High density of FOXP3-positive T cells infiltrating colorectal cancers with microsatellite instability

Transforming Albumin into a Trojan Horse of Immunotherapy-Resistant Colorectal Cancer with a High Microsatellite Instability

The therapeutic response of microsatellite instability-high (MSI-H) colorectal cancer (CRC) to immune checkpoint inhibitors (ICI) is indeed surprising; however, the emergence of acquired resistance poses an even greater threat to the survival of these patients. Herein, bioinformatics analysis of MSI-H CRC samples revealed that Wnt signaling pathway represents a promising target for acquired immune reactivation, while subsequent analysis and biochemical testing substantiated the inclination of Wnt-hyperactive CRC cells to engage in macropinocytosis with human serum albumin (HSA). These findings have inspired us to develop an engineered HSA that not only possesses the ability to specifically target cancer cells but also effectively suppresses the Wnt/β-catenin cascade within these malignant cells. In pursuit of this objective, a comprehensive screening of reported Wnt small-molecule inhibitors was conducted to evaluate their affinity with HSA, and it was discovered that Carnosic acid (CA) exhibited the highest affinity while simultaneously revealing multiple binding sites. Further investigation revealed that CA HSA the capability to engineer HSA into spherical and size-tunable nanostructures known as eHSA (Engineering HSA particle), which demonstrated optimized macropinocytosis-dependent cellular internalization. As anticipated, eHSA effectively suppressed the Wnt signaling pathway and reactivated the acquired immune response in vivo. Furthermore, eHSA successfully restored sensitivity to Anti-PD1's anticancer effects in both subcutaneous and orthotopic mouse homograft models of MSI-H CRC, as well as a humanized hu-PBMC patient-derived orthotopic xenograft (PDOX) mouse model of MSI-H CRC, all while maintaining a favorable safety profile. The collective implementation of this clinically viable immune reactivation strategy not only enables the delivery of Wnt inhibitors for CRC therapy, but also serves as an exemplary demonstration of precision-medicine-guided nanopharmaceutical development that effectively harnesses specific cellular indications in pathological states.

Decreased interleukin-17RA expression is associated with good prognosis in patients with colorectal cancer and inhibits tumor growth and vascularity in mice

BACKGROUND

Interleukin-17 (IL-17) is a pro-inflammatory cytokine that plays a vital role in the promotion of tumorigenesis in various cancers, including colorectal cancer (CRC). Based on current evidence, IL-17 binds to interleukin-17 receptor A (IL-17RA); however, the role of IL-17RA has not been elucidated in previous studies on CRC. In this study, we explored the role of IL-17RA in human CRC tissues and the progression of CRC in humans and mice.

METHODS

The expressions of IL-17RA and epithelial-mesenchymal transition (EMT)-related genes were examined in CRC cells and tissue samples by quantitative real-time polymerase chain reaction. The role of IL-17RA in pathogenesis and prognosis was evaluated using a Chi-squared test, Kaplan-Meier analysis, univariate, and multivariate Cox regression analysis in 133 CRC patients. A tumor-bearing mice model was executed to evaluate the role of IL-17RA in tumor growth, vascularity and population of infiltrating immune cells.

RESULTS

IL-17RA expression was found to be significantly higher in CRC tissues than in adjacent normal tissues. The expression of IL-17RA in Stage IV patients was significantly higher than that in Stages I and II patients. Patients with high IL-17RA expression exhibited significantly worse overall and CRC-specific survival than those with low IL-17RA expression. Functional assessment suggested that the knockdown of IL-17RA expression distinctly suppressed cellular proliferation, migration, invasion, and EMT-related gene expression. In a tumor-bearing mouse model, decreased IL-17RA expression significantly repressed tumor growth and vascularity and reduced the population of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs).

CONCLUSION

Reduced IL-17RA expression also suppressed cellular proliferation, migration, and invasion, and the expression of EMT genes. Knockdown of IL-17RA inhibited tumor growth and vascularity and decreased the population of Tregs and MDSCs in mouse tumors. Overall, IL-17RA expression was identified to be independently associated with the prognosis of patients with CRC.

Immunomodulatory effects of iTr35 cell subpopulation and its research progress

The spotlight in recent years has increasingly focused on inducible regulatory T cells 35 (iTr35), a novel subpopulation of regulatory T cells characterized by phenotypic stability, heightened reactivity, and potent immunosuppressive function through the production of IL-35. Despite being in the exploratory phase, research on iTr35 has garnered significant interest. In this review, we aim to consolidate our understanding of the biological characteristics and immunomodulatory mechanisms of iTr35, offering fresh perspectives that may pave the way for its potential applications in disease diagnosis and treatment.

Mismatch repair gene MSH6 correlates with the prognosis, immune status and immune checkpoint inhibitors response of endometrial cancer

Objective

Many patients treated with immune checkpoint inhibitors (ICIs) developed primary or secondary drug resistance for unknown reasons. This study investigates whether mismatch repair (MMR) genes are responsible for this therapeutic restriction.

Methods

We obtained the transcriptional, clinical and single nucleotide polymorphism data for endometrial cancer (EC) from The Cancer Genome Atlas and the immunophenoscore data of EC from The Cancer Immunome Atlas, then analyzed in R to evaluate the relationship between MMR genes and clinicopathological features, prognosis, immune infiltration, immune checkpoint expression and responsiveness to ICIs in EC. We used differentially expressed genes in the MSH6 high and low expression groups to conduct GO and KEGG analyses to explore the impact of MSH6 on the biological functions of EC. Finally, we verified the bioinformatics results with in vitro experiments.

Results

Our analyses showed that compared with the high MSH6 expression group, the low MSH6 expression group had better survival outcomes and less aggressive clinicopathological features. In the multivariate Cox analysis, MSH6 was the only independent risk factor that could predict the prognosis of EC. Besides, the low MSH6 expression group also had a higher immune score, more active immune infiltration and higher immune checkpoint expression, resulting in better responsiveness to ICIs treatment, consistent with the enrichment of GO terms and KEGG pathways related to immune response in this group. Meanwhile, the GO and KEGG enrichment results of the MSH6 high expression group were associated with cell cycle, DNA damage repair and tumorigenesis. To exclude the influence of MSH6 mutations, we performed the previous analyses on the MSH6 wild-type tumor samples and obtained consistent results. In vitro experiments also confirmed that after knocking down MSH6 in endometrial cancer cells, their proliferation, migration and invasion abilities were weakened, while the expression levels of PD-L1 and PD-L2 were elevated. In comparison, overexpression of MSH6 showed an opposite trend.

