Additional chromosome abnormalities, BCR-ABL tyrosine kinase domain mutations and clinical outcome in Hungarian tyrosine kinase inhibitor-resistant chronic myelogenous leukemia patients

A customized mass array panel for BCR::ABL1 tyrosine kinase domain mutation screening in chronic myeloid leukemia

Introduction

The therapeutic strategy and management of chronic myeloid leukemia (CML) have rapidly improved with the discovery of effective tyrosine kinase inhibitors (TKIs) to target BCR::ABL1 oncoprotein. However, nearly 30% of patients develop TKI resistance due to acquired mutations on the tyrosine kinase domain (TKD) of BCR::ABL1.

Methods

We customized a mass array panel initially intended to detect and monitor the mutational burden of hotspot BCR::ABL1 TKD mutations accumulated in our database, including key mutations recently recommended by European LeukemiaNet. Additionally, we extended the feasibility of using the assay panel for the molecular classification of myeloproliferative neoplasms (MPNs) by incorporating primer sets specific for analyzing JAK2 V617F, MPL 515 K/L, and CALR types 1 and 2.

Results

We found that the developed mass array panel was superior for detecting and monitoring clinically significant BCR::ABL1 TKD mutations, especially in cases with low mutational burden and harboring compound/polyclonal mutations, compared with direct sequencing. Moreover, our customized mass array panel detected common genetic alterations in MPNs, and the findings were consistent with those of other comparable assays available in our laboratory.

Conclusions

Our customized mass array panel was practicably used as a routine robust assay for screening and monitoring BCR::ABL1 TKD mutations in patients with CML undergoing TKI treatment and feasible for analyzing common genetic mutations in MPNs.

Activation of ERK1/2 by MOS and TPL2 leads to dasatinib resistance in chronic myeloid leukaemia cells

The development of BCR::ABL1 tyrosine kinase inhibitors (TKIs), such as dasatinib, has dramatically improved survival in cases of chronic myeloid leukaemia (CML). However, the development of resistance to BCR::ABL1 TKIs is a clinical problem. BCR::ABL1 TKI resistance is known to have BCR::ABL1-dependent or BCR::ABL1-independent mechanisms, but the mechanism of BCR::ABL1 independence is not well understood. In the present study, we investigated the mechanism of BCR::ABL1-independent dasatinib resistance. The expression and activation level of genes or proteins were evaluated using array CGH, real time PCR, or western blot analysis. Gene expression was modulated using siRNA-mediated knockdown. Cell survival was assessed by using trypan blue dye method. We found that dasatinib-resistant K562/DR and KU812/DR cells did not harbour a BCR::ABL1 mutation but had elevated expression and/or activation of MOS, TPL2 and ERK1/2. In addition, MOS siRNA, TPL2 siRNA and trametinib resensitized dasatinib-resistant cells to dasatinib. Moreover, expression levels of MOS in dasatinib non-responder patients with CML were higher than those in dasatinib responders, and the expression of TPL2 tended to increase in dasatinib non-responder patients compared with that in responder patients. Our results indicate that activation of ERK1/2 by elevated MOS and TPL2 expression is involved in dasatinib resistance, and inhibition of these proteins overcomes dasatinib resistance. Therefore, MOS, TPL2 and ERK1/2 inhibitors may be therapeutically useful for treating BCR::ABL1-independent dasatinib-resistant CML.

Chronic Myeloid Leukemia, from Pathophysiology to Treatment-Free Remission: A Narrative Literature Review

Chronic myeloid leukemia (CML) is one of the most common leukemias occurring in the adult population. The course of CML is divided into three phases: the chronic phase, the acceleration phase, and the blast phase. Pathophysiology of CML revolves around Philadelphia chromosome that constitutively activate tyrosine kinase through BCR-ABL1 oncoprotein. In the era of tyrosine kinase inhibitors (TKIs), CML patients now have a similar life expectancy to people without CML, and it is now very rare for CML patients to progress to the blast phase. Only a small proportion of CML patients have resistance to TKI, caused by BCR-ABL1 point mutations. CML patients with TKI resistance should be treated with second or third generation TKI, depending on the BCR-ABL1 mutation. Recently, many studies have shown that it is possible for CML patients who achieve a long-term deep molecular response to stop TKIs treatment and maintain remission. This review aimed to provide an overview of CML, including its pathophysiology, clinical manifestations, the role of stem cells, CML treatments, and treatment-free remission.

