European LeukemiaNet criteria for failure or suboptimal response reliably identify patients with CML in early chronic phase treated with imatinib whose eventual outcome is poor

Low-Dose Dasatinib (50 mg Daily) Frontline Therapy in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia: 5-Year Follow-Up Results

BACKGROUND

Dasatinib is a BCR::ABL1 tyrosine kinase inhibitor approved as frontline therapy at a 100 mg daily for chronic myeloid leukemia in chronic phase (CML-CP). The use of a lower dose of dasatinib (50 mg daily) has demonstrated better tolerance and improved outcomes compared with the standard dose. Here, we report the updated results in a large cohort with a 5-year follow-up.

PATIENTS AND METHODS

Patients with newly diagnosed CML-CP were eligible. Entry and response-outcome criteria were standard. Dasatinib was given as 50 mg orally daily.

RESULTS

Eighty-three patients were included. At 3 months, 78 (96%) patients achieved BCR::ABL1 transcripts (IS) ≤10%, and at 12 months, 65 (81%) patients achieved BCR::ABL1 transcript (IS) ≤0.1%. The cumulative incidence of complete cytogenetic, major molecular, and deep molecular responses at 5 years were 98%, 95%, and 82%, respectively. Rates of failures due to resistance (n = 4; 5%) and toxicity (n = 4; 5%) were low. The 5-year overall survival was 96% and event-free survival 90%. No transformations to accelerated or blastic phase were observed. Grade 3 to 4 pleural effusions developed in 2% of patients.

CONCLUSION

Dasatinib 50 mg daily is an effective and safe treatment for newly diagnosed CML-CP.

BCR/ABL1ΔE7-8-9 isoform contributes to tyrosine kinase inhibitor resistance in chronic myeloid leukemia

In chronic myeloid leukemia (CML) patients, the involvement of the BCR/ABL1 isoform in tyrosine kinase inhibitors (TKIs) resistance has attracted lots of attention. In this work, a novel isoform that encoded truncated protein due to the deletion of ABL1 exon7, 8, and 9 was reported and named BCR/ABL1ΔE7-8-9 here. This isoform was detected only in 10.2% of CML patients with inadequate responses to TKIs. BCR/ABL1Δexon7-8-9 isoform promoted S phase cell proliferation and reduced the expression of fusion gene and ABL1 phosphorylation level more slowly than that of control cells after TKIs treatment. The novel isoform has the qualities of a functional tyrosine kinase, localized in the cytoplasm, and could not be imported into the nucleus by TKIs. These results indicated that BCR/ABL1Δexon7-8-9 showed poorer sensitivity to imatinib and nilotinib than wild-type BCR/ABL1. According to molecular docking studies, nilotinib and imatinib present different binding sites and have a lower binding capacity with BCR/ABL1ΔE7-8-9 protein than the wild type. Our findings suggested that the novel isoform BCR/ABL1ΔE7-8-9 may contribute to TKIs resistance in CML due to its weakened TKIs binding ability. It enriched the mechanism of spliceosome involved in TKIs resistance. Monitoring the expression of BCR/ABL1ΔE7-8-9 helps guide the treatment of CML patients in the clinic.

OCT-1 Expression in Patients with Chronic Myeloid Leukemia: A Comparative Analysis with Respect to Response to Imatinib Treatment

The introduction of tyrosine kinase inhibitors (TKI) has resulted in a significant improvement in the treatment of CML patients. However, some CML patients are resistant to imatinib therapy, the initial TKI therapy in the CML. Therefore, it is important to find prognostic markers for resistance. The OCT-1 gene involved in imatinib uptake is also suspected to cause imatinib resistance. The aim of this study was to investigate the role of OCT-1 in imatinib resistance by comparing OCT-1 expression levels in imatinib resistant and imatinib sensitive patients with chronic myeloid leukemia (CML). This study was conducted on 101 patients with CML [imatinib sensitive (n = 51) and imatinib resistant (n = 50)] who were treated with imatinib. Gene expression analysis was done using QRT-PCR. The relative expression levels of OCT-1 were calculated using 2(-ΔΔCT) method. OCT1 mRNA expression levels were 0.149 (0.011-2.532) and 0.119 (0.008-2.868) in imatinib-sensitive group and imatinib-resistant group, respectively. OCT-1 expression levels were not significantly different in the imatinib-sensitive group when compared to imatinib resistant group (p > 0.05). OCT-1 expression was also similar in BCR-ABL1 kinase domain mutation positive and negative cases (p > 0.05). The imatinib-resistant group had a higher rate of hydroxyurea or interferon-alpha treatment prior to imatinib therapy and a lower rate for first-line imatinib as the only treatment than the imatinib-sensitive group (p = 0.002 and p = 0.002, respectively). According to the results of our study, OCT-1 does not have a biomarker feature in the evaluation of imatinib response. In addition, the study should be performed in larger patient groups.

Correlation of the transcription factors IRF4 and BACH2 with the abnormal NFATC1 expression in T cells from chronic myeloid leukemia patients

OBJECTIVE

T cell dysfunction is a common characteristic of patients with myeloid leukemia and is closely related to clinical efficacy and prognosis. In order to clarify the mechanisms leading to the T cell dysfunction, we characterized the gene expression profile of T cells from chronic myelogenous leukemia (CML) patients by microarray analysis and investigated the related regulating pathway.

METHODS

We employed gene expression profiling, bioinformatics and real-time quantitative reverse transcription PCR (RT-qPCR) to detect genes differentially expressed in CML patients versus healthy donors.

RESULTS

There were 1704 genes differentially expressed between CD3⁺ T cells from CML patients and healthy donors, including 868 up-regulated genes and 836 down-regulated genes, which mostly related to T cell functional pathways. In particular, lower expression of NFATC1, a member of the TCR signaling pathway, was detected in CD3⁺ T cells from CML patients. We further found that the expression of IRF4 and BACH2, transcription factors that potentially regulate NFATC1, in CD3⁺ T cells from CML patients was significantly lower than that in healthy donors.

CONCLUSION

We for the first time observed the altered gene expression profiles of CD3⁺ T cells from CML patients, and the results suggested that IRF4, BACH2 and NFATC1 may be involved in regulating T cell dysfunction in CML patients in the form of a transcriptional regulatory network. These findings may provide potential targets for tyrosine kinase inhibitors in combination with other targeted immunotherapies .

