Centrally confirmed grade 3 invasive ductal ER+/HER2- malignant BC patients (T1c-2 (≥2 cm), cN1-2, or T3–4 cN0-2) were randomized 1:1 to receive either neoadjuvant pembrolizumab 200 mg Q3W or placebo. This evidence concerns the gene ESR1 and breast cancer.