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.

Are Estrogen Receptor Genomic Aberrations Predictive of Hormone Therapy Response in Breast Cancer?

CONTEXT: Breast cancer is the most common cancer in women worldwide. Estrogen receptor (ER) positive breast cancer constitutes the majority of these cancers. Hormone therapy has significantly improved clinical outcomes for early- and late-stage hormone receptor positive breast cancer. Although most patients with early stage breast cancer are treated with curative intent, approximately 20% - 30% of patients eventually experience a recurrence. During the last two decades, there have been tremendous efforts to understand the biological mechanisms of hormone therapy resistance, with the ultimate goal of implementing new therapeutic strategies to improve the current treatments for ER positive breast cancer. Several mechanisms of hormone therapy resistance have been proposed, including genetic alterations that lead to altered ER expression or ERs with changed protein sequence. EVIDENCE ACQUISITION: A Pubmed search was performed utilizing various related terms. Articles over the past 20 years were analyzed and selected for review. RESULTS: On the basis of published studies, the frequencies of ESR1 (the gene encoding ER) mutations in ER positive metastatic breast cancer range from 11% to 55%. Future larger prospective studies with standardized mutation detection methods may be necessary to determine the true incidence of ESR1 mutations. ESR1 amplification in breast cancer remains a controversial issue, with numerous studies either confirmed or challenged the reports of ESR1 amplification. The combination of intra-tumor heterogeneity regarding ESR1 copy number alterations and low level ESR1 copy number increase may account for these discrepancies. CONCLUSIONS: While numerous unknown issues on the role of ESR1 mutations in advanced breast cancer remain, these new findings will certainly deepen current knowledge on molecular evolution of breast cancer and acquired resistance to hormone therapy.

Detection of Gene Amplification by Multiplex Ligation-Dependent Probe Amplification in Comparison with In Situ Hybridization and Immunohistochemistry.

Gene amplification is an important mechanism in the development and progression of cancer. Currently, gene amplification status is generally determined by in situ hybridization (ISH). Multiplex ligation-dependent probe amplification (MLPA) is a PCR-based method that allows copy number detection of up to 50 nucleic acid sequences in one reaction. The aim of the present study was to compare results for HER2, CCND1, MYC and ESR1 gene amplification detected by MLPA with fluorescent in situ hybridization (FISH) and chromogenic in situ hybridization (CISH) as clinically approved methods. Tissue samples of 170 invasive breast cancers were collected. All were ER positive. Tissue samples had previously been tested for HER2 using immunohistochemistry. Amplification of the selected genes were assessed using MLPA, FISH and CISH and results were compared. HER2 MLPA and ISH results were also compared with HER2 immunohistochemistry (IHC) which detects protein overexpression. Amplification of HER2, CCND1, MYC and ESR1 by MLPA were found in 9%, 19%, 20% and 2% of samples, respectively. Amplification of HER2, CCND1, MYC and ESR1 by FISH was noted in 7%, 16%, 16% and 1% of samples, respectively. A high level of concordance was found between MLPA/ FISH (HER2: 88%, CCND1: 88%, MYC: 86%, ESR1: 92%) and MLPA/ CISH (HER2: 84%). Of all IHC 3+ cases, 91% were amplified by MLPA. In IHC 2+ group, 31% were MLPA amplified. In IHC 1+ group, 2% were MLPA amplified. None of the IHC 0 cases were amplified by MLPA. Our results indicate that there is a good correlation between MLPA, IHC and ISH results. Therefore, MLPA can serve as an alternative to ISH for detection of gene amplification.

Expression profiling of breast cancer patients treated with tamoxifen: prognostic or predictive significance.

Approximately 70% of breast cancers are estrogen receptor (ER) positive, and interfering with estrogen action with tamoxifen has been the treatment of choice for ER-positive breast cancer patients. However, about a third of patients treated with tamoxifen will experience a recurrence of cancer. The expression analysis of selected genes involved in tamoxifen/estrogen and receptor tyrosine kinase signaling pathways can help to further decipher mechanisms of recurrence in ER+ tumors and contribute to the development of prognostic and possibly predictive biomarkers. We selected seven genes (ESR1, CCND1, MYC, HER2, AKT1, AIB1 and NCOR1), which are components of these pathways. A case-control study was designed. All patients in the control group had received standard adjuvant tamoxifen treatment for 5 years without any evidence of recurrence. Patients in the case group had experienced an early recurrence of cancer while receiving tamoxifen treatment. Expression levels of selected genes in both groups were compared. Expression levels of CCND1 (p < 0.001), HER2 (p < 0.001), AKT1 (p = 0.038) and AIB1 (p = 0.004) were significantly higher in recurrent tumors compared to non-recurrent tumors, while expression levels of NCOR1 (p < 0.001) were significantly lower in recurrent tumors. In multivariable analysis, CCND1 (p < 0.001), HER2 (p = 0.003), AIB1 (p = 0.036) and NCOR1 (p = 0.002) remained significant predictors of recurrence. Expression levels of CCND1, HER2, AIB1 and NCOR1 were detected as independent predictors of recurrence in this cohort of tamoxifen-treated patients. Further work should be done to validate the predictive value of this gene profile for tamoxifen response.

