ERBB2 and breast cancer: This came from the results of the 2022 DESTINY-Breast04 trial, which prompted the United States Food and Drug Administration (FDA) to expand the approval of the HER2 antibody–drug conjugate, trastuzumab-deruxtecan, from metastatic breast cancer patients with HER2 protein overexpression/amplification to also include metastatic patients with HER2 IHC 1+ or 2+/ISH negative results.