We previously reported the construction and characterization of[111In]In- and [225Ac]Ac-DOTA-trastuzumab IgGas potential theranostic pairs for HER2-positive BC.19 In our earlier report, we showed that [225Ac]Ac-DOTA-trastuzumabIgG was highly cytotoxic in vitro to HER2-positive SK-BR-3 human BCcells by inflicting multiple lethal DNA double-strand breaks. The gene discussed is ERBB2; the disease is breast cancer.