Conclusion

Reduced MSH6 expression could serve as a potential biomarker for predicting better prognosis, active immune status, higher immune checkpoint expression level and better responsiveness to ICIs treatment in EC. MSH6 may become a potential target for treating solid tumors.

Unraveling Resistance to Immunotherapy in MSI-High Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related deaths. Incidences of early CRC cases are increasing annually in high-income countries, necessitating effective treatment strategies. Immune checkpoint inhibitors (ICIs) have shown significant clinical efficacy in various cancers, including CRC. However, their effectiveness in CRC is limited to patients with mismatch-repair-deficient (dMMR)/microsatellite instability high (MSI-H) disease, which accounts for about 15% of all localized CRC cases and only 3% to 5% of metastatic CRC cases. However, the varied response among patients, with some showing resistance or primary tumor progression, highlights the need for a deeper understanding of the underlying mechanisms. Elements involved in shaping the response to ICIs, such as tumor microenvironment, immune cells, genetic changes, and the influence of gut microbiota, are not fully understood thus far. This review aims to explore potential resistance or immune-evasion mechanisms to ICIs in dMMR/MSI-H CRC and the cell types involved, as well as possible pitfalls in the diagnosis of this particular subtype.

DNA mismatch repair in cancer immunotherapy

Tumors defective in DNA mismatch repair (dMMR) exhibit microsatellite instability (MSI). Currently, patients with dMMR tumors are benefitted from anti-PD-1/PDL1-based immune checkpoint inhibitor (ICI) therapy. Over the past several years, great progress has been made in understanding the mechanisms by which dMMR tumors respond to ICI, including the identification of mutator phenotype-generated neoantigens, cytosolic DNA-mediated activation of the cGAS-STING pathway, type-I interferon signaling and high tumor-infiltration of lymphocytes in dMMR tumors. Although ICI therapy shows great clinical benefits, ∼50% of dMMR tumors are eventually not responsive. Here we review the discovery, development and molecular basis of dMMR-mediated immunotherapy, as well as tumor resistant problems and potential therapeutic interventions to overcome the resistance.

The M2 macrophages infiltration of sebaceous tumors is linked to the aggressiveness of tumors but not to the mismatch repair pathway

PURPOSE

The immune microenvironment of sebaceous neoplasms (SNs) has been poorly explored, especially in benign lesions, and never correlated to the mismatch repair (MMR) status.

METHODS

We conducted an immuno-histological study to analyze the immune microenvironment of SNs. A tissue microarray was constructed including sebaceous adenomas (SAs), sebaceomas (Ss) and sebaceous carcinomas (SCs) to performed immuno-histological analysis of T cells, B cells, macrophages, dendritic cells, and expression of Programmed Death-1 (PD-1) and Programmed Death Ligand 1 (PD-L1). An automatized count was performed using the QuPath® software. Composition of the cellular microenvironment was compared to the aggressiveness, the MMR status, and to Muir-Torre syndrome (MTS).

RESULTS

We included 123 SNs (43 SAs, 19 Ss and 61 SCs) for which 71.5% had a dMMR phenotype. A higher infiltration of macrophages (CD68 +) of M2 phenotype (CD163 +) and dendritic cells (CD11c +) was noticed in SCs compared to benign SNs (SAs and Ss). Programmed cell death ligand-1 but not PD-1 was expressed by more immune cells in SCs compared to benign SNs. No difference in the immune cell composition regarding the MMR status, or to MTS was observed.

CONCLUSION

In SNs, M2 macrophages and dendritic cells infiltrates are associated with the progression and the malignant transformation of tumors. High PD-L1 expression in immune cells in SCs is an argument for the use of immunotherapy by anti-PD1 or PD-L1 in metastatic patients. The lack of correlation between the composition of immune cells in SNs and the MMR status emphasizes the singularity of SNs among MMR-associated malignancies.

Genetic and pharmacological modulation of DNA mismatch repair heterogeneous tumors promotes immune surveillance

Patients affected by colorectal cancer (CRC) with DNA mismatch repair deficiency (MMRd), often respond to immune checkpoint blockade therapies, while those with mismatch repair-proficient (MMRp) tumors generally do not. Interestingly, a subset of MMRp CRCs contains variable fractions of MMRd cells, but it is unknown how their presence impacts immune surveillance. We asked whether modulation of the MMRd fraction in MMR heterogeneous tumors acts as an endogenous cancer vaccine by promoting immune surveillance. To test this hypothesis, we use isogenic MMRp (Mlh1^+/+) and MMRd (Mlh1^-/-) mouse CRC cells. MMRp/MMRd cells mixed at different ratios are injected in immunocompetent mice and tumor rejection is observed when at least 50% of cells are MMRd. To enrich the MMRd fraction, MMRp/MMRd tumors are treated with 6-thioguanine, which leads to tumor rejection. These results suggest that genetic and pharmacological modulation of the DNA mismatch repair machinery potentiate the immunogenicity of MMR heterogeneous tumors.

Hallmarks of Cancer Expression in Oral Lichen Planus: A Scoping Review of Systematic Reviews and Meta-Analyses

Oral lichen planus (OLP) is a common chronic inflammatory disease of unknown etiology and likely autoimmune nature that is currently considered an oral potentially malignant disorder, implying that patients suffering from this process are at risk of developing oral cancer in their lifetime. The molecular alterations that develop in OLP and that make the affected oral epithelium predisposed to malignancy are unknown, although, as in other autoimmune diseases (ulcerative colitis, primary biliary cirrhosis, etc.), they may be linked to oncogenesis-promoting effects mediated by the inflammatory infiltrate. So far there is no in-depth knowledge on how these hallmarks of cancer are established in the cells of the oral epithelium affected by OLP. In this scoping review of systematic reviews and meta-analyses the state of evidence based knowledge in this field is presented, to point out gaps of evidence and to indicate future lines of research. MEDLINE, Embase, Cochrane Library and Dare were searched for secondary-level studies published before October 2022. The results identified 20 systematic reviews and meta-analyses critically appraising the hallmarks tumor-promoting inflammation (n = 17, 85%), sustaining proliferative signaling (n = 2, 10%), and evading growth suppressors (n = 1, 5%). No evidence was found for the other hallmarks of cancer in OLP. In conclusion, OLP malignization hypothetically derives from the aggressions of the inflammatory infiltrate and a particular type of epithelial response based on increased epithelial proliferation, evasion of growth-suppressive signals and lack of apoptosis. Future evidence-based research is required to support this hypothesis.

