AUA 2017: Detection of Circulating Tumor Cell in the Patients with Prostate Cancer Using Novel Viral Marker OBP-1101

Boston, MA ( Dr. Hinata and colleagues from Japan presented their early work detecting circulating tumor cells (CTC) in patients with prostate cancer using a novel viral marker at the ‘Late-Breaking Abstract’ session at today’s 2017 AUA Annual meeting. Certainly over the last few years there has been increasing interest in the prognostication of CTCs, particularly in the advanced prostate cancer arena. The authors note, however, that CTC detection by using immunohistochemical techniques has limitations, such as dead cancer cells being detected (false positives), insufficient sensitivity, and inability to detect epithelial mesenchymal transformation (EMT).

To perform this study, the authors enrolled 49 patients in a prospective trial, collecting 15 mL of blood from each patient and then using OBP-1011 to detect CTCs. OBP-1011 is a novel adenovirus derived for detection of cancer cells by using Green Fluorescent Protein (GFP), the expression for which is controlled by a telomerase promoter in OBP-1101. GFP was positive in 26 cases (53%), and the antibody EpCAM was positive in 28 cases (57%). Among these specific 28 cases, PSMA was positive in 25 cases (89%), whereas only 8% of patients in the entire cohort had solely PSMA positivity. Neither clinical stage, Gleason score, PSA, or NCCN risk classification correlated with GFP positivity or EpCAM positivity. The strength of this study is the novelty with which to attempt to further delineate true CTCs in an attempt to decrease the false positive rate.

The authors concluded that CTCs detected by using the viral marker OBP-1101 may have different characteristics from those detected using epithelial markers. This is exciting research, but clearly external validation and outcomes from larger cohorts are necessary prior to widespread adoption.

Speaker: Nobuyuki Hinata, Kobe University Graduate School of Medicine, Kobe, Japan

Co-Authors: Yukari Bando, Akira Miyazaki, Tomoaki Terakawa, Junya Furukawa, Kenichi Harada, Masato Fujisawa

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre
Twitter: @zklaassen_md

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA