Detection of Circulating Plasma Cells in Multiple Myeloma

Abstract

The “liquid biopsy,” which focuses on the analysis of circulating tumor cells (CTCs)4 in blood of cancer patients, has received enormous attention because of its obvious clinical implications for personalized medicine (1). Analyses of CTCs have paved new diagnostic avenues in patients with carcinomas (in particular, breast and prostate cancer), including detection of cancer, prediction of prognosis in patients with curable disease, monitoring systemic therapies, and stratification of patients based on the detection of therapeutic targets or resistance mechanisms. In contrast, CTC analyses in patients with multiple myeloma (MM) are still in their infancy despite encouraging previous reports (2) and the fact that MM accounts for 13% of all hematological malignancies, with approximately 86000 new cases per year worldwide. The limited analytical sensitivity of multiparameter flow cytometry restricts this technology to the analyses of bone marrow (BM) where plasma cells reside. However, BM analysis is invasive, and the analysis of peripheral blood as a “liquid biopsy” may therefore complement or minimize BM analyses in the future treatment of MM patients. The potential for CD138-based microfluidic cell capture, as an analytically sensitive tool to monitor residual disease in MM during and after treatment by sequential blood analyses, might be a promising outlook. Recently, Qasaimeh et al. published new data on the isolation of circulating plasma cells (CPCs) in multiple myeloma (3) using a microfluidic device that is the size of a standard glass slide. CPCs were captured by the marker CD138 that is highly expressed on the membrane of plasma cells and specific for these cells within the hematopoietic system. The …