Behavior of circulating tumor cells detected by EGF tagged SERS nanoparticles in head and neck cancer patients.

e21161 Background: Quantification of circulating tumor cells(CTCs) is becoming central to the management of metastatic breast, colorectal and prostate cancers and the potential to improve management of head and neck squamous cell cancer (HNSCC) patients is very high. Our group has published our experience with nanotechnology, highly specific, surface-enhanced Raman spectroscopy(SERS) and Epidermal Growth Factor Receptor(EGFR) ligands to identify 7-720 CTCs/ml in 19 samples from HNSCC patients[1]. Our goal here is to understand the clinical behavior of CTCs in HNSCC for selected patients whom we believe our single channel assay has been accurate. Methods: Our methods for detection of CTCs using EGFR ligands have been previously described[1]. After comparing CTCs in 116 patient samples with and without gross disease, we examined 8 patients with decreasing sequential single channel assays of CTCs and no evidence of disease at last follow-up. Results: For 56 samples from patients with no gross disease, the mean CTC was 94/ml. For 61 samples from patients with gross disease the mean CTC was 193/ml (p=0.002). Among our 4 samples where we had initial disease and a non-zero, no evidence of disease, second sample, the absolute and percentage decrease per month in CTC was 121/ml/month(range 43-160) and 17%/month(range 11-25%). The decrease of 121 CTC/ml/month correlated well with 5 out of 6 other data sets. Conclusions: Targeting of EGFR for detection of CTCs in HNSCC patients appears very promising. Among +EGFR HNSCC patients who appear cured, the average decrease in CTC per ml was 121 per month and 17% per month. To further enhance the sensitivity and specificity of detection of CTCs, we are developing 3 SERS nanoparticles (multiplexed SERS) to target specific and distinct targets on the CTC surface while still maintaining a single tube assay system. 1. Wang, X., et al., Detection of circulating tumor cells in human peripheral blood using surface-enhanced Raman scattering nanoparticles. Cancer Research, 2011. 71(5): p. 1526-32.