Definition

A radioconjugate composed of an optimized affibody labeled with technetium Tc 99m, with potential use as a tracer for human epidermal growth factor receptor type 2 (HER2; ErbB2)-expressing tumors using single photon emission computed tomography (SPECT). Upon administration, the Tc 99m-labeled affibody ABH2 targets and binds to HER2-expressing tumor cells. This facilitates both detection of HER2-expressing tumor cells and assessment of responses to HER2-targeting chemotherapeutic agents using SPECT. HER2, a receptor tyrosine kinase, is mutated in many tumor cell types and plays a key role in tumor cell proliferation and tumor vascularization.