One potential explanation for the variation in outcome may be due to differential response in different BC subtypes, as shown in two neoadjuvant clinical trials with Bev; one reported increased response rates in the triple negative BC subset (von Minckwitz et al., 2012), whereas the other reported most responding patients in the estrogen receptor (ER)‐positive BC patients (Bear et al., 2012). This evidence concerns the gene ESR1 and breast cancer.