Tumor-infiltrating Myeloid Cells Research Articles

A single-cell pan-cancer analysis to show the variability of tumor-infiltrating myeloid cells in immune checkpoint blockade

Myeloid cells are vital components of the immune system and have pivotal functions in orchestrating immune responses. Understanding their functions within the tumor microenvironment and their interactions with tumor-infiltrating lymphocytes presents formidable challenges across diverse cancer types, particularly with regards to cancer immunotherapies. Here, we explore tumor-infiltrating myeloid cells (TIMs) by conducting a pan-cancer analysis using single-cell transcriptomics across eight distinct cancer types, encompassing a total of 192 tumor samples from 129 patients. By examining gene expression patterns and transcriptional activities of TIMs in different cancer types, we discern notable alterations in abundance of TIMs and kinetic behaviors prior to and following immunotherapy. We also identify specific cell-cell interaction targets in immunotherapy; unique and shared regulatory profiles critical for treatment response; and TIMs associated with survival outcomes. Overall, our study illuminates the heterogeneity of TIMs and improves our understanding of tissue-specific and cancer-specific myeloid subsets within the context of tumor immunotherapies.

Type I Interferon Activates PD-1 Expression through Activation of the STAT1-IRF2 Pathway in Myeloid Cells.

PD-1 (Programmed cell death protein 1) regulates the metabolic reprogramming of myeloid-derived suppressor cells and myeloid cell differentiation, as well as the type I interferon (IFN-I) signaling pathway in myeloid cells in the tumor microenvironment. PD-1, therefore, is a key inhibitory receptor in myeloid cells. However, the regulation of PD-1 expression in myeloid cells is unknown. We report that the expression level of PDCD1, the gene that encodes the PD-1 protein, is positively correlated with the levels of IFNB1 and IFNAR1 in myeloid cells in human colorectal cancer. Treatment of mouse myeloid cell lines with recombinant IFNβ protein elevated PD-1 expression in myeloid cells in vitro. Knocking out IFNAR1, the gene that encodes the IFN-I-specific receptor, diminished the inductive effect of IFNβ on PD-1 expression in myeloid cells in vitro. Treatment of tumor-bearing mice with a lipid nanoparticle-encapsulated IFNβ-encoding plasmid (IFNBCOL01) increased IFNβ expression, resulting in elevated PD-1 expression in tumor-infiltrating myeloid cells. At the molecular level, we determined that IFNβ activates STAT1 (signal transducer and activator of transcription 1) and IRFs (interferon regulatory factors) in myeloid cells. Analysis of the cd279 promoter identified IRF2-binding consensus sequence elements. ChIP (chromatin immunoprecipitation) analysis determined that the pSTAT1 directly binds to the irf2 promoter and that IRF2 directly binds to the cd279 promoter in myeloid cells in vitro and in vivo. In colon cancer patients, the expression levels of STAT1, IRF2 and PDCD1 are positively correlated in tumor-infiltrating myeloid cells. Our findings determine that IFNβ activates PD-1 expression at least in part by an autocrine mechanism via the stimulation of the pSTAT1-IRF2 axis in myeloid cells.

ΔNp63-restricted viral mimicry response impedes cancer cell viability and remodels tumor microenvironment in esophageal squamous cell carcinoma

Tumor protein p63 isoform ΔNp63 plays roles in the squamous epithelium and squamous cell carcinomas (SCCs), including esophageal SCC (ESCC). By integrating data from cell lines and our latest patient-derived organoid cultures, derived xenograft models, and clinical sample transcriptomic analyses, we identified a novel and robust oncogenic role of ΔNp63 in ESCC. We showed that ΔNp63 maintains the repression of cancer cell endogenous retrotransposon expression and cellular double-stranded RNA sensing. These subsequently lead to a restricted cancer cell viral mimicry response and suppressed induction of tumor-suppressive type I interferon (IFN–I) signaling through the regulations of Signal transducer and activator of transcription 1, Interferon regulatory factor 1, and cGAS-STING pathway. The cancer cell ΔNp63/IFN-I signaling axis affects both the cancer cell and tumor-infiltrating immune cell (TIIC) compartments. In cancer cells, depletion of ΔNp63 resulted in reduced cell viability. ΔNp63 expression is negatively associated with the anticancer responses to viral mimicry booster treatments targeting cancer cells. In the tumor microenvironment, cancer cell TP63 expression negatively correlates with multiple TIIC signatures in ESCC clinical samples. ΔNp63 depletion leads to increased cancer cell antigen presentation molecule expression and enhanced recruitment and reprogramming of tumor-infiltrating myeloid cells. Similar IFN-I signaling and TIIC signature association with ΔNp63 were also observed in lung SCC. These results support the potential application of ΔNp63 as a therapeutic target and a biomarker to guide candidate anticancer treatments exploring viral mimicry responses.

