Selective depletion of metastatic stem cells as therapy for human colorectal cancer

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.

Efficient bioactive oligonucleotide‐protein conjugation for cell‐targeted cancer therapy

“…To this end, we have selected the functionalization of T22‐GFP‐H6 protein with oligonucleotides carrying several units of FdU using the method based on the thiol‐maleimide reaction. We have demonstrated that this conjugate showed antitumor but specifically antimetastatic activity in a CXCR4+ metastatic colorectal cancer model …”

“…It is worth to mention that in the case of BSA in spite of being a bigger protein than T22‐GFP‐H6 the DLS data indicate a smaller size (7.4 nm) compared with T22‐GFP‐H6. This is because T22‐GFP‐H6 self‐assemble to produce a larger protein nanoparticle ,…”

“…Similarly, using the same conditions, in the inverted one‐pot addition, we obtained 5.9 FdU oligonucleotide units that was the highest ratio of oligo‐FdU coupled to the nanoparticle protein. T22‐GFP‐H6‐FdU conjugates were used for blocking CXCR4+metastatic colon cancer stem‐cells . Using these conditions, concentrated conjugates were obtained that were highly recommended for clinical testing as we reduced the volume required for intravenous administration.…”

An Auristatin nanoconjugate targeting CXCR4+ leukemic cells blocks acute myeloid leukemia dissemination

“…Here, we specifically tested if a novel T22-GFP-H6-Auristatin nanoconjugate (NC) selectively eliminates CXCR4+ AML cells, and therefore LSCs, in an AML disseminated model, to improve chemotherapy performance, which reduces the differentiated tumor bulk but does not eliminate LSCs [20]. The NC incorporates a protein nanoparticle to selectively internalize in CXCR4+ AML cells by exploiting high CXCR4 overexpression in LSCs as compared to HSCs [6,20], similarly to a previous approach in colorectal cancer (CRC) [21,22]. The NC is loaded with Auristatin E, a microtubuledestabilizing toxin, introduced in clinical oncohematology [23,24].…”

Engineering Secretory Amyloids for Remote and Highly Selective Destruction of Metastatic Foci

“…In this context, and to explore in detail the potential systemic use of IBs as a novel drug‐releasing material, we administered T22‐PE24‐H6 IBs to metastatic mouse models derived from human colorectal and based on CXCR4 + SW1417‐luciferase expressing cells . Note that as previous reference, we had determined the biodistribution of a fluorescent protein material released from IBs formed by T22‐empowered GFP, which followed the expected biodistribution and tumor accumulation .…”