Hallmarks of Cancer Applied to Oral and Oropharyngeal Carcinogenesis: A Scoping Review of the Evidence Gaps Found in Published Systematic Reviews

Simple Summary

This scoping review of systematic reviews aims to accurately assess the degree of existing scientific evidence on the cancer hallmarks proposed in 2011 by Hanahan and Weinberg, in the form of systematic reviews and meta-analyses, applied to oral potentially malignant disorders, oral cavity and oropharyngeal squamous cell carcinomas, in order to point out gaps in evidence and lines of research that should be implemented in the future to improve the malignant transformation prediction, diagnosis and/or prognosis of these diseases.

Abstract

In 2000 and 2011, Hanahan and Weinberg published two papers in which they defined the characteristics that cells must fulfil in order to be considered neoplastic cells in all types of tumours that affect humans, which the authors called “hallmarks of cancer”. These papers have represented a milestone in our understanding of the biology of many types of cancers and have made it possible to reach high levels of scientific evidence in relation to the prognostic impact that these hallmarks have on different tumour types. However, to date, there is no study that globally analyses evidence-based knowledge on the importance of these hallmarks in oral and oropharyngeal squamous cell carcinomas. For this reason, we set out to conduct this scoping review of systematic reviews with the aim of detecting evidence gaps in relation to the relevance of the cancer hallmarks proposed by Hanahan and Weinberg in oral and oropharyngeal cancer, and oral potentially malignant disorders, and to point out future lines of research in this field.

Tumor-Infiltrating Lymphocytes in Colorectal Cancer: The Fundamental Indication and Application on Immunotherapy

The clinical success of immunotherapy has revolutionized the treatment of cancer patients, bringing renewed attention to tumor-infiltrating lymphocytes (TILs) of various cancer types. Immune checkpoint blockade is effective in patients with mismatched repair defects and high microsatellite instability (dMMR-MSI-H) in metastatic colorectal cancer (CRC), leading the FDA to accelerate the approval of two programmed cell death 1 (PD-1) blocking antibodies, pembrolizumab and nivolumab, for treatment of dMMR-MSI-H cancers. In contrast, patients with proficient mismatch repair and low levels of microsatellite stability or microsatellite instability (pMMR-MSI-L/MSS) typically have low tumor-infiltrating lymphocytes and have shown unsatisfied responses to the immune checkpoint inhibitor. Different TILs environments reflect different responses to immunotherapy, highlighting the complexity of the underlying tumor-immune interaction. Profiling of TILs fundamental Indication would shed light on the mechanisms of cancer-immune evasion, thus providing opportunities for the development of novel therapeutic strategies. In this review, we summarize phenotypic diversities of TILs and their connections with prognosis in CRC and provide insights into the subsets-specific nature of TILs with different MSI status. We also discuss current clinical immunotherapy approaches based on TILs as well as promising directions for future expansion, and highlight existing clinical data supporting its use.

Intratumoral density of regulatory T cells is a predictor of host immune response and chemotherapy response in colorectal cancer

Regulatory T cells (Tregs) are a subset of CD4+ T lymphocytes known to dampen the host immune response against cancer cells. Within the tumor microenvironment, Tregs are potent facilitators of immune tolerance, and a higher proportion of Tregs compared to cytotoxic T cells predicts a worse outcome in most solid tumors. We studied the association between Treg density, and cancer biology and clinical outcome in colorectal cancer (CRC). We used xCell to estimate intratumoral Tregs in total of 898 CRC patients in the Cancer Genome Atlas (TCGA) and GCE39582 cohorts. High-Treg CRCs enriched immune response-related gene sets; inflammatory response, IFN-γ and IFN-α response, IL2/IL6 signaling, and allograft rejection, and had significantly high infiltration of CD8, CD4, M1 and M2 macrophage, and dendritic cells in both cohorts. While high-Treg CRCs enriched multiple pro-cancer signaling pathways compared to low-Treg CRCs, such as Epithelial Mesenchymal Transition, K-ras, Hypoxia, TGF-β, TNF-α, and angiogenesis, Treg infiltration was surprisingly associated with earlier CRC stage in TCGA. Notably, in two separate cohorts a higher proportion of Tregs predicted an improved response to chemotherapy. In the GSE28702 cohort, metastatic CRCs with more Tregs showed a significantly better response to mFOLFOX6 versus low-Treg CRC metastases (88.9% response vs. 16.7%, P<0.001). In the GSE72970 cohort, high-Treg CRCs were found to have a 68.8% response to FOLFOX/FOLFIRI without bevacizumab, compared to 44% response in the low-Treg CRCs. Additionally, high-Treg CRCs were associated with increased expression of immune checkpoint molecules PD-L1/PD-L2, CTLA4, TIGIT and BTLA, implying susceptibility to immunotherapy. We also found that CRCs with higher proportions of Tregs were associated with lower amounts of three microorganisms in the tumor: Lachnoclostridium, flavivirus, and Ornithobacterium. In conclusion, we show that amount of Treg in the tumor is a predictor of host immune response and chemotherapy response in CRC.

The Impact of Mismatch Repair Status on Prognosis of Patients With Gastric Cancer: A Multicenter Analysis

BACKGROUND

The clinical role of deficient DNA mismatch repair (dMMR)/microsatellite instability-high (MSI-H) in gastric cancer (GC) is still controversial. We aimed to analyze the relationship between dMMR/MSI-H and clinicopathological features along with survival.

METHODS

Patients who were diagnosed with GC at the three big cancer centers in China from 2015 to 2020 were evaluated retrospectively. MMR/MSI status was assessed using immunohistochemistry/PCR. Clinical and pathological data were collected from the medical record system.

RESULTS

A total of 196 patients with dMMR/MSI-H status were enrolled for analysis. The prevalence of MSI-H/dMMR in GC was 6.6%. Another 694 proficient MMR (pMMR) GC patients were enrolled for comparison. Compared with pMMR patients, dMMR/MSI-H patients were associated with older age, female predominance, distal location in the stomach, earlier TNM stage, intestinal subtype, better differentiation, and more negative HER2 status. The median overall survival (OS) of the dMMR/MSI-H group was better than that of the pMMR/microsatellite stability (MSS) group (not reached vs. 53.9 months, p = 0.014). Adjuvant chemotherapy had no impact in both disease-free survival (DFS) and OS of dMMR/MSI-H patients (p = 0.135 and 0.818, respectively). dMMR/MSI-H patients had poorer response and progression-free survival (PFS) of first-line chemotherapy, though they were statistically significant (p = 0.361 and 0.124, respectively).

CONCLUSIONS

dMMR/MSI-H GC patients have specific clinicopathological characteristics and better prognosis than pMMR patients.

