A Phase III Study of Dato-DXd With or Without Durvalumab Compared With Investigator's Choice of Chemotherapy in Combination With Pembrolizumab in Patients With PD-L1 Positive Locally Recurrent Inoperable or Metastatic Triple-negative Breast Cancer

The primary objective of the study is to demonstrate superiority of Dato-DXd + durvalumab relative to ICC + pembrolizumab by assessment of PFS as assessed by BICR in participants with PD-L1 positive locally recurrent inoperable or metastatic TNBC. The study will be stratified based on geographic location (US/Canada/Europe vs. Dato-DXd monotherapy enrolling countries vs. rest of world), disease-free interval (DFI) history (de novo vs. prior DFI 6 to 12 months vs. prior DFI \> 12 months), and prior PD-1/PD-L1 treatment for early stage TNBC (yes vs. no). This study aims to see if Dato-DXd with durvalumab allows patients to live longer without their breast cancer getting worse, or simply to live longer, compared to patients receiving standard of care chemotherapy and pembrolizumab. This study is also looking to see how the treatment and the breast cancer affects patients' quality of life.