Discontinuation of Tyrosine Kinase Inhibitors in Patients with Chronic Myeloid Leukemia: a Review of the Biological Factors Associated with Treatment-Free Remission

Purpose of Review

Clinical factors alone do not enable us to differentiate which patients will maintain treatment-free remission (TFR) from those who are likely to relapse. Thus, patient-specific factors must also play a role. This review will update the reader on the most recent studies presenting biological factors that can help predict tyrosine kinase inhibitor (TKI) discontinuation success.

Recent Findings

Cellular and molecular factors with a suggested role in TFR include immune factors and leukemic stem cell (LSC) persistence; the BCR::ABL1 transcript type, halving time, and BCR::ABL1 DNA and RNA positivity; as well as other molecular factors such as somatic mutations, RNA expression, and telomere length.

Summary

Our review presents several biomarkers with predictive value for TFR but also highlights areas of unmet need. Future discontinuation guidelines will likely include biological factors for the personalization of TFR prediction. However, it will be important that such advances do not prevent more patients from making a TKI discontinuation attempt.

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.

How I Treat Chronic Phase Chronic Myelogenous Leukemia

When imatinib, the first tyrosine kinase inhibitor (TKI) developed for use in chronic myelogenous leukemia (CML) was approved in 2001, the treatment of this disease was forever changed. Significant reductions in the molecular burden of disease were seen with the first generation TKI imatinib and with the addition of dasatinib (2006), nilotinib (2007), bosutinib (2012) and ponatinib (2013), deeper and more rapid reductions were noted. Physicians could begin to tailor TKI therapy to individual patients, and patients who did not respond to or could not tolerate first line therapy now had options. Importantly, the number of patients who developed accelerated or blast phase disease decreased dramatically. Research in CML continues to evolve and by presenting illustrative cases, this article will review some of the newer aspects of clinical care in this disease. Updated information regarding bosutinib and asciminib, the latter currently in clinical trials, will be presented; bosutinib is of particular interest as the drug's transit through the United States Food and Drug Administration (FDA) highlights the question of what is considered optimal response to TKI therapy. The challenge of understanding the cardiac safety data of ponatinib and the unique dosing schedule based on individual response will be discussed. Lastly, two cases will focus on features of TKI treatment that -remarkably- have become part of the treatment algorithm: family planning for women with CML and stopping therapy after meeting a specific treatment milestone.

Influence of genetic polymorphisms in glutathione-S-transferases gene in response to imatinib among Brazilian patients with chronic myeloid leukemia

Polymorphism in metabolizing enzymes can influence drug response as well as the risk for adverse drug reactions. Nevertheless, there are still few studies analyzing the consequence of polymorphisms for the Glutathione-S-transferases (GST) gene to drug response in chronic myeloid leukemia (CML). This study reports, the influence of GSTP1*B and GSTT1/GSTM1null polymorphisms in response to imatinib in CML patients in a Brazilian population. One hundred thirty-nine CML patients from the Clinical Hospital of Goiânia, Goiás, Brazil, treated with imatinib were enrolled in this study. Genotyping of GSTT1 and GSTM1 genes deletions were performed by qPCR and of GSTP1 gene was performed by RFLP-PCR. The frequency of GSTP1*1B, GSTT1 and GSTM1null polymorphisms were determined for all patients. The influence of each patient's genotypes was analyzed with the patient's response to imatinib treatment. Brazilian CML patients revealed GSTT1 and GSTM1 genes deletions. GSTT1 deletion was found in 19.3% of patients and GSTM1 deletion in 48.7% of patients with CML. GSTT1/GSTM1 deletion was found in 11.7% in Brazilian CML patients. The "G allele" of GSTP1*B, is associated with later cytogenetic response in imatinib therapy. While, the gene presence combined with GG genotype (GSTM1 present/GSTPI-GG) conferred a tend to a later cytogenetic response to patients. GSTP1*B and GSTT1/GSTM1null polymorphisms influence treatment response in CML. Brazilian CML patients presenting GSTP1 AA/AG genotypes alone and in combination with GSTT1 null reach the cytogenetic response faster, while patients presenting GSTP1-GG and GSTMI positive genotypes may take longer to achieve cytogenetic response. As a result, it allows a better prognosis, with the use of an alternative therapy, other than reducing treatment cost.

CML Chapter

The discovery of the tyrosine kinase inhibitor (TKI) imatinib in the early 2000's revolutionized the treatment and prognosis of patients with chronic myeloid leukemia (CML) [Hochhaus et al. in N Engl J Med 376:917-927, 2017]. The treatment of patients with CML has changed dramatically since the approval of imatinib and other TKIs. Before the TKI era, newly diagnosed patients would undergo HLA typing to try to identify a well-matched donor, and then proceed quickly to allogeneic hematopoietic cell transplantation (HCT). With the introduction of imatinib followed a few years later by dasatinib, nilotinib, then bosutinib, treatment approaches changed in a dramatic way. Transplantation is no longer an upfront treatment option for newly diagnosed CML patients, and in fact, it is very rarely used in the management of a patient with CML currently. The management of CML patients has been a model of personalized medicine or targeted therapy that is being emulated in the treatment of many other hematologic malignancies and solid tumors such as lung cancer [Soverini et al. in Mol Cancer 17:49, 2018]. The Philadelphia Chromosome (Ph) which leads to the formation of the BCR-ABL fusion gene and its product the BCR-ABL protein is the cause of CML. With effective targeting of this protein with the available TKIs, the disease is completely controllable if not curable for most patients. Life expectancy for patients with CML is essentially normal. Quality of life becomes an important goal including the potential for pregnancy, and ultimately the chance to discontinue all TKI therapy permanently. The three cases outlined below serve to highlight some of the important issues in the management of patients with CML in the post-TKI era.

Standardization of BCR-ABL1 p210 Monitoring: From Nested to Digital PCR

The introduction of tyrosine kinase inhibitors in 2001 as a targeted anticancer therapy has significantly improved the quality of life and survival of patients with chronic myeloid leukemia. At the same time, with the introduction of tyrosine kinase inhibitors, the need for precise monitoring of the molecular response to therapy has emerged. Starting with a qualitative polymerase chain reaction, followed by the introduction of a quantitative polymerase chain reaction to determine the exact quantity of the transcript of interest-p210 BCR-ABL1, molecular monitoring in patients with chronic myeloid leukemia was internationally standardized. This enabled precise monitoring of the therapeutic response, unification of therapeutic protocols, and comparison of results between different laboratories. This review aims to summarize the steps in the diagnosis and molecular monitoring of p210 BCR-ABL1, as well as to consider the possible future application of a more sophisticated method such as digital polymerase chain reaction.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

Organic Cation Transporters in Health and Disease

The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.

