GM-CSF drives myelopoiesis, recruitment and polarisation of tumour-associated macrophages in cholangiocarcinoma and systemic blockade facilitates antitumour immunity

Granulocyte macrophage colony stimulating factor in virus-host interactions and its implication for immunotherapy

Viruses have evolved to strategically exploit cellular signaling pathways to evade host immune defenses. GM-CSF signaling plays a pivotal role in regulating inflammation, activating myeloid cells, and enhancing the immune response to infections. Due to its central role in the immune system, viruses may target this pathway to further establish infection. This review focuses on key studies elucidating virus interactions with GM-CSF signaling proteins and summarizes findings on the impact of viral infections on GM-CSF production. Additionally, therapeutic strategies centered around GM-CSF are investigated, such as the potential benefits of administering GM-CSF versus inhibiting GM-CSF signaling to mitigate viral-induced aberrant inflammation. Understanding these virus-host interactions provides valuable insights that help further our understanding to develop future therapeutic approaches in modulating the immune response during viral infections.

New Relevant Evidence in Cholangiocarcinoma Biology and Characterization

Among solid tumors, cholangiocarcinoma (CCA) emerges as one of the most difficult to eradicate. The silent and asymptomatic nature of this tumor, particularly in its early stages, as well as the high heterogeneity at genomic, epigenetic, and molecular levels delay the diagnosis, significantly compromising the efficacy of current therapeutic options and thus contributing to a dismal prognosis. Extensive research has been conducted on the molecular pathobiology of CCA, and recent advances have been made in the classification and characterization of new molecular targets. Both targeted therapy and immunotherapy have emerged as effective and safe strategies for various types of cancers, demonstrating potential benefits in advanced CCA. Furthermore, the deeper comprehension of the cellular and molecular components in the tumor microenvironment (TME) has opened up possibilities for new innovative treatment methods. This review discusses recent evidence in the characterization and molecular biology of CCA, highlighting novel possible druggable targets.

Immunobiology of biliary tract cancer and recent clinical findings in approved and upcoming immune checkpoint inhibitors

INTRODUCTION

Recently, immunotherapy has offered new hope for treating biliary tract cancer (BTC). However, several issues are to be considered, including the lack of validated predictive biomarkers that could help to identify patient groups which are most likely to benefit from such therapeutic approaches.

AREAS COVERED

In the current article, we will provide an overview of recent results and ongoing and future research directions of immunotherapy in BTC, with a special focus on recently published, practice-changing data, and ongoing active and recruiting clinical trials.

EXPERT OPINION

At this moment, dozens of clinical trials in phases I to III are evaluating the role of cancer immunotherapy in this setting, with the hope of adding more therapeutic options for BTC patients. Future research must focus on the development of novel agents and combinations, but the validation of biomarkers remains an urgent need. As more research results emerge, novel combinatorial strategies are destined to further transform the treatment paradigm for this heterogeneous and aggressive tumor type.

Cancer cell - Fibroblast crosstalk via HB-EGF, EGFR, and MAPK signaling promotes the expression of macrophage chemo-attractants in squamous cell carcinoma

Interactions between cells in the tumor microenvironment (TME) shape cancer progression and patient prognosis. To gain insights into how the TME influences cancer outcomes, we derive gene expression signatures indicative of signaling between stromal fibroblasts and cancer cells, and demonstrate their prognostic significance in multiple and independent squamous cell carcinoma cohorts. By leveraging information within the signatures, we discover that the HB-EGF/EGFR/MAPK axis represents a hub of tumor-stroma crosstalk, promoting the expression of CSF2 and LIF and favoring the recruitment of macrophages. Together, these analyses demonstrate the utility of our approach for interrogating the extent and consequences of TME crosstalk.

Tumor-associated macrophages: orchestrators of cholangiocarcinoma progression

Cholangiocarcinoma (CCA) is a rare but highly invasive cancer, with its incidence rising in recent years. Currently, surgery remains the most definitive therapeutic option for CCA. However, similar to other malignancies, most CCA patients are not eligible for surgical intervention at the time of diagnosis. The chemotherapeutic regimen of gemcitabine combined with cisplatin is the standard treatment for advanced CCA, but its effectiveness is often hampered by therapeutic resistance. Recent research highlights the remarkable plasticity of tumor-associated macrophages (TAMs) within the tumor microenvironment (TME). TAMs play a crucial dual role in either promoting or suppressing tumor development, depending on the factors that polarize them toward pro-tumorigenic or anti-tumorigenic phenotypes, as well as their interactions with cancer cells and other stromal components. In this review, we critically examine recent studies on TAMs in CCA, detailing the expression patterns and prognostic significance of different TAM subtypes in CCA, the mechanisms by which TAMs influence CCA progression and immune evasion, and the potential for reprogramming TAMs to enhance anticancer therapies. This review aims to provide a framework for deeper future research.

oHSV2-mGM repolarizes TAMs and cooperates with αPD1 to reprogram the immune microenvironment of residual cancer after radiofrequency ablation

BACKGROUND

Due to the size and location of the tumor, incomplete radiofrequency ablation (iRFA) of the target tumor inhibits tumor immunity. In this study, a murine herpes simplex virus (oHSV2-mGM) armed with granulocyte-macrophage colony-stimulating factor (GM-CSF) was constructed to explore its effect on innate and adaptive immunity during iRFA, and the inhibitory effect of programmed cell death-1 (PD1) on tumor.

METHODS

We verified the polarization and activation of RAW264.7 cells mediated by oHSV2-mGM in vitro. Subsequently, we evaluated the efficacy of oHSV2-mGM alone and in combination with αPD1 in the treatment of residual tumors after iRFA in two mouse models. RNA-seq was used to characterize the changes of tumor microenvironment.

RESULTS

oHSV2-mGM lysate effectively stimulated RAW264.7 cells to polarize into M1 cells and activated M1 phenotypic function. In the macrophage clearance experiment, oHSV2-mGM activated the immune response of tumor in mice. The results in vivo showed that oHSV2-mGM showed better anti-tumor effect in several mouse tumor models. Finally, oHSV2-mGM combined with PD1 antibody can further enhance the anti-tumor effect of oHSV2-mGM and improve the complete remission rate of tumor in mice.

CONCLUSION

The application of oHSV2-mGM leads to the profound remodeling of the immune microenvironment of residual tumors. oHSV2-mGM also works in synergy with PD1 antibody to achieve complete remission of tumors that do not respond well to monotherapy at immune checkpoints. Our results support the feasibility of recombinant oncolytic virus in the treatment of residual tumors after iRFA, and propose a new strategy for oncolytic virus treatment of tumors.

