Prediction of fulvestrant efficacy in patients with advanced breast cancer: retrospective-prospective evaluation of the predictive potential of a multigene expression assay

Background Fulvestrant is a selective oestrogen receptor (ER) degrader used as monotherapy and combination therapy for ER positive HER2 negative advanced breast cancer (ABC) in postmenopausal women. The drug response predictor (DRP), is a mathematical algorithm based on the expression of multiple genes in the tumour. The fulvestrant DRP algorithm has previously shown effect in BC. In this study, we investigated the DRP’s potential in predicting fulvestrant benefit.