Circulating tumor DNA - Current state of play and future perspectives.

Cancer management paradigms are shifting towards a personalized approach thanks to the advent of the -omics technologies. Liquid biopsies, consisting in the sampling of blood and other bodily fluids, are emerging as a valid alternative to circulating tumor biomarkers and tumor tissue biopsies for cancer diagnosis, routine monitoring and prognostication. The content of a liquid biopsy is referred to as the "tumor circulome". Among its components, circulating tumor DNA (ctDNA), including both cell-free and exosome-associated DNA, is the most widely characterized element. ctDNA analysis has a tremendous capability in the diagnostic arena. Its potential has been demonstrated at each level of disease staging and management and supported by a recent FDA approval for companion diagnostic, and the investments being made by pharmaceutical companies in this sector are numerous. The approaches available for ctDNA analysis allow both quantitative and qualitative studies and range from PCR and dPCR-mediated single/multiple gene mutational assessment to whole genome next generation sequencing and methylation mapping. Although the principal object of a liquid biopsy is blood, other body fluids such as urine and saliva show potential as complementary DNA sources for tumor analysis. In this review we provide a synopsis on the state of play of current ctDNA application. We discuss the clinical significance of ctDNA analysis and review the state of the art of technologies being currently developed to this aim. We also discuss the current issues limiting ctDNA application and highlight the promising approaches being developed to overcome these.

Multiple myeloma and persistence of drug resistance in the age of novel drugs (Review).

Multiple myeloma (MM) is a mature B cell neoplasm that results in multi-organ failure. The median age of onset, diverse clinical manifestations, heterogeneous survival rate, clonal evolution, intrinsic and acquired drug resistance have impact on the therapeutic management of the disease. Specifically, the emergence of multidrug resistance (MDR) during the course of treatment contributes significantly to treatment failure. The introduction of the immunomodulatory agents and proteasome inhibitors has seen an increase in overall patient survival, however, for the majority of patients, relapse remains inevitable with evidence that these agents, like the conventional chemotherapeutics are also subject to the development of MDR. Clinical management of patients with MM is currently compromised by lack of a suitable procedure to monitor the development of clinical drug resistance in individual patients. The current MM prognostic measures fail to pick the clonotypic tumor cells overexpressing drug efflux pumps, and invasive biopsy is insufficient in detecting sporadic tumors in the skeletal system. This review summarizes the challenges associated with treating the complex disease spectrum of myeloma, with an emphasis on the role of deleterious multidrug resistant clones orchestrating relapse.

Isolation of Human CD138(+) Microparticles from the Plasma of Patients with Multiple Myeloma.

The confinement of multiple myeloma (MM) to the bone marrow microenvironment requires an invasive bone marrow biopsy to monitor the malignant compartment. The existing clinical tools used to determine treatment response and tumor relapse are limited in sensitivity mainly because they indirectly measure tumor burden inside the bone marrow and fail to capture the patchy, multisite tumor infiltrates associated with MM. Microparticles (MPs) are 0.1- to 1.0-µm membrane vesicles, which contain the cellular content of their originating cell. MPs are functional mediators and convey prothrombotic, promalignant, proresistance, and proinflammatory messages, establishing intercellular cross talk and bypassing the need for direct cell-cell contact in many pathologies. In this study, we analyzed plasma cell-derived MPs (CD138(+)) from deidentified MM patients (n = 64) and normal subjects (n = 18) using flow cytometry. The morphology and size of the MPs were further analyzed using scanning electron microscopy. Our study shows the proof of a systemic signature of MPs in MM patients. We observed that the levels of MPs were significantly elevated in MM corresponding to the tumor burden. We provide the first evidence for the presence of MPs in the peripheral blood of MM patients with potential applications in personalized MM clinical monitoring.