ERBB2 and breast cancer: In September 2023, the EMA granted approval for the use of T-Dxd as a monotherapy in adult patients with unresectable or metastatic HER2-positive breast cancer, who have received one or more prior anti-HER2-based regimens, and also for the treatment of adult patients with unresectable or metastatic HER2-low breast cancer, who have received prior chemotherapy in the metastatic setting or developed disease recurrence during or within 6 months of completing adjuvant chemotherapy.