ICOS costimulation in combination with CTLA-4 blockade remodels tumor-associated macrophages toward an antitumor phenotype

J Exp Med. 2024 Apr 1;221(4):e20231263. doi: 10.1084/jem.20231263. Epub 2024 Mar 22.

Abstract

We have previously demonstrated synergy between ICOS costimulation (IVAX; ICOSL-transduced B16-F10 cellular vaccine) and CTLA-4 blockade in antitumor therapy. In this study, we employed CyTOF and single-cell RNA sequencing and observed significant remodeling of the lymphoid and myeloid compartments in combination therapy. Compared with anti-CTLA-4 monotherapy, the combination therapy enriched Th1 CD4 T cells, effector CD8 T cells, and M1-like antitumor proinflammatory macrophages. These macrophages were critical to the therapeutic efficacy of anti-CTLA-4 combined with IVAX or anti-PD-1. Macrophage depletion with clodronate reduced the tumor-infiltrating effector CD4 and CD8 T cells, impairing their antitumor functions. Furthermore, the recruitment and polarization of M1-like macrophages required IFN-γ. Therefore, in this study, we show that there is a positive feedback loop between intratumoral effector T cells and tumor-associated macrophages (TAMs), in which the IFN-γ produced by the T cells polarizes the TAMs into M1-like phenotype, and the TAMs, in turn, reshape the tumor microenvironment to facilitate T cell infiltration, immune function, and tumor rejection.

MeSH terms

  • CD8-Positive T-Lymphocytes
  • CTLA-4 Antigen
  • Humans
  • Inducible T-Cell Co-Stimulator Protein
  • Neoplasms* / therapy
  • Phenotype
  • Tumor Microenvironment
  • Tumor-Associated Macrophages*

Substances

  • CTLA-4 Antigen
  • ICOS protein, human
  • Inducible T-Cell Co-Stimulator Protein