Characterizing of Four Common BCR-ABL Kinase Domain Mutations (T315I, Y253H, M351T and E255K) in Iranian Chronic Myelogenous Leukemia Patients With Imatinib Resistance

Occurrence of Existing BCR-ABL Baseline Mutations and Associated Haplotype (NmR) Among CML Patients with Diverse IM Response: A Hospital-based Study from North-East India

Highly polymorphic BCR-ABL kinase domains have been reported to harbor more than a hundred mutations, and among these, 40-60% have been identified as influencers of imatinib mesylate (IM) resistance. The emergence of IM resistance poses a significant challenge in the management of Chronic Myeloid Leukemia (CML). M351T (rs121913457), E255K (rs387906517), and Y253H (rs121913461) are of particular clinical significance due to their association with high-level imatinib resistance. This study was conducted to investigate the potential role of three significant SNPs in CML progression due to IM resistance. During the study period from 2018 to 2022 (48 months), the blood samples from 219 Reverse transcriptase-PCR-confirmed CML patients following RNA extraction and cDNA preparation were subjected to M351T, E255K, and Y253H mutation analysis by PCR-RFLP. After agarose gel visualization, the samples were subjected to Sanger sequencing to confirm the nucleotide change at the polymorphic loci. The wild-type genotype of all three ABL1 SNPs under investigation exhibits a significant reduction in frequency among IM non-responders compared to the responder group. The CGT haplotype frequency exhibits a significant difference between IM responder (4.2%) and non-responder (11.8%) (p = 0.002 < 0.05). Further, CGC haplotype was observed solely among the imatinib non-responder patients with a frequency percentage of 3.3% (p = 0.004), whereas the said genotype was absent among the responder group. A reduced overall survival rate was observed with deviation from wild-type genotype (M351T loci (T > C) with 1.217 times, E255K (G > A) with 1.485 and Y253H (T > C) with 1.399 times increase in hazard ratio) thereby enhancing mortality risk due to disease progression. The significant increase in the frequency of M351T, E255K, and Y253H loci among the IM non-responder group indicated their probable association with the development of IM resistance among CML patients. A haplotype frequency distribution pattern analysis of ABL1 loci further identified the CGC haplotype as an independent predictor for IM resistance. As such the study highlights the importance of patient characteristics, genotype distribution, and haplotype frequency distribution in predicting the response to IM treatment and clinical outcomes of CML patients.

Epigenetic Modulation of DDIT3 and MGMT Expression Acts Synergistically with Resistance to Imatinib towards CML Disease Progression: A Hospital based Study

INTRODUCTION

Imatinib Mesylate is an authenticated drug that aids in the treatment of Chronic Myeloid Leukaemia and Philadelphia patients which is recognized as a BCR-ABL tyrosine kinase inhibitor. Indeed, DNA Methylation occupies a key role in the stability of chromosomes.

OBJECTIVE

Changes in the methylation status of genes may impart to the advancement of Chronic Myeloid Leukaemia. The present investigation aims to assess the role of expression analysis and methylation status of DDIT3 and MGMT genes in imatinib-resistant and nonresistant cases.

METHODS

The Imatinib resistance was screened through RFLP. In this case maximum number of patients were recorded in the chronic phase belonging to the age group 40-59 and the accelerated and blast phase is more common in elderly patients showing the progressive nature of the disease with age. Hemoglobin and platelet count are found to be higher in cases where WBC count was minimal. A history of long-term alcohol consumption is found to be associated with the progression of the disease.

RESULTS

The maximum level of expression of the DDIT3 gene was recorded in the chronic phase regardless of upstream (67.8%) and downstream (57.9%) regulation. The highest MGMT expression regulation was also observed in the case of chronic phase in both upstream (78.9%) and downstream (44%) regulation. Further, the MGMT gene showed the highest methylation of 6.6% and DDIT3 showed 3.3% in CML cases.

CONCLUSION

In the present study notable depletion of survivality was established in the Imatinib resistance patients manifesting genetic malfunction of BCR-ABL transcripts among the North East Indian inhabitants and advocating for the expansion of the disease.

