.0032% on the International Scale) by 24 months.

RESULTS

Twenty patients were enrolled in the study (16 imatinib-intolerant, 4 dasatinib-intolerant); which was halted early because of low recruitment. After the switch to nilotinib 300 mg bid, MR4.5 at any time point up to month 24 was achieved in 10 of 20 patients (50%) in the full analysis set. Of the non-hematological adverse events associated with intolerance to prior imatinib or dasatinib, 74% resolved within 12 weeks of switching to nilotinib 300 mg bid.

CONCLUSION

Nilotinib 300 mg bid shows minimal cross intolerance in patients with CML-CP who have prior toxicities to other TKIs and can lead to deep molecular responses.

TKI rotation-induced persistent deep molecular response in multi-resistant blast crisis of Ph+ CML

In chronic myeloid leukemia (CML) resistance against one or more BCR-ABL1 tyrosine kinase inhibitors (TKI) remains a clinical challenge. Preclinical data suggest that TKI combinations may overcome resistance. We report on a heavily pre-treated 78 year-old female patient with CML who developed multi-resistant blast crisis with bone marrow fibrosis and a Ph- clone. Treatment with ponatinib resulted in blast cell clearance, decrease in fibrosis, and disappearance of BCR-ABL1, but also in severe thrombocytopenia with bleedings requiring platelet transfusions. We therefore switched from ponatinib to bosutinib. During bosutinib, platelet counts recovered. However, after 6 months, BCR-ABL1 mRNA levels increased to > 1%. Therefore, we ´switched back´ to ponatinib, and this was again followed by disappearance of BCR-ABL1 and a decrease in platelets. During the next 2 years, we applied ponatinib and bosutinib in continuous rotation-cycles and added hydroxyurea in order to suppress all sub-clones and to balance between efficacy and potential side effects following the principle of personalized medicine. With this approach the patient remained in complete molecular response and reached normal blood counts and a normal quality of life without vascular or other side effects. In conclusion, TKI rotation is a novel potent approach to suppress multiple resistant sub-clones and to balance between clinical efficacy and side effects in patients with advanced CML. Clinical trials are now warranted to show that TKI-rotation is in general safe and effective in these patients.

First-line treatment strategies for newly diagnosed chronic myeloid leukemia: a network meta-analysis

OBJECTIVES

With bosutinib proven to be available for frontline treatment, there are currently four frontline treatments as well as an additional strategy with high-dose imatinib for newly diagnosed chronic myeloid leukemia (CML). Due to the lack of direct comparison of high-dose imatinib, dasatinib, nilotinib, and bosutinib, we summarized the evidence to indirectly compare the efficacy among these treatment options.

METHODS

In total, 14 randomized clinical trials including 5,630 patients were analyzed by direct and mixed-treatment comparisons. Outcomes assessed were the following: complete cytogenetic response at 12 months; major molecular response at 12, 24, and 36 months; deep molecular response at 12, 24, 36, and 60 months; early molecular response at 3 months; progression-free survival (PFS); overall survival (OS); and Grade 3 or 4 adverse events (AEs).

RESULTS

The Bayesian network meta-analysis demonstrated that high-dose imatinib was less effective than all new-generation tyrosine kinase inhibitors and had a higher probability of Grade 3 or 4 AEs. For molecular response, 300 mg of nilotinib was likely to be the preferred frontline treatment, as demonstrated by higher response rates and faster, deeper, and longer molecular response. For PFS and OS, there were high likelihoods (79% and 74%, respectively) that 400 mg of nilotinib was the preferred option. For AEs, standard-dose imatinib has the highest probability (65%) of being the most favorable toxicity profile.

CONCLUSION

Considering the efficacy and toxicity profile, it is not recommended to use high-dose imatinib for treatment. This analysis also showed that nilotinib has the highest probability to become the preferred frontline agents for treating CML.

