Ligation of the TNF receptor family costimulatory molecule OX40 (CD134) with an agonist anti-OX40 monoclonal antibody (mAb) enhances antitumor immunity by augmenting T-cell differentiation as well as turning off the suppressive activity of the FoxP3+CD4+ regulatory T cells (Treg). In addition, antibody-mediated blockade of the checkpoint inhibitor CTLA-4 releases the “brakes” on T cells to augment tumor immunotherapy. However, monotherapy with these agents has limited therapeutic benefit particularly against poorly immunogenic murine tumors. Therefore, we examined whether the administration of agonist anti-OX40 therapy in the presence of CTLA-4 blockade would enhance tumor immunotherapy. Combined anti-OX40/anti-CTLA-4 immunotherapy significantly enhanced tumor regression and the survival of tumor-bearing hosts in a CD4 and CD8 T cell–dependent manner. Mechanistic studies revealed that the combination immunotherapy directed the expansion of effector T-bethigh/Eomeshigh granzyme B+ CD8 T cells. Dual immunotherapy also induced distinct populations of Th1 [interleukin (IL)-2, IFN-γ], and, surprisingly, Th2 (IL-4, IL-5, and IL-13) CD4 T cells exhibiting increased T-bet and Gata-3 expression. Furthermore, IL-4 blockade inhibited the Th2 response, while maintaining the Th1 CD4 and effector CD8 T cells that enhanced tumor-free survival. These data demonstrate that refining the global T-cell response during combination immunotherapy can further enhance the therapeutic efficacy of these agents. Cancer Immunol Res; 2(2); 1–12. ©2013 AACR.
Note: Supplementary data for this article are available at Cancer Immunology Research Online (http://cancerimmunolres.aacrjournals.org/).
- Received March 27, 2013.
- Revision received October 14, 2013.
- Accepted October 30, 2013.
- ©2013 American Association for Cancer Research.