Intratumoral regulatory T cells from colon cancer patients comprise several activated effector populations

Background

Intratumoral regulatory T cells (Treg) in colon cancer are a heterogeneous cell population, with potential impact on patient outcome. Generally, a high Treg infiltration has been correlated to a worse patient outcome, but it is still unclear how the composition of different Treg subsets affects patient relapse and survival. In this study, we used mass and flow cytometry to characterize Treg in colon tumors and corresponding unaffected tissue, followed by a correlation to clinical parameters and patient outcome.

Results

Using mass cytometry, we defined 13 clusters of intestinal Treg, three of which were enriched in the tumors. The two most enriched clusters were defined by their expression of the proliferation marker Ki67 and CD56, respectively. The Treg accumulating in the tumors expressed inducible T-cell co-stimulator (ICOS), OX-40, and CD39, indicating that they were effector Treg (eTreg). Intratumoral CD39⁺ Treg also had a higher expression of Foxp3, suggesting a higher suppressive activity, and we subsequently used CD39 as a marker for eTreg. Our further studies showed that colon tumors can be divided into two tumor groups, based on the proportion of CD39⁺ putative eTreg in the tumors. This property was independent of both tumor microsatellite status and tumor stage, which are important factors in predicting cancer disease progression. In a prospective study of forty-four colon cancer patients, we also showed that patients with a high CD39 expression on tumor-infiltrating Treg have a tendency towards a less favorable patient outcome in terms of cumulative cancer-specific survival.

Conclusions

This study uncovers novel subsets of tumor-infiltrating Treg in colon cancer, and suggests that CD39 may be a potential therapeutic target in patients with microsatellite stable colon tumors, which are usually refractory to checkpoint blockade therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00449-1.

Regulatory T cells reduce endothelial neutral sphingomyelinase 2 to prevent T-cell migration into tumors

Endothelial cells are key regulators of transendothelial migration and their secretion of chemokines and expression of adhesion molecules facilitates lymphocyte entry into tissues. Previously, we demonstrated that Tregs can reduce transendothelial migration of T cells into tumors by decreasing endothelial CXCL10 secretion, but the mechanism by which this occurs is still not known. In this study, we aimed to define how Tregs decrease transendothelial migration into tumors. mRNA sequencing of intestinal tumor endothelial cells from Treg depleted mice identified neutral sphingomyelinase 2 (nSMase2) as a gene downregulated in the presence of Tregs. nSMase2 is expressed in human umbilical vein endothelial cells (HUVECs) and was decreased after coculture with Tregs. Furthermore, blocking of nSMase2 activity in vitro decreased VCAM1, CX3CL1, and CXCL10 expression in HUVECs, mirroring the same decrease found in Treg cocultures. In the APC^min/+ mouse model of intestinal cancer, nSMase2 is lower in tumor endothelial cells than in unaffected small intestine and chronic treatment with a nSMase2 inhibitor suppressed the increased migration that is otherwise seen in the absence of Tregs. We conclude that nSMase2 is an important mediator in endothelial cells supporting transendothelial migration, which may be targeted by Tregs to reduce T-cell migration into tumors.

Mechanisms of Immune Escape and Resistance to Checkpoint Inhibitor Therapies in Mismatch Repair Deficient Metastatic Colorectal Cancers

Simple Summary

A subset of colorectal cancers (CRCs) is characterized by a mismatch repair deficiency that is frequently associated with microsatellite instability (MSI). The compromised DNA repair machinery leads to the accumulation of tumor neoantigens affecting the sensitivity of MSI metastatic CRC to immune checkpoint inhibitors (CPIs), both upfront and in later lines of treatment. However, up to 30% of MSI CRCs exhibit primary resistance to frontline immune based therapy, and an additional subset develops acquired resistance. Here, we first discuss the clinical and molecular features of MSI CRCs and then we review how the loss of antigenicity, immunogenicity, and a hostile tumor microenvironment could influence primary and acquired resistance to CPIs. Finally, we describe strategies to improve the outcome of MSI CRC patients upon CPI treatment.

Abstract

Immune checkpoint inhibitors (CPIs) represent an effective therapeutic strategy for several different types of solid tumors and are remarkably effective in mismatch repair deficient (MMRd) tumors, including colorectal cancer (CRC). The prevalent view is that the elevated and dynamic neoantigen burden associated with the mutator phenotype of MMRd fosters enhanced immune surveillance of these cancers. In addition, recent findings suggest that MMRd tumors have increased cytosolic DNA, which triggers the cGAS STING pathway, leading to interferon-mediated immune response. Unfortunately, approximately 30% of MMRd CRC exhibit primary resistance to CPIs, while a substantial fraction of tumors acquires resistance after an initial benefit. Profiling of clinical samples and preclinical studies suggests that alterations in the Wnt and the JAK-STAT signaling pathways are associated with refractoriness to CPIs. Intriguingly, mutations in the antigen presentation machinery, such as loss of MHC or Beta-2 microglobulin (B2M), are implicated in initial immune evasion but do not impair response to CPIs. In this review, we outline how understanding the mechanistic basis of immune evasion and CPI resistance in MMRd CRC provides the rationale for innovative strategies to increase the subset of patients benefiting from CPIs.

The Mechanisms Leading to Distinct Responses to PD-1/PD-L1 Blockades in Colorectal Cancers With Different MSI Statuses

Current clinical studies showed distinct therapeutic outcomes, in which CRC patients with mismatch repair-deficient (dMMR)/microsatellite instability high (MSI-H) seem to be relatively more "sensitive" in response to anti-programmed death-1 receptor (PD-1)/programmed death-1 receptor ligand 1 (PD-L1) therapy than those with mismatch repair-proficient (pMMR)/microsatellite instability-low (MSI-L). The mechanisms by which the same PD-1/PD-L1 blockades lead to two distinct therapeutic responses in CRC patients with different MSI statuses remain poorly understood and become a topic of great interest in both basic research and clinical practice. In this review of the potential mechanisms for the distinct response to PD-1/PD-L1 blockades between dMMR/MSI-H CRCs and pMMR/MSI-L CRCs, relevant references were electronically searched and collected from databases PubMed, MEDLINE, and Google scholar. Sixty-eight articles with full text and 10 articles by reference-cross search were included for final analysis after eligibility selection according to the guidelines of PRISMA. Analysis revealed that multiple factors e.g. tumor mutation burden, immune cell densities and types in the tumor microenvironment, expression levels of PD-1/PD-L1 and cytokines are potential determinants of such distinct response to PD-1/PD-L1 blockades in CRC patients with different MSI statuses which might help clinicians to select candidates for anti-PD-1/PD-L1 therapy and improve therapeutic response in patients with CRC.

