GPC3 and neoplasm: This enhanced tumor growth delay in animals treated with either amount of [225Ac]Ac–Macropa–GC33 compared to [225Ac]Ac–Macropa–IgG1 is supported by biodistribution data confirming the ability of [225Ac]Ac–Macropa–GC33 to preferentially target GPC3 in vivo in the HepG2 tumor model.