Single-cell immune mapping of adenoid cystic carcinoma (ACC) reveals potential therapeutic targets for the aggressive solid subtype

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Background: ACC is a common salivary gland malignancy for which there is no FDA approved therapies. Despite a quiet genome, ACC has significant tumoral heterogeneity, which may facilitate the metastatic relapse. Studies focusing on the deep profile of ACC tumor microenvironment (TME) are lacking. Here we explored the TME of ACC using imaging mass cytometry (IMC) and assessed TME attributes and its association with histology and clinical outcomes. Methods: Two tissue microarrays from 62 ACC patients (pts) were built and stained with 37 metal-tagged markers. IMC was performed with the Fluidigm Helios CyTOF instrument utilizing the Hyperion Imaging System Laser ablation. Tissue and cell segmentation and multiplex imaging analysis were performed with Visiopharm software using pre-trained artificial intelligence algorithms. Comparison of cell types and markers densities among histology sub-groups were analyzed with Wilcoxon signed-rank test and its association with overall survival (OS) with log-rank and Cox Proportional Hazards. Results: Of 62 pts, 37% (23/62) had solid histology, 19% (12/62) were metastatic at diagnosis, and 55% (30/54) had disease recurrence during follow-up. With a median follow-up of 7.9 y, the median OS was 9.3y (CI 95%, 7.8-NR). Pts with solid subtype had poorer OS than non-solid histology (5.2 vs 14.6 y, p = 0.004). The IMC final dataset comprised 507,524 single-cells. No significant differences were found in cell subpopulations density between solid and non-solid histology. The most represented cell population in the stroma were macrophages, followed by CD8+ T cells, and fibroblasts. A higher percentage of M2-macrophage was associated with poor survival (p = 0.001), whereas, a higher percentage of M1-macrophage (M1:M2 ratio) was associated with better prognosis. No other immune cell type, fibroblasts or immune cell functional markers (TIGIT, TIM3, granzyme B, and PD-L1) correlated with survival. Regarding tumor markers, a higher expression of BCL-2, B7-H4, and Ki67 in the tumor cells were associated with worst survival; and remained statistically associated after adjustment for histology and staging (all p < 0.001). Solid histology had a significantly higher density of tumor cells expressing B7-H4, BCL-2, and Ki67 compared to cribriform and tubular histology. A higher expression of myoepithelial marker (p63+) were associated with a better survival when compared with tumors with low p63 expression. Conclusions: ACC’s TME is composed mainly of macrophages. Despite having no significant differences in cellular composition, a higher density of tumor cells expressing BCL-2, B7-H4 and Ki67 were found in the solid histology and these markers were independent predictors of poor prognosis. The overexpression of BCL-2 and B7-H4 in the solid histology provides a scientific rationale for BCL-2 and/or B7-H4 targeting for the most aggressive ACC.

Abstract 2232: A novel immune checkpoint regulator in the ovarian cancer microenvironment

High-grade serous ovarian cancer (HGSC) is the most lethal gynecologic malignancy, accounting for 70-80% of ovarian cancer deaths worldwide. Despite promising results with platinum-based chemotherapy and cytoreductive surgery, more than 75% of women with HGSC will relapse after completion of first-line therapy. The window of opportunity to tailor therapeutic interventions to control progressive disease is limited due to the inherent tumor heterogeneity and genomic instability of HGSC and to how these factors contribute to different immune responses. Recent studies show that biomarkers expressed by specific stromal cell types in the tumor microenvironment may have prognostic value. Our group and others has shown that CD8+ lymphocyte infiltration in the ovarian tumor epithelium is associated with prolonged survival in patients with HGSC. Nevertheless, the molecular mechanisms underlying the promotion or inhibition of CD8+ lymphocyte infiltration by stromal cells in ovarian cancer are not fully understood.By laser microdissection and transcriptome profiling of tumor tissue samples from HGSC patients, we identified stromal cancer associated fibroblasts (CAF)-specific gene signatures that are associated with the survival of patients and with the differential tumor immune response. Among the differentially expressed genes identified, validation study by qPCR, Imaging CyTOF and immunohistochemistry indicated a significant inverse correlation between stromal MFAP5 expression and intratumoral granzyme B+/CD8+ T cell density in HGSC tissue samples. MFAP5 is an extracellular matrix glycoprotein and an important component in the assembly of microfibrils. Moreover our recent studies showed that increased stromal MFAP5 expression is associated with poorer survival in HGSC patients. This led to the hypothesis that MFAP5 could acts as an immune checkpoint mediator by generating an immunosuppressive environment through suppressing CD8+ T cell activation and trafficking in the ovarian tumor tissue. To test this hypothesis, transcriptome profile was performed to identify alteration in immune related genes in ovarian cancer cells treated with rMFAP5. The results showed markedly higher expression of CD47, a novel immune checkpoint molecule that triggers “don't eat me” signals on macrophages, in rMFAP5 treated ovarian cancer cells and CD8+ T cells than control cells. Additionally, we demonstrated that rMFAP5 induced apoptosis in CD8+ T cells and reduced macrophage phagocytosis potential. These data suggest that CD47 mediates the effect of MFAP5 on inducing apoptosis in CD8+ T-cells as wells as on preventing macrophage phagocytosis of ovarian cancer cells.Overall, the identification of MFAP5 as a novel stroma-derived immunomodulatory molecule that is associated with patient survival rates and CD8+ T cell densities presents a unique opportunity for the development of new treatment strategies that may improve survival.

