Circulating tumor cell (CTC) is a potentially useful surrogate of micro-metastasis, but detection of rare tumor cells contaminated in a vast majority of normal hematologic cells remains technical challenges. To achieve effective detection of a variety of CTCs, we have developed a novel microfluidic system (CTC-chip) in which any antibody to capture CTCs is easily conjugated. In previous studies, we employed an antibody (clone E-1) against podoplanin that was strongly expressed on mesothelioma cells. The CTC-chip coated by the E-1 antibody (E1-chip) provided a modest sensitivity in detection of CTCs in malignant pleural mesothelioma (MPM). Here, to achieve a higher sensitivity, we employed a novel anti-podoplanin antibody (clone NZ-1.2). In an experimental model, MPM cells with high podoplanin expression were effectively captured with the CTC-chip coated by the NZ-1.2 antibody (NZ1.2-chip). Next, we evaluated CTCs in the peripheral blood sampled from 22 MPM patients using the NZ1.2-chip and the E1-chip. One or more CTCs were detected in 15 patients (68.2%) with the NZ1.2-chip, whereas only in 10 patients (45.5%) with the E1-chip. Of noted, in most (92.3%, 12/13) patients with epithelioid MPM subtype, CTCs were positive with the NZ1.2-chip. The CTC-count detected with the NZ1.2-chip was significantly higher than that with the E1-chip (p = 0.034). The clinical implications of CTCs detected with the NZ1.2-chip will be examined in a future study.
Detection of circulating tumor cells with a novel microfluidic system in malignant pleural mesothelioma