[Efficacy of nilotinib in the first-line treatment of chronic myeloid leukemia and the analysis of factors affecting molecular responses]

Objectives: This study aimed to investigate the efficacy and safety of nilotinib as the first-line treatment for patients with chronic myelogenous leukemia (CML) and analyze the factors affecting the realization of the major molecular response. Methods: A retrospective study was conducted on 86 newly diagnosed CML patients from the Affiliated Cancer Hospital of Zhengzhou University from January 2014 to June 2017, who were using nilotinib 300 mg, twice a day, as the first-line treatment. There were 49 males and 37 females. Results: At 12 months, the MMR, MR4, and MR4.5 rates were 59.3%, 22.1%, and 15.1%, respectively. At 24 months, the MMR, MR4, and MR4.5 rates were 76.2%, 44.0%, and 27.4%, respectively.The median follow-up time was 42 months (range, 21-66 months) . The median progression-free survival time (PFS) was 42 months (range, 9-66 months) at a PFS rate of 93%. The time required for BCR-ABL transcript to decrease by half compared with the diagnosis was defined as the halving time (HT) . HT was the influencing factor of the 12-month MMR (OR=0.896, P<0.001) and MR4.5 (OR=0.377, P=0.003) . The most common non-hematologic adverse reactions were rash (37.2%) and headache (32.6%) , and most were grade 1/2. The most common hematologic adverse reactions were mainly neutropenia (27.9%) and thrombocytopenia (32.4%) . Conclusion: Nilotinib was an effective and safe first-line treatment for CML patients. HT ≤ 13.68 days is protective factor for long-term progression-free survival.

Dasatinib vs. imatinib in patients with chronic myeloid leukemia in chronic phase (CML-CP) who have not achieved an optimal response to 3 months of imatinib therapy: the DASCERN randomized study

Early molecular response is associated with improved probability of deep molecular response and superior survival in patients with CML-CP. However, ~1 in 3 patients on first-line imatinib do not achieve this threshold. The phase 2b DASCERN trial (NCT01593254) assessed the outcome of early switch to dasatinib in patients with suboptimal response to first-line imatinib. Adult patients with CML-CP were randomized (2:1) to receive 100 mg dasatinib (n = 174) or continue imatinib at ≥400 mg (n = 86). The primary endpoint was the rate of major molecular response (MMR) at 12 months, which was 29% (dasatinib) and 13% (imatinib; P = 0.005). After ≥2 years of follow-up, 45 patients (52%) randomized to continue imatinib had crossed over to dasatinib. Considering treatment crossover, the 2-year cumulative MMR rate was 64% with dasatinib and 41% with imatinib (66% and 67%, respectively by intent-to-treat). Adverse events were consistent with the established safety profiles of both drugs. The results of this first prospective study support early monitoring of patients treated with first-line imatinib, and suggest that switching to dasatinib in cases of suboptimal response may offer clinical benefit. Further follow-up is needed to assess the long-term clinical benefit of early switching.

Early Prediction of Subsequent Molecular Response to Nilotinib in Patients with Chronic Myeloid Leukemia: Comparison of the Quantification of BCR-ABL1 Ratios Using ABL1 or GUSB Control Genes

Molecular monitoring of BCR-ABL1 transcripts is a critical prognostic indicator of treatment response in chronic myeloid leukemia (CML). Quantification of BCR-ABL1 transcripts using ABL1 or GUSB as control genes on the early molecular response (MR) to frontline nilotinib was studied using data from 60 patients with chronic-phase CML from the Evaluating Nilotinib Efficacy and Safety in Clinical Trials as First-Line Treatment (ENEST1st) substudy. Effects of BCR-ABL1/ABL1 and BCR-ABL1/GUSB ratios at early time points as independent variables on subsequent MR were determined by logistic regression analyses and predictive cut-off values determined by receiver operating curve analyses. From day 45, concordance was found for both control genes' early transcript kinetics and ability to predict subsequent deep MR at 18 months. From baseline to 3 months, transcripts descended linearly with both control genes. Use of ABL1 allowed for an earlier prediction (2 months) of subsequent MR than with GUSB (3 months), with cut-off values of 1.5% and 0.19%, respectively. The dynamic determination of BCR-ABL1 transcripts using either internal control gene is valid and predictive of subsequent MR. The use of GUSB to predict an earlier and more accurate response than ABL1 is not supported in the results. Accurate early indicators of MR are essential to identify patients likely to have inferior outcomes who may benefit from treatment with an alternative tyrosine kinase inhibitor.

A randomised phase II trial of hydroxychloroquine and imatinib versus imatinib alone for patients with chronic myeloid leukaemia in major cytogenetic response with residual disease

In chronic-phase chronic myeloid leukaemia (CP-CML), residual BCR-ABL1+ leukaemia stem cells are responsible for disease persistence despite TKI. Based on in vitro data, CHOICES (CHlorOquine and Imatinib Combination to Eliminate Stem cells) was an international, randomised phase II trial designed to study the safety and efficacy of imatinib (IM) and hydroxychloroquine (HCQ) compared with IM alone in CP-CML patients in major cytogenetic remission with residual disease detectable by qPCR. Sixty-two patients were randomly assigned to either arm. Treatment 'successes' was the primary end point, defined as ≥0.5 log reduction in 12-month qPCR level from trial entry. Selected secondary study end points were 24-month treatment 'successes', molecular response and progression at 12 and 24 months, comparison of IM levels, and achievement of blood HCQ levels >2000 ng/ml. At 12 months, there was no difference in 'success' rate (p = 0.58); MMR was achieved in 80% (IM) vs 92% (IM/HCQ) (p = 0.21). At 24 months, the 'success' rate was 20.8% higher with IM/HCQ (p = 0.059). No patients progressed. Seventeen serious adverse events, including four serious adverse reactions, were reported; diarrhoea occurred more frequently with combination. IM/HCQ is tolerable in CP-CML, with modest improvement in qPCR levels at 12 and 24 months, suggesting autophagy inhibition maybe of clinical value in CP-CML.

