Marta Pestrin

HEX expression and localization in normal mammary gland and breast carcinoma

BackgroundThe homeobox gene HEX is expressed in several cell types during different phases of animal development. It encodes for a protein localized in both the nucleus and the cytoplasm. During early mouse development, HEX is expressed in the primitive endoderm of blastocyst. Later, HEX is expressed in developing thyroid, liver, lung, as well as in haematopoietic progenitors and endothelial cells. Absence of nuclear expression has been observed during neoplastic transformation of the thyroid follicular cells. Aim of the present study was to evaluate the localization and the function of the protein HEX in normal and tumoral breast tissues and in breast cancer cell lines.MethodsHEX expression and nuclear localization were investigated by immunohistochemistry in normal and cancerous breast tissue, as well as in breast cancer cell lines. HEX mRNA levels were evaluated by real-time PCR. Effects of HEX expression on Sodium Iodide Symporter (NIS) gene promoter activity was investigated by HeLa cell transfection.ResultsIn normal breast HEX was detected both in the nucleus and in the cytoplasm. In both ductal and lobular breast carcinomas, a great reduction of nuclear HEX was observed. In several cells from normal breast tissue as well as in MCF-7 and T47D cell line, HEX was observed in the nucleolus. MCF-7 treatment with all-trans retinoic acid enhanced HEX expression and induced a diffuse nuclear localization. Enhanced HEX expression and diffuse nuclear localization were also obtained when MCF-7 cells were treated with inhibitors of histone deacetylases such as sodium butyrate and trichostatin A. With respect to normal non-lactating breast, the amount of nuclear HEX was greatly increased in lactating tissue. Transfection experiments demonstrated that HEX is able to up-regulate the activity of NIS promoter.ConclusionOur data indicate that localization of HEX is regulated in epithelial breast cells. Since modification of localization occurs during lactation and tumorigenesis, we suggest that HEX may play a role in differentiation of the epithelial breast cell.

The efficacy of lapatinib in metastatic breast cancer with HER2 non-amplified primary tumors and EGFR positive circulating tumor cells: a proof-of-concept study.

Background Analysis of circulating tumor cells (CTCs) provides real-time measures of cancer sub-populations with potential for CTC-directed therapeutics. We examined whether lapatinib which binds both HER2 and EGFR could induce depletion of the EGFR-positive pool of CTCs, which may in turn lead to clinical benefits. Patients and Methods Patients with metastatic breast cancer and HER2 non-amplified primary tumors with EGFR-positive CTCs were recruited and lapatinib 1500 mg daily was administered, in a standard two step phase 2 trial. Results There were no responses leading to termination at the first analysis with 16 patients recruited out of 43 screened. In 6 out of 14 (43%) individuals eligible for the efficacy analysis, a decrease in CTCs was observed with most of these having a greater decrease in their EGFR-positive CTC pool. Conclusions This is one of the first studies of CTC-directed therapeutics and suggests that lapatinib monotherapy is not having any demonstrable clinical effects by reducing the EGFR-positive pool of CTCs in HER2 non-amplified primary tumors. Our attempt to expand the pool of patients eligible for a targeted therapy was unsuccessful; the role of clonal populations in cancer biology and therapeutic strategies to control them will require extensive evaluation in years to come. Trial Registration Clinical trials.gov NCT00820924

Can Biomarker Assessment on Circulating Tumor Cells Help Direct Therapy in Metastatic Breast Cancer

Circulating tumor cell (CTC) count has prognostic significance in metastatic breast cancer, but the predictive utility of CTCs is uncertain. Molecular studies on CTCs have often been limited by a low number of CTCs isolated from a high background of leukocytes. Improved enrichment techniques are now allowing molecular characterisation of single CTCs, whereby molecular markers on single CTCs may provide a real-time assessment of tumor biomarker status from a blood test or “liquid biopsy”, potentially negating the need for a more invasive tissue biopsy. The predictive ability of CTC biomarker analysis has predominantly been assessed in relation to HER2, with variable and inconclusive results. Limited data exist for other biomarkers, such as the estrogen receptor. In addition to the need to define and validate the most accurate and reproducible method for CTC molecular analysis, the clinical relevance of biomarkers, including gain of HER2 on CTC after HER2 negative primary breast cancer, remains uncertain. This review summarises the currently available data relating to biomarker evaluation on CTCs and its role in directing management in metastatic breast cancer, discusses limitations, and outlines measures that may enable future development of this approach.

Markers of the uPA system and common prognostic factors in breast cancer.

The urokinase plasminogen activator (uPA) system includes uPA and plasminogen activator inhibitor types 1 (PAI-1) and 2 that mainly act by regulating extracellular matrix degradation, and it is involved in tumor progression. The -675 4G/5G polymorphism of the PAI-1 gene regulates PAI-1 activity in serum. We aimed at studying the -675 4G/5G polymorphism of the PAI-1 gene and uPA, PAI-1, and cyclooxygenase-2 (COX-2) immunohistochemical expression in a series of breast cancer cases. Homozygosity for the 4G allele of the PAI-1 gene was associated with node-positive breast cancer ( P = .02). We showed a direct correlation between uPA and estrogen receptor expression ( P = .03); negative uPA expression was associated with negative hormonal expression, high tumor grade, and high proliferation index ( P < .05). A direct correlation was seen between uPA and PAI-1, uPA and COX-2, and PAI-1 and COX-2 expression ( P < .05). Interaction between uPA and COX-2 systems in breast cancer deserves further study.

Taxanes in the elderly: Can we gain as much and be less toxic?

