Liquidscan mediated HER2 amplification detection in patient samples study.

e13016 Background: Overexpression of HER2 serves as an oncogenic driver in breast cancer which can result in tumor progression and distant metastases. Amplification or overexpression of HER2 occurs in approximately 15–30% of breast cancers and serves as a therapeutic, prognostic and predictive biomarker. There have been tremendous advances in HER2+ breast cancer management and there is an need to identify patients with HER2+ early breast cancer who may benefit from de-escalation or escalation of treatment. In addition, selection of HER2 therapies beyond the 2 nd line setting for HER2+ metastatic breast cancer is currently unclear. Therefore, rapid monitoring tests for treatment response are needed. Liquid biopsy may provide a cost effective, sensitive, and non-invasive approach to monitor response. Methods: Whole blood (8ml) from 20 consenting patients with confirmed stage 3 or 4 metastatic breast cancer with clinical Her2 status identified by solid tissue biopsy (10 HER2+ and 10 HER2-) were collected. Circulating tumor cells were isolated on the LiquidScan system, were probed by HER2 FISH, analyzed using automated and visual microscopy. Results: Protocols were optimized to obtain morphology and cellularity of the tumor cells allowing conclusive HER2 identification for all samples. All samples from patients identified as Her2+ by standard invasive solid tumor biopsies could be identified (100% concordance), whereas for one sample that was reported as HER2-, cells were identified with the liquid biopsy having HER2+ FISH morphology. Further molecular analysis on this patient is under way. Conclusions: We were able to demonstrate that non-invasive liquid biopsy with the LiquidScan identifies HER2 status. The method has high concordance with conventional solid biopsy approach and may be a promising for patient monitoring. We will expand to larger sample sets to explore the full capacity of liquid biopsy to monitor and diagnose HER2 related diseases.