Tyrosine kinase inhibitors induce alternative spliced BCR-ABLIns35bp variant via inhibition of RNA polymerase II on genomic BCR-ABL

To elucidate dynamic changes in native BCR-ABL and alternatively spliced tyrosine kinase inhibitor (TKI)-resistant but function-dead BCR-ABL^Ins35bp variant, following commencement or discontinuation of TKI therapy, each transcript was serially quantified in patients with chronic myeloid leukemia (CML) by deep sequencing. Because both transcripts were amplified together using conventional PCR system for measuring International Scale (IS), deep sequencing method was used for quantifying such BCR-ABL variants. At the initial diagnosis, 7 of 9 patients presented a small fraction of cells possessing BCR-ABL^Ins35bp , accounting for 0.8% of the total IS BCR-ABL, corresponding to actual BCR-ABL^Ins35bp value of 1.1539% IS. TKI rapidly decreased native BCR-ABL but not BCR-ABL^Ins35bp , leading to the initial increase in the proportion of BCR-ABL^Ins35bp . Thereafter, both native BCR-ABL and BCR-ABL^Ins35bp gradually decreased in the course of TKI treatment, whereas small populations positive for TKI-resistant BCR-ABL^Ins35bp continued fluctuating at low levels, possibly underestimating the molecular response (MR). Following TKI discontinuation, sequencing analysis of 54 patients revealed a rapid relapse, apparently derived from native BCR-ABL⁺ clones. However, IS fluctuating at low levels around MR4.0 marked a predominant persistence of cells expressing function-dead BCR-ABL^Ins35bp , suggesting that TKI resumption was unnecessary. We clarified the possible mechanism underlying mis-splicing BCR-ABL^Ins35bp , occurring at the particular pseudo-splice site within intron8, which can be augmented by TKI treatment through inhibition of RNA polymerase II phosphorylation. No mutations were found in spliceosomal genes. Therefore, monitoring IS functional BCR-ABL extracting BCR-ABL^Ins35bp would lead us to a correct evaluation of MR status, thus determining the adequate therapeutic intervention.

Response and Resistance to BCR-ABL1-Targeted Therapies

Chronic myeloid leukemia (CML), caused by constitutively active BCR-ABL1 fusion tyrosine kinase, has served as a paradigm for successful application of molecularly targeted cancer therapy. The development of the tyrosine kinase inhibitor (TKI) imatinib allows patients with CML to experience near-normal life expectancy. Specific point mutations that decrease drug binding affinity can produce TKI resistance, and second- and third-generation TKIs largely mitigate this problem. Some patients develop TKI resistance without known resistance mutations, with significant heterogeneity in the underlying mechanism, but this is relatively uncommon, with the majority of patients with chronic phase CML achieving long-term disease control. In contrast, responses to TKI treatment are short lived in advanced phases of the disease or in BCR-ABL1-positive acute lymphoblastic leukemia, with relapse driven by both BCR-ABL1 kinase-dependent and -independent mechanisms. Additionally, the frontline CML treatment with second-generation TKIs produces deeper molecular responses, driving disease burden below the detection limit for a greater number of patients. For patients with deep molecular responses, up to half have been able to discontinue therapy. Current efforts are focused on identifying therapeutic strategies to drive deeper molecular responses, enabling more patients to attempt TKI discontinuation.

Optimal treatment strategy with nilotinib for patients with newly diagnosed chronic-phase chronic myeloid leukemia based on early achievement of deep molecular response (MR4.5 ): The phase 2, multicenter N-Road study

For patients who have chronic myeloid leukemia (CML), one of the primary treatment options is administration of nilotinib 300 mg twice daily (BID). In previous studies which compared outcomes associated with nilotinib or imatinib treatment, nilotinib achieved a higher rate of deep molecular response (MR). We conducted a phase II, open‐label, multicenter study to investigate an intrapatient nilotinib dose‐escalation strategy for patients with newly diagnosed chronic‐phase (CP) CML based on early MR^4.5 achievement. The primary study endpoint was achievement of MR^4.5 by 24 months following the initiation of nilotinib 300 mg BID. Fifty‐three patients were enrolled, 51 received nilotinib, and 37 completed the treatment. An increase in the nilotinib dose (to 400 mg BID) was allowed when patients satisfied our criteria for no optimal response at any time point. The median (range) dose intensity was 600 (207‐736) mg/day. Of 46 evaluable patients, 18 achieved an optimal response and 28 did not. Of the latter, nine patients underwent dose escalation to 400 mg BID, and none achieved MR^4.5. The remaining 19 patients could not undergo dose escalation, 12 (63%) because of adverse events (AEs), and 7 (37%) for non‐AE related reasons. Four of these patients achieved MR^4.5. The MR^4.5 rate by 24 months was 45.7%. The progression‐free, overall and event‐free survival were each 97.6%. No new safety concerns were observed. Our findings support the use of continuous nilotinib at a dose of 300 mg BID for newly diagnosed patients with CML‐CP.

Feasibility Study of Switching to Nilotinib After First-line Imatinib in the Chronic Phase of Chronic Myeloid Leukemia

BACKGROUND

We investigated the real-life choice of first-line treatment in the chronic phase of chronic myeloid leukemia (CML-CP) and the feasibility of switching to nilotinib after first-line imatinib.

PATIENTS AND METHODS

We performed a retrospective analysis of the efficacy and safety of imatinib versus nilotinib as first-line therapy for patients with CML-CP. We also performed a comparative analysis of the efficacy of sustained imatinib versus a switch to nilotinib for patients with CML-CP with a warning or failure response or intolerance to imatinib. We also comparatively analyzed the efficacy between first-line nilotinib and first-line imatinib after standardized management in accordance with the European Leukemia Network (ELN) recommendations. A total of 344 patients were included in the present study.

RESULTS

The proportion of patients achieving a complete cytogenetic response (CCyR), major molecular response (MMR), and molecular response 4.0 (MR4.0) was greater with first-line nilotinib than with first-line imatinib at 0 to 24 and 0 to 36 months (P < .05). Of the 344 patients, 174 did not achieve an optimal response to first-line imatinib. A greater proportion of those patients who had switch to nilotinib had achieved a CCyR, MMR, and MR4.0 compared with those continuing imatinib for 12 months of subsequent treatment (P < .005). No difference was found in the proportion of patients with a CCyR, MMR, and MR4.0 between first-line nilotinib and first-line imatinib after standardized management in accordance with the ELN recommendations at 0 to 24 and 0 to 36 months (P > .05).

CONCLUSION

First-line imatinib can result in efficacy similar to that with first-line nilotinib after standardized management in accordance with the ELN recommendations. Treatment with imatinib as first-line treatment, with a switch to nilotinib after standardized management is feasible and effective.

