CXCL12 retargeting of an adenovirus vector to cancer cells using a bispecific adapter

Abstract

Ad vectors are promising delivery vehicles for cancer therapeutic interventions. However, their application is limited by promiscuous tissue tropism and hepatotoxicity. This limitation can be avoided by altering the native tropism of Ads so that they can be redirected to the target cells through alternate cellular receptors. The CXCR4 chemokine receptor belongs to a large superfamily of G-protein-coupled receptors and is known to be upregulated in a wide variety of cancers, including breast cancer and melanoma. These receptors have been associated with cancer cell survival, progression, and metastasis. In the current study, an Ad to cancer cells overexpressing CXCR4 by using a bispecific adapter, sCAR-CXCL12, was retargeted. The sCAR-CXCL12 adapter contained the soluble ectodomain form of the native Ad5 receptor (sCAR), which was fused to a mature human chemokine ligand, CXCL12, through a short peptide linker. A dramatic increase in the infectivity of cancer cells using a targeted Ad vector compared with an untargeted vector was observed. Furthermore, sCAR-CXCL12 attenuated Ad infection of liver ex vivo and in vivo and enhanced Ad vector infection of xenograft tumors implanted in immunodeficient SCID-bg mice. Thus, the sCAR-CXCL12 adapter could be used to retarget Ad vectors to chemokine receptor-positive tumors.

The Effect of Hypoxia on the Expression of CXC Chemokines and CXC Chemokine Receptors—A Review of Literature

“…An anti-CXCR4 antibody, or peptides recognizing CXCR4, have also been tested to target cytotoxic substances against cancer stem cells in acute myelogenous leukemia [ 326 ], breast cancer cells [ 327 ], colorectal cancer cells [ 328 ] and multiple myeloma [ 329 ]. This method can also be used to retarget an adenovirus vector against a tumor cell in gene therapy [ 330 ].…”

Oncolytic Adenoviruses: Strategies for Improved Targeting and Specificity

“…By using a soluble form of the same natural receptor, they could block (saturate) the native viral protein, leading to effective detargeting. This was demonstrated by using a soluble CAR (sCAR) conjugated to several ligands and ScFvs to retarget AdVs [136][137][138][139][140][141][142][143][144]. Hexon-Coagulation Factor (F)X (FX) binding was utilized in a similar manner by conjugating an ScFv against HER2/neu to the FX protein [145].…”

“…Antibody-antibody-based bridging molecules Anti-AdV protein conjugated to VEGFR, TIE-2, integrins, EPCAM, EGFR, HER2, Endoglin, HMWMAA [127][128][129][130][131][132] Antibody-ligand-based bridging molecules anti-AdV protein conjugated to Folate, TNFa, IGF1, EGF [133,134] Peptide-antibody-based bridging molecules p75 neurotropin receptor on hepatic stellate cells [135] Soluble receptors conjugated to ligands (sCAR, FX) EGF, anti-Cd40 ScFv, ApoE ligand, anti-ErbB2, anti-CEA, Polysialyc-acid (PSA), CXCL12 [136][137][138][139][140][141][142][143][144][145] BiTE, Leucine-zipper-based linkers CD44v6, anti-B-cell maturation antigen, FR-α, EGFR, EpCAM, carcinoembryonic antigen, CD40 [147][148][149][150][151][152][153][154] b. Selective Expression of Effectors (Inhibitors/Enhancers) in Specific Cells.…”

Nonreplicating Adenoviral Vectors: Improving Tropism and Delivery of Cancer Gene Therapy

“…A viable alternative may be the use of adapter molecules. Bhatia et al [ 179 ] developed an anti-CXCR4 bispecific adapter (sCAR-CXCL12). Chemokine receptor type 4 (CXCR4) is known to be overexpressed in a wide variety of cancers, such as melanoma [ 180 ] and breast cancer [ 181 ], and it is associated with metastasis and poor overall survival.…”

“…Chemokine receptor type 4 (CXCR4) is known to be overexpressed in a wide variety of cancers, such as melanoma [ 180 ] and breast cancer [ 181 ], and it is associated with metastasis and poor overall survival. Bhatia et al [ 179 ] designed a recombinant adapter molecule composed of an ectodomain portion of the human CAR, followed by a 5-peptide linker (GGPGS) and a 6-His tag sequence, fused to the mature human chemokine CXCL12/SDF-1a sequence (CXCR4 ligand). According to the researchers, this bispecific adapter attenuated liver infection in vivo and a promoted a considerable increase in cancer cell infection, as observed in xenograft tumors in mice.…”