Current practices in the management of chronic myeloid leukemia

Prenatal diagnosis of sex chromosomal inversion, translocation and deletion

The aim of the present study was to perform comprehensive prenatal diagnosis using various detection techniques on a fetus in a high‑risk pregnant woman, and to provide genetic counseling for the patient and her family so as to avoid birth defects. The routine karyotype analysis via amniocentesis, fluorescence in situ hybridization, and whole genome microarray technique were performed for the prenatal diagnosis of the fetus. The fetal karyotype was 46,X,ish der(X) inv(X)(p22.3q28)t(X;Y)(q28;q11.2)(XYqter+,SRY‑,DXZ1+, RP11‑64L19+,STS+,XYpter+); namely, one fetal X chromosome belonged to the derivative imbalanced chromosome and this chromosome demonstrated complex chromosomal rearrangements involving inversion, translocation and deletion. Notably, pericentric inversion between Xp22.3 and Xq28 was identified, and the chromosomal microarray technique confirmed that the long arm q28 of the derivative X chromosome had a 1.241‑Mb deletion in Xq28, which included Online Mendelian Inheritance in Man genes such as coagulation factor VIII, glucose‑6‑phosphate dehydrogenase, inhibitor of nuclear factor‑κB kinase subunit γ, trimethyllysine hydroxylase ε, Ras‑related protein Rab‑39B and chloride intracellular channel 2. In addition, this chromosome also exhibited the local translocation of fragment Yq11.21‑q11.23, which did not include the sex determining region Y gene. This fetus demonstrated deletion, inversion and translocation syndrome, and may exhibit the corresponding clinical phenotypes (e.g., intellectual disability or general delayed development) (1) of such chromosome abnormalities after birth. Therefore, in prenatal diagnosis, a variety of genetic diagnostic techniques should be comprehensively used based on specific clinical situations, which may accurately reveal the nature, sources and manifestations of the derivative chromosome abnormalities and avoid the birth of children with defects.

Chronic myeloid leukemia patients in Tunisia: epidemiology and outcome in the imatinib era (a multicentric experience)

Data are limited in developing countries regarding the clinicopathologic features and response to therapy of chronic myeloid leukemia (CML) in the era of imatinib (IM). The objective of this study is to report on the clinicoepidemiologic features of CML in Tunisia, to evaluate the long-term outcome of patients in chronic (CP) or accelerated phase (AP) treated with IM 400 mg daily as frontline therapy, and to determine imatinib's efficacy and safety. From October 2002 to December 2014, 410 CML patients were treated with IM in six Tunisian departments of hematology. Response (hematologic, cytogenetic, and molecular responses) and outcome-overall survival (OS), event-free survival (EFS), and progression-free survival (PFS)-were evaluated. The following prognostic factors were analyzed for their impact on the European leukemia net (ELN) response, OS, EFS, and PFS at 5 years: age, sex, leukocyte count, Sokal score, European Treatment and Outcome Study (EUTOS) score, CML phase, time to starting IM, and impact of adverse events. The median age was 45 years (3-85 years). Two hundred ten (51.2%) patients were male. Splenomegaly was present in 322 of the 410 (79%). Additional cytogenetic abnormalities were encountered in 25 (6.3%) patients. At diagnosis, 379 (92.4%) patients were in CP, 31 (7.6%) were in AP. The Sokal risk was low in 87 (22.5%), intermediate in 138 (35.7%), and high in 164 patients (41.9%). The EUTOS risk was low in 217 (74%), and high in 77 (26%) patients. The rates of cumulative complete cytogenetic response (CCyR), major molecular response (MMR), and molecular response 4/5 log (MR4.5) in CP/AP-CML patients were 72, 68.4, and 46.4%, respectively. The median time to reach CCyR, MMR, and MR4.5 was 6 months (3-51), 18 months (3-72), and 24 months (3-100), respectively. According to the ELN criteria, optimal, suboptimal response, and failure were noted in 206 (51.8%), 61 (15.3%), and 125 (31.4%) patients, respectively. Five-year event-free survival (EFS), progression-free survival (PFS), and overall survival (OS) were 81, 90, and 90%, respectively. By multivariate analysis, AP, high EUTOS risk, and baseline WBC ≥ 150G/l remained independent predictive factors of non-optimal response to IM. The adverse events (AE) of IM were moderate and tolerable. With the caveats that the monitoring of the disease was not optimal, response rates were similar to those reported in previous studies. It is clear to us that improvements should be made in treatment of AP-CML and high Sokal risk group of CP-CML. The frontline use of second-generation tyrosine kinase inhibitor (TKI) is expected to improve the results of the first-line treatment of these high-risk Tunisian patients, but cost and accessibility of this therapy remain the problems in developing countries.