Chronic myeloid leukemia: cytogenetics and molecular biology’s part in the comprehension and management of the pathology and treatment evolution

Background

Chronic myelogenous leukemia (CML) is a type of blood cancer that affects hematopoietic stem cells and is often characterized by the presence of the Philadelphia chromosome. The Philadelphia chromosome encodes for a protein with high tyrosine kinase activity which acts as a tumorigenic factor.

Main body

This review article reports an update on the pathophysiology of CML and highlights the role of cytogenetic and molecular biology in screening, diagnosis, therapeutic monitoring as well as evaluating patients’ response to treatment. Additionally, these genetic tests allow identifying additional chromosomal abnormalities (ACA) and BCR-ABL tyrosine kinase domain mutations in intolerant or resistant patients. Thus, therapeutic advances have enabled this pathology to become manageable and almost curable in its clinical course. The scientific literature search used in the synthesis of this paper was carried out in the PubMed database, and the figures were generated using online software named BioRender.

Conclusion

The role of cytogenetic and molecular biology is crucial for the diagnosis and medical monitoring of patients. In-depth knowledge of molecular mechanisms of the BCR-ABL kinase facilitated the development of new targeted therapies that have improved the vital prognosis in patients. However, the emergence of ACA and new mutations resistant to tyrosine kinase inhibitors constitutes a real challenge in the quest for adequate therapy.

Practical Laboratory Tools for Monitoring of BCR-ABL1 Transcripts and Tyrosine Kinase (TK) Domain Mutations in Chronic Myeloid Leukemia Patients Undergoing TK Inhibitor Therapy: A Single-Center Experience in Thailand

Objective:

The genetic hallmark of CML is known as the appearance of t(9;22)(q34.1;q11.2) (BCR-ABL1) which is present in more than 95% of cases. Here, we demonstrated practical laboratory tools for monitoring of BCR-ABL1 transcripts in chronic myeloid leukemia patients undergoing TK inhibitor therapy.

Methods:

Real time quantitative PCR and direct sequencing were performed for monitoring of BCR-ABL1 transcripts in 245 treated CML.

Results:

At month 3 after first time point of monitoring, we found that 89% (218/245), 2% (5/245), and 9% (22/245) of patients are determined as optimal, warning, and failure response, respectively. The responses to TKI were slightly decreased at months 6 as following 73% optimal (180/245), 18% warning (43/245), and 9% failure response (22/245). Additionally, responses to TKI were gradually decreased at month 12 after first time point of monitoring as following 65% optimal (160/245), 13% warning (31/245), and 22% failure (54/245). We could detect 20% (49/245) of patients positive for BCR-ABL1 TKD mutations. Interestingly, one third (17 of 49) of TKD mutated cases were positive for compound/polyclonal mutation patterns. While major molecular response were observed in the majority of patients without TKD mutation, resistant to TKI were detected in patients with T315I mutation (n = 9; % mean IS = 8.1510, % median IS = 9.7000), compound/polyclonal mutations with T315I (n = 9; % mean IS = 13.0779, % median IS = 5.404), and other TKD mutations (n = 14; % mean IS = 8.1416, % median IS = 1.060), respectively.

Conlusion:

These practical laboratory techniques provided a more comprehensive understanding of CML progression during drug therapy and could be of benefit in earlier prognosis.

T-cell blast crisis of chronic myelogenous leukemia presented with coexisting p210 and p190 BCR-ABL transcripts and t(10;11)(q11;p15)

Background

Blast transformation of chronic myelogenous leukemia (CML) to T lymphoblastic lymphoma/acute lymphoblastic leukemia (T‐LBL/ALL) is rare, and the molecular mechanism is still unclear.

