Combination of a T cell activating therapy and anti-phosphatidylserine enhances anti-tumour immune responses in a HPV16 E7-expressing C3 tumour model

Sci Rep. 2021 Feb 24;11(1):4502. doi: 10.1038/s41598-021-82108-4.

Abstract

DPX is a novel delivery platform that generates targeted CD8 + T cells and drives antigen-specific cytotoxic T cells into tumours. Cancer cells upregulate phosphatidylserine (PS) on the cell surface as a mechanism to induce an immunosuppressive microenvironment. Development of anti-PS targeting antibodies have highlighted the ability of a PS-blockade to enhance tumour control by T cells by releasing immunosuppression. Here, C57BL/6 mice were implanted with HPV16 E7 target-expressing C3 tumours and subjected to low dose intermittent cyclophosphamide (CPA) in combination with DPX-R9F treatment targeting an E7 antigen with and without anti-PS and/or anti-PD-1 targeting antibodies. Immune responses were assessed via IFN-γ ELISPOT assay and the tumour microenvironment was further analyzed using RT-qPCR. We show that the combination of DPX-R9F and PS-targeting antibodies with and without anti-PD-1 demonstrated increased efficacy compared to untreated controls. All treatments containing DPX-R9F led to T cell activation as assessed by IFN-γ ELISPOT. Furthermore, DPX-R9F/anti-PS treatment significantly elevated cytotoxic T cells, macrophages and dendritic cells based on RT-qPCR analysis. Overall, our data indicates that anti-tumour responses are driven through a variety of immune cells within this model and highlights the need to investigate combination therapies which increase tumour immune infiltration, such as anti-phosphotidylserine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD8-Positive T-Lymphocytes / immunology*
  • Cell Line, Tumor
  • Disease Models, Animal
  • Female
  • Immunity / immunology*
  • Immunotherapy / methods
  • Mice
  • Mice, Inbred C57BL
  • Papillomavirus E7 Proteins / immunology*
  • Phosphatidylserines / immunology*
  • Programmed Cell Death 1 Receptor / immunology
  • T-Lymphocytes, Cytotoxic / immunology*
  • Tumor Microenvironment / immunology

Substances

  • Papillomavirus E7 Proteins
  • Phosphatidylserines
  • Programmed Cell Death 1 Receptor
  • oncogene protein E7, Human papillomavirus type 16