Tumor cells inhibit the activation of ILC2s through up-regulating PD-1 expression

Objective Up-regulating programmed cell death ligand-1(PD-L1) expressed on tumor cells and tumor-infiltrating myeloid cells interacting with up-regulated programmed cell death-1 (PD-1) expressed on tumor-infiltrating lymphoid cells greatly hinder their tumor-inhibiting effect. It is necessary to explore the deep mechanism of this negative effect, so as to find the potential methods to improve the immunotherapy efficiency. Methods and Results In this study, we found that the PD-1 expression in lung cancer-infiltrating type II innate lymphoid cells (ILC2s) was highly up-regulated, which greatly restrained the activation and function of ILC2s. Furthermore, anti-PD-1 could restore the inhibition and effective cytokine secretion of ILC2s when co-cultured with tumor cells. In vivo studies proved that anti-PD-1 treatment promoted the activation of tumor-infiltrating ILC2s and inhibited the tumor growth of LLC-bearing nude mice. Discussion Our studies demonstrate a new PD-1/PD-L1 axis regulating mechanism on innate immune cells, which provide a useful direction to ILC2s-based immunotherapy to cancer diseases.

Key players of immunosuppression in epithelial malignancies: Tumor-infiltrating myeloid cells and γδ T cells.

The tumor microenvironment of solid tumors governs the differentiation of otherwise non-immunosuppressive macrophages and gamma delta (γδ) T cells into strong immunosuppressors while promoting suppressive abilities of known immunosuppressors such as myeloid-derived suppressor cells (MDSCs) upon infiltration into the tumor beds. In epithelial malignancies, tumor-associated macrophages (TAMs), precursor monocytic MDSCs (M-MDSCs), and gamma delta (γδ) T cells often acquire strong immunosuppressive abilities that dampen spontaneous immune responses by tumor-infiltrating T cells and B lymphocytes against cancer. Both M-MDSCs and γδ T cells have been associated with worse prognosis for multiple epithelial cancers. Here we discuss recent discoveries on how tumor-associated macrophages and precursor M-MDSCs as well as tumor associated-γδ T cells acquire immunosuppressive abilities in the tumor beds, promote cancer metastasis, and perspectives on how possible novel interventions could restore the effective adaptive immune responses in epithelial cancers.

Abstract LB313: Immunosuppressive effect of tumor-infiltrating IL-22 receptor-expressing myeloid cells in early-stage pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with a poor survival rate, largely due to the lack of diagnostic biomarker for early detection. Here, we found enriched IL-10R2+/IL-22R1+ myeloid cells in peripheral blood and specifically PDAC tissues respectively using xenograft/orthotropic PDAC mouse models. The subcutaneous injection of PDAC cell line in mouse showed a positive correlation of pancreatic tumor growth with increased IL-10R2+/IL-22R1+ myeloid cells by flow cytometry. We also verified that IL-10R2+CD45+ and IL-22R1+CD45+ myeloid cells were infiltrated in tumor tissues after 2 weeks and 3 weeks of injection in orthotropic murine PDAC model. Notably, the IL-10R2+IL-22R1+ cells were highly detected in tumor tissues after 7 days of injection, an earlier time point of PDAC progression. To define whether these cells have immunosuppressive functions to contribute further PDAC progression, IL-10R2+/IL-22R1+ myeloid cells were sorted from splenocytes after 3 days of tumor implantation and co-cultured with T cells in the presence of T cell receptor triggering. The proliferation and cytotoxicity of CD8+ T cells were alleviated by co-culture with IL-10R2+, IL-22R1+, or IL-10R2+IL-22R1+ myeloid cells, compared to that with IL-10R2-IL-22R1- cells. In addition, the population of regulatory T cells was increased when they were co-cultured with IL-22R1+ myeloid cells. Furthermore, the proliferation of human T cells in vitro was also inhibited by co-culture with IL-10R2+/IL-22R1+ myeloid cells from human peripheral blood, indicating the immunosuppressive function of IL-10R2+/IL-22R1+ cell population. Therefore, IL-10R2+/IL-22R1+ myeloid cell population could be a possible promising early detection marker for PDAC, contributing to the non-immunogenic features of tumor microenvironment during PDAC progression. Citation Format: Yoolim Sung, Ji-Eun Kim, Hyo-Jin Min, Soo-Hyun Chung, Seong Who Kim, Eun-Ju Chang. Immunosuppressive effect of tumor-infiltrating IL-22 receptor-expressing myeloid cells in early-stage pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB313.

