Breakpoint Cluster Region Gene Research Articles

Chronic myeloid leukemia: 2025 update on diagnosis, therapy, and monitoring.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an annual incidence of two cases/100 000. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults. CML is characterized by a balanced genetic translocation, t(9;22) (q34;q11.2), involving a fusion of the Abelson murine leukemia (ABL1) gene from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR::ABL1 fusion oncogene, which in turn translates into a BCR::ABL1 oncoprotein. Four tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, bosutinib, and nilotinib, are approved by the United States Food and Drug Administration (FDA) for first-line treatment of newly diagnosed CML in the chronic phase (CML-CP). Clinical trials with second and third-generation TKIs in frontline CML-CP therapy reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of their potent efficacy and the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy. All four TKIs are equivalent if the aim of therapy is to improve survival. In younger patients with high-risk disease and in whom the aim of therapy is to induce a treatment-free remission status, second-generation TKIs may be favored. For CML post-failure on frontline therapy, second-line options include second and third-generation TKIs. Although potent and selective, these TKIs exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities and financial status, disease stage, and BCR::ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib, asciminib, and olverembatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP and failure (due to resistance) of at least two TKIs and for all patients in advanced-phase disease. Older patients who have a cytogenetic relapse post-failure on all TKIs can maintain long-term survival if they continue a daily most effective/least toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, and others).

Genç Yaşta Görülen Transizyonel Hücreli Mesane Karsinomunda Genetik Yatkınlık Var Mıdır?

Objective: The aim of this study is to determine whether there is a genetic predisposition in young patients with transitional cell carcinoma (TCC) of the bladder. Material And Methods: Data were collected from a total of 652 patients who underwent transurethral resection of bladder tumor (TUR-BT) between January 2010 and January 2021. Seven patients under the age of 40, non-smokers, and without occupational predisposing factors to urinary tract TCC were included in the study. Age, body mass index (BMI), sex, occupation, and five-year follow-up were collected retrospectively. A total of 403 cancer-related genes were analyzed from the patients’ blood samples. The Clinical Exome Sequencing test was used to identify genetic mutations. Results: Six of the patients were male and one patient was female. The mean age and BMI were 31.42 ± 2.12 (22-39) years and 21.72 ± 33.14 (22-27.7) kg/m2, respectively. None of the patients had a first-degree relative with urinary tract TCC. Of all the patients, only one patient had a deletion of exons 1 to 17 in the breakpoint cluster region gene. Conclusion: Genetic predisposing factors in young bladder TCC have not been clearly identified. Although our study included a limited number of patients, our results showed no genetic predisposition in young patients with bladder TCC without family history of bladder cancer. To evaluate the exact relationship, prospective randomised controlled trials with larger numbers of patients are needed.

Viral Infections and Reactivations in Chronic Myeloid Leukemia Patients on Tyrosine Kinase Inhibitors (TKIs)

