Prediction of exemestane benefit in patients with advanced breast cancer based on diagnostic biopsy mRNA analysis.

e12532Background: Exemestaneis a steroidal aromatase inhibitor used in the treatment of postmenopausal patients with estrogen receptor(ER)-positive adjuvant and advanced breast cancer. We aimed to determine the predictive value of a multigene mRNA-based mathematical algorithm (Drug Response Predictor (DRP)) for benefit of exemestane. The DRP is founded on measuring the full cancer transcriptome in sensitive and drug resistant cell lines compared with expression patterns in tumors and broadly validated in several studies (Wang et al. JNCI (2013) 105 (17): 1284-1291.) (Knudsen, S. et al. PLoS One (2014) 9(2): e87415.) (Christensen, TD et al. J Clin Oncol (2016) 34: suppl; abstr e12056.) (Kappel, IB et al. J Clin Oncol (2016) 34: suppl; abstr e20007.). Methods: Among 838 consecutive patients from a DBCG cohort with advanced breast cancer treated at 10 participating sites we identified 163 patients who between November 2008 and November 2015 initiated exemestane. All but one patient were ER-positive. Patients...