CD36 defines primitive chronic myeloid leukemia cells less responsive to imatinib but vulnerable to antibody-based therapeutic targeting

Tyrosine kinase inhibitors (TKIs) are highly effective for the treatment of chronic myeloid leukemia (CML), but very few patients are cured. The major drawbacks regarding TKIs are their low efficacy in eradicating the leukemic stem cells responsible for disease maintenance and relapse upon drug cessation. Herein, we performed ribonucleic acid sequencing of flow-sorted primitive (CD34⁺CD38^low) and progenitor (CD34⁺ CD38⁺) chronic phase CML cells, and identified transcriptional upregulation of 32 cell surface molecules relative to corresponding normal bone marrow cells. Focusing on novel markers with increased expression on primitive CML cells, we confirmed upregulation of the scavenger receptor CD36 and the leptin receptor by flow cytometry. We also delineate a subpopulation of primitive CML cells expressing CD36 that is less sensitive to imatinib treatment. Using CD36 targeting antibodies, we show that the CD36 positive cells can be targeted and killed by antibody-dependent cellular cytotoxicity. In summary, CD36 defines a subpopulation of primitive CML cells with decreased imatinib sensitivity that can be effectively targeted and killed using an anti-CD36 antibody.

FGFR-TACC gene fusions in human glioma

Chromosomal translocations joining in-frame members of the fibroblast growth factor receptor-transforming acidic coiled-coil gene families (the FGFR-TACC gene fusions) were first discovered in human glioblastoma multiforme (GBM) and later in many other cancer types. Here, we review this rapidly expanding field of research and discuss the unique biological and clinical features conferred to isocitrate dehydrogenase wild-type glioma cells by FGFR-TACC fusions. FGFR-TACC fusions generate powerful oncogenes that combine growth-promoting effects with aneuploidy through the activation of as yet unclear intracellular signaling mechanisms. FGFR-TACC fusions appear to be clonal tumor-initiating events that confer strong sensitivity to FGFR tyrosine kinase inhibitors. Screening assays have recently been reported for the accurate identification of FGFR-TACC fusion variants in human cancer, and early clinical data have shown promising effects in cancer patients harboring FGFR-TACC fusions and treated with FGFR inhibitors. Thus, FGFR-TACC gene fusions provide a "low-hanging fruit" model for the validation of precision medicine paradigms in human GBM.

CML patients with deep molecular responses to TKI have restored immune effectors and decreased PD-1 and immune suppressors

Increased immune suppressors and PD-1 abrogates effector responses in CML patients at diagnosis. Enhanced net effector immune responses and decreased PD-1 and immune suppressors may promote sustained deep molecular response in CML.

Molecular monitoring in chronic myeloid leukemia-how low can you go?

Molecular monitoring of BCR-ABL1 transcripts for patients with chronic myeloid leukemia (CML) is now used to assess response to tyrosine kinase inhibitors (TKIs), including treatment failure that mandates a change of therapy. Therefore, many centers have adopted the molecular technique for measuring BCR-ABL1 and rely on conversion of values to the international reporting scale for appropriate clinical interpretation. However, the technique has a degree of inherent variability despite standardized procedures, which means care should be taken by the clinician when assessing response based on BCR-ABL1 cutoff limits. The last few years have witnessed the emergence of a new molecular response target, which is the achievement and maintenance of a deep molecular response. The ability to achieve treatment-free remission for some patients has shifted the relevant boundary for molecular response. However, the definitive safe BCR-ABL1 transcript level and length of the maintenance phase after which treatment cessation can be attempted has not yet been determined. For patients with TKI resistance, BCR-ABL1 kinase domain mutation analysis remains an essential assessment to guide therapy. Furthermore, low-level mutation detection is clinically relevant for response prediction to subsequent TKI therapy for some patients. Multiple low-level mutations may be a biomarker of a clonally diverse disease with the propensity for resistance evolution. Overall, molecular monitoring, including low-level monitoring is a fundamental component of management for patients with CML.

Concordant optimal molecular and cytogenetic responses at both 3 and 6 months predict a higher probability of MR4.5 achievement in patients with chronic myeloid leukemia treated with imatinib

To investigate the impact of the combination of early molecular and cytogenetic responses on the achievement of MR4.5, 228 newly diagnosed chronic phase chronic myeloid leukemia patients treated with imatinib were categorized into 3-month and 6-month concordant optimal, discordant, concordant warning, and failure groups. Among them, 85.3% at 3 months and 78.1% at 6 months had concordant molecularly and cytogenetically defined responses. At both 3 and 6 months, patients with discordant, concordant warning and failure responses had similar 3-year MR4.5 rates, and all were significantly lower than the rate in patients with concordant optimal responses. Patients with concurrent 3-month and 6-month concordant optimal responses had a significantly higher 3-year MR4.5 rate than those with other responses, and 3-month and 6-month concurrent molecular optimal, but not cytogenetic optimal responses. Therefore, achieving concordant optimal molecular and cytogenetic responses at both 3 and 6 months with imatinib treatment are associated with MR4.5 achievement.

