Characterization and prognostic significance of circulating tumor cells in the peripheral blood of patients with metastatic pancreatic cancer.

4127 Background: Increased numbers of circulating tumor cells (CTC) are associated with worse survival in patients (pts) with metastatic prostate, breast, and colorectal cancer. We initiated the current pilot study to evaluate the clinical significance and characteristics of CTC in pts with metastatic pancreatic cancer (mPC). Methods: The CellSearch immunomagnetic separation system was used to quantify CTC from the peripheral blood of pts with mPC on first-line systemic therapy. Samples were evaluated at baseline, 7 days, and first disease evaluation (6-10 weeks). CTC were further analyzed for epidermal growth factor receptor (EGFR) and human mucin 1 (MUC1) expression utilizing immunofluorescent markers. Results: 40 pts were enrolled. Pt characteristics: M/F (24/16), age range 39-86 years (median 61). 50% of pts at baseline (median 0.5, range 0-20), 39% at 7 days, and 28% at 6-10 weeks had ≥ 1 CTC/7.5mL peripheral blood. Median progression-free survival (PFS) and overall survival (OS) were 113 and 232 day...