Peter Schmid, MD, PhD, FRCP, Barts Cancer Institute, London, UK, talks on the results of a Phase II window of opportunity study of short-term preoperative treatment with enzalutamide in estrogen-receptor (ER)-positive and triple-negative breast cancer (TNBC). ER-positive patients either received enzalutamide and exemestane or exemestane alone, whereas the TNBC cohort all received single-agent enzalutamide. Addition of enzalutamide did not result in a significant reduction of Ki67 expression in the ER-positive and TNBC cohorts. Further translational research is underway to identify patients who will benefit from enzalutamide therapy. This interview took place at the European Society for Medical Oncology (ESMO) 2021 congress.