Introduction Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm characterized by the unregulated growth of myeloid cells, resulting in a proliferation of mature granulocytes. The reciprocal translocation, which results from the fusion of the breakpoint cluster region (BCR) gene on 22q11.2 and the Abelson murine leukemia (ABL1) gene on 9q34.1 is the hallmark of the disease and results in a BCR/ABL1 fusion product with abnormal tyrosine kinase activity, which plays a role in the unregulated cell proliferation. CML accounts for 15-20% of adults leukemias. Tyrosine kinase inhibitors (TKI) have revolutionized the treatment of CML, as it is highly successful and has transformed the prognosis of patients with CML. However, TKIs may be associated with an increased risk of infections. This review highlights the risk of viral infections in patients with CML. Methodology We have performed a literature search for English language articles using PubMed, Scopus, and Google Scholar, for the period 2001-2022. And population consisted of patients over 18 years old with a diagnosis of CML and no history of BMT. Articles include case reports, case series, informative reviews, and clinical trials. The keywords were " CML, Chronic Myelogenous Leukemia, Viral, Infection." Search results were initially reviewed by title and abstract, and articles were selected for more in-depth analysis if deemed relevant. Pertinent articles were examined in-depth for this report. Results In an analysis of 41 patients, with 25 males and 16 females, M:F ratio of 1.56:1, and the median age of 50. Age ranged from 22 to 79 years. Most patients with reported viral infections or reactivations were in the chronic phase of CML, with 22 patients (76%) in the chronic phase, 6 patients (21%) in the accelerated phase, and one patient (3%) in the blast phase. Most cases with reported outcomes responded to treatment to CML; only one had refractory disease, and 8 cases (32%) had Major molecular response. Imatinib was the most commonly used TKI in 30 patients (77%). The most commonly reported viral reactivations were Herpes zoster in 17 cases (41%), followed by Hepatitis B reactivation in 15 cases (37%). Conclusion Patients with a diagnosis of CML have a high risk for viral infections, mainly reactivation of latent viruses like varicella zoster and hepatitis B; this is likely because of the disease itself; adaptive immune responses are dysfunctional in CML patients at diagnosis before starting TKI treatment and before the progression to overt immune deficiency secondary to blastic transformation, as evident by the large number of patients having viral reactivation in the chronic phase; reasons included dysfunctional CD8+ cytotoxic T-cells (CTLs). On the other hand, treatment by TKI can increase this risk of viral reactivation; therapy with imatinib was associated with significant reductions in IgM memory B cells. This review shows the importance of having a hepatitis B serology checked before starting TKI therapy, close monitoring and clinical suspicions for viral infections or reactivations in patients with CML on TKIs; further clinical trials are needed to assess the need for viral prophylaxis for CML patients after starting TKIs. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Update in Childhood Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) in childhood represents only 3% of newly diagnosed pediatric leukemia. The diagnostic hallmark of CML is the Philadelphia (Ph) chromosome, which derives from the fusion of the ABL1-oncogene located on chromosome 9 to the breakpoint cluster region (BCR) gene on chromosome 22, resulting in a constitutively dysregulated ABL1 tyrosine kinase, either as 210 kDa or 190 kDa. Depending on the localization of the breakpoint site within the major BCR region, the majority of CML patients exhibit transcripts with either the b3a2 or b2a2 junction, or both. Several questions are still open with regard to childhood CML, especially concerning the biologic and clinical features of the disease, and the treatment of choice for pediatric patients with CML. Moreover, over the last few years, several tyrosine kinase inhibitors (TKIs) have been available for children and adolescents with CML, and current clinical practice investigates what the effective and optimal doses of TKIs are in these two categories of patients. The use of TKIs in pediatric patients with CML has also opened up questions on the following items: (1) the long-term effects of these drugs on children; (2) the management of pediatric CML forms resistant or intolerant to TKIs; (3) the monitoring of disease outcomes during treatment; (4) and the right timing to discontinue therapy. Despite the efficacy of TKIs also in the pediatric population, the potential late adverse effects, and the drug resistance, leave open the possibility of allogeneic hematopoietic stem cell transplantation as a treatment option in pediatric CML. Published data and personal experiences regarding these issues will be analyzed and discussed.

104P Development of a new generation of imatinib using structural biology techniques at ambient temperature

Chronic myeloid leukemia (CML) is a kind of blood cancer and most CML patients have associated with a chromosomal anomaly with the BCR-ABL fusion oncogene, which occurs as a result of translocation between the Abelson murine leukemia (ABL1) gene on chromosome 9 and breakpoint cluster region (BCR) gene on chromosome 22. Imatinib mesylate is the first small molecule developed to target the BCR-ABL fusion protein. Imatinib reduces BCR-ABL activity by binding to the inactive conformation of tyrosine kinases.

Chronic myeloid leukemia: 2022 update on diagnosis, therapy, and monitoring.

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100 000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults. CML is characterized by a balanced genetic translocation, t (9;22) (q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR::ABL1 fusion oncogene, which in turn translates into a BCR::ABL1 oncoprotein. Four tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, bosutinib, and nilotinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy. For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these TKIs exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR::ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib, asciminib, and olverembatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP and failure (due to resistance) of at least two TKIs, and for all patients in advanced phase disease. Older patients who have a cytogenetic relapse post failure on all TKIs can maintain long-term survival if they continue a daily most effective/least toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan and others).

MiR-125a-3p and MiR-320b Differentially Expressed in Patients with Chronic Myeloid Leukemia Treated with Allogeneic Hematopoietic Stem Cell Transplantation and Imatinib Mesylate.