Abstract 1393: Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive colorectal cancer

Abstract Mesenchymal subtype of colorectal cancer (CRC) is characterized by high metastatic potential, poor prognosis and an immunosuppressive tumor microenvironment (TME). Although tumor-infiltrating myeloid cells constitute the primary population of immune components in the TME, targeting myeloid cells remains highly challenging owing to the developmental and functional heterogeneity of their subsets. Thus, a deeper understanding of how tumor-infiltrating myeloid cells contribute to the creation of a tumor-promoting TME is needed to identify rational strategies against CRCs with aggressive phenotypes. Recent studies have revealed that multiple inflammatory signatures are elevated in mesenchymal CRCs, suggesting a strong association between inflammation and stromal activation. In this study, we focus on thrombospondin-1 (THBS1), which is a matricellular protein, typically expressed in inflammatory processes. Immunostaining and RNA in situ hybridization on human CRC samples revealed a clear localization of THBS1 expression in tumor stroma. Analyses of the cancer genome atlas (TCGA) and tissue microarray of human CRCs show a positive correlation between increased expression of THBS1 and the mesenchymal phenotype, immunosuppression, and poor prognosis in human CRCs. Utilizing immunocompetent orthotopic implantation systems with aggressive mouse tumor organoids (MTO) on wild-type and Thbs1 knockout (Thbs1−/−) mice, we demonstrated that loss of THBS1 in the TME suppressed metastatic formation accompanied by an increased infiltration of tumor-infiltrating CD8+ T cells. Depletion of CD8+ T cells by neutralizing antibody restored metastases in MTO-bearing Thbs1−/− mice, indicating that THBS1 promotes metastatic formation by suppressing CD8+ T cell-mediated anti-tumor immunity. Analyses of single cell RNA sequencing data of human CRCs and orthotopic MTO tumors revealed that bone marrow (BM)-derived monocyte-like cells are the primary source of THBS1. This notion was further supported by analyzing the orthotopic MTO tumors in chimeric mice generated by bone marrow transplantation. Finally, we identified stroma-derived CXCL12 as a key chemokine for the recruitment of THBS1-producing monocyte-like cells by analyzing orthotopic MTO tumors treated with CXCL12 inhibitor. Our study contributes to a better understanding of the processes underlying THBS1 production by monocyte-like cells that mediates immune evasion that confer aggressive features to CRCs. These findings provide insights for the treatment of this poor-prognosis malignancy. Citation Format: Mayuki Omatsu, Yuki Nakanishi, Kosuke Iwane, Naoki Aoyama, Takahisa Maruno, Hiroaki Kasashima, Masakazu Yashiro, Akihisa Fukuda, Hiroshi Seno. Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1393.

Abstract 1530: Tumor cell line-derived xenograft subtype shapes tumor microenvironment composition in BRGSF-HIS mice

Abstract The relevance of preclinical models has vastly improved with mice bearing a human immune system, especially in the context of immunotherapy. BRGSF (Balb/C Rag2−/−, IL2Rγ−/−, SIRPαNOD and Flt3−/−) is a highly immunodeficient mouse featuring reduced murine myeloid cells. BRGSF mice reconstituted with human cord blood CD34+ cells (BRGSF-HIS) develop functional lymphoid and myeloid compartments. This engraftment is stable for over a year (Labarthe et al., 2019) and mice do not develop GvHD. Myeloid compartment can be transiently boosted with exogenous human Flt3L injections. In contrary to other models overexpressing human cytokines to develop human myeloid cells, Flt3L-treated BRGSF-HIS mice do not show side effects. BRGSF-HIS mice are permissive to mouse and human cancer cell lines engraftment and represent a valuable preclinical model to study cancer development and test novel therapeutics. Effect of Flt3L-induced boost on myeloid compartment is seen in a non-small cell lung cancer (A549) tumor model. A single boost prior to tumor cell inoculation associates with increased tumor-infiltrating T-cells (mainly CD8+ T-cells) and myeloid cells, and reduced tumor-infiltrating NK cells in the tumor microenvironment (TME). Human triple negative cancer cell (TNBC) MDA-MB-231 and human pancreatic adenocarcinoma HPAFII cell lines are widely used in cancer research and drug development. We show that upon implantation in BRGSF-HIS mice, in vivo growth of human cell line-derived xenograft (CDX) is CD34+ donor independent and the TME composition varies according to cell line used. As seen in TNBC patients (Zheng et al., 2021); TME of MDA-MB-231 bearing BRGSF-HIS mice is enriched in myeloid cells, mostly CD206+/CD163+ M2 macrophages. CD163-expressing M2 macrophages represent the main tumor-associated macrophages, and are known to promote breast cancer initiation, angiogenesis, invasion, and metastasis by generating an immunosuppressive TME. Interestingly, TME composition evolves over time, with increased T cells frequency in later stage (tumor volume over 1000 mm3 compared to 500 mm3) depicting cancer cell plasticity. Conversely, TME of HPAFII bearing mice is mainly composed of T cells enabling T cells-based therapy. Treatment of BRGSF-HIS mice bearing HPAFII tumor cells with combotherapy based on CD3xTAA + CD28xTAA efficiently reduces tumor growth in vivo compared to vehicle-treated mice or mice injected with CD3xTAA alone. Induced systemic immunomodulation is observed in the TME where increased numbers of both CD4 and CD8 T cells are observed upon combotherapy. Remarkably, while no CD34+ donor effect is observed in CDX growth kinetic, response to treatment appears to be donor dependent with apparition of “weak” and “good” responders. This heterogeneity of response mimics what is observed in clinic and enables further investigations of treatment mode of action and immune escape mechanisms. Citation Format: Perrine Martin-Jeantet, Siham Hedir, Fabiane Sonego, Gaëlle Martin, Yacine Cherifi, Kader Thiam. Tumor cell line-derived xenograft subtype shapes tumor microenvironment composition in BRGSF-HIS mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1530.