Taxanes are very effective agents in several types of cancer. However, their activity is counterbalanced by side effects that could represent a limitation of their use in older cancer patients. This review aims at evaluating whether or not there are data supporting a tailored use of standard taxanes i.e. docetaxel and paclitaxel in elderly patients with the aim to increase their therapeutic index. In addition, recent data on the role of nanoparticle albumine-bound paclitaxel in breast cancer are discussed in this paper.

Role of lapatinib in the first-line treatment of patients with metastatic breast cancer

Lapatinib is a dual tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR/ErbB1) and human epidermal growth factor receptor 2 (HER2/ErbB2). EGFR and HER2 overexpression is associated with aggressive breast cancer with a high risk of disease relapse and death. Although lapatinib targets both EGFR and HER2, its effects on HER2 appear to be more critical. The role of lapatinib in the first-line setting remains unclear. A phase II first-line monotherapy lapatinib trial in HER2-therapy-naïve metastatic breast cancer (MBC) patients confirms efficacy in HER2-positive tumors. Retrospective analysis of a phase III, first-line MBC study confirmed incremental benefit from lapatinib and paclitaxel over paclitaxel alone in HER2-positive disease. A prospective phase III study confirms superiority of letrozole and lapatinib over letrozole alone in HER2-positive MBC. Further investigation is required to define the potential first-line role for lapatinib. Particular strengths appear to be its manageable toxicity profile, lack of cross resistance with trastuzumab, activity in central nervous system disease, and synergy in combination with other anticancer therapy. Current limitations are lack of dosing recommendations from early trials, lack of predictive biomarkers beyond HER2 status, and lack of large prospective phase III trials for HER2-positive disease in the first-line setting. The role of lapatinib in HER2-negative disease is unclear.

Significance of Micrometastases: Circulating Tumor Cells and Disseminated Tumor Cells in Early Breast Cancer

Adjuvant systemic therapy targets minimal residual disease. Our current clinical approach in the adjuvant setting is to presume, rather than confirm, the presence of minimal residual disease. Based on assessment of the primary tumor, we estimate an individual’s recurrence risk. Subsequent treatment decisions are based on characteristics of the primary tumor, with the presumption of consistent biology and treatment sensitivity between micrometastases and the primary lesion. An alternative approach is to identify micrometastatic disease. Detection of disseminated tumor cells (DTC) in the bone marrow and circulating tumor cells (CTC) from peripheral blood collection may offer quantification and biocharacterization of residual disease. This paper will review the prognostic and predictive potential of micrometastatic disease in early breast cancer.

Adjuvant chemotherapy--the dark side of clinical trials. Have we learnt more?

Large adjuvant trials, over many years, have randomised thousands of women with early breast cancer to different regimens. They have been instrumental in defining our current approach in the adjuvant setting. However in clinical practice with each patient, we still have the difficulty of targeting their specific therapy, as results relating to the average trial population are often not transferable to the individual. This review of adjuvant chemotherapy trials focuses on the heterogeneity of disease, treatment, mechanisms of chemotherapy action and risk. These issues are of key importance in our interpretation and application of results from adjuvant trials. A critical issue in adjuvant chemotherapy is identification of patients at high risk of recurrence who have chemosensitive tumours. Risk of relapse does not always correlate with chemosensitivity, and cytotoxic therapy in patients with chemorefractory disease may be ineffective and associated only with toxicity. Rather than general sensitivity to cytotoxics, we need predictive biomarkers to guide which specific therapy will be effective in a particular patient. Assessment of specific biomarkers as predictive tools may individualise care and see chemotherapy implementation as targeted agents, with tumour heterogeneity reflected in heterogeneity of intervention. Already with trastuzumab, we have a subgroup predicted by Her-2 gene amplification. Anthracyclines and taxanes, whilst widely used, do not yet have prospectively proven biomarkers to predict response. Potential biomarkers for anthracyclines include topoisomerase II alpha and markers of DNA repair dysfunction, whilst for taxanes, microtubule-associated proteins may play a role. The basal phenotype may be predictive of benefit from DNA damaging agents.

The continued evidence from overviews: What is the clinical utility?

The Oxford Overview process has provided us with extremely high-powered meta-analyses assessing the role of adjuvant chemotherapy in early breast cancer. From the most recent publication, the proportional benefits from chemotherapy are relatively equivalent across all patient subgroups, a finding contradictory to our growing understanding of the role of tumour biology in dictating chemosensitivity. Several factors, including heterogeneity of patient groups and chemotherapy regimens, lack of data on underlying tumour biological subtypes, and confounding effect of chemotherapy-induced ovarian suppression in premenopausal women with hormone receptor positive breast cancer, impact on the applicability and clinical utility of the Overview in current and future oncological practice. With these considerations, the Overview has become less clinically relevant as a tool for guiding adjuvant chemotherapy treatment decisions, and a new direction is required.

Adjuvant Chemotherapy: Which Patient? What Regimen?

In the past, treatment decisions regarding adjuvant chemotherapy in early breast cancer (EBC) were made solely based on clinicopathologic factors. However, with increased awareness of the importance of underlying tumor biology, we are now able to use genomic analyses to determine molecular breast cancer subtype and thus identify patients with tumors that are chemotherapy resistant and unlikely to benefit from the addition of chemotherapy. Although genomics has allowed some patients to avoid chemotherapy-specifically those with luminal A-like breast cancer-these assays do not indicate which regimen is most appropriate. For this, consideration must be given to the combination of underlying tumor biology, tumor stage, and patient characteristics, such as age and tolerability of side effects.