Case report

A 28‐year‐old woman who developed T‐ALL with coexpressing both p210 and p190 BCR‐ABL transcripts five years after the initial diagnosis of CML in chronic phase. The proliferation of bone marrow was extremely active with blast cells over 20%. Chromosome analysis revealed t(9;22)(q34;q11) and t(10;11)(q25;p15). Flow immunophenotyping showed that blasts expressed CD4, CD7, CD11b, CD38, CD34, CD33, and cCD3.

Conclusion

It is the first T‐cell blast of CML case with coexisting p210 and p190 as well as additional chromosome translocations. Through review this case and previous reports, we will reveal that CML patients with T‐lymphocyte transformation depend on potential molecular and pathological mechanism.

Outcomes of 219 chronic myeloid leukaemia patients with additional chromosomal abnormalities and/or tyrosine kinase domain mutations

INTRODUCTION

To confirm the role of additional chromosomal abnormalities (ACAs) and kinase domain (KD) mutations in the progression and outcomes of Chronic myeloid leukaemia (CML) patients and the connection between them, we analysed the ACAs and KD mutations of 219 CML patients admitted to our hospital.

METHODS

Cytogenetic analysis of metaphases was performed to detect ACAs, and the BCR-ABL1 KD was sequenced to detect KD mutations.

RESULTS

Twenty-four patients (11.0%) had ACAs in addition to the BCR-ABL1 or t(9;22)(q34;q11) translocation. The most common abnormality was trisomy 8. Twelve different KD mutations were observed in 13 out of 53 imatinib-resistant patients (24.5%). p.(Y235H) (n = 3; 23.07%), p.(F359V) and p.(T315I) (n = 2; 15.38%) presented most frequently. KD mutations subtypes (p.(E255K), p.(T315I), p.(F359V), p.(M244V) and p.(L298V)) coexisted with ACAs. The incidence of CML progression was 12/22 (54.5%) in the group of patients with ACAs and/or KD mutations and 2/143 (1.4%) in the group of patients without ACAs or KD mutations (CI 95%, P < 0.001) and was higher in the KD mutations group than in the ACAs group (P = 0.046). The group of patients with ACAs and/or KD mutations had more men than the group of patients without ACAs or KD mutations (P = 0.013).

CONCLUSION

We conclude that ACAs and/or KD mutations are related to CML progression and are adverse outcome factors. Their presence exhibits gender differences and is more common in males. p.(E255K), p.(T315I), p.(F359V), p.(M244V) and p.(L298V) emerge more frequently when ACAs and KD mutations coexist.

Recurrent chronic myeloid leukemia with t (9;22;16) (q34; q11; p13) treated by nilotinib: A case report

RATIONALE

Variant Philadelphia chromosome translocations involving chromosomes other than chromosomes 9 and 22 have been reported in 5% to 10% of patients with chronic myeloid leukemia (CML). Here, a case of CML with a t (9, 22, 16) (q34; q11; p13) translocation, which has never been described, is reported.

PATIENT CONCERNS

A 59-year-old female with dry cough, referred to our hospital, exhibited hepatosplenomegaly, high basophil count, and high platelet count at admission without any other known chronic diseases.

DIAGNOSES

The patient was diagnosed with CML with the translocation t (9;22;16) (q34; q11; p13). The patient was treated with imatinib, a first-generation tyrosine kinase inhibitor (TKI), discontinuously, achieving a complete hematological response for 7 years. Since November 8, 2017, the patient had recurrent fever, and her platelet count rose to 1422 × 10/L. Subsequently, the E279K mutation in the BCR-ABL kinase region was detected.

OUTCOMES

According to a previous report, this mutation confers sensitivity to nilotinib, a second-generation TKI. In the end, the patient received treatment with nilotinib and showed a complete hematological response.

LESSONS

The present study reports a rare case of CML with Ph chromosome and a t (9;22;16) (q34; q11; p13) translocation. For such cases about CML with variant Philadelphia chromosome translocations or BCR-ABL kinase region mutation, TKI may still be valuable.