Abstract 1362: IOMX-0675, a LILRB1 and LILRB2 cross-specific antibody, effectively repolarizes immunosuppressive myeloid cells and activates T cells leading to potent tumor cell killing

Abstract Recently, myeloid checkpoints in the tumor microenvironment have gained increased attention in the context of tumor immune evasion. LILRB1 (ILT2) and LILRB2 (ILT4) are immunosuppressive receptors of the leukocyte immunoglobulin-like receptor (LILR) family that recognize both classical and non-classical MHC-I molecules (e.g., HLA-G). While tumor-infiltrating myeloid cells express both LILRB1 and LILRB2, lymphoid cells are restricted to LILRB1 expression. LILRB1 and LILRB2 are frequently co-expressed with immune-activating LILR family members LILRA1 and LILRA3 in several tumor indications and upregulated in patients non-responsive to T cell checkpoint blockade. Furthermore, the non-classical MHC-I molecule HLA-G, a major ligand of LILRB1 and LILRB2 in the tumor environment, is overexpressed and associated with poor prognosis in multiple solid cancer types. IOMX-0675, a fully human, Fc-silenced, monoclonal immunoglobulin G1 (IgG1) antibody with a highly differentiated binding profile, that binds selectively with high affinity to the inhibitory receptors LILRB1 and LILRB2, while binding only weakly to the closely related immune-activating LILR family members LILRA1 and LILRA3, was identified from iOmx’ proprietary phage display library. A high-resolution Fab-based Octet assay was established to monitor the IOMX-0675-mediated blocking of LILRB1 or LILRB2 binding to HLA-G. The LILRB1/2 cross-specific antibody promotes phagocytic and pro-inflammatory activity of various macrophage subtypes, which was monitored by flow cytometry and cytokine profiling. In co-cultures of monocyte-derived macrophages with autologous T cells, IOMX-0675 shows high potential to reprogram dose-dependently immunosuppressive macrophage, to further activate pro-inflammatory macrophage subtypes and thereby rescues the activity of the lymphoid immune compartment. Even in environments dominated by LILRA1/A3, IOMX-0675 shows a strong binding capacity to the immunosuppressive LILRB1/B2 receptors and significantly repolarizes the immune environment. In summary, we discovered IOMX-0675, a cross-specific antibody antagonizing both LILRB1 and LILRB2 with high selectivity, that exhibits potent reprogramming of the immunosuppressive myeloid compartment and restores cytotoxic T cell activity in the tumor microenvironment. Negligible binding to immune-activating LILR family members by IOMX-0675 could unleash full anti-tumor activity. The differential binding profile of IOMX-0675 provides best-in-class potential and may maximize anti-tumor efficacy for the benefit of patients with high-unmet medical need, who are resistant to T cell checkpoint blockade. Citation Format: Christina Hartl, Jonas Zantow, Ilona-Petra Maser, Marisa Stebegg-Wagner, Simone Friedrich, Jonas Schilz, Stefan Kaden, Ronny Milde, Eugenia Korotkova, Michail Maraslis, Bettina Langer, Michal Swiat, Carmen Ginzel, Carmen Ammerhauser, Lucille Albert, Leonie Majunke, Alina Huth, Kritika Sudan, Murray Yule, Christine Rothe, Hannes Loferer, Maximilian Aigner, Alexander N. Marziale, Stefan Bissinger. IOMX-0675, a LILRB1 and LILRB2 cross-specific antibody, effectively repolarizes immunosuppressive myeloid cells and activates T cells leading to potent tumor cell killing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1362.