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Monitoring Chronic Myeloid Leukemia: How Molecular Tools May Drive Therapeutic Approaches

More than 15 years ago, imatinib entered into the clinical practice as a "magic bullet"; from that point on, the prognosis of patients affected by chronic myeloid leukemia (CML) became comparable to that of aged-matched healthy subjects. The aims of treatment with tyrosine kinase inhibitors (TKIs) are for complete hematological response after 3 months of treatment, complete cytogenetic response after 6 months, and a reduction of the molecular disease of at least 3 logs after 12 months. Patients who do not reach their goal can switch to another TKI. Thus, the molecular monitoring of response is the main consideration of management of CML patients. Moreover, cases in deep and persistent molecular response can tempt the physician to interrupt treatment, and this "dream" is possible due to the quantitative PCR. After great international effort, today the BCR-ABL1 expression obtained in each laboratory is standardized and expressed as "international scale." This aim has been reached after the establishment of the EUTOS program (in Europe) and the LabNet network (in Italy), the platforms where biologists meet clinicians. In the field of quantitative PCR, the digital PCR is now a new and promising, sensitive and accurate tool. Some authors reported that digital PCR is able to better classify patients in precise "molecular classes," which could lead to a better identification of those cases that will benefit from the interruption of therapy. In addition, digital PCR can be used to identify a point mutation in the ABL1 domain, mutations that are often responsible for the TKI resistance. In the field of resistance, a prominent role is played by the NGS that enables identification of any mutation in ABL1 domain, even at sub-clonal levels. This manuscript reviews how the molecular tools can lead the management of CML patients, focusing on the more recent technical advances.

Comparative efficacy and tolerability of front-line treatments for newly diagnosed chronic-phase chronic myeloid leukemia: an update network meta-analysis

Background

Recent years have witnessed the rapid evolution of therapies in chronic-phase chronic myeloid leukemia (CP-CML). To assess the efficacy and tolerability of all reported front-line treatments for patients with newly diagnosed CML, a multiple-treatments meta-analysis was performed, which accounted for both direct and indirect comparisons among those treatments.

Methods

Primary outcomes were the percentage of patients achieving major molecular response (MMR) and complete cytogenetic response (CCyR) within 12 months. Secondary outcomes included the percentage of progression to accelerated phase (AP), serious adverse effects (AEs), overall discontinuation and discontinuation for drug-related AEs. Direct pairwise meta-analysis and indirect multi-comparison meta-analysis among those treatments in each outcome were both conducted. The surface under the cumulative ranking curve (SUCRA) was calculated for all treatments in each outcome. Cluster analysis demonstrated the division of treatments into distinct groupings according to efficacy and tolerability profiles.

Results

A total of 21 randomized controlled trials (RCTs, including 10,187 patients) comparing 15 different interventions for CP-CML patients were included in this study. SUCRA analysis suggested that all tyrosine kinase inhibitors (TKIs) are highly effective in newly diagnosed CP-CML when compared to traditional drugs. Newer TKIs and higher-dose imatinib generally resulted in faster cytogenetic and molecular responses when compared with standard-dose imatinib and traditional drugs. Furthermore, traditional drugs, higher-dose imatinib and newer TKIs demonstrated lower acceptability than standard-dose imatinib. One cluster of interventions, which included nilotinib (300/400 mg BID), dasatinib (100 mg QD) and radotinib (300 mg BID), demonstrated higher efficacy and tolerability than other treatments.

Conclusions

Nilotinib (300/400 mg BID), dasatinib (100 mg QD) and radotinib (300 mg BID) prove to be the most recommended front-line treatments of the greatest efficacy and tolerability for CP-CML patients. High-dose therapies are recommended only for patients in accelerated phase/blast phase or with suboptimal CML-CP response, and management of adverse events should be carried out to avoid compromising the clinical efficacy.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6039-9) contains supplementary material, which is available to authorized users.

Fusion transcripts: Unexploited vulnerabilities in cancer?

Gene fusions are an important class of mutations in several cancer types and include genomic rearrangements that fuse regulatory or coding elements from two different genes. Analysis of the genetics of cancers harboring fusion oncogenes and the proteins they encode have enhanced cancer diagnosis and in some cases patient treatment. However, the effect of the complex structure of fusion genes on the biogenesis of the resulting chimeric transcripts they express is not well studied. There are two potential RNA‐related vulnerabilities inherent to fusion‐driven cancers: (a) the processing of the fusion precursor messenger RNA (pre‐mRNA) to the mature mRNA and (b) the mature mRNA. In this study, we discuss the effects that the genetic organization of fusion oncogenes has on the generation of translatable mature RNAs and the diversity of fusion transcripts expressed in different cancer subtypes, which can fundamentally influence both tumorigenesis and treatment. We also discuss functional genomic approaches that can be utilized to identify proteins that mediate the processing of fusion pre‐mRNAs. Furthermore, we assert that an enhanced understanding of fusion transcript biogenesis and the diversity of the chimeric RNAs present in fusion‐driven cancers will increase the likelihood of successful application of RNA‐based therapies in this class of tumors.

This article is categorized under:

RNA Processing > RNA Editing and Modification

RNA Processing > Splicing Regulation/Alternative Splicing

RNA in Disease and Development > RNA in Disease

European recommendations and quality assurance for cytogenomic analysis of haematological neoplasms

Cytogenomic investigations of haematological neoplasms, including chromosome banding analysis, fluorescence in situ hybridisation (FISH) and microarray analyses have become increasingly important in the clinical management of patients with haematological neoplasms. The widespread implementation of these techniques in genetic diagnostics has highlighted the need for guidance on the essential criteria to follow when providing cytogenomic testing, regardless of choice of methodology. These recommendations provide an updated, practical and easily available document that will assist laboratories in the choice of testing and methodology enabling them to operate within acceptable standards and maintain a quality service.

Identification of TCR Vβ11-2-Dβ1-Jβ1-1 T cell clone specific for WT1 peptides using high-throughput TCRβ gene sequencing

We previously identified a TCR Vβ21 T cell clone which was specific to CML patients, and demonstrated that TCR Vα13/β21 gene-modified CD3+ T cells had specific cytotoxicity for HLA-A11+ K562 cells. However, it remains unclear which antigen is specifically recognized by the TCR Vβ21 T cell clone. In this study, CD3+ T cells from healthy donor peripheral blood were stimulated with the WT1 peptide or mixed BCR-ABL peptides in the presence or absence of IL-2 and IL-7. The distribution of the TCR Vβ repertoire was analyzed after different stimulations. We found that the mixed BCR-ABL peptides induced clonally expanded Vβ7-9-Dβ2-Jβ2-7 T cells while the Wilms Tumor 1 peptide induced clonally expanded Vβ11-2-Dβ1-Jβ1-1 T cells by high-throughput TCRβ sequencing and GeneScan. Interestingly, the sequence and CDR3 motif of Vβ11-2 T cell clone are similar to the TCR Vβ21 (a different TCR V region naming system) T cell clone that we previously found in CML patients. Thus, our findings suggest that the TCR Vβ21 T cell clone found in CML patients might be a T cell clone that specifically recognizes WT1.