Measurement of BCR-ABL1 transcripts on the International Scale in the United States: current status and best practices

Chronic myeloid leukemia (CML) results from the Philadelphia chromosome (Ph) translocation and expression of its fusion oncoprotein BCR-ABL1. BCR-ABL1 tyrosine kinase inhibitors (TKIs) are the standard therapy for Ph-positive CML. Achievement of deep molecular responses (typically defined as ≥4-log reduction in BCR-ABL1 RNA levels) is an emerging treatment goal becoming attainable for more patients due to the availability of second-generation TKIs. Deep molecular responses are associated with improved long-term outcomes and are required prior to attempting cessation of treatment in treatment-free remission clinical trials. The National Comprehensive Cancer Network and European LeukemiaNet recommend regular monitoring of BCR-ABL1 RNA levels using real-time quantitative polymerase chain reaction (RQ-PCR). However, BCR-ABL1 RQ-PCR is a complex laboratory-developed test; routine quantitative results from clinical diagnostic laboratories may differ from those used to establish the recommendations. Although an International Scale (IS) was developed for standardized reporting of BCR-ABL1 RNA levels, IS adoption has been slow in the United States, but is now used by the vast majority of laboratories. Here, we discuss the importance of molecular monitoring in CML, gaps between current and best molecular monitoring practices in the United States, and challenges and potential solutions for universal IS adoption in the United States.

Discontinuing Tyrosine Kinase Inhibitor Therapy in Chronic Myelogenous Leukemia: Current Understanding and Future Directions

BCR-ABL1 tyrosine kinase inhibitors (TKIs) have dramatically transformed the treatment of patients with chronic myelogenous leukemia (CML). Given the impressive and sustained response to TKI therapy that the majority of treated patients with CML enjoy, recent studies have explored the potential to achieve treatment-free remission in select patients, which may allow these patients to escape the adverse clinical and financial effects associated with life-long TKI therapy. The results of multiple prospective trials have demonstrated that patients who maintain a deep molecular response for at least 2 years with TKI treatment may be eligible for trial of TKI discontinuation. Mounting data indicates that approximately 40% of those who discontinue therapy on trial will remain in remission at least 1 year after TKI discontinuation; the majority of patients with molecular recurrence relapse within the first 6 months after TKI discontinuation, and TKI retreatment is highly effective in restoring response. Sokol score, duration of TKI therapy, depth of molecular response, and the presence of natural killer cells may all be associated with a higher probability of attaining treatment-free remission. Moving forward, emerging data from ongoing TKI discontinuation trials will allow for appropriate selection of patients with CML eligible for this approach, will expand our current understanding of the CML stem cell, and identify therapeutic interventions capable of effectively deleting the malignant hematopoietic stem cell.

Impact of ELN recommendations in the management of first-line treated chronic myeloid leukaemia patients: a French cross-sectional study

The availability of tyrosine kinase inhibitors has extended therapeutic options for chronic myeloid leukaemia (CML) patients. Monitoring recommendations and clinical response goals have recently been updated. The objective of this study was to describe the profile of CML patients in chronic phase currently receiving first-line therapy, including treatment, monitoring and response kinetics. A multicentre, cross-sectional, epidemiological survey in unselected chronic phase CML patients in France attending consultations during a one-month period was performed. 438 of 697 (62·8%) reported patients were currently receiving first-line treatment and were analysed. Imatinib was the most frequently received treatment (72·4% of patients). Retrospective cytogenetic and molecular assessments at 3, 6, 12 or 18 months were available in 88·4% of patients. At the 12-month assessment, 32·2% were not in major molecular response (MMR). At last assessment, among 355 patients with duration of treatment ≥ 12 months, 91·5% had achieved MMR and 66·5% were in deep molecular response. This study, performed in everyday practice population of CML patients, suggests that monitoring of molecular responses in real-life practice is aligned with European LeukaemiaNet recommendations. The majority of patients still receiving first-line treatment are in optimal response, with a few being classified as in the warning area or responding to failure.