Deletion of IL-27p28 induces CD8 T cell immunity against colorectal tumorigenesis

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, characterized by molecular and clinical heterogeneity. Interleukin (IL)-27, a heterodimeric cytokine composed of p28 and EBI3 subunits, has been reported to exert potent antitumor activity in several cancer models. However, the precise role of IL-27 in the pathogenesis of CRC remains unclear. Here, we show that during the azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC development, IL-27p28 levels are dramatically increased in peripheral blood and tumor tissues, and the cytokine is mainly produced by tumor-infiltrating myeloid cells. IL-27p28 deficient mice display tumor resistances in both inflammation-associated CRC model and syngeneic MC38 colon cancer model. Administration with IL-27p28 neutralizing antibody also reduces the tumor formation in AOM/DSS-treated mice. Mechanically, CD8+ T cells in IL-27p28-/- mice exhibit enhanced tumor infiltration and cytotoxicity, which can be largely attributed to activation of the Akt/mTOR signaling pathway. Furthermore, selective depletion of CD8+ T cells in IL-27p28-/- mice markedly accelerate tumor growth and almost abrogate the protective effects of IL-27p28 deficiency. Most interestingly, the expression of IL-27p28 is also upregulated in tumor tissues of CRC patients and those with high expression of IL-27p28 tend to have a poorer overall survival. Our results suggest that loss of IL-27p28 suppresses colorectal tumorigenesis by augmenting CD8+ T cell-mediated anti-tumor immunity. Targeting IL-27p28 could be developed as a novel strategy for the treatment of colorectal cancers.

Single-cell RNA-seq analyses inform necroptosis-associated myeloid lineages influence the immune landscape of pancreas cancer.

Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties in pancreatic ductal adenocarcinoma (PDAC) remain elusive. In this study, we conducted scRNA-seq data analysis of cells from 12 primary tumor (PT) tissues, 4 metastatic (Met) tumor tissues, 3 adjacent normal pancreas tissues (Para), and PBMC samples across 16 PDAC patients, and revealed a heterogeneous TIMs environment in PDAC. Systematic comparisons between tumor and non-tumor samples of myeloid lineages identified 10 necroptosis-associated genes upregulated in PDAC tumors compared to 5 upregulated in paratumor or healthy peripheral blood. A novel RTM (resident tissue macrophages), GLUL-SQSTM1- RTM, was found to act as a positive regulator of immunity. Additionally, HSP90AA1+HSP90AB1+ mast cells exhibited pro-immune characteristics, and JAK3+TLR4+ CD16 monocytes were found to be anti-immune. The findings were validated through clinical outcomes and cytokines analyses. Lastly, intercellular network reconstruction supported the associations between the identified novel clusters, cancer cells, and immune cell populations. Our analysis comprehensively characterized major myeloid cell lineages and identified three subsets of myeloid-derived cells associated with necroptosis. These findings not only provide a valuable resource for understanding the multi-dimensional characterization of the tumor microenvironment in PDAC but also offer valuable mechanistic insights that can guide the design of effective immuno-oncology treatment strategies.

Abstract B048: Multiplex analysis of pancreatic, oesophageal and rectal adenocarcinoma: A cross-cancer approach on the impact of neoadjuvant therapy on the tumour microenvironment

Abstract Introduction: The prognosis of gastrointestinal malignancies has improved significantly with the introduction of neoadjuvant therapy (neoTx). For rectal (RCa) and esophageal adenocarcinoma (OCa), neoTx has become the standard of care, resulting in tumor-downsizing and significantly prolonged patient survival. However, the effects of neoTx on the topographical interactions between different populations of tumor-infiltrating immune cells, the degree of intratumoral immune infiltration, the distance to tumor cells, as well as their spatial interactions with other important features of the tumor microenvironment (TME), are still unknown. In this cross-cancer histopathological profiling of the microenvironment of rectal and esophageal tumors, we aim to investigate the local effects of cytotoxic agents and determine whether these correspond to the pathological changes observed in pancreatic cancer (PCa). Methods In this study, we employed multiplex immunohistochemistry (mIHC) based on tyramide signal amplification (TSA) using OPAL® dyes and a customized 6-plex approach to characterize tumor-associated stromal features (CD11c, CD34, NCAM, PGP9.5, aSMA, PanCK) as well as tumor-infiltrating lymphoid (CD3, CD4, CD8, CD20, FOXP3, PanCK) and myeloid cell subsets (CD11b, CD33, CD68, CD208, HLA-DR, PanCK). FFPE samples from 60 neoadjuvantly treated RCa and 40 OCa patients and a matched cohort of primary resected patients were included in the analysis. Results In PCa, neoTx alters the TME by depleting pro-tumorigenic immune cells, such as myeloid-derived suppressor cells (MDSC) and regulatory T cells, and suppressing tumor-associated stromal activation, neural invasion, and microangiogenesis. In our current study, we generated three standardized 6-plex panels for comprehensive histopathologic analysis of the immune architecture and associated stromal features of neoadjuvantly treated RCa and OCa patients compared with primary resected patients. Lymphoid subpopulations included Th-cells, cytotoxic T-cells, regulatory T-cells, and B-cells, while MDSC, dendritic cells, M1- and M2-macrophages were analyzed in the myeloid panel within the same FFPE slide. Conclusion: Our findings highlight new differential cell identities in neoTx-treated PCa patients and confirm their suitability for optimizing future clinical immunotherapy trials. Our current approach validates multiplex-IHC approaches for histological profiling of FFPE tumor samples in RCa and OCa and demonstrates the importance of a deep topographic characterization to understand the TME composition of gastrointestinal malignancies after neoTx. Citation Format: Leonard Richter. Multiplex analysis of pancreatic, oesophageal and rectal adenocarcinoma: A cross-cancer approach on the impact of neoadjuvant therapy on the tumour microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B048.

