Other ADC agents, such as anti-HER2 trastuzumab deruxtecan, offer new options for HER-2-low and HER2-ultra-low breast cancer patients, a considerable proportion of whom have historically been categorized as HER-2 negative patients, including a subset of TNBC patients (Denkert et al., 2021). The gene discussed is ERBB2; the disease is breast cancer.