[99mTc]Tc-CEEG-rL-A9

[99mTc]Tc-CEEG-rL-A9 is a technetium-99m labeled radiopeptide designed for the diagnostic imaging of HER2-positive breast cancer. It comprises the HER2-targeting peptide rL-A9 conjugated to a Cys-Glu-Glu-Gly (CEEG) peptide-based chelator. During preclinical development, the [99mTc]Tc-CEEG-rL-A9 variant demonstrated poor chemical stability and rapid decomposition, which led to the cessation of its development in favor of more stable analogs like the CGGG-conjugated variant. Its intended mechanism of action was to selectively bind to the Human Epidermal Growth Factor Receptor 2 (HER2) on tumor cells, allowing for their detection via gamma scintigraphy or SPECT imaging.