Molecular imaging of CXCR4 receptor expression in human cancer xenografts with [⁶⁴Cu]AMD3100 positron emission tomography

The chemokine receptor CXCR4 and its cognate ligand CXCL12 are pivotal for establishing metastases from many tumor types. Thus, CXCR4 may offer a cell surface target for molecular imaging of metastases, assisting diagnosis, staging, and therapeutic monitoring. Furthermore, noninvasive detection of CXCR4 status of a primary tumor may provide an index of the metastatic potential of the lesion. Here, we report the development and evaluation of [ ⁶⁴Cu]AMD3100, a positron-emitting analogue of the stem cell mobilizing agent plerixafor to image CXCR4 in human tumor xenografts preselected for graded expression of this receptor. This imaging method was evaluated in lung metastases derived from human MDA-MB-231 breast cancer cells. Ex vivo biodistribution studies, performed to validate the in vivo imaging data, confirmed the ability of [⁶⁴Cu] AMD3100 to image CXCR4 expression. Our findings show the feasibility of imaging CXCR4 by positron emission tomography using a clinically approved agent as a molecular scaffold.