Differences in Variants in the Structural Domain of BCR-ABL1 Kinase between Chinese Han and Minority Patients with Chronic Myeloid Leukemia by Sanger Sequencing and Next-Generation Sequencing

This study aimed to detect differences in BCR-ABL1 kinase domain (KD) variants in patients with chronic myeloid leukemia (CML) who have been warned and failed in tyrosine kinase inhibitor (TKI) treatment among Chinese Han and ethnic minorities through Sanger sequencing (SS) and next-generation sequencing (NGS), and analyze the difference between SS and NGS detection. Peripheral blood samples from 51 CML patients with warning and failure of TKI therapy were analyzed using SS and NGS, and the detection differences between both sequencing types were compared. BCR-ABL1 KD variants were found in 23.53% of the cohort, including 7 Han Chinese (58.33%) and 5 ethnic minority cases (41.67%). Y253H, F317L, M244V, D276G, F359I, L387F, E459K, E255K, T315I, M351V, and heterozygous insertional mutated genes (ABL1 c.1068_1070dup) were detected. Comparison of the two sequencing assays revealed that NGS could detect compound variants and low frequency variants that were not detected by SS. More compound variants were detected in Han patients than in ethnic minority patients. In conclusion, there is no significant difference in BCR-ABL1 KD mutations between Han and ethnic minority patients. NGS has a higher mutation detection rate than SS, and can detect compound variants and genes with lower mutation frequency that are not detected by SS.

Imatinib Efficacy, Safety and Resistance in Iranian Patients with Chronic Myeloid Leukemia: A Review of Literature

Background: Imatinib is the gold standard in the treatment of chronic myeloid leukemia (CML) patients. Resistance to imatinib is interfering with patients’ responses and their survivals.

Materials and Methods: We designed a systematic search to find relevant studies by applying appropriate keywords in PubMed, Web of science, Scopus, Ovid, ProQuest, Science direct and Google scholar for English studies. We also investigated the aforementioned terms’ correspondence in Magiran, Scientific information database (SID) and Google scholar for Persian articles.

Results: 25 studies were selected for final analysis. Reported hematologic responses from adult studies ranged 86-99% and major molecular responses were estimated in 38.84% of our patients within 12 months of treatment. The most frequent reported adverse drug reactions (ADRs) were edema (n=5 studies, 100%) and fatigue and nausea (n=4 studies, 80%); ADR per capita ratio was 1.46. Only one study informed ADRs in pediatrics demonstrating 93% of patients experienced ADRs after receiving imatinib. Most of the Studies (n=4, 67% from 7 studies) considered BCR/ABL point mutation as main reason of imatinib resistance. Drug-binding site and P-loop regions were two common sites for BCR/ABL point mutation.

Conclusion: Imatinib as the first line treatment for CML has been associated with proper and durable responses in Iranian adults and children CML patients. Moreover, Imatinib life-threatening adverse effects were reported uncommon. Various responses to modified regimens have been reported in resistant patients; therefore, individualized treatment based on mutation type could be recommended.

ABL Kinase Domain Mutations in Iranian Chronic Myeloid Leukemia Patients with Resistance to Tyrosine Kinase Inhibitors

OBJECTIVE

Tyrosine kinase inhibitors (TKIs) are considered standard first-line treatment in patients with chronic myeloid leukemia. Because ABL kinase domain mutations are the most common causes of treatment resistance, their prevalence and assessment during treatment may predict subsequent response to therapy.

METHODS

The molecular response in Bcr-Abl1IS was tested via quantitative real-time polymerase chain reaction. We used the direct sequencing technique to discover the mutations in the ABL kinase domain. The IRIS trial established a standard baseline for measurement - (100% BCR-ABL1 on the 'international scale') and a major molecular response (good response to therapy) was defined as a 3-log reduction in the amount of BCR-ABL1 - 0.1% BCR-ABL1 on the international scale.

RESULTS

We observed 11 different mutations in 13 patients, including E255K, which had the highest mutation rate. A lack of hematologic response was found in 22 patients, who showed a significantly higher incidence of mutations.

CONCLUSION

Detection of kinase domain mutations is a reliable method for choosing the best treatment strategy based on patients' conditions, avoiding ineffective treatments, and running high-cost protocols in patients with acquired resistance to TKIs.

Induction of K562 Cell Apoptosis by As4S4 via Down-Regulating miR181

Background

Chronic myelogenous leukemia (CML) has unsatisfactory treatment efficacy at present. As the major component of red orpiment, tetra-arsenic tetra-sulfide (As₄S₄) has been recently used in treating leukemia, but with unclear mechanism targeting CML. MicroRNA (miR) is a group of endogenous non-coding RNAs regulating pathogenesis. MiR181 has been shown to exert important roles in tumor progression. The relationship between miR181 and As₄S₄ in inducing K562 cell apoptosis, however, is still unclear.

