Novel four-way Ph translocation t(9;22;7;1)(q34;q11;q22;p13) in a chronic myeloid leukemia patient receiving tyrosine kinase inhibitor therapy

Does presence of complex translocations involving BCR::ABL1 in chronic myeloid leukemia affect the response rate to tyrosine kinase inhibitors? A systematic review of the literature

Philadelphia (Ph) chromosome (9;22)(q34;q11) comprises 90-95 % of chronic myeloid leukemia (CML), while 5-10 % of CML have translocations involving three or more chromosomes. The outcome of treating patients harbouring complex Ph-positive cytogenetics with tyrosine kinase inhibitors (TKI) is unclear. In the present systematic review, we aim to summarise the response of patients with complex Ph-positive cytogenetics to treatment with TKI therapy. We collated all available literature from databases such as PubMed, Google Scholar, Web of Science database, Cochrane library, Scopus and Embase (up until January 31st, 2024), which describe cases of patients with CML, harbouring complex Ph-positive variations (three and four-way translocations), and summarised their response to TKI therapy. The studies were screened for the following criteria: documented TKI intervention and outcome (whether CR was achieved). Studies that did not report the same, were excluded. Additionally, we report a case from our center of a 55-year-old patient with CML, positive for the Ph-chromosome, harbouring a three-way translocation involving chromosome 15 i.e. 46XX, t(9;15;22) (q34;p11;q11). Identification of BCR::ABL and involvement of chromosome 15 was carried out using conventional cytogenetics, fluorescence in situ hybridization (FISH), and quantitative PCR (qPCR). Based on the inclusion criteria, a total of 15 studies were included from which a total of 87 cases were covered. Overall, we identified 38 unique complex three- and four-way translocations across 87 Ph-positive cases and found that 85 patients with complex Ph-positive cytogenetics achieved complete remission upon treatment and did not appear to have a lesser response to TKI therapy.

The spectrum of chromosomal translocations in the Arab world: ethnic-specific chromosomal translocations and their relevance to diseases

Chromosomal translocations (CTs) are the most common type of structural chromosomal abnormalities in humans. CTs have been reported in several studies in the Arab world, but the frequency and spectrum of these translocations are not well characterized. The aim of this study is to conduct a systematic review to estimate the frequency and spectrum of CTs in the 22 Arab countries. Four literature databases were searched: PubMed, Science Direct, Scopus, and Web of Science, from the time of inception until July 2021. A combination of broad search terms was used to collect all possible CTs reported in the Arab world. In addition to the literature databases, all captured CTs were searched in three chromosomal rearrangement databases (Mitelman Database, CytoD 1.0 Database, and the Atlas of Genetics and Cytogenetics in Oncology and Hematology), along with PubMed and Google Scholar, to check whether the CTs are unique to the Arabs or shared between Arabs and non-Arabs. A total of 9,053 titles and abstracts were screened, of which 168 studies met our inclusion criteria, and 378 CTs were identified in 15 Arab countries, of which 57 CTs were unique to Arab patients. Approximately 89% of the identified CTs involved autosomal chromosomes. Three CTs, t(9;22), t(13;14), and t(14;18), showed the highest frequency, which were associated with hematological malignancies, recurrent pregnancy loss, and follicular lymphoma, respectively. Complex CTs were commonly reported among Arabs, with a total of 44 CTs, of which 12 were unique to Arabs. This is the first study to focus on the spectrum of CTs in the Arab world and compressively map the ethnic-specific CTs relevant to cancer. It seems that there is a distinctive genotype of Arabs with CTs, of which some manifested with unique clinical phenotypes. Although ethnic-specific CTs are highly relevant to disease mechanism, they are understudied and need to be thoroughly addressed.

Overview of clinical and genetic features of CML patients with variant Philadelphia translocations involving chromosome 7: A case series