Activation of endogenous glucocorticoids by HSD11B1 inhibits the antitumor immune response in renal cancer

ABSTRACT Although immune-based therapies have revolutionized the management of cancer, novel approaches are urgently needed to improve their outcome. We investigated the role of endogenous steroids in the resistance to cancer immunotherapy, as these have strong immunomodulatory functions. Using a publicly available database, we found that the intratumoral expression of 11 beta-hydroxysteroid dehydrogenase type 1 (HSD11B1), which regenerates inactive glucocorticoids into active glucocorticoids, was associated with poor clinical outcome and correlated with immunosuppressive gene signatures in patients with renal cell carcinoma (RCC). HSD11B1 was mainly expressed in tumor-infiltrating immune myeloid cells as seen by immunohistochemistry in RCC patient samples. Using peripheral blood mononuclear cells from healthy donors or immune cells isolated from the tumor of RCC patients, we showed that the pharmacological inhibition of HSD11B1 improved the response to the immune checkpoint inhibitor anti-PD-1. In a subcutaneous mouse model of renal cancer, the combination of an HSD11B1 inhibitor with anti-PD-1 treatment increased the proportion of tumor-infiltrating dendritic cells. In an intrarenal mouse tumor model, HSD11B1 inhibition increased the survival of mice treated with anti-PD-1. In addition, inhibition of HSD11B1 sensitized renal tumors in mice to immunotherapy with resiquimod, a Toll-like receptor 7 agonist. Mechanistically, we demonstrated that HSD11B1 inhibition combined with resiquimod increased T cell-mediated cytotoxicity to tumor cells by stimulating the antigen-presenting capacity of dendritic cells. In conclusion, these results support the use of HSD11B1 inhibitors to improve the outcome of immunotherapy in renal cancer and highlight the role of the endogenous glucocorticoid metabolism in the efficacy of immunotherapy.

Single-cell analyses revealed key tumor-infiltrating myeloid cell subsets associated with clinical outcomes in different subtypes of breast cancer

Single-cell analyses revealed key tumor-infiltrating myeloid cell subsets associated with clinical outcomes in different subtypes of breast cancer

Inducible nitric oxide synthase (iNOS)-activated Cxcr2 signaling in myeloid cells promotes TGFβ-dependent squamous cell carcinoma lung metastasis

Transforming growth factor beta (TGFβ) activity is linked to metastasis in many cancer types, but whether TGFβ activity is necessary for squamous cell carcinoma (SCC) lung metastasis has not been studied. Here we used a lung metastatic SCC model derived from keratin 15 (K15). KrasG12D.Smad4−/− SCC and human SCC specimens to identify metastasis drivers and test therapeutic interventions. We demonstrated that a TGFβ receptor (TGFβR) inhibitor reduced lung metastasis in mouse SCC correlating with reduced CD11b+/Ly6G+ myeloid cells positive for inducible nitric oxide synthase (iNOS). Further, TGFβ activity and iNOS were higher in primary human oral SCCs with metastasis than SCCs without metastasis. Consistently, either depleting myeloid cells with anti-Gr1 antibody or inhibiting iNOS with L-N6-(1-iminoethyl)-l-lysine (L-NIL) reduced SCC lung metastasis. L-NIL treated tumor-bearing mice exhibited reductions in tumor-infiltrating myeloid cells and in plasma Cxcl5 levels, and attenuated primary tumor growth with increased apoptosis and decreased proliferation. Blocking Cxcl5 with an antagonist of its receptor Cxcr2, SB225002, also reduced SCC lung metastasis.