Material/Methods

CML cell line K562 was cultured in vitro in a control group and in groups receiving various dosages (20 μM and 40 μM) of As₄S₄. MTT assay was employed to detect the effect on K562 cell survival. MiR181 expression was quantified by real-time PCR. MTT assay and assay kit were used to determine K562 cell survival and caspase 3 expression. Cell apoptosis was assessed by flow cytometry. Bcl-2 expression was determined by real-time PCR and Western blotting.

Results

As₄S₄ significantly suppressed proliferation of K562 cells (p<0.05) and decreased miR181 expression, and increased caspase3 activity compared to the control group. It can induce K562 cell apoptosis via remarkably down-regulating mRNA and protein expressions of Bcl-2 (p<0.05).

Conclusions

As₄S₄ can facilitate K562 cell apoptosis via down-regulating miR181, inhibiting Bcl02 expression, and enhancing apoptotic protein caspase3 activity.

Effects of Two Common Promoter Polymorphisms of Transforming Growth Factor-β1 on Breast Cancer Risks in Ahvaz, West South of Iran

BACKGROUND

Transforming growth factor-β1 (TGF-β1) has a critical role in breast cancer initiation and progression.

OBJECTIVES

We have investigated the possible differences in two promoter polymorphisms (-509C/T and -800G/A) of TGF-β1 gene between breast cancer cases and controls.

PATIENTS AND METHODS

A total of 100 patients with confirmed breast cancer and 100 subjects without breast cancer was selected. Two promoter polymorphisms (-509C/T and -800G/A) of TGF-β1 gene were genotyped using PCR-based restriction fragment length polymorphism (RFLP) method.

RESULTS

The allele frequencies were 63% for C allele and 37% for T allele of SNP -509C/T and 66% for G allele and 34% for A allele of SNP -800G/A. Although no significant difference has observed between two groups, according to the genotype distribution, However, the TT genotype of -509 and AA genotype of -800 was significantly associated with breast cancer risk [odds ratio (OR) = 2.409; 95% confidence interval (CI) = 1.087 - 5.337, P = 0.030; and OR = 2.383; CI = 1.039 - 5.40, P = 0.040, respectively]. In addition, a multinomial logistic regression model shown, homozygous of -800 G/A (OR = 0.570; 95% CI = 0.362 - 0.896, P = 0.015); and HDL-C (OR = 0.935; 95% CI = 0.906 - 0.965, P < 0.001) were the selected variables associated with the presence of breast cancer. Haplotype analysis has shown no significant association between TGF-β1 haplotypes and breast cancer risk.

CONCLUSIONS

Our results indicated that among two promoter polymorphisms of the TGF-β1gene, -800G/A compared to -509C/T is more associated with breast cancer.

New Developments in Chronic Myeloid Leukemia: Implications for Therapy

Context:

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by overproduction of immature and matured myeloid cells in the peripheral blood, bone marrow and spleen.

Evidence Acquisition:

A hallmark of CML is the presence of (9; 22) (q34; q11) reciprocal translocation, which is cytogenetically visible as Philadelphia chromosome (Ph) and results in the formation of BCR-ABL1 fusion protein. This fusion protein is a constitutively active tyrosine kinase which is necessary and sufficient for malignant transformation. The introduction of imatinib, a BCR-ABL1- targeting tyrosine kinase inhibitor (TKI) has revolutionized CML therapy. Subsequently, two other TKIs with increased activity against BCR-ABL1, dasatinib and nilotinib, were developed and approved for CML patients. Nevertheless, CML therapy faces major challenges.

Results:

The first is the development of resistance to BCR-ABL1 inhibitors in some patients, which can be due to BCR-ABL1 overexpression, differences in cellular drug influx and efflux, activation of alternative signaling pathways, or emergence of BCR-ABL1 kinase domain mutations during TKI treatment. The second is the limited efficiency of BCR-ABL1-TKIs in blast crisis (BC) CML. The third is the insensitivity of CML stem cells to BCR-ABL1 inhibitors. Conventional chemotherapeutics and BCR-ABL1 inhibitors which act by inhibiting cell proliferation and inducing apoptosis, are ineffective against quiescent CML stem cells.

Conclusions:

A better understanding of the mechanisms that underlie TKI resistance, progression to BC, genomic instability and stem cell quiescence is essential to develop curative strategies for patients with CML.