Intestinal Regulatory T Cells

Mucosal surfaces are distinctive sites exposed to environmental, dietary, and microbial antigens. Particularly in the gut, the host continuously actively adapts via complex interactions between the microbiota and dietary compounds and immune and other tissue cells. Regulatory T cells (Tregs) are critical for tuning the intestinal immune response to self- and non-self-antigens in the intestine. Its importance in intestinal homeostasis is illustrated by the onset of overt inflammation caused by deficiency in Treg generation, function, or stability in the gut. A substantial imbalance in Tregs has been observed in intestinal tissue during pathogenic conditions, when a tightly regulated and equilibrated system becomes dysregulated and leads to unimpeded and chronic immune responses. In this chapter, we compile and critically discuss the current knowledge on the key factors that promote Treg-mediated tolerance in the gut, such as those involved in intestinal Treg differentiation, specificity and suppressive function, and their immunophenotype during health and disease. We also discuss the current state of knowledge on Treg dysregulation in human intestine during pathological states such as inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), graft-versus-host disease (GVHD), and colorectal cancer (CRC), and how that knowledge is guiding development of Treg-targeted therapies to treat or prevent intestinal disorders.

Clinicopathological characterization and prognostic implication of FOXP3 and CK19 expression in papillary thyroid carcinoma and concomitant Hashimoto's thyroiditis

Papillary thyroid carcinoma (PTC) is considered the most prevalent thyroid malignancy. The association between Hashimoto's thyroiditis (HT) and PTC is still unclear. We aimed to examine the clinicopathological impact of immunohistochemical staining of FOXP3 and Cytokeratin 19 in PTC and concomitant HT and their correlation with patients' outcome and survival. Eighty thyroid biopsies obtained from patients with PTC were immunostained by FOXP3 and CK19.The patients were treated by radioactive iodine (I131) and followed up. FOXP3 and CK19 expression were detected in 45% and 80% studied cases of PTC respectively. 16.7% of PTC with associated HT showed FOXP3+ lymphocytes in lymphocytic infiltrate of HT, while most of PTC associated HT express cytoplasmic CK19 positive Hurtle cells. FOXP3 was more expressed in PTC female patients more than 45 years with higher stage, lymph node, and distant metastasis, extracapsular extension, number of I131doses, and cumulative radioiodine doses with a highly statistically significant difference (p < 0.001). The relation was significant between CK19 immunostaining as regard 10-year Overall Survival and death (p value = 0.027 and 0.036, respectively). HT represents a step in the process of autoimmune inflammatory disease ending by the evolution of PTC with better prognosis, therefore appropriate follow up of these cases is needed. FOXP3 tends to be more expressed in PTC cases with worse prognostic variables and is predictable to become a recent prognostic and targeted therapy for PTC. There was a significant relation between CK19 immunostaining and 10 year overall survival.

Density and distribution of lymphocytes in pretherapeutic rectal cancer and response to neoadjuvant therapy

Background

Lymphocytic density in rectal cancer has been reported to be associated with therapeutic response, but the role of the lymphocytic distribution pattern remains to be determined. This study aimed to evaluate the association between the distribution and density of lymphocytes in rectal-cancer tissue with tumor response to neoadjuvant therapy.

Methods

We retrospectively analysed 134 patients with rectal cancer receiving neoadjuvant therapy within a prospectively maintained cohort. Pretherapeutic biopsy samples were stained with immunohistochemistry (CD4 and CD8). Densities of intratumoral periglandular lymphocytes (IPLs) and tumor-infiltrating lymphocytes (TILs) were assessed separately. Logistic-regression analysis was used to assess associations of lymphocyte densities with tumor regression grade (TRG), controlling for clinicopathological, molecular, and regimen features.

Results

Compared with cases in the lowest quartile of CD8⁺ TILs, those in the highest quartile were significantly associated with better TRG (multivariate odds ratio, 0.23; 95% confidence interval, 0.07 to 0.76; P < 0.001). In contrast, CD8⁺ IPLs, CD4⁺ IPLs, and CD4⁺ TILs were not significantly associated with TRG (P = 0.033, 0.156, and 0.170, respectively). Sensitivity analyses detected no interaction between CD8⁺ TILs and regimen of neoadjuvant radiation (P_interaction = 0.831) or chemotherapy (P_interaction = 0.879) on TRG.

Conclusions

Our data suggest that CD8⁺ TILs, but not IPLs, are independently associated with response to neoadjuvant therapy, regardless of the regimen of radiation or chemotherapy.

ST2 and regulatory T cells in the colorectal adenoma/carcinoma microenvironment: implications for diseases progression and prognosis

ST2 (also known as IL1RL1) is the critical functional receptor for interleukin (IL)-33 in stimulating regulatory T cell (Treg) expansion and function in physiological and pathological conditions. We examined the correlation between ST2 cell expression and FoxP3 positive Tregs in both colorectal adenoma and cancer (CRC) microenvironment by real-time PCR, immunohistochemistry (IHC) and double immunofluorescences. The clinicopathological and prognostic significance of cellular ST2-positive cells and FoxP3-positive Tregs in patients with adenoma and CRC were evaluated. Real-time PCR results revealed increased expression levels of ST2 and FoxP3 mRNAs in both adenoma and CRC tissues as compared with control tissues. IHC analysis confirmed increased densities of ST2-positive cells in both the adenoma/CRC epithelium and stroma, which show a close positive linear association with the densities of FoxP3-positive Tregs in respective compartments. Pathological feature analysis showed that densities of ST2-positive cells in the tumor stroma were notably associated with degree of dysplastic grading in patients with adenoma, and disease stages and lymph node metastasis in patients with CRC. Kaplan-Meier survival curves suggested that CRC patients with high densities of ST2-positive cells in the stroma tend to have a shorter overall survival. We therefore concluded that increased densities of ST2-postive cells relate to Treg accumulation within the adenoma/CRC microenvironment, suggesting the IL-33/ST2 pathway as a potential contributor for immunosuppressive milieu formation that impact disease stage and prognosis in patients with CRC.

