Abstract CN02-02: CTCs as pharmacodynamic and /or predictive biomarkers

CTC analysis has potential utility in the development of novel therapeutics and particularly so for the management of those patients with cancer types for which obtaining tumor biopsies poses significant challenge, especially pre and serially post therapy. We have enumerated and begun to characterize CTCs from patients with lung cancer (both small cell lung cancer (SCLC) and non small cell lung cancer (NSCLC)) using two techniques; a) the Veridex CellSearch Platform wherein CTCs are identified based on EpCam and cytokeratin expression together with the absence of the white blood cell surface marker CD45, and b) the Metagenex ISET filter‐based system that isolates CTCs on the basis of their size. SCLC accounts for ∼15% of all lung cancers, is highly aggressive with a rapid doubling time, high growth fraction and propensity to metastasise early. Primary SCLC biopsies are often of small volume, highly necrotic and thus present difficulties for biomarker analysis. As SCLC has neuro‐endocrine characteristics, we examined initially, the ability of the CellSearch approach (with the epithelial cell marker EpCam as its primary discriminator) to detect SCLC CTCs. In chemo‐naive SCLC, CTCs were detected in 86% patients (median 28, range 0–44896, n=50). Tumor stage correlated with CTC number (#) and was highest in patients with liver metastases. The median survival for patients with baseline CTC# >300/7.5ml blood was 134 days compared to 443 days when CTC# 5 at baseline predicted for a worse progression free and overall survival compared to patients with Citation Information: Mol Cancer Ther 2009;8(12 Suppl):CN02-02.