Combined TIM-3 blockade and CD137 activation affords the long-term protection in a murine model of ovarian cancer

J Transl Med. 2013 Sep 17;11:215. doi: 10.1186/1479-5876-11-215.

Abstract

Background: T-cell immunoglobulin and mucin domain 3 (TIM-3) is known as a negative immune regulator and emerging data have implicated TIM-3 a pivotal role in suppressing antitumor immunity. The co-stimulatory receptor CD137 is transiently upregulated on T-cells following activation and increases their proliferation and survival when engaged. Although antagonistic anti-TIM-3 or agonistic anti-CD137 antibodies can promote the rejection of several murine tumors, some poorly immunogenic tumors were refractory to this treatment. In this study, we sought to evaluate whether combined TIM-3 blockade and CD137 activation would significantly improve the immunotherapy in the murine ID8 ovarian cancer model.

Methods: Mice with established ID8 tumor were intraperitoneally injected with single or combined anti-TIM-3/CD137 monoclonal antibody (mAb); mice survival was recorded, the composition and gene expression of tumor-infiltrating immune cells in these mice was analyzed by flow cytometry and quantitative RT-PCR respectively, and the function of CD8⁺ cells was evaluated by ELISA and cytotoxicity assay.

Results: Either anti-TIM-3 or CD137 mAb alone, although effective in 3 days established tumor, was unable to prevent tumor progression in mice bearing 10 days established tumor, however, combined anti-TIM-3/CD137 mAb significantly inhibited the growth of these tumors with 60% of mice tumor free 90 days after tumor inoculation. Therapeutic efficacy was associated with a systemic immune response with memory and antigen specificity, required CD4⁺ cells and CD8⁺ cells. The 2 mAb combination increased CD4⁺ and CD8⁺ cells and decreased immunosuppressive CD4⁺FoxP3⁺ regulatory T (Treg) cells and CD11b⁺Gr-1⁺ myeloid suppressor cells (MDSC) at tumor sites, giving rise to significantly elevated ratios of CD4⁺ and CD8⁺ cells to Treg and MDSC; This is consistent with biasing local immune response towards an immunostimulatory Th1 type and is further supported by quantitative RT-PCR data showing the increased Th1-associated genes by anti-TIM-3/CD137 treatment. The increased CD8⁺ T cells produced high level of IFN-γ upon tumor antigen stimulation and displayed antigen-specific cytotoxic activity.

Conclusions: To our knowledge, this is the first report investigating the effects of anti-TIM-3/CD137 combined mAb in a murine ovarian cancer model, and our results may aid the design of future trials for ovarian cancer immunotherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • CD4-CD8 Ratio
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / immunology
  • Disease Models, Animal
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Hepatitis A Virus Cellular Receptor 2
  • Mice
  • Mice, Inbred C57BL
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / immunology*
  • Ovarian Neoplasms / pathology*
  • Peritoneal Lavage
  • Receptors, Virus / antagonists & inhibitors*
  • Receptors, Virus / metabolism
  • T-Lymphocytes, Cytotoxic / immunology
  • Th1 Cells / drug effects
  • Th1 Cells / immunology
  • Tumor Necrosis Factor Receptor Superfamily, Member 9 / metabolism*

Substances

  • Antibodies, Monoclonal
  • Havcr2 protein, mouse
  • Hepatitis A Virus Cellular Receptor 2
  • Receptors, Virus
  • Tumor Necrosis Factor Receptor Superfamily, Member 9