Abstract B98: Serial evaluation of PD-L1 expression on circulating tumor cells (CTCs)

BACKGROUND: Metastatic non-small cell lung cancer (NSCLC) tumors have adopted methods to evade immune detection and/or clearance. This can occur via overexpression of programmed cell death ligand 1 (PD-L1). Response rate, progression free survival and overall survival with PD-1 inhibitors are greater in tumors with high tumor PD-L1 expression (Garon et al, NEJM 2015, Paz-Ares et al, ASCO 2015). There has been interest in using PD-L1 tumor expression as a treatment selection criterion. Currently available methods of screening involve invasive tumor biopsy followed by histological grading of PD-L1 levels. Biopsies allow sampling from limited sections of the tumor, which may miss heterogeneity. CTC PD-L1 levels could aid in screening patients, and could supplement tissue PD-L1 biopsy results by evaluating a representative sampling from multiple tumor sites which shed cells into the blood. Additionally, following PD-L1 levels on CTCs serially over time may potentially yield information about modulation of tumor PD-L1 expression in the presence of PD-1 or PD-L1 antibodies or other anti-cancer agents.METHODS: We have developed a microfluidic device for rapid, size-based capture of CTCs from blood called Vortex HT chip. The Vortex HT chip utilizes inertial microfluidic flows to isolate CTCs with capture efficiency up to 40% and high purity (>80%). We used the Vortex HT device to capture CTCs from NSCLC patients undergoing PD-1 immunotherapies, both prior to initiating treatment a...
Source: Molecular Cancer Therapeutics - Category: Cancer & Oncology Authors: Tags: Immune Monitoring/Clinical Correlates: Poster Presentations - Proffered Abstracts Source Type: research