Recent Advances in Immunotherapy for Advanced Biliary Tract Cancer

OPINION STATEMENT

Biliary tract cancer (BTC) is a heterogeneous group of aggressive malignancies that arise from the epithelium of the biliary tract. Most patients present with locally advanced or metastatic disease at the time of diagnosis. For patients with unresectable BTC, the survival advantage provided by systemic chemotherapy was limited. Over the last decade, immunotherapy has significantly improved the therapeutic landscape of solid tumors. There is an increasing number of studies evaluating the application of immunotherapy in BTC, including immune checkpoint inhibitors (ICIs), cancer vaccines and adoptive cell therapy. The limited response to ICIs monotherapy in unselected patients prompted investigators to explore different combination therapy strategies. Early clinical trials of therapeutic cancer vaccination and adoptive cell therapy have shown encouraging clinical results. However, there still has been a long way to go via validation of therapeutic efficacy and exploration of strategies to increase the efficacy. Identifying biomarkers that predict the response to immunotherapy will allow a more accurate selection of candidates. This review will provide an up-to-date overview of the current clinical data on the role of immunotherapy, summarize the promising biomarkers predictive of the response to ICIs and discuss the perspective for future research direction of immunotherapy in advanced BTC.

Pan-lysyl oxidase inhibition disrupts fibroinflammatory tumor stroma, rendering cholangiocarcinoma susceptible to chemotherapy

BACKGROUND

Cholangiocarcinoma (CCA) features highly desmoplastic stroma that promotes structural and functional resistance to therapy. Lysyl oxidases (LOX, LOXL1-4) catalyze collagen cross-linking, thereby increasing stromal rigidity and facilitating therapeutic resistance. Here, we evaluate the role of lysyl oxidases in stromal desmoplasia and the effects of pan-lysyl oxidase (pan-LOX) inhibition in CCA.

METHODS

Resected CCA and normal liver specimens were analyzed from archival tissues. Spontaneous and orthotopic murine models of intrahepatic CCA (iCCA) were used to assess the impact of the pan-LOX inhibitor PXS-5505 in treatment and correlative studies. The functional role of pan-LOX inhibition was interrogated through in vivo and ex vivo assays.

RESULTS

All 5 lysyl oxidases are upregulated in CCA and reduced lysyl oxidase expression is correlated with an improved prognosis in resected patients with CCA. Spontaneous and orthotopic murine models of intrahepatic cholangiocarcinoma upregulate all 5 lysyl oxidase isoforms. Pan-LOX inhibition reversed mechanical compression of tumor vasculature, resulting in improved chemotherapeutic penetrance and cytotoxic efficacy. The combination of chemotherapy with pan-LOX inhibition increased damage-associated molecular pattern release, which was associated with improved antitumor T-cell responses. Pan-LOX inhibition downregulated macrophage invasive signatures in vitro, rendering tumor-associated macrophages more susceptible to chemotherapy. Mice bearing orthotopic and spontaneously occurring intrahepatic cholangiocarcinoma tumors exhibited delayed tumor growth and improved survival following a combination of pan-LOX inhibition with chemotherapy.

CONCLUSIONS

CCA upregulates all 5 lysyl oxidase isoforms, and pan-LOX inhibition reverses tumor-induced mechanical forces associated with chemotherapy resistance to improve chemotherapeutic efficacy and reprogram antitumor immune responses. Thus, combination therapy with pan-LOX inhibition represents an innovative therapeutic strategy in CCA.

Recent Advances in Nanoimmunotherapy by Modulating Tumor-Associated Macrophages for Cancer Therapy

Cancer immunotherapy has yielded remarkable results across a variety of tumor types. Nevertheless, the complex and immunosuppressive microenvironment within solid tumors poses significant challenges to established therapies such as immune checkpoint blockade (ICB) and chimeric antigen receptor T-cell (CAR-T) therapy. Within the milieu, tumor-associated macrophages (TAMs) play a significant role by directly suppressing T-cell functionality and fostering an immunosuppressive environment. Effective regulation of TAMs is, therefore, crucial to enhancing the efficacy of immunotherapies. Various therapeutic strategies targeting TAM modulation have emerged, including blocking TAM recruitment, direct elimination, promoting repolarization toward the M1 phenotype, and enhancing phagocytic capacity against tumor cells. The recently introduced CAR macrophage (CAR-M) therapy opens new possibilities for macrophage-based immunotherapy. Compared with CAR-T, CAR-M may demonstrate superior targeting and infiltration capabilities toward solid tumors. This review predominantly delves into the origin and development process of TAMs, their role in promoting tumor growth, and provides a comprehensive overview of immunotherapies targeting TAMs. It underscores the significance of regulating TAMs in bolstering antitumor therapies while discussing the potential and challenges of developing TAMs as targets for immunotherapy.

Enzymatic depletion of circulating glutamine is immunosuppressive in cancers

Although glutamine addiction in cancer cells is extensively reported, there is controversy on the impact of glutamine metabolism on the immune cells within the tumor microenvironment (TME). To address the role of extracellular glutamine, we enzymatically depleted circulating glutamine using PEGylated Helicobacter pylori gamma-glutamyl transferase (PEG-GGT) in syngeneic mouse models of breast and colon cancers. PEG-GGT treatment inhibits growth of cancer cells in vitro, but in vivo it increases myeloid-derived suppressor cells (MDSCs) and has no significant impact on tumor growth. By deriving a glutamine depletion signature, we analyze diverse human cancers within the TCGA and illustrate that glutamine depletion is not associated with favorable clinical outcomes and correlates with accumulation of MDSC. Broadly, our results help clarify the integrated impact of glutamine depletion within the TME and advance PEG-GGT as an enzymatic tool for the systemic and selective depletion (no asparaginase activity) of circulating glutamine in live animals.

Deciphering the performance of macrophages in tumour microenvironment: a call for precision immunotherapy

Macrophages infiltrating tumour tissues or residing in the microenvironment of solid tumours are known as tumour-associated macrophages (TAMs). These specialized immune cells play crucial roles in tumour growth, angiogenesis, immune regulation, metastasis, and chemoresistance. TAMs encompass various subpopulations, primarily classified into M1 and M2 subtypes based on their differentiation and activities. M1 macrophages, characterized by a pro-inflammatory phenotype, exert anti-tumoural effects, while M2 macrophages, with an anti-inflammatory phenotype, function as protumoural regulators. These highly versatile cells respond to stimuli from tumour cells and other constituents within the tumour microenvironment (TME), such as growth factors, cytokines, chemokines, and enzymes. These stimuli induce their polarization towards one phenotype or another, leading to complex interactions with TME components and influencing both pro-tumour and anti-tumour processes.This review comprehensively and deeply covers the literature on macrophages, their origin and function as well as the intricate interplay between macrophages and the TME, influencing the dual nature of TAMs in promoting both pro- and anti-tumour processes. Moreover, the review delves into the primary pathways implicated in macrophage polarization, examining the diverse stimuli that regulate this process. These stimuli play a crucial role in shaping the phenotype and functions of macrophages. In addition, the advantages and limitations of current macrophage based clinical interventions are reviewed, including enhancing TAM phagocytosis, inducing TAM exhaustion, inhibiting TAM recruitment, and polarizing TAMs towards an M1-like phenotype. In conclusion, while the treatment strategies targeting macrophages in precision medicine show promise, overcoming several obstacles is still necessary to achieve an accessible and efficient immunotherapy.

