Project description:The CD155/TIGIT axis can be co-opted during immune evasion in chronic viral infections and cancer. Pancreatic adenocarcinoma (PDAC) is a highly lethal malignancy, and immune-based strategies to combat this disease have been largely unsuccessful to date. We corroborate prior reports that a substantial portion of PDAC harbors predicted high affinity MHC class I-restricted neoepitopes and extend these findings to advanced/metastatic disease. Using two novel preclinical models of neoantigen-expressing PDAC, we demonstrate that intratumoral neoantigen-specific CD8+ T cells adopt multiple states of dysfunction, which are similar to tumor-infiltrating lymphocytes of human PDAC patients. Mechanistically, genetic and/or pharmacologic modulation of the CD155/TIGIT axis was sufficient to promote immune evasion in autochthonous neoantigen-expressing PDAC. Finally, we demonstrate that the CD155/TIGIT axis is critical to maintain immune evasion in PDAC and uncover a combination immunotherapy (TIGIT/PD-1 co-blockade plus CD40 agonism) that elicits profound anti-tumor responses in preclinical models, now poised for clinical evaluation.
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses. TIGIT+ and TIGIT- Tregs were sorted from naïve Foxp3-GFP KI mice (pooled spleen and lymph nodes) TIGIT: T cell immunoreceptor with Ig and ITIM domains
Project description:TIGIT+ Tregs suppress Th1 and Th17 responses while sparing Th2 responses. Analysis of global gene expression of TIGIT+ vs. TIGIT- Tregs from naive mice reveled that TIGIT+ Tregs display an activated phenotype and are enriched for Treg signature genes including the Treg effector molecule Fgl2 which enables them to selectively spare Th2 responses.
Project description:Neoantigen-reactive cytotoxic T lymphocytes play a vital role in precise cancer cell elimination. In this study, we demonstrate the effectiveness of personalized neoantigen-based T cell therapy in inducing tumor regression in two patients suffering from heavily-burdened metastatic ovarian cancer. Our approach involved the development of a robust pipeline for ex vivo expansion of neoantigen-reactive T lymphocytes. Neoantigen peptides were designed and synthesized based on the somatic mutations of the tumors and their predicted HLA binding affinities. These peptides were then presented to T lymphocytes through co-culture with neoantigen-loaded dendritic cells for ex vivo expansion. Subsequent to cell therapy, both patients exhibited significant reductions in tumor marker levels and experienced substantial tumor regression. One patient achieved repeated cancer regression through infusions of T cell products generated from newly identified neoantigens. Transcriptomic analyses revealed a remarkable increase in neoantigen-reactive cytotoxic lymphocytes in the peripheral blood of the patients following cell therapy. These cytotoxic T lymphocytes expressed polyclonal T cell receptors (TCR) against neoantigens, along with abundant cytotoxic proteins and pro-inflammatory cytokines. The efficacy of neoantigen targeting was significantly associated with the immunogenicity and TCR polyclonality. Notably, the neoantigen-specific TCR clonotypes persisted in the peripheral blood after cell therapy. Our findings indicate that personalized neoantigen-based T cell therapy triggers cytotoxic lymphocytes expressing polyclonal TCR against ovarian cancer, suggesting its promising potential in cancer immunotherapy.
Project description:We compared the gene expression in wild type CD4+ T cells stimulated with agonistic anti-TIGIT 4D4 antibody to that of isotype and TIGIT-deficient (KO) controls.
Project description:The CD155/TIGIT axis plays a crucial role in the suppression of anti-tumor responses. The clinical benefit for patients with diverse types of advanced cancers that has been observed upon blockade of the interaction between CD155 and TIGIT has highlighted the need to study the mechanisms by which CD155 is regulated. Here we identify Cyclin C (CCNC) as a novel modulator of CD155 by using a genome-wide CRISPR-Cas9 screen. Notably, CCNC depletion increases the CD155 expression at the transcriptional level in a broad range of cancer cells. We further found that CCNC suppresses the CD155 expression by inhibiting the transcriptional activity of FOSL2. We further found that the stability of CCNC is negatively regulated by the E3 ubiquitin ligase complex component FBXO11. Functionally, CCNC depletion significantly suppresses the anti-tumor activity of natural killer (NK) and T cells both in vitro and in vivo. Clinically, the expression level of CCNC is negatively correlated with CD155 in cancer patient tissues. Together, our findings provide insights into the biology of CD155 regulation, identify a previously unrecognized master regulator of this critical immune checkpoint and highlight a combination immunotherapy (TIGIT/PD-1 co-blockade) as a promising anti-cancer therapeutic strategy to overcome immune evasion by CCNC-deficient tumor cells.
Project description:Persistent exposure to antigen leads to T cell exhaustion and immunologic dysfunction. We examined the immune exhaustion markers TIGIT and PD-1 in HIV-infected and healthy individuals and the relationship with cytotoxic CD8+ T lymphocyte (CTL) activity. Frequencies of TIGIT but not PD-1 positively correlated with CTL activity in HIV-aviremic and healthy individuals; however, there was no correlation in HIV-viremic individuals. Transcriptome analyses revealed upregulation of genes associated with antiviral immunity in TIGIT+ versus TIGIT-CD8+ T cells. Our data suggest that TIGIT+CD8+ T cells do not necessarily represent a state of immune exhaustion and maintain an intrinsic cytotoxicity in HIV-infected individuals.
Project description:Combination immunotherapy based on immune checkpoint inhibitors (ICIs) has shown great success in the treatment of many types of cancers and has become the mainstream in the comprehensive treatment of cancers. Ablation in combination with immunotherapy has achieved tremendous efficacy in some preclinical and clinical studies. To date, our team proved that ablation in combination with ICIs was a promising antitumor therapeutic strategy for the liver metastasis of colorectal cancer (CRC). Moreover, we found that the expression of T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) expression was up-regulated after microwave ablation (MWA), indicating that TIGIT was involved in immunosuppression, and the combination of MWA and TIGIT blockade represented a potential clinical treatment strategy. In this study, we analyzed the single-cell RNA sequencing (scRNA-seq) data from the MWA and MWA plus anti-TIGIT groups. We found that TIGIT blockade in combination with MWA significantly promoted the expansion and functions of CD8+ TILs and reshaped myeloid cells in the tumor microenvironment (TME). In conclusion, TIGIT blockade in combination with MWA was a novel treatment strategy for the liver metastasis of CRC, and this combination therapy could reprogram the TME toward an antitumor environment.
Project description:Regulatory B cells (Bregs) contribute to immune regulation. However, the mechanisms of action of Bregs remain elusive. Here, we report that T cell immunoreceptor with Ig and ITIM domains (TIGIT) expressed on human memory B cells especially CD19+CD24hiCD27+CD39hiIgD−IgM+CD1c+ B cells is essential for effective immune regulation. Mechanistically, TIGIT on memory B cells controls immune response by directly acting on T cells and by arresting proinflammatory function of dendritic cells, resulting in the suppression of Th1, Th2, Th17, and CXCR5+ICOS+ T cell response while promoting immune regulatory function of T cells. TIGIT+ memory B cells are also superior to other B cells at expressing additional inhibitory molecules, including IL-10, TGFβ1, granzyme B, PD-L1, CD39/CD73, and TIM-1. Lack or decrease of TIGIT+ memory B cells is associated with increased donor-specific antibody and TFH response, and decreased Treg response in renal and liver allograft patients. Therefore, TIGIT+ human memory B cells play critical roles in immune regulation.