1029P - Circulating Tumor Cells (CTCS) in Patients with Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (HNSCC): Frequency, Clinical Significance and EGFR Expression

Abstract

ABSTRACT Introduction Recurrent/metastatic (R/M) HNSCC have a poor prognosis. Palliative chemotherapy is often used without adequate prognostic and predictive stratification due to the lack of validated predictors in this setting. Furthermore, anti-EGFR therapy is used under the assumption that more than 80% of the primary tumors overexpresses EGFR. CTCs have been identified as prognostic and predictive indicators in several metastatic cancers. We prospectively studied the frequency, clinical significance and EGFR expression of CTCs in pts with R/M HNSCC. Patients and methods Pts with local and/or distant relapse of HNSCC at first or second relapse were included between January 2009 and December 2011. CTCs were measured at baseline and at end of treatment or progression. CTCs analysis was performed with the CellSearch® system. The diagnostic performance of the system with squamous cancer cells was tested with cell lines spiking experiments. The CellSearch® fourth channel was used to analyze EGFR expression on CTCs. Results Fifty-three pts were evaluable for CTCs analysis and clinical response. CTCs were detected in 14 (26%) pts at baseline and in 22 (41%) pts at any time point. Median CTCs number was 1 CTC/7.5 mL. CTCs were not associated to any of the clinico-pathological variables considered. EGFR was expressed in 45% of CTC-positive pts. After treatment, CTC numbers decreased, remained stable and increased in 8%, 54% and 38% of pts, respectively. Baseline CTCs or their increase were predictive of stable or progressive disease (p .007). In 42 evaluable pts, baseline CTCs were prognostic indicators of worse progression-free (PFS) (3 vs 8 months, p .003) and overall (OS) (5 vs 10 months, p .013) survivals, respectively. Conclusion This study demonstrates that: a) low numbers of CTCs are detectable by CellSearch® in more than 40% of R/M HNSCC pts; b) CTCs at baseline or at any time point are independent predictors of poor PFS and OS; c) presence of CTCs during treatment is predictive of chemo-resistant disease; d) EGFR is expressed on CTCs with a high intra-sample and inter-patient variability. These results encourage further development of CTCs in this setting. Disclosure All authors have declared no conflicts of interest.