cathepsin-targeted fluorescent imaging probe VGT-309

A fluorescently quenched, cathepsin-activatable, near infrared (NIR) probe containing the dye indocyanine green (ICG), that may be used for cancer imaging purposes using an NIR imaging system. Upon administration, cathepsin-targeted fluorescent imaging probe VGT-309 covalently and irreversibly binds to cathepsins overexpressed by tumor cells. This displaces the quencher QC-1 and activates the ICG fluorophore. Upon NIR imaging, cathepsin-expressing tumor cells can be detected which allows for visualization of the tumor.