A prospective comparison of ER, PR, Ki67 and gene expression in paired sequential core biopsies of primary, untreated breast cancer

Sirwan M Hadad,Stacy L Moulder-Thompson,Lee B Jordan,Colin A Purdie,Pankaj G Roy,Alastair M Thompson,Takayuki Iwamoto,Lajos Pusztai

doi:10.1186/s12885-016-2788-x

Abstract

BackgroundSequential biopsy of breast cancer is used to assess biomarker effects and drug efficacy. The preoperative “window of opportunity” setting is advantageous to test biomarker changes in response to therapeutic agents in previously untreated primary cancers. This study tested the consistency over time of paired, sequential biomarker measurements on primary, operable breast cancer in the absence of drug therapy.MethodsImmunohistochemistry was performed for ER, PR and Ki67 on paired preoperative/operative tumor samples taken from untreated patients within 2 weeks of each other. Microarray analysis on mRNA extracted from formalin fixed paraffin embedded cores was performed using Affymetrix based arrays on paired core biopsies analysed using Ingenuity Pathway Analysis (IPA) and Gene Set Analysis (GSA).ResultsIn 41 core/resection pairs, the recognised trend to lower ER, PR and Ki67 score on resected material was confirmed. Concordance for ER, PR and Ki67 without changing biomarker status (e.g. ER+ to ER-) was 90, 74 and 80 % respectively. However, in 23 paired core samples (diagnostic core v on table core), Ki67 using a cut off of 13.25 % was concordant in 22/23 (96 %) and differences in ER and PR immunohistochemistry by Allred or Quickscore between the pairs did not impact hormone receptor status. IPA and GSA demonstrated substantial gene expression changes between paired cores at the mRNA level, including reduced expression of ER pathway analysis on the second core, despite the absence of drug intervention.ConclusionsSequential core biopsies of primary breast cancer (but not core versus resection) was consistent and is appropriate to assess the effects of drug therapy in vivo on ER, PR and Ki67 using immunohistochemistry. Conversely, studies utilising mRNA expression may require non-treatment controls to distinguish therapeutic from biopsy differences.

Highlights

Sequential biopsy of breast cancer is used to assess biomarker effects and drug efficacy
Other studies have demonstrated changes in gene expression associated with response to neoadjuvant therapy [20] signatures of response to chemotherapy have to date been rare [21]
This study examined paired primary breast cancer biopsies with a 2 week interval between sampling, using immunohistochemistry for estrogen receptor alpha (ER), progesterone receptor (PR) and Ki67 and Messenger RNA (mRNA) gene expression

Summary

Introduction

Sequential biopsy of breast cancer is used to assess biomarker effects and drug efficacy. Biomarker studies based on the use of core biopsy and/ or resection specimens for translational research in breast cancer are useful to evaluate effects of therapeutic intervention in neoadjuvant, pre-surgical and metastatic studies. Sequential tumor core biopsy has become accepted in neoadjuvant and window of opportunity studies to seek early evidence of therapeutic efficacy [11,12,13]. This has included neoadjuvant endocrine trials [14, 15] and novel agents [13] or repurposing drugs [12, 16] in window of opportunity studies. Other studies have demonstrated changes in gene expression associated with response to neoadjuvant therapy [20] signatures of response to chemotherapy have to date been rare [21]

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Discussion

Conclusion