[Pre-therapeutic and evolutive characteristics of patients suffering from chronic myeloid leukemia, in Abidjan, Ivory Coast]

INTRODUCTION

The diagnosis of chronic myeloid leukemia is based on the presence of translocation t(9,22). Additional cytogenetic abnormalities may exist at diagnosis and have prognostic value. The authors evaluated the relationship between these additional chromosomal abnormalities, clinical presentation, and therapeutic response.

METHOD

In a retrospective and comparative study from 2005 to 2015, at Yopougon university hospital, 51 cases of myeloid leukemia were selected, including 22 cases with additional chromosomal abnormalities.

RESULTS

Thirteen types of additional Ph1 abnormalities were detected in one group, with a median age of 39years (13-73); a sex ratio of 1.4 and a low social class (49%). The median consultation time is 13months (2-29). Hepatomegaly (54%, P=0.05); fever (81.8%, P=0.0017); bone pain (63.6%, P=0.0001); lymphadenopathies (27.3% P=0.014); poor general condition [WHO>1 (77.3%, P=0.001)], high Sokal index (63.6%, P=0.0019), eosinophilia>5% (72.7, P=0.02) and circulating blastosis were found more frequent in the group with additional abnormalities treated with imatinib mesylate. We obtained 13.6% hematologic remission and 22.7% cytogenetic remission (P=0.02). The average survival was relatively short (20months vs. 76.4months, Log-rank<0.0001). We deplored a high death rate (59.1%).

CONCLUSION

The presence of an additional anomaly constitutes a pejorative element refractory to imatinib.

Digital PCR in Myeloid Malignancies: Ready to Replace Quantitative PCR?

New techniques are on the horizon for the detection of small leukemic clones in both, acute leukemias and myeloproliferative disorders. A promising approach is based on digital polymerase chain reaction (PCR). Digital PCR (dPCR) is a breakthrough technology designed to provide absolute nucleic acid quantification. It is particularly useful to detect a low amount of target and therefore it represents an alternative method for detecting measurable residual disease (MRD). The main advantages are the high precision, the very reliable quantification, the absolute quantification without the need for a standard curve, and the excellent reproducibility. Nowadays the main disadvantages of this strategy are the costs that are still higher than standard qPCR, the lack of standardized methods, and the limited number of laboratories that are equipped with instruments for dPCR. Several studies describing the possibility and advantages of using digital PCR for the detection of specific leukemic transcripts or mutations have already been published. In this review we summarize the available data on the use of dPCR in acute myeloid leukemia and myeloproliferative disorders.

Optimal Time Points for BCR-ABL1 Tyrosine Kinase Domain Mutation Analysis on the Basis of European LeukemiaNet Recommendations in Chronic Myeloid Leukemia

BACKGROUND

In this study we aimed to evaluate appropriate time points for mutation analysis of chronic myeloid leukemia.

PATIENTS AND METHODS

In total, 961 blood samples obtained from 605 chronic-phase chronic myeloid leukemia patients treated with imatinib were subjected to Sanger sequencing to detect BCR-ABL1 mutations. Mutation frequencies at landmark time points (3, 6, and 12 months) were assessed with 16 landmark responses defined by European LeukemiaNet and 2 additional responses, including a complete hematologic response (CHR) at 3 months and a complete cytogenetic response (CCyR) at 12 months.

RESULTS

After 12 months of imatinib treatment of 605 patients, 28 (4.6%) patients harbored 33 mutations, including 23 (69.7%) highly resistant T315I and P-loop mutations. Sequencing data from 650 samples were compared with cytogenetic responses. The mutation frequencies in optimal, warning, and failure groups were 0.5% (2/430), 1.8% (2/110), and 19.1% (21/110), respectively. The molecular response was assessed using 956 samples, and the mutation frequencies were 0.7% (3/425), 3.4% (12/358), and 7.6% (14/173) for the optimal, warning, and failure groups, respectively. For the 2 additional responses, the mutation frequencies in patients with CHR at 3 months and with CCyR at 12 months were 0% (0/160) and 1.7% (4/242), respectively. Overall, mutations were frequently detected at 3-month cytogenetic failure (25.0%), 12-month cytogenetic failure (23.2%), and 6-month cytogenetic failure (10.5%) using response-mutation association analysis.

CONCLUSION

Irrespective of mutation frequency, failure of achievement of a cytogenetic response should be conducted with appropriate mutation analysis.

MR4 sustained for 12 months is associated with stable deep molecular responses in chronic myeloid leukemia

The majority of patients with newly diagnosed chronic myeloid leukemia (CML) will enjoy a life expectancy equivalent to that of unaffected individuals, but will remain on life-long treatment with a concomitant requirement for on-going hospital interactions for molecular monitoring and drug dispensing. In order to determine more accurately the frequency of monitoring required, we performed a 'real-life' retrospective single-center cohort study of 450 patients with CML in at least major molecular remission (MR3) to analyze the risk of loss of MR3 [defined as at least 2 consecutive real-time quantitative polymerase chain reaction (RT-qPCR) results >0.1% International Scale (IS)]. Patients who achieved sustained MR4 (sMR4, BCR-ABL1 RT-qPCR <0.01% IS for 12 months) had a probability of loss of MR3 at 1 and 5 years of 0 and 2.6% (95%CI: 1.2-5.4) respectively, compared to 4.4% (95%CI: 1.9-9.8) and 25.4% (95%CI: 16.7-36.7) respectively, in those who achieved sustained MR3 (sMR3) but not sMR4 (P<0.001). No patient who improved their response to a deep molecular level (at least MR4) lost MR3 if they were considered compliant, had no history of resistance and remained on standard dose tyrosine kinase inhibitor (TKI). MR4 maintained for at least one year represents a secure response threshold for patients with CML, after which no MR3 loss occurs if certain conditions are satisfied (standard TKI dose, full compliance, and lack of previous TKI resistance). This finding may justify reduction of the frequency of hospital interaction, with an associated positive impact on quality of life, survivorship, and economic burden to both patients and healthcare providers.

Nilotinib in the treatment of chronic myeloid leukemia

Nilotinib, a second-generation tyrosine kinase inhibitor, was designed to overcome resistance of a wide range of BCR-ABL mutants to imatinib. When used in the first-line treatment in newly diagnosed  chronic myeloid leukemia (CML), it induces faster and deeper molecular responses in higher than imatinib percentage of patients. Treatment-free remission after achievement of sustained deep molecular response represents an emerging treatment goal for a proportion of patients with CML in chronic phase. The pharmacologic properties, and the role of nilotinib in the current treatment of CML in the context of considered optimal end point of therapy including the discontinuation trial and durable treatment-free remission achievement is discussed in the article.