Integration of microarray analysis into the clinical diagnosis of hematological malignancies: How much can we improve cytogenetic testing?

Purpose

To evaluate the clinical utility, diagnostic yield and rationale of integrating microarray analysis in the clinical diagnosis of hematological malignancies in comparison with classical chromosome karyotyping/fluorescence in situ hybridization (FISH).

Methods

G-banded chromosome analysis, FISH and microarray studies using customized CGH and CGH+SNP designs were performed on 27 samples from patients with hematological malignancies. A comprehensive comparison of the results obtained by three methods was conducted to evaluate benefits and limitations of these techniques for clinical diagnosis.

Results

Overall, 89.7% of chromosomal abnormalities identified by karyotyping/FISH studies were also detectable by microarray. Among 183 acquired copy number alterations (CNAs) identified by microarray, 94 were additional findings revealed in 14 cases (52%), and at least 30% of CNAs were in genomic regions of diagnostic/prognostic significance. Approximately 30% of novel alterations detected by microarray were >20 Mb in size. Balanced abnormalities were not detected by microarray; however, of the 19 apparently “balanced” rearrangements, 55% (6/11) of recurrent and 13% (1/8) of non-recurrent translocations had alterations at the breakpoints discovered by microarray.

Conclusion

Microarray technology enables accurate, cost-effective and time-efficient whole-genome analysis at a resolution significantly higher than that of conventional karyotyping and FISH. Array-CGH showed advantage in identification of cryptic imbalances and detection of clonal aberrations in population of non-dividing cancer cells and samples with poor chromosome morphology. The integration of microarray analysis into the cytogenetic diagnosis of hematologic malignancies has the potential to improve patient management by providing clinicians with additional disease specific and potentially clinically actionable genomic alterations.

Practical management of patients with chronic myeloid leukemia who develop tyrosine kinase inhibitor-resistant BCR-ABL1 mutations

Five BCR-ABL1 tyrosine kinase inhibitors (TKIs), imatinib, nilotinib, dasatinib, bosutinib, and ponatinib, are currently approved for the treatment of chronic myeloid leukemia (CML). Standard treatment of CML with TKIs is highly effective in reducing disease burden, delaying disease progression, and prolonging overall survival of patients; however, resistance to TKI treatment has become an increasingly important cause of treatment failure. The emergence of mutations in the BCR-ABL1 kinase domain is a common mechanism of TKI resistance, and laboratory testing to detect these mutations is currently available for clinical use. Patients who do not respond or have lost their response to TKI therapy should be considered for mutational testing. Despite clinical practice guidelines that recommend testing for BCR-ABL1 mutations in patients with clinical signs of TKI resistance, many oncologists and hematologists managing patients with CML do not perform such testing. This review addresses outstanding questions related to when testing should be conducted, what type of testing should be done, and how testing results should be applied to subsequent therapeutic decisions. It describes how BCR-ABL1 kinase domain mutations confer resistance, outlines the prevalence of mutations in patients with resistance to TKIs, summarizes the common and investigational methods used in mutational testing, and presents an algorithm reflecting a clinical perspective on how and when to conduct mutational testing, and what to do with test results.