Affibody-mediated tumour targeting of HER-2 expressing xenografts in mice

Purpose Targeted delivery of radionuclides for diagnostic and therapeutic applications has until recently largely been limited to receptor ligands, antibodies and antibody-derived molecules. Here, we present a new type of molecule, a 15-kDa bivalent affibody called (ZHER2:4)2, with potential for such applications. The (ZHER2:4)2 affibody showed high apparent affinity (KD=3 nM) towards the oncogene product HER-2 (also called p185/neu or c-erbB-2), which is often overexpressed in breast and ovarian cancers. The purpose of this study was to investigate the in vivo properties of the new targeting agent.