Suppressing T cell motility induced by anti–CTLA-4 monotherapy improves antitumor effects
Maria Grazia Ruocco, … , Michael L. Dustin, Sandra Demaria
Maria Grazia Ruocco, … , Michael L. Dustin, Sandra Demaria
Published September 4, 2012
Citation Information: J Clin Invest. 2012;122(10):3718-3730. https://doi.org/10.1172/JCI61931.
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Research Article Oncology

Suppressing T cell motility induced by anti–CTLA-4 monotherapy improves antitumor effects

Abstract

A promising strategy for cancer immunotherapy is to disrupt key pathways regulating immune tolerance, such as cytotoxic T lymphocyte–associated protein 4 (CTLA-4). However, the determinants of response to anti–CTLA-4 mAb treatment remain incompletely understood. In murine models, anti–CTLA-4 mAbs alone fail to induce effective immune responses to poorly immunogenic tumors but are successful when combined with additional interventions, including local ionizing radiation (IR) therapy. We employed an established model based on control of a mouse carcinoma cell line to study endogenous tumor-infiltrating CD8+ T lymphocytes (TILs) following treatment with the anti–CTLA-4 mAb 9H10. Alone, 9H10 monotherapy reversed the arrest of TILs with carcinoma cells in vivo. In contrast, the combination of 9H10 and IR restored MHC class I–dependent arrest. After implantation, the carcinoma cells had reduced expression of retinoic acid early inducible–1 (RAE-1), a ligand for natural killer cell group 2D (NKG2D) receptor. We found that RAE-1 expression was induced by IR in vivo and that anti-NKG2D mAb blocked the TIL arrest induced by IR/9H10 combination therapy. These results demonstrate that anti–CTLA-4 mAb therapy induces motility of TIL and that NKG2D ligation offsets this effect to enhance TILs arrest and antitumor activity.

Authors

Maria Grazia Ruocco, Karsten A. Pilones, Noriko Kawashima, Michael Cammer, Julie Huang, James S. Babb, Mengling Liu, Silvia C. Formenti, Michael L. Dustin, Sandra Demaria

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Figure 1

Characterization of 4T1-CFP tumor model for imaging CD8+ TILs in Cxcr6+/gfp mice treated with local radiotherapy and anti–CTLA-4 mAb.

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Characterization of 4T1-CFP tumor model for imaging CD8+ TILs in Cxcr6+/...
(A) Treatment schedule. (B) Growth of 4T1-CFP tumors of untreated and IR+9H10-treated mice (n = 6/group). Treated mice showed significant tumor inhibition (P = 0.0006). Vertical dashed lines indicate the days at which in vivo TPLSM was performed. (C–E) Ex vivo characterization of CD8 TILs on day 21. Samples were gated on CD8+ T cells. (C) Most GFP+ TILs express CD69, and represent a greater proportion of CD8+ cells in tumors treated with IR+9H10 than controls. (D) IR+9H10 treatment increases the density of CD8+ TILs about 1.8-fold, but the density of CD8 GFP+ TILs is increased by more than 4-fold. (E) The majority CD8+ TILs producing IFN-γ are GFP+, as determined by intracellular staining. Error bars are absent because pooling of tumors within each group was necessary to obtain sufficient number of cells for analysis. Results are from 10 mice/group and are representative of 2 experiments. (F) In vivo TPLSM images of GFP+ TILs in 4T1-CFP tumors on day 22 (Supplemental Videos 1 and 2). Mice were mock treated (Control) or treated as indicated. Images are representative of 6–8 independent experiments for each treatment. Scale bars: 58 μm. T cells are green (GFP), 4T1 cells are blue (CFP), blood vessels are red (quantum dots). (G) Quantification of GFP+ TILs on day 22. Results are the mean ± SD of 9 fields (9 × 104 μm2) from 3 mice per group. *P < 0.05, **P < 0.005.