Potentiating Oncolytic Virus-Induced Immune-Mediated Tumor Cell Killing Using Histone Deacetylase Inhibition

Mol Ther. 2019 Jun 5;27(6):1139-1152. doi: 10.1016/j.ymthe.2019.04.008. Epub 2019 Apr 14.

Abstract

A clinical oncolytic herpes simplex virus (HSV) encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), talimogene laherparepvec, causes regression of injected and non-injected melanoma lesions in patients and is now licensed for clinical use in advanced melanoma. To date, limited data are available regarding the mechanisms of human anti-tumor immune priming, an improved understanding of which could inform the development of future combination strategies with improved efficacy. This study addressed direct oncolysis and innate and adaptive human immune-mediated effects of a closely related HSV encoding GM-CSF (HSVGM-CSF) alone and in combination with histone deacetylase inhibition. We found that HSVGM-CSF supported activation of anti-melanoma immunity via monocyte-mediated type I interferon production, which activates NK cells, and viral maturation of immature dendritic cells (iDCs) into potent antigen-presenting cells for cytotoxic T lymphocyte (CTL) priming. Addition of the histone deacetylase inhibitor valproic acid (VPA) to HSVGM-CSF treatment of tumor cells increased viral replication, viral GM-CSF production, and oncolysis and augmented the development of anti-tumor immunity. Mechanistically, VPA increased expression of activating ligands for NK cell recognition and induced expression of tumor-associated antigens, supporting innate NK cell killing and CTL priming. These data support the clinical combination of talimogene laherparepvec with histone deacetylase inhibition to enhance oncolysis and anti-tumor immunity.

Keywords: HSV,cancer immunotherapy; VPA; herpes simplex virus; histone deacetylase inhibitor; oncolytic virus; valproic acid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Neoplasm / drug effects
  • Antigens, Neoplasm / metabolism
  • Antineoplastic Agents, Immunological / therapeutic use
  • Biological Products / therapeutic use
  • Cell Survival / genetics
  • Dendritic Cells / immunology
  • Drug Therapy, Combination
  • Genetic Vectors
  • Granulocyte-Macrophage Colony-Stimulating Factor / genetics
  • Herpesvirus 1, Human
  • Histone Deacetylase Inhibitors / therapeutic use*
  • Humans
  • Interferon Type I / metabolism
  • Killer Cells, Natural / immunology
  • MCF-7 Cells
  • Melanoma / pathology
  • Melanoma / therapy*
  • Oncolytic Virotherapy / methods*
  • Oncolytic Viruses / genetics
  • Oncolytic Viruses / metabolism*
  • Simplexvirus / genetics
  • Simplexvirus / immunology*
  • Skin Neoplasms / pathology
  • Skin Neoplasms / therapy*
  • T-Lymphocytes, Cytotoxic / immunology
  • Valproic Acid / therapeutic use*

Substances

  • Antigens, Neoplasm
  • Antineoplastic Agents, Immunological
  • Biological Products
  • CSF2 protein, human
  • Histone Deacetylase Inhibitors
  • Interferon Type I
  • talimogene laherparepvec
  • Valproic Acid
  • Granulocyte-Macrophage Colony-Stimulating Factor