Variant Philadelphia (Ph) translocations involving chromosome 7 are rarely seen in Chronic Myeloid Leukemia (CML) patients. It is aimed to contribute new cases to the literature by reviewing the cases in our archive and shed light into the understanding of the role of chromosome 7 in CML. This study was carried out in 237 newly diagnosed CML patients with variant Ph translocations. Among the patients, those with variant Ph translocation involving chromosome 7 were evaluated in terms of clinical and genetic characteristics. Chromosome analysis was performed on 24 and 48 h of bone marrow cultures. FISH analysis was performed with BCR-ABL1 dual color dual fusion translocation probes. BCR-ABL1 transcript levels were analysed by QRT-PCR and results were reported as BCR-ABL1/ABL1 (BCR-ABL1 (IS) %) according to international scale. Four of the patients had variant Ph translocations including chromosome 7. The karyotypes were 46,XX,t(7;9;22)(p13;q34;q11); 46,XX,t(7;9;22)(p21;q34;q11); 46,XX,t(7;9;22)(q22;q34;q11) and 46,XY,t(7;9;22)(q22;q34;q11). The breakpoints demonstrated by cytogenetic analysis were confirmed by FISH analysis. Monitoring by QRT-PCR showed that patients with variant Ph translocation including 7p13 and 7p21 had a dramatic decrease in BCR-ABL1 levels resulting in complete hematological, complete cytogenetic and deep molecular responses. Despite achieving complete hematological, complete cytogenetic response in two patients with variant Philadelphia translocation, including 7q22, no major molecular response was achieved and both patients are still in the warning category. Response to tyrosine kinase inhibitör therapy may be associated with both the variant translocation mechanism and new gene interactions that occur due to the breakpoints of additional chromosomes involved in translocation.

Molecular techniques for the personalised management of patients with chronic myeloid leukaemia

Chronic myeloid leukemia (CML) is the paradigm for targeted cancer therapy. RT-qPCR is the gold standard for monitoring response to tyrosine kinase-inhibitor (TKI) therapy based on the reduction of blood or bone marrow BCR-ABL1. Some patients with CML and very low or undetectable levels of BCR-ABL1 transcripts can stop TKI-therapy without CML recurrence. However, about 60 percent of patients discontinuing TKI-therapy have rapid leukaemia recurrence. This has increased the need for more sensitive and specific techniques to measure residual CML cells. The clinical challenge is to determine when it is safe to stop TKI-therapy. In this review we describe and critically evaluate the current state of CML clinical management, different technologies used to monitor measurable residual disease (MRD) focus on comparingRT-qPCR and new methods entering clinical practice. We discuss advantages and disadvantages of new methods.

A Novel Four-Way Complex Variant Translocation Involving Chromosome 46,XY,t(4;9;19;22)(q25:q34;p13.3;q11.2) in a Chronic Myeloid Leukemia Patient

Philadelphia (Ph) chromosome (9;22)(q34;q11) is well established in more than 90% of chronic myeloid leukemia (CML) patients, and the remaining 5-8% of CML patients show variant and complex translocations, with the involvement of third, fourth, or fifth chromosome other than 9;22. However, in very rare cases, the fourth chromosome is involved. Here, we found a novel case of four-way Ph+ chromosome translocation involving 46,XY,t(4;9;19;22)(q25:q34;p13.3;q11.2) with CML in the chronic phase. Complete blood cell count of the CML patient was carried out to obtain total leukocytes count, hemoglobin, and platelets. Fluorescence in situ hybridization technique was used for the identification of BCR-ABL fusion gene, and cytogenetic test for the confirmation of Ph (9;22)(q34;q11) and the mechanism of variant translocation in the bone marrow. The patient is successfully treated with a dose of 400 mg/day imatinib mesylate (Gleevec). We observed a significant decrease in white blood cell count of 11.7 × 10(9)/L after 48-month follow-up. Patient started feeling better generally. There was a reduction in the swelling of the body, fatigue, and anxiety.

A novel cytogenetic abnormality t(7;8)(p11.2:q11.2) and a four-way Philadelphia translocation in an imatinib mesylate-resistant chronic myeloid leukemia patient

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) chromosome, created by a reciprocal translocation t(9:22)(q34;q11) which forms the chimeric gene, BCR-ABL. Variant Ph chromosome translocations involving chromosomes other than 9 and 22 have been identified in 5–10% of CML cases. Four-way Ph chromosome translocations are an extremely rare event in myeloid malignancies and the phenotypic consequences of such rearrangements have not been investigated. Deletions in chromosome 9 are known to be associated with a poor prognosis. In the present study, a novel case of Ph chromosome-positive CML in blast crisis is reported. A four-way Ph translocation was identified, involving five chromosomal regions, 9p21, 9q34, 12p13.3, 20q11.2 and 22q11.2, as well as an unbalanced translocation, der(7)t(7;8)(p11.2;q11.2). Since the majority of CML cases are currently treated with imatinib, variant rearrangements in general have no specific prognostic significance, although the mechanisms involved in resistance to therapy have yet to be investigated. In the present case, multiple partial deletions, including ABL and ASS genes on chromosome 9, the region 7p11.2 to 7pter, 8q11.2 to 8pter and two regions on chromosome 12, were identified. An additional Ph chromosome was also detected. Immunophenotyping indicated that the patient had biphenotypic leukemia. The patient did not respond positively to imatinib chemotherapy and died for unknown reasons, one month after diagnosis. The underlying mechanisms and prognostic implications of these cytogenetic abnormalities are discussed.