Syngeneic murine models with distinct immune microenvironments represent subsets of human intrahepatic cholangiocarcinoma

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a poorly immunogenic malignancy associated with limited survival. Syngeneic immunocompetent mouse models of CCA are an essential tool to elucidate the tumor immune microenvironment (TIME), understand mechanisms of tumor immune evasion, and test novel immunotherapeutic strategies. The scope of this study was to develop and characterize immunocompetent CCA models with distinct genetic drivers, and correlate tumor genomics, immunobiology, and therapeutic response.

METHODS

A multifaceted approach including scRNA-seq, CITE-seq, whole exome and bulk RNA sequencing was employed. FDA-approved PD-1/PD-L1 antibodies were tested in humanized PD-1/PD-L1 mice (HuPD-H1).

RESULTS

A genetic mouse model of intrahepatic CCA (iCCA) driven by intrabiliary transduction of Fbxw7ΔF/Akt that mimics human iCCA was generated. From the Fbxw7ΔF/Akt tumors, a murine cell line (FAC) and syngeneic model with genetic and phenotypic characteristics of human iCCA were developed. Established SB1 (YAPS127A/Akt) and KPPC (KrasG12Dp53L/L) models were compared to the FAC model. Although the models had transcriptomic similarities, they had substantial differences as well. Mutation patterns of FAC, SB1, and KPPC cells matched different mutational signatures in Western and Japanese CCA patient cohorts. KPPC tumors had a high tumor mutation burden. FAC tumors had a T cell-infiltrated TIME, while SB1 tumors had a preponderance of suppressive myeloid cells. FAC, SB1, and KPPC tumors matched different immune signatures in human iCCA cohorts. Moreover, FAC, SB1, and KPPC tumor-bearing HuPD-H1 mice displayed differential responses to nivolumab or durvalumab.

CONCLUSIONS

Syngeneic iCCA models display a correlation between tumor genotype and TIME phenotype, with differential responses to FDA-approved immunotherapies. This study underscores the importance of leveraging multiple preclinical models to understand responses to immunotherapy in different genetic subsets of human CCA.

IMPACT AND IMPLICATIONS

Understanding the relationship between tumor genotype and the phenotype of the immune microenvironment is an unmet need in cholangiocarcinoma (CCA). Herein, we use syngeneic murine models of intrahepatic CCA with different genetic drivers to demonstrate a correlation between tumor genotype and immune microenvironment phenotype in murine models, which is associated with differential responses to FDA-approved immunotherapies. This information will help guide other preclinical studies. Additionally, it emphasizes that immune checkpoint inhibition in patients with CCA is not a "one-size-fits-all" approach. Our observations suggest that, as for targeted therapies, patients should be stratified and selected for treatment according to their tumor genetics.

Neoadjuvant immunotherapy based on PD-1/L1 inhibitors for gastrointestinal tumors: a review of the rationale and clinical advances

The landscape of current tumor treatment has been revolutionized by the advent of immunotherapy based on PD-1/PD-L1 inhibitors. Leveraging its capacity to mobilize systemic antitumor immunity, which is primarily mediated by T cells, there is growing exploration and expansion of its potential value in various stages of clinical tumor treatment. Neoadjuvant immunotherapy induces a robust immune response against tumors prior to surgery, effectively facilitating tumor volume reduction, early eradication or suppression of tumor cell activity, and control of potential metastatic spread, to improve curative surgical resection rates, and prevent tumor recurrence. This review delineates the theoretical basis of neoadjuvant immunotherapy from preclinical research evidence, discusses specific challenges in clinical application, and provides a comprehensive overview of clinical research progress in neoadjuvant immunotherapy for gastrointestinal tumors. These findings suggest that neoadjuvant immunotherapy has the potential to ameliorate immunosuppressive states and enhance cytotoxic T cell function while preserving lymphatic drainage in the preoperative period. However, further investigations are needed on specific treatment regimens, suitable patient populations, and measurable endpoints. Despite numerous studies demonstrating the promising efficacy and manageable adverse events of neoadjuvant immunotherapy in gastrointestinal tumors, the availability of high-quality randomized controlled trials is limited, which highlights the necessity for further research.

Genetic/Epigenetic Alteration and Tumor Immune Microenvironment in Intrahepatic Cholangiocarcinoma: Transforming the Immune Microenvironment with Molecular-Targeted Agents

Background

Intrahepatic cholangiocarcinoma (iCCA) is often diagnosed at an advanced stage, leading to limited treatment options and a poor prognosis. So far, standard systemic therapy for advanced iCCA has been a combination of gemcitabine and cisplatin. However, recent advancements in the understanding of the molecular characteristics of iCCA have opened new possibilities for molecular-targeted therapies and immunotherapy.

Summary

Reportedly, 9-36% of iCCA cases have an inflamed tumor immune microenvironment (TME) based on the immune gene expression signature, which is characterized by the presence of immune cells involved in anti-tumor immune responses. The majority of iCCA cases have a non-inflamed TME with a lack of effector T cells, rendering immune checkpoint inhibitors (ICIs) ineffective in these cases. Interestingly, alterations in the fibroblast growth factor receptor (FGFR2) gene and IDH1/2 gene mutations are often observed in the non-inflamed TME in iCCA. Several mechanisms have been reported for the role of driver mutations on the establishment of TME unique for iCCA. For example, IDH1/2 mutations, which cause an increase in DNA methylation, are associated with the downregulation and hypermethylation of antigen processing and presentation machinery, which may contribute to the establishment of a non-inflamed TME. Therefore, inhibitors targeting IDH1/2 may restore the DNA methylation and expression status of molecules involved in antigen presentation, potentially improving the efficacy of ICIs. FGFR inhibitors may also have the potential to modulate immunosuppressive TME by inhibitingthe suppressor of cytokine signaling 1 and activating the interferon-γ signaling as a consequence of inhibition of the FGFR signal. From this perspective, understanding the molecular characteristics of iCCA, including the TME and driver mutations, is essential for the effective application of ICIs and molecular-targeted therapies.

