GPC3 and neoplasm: Our choice of I-124 for labeling was justified based on two reasons: (1) concerns that using residualizing radiometals such as Zr-89 would result in higher liver background, as has been found with other radiometals (In-111 and Lu-177), thus lowering tumor-to-normal liver contrast, and (2) the slow internalization rate of GPC3 when targeted by a radiolabeled antibody [17, 18].