ERBB2 and neoplasm: Radio-iodinated 5F7GGC Nb with the residualizing agent N-succinimidyl 4-guanidinomethyl 3-125/131I-iodobenzoate (*I-SGMIB) not only presented a promising new conjugate for targeting HER2-expressing malignancies but also showed improved tumor retention and faster normal-tissue clearance than 131I-IB-Mal-D-GEEEK (63).