Key Messages

Combination approaches that target both the tumor and immune system hold promise for improving the outcomes of patients with iCCA. Further research and clinical trials are needed to validate these approaches and optimize the treatment strategies for iCCA.

Cancer cell genetics shaping of the tumor microenvironment reveals myeloid cell-centric exploitable vulnerabilities in hepatocellular carcinoma

Myeloid cells are abundant and plastic immune cell subsets in the liver, to which pro-tumorigenic, inflammatory and immunosuppressive roles have been assigned in the course of tumorigenesis. Yet several aspects underlying their dynamic alterations in hepatocellular carcinoma (HCC) progression remain elusive, including the impact of distinct genetic mutations in shaping a cancer-permissive tumor microenvironment (TME). Here, in newly generated, clinically-relevant somatic female HCC mouse models, we identify cancer genetics' specific and stage-dependent alterations of the liver TME associated with distinct histopathological and malignant HCC features. Mitogen-activated protein kinase (MAPK)-activated, NrasG12D-driven tumors exhibit a mixed phenotype of prominent inflammation and immunosuppression in a T cell-excluded TME. Mechanistically, we report a NrasG12D cancer cell-driven, MEK-ERK1/2-SP1-dependent GM-CSF secretion enabling the accumulation of immunosuppressive and proinflammatory monocyte-derived Ly6Clow cells. GM-CSF blockade curbs the accumulation of these cells, reduces inflammation, induces cancer cell death and prolongs animal survival. Furthermore, GM-CSF neutralization synergizes with a vascular endothelial growth factor (VEGF) inhibitor to restrain HCC outgrowth. These findings underscore the profound alterations of the myeloid TME consequential to MAPK pathway activation intensity and the potential of GM-CSF inhibition as a myeloid-centric therapy tailored to subsets of HCC patients.

Prognostic implications of tumor histology and microenvironment in surgically resected intrahepatic cholangiocarcinoma: a single institutional experience

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive malignant neoplasm. Certain histologic features and the tumor microenvironment may impact disease progression. We aim to characterize the clinicopathologic features of ICC to identify prognostic factors. A total of 50 surgically resected ICC (partial or transplant) cases were analyzed. The cohort included 26 men and 24 women with a median age of 62 years. Eighteen (36%) cases were multifocal ICC with a mean largest tumor size of 6.5 cm. Neoadjuvant and adjuvant chemotherapy was done in eight (16%) and 33 (66%) patients, respectively. Histologically, 42 (84%) were small duct type, seven (14%) large duct type, and one mixed (2%). Thirty (60%) cases showed lymphovascular invasion (LVI) and 11 (22%) with perineural invasion (PNI). Twenty-eight (56%) cases demonstrated dense intratumoral hyaline fibrosis and 18 (36%) with tumor necrosis, each ≥ 10% tumor volume. On follow-up, 35 (70%) patients died of disease after a median disease-specific survival (DSS) of 21 months. Univariate analysis revealed that hyaline fibrosis and adjuvant chemotherapy were associated with better DSS, while tumor size, multifocality, necrosis, and peritumoral neutrophil to lymphocyte ratio were associated with worse DSS. In contrast, age, sex, small vs. large duct types, LVI, and individual inflammatory cell counts were not significant prognostic factors. In summary, ICC is a heterogeneous malignancy with variable clinical courses associated with tumor burden, histology, and microenvironment. Targeting specific components within the tumor microenvironments may be a promising approach for treatment in the future.

Comprehensive Immunogenomic Profiling of IDH1-/2-Altered Cholangiocarcinoma

PURPOSE

Isocitrate dehydrogenase (IDH)1/2 genomic alterations (GA) occur in 20% of intrahepatic cholangiocarcinoma (iCCA); however, the immunogenomic landscape of IDH1-/2-mutated iCCA is largely unknown.

METHODS

Comprehensive genomic profiling (CGP) was performed on 3,067 cases of advanced iCCA. Tumor mutational burden (TMB), PD-L1 expression (Dako 22C3), microsatellite instability (MSI), and genomic loss of heterozygosity (gLOH) as a surrogate marker for homologous recombination deficiency were examined. RNA sequencing of 73 patient samples was analyzed for differences in stromal/immune cell infiltration, immune marker expression, and T-cell inflammation. Tissue microarray arrays were subjected to multiplex immunohistochemistry and colocalization analysis in 100 surgical samples. Retrospective clinical data were collected for 501 patients with cholangiocarcinoma to examine median overall survival (mOS) in IDH1/2+ versus IDHwt.

RESULTS

Of 3,067 iCCA cases subjected to CGP, 426 (14%) were IDH1+ and 125 (4%) were IDH2+. IDH1 GA included R132C (69%) and R132L/G/S/H/F (16%/7%/4%/3%/<1%). IDH2 GA occurred at R172 (94.4%) and R140 (6.6%). No significant difference was seen in median gLOH between IDH1+ versus IDHwt iCCA (P = .37), although patterns of comutations differed. MSI-High (P = .009), TMB ≥10 mut/Mb (P < .0001), and PD-L1 positivity were lower in IDH1/2+ versus IDHwt iCCA. Resting natural killer cell population, CD70, and programmed cell death 1 expression were significantly higher in non-IDH1-mutated cases, whereas V-set domain containing T-cell activation inhibitor 1 (B7-H4) expression was significantly higher in IDH1+. No significant difference in mOS was observed between IDH1/2+ versus IDHwt patients.

CONCLUSION

Significant differences in GA and immune biomarkers are noted between IDH1/2+ and IDHwt iCCA. IDH1-/2-mutated tumors appear immunologically cold without gLOH. These immunogenomic data provide insight for precision targeting of iCCA with IDH alterations.

Noncanonical TRAIL Signaling Promotes Myeloid-Derived Suppressor Cell Abundance and Tumor Growth in Cholangiocarcinoma

BACKGROUND & AIMS

Proapoptotic tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) signaling as a cause of cancer cell death is a well-established mechanism. However, TRAIL-receptor (TRAIL-R) agonists have had very limited anticancer activity in human beings, challenging the concept of TRAIL as a potent anticancer agent. Herein, we aimed to define mechanisms by which TRAIL+ cancer cells can leverage noncanonical TRAIL signaling in myeloid-derived suppressor cells (MDSCs) promoting their abundance in murine cholangiocarcinoma (CCA).

METHODS

Multiple immunocompetent syngeneic, orthotopic models of CCA were used. Single-cell RNA sequencing and cellular indexing of transcriptomes and epitopes by sequencing of CD45+ cells in murine tumors from the different CCA models was conducted.

