also found that VHHs labelled with either [131I] or [225Ac] display a high and specific tumor uptake in HER2 positive brain metastasis lesions, whereas their counterparts mAbs Trastuzumab-[131I] and Trastuzumab-[225Ac] are unable to accumulate in intracranial tumors (26). Here, ERBB2 is linked to neoplasm.