ERBB3 and breast cancer: The main ongoing clinical trials to evaluate this drug are NCT04610528 [A Window-of-opportunity Study of U3-1402, a HER3-targeting Antibody-drug Conjugate in Operable Breast Cancer According to ERBB3 Expression (TOT-HER3)]; NCT02980341 (Phase I/II Study of U3-1402 in Subjects With Human Epidermal Growth Factor Receptor 3 (HER3) Positive Metastatic Breast Cancer); NCT04965766 [Patritumab Deruxtecan (U3-1402) in Unresectable Locally Advanced or Metastatic Breast Cancer (ICARUS-BREAST)]; and NCT04699630 (A Study of U3-1402 in Subjects With Metastatic Breast Cancer).