Firstly, biodistribution and retention of HER2-TTC was shown to be specific as evidenced by the high tumor uptake in both models (40–60% IA/g) compared to ca. 5% IA/g for the radiolabeled isotype control at 336 h, the latter due to antibody delivery from the enhanced permeability and retention effect [31]. The gene discussed is ERBB2; the disease is neoplasm.