RESULTS

In multiple immunocompetent murine models of CCA, implantation of TRAIL+ murine cancer cells into Trail-r-/- mice resulted in a significant reduction in tumor volumes compared with wild-type mice. Tumor-bearing Trail-r-/- mice had a significant decrease in the abundance of MDSCs owing to attenuation of MDSC proliferation. Noncanonical TRAIL signaling with consequent nuclear factor-κB activation in MDSCs facilitated enhanced MDSC proliferation. Single-cell RNA sequencing and cellular indexing of transcriptomes and epitopes by sequencing of immune cells from murine tumors showed enrichment of a nuclear factor-κB activation signature in MDSCs. Moreover, MDSCs were resistant to TRAIL-mediated apoptosis owing to enhanced expression of cellular FLICE inhibitory protein, an inhibitor of proapoptotic TRAIL signaling. Accordingly, cellular FLICE inhibitory protein knockdown sensitized murine MDSCs to TRAIL-mediated apoptosis. Finally, cancer cell-restricted deletion of Trail significantly reduced MDSC abundance and murine tumor burden.

CONCLUSIONS

Our findings highlight the therapeutic potential of targeting TRAIL+ cancer cells for treatment of a poorly immunogenic cancer.

Tumor immune microenvironment and the current immunotherapy of cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is a highly heterogeneous malignancy originating from the epithelial system of the bile ducts, and its incidence in recent years is steadily increasing. The immune microenvironment of CCA is characterized by diversity and complexity, with a substantial presence of cancer‑associated fibroblasts and immune cell infiltration, which plays a key role in regulating the distinctive biological behavior of cholangiocarcinoma, including tumor growth, angiogenesis, lymphangiogenesis, invasion and metastasis. Despite the notable success of immunotherapy in the treatment of solid tumors in recent years, patients with CCA have responded poorly to immune checkpoint inhibitor therapy. The interaction of tumor cells with cellular components of the immune microenvironment can regulate the activity and function of immune cells and form an immunosuppressive microenvironment, which may cause ineffective immunotherapy. Therefore, the components of the tumor immune microenvironment appear to be novel targets for immune therapies. Combination therapy focusing on immune checkpoint inhibitors is a promising and valuable first‑line or translational treatment approach for intractable biliary tract malignancies. The present review discusses the compositional characteristics and regulatory factors of the CCA immune microenvironment and the possible immune escape mechanisms. In addition, a summary of the advances in immunotherapy for CCA is also provided. It is hoped that the present review may function as a valuable reference for the development of novel immunotherapeutic strategies for CCA.

Immunogenomics of cholangiocarcinoma

The development of cholangiocarcinoma spans years, if not decades, during which the immune system becomes corrupted and permissive to primary tumor development and metastasis. This involves subversion of local immunity at tumor sites, as well as systemic immunity and the wider host response. While immune dysfunction is a hallmark of all cholangiocarcinoma, the specific steps of the cancer-immunity cycle that are perturbed differ between patients. Heterogeneous immune functionality impacts the evolutionary development, pathobiological behavior, and therapeutic response of these tumors. Integrative genomic analyses of thousands of primary tumors have supported a biological rationale for immune-based stratification of patients, encompassing immune cell composition and functionality. However, discerning immune alterations responsible for promoting tumor initiation, maintenance, and progression from those present as bystander events remains challenging. Functionally uncoupling the tumor-promoting or tumor-suppressing roles of immune profiles will be critical for identifying new immunomodulatory treatment strategies and associated biomarkers for patient stratification. This review will discuss the immunogenomics of cholangiocarcinoma, including the impact of genomic alterations on immune functionality, subversion of the cancer-immunity cycle, as well as clinical implications for existing and novel treatment strategies.

Bacterial Magnetosome-Hitchhiked Quick-Frozen Neutrophils for Targeted Destruction of Pre-Metastatic Niche and Prevention of Tumor Metastasis

Premetastatic niche (PMN) is a prerequisite for tumor metastasis. Destruction of PMN can significantly suppress the tumor metastasis. Bone marrow-derived cells are usually recruited into the premetastatic organs to support PMN formation, which can be orchestrated by tumor-derived secreted factors. Neutrophils can chemotactically migrate towards the inflammatory sites and consume tumor-derived secreted factors, capable of acting as therapeutic agents for a broad-spectrum suppression of PMN formation and metastasis. However, neutrophils in response to inflammatory signals can release neutrophil extracellular traps (NETs), promoting the tumor metastasis. Herein, live neutrophils are converted into dead neutrophils (C NE) through a quick-frozen process to maintain PMN-targeting and tumor-derived secreted factor-consuming abilities but eliminate NET-releasing shortcomings. Considering macrophages-regulated remodeling of the extracellular matrix in PMN, bacterial magnetosomes (Mag) are further hitchhiked on the surface of C NE to form C NEMag , which can repolarize macrophages from M2 to M1 phenotype for further disruption of PMN formation. A series of in vitro and in vivo assessments have been applied to confirm the effectiveness of C NEMag in suppression of PMN formation and metastasis. This study presents a promising strategy for targeted anti-metastatic therapy in clinics.

Targeting the Immunoglobulin IGSF9 Enhances Antitumor T-cell Activity and Sensitivity to Anti-PD-1 Immunotherapy

Immune checkpoints modulate the immune response and represent important immunotherapy targets for cancer treatment. However, as many tumors are resistant to current immune checkpoint inhibitors, the discovery of novel immune checkpoints could facilitate the development of additional immunotherapeutic strategies to improve patient responses. Here, we identified increased expression of the adhesion molecule immunoglobulin superfamily member 9 (IGSF9) in tumor cells and tumor-infiltrating immune cells across multiple cancer types. IGSF9 overexpression or knockout in tumor cells did not alter cell proliferation in vitro or tumor growth in immunocompromised mice. Alternatively, IGSF9 deficient tumor cells lost the ability to suppress T-cell proliferation and exhibited reduced growth in immunocompetent mice. Similarly, growth of tumor cells was reduced in IGSF9 knockout syngeneic and humanized mice, accompanied by increased tumor-infiltrating T cells. Mechanistically, the extracellular domain (ECD) of IGSF9 bound to T cells and inhibited their proliferation and activation, and the tumor-promoting effect of IGSF9 ECD was reversed by CD3+ T-cell depletion. Anti-IGSF9 antibody treatment inhibited tumor growth and enhanced the antitumor efficacy of anti-programmed cell death protein 1 immunotherapy. Single-cell RNA sequencing revealed tumor microenvironment remodeling from tumor promoting to tumor suppressive following anti-IGSF9 treatment. Together, these results indicate that IGSF9 promotes tumor immune evasion and is a candidate immune checkpoint target.

SIGNIFICANCE

IGSF9 is an immune checkpoint regulator that suppresses T-cell activation in cancer and can be targeted to stimulate antitumor immunity and inhibit tumor growth.

