Abstract 1600: A multiplexed marker-based algorithm for diagnosis of carcinoma of unknown primary using circulating tumor cells

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Abstract: Real-time, single-cell multiplex immunophenotyping of circulating tumor cells (CTCs) is hypothesized to inform diagnosis of tissue of origin in patients with carcinoma of unknown primary (CUP). In 20 to 50% of CUP patients, the primary site remains unidentified, presenting a challenge for clinicians in diagnosis and treatment. Invasive tissue biopsy is the gold standard for diagnosis but improved methodology is needed. We developed a post-CellSearch CTC assay using multiplexed Q-dot or DyLight conjugated antibodies with the goal of detecting multiple markers in single cells within a CTC population. We adapted our approach to size-based CTC enrichment protocols for capturing CTCs and subsequent immunofluorescence (IF) using a minimal set of markers to predict the primary sites for common metastatic tumors. The carcinomas are diagnosed with cytokeratin 7 (CK7), cytokeratin 20 (CK20), thyroid transcription factor 1 (TTF-1), estrogen receptor (ER) or prostate-specific antigen (PSA) as the minimal set of informative markers. IF has been optimized in cultured tumor cells with individual antibodies, then with conjugated antibodies to form a multiplex antibody set. With IF, we evaluated antibodies specific to these 5 markers in lung, breast, colorectal, and prostate cancer cell lines and blood samples from metastatic prostate and breast cancer patients. Our technological advance provides a noninvasive, inexpensive, diagnostic blood test as an adjunct to routine tissue biopsy. Its further implementation requires prospective clinical testing. Citation Format: Elizabeth M. Matthew, Lanlan Zhou, Namrata Vijayvergia, David T. Dicker, Karen S. Gustafson, Harry S. Cooper, Eric A. Ross, Bora Lim, Ramdane Harouaka, Si-Yang Zheng, Nicholas E. Lamparella, Joseph J. Drabick, Cristina I. Truica, Zhaohai Yang, Wafik S. El-Deiry. A multiplexed marker-based algorithm for diagnosis of carcinoma of unknown primary using circulating tumor cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1600. doi:10.1158/1538-7445.AM2015-1600