Molecular monitoring in CML: how deep? How often? How should it influence therapy?

With the advent of tyrosine kinase inhibitors (TKIs), the goals of therapy in chronic myeloid leukemia (CML) are steadily shifting. Long-term disease control on TKI therapy has been the goal and expectation for most patients. More recently, treatment-free remission (TFR) has entered mainstream practice and is increasingly being adopted as the main goal of therapy. This therapeutic shift not only influences TKI selection but also, has necessitated the refinement and dissemination of highly sensitive and accurate molecular monitoring techniques. Measurement of BCR-ABL1 messenger RNA expression through reverse transcription quantitative polymerase chain reaction, reported according to the International Scale, has become the primary tool for response assessment in CML. Achieving specific time-dependent molecular milestones, as defined by global therapeutic guidelines, has been established as critical in maximizing optimal outcomes while identifying patients at risk of therapy failure. Depth and duration of a deep molecular response have become the new therapeutic targets in patients considered for TFR. Consequently, molecular monitoring in CML has become even more critical to ongoing response assessment, identifying patients with TKI resistance and poor drug adherence, and enabling TFR to be attempted safely and effectively.

Molecular monitoring in CML: how deep? How often? How should it influence therapy?

With the advent of tyrosine kinase inhibitors (TKIs), the goals of therapy in chronic myeloid leukemia (CML) are steadily shifting. Long-term disease control on TKI therapy has been the goal and expectation for most patients. More recently, treatment-free remission (TFR) has entered mainstream practice and is increasingly being adopted as the main goal of therapy. This therapeutic shift not only influences TKI selection but also, has necessitated the refinement and dissemination of highly sensitive and accurate molecular monitoring techniques. Measurement of BCR-ABL1 messenger RNA expression through reverse transcription quantitative polymerase chain reaction, reported according to the International Scale, has become the primary tool for response assessment in CML. Achieving specific time-dependent molecular milestones, as defined by global therapeutic guidelines, has been established as critical in maximizing optimal outcomes while identifying patients at risk of therapy failure. Depth and duration of a deep molecular response have become the new therapeutic targets in patients considered for TFR. Consequently, molecular monitoring in CML has become even more critical to ongoing response assessment, identifying patients with TKI resistance and poor drug adherence, and enabling TFR to be attempted safely and effectively.

Successful pregnancies in patients with BCR-ABL-positive leukemias treated with interferon-alpha therapy during the tyrosine kinase inhibitors era

BACKGROUND

Management of pregnant patients with BCR-ABL-positive leukemia is challenging. Managing a patient who has been diagnosed while pregnant requires a different approach as compared to a patient who plans to become pregnant while on the treatment with tyrosine kinase inhibitor (TKI). Interferon (IFN)-alpha is a useful option in both situations due to teratogenic potential of TKIs.

METHODS

We presented a series of 12 successful pregnancies in 11 women with BCR-ABL-positive leukemia, whose leukemia was managed with IFN-alpha throughout their pregnancy.

RESULTS

All children have normal growth and development. All patients remained at least in hematological response and could start or resume TKI after delivery or breastfeeding.

CONCLUSION

Because of the increased risk of teratogenicity and spontaneous abortion in female patient with pregnancy, when receiving TKI, IFN-alpha can be considered a safe drug to be administered throughout pregnancy and could represent the drug of choice in this situation during the era of TKI therapy.

Donor lymphocyte infusion leads to diversity of specific T cell responses and reduces regulatory T cell frequency in clinical responders

T cell responses against malignant cells play a major role in maintaining remission and prolonging overall survival in patients after allogeneic stem cell transplantation and donor lymphocyte infusion (DLI) due to graft-versus-leukemia effect. For better characterization of the T cell responses, we assessed frequency and diversity of leukemia-associated antigen (LAA)-specific cytotoxic T cells using ELISpot and pMHC multimer assays and analyzed the frequency of regulatory T cells (Treg) as well as cytokine profiles before/after DLI. The data were correlated to the clinical course of patients. Significantly more LAA-derived T cell epitopes (p = 0.02) were recognized in clinical responders (R) when compared to nonresponders (NR). In addition, pMHC multimer-based flow cytometry showed a significantly higher frequency of LAA-specific T cells in R versus NR. The frequency of Treg in R decreased significantly (p = 0.008) while keeping stable in NR. No differences in T cell subset analysis before/after DLI were revealed. Clinical responders were correlated to specific immune responses and all clinical responders showed an increase of specific immune responses after DLI. Cytokine assays using enzyme-linked immunosorbent assay showed a significant increase of IL-4 after DLI. Taken together, an increase of specific CTL responses against several LAA after DLI was detected. Moreover, this study suggests that enhanced LAA diversity in T cell responses as well as decreasing numbers of Treg contribute to clinical outcome of patients treated with DLI.

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

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

Clinical results according to age in patients with chronic myeloid leukemia receiving imatinib frontline: The younger, the later, the worse?

OBJECTIVES

To evaluate differences in clinical results according to age among patients with chronic myeloid leukemia (CML).

METHODS

207 consecutive CML patients treated with imatinib frontline were revised, dividing them in young adults (>20 < 45 years) (YA), middle-aged adults (≥45 < 65 years) (MA) and elderly (≥65 years) (EL).

RESULTS

Cumulative incidence of complete cytogenetic response (CCyR) and major molecular response (MMolR) were significantly higher in MA compared with YA and EL (P < .001 for CCyR and P = .001 for MMolR). Number of total events was lower in MA (8 [11.1%] vs 21 [34.4%] in YA and 28 [37.8%] in EL, P = .001): no difference was observed for blastic evolution (P = .478). Number of deaths was higher in the EL (12 [16.2%] vs 2 [3.2%] in YA and 0 in MA, P < .001): however, 11/12 deaths in EL were not related to CML. The PFS curve in MA was significantly longer than in YA and in EL (P = .02). The OS curve in EL was significantly shorter than in YA and in MA (P < .001).

CONCLUSIONS

Age at diagnosis influences significantly the course of CML patients treated with imatinib: a possible explanation of the counterintuitive worse course in YA is the delayed diagnosis compared to elderly.