Immunobiology of cholangiocarcinoma

Recent literature has significantly advanced our knowledge and understanding of the tumour immune microenvironment of cholangiocarcinoma. Detailed characterisation of the immune landscape has defined new patient subtypes. While not utilised in clinical practice yet, these novel classifications will help inform decisions regarding immunotherapeutic approaches. Suppressive immune cells, such as tumour-associated macrophages and myeloid-derived suppressor cells, form a barrier that shields tumour cells from immune surveillance. The presence of this immunosuppressive barrier in combination with a variety of immune escape mechanisms employed by tumour cells leads to poor tumour immunogenicity. Broad strategies to re-equip the immune system include blockade of suppressive immune cell recruitment to priming cytotoxic effector cells against tumour antigens. While immunotherapeutic strategies are gaining traction for the treatment of cholangiocarcinoma, there is a long road of discovery ahead in order to make meaningful contributions to patient therapy and survival.

How I manage inpatient consultations for quantitative neutrophil abnormalities in adults

Neutrophilia and neutropenia commonly lead to inpatient hematology consultation. Quantitative neutrophil abnormalities have a broad differential and include diagnoses that are important to recognize because they may be associated with increased mortality. Neutrophilia can reflect etiologies such as infection, medications, inflammation, splenectomy, and congenital disorders. Neutropenia can arise from infection, medications, autoimmune destruction, sequestration, nutritional deficiency, malignancy, and congenital neutropenia syndromes. In the evaluation of all abnormalities of neutrophil number, the timing of the change, and the patient's historical neutrophil count are crucial.

Studies on the Role of Compartmentalized Profiles of Cytokines in the Risk of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the most common form of liver cancer, is frequently diagnosed late due to the absence of symptoms during early disease, thus heavily affecting the overall survival of these patients. Soluble immunological factors persistently produced during cirrhosis have been recognized as promoters of chronic inflammation and neoplastic transformation. The aim of this pilot study was to evaluate the predictive value of the cytokine profiles for HCC development. A Luminex xMAP approach was used for the quantification of 45 proteins in plasma and ascitic fluids of 44 cirrhotic patients without or with HCC of different etiologies. The association with patient survival was also evaluated. Univariate analyses revealed that very low levels of interleukin 5 (IL-5) (<15.86 pg/mL) in ascites and IL-15 (<12.40 pg/mL) in plasma were able to predict HCC onset with an accuracy of 81.8% and a sensitivity of 95.2%. Univariate analyses also showed that HCC, hepatitis B virus/hepatitis C virus infections, low levels of IL-5 and granulocyte-macrophage colony-stimulating factor in ascitic fluids, and high levels of eotaxin-1, hepatocyte growth factor and stromal-cell-derived factor 1α in plasma samples were factors potentially associated with a poor prognosis and decreased survival. Our results suggest a potential protective role of some immune modulators that may act in the peritoneal cavity to counteract disease progression leading to HCC development.

Cholangiocarcinoma tumor microenvironment highlighting fibrosis and matrix components

Cholangiocarcinoma (CCA) is an extremely aggressive malignancy characterized by a very limited prognosis and scarce treatment options. The majority of patients are diagnosed at an advanced stage and do not qualify for potentially curative surgical treatments, making CCA an increasingly prevalent global challenge. CCA is characterized by a highly reactive desmoplastic stroma, with complex mechanisms underlying the mutual interactions between tumor cells and stromal compartment. This review focuses on the recent studies examining CCA’s biological features, with particular reference to the tumor reactive stroma (TRS) and its role in CCA progression, including matrix remodeling, angiogenesis and lymphangiogenesis, metastasis, and immune evasion. After giving a panoramic view of the relationship between the tumoral and stromal compartment (cancer-associated fibroblast, CAFs and tumor-associated macrophages, TAMs), this review also discusses the current therapeutic approaches to counteract CAFs and TAMs effects on CCA progression.

Preclinical and clinical studies of immunotherapy for the treatment of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare primary liver cancer associated with high mortality and few systemic treatment options. The behaviour of the immune system has come into focus as a potential treatment modality for many cancer types, but immunotherapy has yet to dramatically alter the treatment paradigm for CCA as it has for other diseases. Herein, we review recent studies describing the relevance of the tumour immune microenvironment (TIME) in CCA. Various non-parenchymal cell types are critically important in controlling CCA progression, prognosis, and response to systemic therapy. Knowledge of the behaviour of these leukocytes could help generate hypotheses to guide the development of potential immune-directed therapies. Recently, an immunotherapy-containing combination was approved for the treatment of advanced-stage CCA. However, despite level 1 evidence demonstrating the improved efficacy of this therapy, survival remained suboptimal. In the current manuscript, we provide a comprehensive review of the TIME in CCA, preclinical studies of immunotherapies against CCA, as well as ongoing clinical trials applying immunotherapies for the treatment of CCA. Particular emphasis is placed on microsatellite unstable tumours, a rare CCA subtype that demonstrates heightened sensitivity to approved immune checkpoint inhibitors. We also discuss the challenges involved in applying immunotherapies to the treatment of CCA and the importance of understanding the TIME.

Cholangiocarcinoma - novel biological insights and therapeutic strategies

In the past 5 years, important advances have been made in the scientific understanding and clinical management of cholangiocarcinoma (CCA). The cellular immune landscape of CCA has been characterized and tumour subsets with distinct immune microenvironments have been defined using molecular approaches. Among these subsets, the identification of 'immune-desert' tumours that are relatively devoid of immune cells emphasizes the need to consider the tumour immune microenvironment in the development of immunotherapy approaches. Progress has also made in identifying the complex heterogeneity and diverse functions of cancer-associated fibroblasts in this desmoplastic cancer. Assays measuring circulating cell-free DNA and cell-free tumour DNA are emerging as clinical tools for detection and monitoring of the disease. Molecularly targeted therapy for CCA has now become a reality, with three drugs targeting oncogenic fibroblast growth factor receptor 2 (FGFR2) fusions and one targeting neomorphic, gain-of-function variants of isocitrate dehydrogenase 1 (IDH1) obtaining regulatory approval. By contrast, immunotherapy using immune-checkpoint inhibitors has produced disappointing results in patients with CCA, underscoring the requirement for novel immune-based treatment strategies. Finally, liver transplantation for early stage intrahepatic CCA under research protocols is emerging as a viable therapeutic option in selected patients. This Review highlights and provides in-depth information on these advances.