Chronic myeloid leukemia (CML), a hematopoietic neoplasm arising from the fusion of BCR (breakpoint cluster region) gene on chromosome 22 to the ABL (Abelson leukemia virus) gene on chromosome 9 (BCR-ABL1 oncogene), originates from a small population of leukemic stem cells with extensive capacity for self-renewal and an inflammatory microenvironment. Currently, CML treatment is based on tyrosine kinase inhibitors (TKIs). However, allogeneic hematopoietic stem cell transplantation (HSCT-allo) is currently the only effective treatment of CML. The difficulty of finding a compatible donor and high rates of morbidity and mortality limit transplantation treatment. Despite the safety and efficacy of TKIs, patients can develop resistance. Thus, microRNAs (miRNAs) play a prominent role as biomarkers and post-transcriptional regulators of gene expression. The aim of this study was to analyze the miRNA profile in CML patients who achieved cytogenetic remission after treatment with both HSCT-allo and TKI. Expression analyses of the 758 miRNAs were performed using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Bioinformatics tools were used for data analysis. We detected miRNA profiles using their possible target genes and target pathways. MiR-125a-3p stood out among the downregulated miRNAs, showing an interaction network with 52 target genes. MiR-320b was the only upregulated miRNA, with an interaction network of 26 genes. The results are expected to aid future studies of miRNAs, residual leukemic cells, and prognosis in CML.

State of the Art in CML: Update

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1–1.2 cases per 100,000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults. CML is characterized by a balanced genetic translocation, t(9;22) (q34;q11.2), resulting in a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2 (Philadelphia chromosome, Ph). The molecular consequence of this translocation is the BCR-ABL1 oncogene, which translates into a BCR-ABL1 oncoprotein.

Identification of the motifs of beta-turns and mutated amino acids studies on BCR (Breakpoint cluster region) protein using Insilico techniques

Recent investigations have rapidly added crucial new insights into the complex functions of the normal BCR gene and of the BCR-ABL chimaera. They are yielding potential therapeutic breakthroughs in the treatment of Philadelphia (Ph) chromosome-positive leukemias. The objective of the present in silico research investigation is to find out whether the functional part (beta-turns) is present in the mutated amino acids of BCR (Breakpoint cluster region) protein. Two significant steps are involved in this study. First, we performed protein sequence modeling of BCR using automated protein modeling servers and the 3D structure was visualized using molecular visualization software and tools. In the second step, the function domains and motifs regions of BCR gene-coded protein is predicted using “PDBsum generate” tool in order to show where exactly the beta-turns lie on the clinically-proven mutated amino acids of BCR protein. The results of our investigation can be used as potential drug binding sites in the field of drug docking studies. It can act as a potential therapeutic agent for Chronic Myeloid Leukemia (CML) type of Leukemia.

Philadelphia Chromosome-Positive Leukemia in the Lymphoid Lineage-Similarities and Differences with the Myeloid Lineage and Specific Vulnerabilities.

Philadelphia chromosome (Ph) results from a translocation between the breakpoint cluster region (BCR) gene on chromosome 9 and ABL proto-oncogene 1 (ABL1) gene on chromosome 22. The fusion gene, BCR-ABL1, is a constitutively active tyrosine kinase which promotes development of leukemia. Depending on the breakpoint site within the BCR gene, different isoforms of BCR-ABL1 exist, with p210 and p190 being the most prevalent. P210 isoform is the hallmark of chronic myeloid leukemia (CML), while p190 isoform is expressed in majority of Ph-positive B cell acute lymphoblastic leukemia (Ph+ B-ALL) cases. The crucial component of treatment protocols of CML and Ph+ B-ALL patients are tyrosine kinase inhibitors (TKIs), drugs which target both BCR-ABL1 isoforms. While TKIs therapy is successful in great majority of CML patients, Ph+ B-ALL often relapses as a drug-resistant disease. Recently, the high-throughput genomic and proteomic analyses revealed significant differences between CML and Ph+ B-ALL. In this review we summarize recent discoveries related to differential signaling pathways mediated by different BCR-ABL1 isoforms, lineage-specific genetic lesions, and metabolic reprogramming. In particular, we emphasize the features distinguishing Ph+ B-ALL from CML and focus on potential therapeutic approaches exploiting those characteristics, which could improve the treatment of Ph+ B-ALL.

