High-dose chemotherapy with hematopoietic stem-cell transplantation for breast cancer: current status, future trends

Treating breast cancer with cell-based approaches: an overview

INTRODUCTION

Breast cancer is the most common malignancy in women. Despite there being considerable progress in the treatment of this disease, metastatic dissemination is still considered an incurable condition at the present time, causing 500,000 deaths worldwide every year. Although most of the research efforts have been focused on pharmacological approaches, over the last three decades, the use of bone marrow and peripheral blood-derived cell therapy approaches have been attempted and developed. Areas covered: This review will briefly address cell therapy for breast cancer, including autologous stem cell transplantations for overcoming the myelosuppressive effects of high-dose chemotherapy, allogeneic stem cell transplants and adoptive immunotherapy using bone-marrow derived T-cells. Expert opinion: The treatment of breast cancer using bone marrow or peripheral-blood derived cells has evolved from a supportive care approach to allow dose escalation of conventional chemotherapy to a therapeutic strategy aimed at eliciting immune cell mediated anticancer immunity. This latter principle has led to the development of adoptive immunotherapies, either with 'natural' or genetically engineered effectors, which are being intensively investigated for their great potential against several solid tumors, including breast cancer.

Prognostic Value of EMT-Circulating Tumor Cells in Metastatic Breast Cancer Patients Undergoing High-Dose Chemotherapy with Autologous Hematopoietic Stem Cell Transplantation

BACKGROUND

Circulating tumor cells (CTCs) are an independent prognostic factor in metastatic breast cancer (MBC) patients treated by conventional dose chemotherapy. The aim of this study was to determine the role of CTCs and CTCs undergoing epithelial-mesenchymal transition (EMT) in metastatic breast cancer. We used the platform of high-dose chemotherapy (HDCT) and autologous hematopoietic stem cell transplantation (AHSCT) to study the CTCs and CTCs with EMT.

PATIENTS AND METHODS

CTCs were enumerated in 21 MBC patients before apheresis and 1 month after AHSCT. CD34-depleted apheresis products were analyzed for CD326+ epithelial and Aldefluor+ cancer stem cells (CSC) by flow cytometry and were depleted of CD45+ cells and assessed for EMT-inducing transcription factors (EMT-TF) by quantitative RT-PCR.

RESULTS

Patients with ≥ 5 CTCs/7.5 mL of peripheral blood 1 month after AHSCT had shorter progression-free survival (PFS) (P=0.02) and overall survival (OS) (P=0.02). Patients with apheresis products containing high percentages of CD326+ epithelial cells or overexpressing EMT-TF had shorter PFS. In multivariate analysis, low percentage of CD326+ epithelial cells and response to HDCT with AHSCT were associated with longer PFS, whereas lower CTCs after AHSCT was associated with longer OS. High CTCs, 1 month after AHSCT correlated with shorter PFS and OS in MBC patients undergoing HDCT and AHSCT, while CTCs with EMT and CSCs phenotype in apheresis products are associated with relapse.

CONCLUSION

Our data suggest that CTC and CTCs with EMT are prognostic in MBC patients undergoing HDCT followed by AHSCT.

Controversies in breast cancer: adjuvant and neoadjuvant therapy

Initial randomised studies of chemotherapy and endocrine therapy showed that systemic treatments had a substantial impact on the survival of women with early breast cancer. The original assumption was that the efficacy of these treatments was limited to those patients presenting with more adverse prognostic features. Subsequently, meta-analyses of randomised trials revealed that the benefits of chemotherapy and endocrine therapy are not mutually exclusive and extend to all the prognostic subgroups. However, the absolute benefit varies according to baseline characteristics such as tumour stage and other biological factors. Over the last 10 years, considerable progress has been made with the introduction of new drugs into the adjuvant and neoadjuvant treatment of women with breast cancer. Taxanes and third-generation aromatase inhibitors are providing proof of additional benefits compared with standard reference treatments. In parallel, research on the biology of breast cancer is establishing novel prognostic and predictive factors, which may allow better treatment tailoring. Currently, however, women with early breast cancer and their doctors face the difficult task of making therapeutic decisions often based on early results from positive studies. In a disease where follow up is crucial to fully assess the benefit and long-term toxicities of an intervention, current knowledge leaves unanswered questions that generate debate and controversy. This review will summarise recent results from randomised trials of adjuvant and neoadjuvant therapy in women with early breast cancer and focus on the current controversies.