402P - Circulating Tumor Cells Analysed By Scanning Fluorescence Microscopy in the Xena Trial

Abstract

ABSTRACT Aim: The hypothesis is that circulating tumor cells (CTC) can be used as an indicator for treatment response in metastatic breast cancer patients. CTC results from the first 38 patients in a monitoring study are presented. Methods: CTC are tested as a monitoring marker for treatment response in the clinical trial XeNa. Metastatic or locally advanced HER2 negative breast cancer patients are treated with a combined therapy with Xeloda and Navelbine Oral vs standard of care treatment. We aim to include 120 breast cancer patients in a randomized two-armed study with equal numbers in each arm. Blood samples before treatment and approximately four weeks after first treatment will be analyzed for CTC by a scanning fluorescence microscope (CytoTrack®). Details regarding XeNa can be found at clinicaltrials.org, ClinicalTrials.gov Identifier: NCT01941771. The endpoints of the study includes overall survival, clinical response according to RECIST criteria and clinical response according to CTC count. The null hypothesis is that there is no difference in outcome for patients with CTC compared to patients without CTC. It is estimated that with a power of 0.80, a total of 80 patients are required to reject the null hypothesis with a significance level of 0.05. CTC analysis is performed by the scanning fluorescence microscope CytoTrack. Results: In 38 consecutive patients, 17 were found positive for CTC prior to treatment. Follow up samples were CTC positive in twelve of the original CTC positive patients and CTC negative in five of the original CTC positive patients. Twentyfour patients had no CTC prior to or following treatment. The study is ongoing, so outcome for the patients are not yet known. No of patients Median prior Range prior Median Post Range post No CTC 24 0 0 0 0 CTC unchanged 12 17 2-36 0 0 CTC decreased 5 4 2-77 4 2-49 Conclusions: CTC analysis is regarded as a promising marker for monitoring treatment effect in metastatic breast cancer. The utility of CTC in monitoring treatment response and residual disease in the current study will become more clear when the study is completed and the patient outcome is known. Disclosure: All authors have declared no conflicts of interest.