NHD2-15, a novel antagonist of Growth Factor Receptor-Bound Protein-2 (GRB2), inhibits leukemic proliferation.

The majority of chronic myeloid leukemia (CML) cases are caused by a chromosomal translocation linking the breakpoint cluster region (BCR) gene to the Abelson murine leukemia viral oncogene-1 (ABL1), creating the mutant fusion protein BCR-ABL1. Downstream of BCR-ABL1 is growth factor receptor-bound protein-2 (GRB2), an intracellular adapter protein that binds to BCR-ABL1 via its src-homology-2 (SH2) domain. This binding constitutively activates growth pathways, downregulates apoptosis, and leads to an over proliferation of immature and dysfunctional myeloid cells. Utilizing novel synthetic methods, we developed four furo-quinoxaline compounds as GRB2 SH2 domain antagonists with the goal of disrupting this leukemogenic signaling. One of the four antagonists, NHD2-15, showed a significant reduction in proliferation of K562 cells, a human BCR-ABL1+ leukemic cell line. To elucidate the mode of action of these compounds, various biophysical, in vitro, and in vivo assays were performed. Surface plasmon resonance (SPR) assays indicated that NHD2-15 antagonized GRB2, binding with a KD value of 119 ± 2 μM. Cellulose nitrate (CN) assays indicated that the compound selectively bound the SH2 domain of GRB2. Western blot assays suggested the antagonist downregulated proteins involved in leukemic transformation. Finally, NHD2-15 was nontoxic to primary cells and adult zebrafish, indicating that it may be an effective clinical treatment for CML.

Single nucleotide polymorphisms in tinnitus patients exhibiting severe distress

The association between distress caused by tinnitus and psychological factors such as depression and anxiety has been examined and reported. However, prognostic factors remain poorly understood because there are only a few reports on genetic associations. We theorized there might be an association between the grade of tinnitus distress and the genetic background related to psychological factors which might lead us to identify prognostic markers. We enrolled 138 patients who had suffered from tinnitus for over 3 months. Using Tinnitus Handicap Inventory (THI) scores, we examined the association between tinnitus distress and a genetic background related to depression or anxiety. A significant association between single nucleotide polymorphism rs131702 of the Breakpoint Cluster Region (BCR) gene and the severe THI score was identified. In addition, there was an association with the severity of the State-Trait Anxiety Inventory, an index of state anxiety severity. No association was found with the Self-Rating Depression Scale, an index of depression severity. It is reported that rs131702 of BCR in Japanese patients are related to bipolar II depression characterized by fluctuation between abnormal mood states of mania and depression. Our results indicate that rs131702 of BCR is independent of depression in this study and is, therefore, a prognostic factor unique to tinnitus. We conclude that the severity of tinnitus is associated with genes related to depression.

Chronic myeloid leukemia: 2020 update on diagnosis, therapy and monitoring.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100 000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults. CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL1 fusion oncogene, which in turn translates into a BCR-ABL oncoprotein. Four tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, dasatinib, and bosutinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses, but they had no impact on survival prolongation, likely because of the existence of highly effective salvage therapies for patients who have a cytogenetic relapse with frontline TKI. For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR-ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP who have failed at least 2 TKIs, and for all patients in advanced phase disease. Even among older patients who have a cytogenetic relapse post failure on all TKIs, they can maintain long-term survival if they continue on a daily most effective/less toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan, others).

Activation of AKT/mTOR Pathway in Ph+ Acute Lymphoblastic Leukemia (ALL) Leads to Non-Mutational Resistance

