Liquid Biopsy: Current Status and Future Perspectives.

Cancer patients usually receive therapies according to their primary tumor's molecular traits. These characteristics may change during the molecular evolution of distant metastases as the leading cause of cancer deaths. Primary tumor tissue, if accessible at all, does not always provide enough information to stratify individual patients to the most promising therapy. Re-analysis of metastatic lesions by needle biopsy is possible but invasive, and limited by the known intra-patient heterogeneity of individual lesions. These hurdles might be overcome by analyzing tumor cells or tumor cell products in blood samples (liquid biopsy), which in principle might reflect all subclones present at that specific time point and allow sequential monitoring of disease evolution. Liquid biopsies inform on circulating tumor cells as well as tumor-derived cell-free nucleic acids, exosomes and platelets. Here, we introduce the different approaches of blood-based liquid biopsies and discuss the clinical applications in oncology.

Epithelial-mesenchymal plasticity in circulating tumor cells.

Epithelial-to-Mesenchymal Transition (EMT) is a complex process that supports the migratory capacity of epithelial tumor cells and is thought to play a crucial role in promoting cancer metastasis. Despite the wealth of experimental data, the exact role of EMT in cancer patients remains more controversial. Over the past 10 years, sensitive technologies that allow the detection and molecular characterization of circulating tumor cells (CTCs) in the peripheral blood of tumor patients have been developed. These analyses help to shed new light into the importance of EMT for human tumor cell dissemination. CTCs with mesenchymal features can be attributed in some clinical studies (in particularly on breast cancer) to higher disease stages, presence of metastases, and even to therapy response and worse outcome. However, the published studies addressing the impact of mesenchymal-like CTCs show heterogeneity with regard to assay specificity, size of cancer and control groups, and endpoint parameters. In the present review, we present the key features of the biology of CTCs in relation to epithelial-to-mesenchy-mal plasticity, describe the current technologies for enrichment and detection of CTCs with high epithelial-mesenchymal plasticity, and discuss the clinical studies that have assessed the relevance of mesenchymal CTCs in carcinoma patients.

Antibody production using a ciliate generates unusual antibody glycoforms displaying enhanced cell-killing activity.

Antibody glycosylation is a key parameter in the optimization of antibody therapeutics. Here, we describe the production of the anti-cancer monoclonal antibody rituximab in the unicellular ciliate, Tetrahymena thermophila. The resulting antibody demonstrated enhanced antibody-dependent cell-mediated cytotoxicity, which we attribute to unusual N-linked glycosylation. Detailed chromatographic and mass spectrometric analysis revealed afucosylated, oligomannose-type glycans, which, as a whole, displayed isomeric structures that deviate from the typical human counterparts, but whose branches were equivalent to fragments of metabolic intermediates observed in human glycoproteins. From the analysis of deposited crystal structures, we predict that the ciliate glycans adopt protein-carbohydrate interactions with the Fc domain that closely mimic those of native complex-type glycans. In addition, terminal glucose structures were identified that match biosynthetic precursors of human glycosylation. Our results suggest that ciliate-based expression systems offer a route to large-scale production of monoclonal antibodies exhibiting glycosylation that imparts enhanced cell killing activity.