Background
malignancy, tumor, cancer mortality [However, breast cancer, breast cancer
PEARLY DISEASE, TUMOR, CELLULAR PROLIFERATION, BREAST CANCER
Among women in the United States (US), breast cancer is the most commonly diagnosed malignancy and the second most common cause of cancer mortality [However, breast cancer is heterogeneous. Outcomes in patients diagnosed with early disease depend on a number of established prognostic and predictive factors such as hormone receptor status, human epidermal growth factor receptor 2 (HER2) status, tumor size, histologic grade, lymph node involvement, age, and molecular subtype [Window-of-opportunity (WOO) studies are nontherapeutic drug trials in which patients with newly diagnosed, early-stage breast cancer receive an investigational drug (alone or in combination with other drugs) for several days or weeks during the ‘window’ between diagnosis and primary surgery or neoadjuvant therapy [Changes in one or more biomarkers during the course of the study can be used to assess drug activity. The most commonly used biomarker in WOO studies is Ki67, which is a marker of cellular proliferation and a useful (although imperfect) predictor of treatment benefit and long-term survival outcomes [In studies of compounds that modulate ER signaling, it is also common to quantify their effects on ER, and sometimes also on progesterone receptors (PgRs). Although WOO studies do not replace trials that have clinical endpoints, they provide valuable data that may facilitate drug development and assist in clinical decision making [Amcenestrant (SAR439859) is a novel, optimized, oral, selective ER degrader (SERD) that antagonizes and degrades ERs [