Short-term Preoperative Treatment With Enzalutamide, Alone or in Combination With Exemestane in Primary Breast Cancer

Open-label, international, multicentre window of opportunity phase II trial to evaluate the effects of short-term preoperative therapy with enzalutamide (alone or in combination with exemestane) in women with newly diagnosed invasive primary breast cancer. The study has two cohorts: * ER+ve breast cancer * AR+ve, Triple-negative (i.e. ER-negative, PR-negative and HER2-negative) breast cancer Study treatment is planned for a minimum of 15 days and a maximum of 29 days unless there is evidence of unacceptable toxicity or the patient requests to be withdrawn from the trial. Thereafter, patients will either be considered for definitive surgery or primary medical treatment (e.g. neoadjuvant chemotherapy) at the discretion of the treating physician. The effects of enzalutamide (alone or in combination with exemestane) will be assessed on tumour tissue specimens taken at baseline and on the last day of study treatment.