[The molecular-cytogenetic characterization and tyrosine kinase inhibitors efficacy in newly diagnosed chronic phase CML patients with variant Philadelphia chromosomes]

Objective: To investigate the molecular-cytogenetic characterization and impact on tyrosine kinase inhibitors (TKIs) therapy in chronic phase of chronic myeloid leukemia (CML-CP) patients with variant Ph chromosome (vPh). Methods: The clinical data of 32 patients with vPh chromosomes were collected and compared with 703 patients with typical Ph chromosome in newly diagnosed CML-CP who were on first-line imatinib (IM) and with BCR-ABL transcript of P210. Results: There was no significant difference in demographic and hematological characteristics between vPh and classic Ph patients. 3(9.4%) of the 32 vPh cases were simple variant translocations. Among the remaining 29 cases with complex variant translocations, 28 cases (87.5%) involved 3 chromosomes, and only 1 (3.1%) involved 4 chromosomes. Except for 8, 15, 18, X, and Y chromosomes, the other chromosomes were involved. The frequency of chromosome 12q(15.5%) and 1p (12.1%) were higher involved. The most common FISH signal pattern was 2G2R1Y (74.1%), followed by 1G1R2F (14.8%), 2G1R1Y (3.7%), 1G2R1Y (3.7%), 1G1R1Y (3.7%). The comparison of complete cytogenetic response (CCyR) (P=0.269), major molecular response (MMR) (P=0.391) were carried out between simple and complex mechanisms, without difference. Compared with the classic Ph, the patients with vPh had higher IM primary resistance rate (χ2=3.978, P=0.046), especially primary hematological resistance (χ2=7.870, P=0.005), but the difference of CCyR (χ2=0.192, P=0.661), MMR (χ2=0.822, P=0.365), EFS (χ2=0.509, P=0.476), OS (χ2=3.485, P=0.062) were not statistically significant, and multivariate analysis showed that the presence of vPh did not affect OS (RR=0.692, 95%CI 0.393-1.765, P=0.658)、EFS (RR=0.893, 95%CI 0.347-2.132, P=0.126) and PFS (RR=1.176, 95%CI 0.643-2.682, P=0.703). Conclusion: CML-CP patients with vPh and classic Ph had similar demographic and hematological characteristics. Except for 22q11, 9q34, the frequency of chromosome 12q and 1p were higher involved. The most common FISH signal pattern was 2G2R1Y, and different mechanisms had no impact on TKIs therapy. Compared with cases with classic Ph chromosomes, the patients with vPh chromosomes had higher risk of IM primary resistance, especially primary hematological resistance, which can obtain deeper molecular response quickly after changing to second-generation TKIs and didn't affect long-term outcomes and OS.

Metal chelator TPEN selectively induces apoptosis in K562 cells through reactive oxygen species signaling mechanism: implications for chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a hematologic disorder characterized by the constitutive expression of BCR-ABL tyrosine kinase. Although successful implementation of tyrosine kinase inhibitors for the treatment of CML remain a traditional choice for molecularly targeted therapy, some patients present primary or secondary resistance to such therapy. Therefore, alternative therapeutic strategies are required to treat resistant CML cells. Accordingly, new anti-proliferative and/or pro-apoptotic compounds would be needed for clinical treatment. In the present investigation, we demonstrate that TPEN (e.g. 3 μM), a lipid-soluble metal chelator, induces apoptosis in K562 cells via a molecular cascade involving H₂O₂ ≫ JNK, NF-κB > c-JUN, P73 > PUMA, BAX > loss of ΔΨ_m > CASPASE-3 > nuclei/DNA fragmentation. Fragmentation of the nuclei and DNA are indicative of cell death by apoptosis. Remarkably, the antioxidant N-acetyl-cysteine, and inhibitors of the transcription factors CASPASE 3 and (JNK) kinase, decreased oxidative stress (OS) and cell death in these cells. This is evidenced by fluorescence microscopy, flow cytometry and immunocytochemistry for OS markers (e.g. generation of H₂O₂ and DJ 1 oxidation) and nuclear expression of apoptotic markers (e.g. activated caspase 3 and JNK kinase). In addition, TPEN causes no detectable damage in human peripheral blood lymphocyte cells (hPBLCs). We conclude that TPEN selectively induces apoptosis in K562 cells via an OS-mechanism. Our findings may provide insight into more effective CML anticancer therapies.

