American Association for Cancer Research
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Suppl Movie 1 from Cytotoxic T Lymphocyte Antigen-4 Blockade Enhances Antitumor Immunity by Stimulating Melanoma-Specific T-cell Motility

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posted on 2023-04-03, 22:42 authored by Tsvetelina Pentcheva-Hoang, Tyler R. Simpson, Welby Montalvo-Ortiz, James P. Allison

Pmel-1 dynamics in tumors prior to acute CTLA-4 blockade.



It is now clear that anti–CTLA-4 (α-CTLA-4) antibodies stimulate tumor immunity either by relieving inhibition of effector T-cell function or by depletion of regulatory T cells (Treg). Several recent reports, however, have suggested that these antibodies may deliver a “go” signal to effector T cells, thus interrupting T-cell receptor signaling and subsequent T-cell activation. We examined the behavior of melanoma-specific CD8+ pmel-1 T cells in the B16/BL6 mouse model using intravital microscopy. Pmel-1 velocities in progressively growing tumors were lower than their velocities in tumors given a therapeutic combination that included α-CTLA-4 antibodies, suggesting that successful immunotherapy correlates with greater T-cell motility. When α-CTLA-4 antibodies were injected during imaging, the velocities of pmel-1 T cells in tumor-draining lymph nodes also increased. Because α-CTLA-4 Fab fragments had the same effect as the intact antibody, the higher T-cell motility does not seem to be due to CTLA-4 inhibitory signaling but rather to the release of nonproductive stable interactions between tumor-infiltrating T cells and tumor targets or antigen-presenting cells subsequent to CTLA-4 blockade. This phenomenon resembles the recently described reversal of the antiviral T-cell motility paralysis by programmed death 1 (PD-1)–specific antibodies during T-cell exhaustion in persistent viral infections. Cancer Immunol Res; 2(10); 970–80. ©2014 AACR.