Abstract
Selective elimination of metastatic stem cells (MetSCs) promises to block metastatic dissemination. Colorectal cancer (CRC) cells overexpressing CXCR4 display trafficking functions and metastasis-initiating capacity. We assessed the antimetastatic activity of a nanoconjugate (T22-GFP-H6-FdU) that selectively delivers Floxuridine to CXCR4+ cells. In contrast to free oligo-FdU, intravenous T22-GFP-H6-FdU selectively accumulates and internalizes in CXCR4+ cancer cells, triggering DNA damage and apoptosis, which leads to their selective elimination and to reduced tumor re-initiation capacity. Repeated T22-GFP-H6-FdU administration in cell line and patient-derived CRC models blocks intravasation and completely prevents metastases development in 38-83% of mice, while showing CXCR4 expression-dependent and site-dependent reduction in foci number and size in liver, peritoneal, or lung metastases in the rest of mice, compared to free oligo-FdU. T22-GFP-H6-FdU induces also higher regression of established metastases than free oligo-FdU, with negligible distribution or toxicity in normal tissues. This targeted drug delivery approach yields potent antimetastatic effect, through selective depletion of metastatic CXCR4+ cancer cells, and validates metastatic stem cells (MetSCs) as targets for clinical therapy.