Cancer-testis genes as candidates for immunotherapy in breast cancer.

Cancer-testis (CT) antigens are tumor-associated antigens attracting immunologists for their possible application in the immunotherapy of cancer. Several clinical trials have assessed their therapeutic potentials in cancer patients. Breast cancers, especially triple-negative cancers are among those with significant expression of CT genes. Identification of CT genes with high expression in cancer patients is the prerequisite for any immunotherapeutic approach. CT genes have gained attention not only for immunotherapy of cancer patients, but also for immunoprevention in high-risk individuals. Many CT genes have proved to be immunogenic in breast cancer patients suggesting the basis for the development of polyvalent vaccines.

Prognostic and predictive value of copy number alterations in invasive breast cancer as determined by multiplex ligation-dependent probe amplification.

BACKGROUND: Breast cancer is a leading cause of morbidity and mortality in women worldwide. About 70 % of breast cancers are estrogen receptor (ER) positive. Blocking estrogen action by tamoxifen has been the treatment of choice in ER positive breast cancers for more than 30 years. In the past, several studies have revealed associations between gene copy number alterations and responsiveness to tamoxifen therapy, but so far no single gene copy number alteration could completely explain the response variation observed between individual breast cancer patients. Here, we set out to perform a simultaneous analysis of copy number alterations of several genes involved in the prognosis and response to therapy by multiplex ligation-dependent probe amplification (MLPA). METHODS: A case-control study was designed encompassing 170 non-metastatic ER positive breast cancer patients (case group = 85, control group = 85). All patients in the control group had received standard adjuvant tamoxifen treatment for 5 years without any evidence of recurrence. Patients in the case group had experienced early recurrences while receiving tamoxifen treatment. 76 % of the patients of the case group and 73 % of the patients of the control group had received anthracycline-based adjuvant chemotherapy. Gene copy number alterations detected by MLPA in both groups were compared. RESULTS: Amplification of CCND1 (OR = 3.13; 95 % CI = 1.35 to 7.26; p = 0.006) and TOP2A (OR = 3.05; 95 % CI = 1.13 to 8.24; p = 0.022) were significantly more prevalent in the case group, compared to the control group. In a multivariate analysis CCND1 (p = 0.01) and TOP2A (p = 0.041) amplifications remained significant predictors of recurrence. CONCLUSIONS: Our results indicate that CCND1 amplification may serve as a useful biomarker for hormone responsiveness, and that TOP2A amplification may serve as a useful prognostic biomarker.

Cancer stem cells and response to therapy.

The cancer stem cell (CSC) model states that cancers are organized in cellular hierarchies, which explains the functional heterogeneity often seen in tumors. Like normal tissue stem cells, CSCs are capable of self-renewal, either by symmetric or asymmetric cell division, and have the exclusive ability to reproduce malignant tumors indefinitely. Current systemic cancer therapies frequently fail to eliminate advanced tumors, which may be due to their inability to effectively target CSC populations. It has been shown that embryonic pathways such as Wnt, Hedgehog, and Notch control self-renewal and cell fate decisions of stem cells and progenitor cells. These are evolutionary conserved pathways, involved in CSC maintenance. Targeting these p.

Evaluation of PKM2 and MAPK8IP2 Polymorphism in Ameloblastic Carcinoma: A Retrospective Quantitative Study.

Ameloblastic carcinoma (AC) is a rare malignant epithelial odontogenic tumor that histologically retains the features of ameloblastic differentiation and exhibits cytological features of malignancy in the primary or recurrent tumor. It may develop within a preexisting ameloblastoma or arise de novo or from an odontogenic cyst. Epidemiological evidence shows that human cancer is generally caused by genotoxic factors, genes involved in the susceptibility of cancer, including those involved in metabolism or detoxification of genotoxic environment and those controlling DNA replication. Nowadays, gene polymorphism has an important role in development of malignant tumor. We report a case series study of ameloblastic carcinoma and ameloblastoma to show the role of PKM2 and MAPK8IP2 polymorphisms in these tumors. The DNA was extracted separately from specimens in paraffin sections of the tumor. Polymorphism of these genes was determined by PCR-RFLP (Polymerase Chain Reaction-Restriction fragment length polymorphism) method. The allele distributions of all samples were in Hardy-Weinberg equilibrium. The genotype and allele distribution in these genes were not statistically different between patients and controls.