ERBB2 and breast cancer: In a phase III study TROPION-Breast01 (NCT05104866) (Study Details 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 ClinicalTrials.gov, 2023), the efficacy and safety of Dato-DXd are evaluated in patients with inoperable or metastatic HR+/HER2– breast cancer who have received one to two cycles of systemic chemotherapy.