Characterization of HER2 functional profiling in fine needle aspirates (FNA) in patients with metastatic breast cancer (MBC).

Abstract

e21029 Background: The Collaborative Proximity Immunoassay (COPIA) is a multiplexed microarray platform that utilizes the formation of a unique immuno-complex requiring co-localization of two detector-antibodies. The detector-antibodies are conjugated with corresponding channeling-enzymes for proximity mediated signal generation/amplification for the expression and activation profiling of HER1, HER2, p95HER2, HER3, IGF1-R, c-MET, PI3K, Shc, VEGFR, CK, and other signal transduction proteins. Here we report HER2 expression and activation profiling in fine needle aspirate (FNA) biopsy samples from MBC patients in an ongoing investigation with this novel technology. Methods: FNA samples were collected from metastatic sites from female patients with progressive, Stage IIIB/IV breast cancer (n = 25, baseline age 42 ± 13yr). Patients with various clinical primary ER/PR/HER2 statuses by IHC staining were allowed in the study. The ER/PR/HER2 status of the primary tumor sample was obtained by the local sites. Expression and activation status for HER2 and the other signal transduction Proteins (STP) were measured using COPIA on FNA samples. Results: Data from the FNA samples of the first 10 patients showed that 5 (50%) were HER2 activated (pHER2+), 2 (20%) were HER2 over-expressed (tHER2+), pHER2+ and p95HER2 over-expressed. 7 of 10 FNA samples expressed weak to moderate levels of tHER2 with different pHER2 levels. HER2 status (expression/activation) was negative in 1 patient. The concordance between the COPIA-derived data from the FNA and the primary tumor IHC will be evaluated. In addition, over-expression and/or activation of other STP including HER1, HER3, IGF1- R, c-MET will be measured in the entire cohort using COPIA. Conclusions: COPIA assays can be used to quantitate expression and activation of STPs in FNA specimens. These results need to be further analyzed for their potential value to inform treatment decisions in relapsed breast cancer patients. No significant financial relationships to disclose.