[308] Microarray Based Determination of ER, PR and HER2 Receptor Status Compared to Local IHC/FISH Assessment

G Seitz, J Palacios, JM Guinebretiere, E Lienen, P Roepman, L Stork-Sloots, R Bender, Y Tokunaga, T Watanabe. Institute of Pathology, Bamberg, Germany; Hospitales Universitarios Virgen del Rocio, Sevilla, Spain; Centre Rene Huguenin, Saint-Cloud, France; Agendia BV and Agendia Inc, Huntighton Beach, CA; Hamamatsu Oncology Center, Hamamatsu, Japan

Background: The level of estrogen receptor (ER), progesterone receptor (PR) and HER2 expression is predictive for prognosis and/or treatment response in breast cancer patients. However, differences in fixation and IHC and subjective interpretation can substantially affect the accuracy and reproducibility of the results. The recently developed TargetPrint test measures the mRNA expression level of ER, PR and HER2 and provides an objective and standardized alternative to IHC. This study compares results from the microarray-based (MA) TargetPrint with IHC and FISH generated by local standard procedures.
Design: Material and methods: Prospective tumor samples were collected for 53 patients diagnosed with breast cancer stage I to III between 12/08 and 08/09. The mRNA level of ER, PR and HER2 and the MammaPrint risk analysis were assessed in a central laboratory (Agendia BV, Amsterdam) in fresh tumor samples submitted from 3 European and 1 Japanese hospital: The results of the IHC/FISH assessments performed according to the local standards at the hospitals were compared to the quantitative gene expression readouts.
Results: Of the 53 samples 4 samples were ineligible for gene expression profiling. In the remaining 49 samples, 1 had insufficient RNA quality and 48 (98%) could successfully be hybridized. Median age of these patients was 60.4 years. Among the 48 patients, 19 (40%) were classified as good prognosis, whereas 29 (60%) were classified as poor prognosis. Comparison of IHC and MA showed a concordance of 92% for ER; 83% for PR and 92% for HER2. Submitted from Bamberg, 5 of 11 patients assessed by IHC and MA had initially a discordant PR result. Re-analysis of all patients using a new antibody for the PR staining confirmed the microarray results in 4 patients.
Conclusions: Microarray based readout of ER, PR and HER2 status using TargetPrint is highly comparable to local IHC and FISH analysis on retrospectively and prospectively analyzed samples in various hospitals. Moreover, TargetPrint confirmed a suspected PR staining problem in one hospital suggesting that TargetPrint microarray readouts for hormone and HER2 receptor status in addition to standard IHC can improve the molecular characterization of breast cancer tissue.
Category: Breast

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 12, Tuesday Afternoon


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