Introduction: The t(9;22) (q34;q11) translocation results in the constative active BCR/ABL tyrosine kinase. Der22 involves the Breakpoint Cluster Region (BCR) gene locus with two principal breaks: a. M-bcr, encoding for the p210-BCR/ABL and b. m-bcr, encoding for the p185-BCR/ABL fusion proteins, respectively. BCR/ABL is the oncogenic driver of Chronic Myeloid Leukemia (CML) and 30% of adult Acute Lymphatic Leukemia (ALL). Activated BCR/ABL kinase is responsible for aberrant activation of multiple signaling pathways, such as JAK/STAT, PI3K/AKT and RAS/MAPK which eventually result in leukemic transformation. Successful targeting of BCR/ABL by selective tyrosine kinase inhibitors (TKIs) such as Imatinib, Nilotinib, Dasatinib and Ponatinib are used for the treatment of Philadelphia chromosome-positive (Ph+) leukemias. Most patients with CML in the early stage (CML-CP) treated with TKIs have increased overall survival. However, TKIs have not been as effective in patients with CML blast crisis (CML-BC) or Ph+ ALL. Point mutations in the tyrosine kinase domain (TKD) of BCR/ABL have emerged as the predominant cause of acquired resistance. These mutations are observed in up to 80% of patients with CML-BC and Ph+ ALL and in ~ 50% of Imatinib-resistant patients. In the remaining 20-50% of patients the mechanism of resistance to TKIs remains elusive. The aim of this study was to investigate the mechanism of non-mutational resistance in Ph+ ALL. Methods: As models for non-mutational resistance, we used patient derived long term cultures (PDLTCs) from Ph+ ALL patients with different levels of non-mutational drug resistance and the SupB15RT, a Ph+ ALL cell-line rendered resistant by exposure to increasing doses of Imatinib and cross-resistant against all approved ABL Kinase Inhibitors (AKIs). Cell proliferation was assessed by XTT/MTT and trypan blue dye exclusion. Signaling pathway proteins were assessed by Western Blot analysis. Chromosomal karyotyping was undertaken on single cell genomes using multi-color FISH (M-FISH) technology. Mutation analysis on the ABL kinase domain was done by sequencing the heminested PCR products obtained from SupB15-WT and SupB15RT cell-lines. Results: A non-mutational resistance cell line SupB15RT, was developed by exposing SupB15 cells to an increasing concentration of Imatinib over a 3 month period. SupB15RT were able to grow in 10 µM Imatinib. SupB15RT cells were karyotypically and mutationaly identical to SupB15 WT. All approved AKIs and allosteric inhibitors like GNF-2, ABL001 and Crizotinib were unable to inhibit growth of these cells, except for Dasatinib (IC50 40nM), a multi-target kinase inhibitor. Experiments to determine the mode of resistance revealed high level (3 fold) of activation of AKT/mTOR enabling these cells to grow and proliferate. We targeted the AKT/mTOR pathway using BKM-120 (PI3 Kinase inhibitor), BEZ-235 (PI3 Kinase and mTOR pathway) and Trorin1/Torin2 (mTORC1 and mTORC2) and found that Torin-1 and Torin-2 significantly inhibited proliferation of SupB15RT, in a dose dependent manner, with an IC50 of 11-20 nM. As Dasatinib alone inhibited growth of SupB15RT cells at 40-50nm concentrations, we combined Dasatinib with Torin1 and found that the combination of these two compounds had an additive inhibitory effect on cell growth. Following this we examined clinical samples from patients. We used three different Ph+ PDLTCs: a. HP (BCR/ABL negative), b. PH (BCR/ABL positive and responsive to TKIs) and c. BV (BCR/ABL positive and non-mutational resistant to TKIs). Interestingly, we found that AKT/mTOR pathway was activated in BV cells and its proliferation was inhibited by Torin1 with IC-50 of 50nM. Conclusion: Our experiments revealed an additional pathway involved in the evolution of non-mutational resistance in Ph+ ALL which could assist in developing novel targeted therapy for Ph+ ALL patient(s) with non-mutational resistance. Disclosures Ottmann: Celgene: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Novartis: Honoraria; Takeda: Honoraria; Fusion Pharma: Honoraria; Pfizer: Honoraria; Roche: Honoraria.

8p11 Myeloproliferative syndrome with t(8;22)(p11;q11): A case report.

The 8p11 myeloproliferative syndrome (EMS), a rare myeloproliferative disease, generally progresses rapidly and is characterized by chromosomal translocations of the fibroblast growth factor receptor 1 (FGFR1) gene. The FGFR1 gene is located at chromosome 8p11 and may fuse with distinct partner genes. The breakpoint cluster region gene located at chromosome 22 is one of these partner genes. The patients' clinical phenotype is primarily dependant on the partner gene that translocates with FGFR1. Of all the available examinations, determination of the chromosome karyotype is most essential for the diagnosis of EMS. In addition, regarding treatment, allogeneic hematopoietic stem cell transplantation is currently the optimal method. The present study presented a case of 8p11 myeloproliferative syndrome with t(8;22)(p11;q11). This represents a total of 8 and 11 chromosomal translocations, which form a BCR/FGFR1 fusion gene in the patient to produce the abnormal karyotype: 46,XY,t(8;22)(p11;q11). The difference between the current case and other EMS incidences is that the patient progressed slowly and the clinical manifestation was similar to chronic myeloid leukemia (CML).