Minimally Invasive Treatment Options for Hepatic Uveal Melanoma Metastases

Uveal melanoma is one of the most common primary intraocular malignancies that accounts for about 85% of all ocular melanomas. The pathophysiology of uveal melanoma is distinct from cutaneous melanoma and has separate tumor profiles. The management of uveal melanoma is largely dependent on the presence of metastases, which confers a poor prognosis with a one-year survival reaching only 15%. Although a better understanding of tumor biology has led to the development of novel pharmacologic agents, there is increasing demand for minimally invasive management of hepatic uveal melanoma metastases. Multiple studies have already summarized the systemic therapeutic options available for metastatic uveal melanoma. This review covers the current research for the most prevalent locoregional treatment options for metastatic uveal melanoma including percutaneous hepatic perfusion, immunoembolization, chemoembolization, thermal ablation, and radioembolization.

KIF14 promotes proliferation, lymphatic metastasis and chemoresistance through G3BP1/YBX1 mediated NF-κB pathway in cholangiocarcinoma

Cholangiocarcinoma (CCA), a highly lethal and fetal cancer derived from the hepatobiliary system, is featured by aggressive growth and early lymphatic metastasis. Elucidating the underlying mechanism and identifying the effective therapy are critical for advanced CCA patients. In the study, we detected that KIF14 was upregulated in CCA samples, especially in patients with lymph node metastasis and vascular invasion. CCA patients with higher KIF14 were associated with worse overall survival and recurrence-free survival after surgery. Gain-of and loss-of function studies showed that KIF14 enhanced CCA cells proliferation, migration, invasion and lymphatic metastasis whereas its silencing abolished the effects in vivo and in vitro. Mechanistic investigation showed that KIF14 bound to the G3BP1/YBX1 complex and facilitated their interaction, causing increased activity of the NF-κB promoter and activation of NF-κB pathway. Furthermore, increased KIF14 level enhanced chemotherapy-resistance to gemcitabine-based regimen and induced immunosuppressive microenvironment. In addition, KIF14 was direct target of HNF4A and inversely regulated by HNF4A. Together, these findings suggested that KIF14 could be a potential oncogene and a good indicator in predicting prognosis and chemotherapy guidance for CCA patients.

Heterogeneity of Cholangiocarcinoma Immune Biology

Cholangiocarcinomas (CCAs) are aggressive tumors arising along the biliary tract epithelium, whose incidence and mortality are increasing. CCAs are highly desmoplastic cancers characterized by a dense tumor microenvironment (TME), in which each single component plays a fundamental role in shaping CCA initiation, progression and resistance to therapies. The crosstalk between cancer cells and TME can affect the recruitment, infiltration and differentiation of immune cells. According to the stage of the disease and to intra- and inter-patient heterogeneity, TME may contribute to either protumoral or antitumoral activities. Therefore, a better understanding of the effect of each immune cell subtype may open the path to new personalized immune therapeutic strategies for the management of CCA. In this review, we describe the role of immune cells in CCA initiation and progression, and their crosstalk with both cancer-associated fibroblasts (CAFs) and the cancer-stem-cell-like (CSC) niche.

Interaction of tumor-associated microglia/macrophages and cancer stem cells in glioma

Glioma is the most common tumor of the primary central nervous system, and its malignant phenotype has been shown to be closely related to glioma stem cells (GSCs). Although temozolomide has significantly improved the therapeutic outcome of glioma with a high penetration rate of the blood-brain barrier, resistance is often present in patients. Moreover, evidence has shown that the crosstalk between GSCs and tumor-associated microglia/macrophages (TAMs) affect the clinical occurrence, growth, and multi-tolerance of chemoradiotherapy in gliomas. Here, we highlight its vital roles in the maintenance of the stemness of GSCs and the ability of GSCs to recruit TAMs to the tumor microenvironment and promote their polarization into tumor-promoting macrophages, hence providing groundwork for future research into new treatment strategies of cancer.

Combining expression of RNF43 and infiltration level of CD163+ tumor associated macrophage predicts prognosis of clear cell renal cell carcinoma

Searching for reliable indicators for evaluating prognosis diagnosed with clear cell renal cell carcinoma (ccRCC) is crucial for improving clinical therapies. However, current researches have looked mainly at the prognostic value of a single intratumoral indicator, neglecting tumor-infiltrating immune cells (TIICs) in the microenvironment. This study examined whether the integration of Ring finger protein 43 (RNF43) expression and CD163⁺ tumor-associated macrophage (TAM) infiltration in combination with clinical indexes forecast ccRCC patient outcome with relatively high accuracy. Firstly, the expression of RNF43 and CD163 were detected with immunohistochemistry. Totally, 346 ccRCC patients were random separated evenly into training and validation datasets to make further analyses. We found that RNF43 expression was negatively correlated with infiltration level of CD163⁺ TAM in ccRCC, which was closely associated with the TNM stage and outcome of these patients. The multiple regression analysis demonstrated that RNF43, CD163, and TNM stage could function as independent risk factors in overall survival (OS) and progression-free survival (PFS) prediction of ccRCC. Furthermore, a better postoperative prognosis index for ccRCC patients was obtained by combining RNF43 and CD163⁺ TAMs, which assessed with time-dependent C-index analyses and a nomogram. Consequently, combining RNF43 and CD163⁺ TAMs along with TNM stage acquired robust accuracy in forecasting outcome of patients with ccRCC. In conclusion, combining intratumoral RNF43 expression, CD163⁺ TAM infiltration, and TNM stage could significantly enhance the veracity in forecasting postoperative outcomes.

Dense GM-CSFRα-expressing immune infiltration is allied with longer survival of intrahepatic cholangiocarcinoma patients

Background

Intrahepatic cholangiocarcinoma (iCCA) is a cancer arising from intrahepatic bile duct epithelium. An iCCA incidence is increasing worldwide; however, the outcome of the disease is dismal. The linkage between chronic inflammation and iCCA progression is well established, but the roles of granulocyte-macrophage colony-stimulating factor (GM-CSF) remain unrevealed. Thus, a better understanding of GM-CSF functions in CCA may provide an alternative approach to CCA treatment.

Methods

Differential GM-CSF and GM-CSFRα mRNA expressions in CCA tissues were investigated by Gene Expression Profiling Interactive Analysis (GEPIA) based on The Cancer Genome Atlas (TCGA) database. The protein expressions and localizations of GM-CSF and its cognate receptor (GM-CSFRα) in iCCA patients' tissues were demonstrated by the immunohistochemistry (IHC) techniques. The survival analyses were performed using Kaplan-Meier survival analysis with log-rank test and Cox proportional hazard regression model for multivariate analysis. The GM-CSF productions and GM-CSFRα expressions on CCA cells were assessed by ELISA and flow cytometry. The effects of GM-CSF on CCA cell proliferation and migration were evaluated after recombinant human GM-CSF treatment. The relationship between GM-CSF or GM-CSFRα level and related immune cell infiltration was analyzed using the Tumor Immune Estimation Resource (TIMER).

