Isabel Giere

Spontaneous Breakage and Fragile Site Expression in Chronic Lymphocytic Leukemia

It has been suggested that genetic predisposition to cancer might be related to spontaneous chromosome instability or to fragile site expression. Therefore, spontaneous breakage and fragile sites were analyzed in nine untreated chronic lymphocytic leukemia (CLL) patients to determine their relation to cancer rearrangements. Five cases presented spontaneous gaps and breaks with a random distribution of breakpoints. In cultures treated with fluorodeoxyuridine or aphidicolin, 29 specific bands could be defined as fragile sites. A significant clustering of these sites was found with known common fragile sites (c-fra) and cancer breakpoints described in the literature. Most of these cancer breakpoints were involved in structural abnormalities associated with CLL (p < 0.00001). These data suggest that the expression of specific fragile sites might be related to structural chromosomal aberrations in CLL.

Structural aberrations of chromosomes 17 and 12 in chronic B-cell disorders.

Abstract: Objectives: Genomic aberrations can now be identified in approximately 80% of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) patients. In the present study, four new structural changes involving chromosomes 17 and 12 in CLL/SLL patients are described.

Complex Karyotype with PH1 Chromosome in Myelodysplasia: Cytogenetic and Molecular Studies

We report here a patient with Ph1-positive myelodysplasia with a complex karyotype. The patient presented with severe refractory anemia and ineffective erythropoiesis. In addition to t(9;22), chromosomes no. 1, 11, 12 and X also showed structural aberrations. Serial chromosome analyses revealed an increase of the Ph1-positive cell line along with the evolution of the disease (50% to 100%). Southern blot analysis showed a breakpoint cluster region (bcr) rearrangement as described for chronic myeloid leukemia (CML). The disease evolved into an acute leukemia after 4 years without any clinical evidences of CML.

Planned Pregnancy in a Chronic Myeloid Leukemia Patient in Molecular Remission

Excellent response rates and a good quality of life have been observed since the introduction of tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML) treatment. Consequently, some challenges began to appear in CML women in child-bearing age wishing to become pregnant. Currently, many women around the world are in stable major/complete molecular response MMR/CMR (MMR: <0.1% BCR-ABL/ABL and CMR: undetectable BCR-ABL mRNA by RQ-PCR transcript levels on the international scale). The condition of stable MMR/CMR is linked to a long-term virtual absence of progression to the accelerated and blastic phase and to the possibility of stopping the TKI treatment with the maintenance of a condition of CMR in a proportion of cases. Imatinib teratogenic and prescribing information prohibits the use of it during pregnancy. We describe the case of a 36-year-old female patient with CML in chronic phase who stopped imatinib after 2 years in major molecular response (MMR) to plan a pregnancy. Molecular monitoring by RQ-PCR was performed quarterly. She achieved a safe pregnancy and delivery maintaining an optimal molecular response throughout the pregnancy. Isolated literature reports have been described, but no formal advice has been described at present time.

Molecular Monitoring of Imatinib in Chronic Myeloid Leukemia Patients in Complete Cytogenetic Remission: Does Achievement of a Stable Major Molecular Response at any Time Point Identify a Privileged Group of Patients? A Multicenter Experience in Argentina and Uruguay

BACKGROUND Monitoring minimal residual disease (MRD) by real-time quantitative polymerase chain reaction (RT-PCR) in chronic myeloid leukemia (CML) patients is mandatory in the era of tyrosine kinase inhibitors. Achieving a major molecular response (MMR) at 12 and 18 months predicts a better progression and event-free survival. PATIENTS AND METHODS The objective of this prospective, multicentric study was to evaluate MRD by standardized RT-PCR in 178 patients with chronic-phase CML who were treated with imatinib at different institutions in Argentina and Uruguay and to determine if achievement of a stable MMR (BCR-ABL transcript levels < 0.1%) identifies a low-risk cytogenetic relapse group. The median age of the patients was 50 years, and 55% of them had received imatinib as first-line therapy. BCR-ABL transcript levels were measured after achievement of complete cytogenetic remission (CCyR) and at 6-month intervals. RESULTS MMR was detected in 44% patients at the start of the study. This value increased to 79% at month 36 of evaluation. Complete molecular response (CMR) also increased from 24% to 52% of patients. Not achieving a stable MMR determined a higher risk of cytogenetic relapse (9% of MMR patients not achieving an MMR vs. 1% of patients who achieved MMR). Patients with sustained MMR had a significantly better cytogenetic relapse-free survival at 48 months (97% vs. 87%; P = .008) but showed no differences in overall survival. Patients who did not remain in CCyR changed treatment. CONCLUSIONS A stable MMR is a strong predictor for a durable CCyR. Standardized molecular monitoring could replace cytogenetic analysis once CCyR is obtained. These results emphasize the validity and feasibility of molecular monitoring in all standardized medical centers of the world.

GSTM1 and GSTP1, but not GSTT1 genetic polymorphisms are associated with chronic myeloid leukemia risk and treatment response

BACKGROUND Chronic myeloid leukemia (CML) is associated to the BCR-ABL1 oncogene and can successfully be treated with tyrosine kinase inhibitors (TKIs). However, it remains still under investigation which molecular factors may influence CML risk or varying responses to TKIs. The aim of this study was to assess the role of Glutathione-S-transferases (GSTs) genetic polymorphisms in CML susceptibility and TKI clinical outcome. MATERIALS Deletion polymorphisms in GSTM1 and GSTT1 genes and the single nucleotide polymorphism in GSTP1 c.319A>G (rs1695; p.105Ile>Val) were genotyped by PCR methods in 141 CML treated patients and 141 sex- and age-matched healthy individuals. RESULTS Individual analysis of each GST gene showed no association with CML risk. A trend toward significance (p=0.07) for a recessive model was found for GSTP1 (OR: 2.04; CI: 0.94-4.4). However, the combined analysis showed that GSTM1-null/GSTP1-GG as well as GSTT1-null/GSTP1-GG were associated with CML development (p=0.03; OR: 3.54 CI: 1.2-14.57; p=0.05; OR: 12.65; CI: 1.17-21.5). The relationship with treatment outcome showed that the presence of GSTM1 gene was significantly linked with an inferior rate of major molecular response (p=0.048) and poor event free-survival (EFS) (p=0.02). Furthermore, a group of patients with GSTP1-GG genotype were significantly associated with reduced EFS comparing to those carrying other GSTP1 genotypes (p=0.049). GSTP1-GG genotypes had short time to treatment failure in a group of patients unresponsive to TKIs comparing to other GSTP1 genotypes (p=0.03). CONCLUSIONS This study highlights the significance of GSTM1 and GSTP1 polymorphisms on CML susceptibility and response to TKIs in the Argentinean population.

Molecular study of the interferon genes in chronic myeloid leukemia

The interferons alpha, beta, and w (IFNA, IFNB, IFNW), are a family of genes that have been mapped on the short arm of chromosome 9 (9p21-22). Deletions of genetic material on 9p are frequently observed in hematological diseases, particularly in lymphoid neoplasias. In this paper we have performed the molecular studies of IFNA and IFNB genes in chronic myeloid leukemia (CML) in order to determine if the deletions of these genes are prevalent in this pathology. Forty CML patients, Philadelphia positive or with BCR/ABL rearrangement, were studied at diagnosis. The analysis of IFNA and IFNB genes was performed by Southern and dot blot techniques. Homozygous or hemizygous deletions of IFNA and IFNB genes could not be detected, indicating that deletions of these genes would not be present or would be a very infrequent event in the chronic phase of the CML patients.