More recently, by using very small HER2-functionalized silica nanoparticles (~7 nm), tumor targeting efficiencies of 10.3–17.2% ID/g were achieved in murine xenografts of HER2-positive BT-474 tumors, compared to 3.3–6.1% ID/g for HER2-negative tumors or untargeted particles (Chen et al., 2018). Here, ERBB2 is linked to neoplasm.