Results

GEPIA analysis indicated GM-CSF and GM-CSFRα expressions were higher in CCA tissues than in normal counterparts, and high GM-CSFRα was related to the longer disease-free survival of the patients (p < 0.001). IHC analysis revealed that CCA cells differentially expressed GM-CSF, while GM-CSFRα was expressed on cancer-infiltrating immune cells. The patient whose CCA tissue contained high GM-CSF expressed CCA, and moderate to dense GM-CSFRα-expressing immune cell infiltration (ICI) acquired longer overall survival (OS) (p = 0.047), whereas light GM-CSFRα-expressing ICI contributed to an increased hazard ratio (HR) to 1.882 (95% CI [1.077-3.287]; p = 0.026). In non-papillary subtype, an aggressive CCA subtype, patients with light GM-CSFRα-expressing ICI had shorter median OS (181 vs. 351 days; p = 0.002) and the HR was elevated to 2.788 (95% CI [1.299-5.985]; p = 0.009). Additionally, TIMER analysis demonstrated GM-CSFRα expression was positively correlated with neutrophil, dendritic cell, and CD8+ T cell infiltrations, though it was conversely related to M2-macrophage and myeloid-derived suppressor cell infiltration. However, the direct effects of GM-CSF on CCA cell proliferation and migration were not observed in the current study.

Conclusions

Light GM-CSFRα-expressing ICI was an independent poor prognostic factor for iCCA patients. Anti-cancer functions of GM-CSFRα-expressing ICI were suggested. Altogether, the benefits of acquired GM-CSFRα-expressing ICI and GM-CSF for CCA treatment are proposed herein and require elucidation.

No NETs no TIME: Crosstalk between neutrophil extracellular traps and the tumor immune microenvironment

The tumor immune microenvironment (TIME) controls tumorigenesis. Neutrophils are important components of TIME and control tumor progression and therapy resistance. Neutrophil extracellular traps (NETs) ejected by activated neutrophils are net-like structures composed of decondensed extracellular chromatin filaments decorated with a plethora of granules as well as cytoplasmic proteins. Many of these harbour post translational modifications. Cancer cells reportedly trigger NET formation, and conversely, NETs alter the TIME and promote tumor cell proliferation and migration. The specific interactions between NETs and TIME and the respective effects on tumor progression are still elusive. In certain tumors, a CD4+ T helper (Th) 2 cell-associated TIME induces NETs and exerts immunosuppressive functions via programmed death 1 (PD-1)/PD-L1, both associated with poorer prognosis. In other cases, NETs induce the proliferation of Th1 cells, associated with an improved prognosis in cancer. In addition, NETs can drive macrophage polarization and often rely on macrophages to promote cancer cell invasion and metastasis. In turn, macrophages can swiftly clear NETs in an immunologically silent manner. The aim of this review is to summarize the knowledge about the mutual interaction between NETs and TIME and its impact on tumor growth and therapy.

Interleukin-17D promotes lung cancer progression by inducing tumor-associated macrophage infiltration via the p38 MAPK signaling pathway

Cancer immunoediting is defined as the integration of the immune system’s dual host-protective and tumor-promoting roles, including three phases: elimination, equilibrium, and escape. Immune selective pressure causes tumor cells to lose major histocompatibility complex expression or acquire immunosuppressive gene expression, which promotes tumor immune evasion and tumor progression. Interleukin-17D (IL-17D), a member of the IL-17 family of cytokines, plays an important role in the host defense against infection and inflammation. However, the role of IL-17D in the progression of lung cancer remains unclear. In this study, we found that IL-17D was highly expressed in human lung cancer, and increased IL-17D expression was associated with tumor stage and short overall survival. IL-17D overexpression significantly promoted tumor growth in subcutaneous xenograft mouse models but only slightly affected cell proliferation in vitro. Using flow cytometry, we found that IL-17D overexpression enhances the recruitment of tumor-associated macrophages to the tumor microenvironment. Based on the expression profile of IL17D–overexpressing A549 cells, we found that IL-17D increased the expression levels of macrophage polarization– and recruitment–related genes through the MAPK signaling pathway. Moreover, inhibition of the p38 pathway blocked macrophage infiltration induced by IL-17D. These results suggest that IL-17D regulates the tumor immune microenvironment via the p38 MAPK signaling pathway, highlighting IL-17D as a potential therapeutic target for lung cancer.

GM-CSF: A Double-Edged Sword in Cancer Immunotherapy

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine that drives the generation of myeloid cell subsets including neutrophils, monocytes, macrophages, and dendritic cells in response to stress, infections, and cancers. By modulating the functions of innate immune cells that serve as a bridge to activate adaptive immune responses, GM-CSF globally impacts host immune surveillance under pathologic conditions. As with other soluble mediators of immunity, too much or too little GM-CSF has been found to promote cancer aggressiveness. While too little GM-CSF prevents the appropriate production of innate immune cells and subsequent activation of adaptive anti-cancer immune responses, too much of GM-CSF can exhaust immune cells and promote cancer growth. The consequences of GM-CSF signaling in cancer progression are a function of the levels of GM-CSF, the cancer type, and the tumor microenvironment. In this review, we first discuss the secretion of GM-CSF, signaling downstream of the GM-CSF receptor, and GM-CSF’s role in modulating myeloid cell homeostasis. We then outline GM-CSF’s anti-tumorigenic and pro-tumorigenic effects both on the malignant cells and on the non-malignant immune and other cells in the tumor microenvironment. We provide examples of current clinical and preclinical strategies that harness GM-CSF’s anti-cancer potential while minimizing its deleterious effects. We describe the challenges in achieving the Goldilocks effect during administration of GM-CSF-based therapies to patients with cancer. Finally, we provide insights into how technologies that map the immune microenvironment spatially and temporally may be leveraged to intelligently harness GM-CSF for treatment of malignancies.

Tumor microenvironment and immunology of cholangiocarcinoma

Cholangiocarcinoma (CCA), an aggressive tumor originating from both intra- and extra-hepatic biliary cells, represents an unmet need in liver oncology, as treatment remains largely unsatisfactory. A typical feature of CCA is the presence of a complex tumor microenvironment (TME) composed of neoplastic cells, a rich inflammatory infiltrate, and cancer-associated fibroblasts and desmoplastic matrix that makes it extremely chemoresistant to traditional chemotherapeutic drugs. In this review, we describe the cell populations within the TME, in particular those involved in the innate and adaptive immune response and how they interact with tumor cells and with matrix proteins. The TME is crucial for CCA to mount an immune escape response and is the battlefield where molecularly targeted therapies and immune therapy, particularly in combination, may actually prove their therapeutic value.