ERBB2 and breast cancer: SG was approved by the FDA on February 2023 for patients with unresectable, locally advanced or metastatic hormone receptor (HR)-positive, HER2-negative (IHC 0, IHC 1+, or IHC 2+ with ISH−]) breast cancer who have received endocrine-based therapy and at least two additional systemic therapies in the metastatic setting.