111In-ABY-025

**111In-ABY-025** is an investigational HER2-targeted SPECT/CT molecular-imaging radiotracer. It consists of the second-generation engineered Affibody protein ABY-025 radiolabeled with indium-111. The Affibody binds a high-affinity epitope in extracellular domain III of human epidermal growth factor receptor 2 that is distinct from the binding epitopes of trastuzumab and pertuzumab, enabling imaging during ongoing HER2-directed antibody treatment. It was developed by Affibody for noninvasive whole-body assessment of HER2 expression in metastatic breast cancer. In a first-in-human study, intravenous administration produced high-contrast images within 4 to 24 hours and differentiated biopsy-confirmed HER2-positive from HER2-negative metastatic lesions using serial uptake measurements. ([jnm.snmjournals.org](https://jnm.snmjournals.org/content/55/5/730))

Other names

[111In]In-ABY-025indium-111 ABY-025indium111 ABY-025indium 111 ABY-025