Abstract 1589: Investigation of circulating tumor cells from head and neck cancer patients undergoing radiation therapy: A pilot study

Abstract

Abstract Background: Circulating tumor cell (CTC) enumeration provides prognostic information in patients with metastatic breast, prostate, colorectal and lung cancer. However, the effect of radiation therapy (RT) on CTCs in patients with primary head and neck malignancies has not been explored. The purpose of this exploratory study is to examine how CTCs, as measured by a novel cell capture technique, respond to RT in patients with head and neck cancer. Methods: A total of a 16 patients undergoing definitive radiation for primary, non-metastatic head and neck cancer were enrolled in this pilot study. Peripheral blood was collected at 5 time points, including at baseline prior to starting RT, at the first week, mid-point and final week during treatment, and at least 4 weeks after completion of RT. Quantification of CTCs was performed with a novel device that used a biomimetic combination of three cancer cell-specific antibodies (aEpCAM, aHer-2, and aEGFR) immobilized through poly(amidoamine) dendrimers and E-selectin, which respectively induce concurrent stationary binding and dynamic cell rolling of the tumor cells. Results: CTCs were successfully detected in all patients before the start of radiation (100%), including patients with HPV/p16 positive or negative tumors. The novel CTC device yielded up to a 4-fold enhancement in capture efficiency relative to the aEpCAM-functionalized surface. The average CTC count in patients before RT was 386 CTCs per mL (range, 18 to 1134 CTCs per mL), significantly higher than the average CTC count of 90 CTCs per mL after the completion of radiation (range, 5 to 393 CTCs per mL). All but one patient demonstrated a decrease in measured CTCs at sequential time points during the course of RT. The patient with an elevation in CTCs during RT had residual metastatic carcinoma detected after left level II selective cervical neck dissection, which was performed 12 weeks post-RT due to persistent radiographic lymph nodal abnormality. At a median follow-up of 1.5 months, no patient has had a local or distant failure. Conclusions: We have demonstrated that our novel technology can affectively capture CTCs in head and neck cancer patients. Importantly, our pilot data shows CTCs decrease over the course of RT, suggesting CTCs can be a predicative biomarker for radiotherapy response. Further study will investigate associations between CTC kinetics and clinical outcomes. Citation Format: Michael J. Eblan, Ja Hye Myung, Joseph M. Caster, Bhishamjit S. Chera, Seungpyo Hong, Andrew Z. Wang. Investigation of circulating tumor cells from head and neck cancer patients undergoing radiation therapy: A pilot study. [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 1589. doi:10.1158/1538-7445.AM2015-1589