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Local Depletion of Immune Checkpoint Ligand CTLA4 Expressing Cells in Tumor Beds Enhances Antitumor Host Immunity.

ABSTRACT: Near-infrared photoimmunotherapy (NIR-PIT) is a cancer treatment that utilizes antibody-photoabsorber (IR700) conjugates to selectively kill target cells by exposing them to NIR light. Cytotoxic T-lymphocyte antigen 4 (CTLA4) is a major immune checkpoint ligand mediating antitumor immune suppression. Local depletion of CTLA4 expressing cells in the tumor bed with NIR-PIT could enhance antitumor immune responses by both blocking the CTLA4-axis and depleting immune suppressive cells. The aim of this study is to evaluate the antitumor efficacy of CTLA4-targeted NIR-PIT using four murine tumor models, MC38-luc, LL/2-luc, MOC2-luc, and MOC2. The CTLA4-targeted NIR-PIT depletes intratumoral CTLA4 expressing cells which are mostly regulatory T cells. In vivo CTLA4-targeted NIR-PIT yields complete responses in 80% of MC38-luc, 70% of LL/2-luc and 40% of MOC2-luc tumors prolonging survival in all cases. After CTLA4-targeted NIR-PIT, activation and infiltration of CD8+ T cells within the tumor microenvironment is observed. In conclusion, CTLA4-targeted NIR-PIT can effectively treat tumors by blocking the CTLA4-axis as well as by eliminating CTLA4-expressing immune suppressor cells, resulting in T cell mediated antitumor immunity. Local CTLA4-expressing cell depletion in tumor beds using NIR-PIT could be a promising new cancer immunotherapy for safely treating a variety of tumor types.

SUBMITTER: Okada R

PROVIDER: S-EPMC8115697 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature

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Local Depletion of Immune Checkpoint Ligand CTLA4 Expressing Cells in Tumor Beds Enhances Antitumor Host Immunity.

Okada Ryuhei R Kato Takuya T Furusawa Aki A Inagaki Fuyuki F Wakiyama Hiroaki H Choyke Peter L PL Kobayashi Hisataka H

Advanced therapeutics 20210224 5

Near-infrared photoimmunotherapy (NIR-PIT) is a cancer treatment that utilizes antibody-photoabsorber (IR700) conjugates to selectively kill target cells by exposing them to NIR light. Cytotoxic T-lymphocyte antigen 4 (CTLA4) is a major immune checkpoint ligand mediating antitumor immune suppression. Local depletion of CTLA4 expressing cells in the tumor bed with NIR-PIT could enhance antitumor immune responses by both blocking the CTLA4-axis and depleting immune suppressive cells. The aim of th ...[more]

PMID: 33997271

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Project description:PurposeRadiofrequency ablation (RFA) is a minimally invasive energy delivery technique increasingly used for focal therapy to eradicate localized disease. RFA-induced tumor-cell necrosis generates an immunogenic source of tumor antigens known to induce antitumor immune responses. However, RFA-induced antitumor immunity is insufficient to control metastatic progression. We sought to characterize (a) the role of RFA dose on immunogenic modulation of tumor and generation of immune responses and (b) the potential synergy between vaccine immunotherapy and RFA aimed at local tumor control and decreased systemic progression.Experimental designMurine colon carcinoma cells expressing the tumor-associated (TAA) carcinoembryonic antigen (CEA) (MC38-CEA(+)) were studied to examine the effect of sublethal hyperthermia in vitro on the cells' phenotype and sensitivity to CTL-mediated killing. The effect of RFA dose was investigated in vivo impacting (a) the phenotype and growth of MC38-CEA(+) tumors and (b) the induction of tumor-specific immune responses. Finally, the molecular signature was evaluated as well as the potential synergy between RFA and poxviral vaccines expressing CEA and a TRIad of COstimulatory Molecules (CEA/TRICOM).ResultsIn vitro, sublethal hyperthermia of MC38-CEA(+) cells (a) increased cell-surface expression of CEA, Fas, and MHC class I molecules and (b) rendered tumor cells more susceptible to CTL-mediated lysis. In vivo, RFA induced (a) immunogenic modulation on the surface of tumor cells and (b) increased T-cell responses to CEA and additional TAAs. Combination therapy with RFA and vaccine in CEA-transgenic mice induced a synergistic increase in CD4(+) T-cell immune responses to CEA and eradicated both primary CEA(+) and distal CEA(-) s.c. tumors. Sequential administration of low-dose and high-dose RFA with vaccine decreased tumor recurrence compared to RFA alone. These studies suggest a potential clinical benefit in combining RFA with vaccine in cancer patients, and augment support for this novel translational paradigm.

Dataset Information

Local Depletion of Immune Checkpoint Ligand CTLA4 Expressing Cells in Tumor Beds Enhances Antitumor Host Immunity.

Publications

Local Depletion of Immune Checkpoint Ligand CTLA4 Expressing Cells in Tumor Beds Enhances Antitumor Host Immunity.

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