Stem cells in breast tumours: Are they ready for the clinic?

The concept of stem-like cells in cancer has been gaining currency over the last decade or so since evidence for stem cell activity in human leukaemia and solid tumours, including breast cancer, was first published. The evidence established that sub-populations of cells identified by antibodies to cell surface markers behaved like developmental stem cells in their capacity to re-grow the human tumour for several generations in experimental immune-deficient hosts. The experiments established that cells with tumourigenic capacity expressed ‘cancer stem cell’ (CSC) markers and that activity could also be measured by self-renewal of tumour sphere colonies in culture. In breast and other cancers, there is good evidence that CSCs are relatively resistant to radio- and chemotherapy indicating that novel CSC-targeted therapies are needed. Several pathways are promising targets in breast CSCs. There are several ways of combating CSC activity including inducing their apoptosis, inhibiting stem cell self-renewal to either stop their division or to promote their differentiation, or targeting the CSC niche that supports them. The first challenge for developing novel CSC therapies is to ascertain which of these CSC properties is being targeted. The second challenge is to determine suitable CSC biomarkers to measure the efficacy of the novel CSC therapies. We propose using biomarkers as a means to identify and assess CSC activity in clinical trials. This is likely to be demanding but feasible in the near future. Thus, we asked if CSCs are ready for the clinic, however, the emerging question becomes: is the clinic ready for cancer stem cells?     

Molecular profiling assays in breast cancer: are we ready for prime time?

Breast cancer is a heterogeneous disease with diverse morphologies, molecular characteristics, and clinical behavior. The advances in molecular profiling technologies have changed our understanding of breast cancer and led to the identification of prognostic/predictive gene signatures. Despite the huge quantity of information gleaned from these profiling technologies and the increasing number of gene signatures, their incorporation into clinical decision making is a slow process and is limited in various aspects. The 70-gene assay (MammaPrint, Agendia, Netherlands) and the 21-gene assay (Oncotype DX, Genomic Health, USA) are the most widely used breast cancer multigene classifier assays. A 50-gene assay (PAM50, NanoString, USA) has shown promise but needs further independent validation. In this review, we will present the current data on commercially available molecular profiling assays in breast cancer and discuss the challenges surrounding their incorporation into routine clinical practice as prognostic and predictive tools.     

Circulating tumor DNA analysis in breast cancer: Is it ready for prime-time?

Precision Medicine is becoming the new paradigm in healthcare as it enables better resources allocation, treatment optimization with a potential side-effects reduction and consequent impact on quality of life and survival. This revolution is being catalyzed by liquid biopsy technologies, which provide prognostic and predictive information for advanced cancer patients, without the analytical and procedural drawbacks of tissue-biopsy. In particular, circulating tumor DNA (ctDNA) is gaining momentum as a clinically feasible option capable to capture both spatial and temporal tumor heterogeneity.Several techniques are currently available for ctDNA extraction and analysis, each with its preferential case scenarios and preanalytical implications which must be taken into consideration to effectively support clinical decision-making and to better highlight its clinical utility.Aim of this review is to summarize both analytical developments and clinical evidences to offer a comprehensive update on the deployment of ctDNA in breast cancer’s (BC) characterization and treatment.