Development of an oncolytic HSV vector fully retargeted specifically to cellular EpCAM for virus entry and cell-to-cell spread

Gene Ther. 2016 Jun;23(6):479-88. doi: 10.1038/gt.2016.17. Epub 2016 Feb 23.

Abstract

Oncolytic herpes simplex virus (HSV) vectors have attracted increasing attention as novel anti-cancer agents. HSV entry is triggered by the binding of glycoprotein D (gD) to its receptors, such as herpesvirus entry mediator or nectin-1. We have recently reported the construction of a fully retargeted HSV platform that incorporates single-chain antibodies (scFv) into gD to mediate entry exclusively via tumor-associated antigens. In this study, we created an scFv directed against epithelial cell adhesion molecule (EpCAM), a recognized carcinoma-associated antigen, and inserted it into the retargeted HSV platform that is ablated for gD recognition of its canonical receptors and contains the entry-enhancing mutations in gB we previously identified. We observed that both initial entry and subsequent cell-to-cell spread of the retargeted virus were stringently dependent on cellular EpCAM expression. Interestingly, the retargeted virus developed larger plaques on some of the human tumor lines tested than the control virus bearing wild-type gD. Intratumoral injection of the retargeted virus revealed antitumor activity in a mouse xenograft model. These observations illustrate the versatility of our retargeted HSV platform as it allows expansion of the oncolytic virus toolbox for the treatment of diverse cancers.

MeSH terms

  • Animals
  • CHO Cells
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism
  • Cell Line, Tumor
  • Chlorocebus aethiops / immunology
  • Cricetulus
  • Epithelial Cell Adhesion Molecule / genetics*
  • Epithelial Cell Adhesion Molecule / immunology
  • Female
  • Genetic Vectors / genetics*
  • Genetic Vectors / metabolism
  • Hep G2 Cells
  • Herpesvirus 1, Human / genetics*
  • Herpesvirus 1, Human / metabolism
  • Humans
  • Mice
  • Nectins
  • Neoplasms / therapy*
  • Neoplasms / virology*
  • Oncolytic Virotherapy / methods*
  • Random Allocation
  • Receptors, Virus / metabolism
  • Single-Chain Antibodies / genetics
  • Single-Chain Antibodies / immunology
  • Transfection / methods
  • Vero Cells
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism
  • Virus Internalization
  • Xenograft Model Antitumor Assays

Substances

  • Cell Adhesion Molecules
  • EPCAM protein, human
  • Epithelial Cell Adhesion Molecule
  • NECTIN1 protein, human
  • Nectin1 protein, mouse
  • Nectins
  • Receptors, Virus
  • Single-Chain Antibodies
  • Viral Envelope Proteins
  • glycoprotein D, Human herpesvirus 1