Expression and secretion of the pro‑inflammatory cytokine IL‑8 is increased in colorectal cancer cells following the knockdown of non‑erythroid spectrin αII

Non‑erythroid spectrin αII (SPTAN1) expression is decreased in ~40% of cases of MLH1‑deficient colorectal cancer (CRC). SPTAN1 knockdown reduces cell viability, cellular mobility and cell‑cell contact formation, indicating that the SPTAN1 plays an important role in tumour growth, attachment and in regulating the tumour microenvironment. Changes in the tumour microenvironment can affect the immune response. Therefore, in the present study, proteome arrays were used to analyse the expression of 119 different chemokines and soluble receptors in CRC cell lines in which mutL homologue 1 (MLH1) or SPTAN1 were knocked down. The levels of interleukin (IL)‑8 were significantly increased in the cells in which SPTAN1 was knocked down, both at the mRNA and protein level. ELISA demonstrated that the cells in which SPTAN1 was knocked down secreted increased quantities of IL‑8, and chemotaxis assays revealed the enhanced trafficking of neutrophils, which was induced by media containing higher levels of IL‑8. The IL‑8 receptors, CRCX1 and CRCX2, were expressed in all the cell lines examined; however, their expression was not directly associated with IL‑8 expression. The results of the present study thus demonstrated that CRC cells in which SPTAN1 was knocked down secreted significantly higher levels of IL‑8, which in‑turn increased the migration of neutrophilic granulocytes. As MLH1‑deficient CRC exhibits an increased infiltration of cytotoxic T‑cells and is associated with a decreased SPTAN1 expression, it can thus be hypothesized that CRC with a low SPTAN1 expression may release increased quantities of IL‑8, resulting in increased immune cell infiltration.

Is Adjuvant Chemotherapy Necessary for Patients with Deficient Mismatch Repair Gastric Cancer?-Autophagy Inhibition Matches the Mismatched

PURPOSE

The use of microsatellite instability (MSI) and mismatch repair (MMR) as predictive biomarkers for fluorouracil-based adjuvant chemotherapy in colorectal cancer has been a paradigm shift. However, whether this applies to gastric cancer is questionable. Furthermore, we herein investigated whether and how autophagy plays a role in MSI-relevant chemoresistance.

MATERIALS AND METHODS

A total of 929 patients with deficient MMR (dMMR) and proficient MMR (pMMR) gastric cancers who underwent curative-intent gastrectomy were enrolled. We compared clinicopathological variables and survival among dMMR and pMMR cohorts and tested the responses of MSI-high and microsatellite stable (MSS) gastric cancer cell lines to 5-fluorouracil (5-FU) with or without chloroquine, an autophagy inhibitor.

RESULTS

We identified an 8.9% prevalence of dMMR cases (83 out of 929) in our cohort. This was associated with old age, tumor site at the distal stomach, an intestinal phenotype, fewer nodal metastasis, and early pathological stages. MMR was an independent prognostic factor after multivariate adjustment. Overall survival (OS) of dMMR patients was better than that of the pMMR patients but was only applicable to stage III patients. There was no difference in OS between dMMR patients treated with or without adjuvant chemotherapy, although the latter showed more medical morbidities. The MSI-high gastric cancer cell lines, versus the MSS counterparts, displayed increased resistance to 5-FU and increased autophagy. Interestingly, autophagy inhibition abrogated the chemoresistance.

CONCLUSION

Our data show that fluorouracil-based adjuvant chemotherapy does not work for dMMR cases, if not worse. Autophagy inhibition and/or immune checkpoint inhibition might be promising alternative strategies for gastric cancer treatment.

IMPLICATIONS FOR PRACTICE

The use of microsatellite instability (MSI) and mismatch repair (MMR) as predictive biomarkers for adjuvant chemotherapy in colorectal cancer has caused a paradigm shift in cancer therapy, although its implications in gastric cancer are still questionable. The data obtained in the current study indicate that MSI-MMR is an independent prognostic factor for gastric cancer. Standard fluorouracil-based adjuvant chemotherapy did not work for deficient MMR cases, and was likely worse. Instead, strategies like autophagy inhibition and/or immune checkpoint inhibition should be taken into consideration in the future.

The Intestinal Tumour Microenvironment

The tumour microenvironment (TME) of intestinal tumours is highly complex and comprises a network of stromal cells, tumour cells, immune cells and fibroblasts, as well as microorganisms. The tumour location, environmental factors and the tumour cells themselves influence the cells within the TME. Immune cells can destroy tumour cells and are associated with better patient prognosis and response to therapy; however, immune cells are highly plastic and easily influenced to instead promote tumour growth. The interaction between local immune cells and the microbiome can lead to progression or regression of intestinal tumours. In this chapter, we will discuss how tumour development and progression can influence, and be influenced by, the microenvironment surrounding it, focusing on immune and fibroblastic cells, and the intestinal microbiota, particularly in the context of colorectal cancer.

Immune checkpoint inhibitors for the treatment of MSI-H/MMR-D colorectal cancer and a perspective on resistance mechanisms

Metastatic colorectal cancer (CRC) with a mismatch repair-deficiency (MMR-D)/microsatellite instability-high (MSI-H) phenotype carries unique characteristics such as increased tumour mutational burden and tumour-infiltrating lymphocytes. Studies have shown a sustained clinical response to immune checkpoint inhibitors with dramatic clinical improvement in patients with MSI-H/MMR-D CRC. However, the observed response rates range between 30% and 50% suggesting the existence of intrinsic resistance mechanisms. Moreover, disease progression after an initial positive response to immune checkpoint inhibitor treatment points to acquired resistance mechanisms. In this review article, we discuss the clinical trials that established the efficacy of immune checkpoint inhibitors in patients with MSI-H/MMR-D CRC, consider biomarkers of the immune response and elaborate on potential mechanisms related to intrinsic and acquired resistance. We also provide a perspective on possible future therapeutic approaches that might improve clinical outcomes, particularly in patients with actionable resistance mechanisms.

