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A subset of T regulatory cells (Tregs), identified by TIRC7 (T cell immune response cDNA 7) expression is designated as Immune Regulatory 1 Cells (IR1 cells). TIRC7 is an immune checkpoint inhibitor, co-localized with the T- cell receptor, HLA-DR and CTLA-4 during T-cell activation, which delivers regulatory signals via binding to its ligand, HLA-DR α 2 domain. IR1 cells express FOXP3, and multiple other markers associated with immune suppression. They constitute as much as 10% of Tregs. IR1 cells strongly inhibit proliferation in mixed lymphocyte reactions, where they express high levels of IL-10. Ex vivo expansion of Tregs over 2 weeks in the presence of an agonist TIRC7 antibody disproportionately expands the IR1 Treg subset, while maintaining high expression of suppressive markers including CD39, IL-10, LAP and GARP. Ex vivo expanded IR1 cells are a potent, homogeneous, stable set of suppressor Tregs with the potential to modulate immune dysregulation. The characteristics of IR1 cells suggest a therapeutic advantage over polyclonal Tregs for therapeutic interventions. Early restoration of immune homeostasis using IR1 cells has the potential to fundamentally alter the natural history of conditions characterized by abnormalities in the T regulatory cell compartment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Krause, Mengwasser, Phithak, Beato, Appis, Milford, Pratschke, Sauer, Kuehl, Vogel, Goodyear, Hammerich, Tacke, Haas, Müller and Utku.)

Cholangiocarcinoma (CCA) is a heterogeneous malignancy with a dismal prognosis. Therapeutic options are largely limited to surgery and conventional chemotherapy offers limited benefit. As immunotherapy has proven highly effective in various cancer types, we have undertaken a quantitative immunohistopathological assessment of immune cells expressing the immunoinhibitory T cell immune response cDNA 7 receptor (TIRC7), an emerging immunoinhibitory receptor, in a cohort of 135 CCA patients. TIRC7 + immune cells were present in both the tumor epithelia and stroma in the majority of CCA cases with the highest levels found in intrahepatic CCA. While intraepithelial density of TIRC7 + immune cells was decreased compared to matched non-neoplastic bile ducts, stromal quantity was higher in the tumor samples. Tumors exhibiting signet ring cell or adenosquamous morphology were exclusively associated with an intraepithelial TIRC7 + phenotype. Survival analysis showed intraepithelial TIRC7 + immune cell density to be a highly significant favorable prognosticator in intrahepatic but not proximal or distal CCA. Furthermore, intraepithelial TIRC7 + immune cell density correlated with the number of intraepithelial CD8 + immune cells and with the total number of CD4 + immune cells. Our results suggest the presence and prognostic relevance of TIRC7 + immune cells in CCA and warrant further functional studies on its pharmacological modulation.

CAP7.1 is a novel topoisomerase II inhibitor, converted to active etoposide via carboxylesterase 2 (CES2), with signals of efficacy in treatment-refractory solid tumours. In a Phase II trial, 27 patients with advanced biliary tract cancers (BTC) were randomised 1:1 to CAP7.1 plus best supportive care (BSC), or BSC alone, with crossover to CAP7.1 upon disease progression. The primary objective was disease control rate (DCR) following 28-day cycles of CAP7.1 (200/150 mg/m 2 ; iv), or BSC until progression. Secondary objectives included progression-free survival (PFS), time-to-treatment failure (TTF), overall survival (OS) and safety. Fourteen patients received CAP7.1 and 13 BSC. DCR favoured CAP7.1 vs. BSC (50% vs. 20%; treatment difference: 30%, 95%CI -18.44, 69.22, full analysis set [FAS]), with disease progression in 40% vs. 70%, respectively. Significantly longer median PFS was achieved for CAP7.1 vs. BSC: 66 vs. 39 days, respectively (hazard ratio [HR] 0.31; 95%CI 0.11, 0.86; p = 0.009; FAS). Similar trends were observed for TTF and OS. CES2-positive patients had longer median PFS (158 vs. 56 days) and OS (228 vs. 82 days) vs. CES2-negative patients. Adverse events were predictable, dose-dependent and consistent with those previously observed with etoposide. These efficacy and safety findings in second-line BTC warrant further clinical investigation of CAP7.1.