Generation of V α13/β21+T cell specific target CML cells by TCR gene transfer

Adoptive immunotherapy with antigen-specific T cells can be effective for treating melanoma and chronic myeloid leukemia (CML). However, to obtain sufficient antigen-specific T cells for treatment, the T cells have to be cultured for several weeks in vitro, but in vitro T cell expansion is difficult to control. Alternatively, the transfer of T cell receptors (TCRs) with defined antigen specificity into recipient T cells may be a simple solution for generating antigen-specific T cells. The objective of this study was to identify CML-associated, antigen-specific TCR genes and generate CML-associated, antigen-specific T cells with T cell receptor (TCR) gene transfer. Our previous study has screened an oligoclonal Vβ21 with a different oligoclonal Vα partner in peripheral blood mononuclear cells (PBMCs) derived from patients with CML. In this study, oligoclonally expanded TCR α genes, which pair with TCR Vβ21, were cloned into the pIRES eukaryotic expression vector (TCR Vα-IRES-Vβ21). Next, two recombinant plasmids, TCR Vα13-IRES-Vβ21 and TCR Vα18-IRES-Vβ21, were successfully transferred into T cells, and the TCR gene-modified T cells acquired CML-specific cytotoxicity with the best cytotoxic effects for HLA-A11⁺ K562 cells observed for the TCR Vα13/Vβ21 gene redirected T cells. In summary, our data confirmed TCRVα13/Vβ21 as a CML-associated, antigen-specific TCR. This study provided new evidence that genetically engineered antigen-specific TCR may become a druggable approach for gene therapy of CML.

Persistent detection of alternatively spliced BCR-ABL variant results in a failure to achieve deep molecular response

Treatment with tyrosine kinase inhibitors (TKI) may sequentially induce TKI‐resistant BCR‐ABL mutants in chronic myeloid leukemia (CML). Conventional PCR monitoring of BCR‐ABL is an important indicator to determine therapeutic intervention for preventing disease progression. However, PCR cannot separately quantify amounts of BCR‐ABL and its mutants, including alternatively spliced BCR‐ABL with an insertion of 35 intronic nucleotides (BCR‐ABL^Ins35bp) between ABL exons 8 and 9, which introduces the premature termination and loss of kinase activity. To assess the clinical impact of BCR‐ABL mutants, we performed deep sequencing analysis of BCR‐ABL transcripts of 409 samples from 37 patients with suboptimal response to frontline imatinib who were switched to nilotinib. At baseline, TKI‐resistant mutations were documented in 3 patients, whereas BCR‐ABL^Ins35bp was detected in all patients. After switching to nilotinib, both BCR‐ABL and BCR‐ABL^Ins35bp became undetectable in 3 patients who attained complete molecular response (CMR), whereas in the remaining all 34 patients, BCR‐ABL^Ins35bp was persistently detected, and minimal residual disease (MRD) fluctuated at low but detectable levels. PCR monitoring underestimated molecular response in 5 patients whose BCR‐ABL^Ins35bp was persisted, although BCR‐ABL^Ins35bp does not definitively mark TKI resistance. Therefore, quantification of BCR‐ABL^Ins35bp is useful for evaluating “functional” MRD and determining the effectiveness of TKI with accuracy.

Frontline Dasatinib Treatment in a "Real-Life" Cohort of Patients Older than 65 Years with Chronic Myeloid Leukemia

Dasatinib (DAS) has been licensed for the frontline treatment in chronic myeloid leukemia (CML). However, very few data are available regarding its efficacy and toxicity in elderly patients with CML outside clinical trials. To address this issue, we set out a “real-life” cohort of 65 chronic phase CML patients older than 65 years (median age 75.1 years) treated frontline with DAS in 26 Italian centers from June 2012 to June 2015, focusing our attention on toxicity and efficacy data. One third of patients (20/65: 30.7%) had 3 or more comorbidities and required concomitant therapies; according to Sokal classification, 3 patients (4.6%) were low risk, 39 (60.0%) intermediate risk, and 20 (30.8%) high risk, whereas 3 (4.6%) were not classifiable. DAS starting dose was 100 mg once a day in 54 patients (83.0%), whereas 11 patients (17.0%) received less than 100 mg/day. Grade 3/4 hematologic and extrahematologic toxicities were reported in 8 (12.3%) and 12 (18.5%) patients, respectively. Overall, 10 patients (15.4%) permanently discontinued DAS because of toxicities. Pleural effusions (all WHO grades) occurred in 12 patients (18.5%) and in 5 of them occurred during the first 3 months. DAS treatment induced in 60/65 patients (92.3%) a complete cytogenetic response and in 50/65 (76.9%) also a major molecular response. These findings show that DAS might play an important role in the frontline treatment of CML patients >65 years old, proving efficacy and having a favorable safety profile also in elderly subjects with comorbidities.

An unusual translocation, t(1;11)(q21;q23), in a case of chronic myeloid leukemia with a cryptic Philadelphia chromosome

Chronic myeloid leukemia (CML) is characterized by the translocation t(9;22)(q34;q11) [Philadelphia (Ph) chromosome). Although not frequently occurring, additional chromosome abnormalities (ACAs) can be detected at diagnosis and a number have been associated with an adverse cytogenetic and molecular outcome. The present study reports a case of CML presenting with the translocation t(1;11)(q21;q23) and a cryptic Ph chromosome. The presence of ACAs could generate greater genetic instability, promoting the emergence of further alterations. The present findings suggest that t(1;11)(q21;q23) can prevent a good response to tyrosine kinase inhibitor (TKI) therapy developing a primary resistance. In the present patient, at a recent follow-up, the T315I mutation was detected. This mutation confers full resistance to all available TKI, except ponatinib, which was not a therapeutic option due to comorbidities.

Enhancing acute myeloid leukemia therapy - monitoring response using residual disease testing as a guide to therapeutic decision-making

INTRODUCTION

Current standards for monitoring the response of acute myeloid leukemia (AML) are based on morphologic assessments of the bone marrow and recovery of peripheral blood counts. A growing experience is being developed to enhance the detection of small amounts of AML, or minimal residual disease (MRD). Areas covered: Available techniques include multi-color flow cytometry (MFC) of leukemia associated immunophenotypes (LAIP), quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) for detecting fusion and mutated genes (RUNX1-RUNX1T1, CBFB-MYH11, and NPM1), overexpression of genes such as WT1, and next generation sequencing (NGS) for MRD. Expert commentary: While MRD monitoring is standard of care in some leukemia subsets such as acute promyelocytic leukemia, this approach for the broader AML population does not universally predict outcomes as some patients may experience relapse in the setting of undetectable leukemia while others show no obvious disease progression despite MRD positivity. However, there are instances where MRD can identify patients at increased risk for relapse that may change recommended therapy. Currently, prospective investigations to define clinically relevant MRD thresholds are ongoing. Risk-adapted trials are needed to best define the use of MRD in the follow up of AML patients after initial induction therapy.