[Current diagnostic requirements in chronic myeloid leukemia]

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

Implications of BCR-ABL1 kinase domain-mediated resistance in chronic myeloid leukemia

Patients with chronic myeloid leukemia develop resistance to both first-generation and second-generation tyrosine kinase inhibitors (TKIs) as a result of mutations in the kinase domain (KD) of BCR-ABL1. A wide range of BCR-ABL1 KD mutations that confer resistance to TKIs have been identified, and the T315I mutant has proven particularly difficult to target. This review summarizes the prevalence, impact, and prognostic implications of BCR-ABL1 KD mutations in patients with chronic myeloid leukemia who are treated with current TKIs and provides an overview of recent treatment guidelines and future trends for the detection of mutations.

Imatinib Mesylate Effectiveness in Chronic Myeloid Leukemia with Additional Cytogenetic Abnormalities at Diagnosis among Black Africans

Imatinib mesylate provides good results in the treatment of CML in general. But what about the results of this treatment in CML associated with additional cytogenetic abnormalities at diagnosis among black Africans? For this, we retrospectively studied 27 cases of CML associated with additional cytogenetic abnormalities, diagnosed in the department of clinical hematology of the University Hospital of Yopougon in Côte d'Ivoire, from May 2005 to October 2011. The age of patients ranged from 13 to 68 years, with a mean age of 38 years and a sex ratio of 2. Patients were severely symptomatic with a high Sokal score of 67%. CML in chronic phase accounted for 67%. The prevalence of additional cytogenetic abnormalities was 29.7%. There were variants of the Philadelphia chromosome (18.5%), trisomy 8 (14.8%), complex cytogenetic abnormalities (18.5%), second Philadelphia chromosome (14.8%), and minor cytogenetic abnormalities (44.4%). Complete hematologic remission was achieved in 59%, with 52% of major cytogenetic remission. The outcome was fatal in 37% of patients. Death was related in 40% to hematologic toxicity and in 30% to acutisation. The median survival was 40 months.

Polymorphic variation in glutathione-S-transferase genes and risk of chronic myeloid leukaemia in the Kashmiri population

Cancer is a complex disease and the genetic susceptibility to it could be an outcome of the inherited difference in the capacity of xenobiotic metabolizing enzymes. Glutathione-S-transferases (GSTs) are phase II metabolizing enzymes whose various genotypes have been associated with increased risk of different types of cancer. Null mutations caused by the deletion of the entire gene result in the absence of the enzymatic activity and increase in the risk of developing cancer including chronic myeloid leukaemia (CML). In the present case-control study we evaluated the effect of null mutations in GSTM1 and GSTT1 genes on the risk of developing CML. The study included 75 CML patients (43 males and 32 females; age (mean ± S.D) 42.3 ± 13.4 years) and unrelated non-malignant controls (76 male and 48 females; age (mean ± S.D) 41.5 ± 12.9). The distribution of GSTM1 and GSTT1 genotypes in CML patients and controls was assessed by multiplex-PCR method. Logistic regression was used to assess the relationship between GSTM1 and GSTT1 genotypes and risk of CML. Chi-square test was used to evaluate the trend in modulating the risk to CML by one or more potential high risk genotype. Although GSTM1 null genotype frequency was higher in CML patients (41%) than in the controls (35%), it did not reached a statistical significance (OD = 1.32, 95% CI: 0.73-2.40; P value = 0.4295). The frequency of GSTT1 null genotypes was higher in the CML patients (36%) than in the controls (21%) and the difference was found to be statistically significant (OD = 2.12, 95% CI: 1.12-4.02; P value = 0.0308). This suggests that the presence of GSTT1 genotype may have protective role against the CML. We found a statistically significant (OD = 3.09, 95% CI: 1.122-8.528; P value = 0.0472) interaction between the GSTM1 and GSTT1 null genotypes and thus individuals carrying null genotypes of both GSTM1 and GSTT1 genes are at elevated risk of CML.