A Phase-3, Open-Label, Randomized Study of Dato-DXd Versus Investigator's Choice of Chemotherapy (ICC) in Participants With Inoperable or Metastatic HR-Positive, HER2-Negative Breast Cancer Who Have Been Treated With One or Two Prior Lines of Systemic Chemotherapy (TROPION-Breast01)

The primary objective of this study will assess the safety and efficacy of datopotamab deruxtecan (Dato-DXd) in participants with inoperable or metastatic HR-positive, HER2-negative breast cancer who have been treated with one or two prior lines of systemic chemotherapy. The study will be stratified based on number of previous lines of chemotherapy (1 vs. 2), prior use of CDK4/6 inhibitors (Yes vs. no) and geographic region of participant (US/Canada/Europe vs. rest of world). This study aims to see if datopotamab deruxtecan allows patients to live longer without their breast cancer getting worse, or simply to live longer, compared to patients receiving standard of care chemotherapy. This study is also looking to see how the treatment and the breast cancer affects patients' quality of life.