Abstract 3630: Non-enrichment based method for analysis of androgen receptor expression in circulating tumor cells (CTCs) in patients with metastatic castrate resistant prostate cancer

• Published in: Cancer research (Chicago, Ill.) Ill.), 2012-04, Vol.72 (8_Supplement), p.3630-3630
• Main Authors: Gross, Mitchell E., Lazar, Daniel C., Cho, Edward H., Luttgen, Madelyn, Uson, Maria L., Kuhn, Peter, Torrey, Melissa L.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2012-3630

Background: We have established a fluid phase biopsy approach that identifies CTCs which preserves cytologic features in high-definition (HD) for diagnostic pathology without using immune or surface receptor-based enrichment. HD-CTCs identified with this approach can be used for enumeration and molecular characterization. Methods: Blood was collected from metastatic prostate cancer patients and normal donors in Cyto-Chex® tubes (Streck, Omaha, NE) as part of IRB approved protocols at each site. Following erythrocyte lysis, 3 million nucleated cells were deposited on a glass slide. Samples were incubated with a pan-cytokeratin (CK), CD45, and androgen receptor (AR) antibodies and counter-stained with DAPI. LNCaP cells were spiked into normal blood. Images were obtained with a fluorescent scanning microscope and analyzed with a computer algorithm. Candidate HD-CTCs were subsequently verified by expert readers. Slides were re-imaged for quantitative analysis using at a fixed exposure and gain. Results: A total of 227 CTCs from ten patients were compared to 20 LNCaP cells. The median (range) HD-CTCs in this cohort was: 9 (1-62) cells/ml. The mean ± standard deviation measurements in HD-CTCs were observed: CK intensity 60.4±154; total cell area 89.0 ± 53.8 μm2; nuclear area 61.1 ± 36.0 μm2. LNCaP cells spiked into normal blood gave the following values: CK intensity 1166+/−306; total cell area 143 ± 48.1 μm2; nuclear area 63.1 ± 18.6 μm2. CTCs were additionally classified as either AR positive (AR+) or AR negative (AR-). 37 of the 227 (16.3%) HD-CTCs were AR+. The average CK intensity was significantly higher in AR+ versus AR- cells at 174.23 and 39.86, respectively (p