Chronic myeloid leukemia: 2018 update on diagnosis, therapy and monitoring.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100 000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults. CML is characterized by a balanced genetic translocation, t(9;22)(q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR-ABL1 fusion oncogene, which in turn translates into a BCR-ABL1 oncoprotein. Frontline therapy: Four tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, dasatinib, and bosutinib are approved by the United States Food and Drug Administration for first-line treatment of patients with newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses; this has not translated into improved long-term survival, because of the availability of effective salvage therapies. Salvage therapy: For patients who fail frontline therapy, second-line options include second and third generation TKIs. Second and third generation TKIs, although potent and selective, exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR-ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP who have failed at least 2 TKIs, and for all patients in CML advanced phases.

Gene Editing Effects of CRISPR/Cas on Breakpoint Cluster Region Gene Targets Using White-to-Blue Colony Formation Assay

Leukemia with Philadelphia chromosome positive is the most severe type in children with an extremely short average survival period. The lack of effective drugs to this type of leukemia prompted the development of alternative therapies including gene therapy. Breakpoint cluster region (BCR) chimeras are the major cancer driving mutations. In the present study, several targets of the BCR were tested for their susceptibilities to be edited by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) protein 9 system (CRISPR/Cas9). With a newly developed white-to-blue colony formation assay, the highly variable gene editing effects of CRISPR/Cas on BCR gene targets had been observed. The targets with relatively higher target effects may have clinical impact in gene therapy. This study also demonstrated the usefulness of the simple and very efficient screening assay in future gene therapy studies and clinical practice.

Current paradigms in the management of Philadelphia chromosome positive acute lymphoblastic leukemia in adults.

Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) is a biologically, clinically, and genetically distinct subtype of precursor-B ALL. The Ph chromosome, results from a reciprocal translocation of the ABL1 kinase gene on chromosome 9 to the breakpoint cluster region (BCR) gene on chromosome 22. Depending on the translocation breakpoint, typically a p210 BCR-ABL1 or a p190 BCR-ABL onc protein are generated; both are constitutively active tyrosine kinases that play a central role to alter signaling pathways of cell proliferation, survival, and self-renewal, leading to leukemogenesis. In Ph-positive ALL, the p190-BCR-ABL (minor [m]-bcr) subtype is more frequent than the p210-BCR-ABL (major [M]-bcr) subtype, commonly found in chronic myeloid leukemia. The Philadelphia chromosome is the most frequent recurrent cytogenetic abnormality in elderly patients with ALL. Its incidence increases with age, reaching ∼50% in patients with ALL aged 60 years and over. Patients traditionally had a very poor outcome with chemotherapy, particularly if they do not undergo allogeneic hematopoietic cell transplantation (allo-HCT) in first complete remission (CR1). With the availability of multiple tyrosine kinase inhibitors (TKI), the therapeutic armamentarium is expanding quickly. However, there is no consensus on how to best treat Ph-positive ALL. With modern therapy, improved outcomes have led to the emergence of a number of controversies, including the need for intensive chemotherapy, the ideal TKI, and whether all eligible patients should receive an allo-HSCT, and if so, what type. Here, we discuss these controversies in light of the available literature.

Significance of bcr-abl molecular detection in chronic myeloid leukemia patients

Important advances in the understanding of the molecular basis of chronic myeloid leukemia have resulted in the development of new therapies and changed the paradigm for managing this myeloproliferative disease. The reciprocal translocation of the abl (Abelson murine leukemia) proto-oncogene on chromosome 9 to the bcr (breakpoint cluster region) gene on chromosome 22 creates a transcriptionally active, chimeric bcr-abl gene and gives rise to the Philadelphia chromosome. 1
 The genetic hallmark of chronic myeloid leukemia (CML) is the Philadelphia chromosome (Ph), which occurs in at least 95% of CML cases as well as some cases of acute lymphocytic leukemia (ALL; approximately 5% for children, 20% for adults). It also has been reported in some other hematologic disorders, albeit rarely. 2-4 JMS 2016; 19(2):95-96

Dasatinib Inhibits Actin Fiber Reorganization and Promotes Endothelial Cell Permeability through RhoA-Rock Pathway

BackgroundThe balanced translocation of 5′ segment of the breakpoint cluster region (BCR) gene on chromosome 22 to 3′ segment of the Abelson leukemia virus (ABL) gene on chromosome 9 in chronic myeloid leukemia (CML), results in the formation of the BCR-ABL hybrid fusion gene, which has constitutively upregulated tyrosine kinase activity. Imatinib mesylate, a small molecule developed specifically to inhibit BCR-ABL kinase activity, has revolutionized the treatment of CML. Despite the overwhelming success, about 20% of patients develop resistance to imatinib due to point mutations in the BCR-ABL kinase domain. Dasatinib is one of the second generation tyrosine kinase inhibitors (TKI) that was developed to overcome the resistance to imatinib. However, dasatinib inhibits, in addition to BCR-ABL kinase, other tyrosine kinases such as Src family kinases (SFKs), leading to its unique side effects. Clinically, one of the most common non-hematologic side effects of dasatinib is peripheral edema, pleural effusion and pulmonary hypertension and it is seen 20% of patients treated with dasatinib. We investigated the effect of dasatinib on the barrier function of human microvascular endothelial cells in vitro and in vivo.MethodsIn vitro endothelial permeability assays were performed with endothelial cells grown on transwell polycarbonate membranes inserts. FITC-Dextran was added to the upper chamber followed by dasatinib (0-100 ng/ml) or vehicle (DMSO) and at various time intervals, the medium in the lower chamber was collected and the fluorescence intensity was measured. In some experiments, the monolayers were incubated with ROCK1 inhibitor y27632 for 10 minutes before the addition of dasatinib. RhoA activity assay was performed and quantified using the RhoA activation assay kit. Spreading of control and dasatinib treated endothelial cells were quantified by Image J software. Actin cytoskeleton was visualized by Immunocytochemistry. Phosphorylation of cytoskeletal proteins were assessed by Western blot with phospho specific antibodies. In vivo endothelial permeability was measured by quantifying the extravasation of intravenously administered Evans Blue to lung parenchyma in mice.ResultsThe permeability of human microvascular endothelial cells (HMEC1) to FITC-dextran increases in Transwell chambers within 5 minutes following the addition of therapeutic concentrations of dasatinib. These changes in permeability are associated with increased activation of RhoA GTPase and its effector Rho associated coiled-coil kinase I (ROCKI). RhoA inhibitor C3 almost completely inhibits dasatinib-induced increase in permeability. Under similar conditions, imatinib had no effect on permeability and it does not activate RhoA. Since integrin-induced cell spreading suppresses RhoA activation, we examined the effect of dasatinib on cell spreading on fibronectin substrate. Dasatinib impairs endothelial cell spreading in a concentration-dependent manner and induces disorganization of actin fibers. Tyrosine kinases play an essential role in transmitting signals from integrins to RhoA and we examined tyrosine phosphorylation of several cytoskeletal proteins. Dasatinib markedly inhibits tyrosine phosphorylation of p130 Crk associated substrate (p130cas), paxillin and vinculin. These results suggest inhibition of tyrosine phosphorylation of the focal adhesion plaque components by dasatinib may alter the assembly of actin fibers resulting in the activation of RhoA/ROCK pathway. In vitro, consistent with these findings, dasatinib-induced increase in the permeability is blocked by ROCK inhibitor y-23632. In vivo administration of y-27632 significantly inhibits the dasatinib-induced extravasation of Evans Blue to lung parenchyma in mice. Furthermore, dasatinib-induced microvascular permeability is attenuated in ROCK1-deficient mice.ConclusionsOur findings suggest that dasatinib inhibits actin fiber reorganization and promotes endothelial permeability through RhoA-ROCK pathway and ROCK inhibitors could serve as a therapeutic modality to ameliorate the dasatinib-induced pulmonary changes. DisclosuresNo relevant conflicts of interest to declare.