A subset of patients with MSS/MSI-low-colorectal cancer showed increased CD8(+) TILs together with up-regulated IFN-γ

A small subset of patients with proficient mismatch repair (pMMR)/microsatellite stable (MSS)-colorectal cancer (CRC) benefit from immunotherapy with anti-programmed cell death 1 (PD-1)/programmed death ligand 1 (PD-L1) blockade. Therefore, the aim of the current study was to evaluate the immune status of patients with pMMR/microsatellite instability-low (MSI-L)/MSS-CRC and deficient MMR (dMMR)/MSI-high (MSI-H)-CRC in order to identify responders to anti-PD-1/PD-L1 inhibitors. The current study used a dataset downloaded from The Cancer Genome Atlas (TCGA) as well as 219 clinical tissue samples to investigate the infiltrating grade of cluster of differentiation (CD) 4 and CD8 tumor infiltrating lymphocytes (TILs), the expression levels of PD-L1 and PD-L2, the interferon-γ (IFN-γ) and CD8 T effector gene signatures, and the phosphorylated signal transducer and activator of transcription 1 (p-STAT1) status in patients with pMMR/MSI-L/MSS-CRC and dMMR/MSI-H-CRC. Analysis of TCGA dataset revealed that the mRNA expression levels of PD-L1 and PD-L2, the IFN-γ gene signature and the CD8 T effector gene signature were significantly upregulated in MSI-H tumors compared with MSI-L/MSS tumors. Additionally, a subpopulation of patients with upregulation of the IFN-γ and CD8 T effector gene signatures was observed in those with MSI-L/MSS-CRC. Immunohistochemical staining of the clinical samples revealed a subpopulation of patients with pMMR-CRC that were positive for PD-L1 and p-STAT1, and whom had levels of elevated CD8(+) and CD4(+) TILs infiltration similar to those observed in patients with dMMR-CRC. The results obtained in the current study suggested that a subpopulation of patients with MSI-L/MSS-CRC and pMMR-CRC with upregulated IFN-γ and CD8 T effector gene signatures may benefit from immunotherapy with antibodies against PD-1 and PD-L1.

Immunological nomograms predicting prognosis and guiding adjuvant chemotherapy in stage II colorectal cancer

BACKGROUND

The type, abundance, and location of tumor-infiltrating lymphocytes (TILs) have been associated with prognosis in colorectal cancer (CRC). This study was conducted to assess the prognostic role of TILs and develop a nomogram for accurate prognostication of stage II CRC.

METHODS

Immunohistochemistry was conducted to assess the densities of intraepithelial and stromal CD3+, CD8+, CD45RO+, and FOXP3+ TILs, and to estimate PD-L1 expression in tumor cells for 168 patients with stage II CRC. The prognostic roles of these features were evaluated using COX regression model, and nomograms were established to stratify patients into low- and high-risk groups and compare the benefit from adjuvant chemotherapy.

RESULTS

In univariate analysis, patients with high intraepithelial or stromal CD3+, CD8+, CD45RO+ and FOXP3+ TILs were associated significantly with better relapse-free survival (RFS) and overall survival (OS), except for stromal CD45RO+ TILs. In multivariate analysis, patients with high intraepithelial CD3+ and stromal FOXP3+ TILs were associated with better RFS (p<0.001 and p=0.032, respectively), while only stromal FOXP3+ TILs was an independent prognostic factor for OS (p=0.031). The nomograms were well calibrated and showed a c-index of 0.751 and 0.757 for RFS and OS, respectively. After stratifying into low- and high-risk groups, the high-risk group exhibited a better OS from adjuvant chemotherapy (3-year OS of 81.9% vs 34.3%, p=0.006).

CONCLUSION

These results may help improve the prognostication of stage II CRC and identify a high-risk subset of patients who appeared to benefit from adjuvant chemotherapy.

Quantitative evaluation of tumor-specific T cells in tumors and lymphoid tissues

Homing of tumor-specific cytotoxic T lymphocytes (CTLs) to the tumor tissues represents a vital step in procuring an effective anti-tumor immune response. Intratumoral accumulation of tumor-specific CTLs can be supported through local chemokine modulation using immune adjuvants or viral vectors, as well as vaccination, using peptide, protein or cell-based vaccines, including dendritic cell (DC) vaccines. Clinical and pre-clinical studies demonstrate that the current immunotherapy regimens are only effective when high numbers of CTLs are present within the tumor microenvironment (TME). Notably, many types of cancer take advantage of this principle and restrict T cell migration into the tumor, subverting the anti-tumor immune response and allowing uncontrolled tumor growth. This chapter discusses the mechanisms involved in the migration of CTLs into tumors and describes the feasible method of evaluating treatment-induced changes in the numbers of polyclonal tumor-specific CTLs in the TME and lymphoid tissues. The described method is widely applicable to multiple tumor models with wild-type antigen expression patterns, without the need for genetically-manipulated cancer cells or animals expressing defined T cell receptors.

Robust and accurate quantification of biomarkers of immune cells in lung cancer micro-environment using deep convolutional neural networks

Recent years have seen a growing awareness of the role the immune system plays in successful cancer treatment, especially in novel therapies like immunotherapy. The characterization of the immunological composition of tumors and their micro-environment is thus becoming a necessity. In this paper we introduce a deep learning-based immune cell detection and quantification method, which is based on supervised learning, i.e., the input data for training comprises labeled images. Our approach objectively deals with staining variation and staining artifacts in immunohistochemically stained lung cancer tissue and is as precise as humans. This is evidenced by the low cell count difference to humans of 0.033 cells on average. This method, which is based on convolutional neural networks, has the potential to provide a new quantitative basis for research on immunotherapy.

Mismatch Repair Status of Gastric Cancer and Its Association with the Local and Systemic Immune Response

BACKGROUND

Microsatellite instability (MSI)-high (MSI-H) colorectal cancer is known to be associated with increased tumor-infiltrating lymphocytes (TILs), elevated host systemic immune response, and a favorable prognosis. In gastric cancer, however, MSI status has rarely been evaluated in the context of TILs and systemic immune response.

MATERIALS AND METHODS

We evaluated data for 345 patients with gastric cancer who underwent gastrectomy with MSI typing. The numbers of TILs were counted after immunohistochemical staining with anti-CD3, CD4, CD8, forkhead box P3 (Foxp3), and granzyme B to quantify the subsets of TILs. To evaluate the systemic immune response, the differential white blood cell count and prognostic nutritional index (PNI) were obtained.

RESULTS

Of the 345 patients, 57 demonstrated MSI-H tumors and 288 demonstrated non-MSI-H tumors. MSI-H tumors carried significantly higher densities of CD8+ T cells, Foxp3+ T cells, and granzyme B+ T cells and a higher ratio of Foxp3/CD4 and granzyme B/CD8. The prognostic impact of TILs differed between patients with MSI-H tumors and those with non-MSI-H tumors. The TIL subsets were not found to be significant prognostic factors for recurrence-free survival (RFS) or overall survival (OS) in the MSI-H tumor group. In the non-MSI-H tumor group, multivariate analysis showed that stage, PNI, and CD4+ T cells were independent prognostic factors for RFS, and stage, PNI, and the Foxp3/CD4 ratio were independent prognostic factors for OS.

CONCLUSIONS

The association between systemic/local immune response and prognosis differed according to MSI status. Different tumor characteristics and prognoses according to MSI status could be associated with the immunogenicity caused by microsatellite instability and subsequent host immune response.