Biliary tract carcinoma (BTC) has a poor prognosis and is increasing in incidence. Although surgery, chemotherapy and other treatment modalities have improved, surgery remains the only potential curative treatment and is appropriate for only those few patients who present with localized, resectable disease. However, for the majority of patients, unresectable disease is evident at diagnosis and about 95% of patients die within 10 years, despite the majority receiving chemotherapy. Long-term survival is significantly greater for patients with resected BTC compared to those with unresectable disease. In unresected disease, life expectancy is limited, with first-line gemcitabine/cisplatin (GEM/CIS) accepted as standard of care. Currently no standard second-line regimen which provides significant improvement of clinical outcomes exists for those who present with refractory disease or who relapse after first-line treatment. Of particular importance is establishing the impact of best supportive care (BSC) as a benchmark for survival outcomes to which the impact of treatment modalities can be compared. Survival outcome often differs significantly for patients with different prognostic factor profiles even when receiving the same therapy so that it can be difficult to predict which patient subgroup might benefit most from which therapy. Therefore, the influence of prognostic factors on survival under different therapies as well as under BSC needs to be further assessed in order to arrive at truly evidence-based, best therapeutic decisions for individual patients. Encouraging new research into the genomic landscape of BTC may help to further subdivide the BTC population into molecular-genetic clusters likely to be sensitive to different targeted therapy approaches leading to further improvements in survival. Consequently, an unmet need exists not only to develop new and more effective therapies for this devastating disease, but also to integrate original research findings into a more complex, dynamic, individualized therapeutic decision model to aid clinicians in making evidence-based, best therapeutic decisions for individual patients., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form.(Available at http://dx.doi.org/10.21037/jgo-20-203). NU reports a leadership role, stock ownership, receipt of honoraria and research funding, and holding of patents at CellAct Pharma GmbH. The other authors have no conflicts of interest to declare., (2020 Journal of Gastrointestinal Oncology. All rights reserved.)

Carboxylesterase 2 (CES2) is instrumental for conversion of ester-containing prodrugs in cancer treatment. Novel treatment strategies are exceedingly needed for cholangiocarcinoma (CCA) patients. Here, we assessed CES2 expression by immunohistochemistry in a CCA cohort comprising 171 non-liver fluke associated, intrahepatic (n = 72) and extrahepatic (perihilar: n = 56; distal: n = 43) CCAs. Additionally, 80 samples of high-grade biliary intraepithelial neoplastic tissues and 158 corresponding samples of histological normal, non-neoplastic biliary tract tissues were included. CES2 expression was highest in non-neoplastic biliary tissue and significantly decreased in CCA. Patients showing any CES2 expression in tumor cells had a significantly better overall survival compared to negative cases (p = 0.008). This survival benefit was also maintained after stratification of CES2-positive cases, by comparing low, medium and high CES2 expression levels (p-trend = 0.0006). Evaluation of CCA subtypes showed the survival difference to be restricted to extrahepatic tumors. Correlation of CES2 expression with data of tumor-infiltrating immune cells showed that particularly CD8+ T cells were more frequently detected in CES2-positive CCAs. Furthermore, treatment of CCA cell lines with the prodrug Irinotecan reduced cell viability, increased cytotoxicity and modulated inflammatory gene expression. In conclusion, reduced CES2 expression is associated with poor outcome and low CD8+ T cell infiltration in CCA patients. Further clinical studies could show, whether CES2 expression may serve as a predictive marker in patients treated with prodrugs converted by CES2.

Delivering drugs directly to tumors and overcoming drug resistance are two hurdles that face cancer researchers. Here's a look at where cancer treatment stands.

Classically, HLA-DR expressed on antigen presenting cells (APC) initiates lymphocyte activation via presentation of peptides to TCR bearing CD4+ T-Cells. Here we demonstrate that HLA-DR alpha 2 domain (sHLA-DRalpha2) also induces negative signals by engaging TIRC7 on lymphocytes. This interaction inhibits proliferation and induces apoptosis in CD4+ and CD8+ T-cells via activation of the intrinsic pathway. Proliferation inhibition is associated with SHP-1 recruitment by TIRC7, decreased phosphorylation of STAT4, TCR-zeta chain & ZAP70, and inhibition of IFN-gamma and FasL expression. HLA-DRalpha2 and TIRC7 co-localize at the APC-T cell interaction site. Triggering HLA-DR - TIRC7 pathway demonstrates that sHLA-DRalpha2 treatment inhibits proinflammatory-inflammatory cytokine expression in APC & T cells after lipopolysaccaride (LPS) stimulation in vitro and induces apoptosis in vivo. These results suggest a novel antiproliferative role for HLA-DR mediated via TIRC7, revise the notion of an exclusive stimulatory interaction of HLA-DR with CD4+ T cells and highlights a novel physiologically relevant regulatory pathway.