Interactions between MFAP5 + fibroblasts and tumor-infiltrating myeloid cells shape the malignant microenvironment of colorectal cancer

BackgroundThe therapeutic targeting of the tumor microenvironment (TME) in colorectal cancer (CRC) has not yet been fully developed and utilized because of the complexity of the cell–cell interactions within the TME. The further exploration of these interactions among tumor-specific clusters would provide more detailed information about these communication networks with potential curative value.MethodsSingle-cell RNA sequencing, spatial transcriptomics, and bulk RNA sequencing datasets were integrated in this study to explore the biological properties of MFAP5 + fibroblasts and their interactions with tumor-infiltrating myeloid cells in colorectal cancer. Immunohistochemistry and multiplex immunohistochemistry were performed to confirm the results of these analyses.ResultsWe profiled heterogeneous single-cell landscapes across 27,414 cells obtained from tumors and adjacent tissues. We mainly focused on the pro-tumorigenic functions of the identified MFAP5 + fibroblasts. We demonstrated that tumor-resident MFAP5 + fibroblasts and myeloid cells (particularly C1QC + macrophages) were positively correlated in both spatial transcriptomics and bulk RNA-seq public cohorts. These cells and their interactions might shape the malignant behavior of CRC. Intercellular interaction analysis suggested that MFAP5 + fibroblasts could reciprocally communicate with C1QC + macrophages and other myeloid cells to remodel unfavorable conditions via MIF/CD74, IL34/CSF1R, and other tumor-promoting signaling pathways.ConclusionOur study has elucidated the underlying pro-tumor mechanisms of tumor-resident MFAP5 + fibroblasts and provided valuable targets for the disruption of their properties.

Abstract IA020: Senescence in cancer and myeloid cells control prostate cancer progression

Abstract Recent evidence demonstrates that senescence can act as a tumor-suppressive or tumor-promoting mechanism in cancer. Here, I will discuss recent findings demonstrating that cellular senescence can promote metastases formation in prostate cancer and that therapies that eliminate senescent tumor cells (senolytics) or reprogram the SASP (senostatics) can efficiently prevent metastases in different mouse models. Moreover, I will present recent data demonstrating that senescence can occur in tumor-infiltrating myeloid cells (PMN-MDSCs). As previously reported, this population of immune cells can support prostate tumor proliferation through different mechanisms. Senescent-like myeloid cells express TREM2, are more immunosuppressive and tumor-promoting, and have an increased lifespan than canonical PMN-MDSCs. Genetic and pharmacological elimination of senescent-like myeloid cells decreases tumor progression in different mouse models of prostate cancer. These results support the development of senolytics targeting cancer and senescent-like myeloid cells for cancer therapy. Citation Format: Andrea Alimonti. Senescence in cancer and myeloid cells control prostate cancer progression [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr IA020.

Single-cell RNA sequencing and influences of necroptosis-associated myeloid lineages in immune microenvironment of PDAC.

e16261 Background: Tumor-infiltrating myeloid cells (TIMs) are abundant in tumor stroma and emerging evidence indicate that the presence of these cells influences clinical outcomes in many cancer types. TIMs play important roles in tumor progression and specific subsets may exhibit divergent anti-tumor or tumor-promoting functions. Currently, the molecular characteristics of TIMs in pancreatic ductal adenocarcinoma (PDAC) largely remain unknown. Like other programmed cell death procedures such as ferroptosis and pyroptosis, necroptosis has recently emerged as an important cellular event that modulates tumorigenesis and tumor progression. Combination of necroptosis and TIMs is of great interest to study the molecular mechanism of clinical outcomes for PDAC patients. Methods: This study enrolled 16 PDAC patients. The scRNA-seq data were obtained from a published dataset and each patient included primary tumor, metastatic tumor, primary tumor-adjacent and PBMC samples. All myeloid cells comprising granulocytes, monocytes, macrophages, and dendritic cells from enrolled patients were extracted for further analysis. We performed comprehensive analysis about the characteristics of myeloid lineages, differentially expressed genes, pathway enrichment analysis and novel cell subtype identification. The necroptosis-associated novel TIMs cell sub-clusters were elucidated in detail. Results: To comprehensively analyze the heterogeneous TIMs microenvironment in PDAC patients using scRNA-seq dataset, we firstly obtained consistently upregulated genes among granulocytes, monocytes, macrophages, and dendritic cell types between tumor samples and non-tumor samples. Those uniquely expressed genes represent different functions in necroptosis-associated TIMs cells. In total, we identified 10 necroptosis-associated upregulated genes in PDAC tumors and 5 upregulated genes in tumor-adjacent and peripheral blood samples, respectively. Based on the cells expressed those necroptosis-related genes, we identified three novel cell populations, including GLUL-SQSTM1- RTM, HSP90AA1+HSP90AB1+ mast cells, and JAK3+TLR4+ CD16 monocytes, which were regulators of immunity either tumor-promoters or tumor-suppressors. Clinical outcomes further supported their function roles in the PDAC tumor microenvironment. Conclusions: This study comprehensively studied the heterogeneity of myeloid microenvironment in PDAC by scRNA-Seq. Several necroptosis-associated genes and myeloid cell sub-clusters were identified and they have prognostic clinical values in PDAC. These preliminary results were helpful for further understanding the molecular mechanism of PDAC treatment strategies.

