Highlights d Host macrophages (Mf) are indispensable for BM-MSCdependent reduction of colitis d MSC-secreted chemokines CCL2 and CXCL12 synergistically induce M2 polarization d Host IL-10 competency is crucial for MSC-mediated recovery of DSS colitis d MSC-polarized host Mf regulate IL-10 polarization by gutbound lymphoid cells

SummaryAdoptive transfer of T‐cells is a promising therapy for many cancers. To enhance tumour recognition by T‐cells, chimeric antigen receptors (CARs) consisting of signalling domains fused to receptors that recognize tumour‐associated antigens can be expressed in T‐cells. While CAR T‐cells have shown clinical success for treating haematopoietic malignancies, using CAR T‐cells to treat solid tumours remains a challenge. We developed a chimeric PD1 (chPD1) receptor that recognizes the ligands for the PD1 receptor that are expressed on many types of solid cancer. To determine if this novel CAR could target a wide variety of tumour types, the anti‐tumour efficacy of chPD1 T‐cells against syngeneic murine models of melanoma, renal, pancreatic, liver, colon, breast, prostate and bladder cancer was measured. Of the 14 cell lines tested, all expressed PD1 ligands on their cell surface, making them potential targets for chPD1 T‐cells. ChPD1 T‐cells lysed the tumour cells and secreted pro‐inflammatory cytokines [interferon (IFN)γ, tumour necrosis factor (TNF)α, interleukin (IL)‐2, granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), IL‐17 and IL‐21], but did not secrete the anti‐inflammatory cytokine IL‐10. Furthermore, T‐cells expressing chPD1 receptors reduced an established tumour burden and led to long‐term tumour‐free survival in all types of solid tumours tested. ChPD1 T‐cells did not survive longer than 14 days in vivo; however, treatment with chPD1 T‐cells induced protective host anti‐tumour memory responses in tumour‐bearing mice. Therefore, adoptive transfer of chPD1 T‐cells could be a novel therapeutic strategy to treat multiple types of solid cancer.

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Adoptive transfer of T cells is a promising cancer therapy and expression of chimeric antigen receptors can enhance tumour recognition and T-cell effector functions. The programmed death protein 1 (PD1) receptor is a prospective target for a chimeric antigen receptor because PD1 ligands are expressed on many cancer types, including lymphoma. Therefore, we developed a murine chimeric PD1 receptor (chPD1) consisting of the PD1 extracellular domain fused to the cytoplasmic domain of CD3ζ. Additionally, chimeric antigen receptor therapies use various co-stimulatory domains to enhance efficacy. Hence, the inclusion of a Dap10 or CD28 co-stimulatory domain in the chPD1 receptor was compared to determine which domain induced optimal anti-tumour immunity in a mouse model of lymphoma. The chPD1 T cells secreted pro-inflammatory cytokines and lysed RMA lymphoma cells. Adoptive transfer of chPD1 T cells significantly reduced established tumours and led to tumour-free survival in lymphoma-bearing mice. When comparing chPD1 receptors containing a Dap10 or CD28 domain, both receptors induced secretion of pro-inflammatory cytokines; however, chPD1-CD28 T cells also secreted anti-inflammatory cytokines whereas chPD1-Dap10 T cells did not. Additionally, chPD1-Dap10 induced a central memory T-cell phenotype compared with chPD1-CD28, which induced an effector memory phenotype. The chPD1-Dap10 T cells also had enhanced in vivo persistence and anti-tumour efficacy compared with chPD1-CD28 T cells. Therefore, adoptive transfer of chPD1 T cells could be a novel therapy for lymphoma and inclusion of the Dap10 co-stimulatory domain in chimeric antigen receptors may induce a preferential cytokine profile and T-cell differentiation phenotype for anti-tumour therapies.

Adoptive transfer of tumor-reactive T cells is a promising anti-tumor therapy for many cancers. To enhance tumor recognition by T cells, chimeric antigen receptors (CAR) consisting of signaling domains fused to receptors that recognize tumor antigens can be created and expressed in T cells. One receptor that is a prospective target for a new chimeric antigen receptor is PD1 because the ligands for the PD1 receptor are expressed on many cancer types. Therefore we developed a murine chimeric PD1 receptor (chPD1) consisting of the PD1 receptor extracellular ligand recognition domain and the activation domain of CD3 zeta. In addition, current chimeric antigen receptor therapies utilize various costimulatory domains to enhance anti-tumor efficacy. Therefore, we also compared the inclusion of CD28, Dap10, 41BB, GITR, ICOS, or OX40 costimulatory domains in our chPD1 receptor to determine which costimulatory domain induced optimal anti-tumor immunity. To determine if this novel CAR could potentially target a wide variety of tumors, the anti-tumor efficacy of chPD1 T cells against murine lymphoma, melanoma, kidney, pancreatic, liver, and colon cancer cell lines was measured. Of the ten cell lines tested, all expressed PD1 ligands on their cell surface, making them potential targets for chPD1 T cells. Regardless of the costimulatory domain in the CAR, all of the chPD1 T cells induced similar levels of T cell proliferation and tumor cell lysis. However, differences were observed in the cytokine secretion profiles depending on which costimulatory receptor was included in the CAR. While most of the chPD1 T cell receptor combinations secreted both pro-inflammatory (IFNγ, TNFα, IL-2, GM-CSF, IL-17, and IL-21) and anti-inflammatory cytokines (IL-10 and IL-5) as determined by ELISA and LegendPlex analysis, chPD1 T cells containing a Dap10 costimulatory domain secreted high levels of proinflammatory cytokines, but did not secrete a significant amount of anti-inflammatory cytokines. Therefore, adoptive transfer of chPD1 T cells could be a novel therapeutic strategy to treat multiple types of cancer and inclusion of the Dap10 costimulatory domain in chimeric antigen receptors may induce a preferential cytokine profile for anti-tumor therapies. Citation Format: Kelsey Deal, Emily Nylen, Amorette E. Barber. T cells expressing chimeric PD1 receptors that contain a Dap10 costimulatory domain are a potential treatment for multiple types of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4983. doi:10.1158/1538-7445.AM2017-4983