NCIt definition : A radioimmunoconjugate containing the recombinant humanized monoclonal antibody trastuzumab
labeled with the radioisotope zirconium Zr 89 with radioisotopic activity and potential
use as an imaging agent. The trastuzumab moiety of zirconium Zr 89 trastuzumab binds
with high affinity to the extracellular domain of human epidermal growth factor receptor
2 (HER2). Upon binding, the radioisotope moiety may be detected using positron emission
tomography (PET), thereby allowing the imaging and quantification of HER2-expressing
tumor cells. HER2, a tyrosine kinase client protein of heat shock protein 90 (Hsp90),
may be overexpressed on the cell surfaces of various tumor cell types.;