T cell immune response c-DNA (TIRC7) is up-regulated during the early stages of T-cell activation in response to alloantigens. In this study, we analyzed the effects of newly developed monoclonal antibodies (mAb) against TIRC7 in acute cardiac allograft rejection. Fully vascularized heterotopic allogeneic heart transplantation was performed in mice across a full-mismatch barrier (C57Bl/10 into CBA). Recipients received seven injections (day 0-7) of a novel anti-TIRC7 mAb or remained untreated. Graft survival, histology and ex vivo lymphocyte functions were tested. Targeting of TIRC7 with an anti-TIRC7 mAb diminishes lymphocyte infiltration into grafts resulting in delay of morphological graft damage and prolongation of allograft survival. The lymphocytes from anti-TIRC7 mAb-treated animals exhibit hypo-responsiveness without evidence of lymphocyte depletion against the donor allo-antigens. Proliferation and expression of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) were down-regulated while interleukin-4 (IL-4) and IL-10 expression were spared. Moreover, anti-TIRC7 mAb enhanced up-regulation of CTLA-4 expression but suppressed up-regulation of CD25 on stimulated lymphocytes in vitro and in vivo. Ligation of TIRC7 has important effects on the regulation of co-stimulatory signaling pathways associated with suppressing of T-cell activation. Targeting of TIRC7 may therefore provide a novel therapeutic approach for modulating T cell immune responses during organ transplantation.

Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) is a cell surface molecule that has been proposed to negatively regulate T cell function. We have shown that CEACAM1 is associated with specific regulation of T helper cell (Th)1 pathways, T-bet-mediated Th1 cytokine signaling, and Th1-mediated immunopathology in vivo. Mice treated with anti-mouse CEACAM1-specific monoclonal antibody (mAb) CC1 during the effector phase exhibited a reduced severity of trinitrobenzene sulfonic acid colitis in association with decreased interferon (IFN)-gamma production. Although oxazolone colitis has been reported as Th2 mediated, mice treated with the CC1 mAb or a CEACAM1-Fc chimeric protein exhibited a reduced severity of colitis in association with a significant reduction of IFN-gamma and T-bet activation, whereas signal transducer and activator of antigen 4 activation was unaffected. Both interleukin-4 and IFN-gamma gene-deficient mice exhibited less severe colitis induction by oxazolone. Direct ligation of T cells in vitro with the murine hepatitis virus spike protein, a natural ligand for the N-domain of CEACAM1, inhibited the differentiation of naive cells into Th1 but not Th2 cells and activation of Th1 but not Th2 cytokine production. These results indicate that CEACAM1 isoforms are a novel class of activation-induced cell surface molecules on T cells that function in the specific regulation of Th1-mediated inflammation such as that associated with inflammatory bowel disease.

A novel human membrane protein, TIRC7, was recently identified and demonstrated to be essential in T cell activation. Here we report on the genomic organization of the TIRC7 gene, which is composed of 15 exons and spans 7.9 kb. The seven predicted transmembrane-spanning domains of the TIRC7 protein coincide well with exon-intron boundaries. TIRC7 and OC116, a recently described putative subunit of the vacuolar proton pump that was demonstrated to be expressed in an osteoclastoma tumor as well as in a human pancreatic adenocarcinoma cell line, are demonstrated to be alternative transcripts of the same gene. OC116 consists of 20 exons with the last 14 introns and exons being identical with those of TIRC7. The chromosomal locus for both transcripts was identified on chromosome 11q13.4-q13.5. In human alloactivated T lymphocytes, mRNA expression of TIRC7, but not OC116, is demonstrated, indicating that OC116 is not involved in regular T cell proliferation., (Copyright 1999 Academic Press.)