Best Practices in Chronic Myeloid Leukemia Monitoring and Management

: Optimal use of current therapeutic opportunities for chronic myeloid leukemia patients requires integration of clinical and laboratory monitoring. Assessment of molecular response (MR) by real-time quantitative polymerase chain reaction is the most sensitive way to monitor tyrosine kinase inhibitor (TKI) treatment efficacy. Besides major molecular response, which has emerged as a safe haven for survival since the initial studies of first-line imatinib treatment, two additional MR milestones have recently been defined: early molecular response and deep molecular response. The achievement of such MR milestones within defined time points during therapy is thought to draw the ideal trajectory toward optimal long-term outcome and, possibly, successful treatment discontinuation. Sensitive and reproducible MR measurement and proper interpretation of MR results are therefore critical to correctly inform therapeutic decisions. In patients who do not achieve an optimal response to TKI therapy, BCR-ABL1 mutation screening should also be performed, because it may deliver useful information for TKI choice. This review aims to help clinicians apply and translate the latest response definitions and clinical recommendations into practice. We provide a critical update on how these recommendations have incorporated MR levels in the clinical decision algorithms and how detection of BCR-ABL1 mutations should be interpreted. We also include a practical guide for pathologists and molecular biologists to best perform molecular testing and for hematologists and oncologists to best integrate it into routine practice.

IMPLICATIONS FOR PRACTICE

Ever-more-potent therapeutic strategies have been developed for chronic myeloid leukemia (CML) in parallel with the evolution of therapeutic goals and the refinement of response definitions and monitoring schemes and procedures. Terminology and methodology continue to evolve rapidly, making it difficult for busy hematology/oncology professionals to keep abreast of the newest developments. Optimal CML patient management results from the timely and rational use of molecular testing, the critical assessment of the power and pitfalls of current technology, and the appropriate interpretation and contextualization of results.

Present and future of molecular monitoring in chronic myeloid leukaemia

Currently, physicians treating chronic myeloid leukaemia (CML) patients can rely on a wide spectrum of therapeutic options: the best use of such options is essential to achieve excellent clinical outcomes and, possibly, treatment-free remission (TFR). To accomplish this, proper integration of expert clinical and laboratory monitoring of CML patients is fundamental. Molecular response (MR) monitoring of patients at defined time points has emerged as an important success factor for optimal disease management and BCR-ABL1 kinase domain mutation screening is useful to guide therapeutic reassessment in patients who do not achieve optimal responses to tyrosine kinase inhibitor therapy. Deeper MRs might be associated with improved long-term survival outcomes. More importantly, they are considered a gateway to TFR. In molecular biology, novel procedures and technologies are continually being developed. More sophisticated molecular tools and automated analytical solutions are emerging as CML treatment endpoints and expectations become more and more ambitious. Here we provide a critical overview of current and novel methodologies, present their strengths and pitfalls and discuss what their present and future role might be.

Cost-effectiveness of Tyrosine Kinase Inhibitor Treatment Strategies for Chronic Myeloid Leukemia in Chronic Phase After Generic Entry of Imatinib in the United States

Background:

We analyzed the cost-effectiveness of treating incident chronic myeloid leukemia in chronic phase (CML-CP) with generic imatinib when it becomes available in United States in 2016. In the year following generic entry, imatinib’s price is expected to drop 70% to 90%. We hypothesized that initiating treatment with generic imatinib in these patients and then switching to the other tyrosine-kinase inhibitors (TKIs), dasatinib or nilotinib, because of intolerance or lack of effectiveness (“imatinib-first”) would be cost-effective compared with the current standard of care: “physicians’ choice” of initiating treatment with any one of the three TKIs.

Methods:

We constructed Markov models to compare the five-year cost-effectiveness of imatinib-first vs physician’s choice from a US commercial payer perspective, assuming 3% annual discounting ($US 2013). The models’ clinical endpoint was five-year overall survival taken from a systematic review of clinical trial results. Per-person spending on incident CML-CP treatment overall care components was estimated using Truven’s MarketScan claims data. The main outcome of the models was cost per quality-adjusted life-year (QALY). We interpreted outcomes based on a willingness-to-pay threshold of $100 000/QALY. A panel of European LeukemiaNet experts oversaw the study’s conduct.

Results:

Both strategies met the threshold. Imatinib-first ($277 401, 3.87 QALYs) offered patients a 0.10 decrement in QALYs at a savings of $88 343 over five years to payers compared with physician’s choice ($365 744, 3.97 QALYs). The imatinib-first incremental cost-effectiveness ratio was approximately $883 730/QALY. The results were robust to multiple sensitivity analyses.

Conclusion:

When imatinib loses patent protection and its price declines, its use will be the cost-effective initial treatment strategy for CML-CP.