Targeted adenovirus gene transfer to endothelial and smooth muscle cells by using bispecific antibodies

Abstract

A major hurdle to adenovirus (Ad)-mediated gene transfer is that the target tissue lacks sufficient levels of receptors to mediate vector attachment via its fiber coat protein. Endothelial and smooth muscle cells are primary targets in gene therapy approaches to prevent restenosis following angioplasty or to promote or inhibit angiogenesis. However, Ad poorly binds and transduces these cells because of their low or undetectable levels of functional Ad fiber receptor. The Ad-binding deficiency of these cells was overcome by targeting Ad binding to ␣ v integrin receptors that are sufficiently expressed by these cells. In order to target ␣ v integrins, a bispecific antibody (bsAb) that comprised a monoclonal Ab to the FLAG peptide epitope, DYKDDDDK, and a monoclonal Ab to ␣ v integrins was constructed. In conjunction with the bsAb, a new vector, AdFLAG, which incorporated the FLAG peptide epitope into its penton base protein was constructed. Complexing AdFLAG with the bsAb increased the ␤-glucuronidase transduction of human venule endothelial cells and human intestinal smooth muscle cells by seven-to ninefold compared with transduction by AdFLAG alone. The increased transduction efficiency was shown to occur through the specific interaction of the complex with ␣ v integrins. These results demonstrate that bsAbs can be successfully used to target Ad to a specific cellular receptor and thereby increase the efficiency of gene transfer.

Recent advances in genetic modification of adenovirus vectors for cancer treatment

“…(4,5) The next step, internalization of the virus, is promoted by an interaction between the arginine-glycine-aspartic acid (RGD) sequence of the penton base and av integrins on the cell surface. (13,14) Transductional targeting aims to affect the cellular entry of vectors. This type of targeting can create tissue tropism to new cellular targets by conferring novel ligand-mediated binding properties to receptors and by simultaneously inhibiting binding to natural receptors (detargeting).…”

Strategies to overcome host immunity to adenovirus vectors in vaccine development

“…Alternative strategies for shielding Ad from PEI include the utilization of bispecific adapters that bind to Ad capsid proteins and change the cell-specificity of Ad transduction. Bispecific adapters were originally developed as a means to block CAR-mediated transduction and retarget Ad to unique cell surface receptors [183][184][185]. One bispecific adapter that has shown promise for mediating the transduction of normally refractory DCs consists of the soluble domain of CAR fused to the ectodomain of CD40L [186][187][188].…”

Targeted Adenoviral Vectors I

“…To construct bsAb adapters, Wickham et al used monoclonal antibody (mAb) against an FLAG peptide, which was genetically incorporated in place of the deleted RGD sequence in penton base protein, chemically conjugated to mAb with specificities for α v -integrin receptors or human CD3 to redirect the AdFLAG vector to endothelial and smooth muscle cells or T cells, respectively. 18,19 Although successfully demonstrating the feasibility of in vitro virus retargeting via non-Ad receptors displayed on human venule endothelial cells, intestinal smooth muscle cells, and resting T cells that are normally refractory, this approach was later abandoned, apparently because of reduced virus viability resulting from RGD sequence deletion. 20 An alternative approach to provide adapter binding to Ad capsid was proposed by Douglas et al, 21 based on the use of neutralizing mAb 1D6.14, which blocks binding of the Ad5 fiber knob to CAR.…”