title: Combined TIM-3 blockade and CD137 activation affords the long-term protection in a murine model of ovarian cancer.
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.
authors.affiliation: Department of Gynecology and Obstetrics, Shengjing Hospital, China Medical University, ShenYang 110004, China. zqg_cmu@163.com.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Guo
authors.forename: Dali
authors.initials: D
authors.lastname: Cheng
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Xia
authors.forename: Meng
authors.initials: M
authors.lastname: Luan
authors.forename: Liangliang
authors.initials: L
authors.lastname: Wu
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Shulan
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D016516:CD4-CD8 Ratio; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D000072597:Hepatitis A Virus Cellular Receptor 2; D051379:Mice; D008810:Mice, Inbred C57BL; D010051:Ovarian Neoplasms / Q000235:genetics / Q000276:immunology* / Q000473:pathology*; D010533:Peritoneal Lavage; D011991:Receptors, Virus / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D018417:Th1 Cells / Q000187:drug effects / Q000276:immunology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9 / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; C442241:Havcr2 protein, mouse; D000072597:Hepatitis A Virus Cellular Receptor 2; D011991:Receptors, Virus; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
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