Feasibility of finding circulating tumors cells and assigning PD-L1 receptor status using single-cell technology combined with Celsee Genesis system.

Abstract

567 Background: enumerating circulating tumor cells (CTC) may improve our ability to differentiate between localized and metastatic bladder cancer (BC) and predict response to systemic therapies. However, previously used CTC identification platforms had limited utility in managing patients diagnosed with this disease because they lacked the appropriate sensitivity level. Also, they did not report on the PD-L1 receptor status, which is becoming an essential component of modern immunotherapy of BC. Methods: We used a novel device to enrich and retrieve CTCs from blood samples of patients with high grade and low-grade BC, as well as benign conditions, treated with cystectomy by using a microfluidic chip. The Celsee Genesis (Celsee Inc) captures CTCs with high sensitivity and allows the captured CTCs to be retrieved for molecular analysis. It uses the microfluidic chip, which has approximately 56,320 capture chambers. Based on differences in cell size and deformability, each chamber ensures that small blood cells escape while larger CTCs of varying sizes are trapped and isolated in the chambers. PD-L1 expression on the isolated tumor cells was then evaluated using 4-color single-cell technology (IncellDX Inc.) directly on the chip. Results: Ten bladder cancer (5 low grade (LG) and 5 high grade (HG) disease) and two benign bladder pathology patients provided blood samples before their cystectomy. Circulating tumor cells were found in 3 patients (two LG and one HG disease). CTCs were four times higher in the HG sample than in the LG samples. PD-L1 expression was high on CTCs isolated from the HG patient’s blood sample and lower in the two LG blood samples. No CTCs were detected in patients with benign bladder pathology. Conclusions: Our results show the feasibility of using novel, high sensitivity CTC detection and PD-L1 single cell measuring technology in patients with BC. We also show that this technology has a potentially high sensitivity level for detecting CTC in patients with bladder malignancies by detecting low levels of CTCs in low-grade disease. More extensive studies are planned to validate our findings.