ERBB2 and neoplasm: The radioimmunoconjugate [131I]SGMIB‐VHH‐1028 achieved a tumor‐to‐kidney therapeutic index of over 8.5 and almost completely inhibited tumor growth in BT474 xenograft‐bearing mice after doses of 18 and 30 MBq.[37] The same group also demonstrated the efficacy of HER2‐targeted radioimmunotherapy using a conjugated sdAb to a residualizing prosthetic group that was identical and labeled with the alpha‐emitting radio halogen 211At.[38]