Synergistic enhancement of CD8+ T cell-mediated tumor vaccine efficacy by an anti-transforming growth factor-beta monoclonal antibody

Clin Cancer Res. 2009 Nov 1;15(21):6560-9. doi: 10.1158/1078-0432.CCR-09-1066. Epub 2009 Oct 27.

Abstract

Purpose: Transforming growth factor-beta (TGF-beta) is an immunosuppressive cytokine, having direct suppressive activity against conventional CD4(+) and CD8(+)T cells and natural killer cells, thereby inhibiting tumor immunosurveillance. Here, we investigated possible synergy between anti-TGF-beta (1D11) and a peptide vaccine on induction of antitumor immunity, and the mechanisms accounting for synergistic efficacy.

Experimental design: The effect of combination treatment with a peptide vaccine and anti-TGF-beta was examined in a subcutaneous TC1 tumor model, as well as the mechanisms of protection induced by this treatment.

Results: Anti-TGF-beta significantly and synergistically improved vaccine efficacy as measured by reduction in primary tumor growth, although anti-TGF-beta alone had no impact. The number of tumor antigen-specific CTL with high functional avidity as measured by IFN-gamma production and lytic activity was significantly increased in vaccinated mice by TGF-beta neutralization. Although TGF-beta is known to play a critical role in CD4(+)Foxp3(+) Treg cells, Treg depletion/suppression by an anti-CD25 monoclonal antibody (PC61) before tumor challenge did not enhance vaccine efficacy, and adding anti-TGF-beta did not affect Treg numbers in lymph nodes or tumors or their function. Also, TGF-beta neutralization had no effect on interleukin-17-producing T cells, which are induced by TGF-beta and interleukin-6. Absence of type II NKT cells, which induce myeloid cells to produce TGF-beta, was not sufficient to eliminate all sources of suppressive TGF-beta. Finally, the synergistic protection induced by anti-TGF-beta vaccine augmentation was mediated by CD8(+) T cells since anti-CD8 treatment completely abrogated the effect.

Conclusions: These results suggest that TGF-beta blockade may be useful for enhancing cancer vaccine efficacy.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Antibodies, Monoclonal / therapeutic use*
  • CD8-Positive T-Lymphocytes / immunology*
  • Cancer Vaccines / therapeutic use*
  • Cell Line, Tumor
  • Immunosuppression
  • Mice
  • Mice, Inbred C57BL
  • T-Lymphocytes, Cytotoxic / immunology*
  • Transforming Growth Factor beta / immunology*
  • Vaccines, Subunit / therapeutic use*

Substances

  • Antibodies, Monoclonal
  • Cancer Vaccines
  • Transforming Growth Factor beta
  • Vaccines, Subunit