Citation Format: Sammy Ferri Borgogno, Tsz-Lun Yeung, Cecilia S. Leung, Chi Lam Au Yeung, Ying Zhu, Stephen T. Wong, Samuel C. Mok. A novel immune checkpoint regulator in the ovarian cancer microenvironment [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2232.

Abstract B045: A novel immune checkpoint regulator in the ovarian cancer microenvironment

High-grade serous ovarian cancer (HGSC) is the most lethal gynecologic malignancy, accounting for 70–80% of ovarian cancer deaths worldwide. Despite promising results with platinum-based chemotherapy and cytoreductive surgery, more than 75% of women with HGSC will relapse after completion of first-line therapy. The window of opportunity to tailor therapeutic interventions to control progressive disease is limited due to the inherent tumor heterogeneity and genomic instability of HGSC and to how these factors contribute to different immune responses. Recent studies show that biomarkers expressed by specific stromal cell types in the tumor microenvironment may have prognostic value. CD8+ tumor-infiltrating lymphocytes are associated with improved overall survival and have been described in several solid tumors, including HGSC. Nevertheless, the molecular mechanisms underlying the promotion or inhibition of CD8+ lymphocyte infiltration by stromal cells in ovarian cancer are not fully understood. By laser microdissection and transcriptome profiling of tumor tissue samples from HGSC patients, we identified stromal cancer associated fibroblasts (CAF)-specific gene signatures for ovarian cancer that are associated with the survival of patients and with the differential tumor immune response. Among the differentially expressed genes identified, validation study by qPCR, Imaging CyTOF and immunohistochemistry indicated a significant inverse correlation between stromal MFAP5 expression and intratumoral CD8+ T cell density in HGSC tissue samples. MFAP5 is an extracellular matrix glycoprotein and an important component in the assembly of microfibrils. Moreover our recent studies showed that increased stromal MFAP5 expression is associated with poorer survival in HGSOC patients. This led to the hypothesis that MFAP5 could acts as an immune checkpoint mediator by generating an immunosuppressive environment through suppressing CD8+ T cell activation and trafficking in the ovarian tumor tissue. To test this hypothesis, transcriptome profile was performed to identify alternation in immune related genes in ovarian cancer cells treated with rMFAP5. The results showed markedly higher CD47 expression in rMFAP5 treated cells than control cells. CD47 is an integral membrane protein, in both cancer cells and CD8+ T cells. It has been demonstrated to induce apoptosis in CD8+ T cells and trigger inhibitory signals on macrophages to prevent phagocytosis of cancer cells, thus disabling the possibility to activate CD8+ T-cells. We therefore hypothesize that CD47 mediates the effect of MFAP5 on inducing apoptosis in CD8+ T-cells as wells as on preventing macrophage phagocytosis of ovarian cancer cells. Overall, the identification of MFAP5 as a novel stroma-derived immunomodulatory molecule that is associated with patient survival rates and CD8+ T cell densities presents a unique opportunity for the development of new treatment strategies that may improve survival.

