ERBB2 and breast cancer: There have been a few previously reported preclinical studies of 225Ac-labeled trastuzumab for treatment of HER2-positive BC (Ballangrud et al. 2004; Borchardt et al. 2003; Yoshida et al. 2016), but none have reported the absorbed doses in HER2-positive SK-BR-3 BC cells or determined the relationship between dose and the SF in clonogenic survival assays, or measured DNA DSBs caused by emission of α-particles.