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Viral Infection of Tumors Overcomes Resistance to PD-1-immunotherapy by Broadening Neoantigenome-directed T-cell Responses.

ABSTRACT: There is evidence that viral oncolysis is synergistic with immune checkpoint inhibition in cancer therapy but the underlying mechanisms are unclear. Here, we investigated whether local viral infection of malignant tumors is capable of overcoming systemic resistance to PD-1-immunotherapy by modulating the spectrum of tumor-directed CD8 T-cells. To focus on neoantigen-specific CD8 T-cell responses, we performed transcriptomic sequencing of PD-1-resistant CMT64 lung adenocarcinoma cells followed by algorithm-based neoepitope prediction. Investigations on neoepitope-specific T-cell responses in tumor-bearing mice demonstrated that PD-1 immunotherapy was insufficient whereas viral oncolysis elicited cytotoxic T-cell responses to a conserved panel of neoepitopes. After combined treatment, we observed that PD-1-blockade did not affect the magnitude of oncolysis-mediated antitumoral immune responses but a broader spectrum of T-cell responses including additional neoepitopes was observed. Oncolysis of the primary tumor significantly abrogated systemic resistance to PD-1-immunotherapy leading to improved elimination of disseminated lung tumors. Our observations were confirmed in a transgenic murine model of liver cancer where viral oncolysis strongly induced PD-L1 expression in primary liver tumors and lung metastasis. Furthermore, we demonstrated that combined treatment completely inhibited dissemination in a CD8 T-cell-dependent manner. Therefore, our results strongly recommend further evaluation of virotherapy and concomitant PD-1 immunotherapy in clinical studies.

SUBMITTER: Woller N

PROVIDER: S-EPMC4817928 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Viral Infection of Tumors Overcomes Resistance to PD-1-immunotherapy by Broadening Neoantigenome-directed T-cell Responses.

Woller Norman N Gürlevik Engin E Fleischmann-Mundt Bettina B Schumacher Anja A Knocke Sarah S Kloos Arnold M AM Saborowski Michael M Geffers Robert R Manns Michael P MP Wirth Thomas C TC Kubicka Stefan S Kühnel Florian F

Molecular therapy : the journal of the American Society of Gene Therapy 20150626 10

There is evidence that viral oncolysis is synergistic with immune checkpoint inhibition in cancer therapy but the underlying mechanisms are unclear. Here, we investigated whether local viral infection of malignant tumors is capable of overcoming systemic resistance to PD-1-immunotherapy by modulating the spectrum of tumor-directed CD8 T-cells. To focus on neoantigen-specific CD8 T-cell responses, we performed transcriptomic sequencing of PD-1-resistant CMT64 lung adenocarcinoma cells followed by ...[more]

PMID: 26112079

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Project description:In this study we have examined how the cytokine interleukin-2 (IL-2) synergizes with programmed cell death-1 (PD-1) directed immunotherapy during chronic lymphocytic choriomeningitis virus (LCMV) infection. PD-1 blockade in combination with IL-2 is one of the most effective combination therapies in this very stringent LCMV mouse model of life-long chronic infection with irreversible T-cell exhaustion. Our paper makes the following points: First, we show that the more effective viral control seen after PD-1/IL-2 combination therapy compared to PD-1 monotherapy is mediated by the CD8+T-cell response. Then we identify the virus-specific CD8+T cells that proliferate and respond to the combination therapy and show that these are the same lymphoid resident PD-1+TCF-1+stem-like CD8+T cells that act as resource cells to maintain the CD8+T-cell response during chronic infection and also respond to PD-1 blockade. However, the combination therapy dramatically changes the differentiation program of these chronic resource CD8+T cells and results in the generation of transcriptionally and epigenetically distinct effector CD8+T cells that resemble highly functional effector CD8+T cells seen after an acute viral infection. In contrast, PD-1 monotherapy doesnot modify the differentiation program and one gets more virus-specific CD8+T cells but they are transcriptionally and epigenetically similar to what is seen in untreated chronically infected mice. This epigenetic inflexibility of exhausted CD8+T cells is a potential barrier to PD-1 therapy and the ability of this combination therapy to modify the epigenetic signature of virus-specific CD8+T cells during chronic infection could be an important determinant of the striking synergy seen between IL-2 therapy and PD-1 blockade. We also highlight the importance of blocking the PD-1/PD-L1 inhibitory pathway at the target site for effective viral control. Expanding the CD8+ Tcell population and generating better effector cells is important but it is also critical to block PD-1 inhibitory signals at the target site for optimal immunotherapy. Finally, we show that CD25 engagement with IL-2 plays an important and essential role in the observed synergy between IL-2 cytokine and PD-1 blockade. Either blocking CD25 with an antibody or using a mutated version of IL-2 that does not bind CD25 but still binds CD122/132 almost completely abrogated the synergistic effects seen after PD-1/IL-2 combination therapy. There is currently considerable interest in PD-1/IL-2 combination therapy for cancer patients and our fundamental studies defining the underlying mechanisms of how IL-2 synergizes with PD-1 blockade should inform these human translational studies.

Dataset Information

Viral Infection of Tumors Overcomes Resistance to PD-1-immunotherapy by Broadening Neoantigenome-directed T-cell Responses.

Publications

Viral Infection of Tumors Overcomes Resistance to PD-1-immunotherapy by Broadening Neoantigenome-directed T-cell Responses.

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