Citation Format: Sammy Ferri Borgogno, Tsz-Lun Yeung, Cecilia S Leung, Chi Lam Au Yeung, Ying Zhu, Stephen T Wong, Samuel C Mok. A novel immune checkpoint regulator in the ovarian cancer microenvironment [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B045. doi:10.1158/1535-7163.TARG-19-B045

Endogenous glutamine decrease is associated with pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is becoming the second leading cause of cancer-related death in the Western world. The mortality is very high, which emphasizes the need to identify biomarkers for early detection. As glutamine metabolism alteration is a feature of PDAC, its in vivo evaluation may provide a useful tool for biomarker identification. Our aim was to identify a handy method to evaluate blood glutamine consumption in mouse models of PDAC. We quantified the in vitro glutamine uptake by Mass Spectrometry (MS) in tumor cell supernatants and showed that it was higher in PDAC compared to non-PDAC tumor and pancreatic control human cells. The increased glutamine uptake was paralleled by higher activity of most glutamine pathway-related enzymes supporting nucleotide and ATP production. Free glutamine blood levels were evaluated in orthotopic and spontaneous mouse models of PDAC and other pancreatic-related disorders by High-Performance Liquid Chromatography (HPLC) and/or MS. Notably we observed a reduction of blood glutamine as much as the tumor progressed from pancreatic intraepithelial lesions to invasive PDAC, but was not related to chronic pancreatitis-associated inflammation or diabetes. In parallel the increased levels of branched-chain amino acids (BCAA) were observed. By contrast blood glutamine levels were stable in non-tumor bearing mice. These findings demonstrated that glutamine uptake is measurable both in vitro and in vivo. The higher in vitro avidity of PDAC cells corresponded to a lower blood glutamine level as soon as the tumor mass grew. The reduction in circulating glutamine represents a novel tool exploitable to implement other diagnostic or prognostic PDAC biomarkers.

Abstract A042: Targeting of alpha-enolase (ENO1) as a novel immunotherapeutical strategy for pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by rapid progression, invasiveness, and resistance to treatment. By using a proteome approach, we have found that protein recognized with the highest frequency by autoantibodies in PDAC sera was the alpha-enolase (ENO1), a glycolytic enzyme that also acts as a plasminogen-binding receptor. We have found that either ENO1 silencing or treatment of the PDAC cells with single administration of Adeno-Associated Virus-expressing monoclonal antibody against human ENO1 inhibited lung metastasis in immunosuppressed mice injected with PDAC cells. In addition, PDAC ENO1-silenced cells displayed a down modulated expression of cell surface molecules that regulate the adhesion to the extracellular matrix as confirmed by their reduced binding to laminin, collagen and fibronectin. ENO1 silencing in PDAC cells increased reactive oxygen species mainly generated through the sorbitol and NADPH oxidase pathways, as well as autophagy and catabolic pathway adaptations, which together affect PDAC cell growth and induced senescence. This data indicated that ENO1 plays a critical role in PDAC progression and invasion. ENO1 possesses interesting antigenic properties as it is able to elicit T cell proliferation, activation and cytotoxic specific T lymphocytes (CTL) differentiation both in vitro and in vivo. Tumor infiltrating T lymphocytes specific for ENO1 have been identified in PDAC patients and the number of ENO1-specific T cell clones generated from peripheral blood of PDAC positively correlated with a better survival. Antibody and T cell responses to ENO1 are increase in PDAC patient underwent chemotherapy. DNA vaccination to ENO1 elicits an integrated humoral and cellular immune response that was accompanied by a reduced and regulatory T cells and MDSC that significantly extends survival of Genetically Engineered Mice that spontaneously develop PDAC. Notably, mouse anti-human ENO1 monoclonal antibody inhibits MDSC adhesion to pancreatic endothelial cells and in vitro and in vivo migration and decreases MDSC arginase activity and secretion of IL-6. As whole these data demonstrate that the self-antigen ENO1 is a promising target suitable for therapeutic purposes in PDAC. In particular, the antibodies anti-ENO1 may inhibit PDA cell and myeloid cell invasion and positively modulate T cell response, making the immunotherapy more effective.

Citation Format: Francesco Novelli, Michela Capello, Michelle Chattaragada, Sammy Ferri Borgogno, Giorgia Mandili, Moitza Principe, Emanuela Mazza, Sara Bulfamante, Roberta Curto, Daniele Giordano, Paola Cappello. Targeting of alpha-enolase (ENO1) as a novel immunotherapeutical strategy for pancreatic cancer [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A042.