Definition

A radioconjugate composed of the scaffold protein DARPinG3, labeled with technetium Tc 99m, with potential imaging activity for human epidermal growth factor receptor 2 (HER2; EGFR2; ErbB2)-expressing tumor cells upon single photon emission computed tomography (SPECT)/computed tomography (CT). Upon administration of technetium Tc-99m DARPinG3, the DARPinG3 moiety targets and binds to HER2-expressing tumor cells. Upon SPECT/CT imaging, HER2-expressing tumor cells can be detected. HER2, a receptor tyrosine kinase, is mutated in many tumor cell types and plays a key role in tumor cell proliferation and tumor vascularization.