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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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 2

Treatment with IR and 9H10 alters the migratory behavior of TILs.

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Treatment with IR and 9H10 alters the migratory behavior of TILs. Cxcr6+...
Cxcr6+/gfp mice injected with 4T1-CFP cells and treated as described in Figure 1A were imaged on day 16. Movement of individual cells was tracked in the xy plane through stacks of 3D time-lapse images. Data are derived from 4 mice for each treatment. Each time lapse lasted 15 minutes and was acquired as a z-stack of 30 μm between 60 and 90 μm of depth below the capsule. (A) Trajectories of individual GFP+ TILs in CFP+ cell–rich areas (Supplemental Videos 3 and 4). The color scale shows time length of each path. Both IR and 9H10 as single treatment led to increased path lengths compared with controls. In contrast, when given in combination, IR+9H10 led to reduced migration of GFP+ TILs. Scale bar: 30 μm. Scatter plots of mean velocity (B), arrest coefficient (C), and confinement index (D) of GFP+ TILs in tumor cell–rich areas. The arrest coefficient was defined as the percentage of time a cell was moving at a speed less than 1.5 μm/min. Each data point represents a single cell, and red bars indicate mean values. *P < 0.05, **P < 0.005. (E) Random walk analysis. Mean displacement plotted as a function of the square root of time. The slope of each line represents the motility coefficient M and indicates the area an average cell scans per unit time. A liner curve indicates a random walk, a plateau indicates confinement, and a higher slope indicates directed motion.