gallium Ga-labeled PSMA-11-gadoxetate

A radioconjugate composed of a human prostate specific membrane antigen (PSMA)-targeting ligand, Glu-urea-Lys(Ahx) (Glu-NH-CO-NH-Lys(Ahx)) conjugated to both the paramagnetic contrast enhancer gadoxetate and the radioisotope gallium Ga 68, the latter is conjugated via an acyclic radiometal chelator N,N'-bis [2-hydroxy-5-(carboxyethyl)benzyl] ethylenediamine-N,N'-diacetic acid (HBED-CC), with potential use as a tracer for PSMA-expressing tumors during magnetic resonance imaging (MRI) and positron emission tomography (PET). Upon intravenous administration of the gallium Ga 68-labeled PSMA-11-gadoxetate, the Glu-urea-Lys(Ahx) moiety targets and binds to PSMA-expressing tumor cells. PSMA-expressing tumor cells can be detected during PET imaging and MRI. The dual imaging capabilities of this agent may improve both visualization of PSMA-expressing tumor cells and tumor assessment. PSMA, a tumor-associated antigen and type II transmembrane protein, is expressed on the membrane of prostatic epithelial cells and overexpressed on prostate tumor cells as well as on some other tumor cell types.