A phase (Ph) I/II trial of abiraterone acetate in combination with tildrakizumab (anti-IL23 monoclonal antibody) in patients with metastatic castration-resistant prostate cancer (mCRPC).

TPS5105 Background: Tumor-infiltrating inflammatory myeloid cells promote prostate cancer (PC) growth and therapeutic resistance. Myeloid inflammatory cells release interleukin-23 (IL-23) to fuel tumor growth via JAK2-STAT3 signalling and facilitate tumor-promoting T helper 17 (TH17) differentiation in PC models in vivo. IL-23 blockade reverses resistance to AR-targeting in vivo; we hypothesise that targeting IL-23 can be an effective therapeutic strategy for CRPC. Tildrakizumab, an anti-IL-23 (p19) monoclonal antibody, is FDA/EMA approved for treating moderate-severe psoriasis. In progress is the first clinical trial to combining IL-23 and AR signalling blockade in humans. Methods: This is an open-label, single-arm, Ph 1/2, dose-escalation and expansion study evaluating safety and tolerability of tildrakizumab and abiraterone acetate combination therapy in patients with mCRPC. Eligible patients must have progressed on androgen deprivation therapy, plus abiraterone and/or enzalutamide. The Ph 1 trial will adopt a one-stage Bayesian Continual Reassessment Method design exploring escalating doses of 4-weekly, IV tildrakizumab (100 mg, 300 mg, and 600 mg), in combination with standard fixed doses of abiraterone acetate and methylprednisolone, with the aim of determining the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Depending on the number of responses observed, tolerable dose levels may be expanded up to 10 patients after review by the Safety Review Committee (SRC). The RP2D and MTD determination will be based on the rate of toxicity and efficacy, reviewed by the SRC. Once RP2D is determined, the Ph 2 study will enrol up to 25 response-evaluable patients using a Simon’s two-stage design. Primary endpoint of the Ph 2 trial is overall response rate. Adverse events are assessed according to CTCAE v5. Tumor response is determined according to RECIST v1.1, confirmed PSA decline of at least 50%, and/or CTC conversion. PK analyses is being performed for both drugs to identify potential drug-drug interactions. PD analyses is being performed on archival and serial tumour biopsies and blood samples to investigate putative predictive biomarkers and confirm on-target and downstream effector modulation. The trial began enrolling in January 2021 in the United Kingdom and Switzerland. As of January 22th 2023, 12 patients were included in the study. Clinical trial information: NCT04458311 .

Single-cell RNA sequencing reveals heterogeneous immune landscape of tumor-infiltrating lymphocytes in the glioblastoma tumor microenvironment in the absence of IFNAR

Abstract Glioblastoma (GBM) is known to be the most common malignant brain cancer with a very poor prognosis. Despite standard conventional therapies patient survival rates still remain poor and reasons for this may be due to the extensive tumor cellular heterogeneity of the tumor microenvironment. Type I interferons (IFNs) are a family of cytokines produced by multiple cell types and are known to play a role in anticancer immunity through their signaling via the interferon alpha receptor (IFNAR). We find that absence of IFNAR compromises anti-tumor immunity against GBM. Single-cell RNA analysis of the immune landscape of GBM tumor-bearing IfnαR−/−mice reveals that there is an overall decrease in tumor-infiltrating lymphocytes into the brain along with overall decreased expression of IFNγ, TNFα, and Granzyme A. Analysis of lymphoid cells including T cells and NK cells shows substantial decreased infiltration in the presence of GBM in IFNαR deficient mice. Notably, CD4 and CD8 T cell infiltration is considerably reduced, although how the functions of these cells are affected is yet unknown. Analysis of tumor-infiltrating myeloid cells in the absence of interferon signaling reveals decreased infiltration of monocytes and tumor-associated macrophages as well. Thus, in this study, we are able to see that the absence of type I interferon signaling affects the overall recruitment of lymphoid and myeloid cells during the progression of GBM and likely contributes to the exacerbation of anti-tumor immunity.