IMPLICATIONS FOR PRACTICE

This study demonstrates that the density of each subset of tumor-infiltrating lymphocytes (TILs) differed between microsatellite instability (MSI)-high and non-MSI-high tumors. Moreover, the prognostic effect of the preoperative systemic immune response status and TILs differed between the MSI-high (MSI-H) and non-MSI-H tumor groups. The present study may help to identify the mechanisms of cancer progression and develop treatment strategies for MSI-high gastric cancer.

Integrative analysis identifies DNMTs against immune-infiltrating neutrophils and dendritic cells in colorectal cancer

Molecular characterizations, including microsatellite instability (MSI) and the CpG island methylator phenotype (CIMP) showed strong associations in colorectal carcinoma (CRC) and provided a deeper understanding of the etiology of disease. However, the global relationship between epigenetic alternations and changes in mRNA expression in CRC remains largely undefined, especially regarding the roles of DNA methyltransferases (DNMTs). Here, we conducted a systematic network comparison to explore the global conservation between co-expressed and co-methylated modules. We successfully identified immune-related modules that were regulated by DNMTs and had strong associations with immune-infiltrating neutrophils and dendritic cells in CRC. Moreover, we found that genes in those modules were prognostic for CRC, with 97.1% (168/173) being significantly influenced by DNMTs. Thus, this study resolved an interaction between DNA methylation and mRNA expression through DNMTs. Additionally, we provided evidence that DNMTs control the global hypomethylation of oncogenes, including ALOX5AP and CSF3R that otherwise have high methylation in normal colons. Such genes were also more sensitive to DNMT changes, such as in CRC. Collectively, our analyzes provided a systems biology approach to investigate the association among different molecular phenotypes in diseases.

Physical plasma-treated saline promotes an immunogenic phenotype in CT26 colon cancer cells in vitro and in vivo

Metastatic colorectal cancer is the fourth most common cause of cancer death. Current options in palliation such as hyperthermic intraperitoneal chemotherapy (HIPEC) present severe side effects. Recent research efforts suggested the therapeutic use of oxidant-enriched liquid using cold physical plasma. To investigate a clinically accepted treatment regimen, we assessed the antitumor capacity of plasma-treated saline solution. In response to such liquid, CT26 murine colon cancer cells were readily oxidized and showed cell growth with subsequent apoptosis, cell cycle arrest, and upregulation of immunogenic cell death (ICD) markers in vitro. This was accompanied by marked morphological changes with re-arrangement of actin fibers and reduced motility. Induction of an epithelial-to-mesenchymal transition phenotype was not observed. Key results were confirmed in MC38 colon and PDA6606 pancreatic cancer cells. Compared to plasma-treated saline, hydrogen peroxide was inferiorly toxic in 3D tumor spheroids but of similar efficacy in 2D models. In vivo, plasma-treated saline decreased tumor burden in Balb/C mice. This was concomitant with elevated numbers of intratumoral macrophages and increased T cell activation following incubation with CT26 cells ex vivo. Being a potential adjuvant for HIPEC therapy, our results suggest oxidizing saline solutions to inactivate colon cancer cells while potentially stimulating antitumor immune responses.

Multiparametric analysis of colorectal cancer immune responses

Colorectal cancer (CRC) is a heterogeneous disease, with a diverse and plastic immune cell infiltrate. These immune cells play an important role in regulating tumour growth - progression or elimination. Some populations of cells have a strong correlation with disease-free survival, making them useful prognostic markers. In particular, the infiltrate of CD3+ and CD8+ T cells into CRC tumours has been validated worldwide as a valuable indicator of patient prognosis. However, the heterogeneity of the immune response, both between patients with tumours of different molecular subtypes, and within the tumour itself, necessitates the use of multiparametric analysis in the investigation of tumour-specific immune responses. This review will outline the multiparametric analysis techniques that have been developed and applied to studying the role of immune cells in the tumour, with a focus on colorectal cancer. Because much of the data in this disease relates to T cell subsets and heterogeneity, we have used T cell populations as examples throughout. Flow and mass cytometry give a detailed representation of the cells within the tumour in a single-cell suspension on a per-cell basis. Imaging technologies, such as imaging mass cytometry, are used to investigate increasing numbers of markers whilst retaining the spatial and structural information of the tumour section and the infiltrating immune cells. Together, the analyses of multiple immune parameters can provide valuable information to guide clinical decision-making in CRC.

Regulatory T cells control endothelial chemokine production and migration of T cells into intestinal tumors of APCmin/+ mice

Tumor-infiltrating lymphocytes are crucial for anti-tumor immunity. We have previously shown that regulatory T cells (Treg) are able to reduce T-cell transendothelial migration in vitro and accumulation of effector T cells in intestinal tumors in vivo. Treg depletion also resulted in increased levels of the chemokines CXCL9 and CXCL10 specifically in the tumors. In this study, we investigated the mechanisms for Treg mediated suppression of T-cell migration into intestinal tumors in the APCmin/+ mouse model. By breeding APCmin/+ mice with DEREG mice, which harbour a high affinity diphtheria toxin receptor under the control of the FOXP3 promoter, we were able to deplete Treg in tumor-bearing mice. Using adoptive transfer experiments, we could document a markedly increased migration of T cells specifically into Treg depleted tumors, and that Treg depletion results in increased production of the CXCR3 ligand CXCL10 from endothelial cells in the tumors. Furthermore, we were able to demonstrate that T cells use CXCR3 to migrate into intestinal tumors. In addition, human colon adenocarcinomas express high levels of mRNA CXCR3 ligands and tumor endothelial cells produce CXCL9 and CXCL10 ex vivo. In conclusion, this study demonstrates that Treg reduce endothelial CXCL10 production, inhibit T-cell migration into tumors and that CXCR3 mediated signalling is crucial for lymphocyte accumulation in intestinal tumors. Thus, immunotherapy aimed at Treg depletion may be effective by increasing not only T effector cell activity, but also their accumulation in tumors.

Checkpoints and beyond - Immunotherapy in colorectal cancer

Immunotherapy is the latest revolution in cancer therapy. It continues to show impressive results in malignancies like melanoma and others. At least so far, effects are modest in colorectal cancer (CRC) and only a subset of patients benefits from already approved checkpoint inhibitors. In this review, we discuss major hurdles of immunotherapy like the immunosuppressive niche and low immunogenicity of CRC next to current achievements of checkpoint inhibitors, interleukin treatment and adoptive cell transfer (dendritic cells/cytokine induced killer cells, tumor infiltrating lymphocytes, chimeric antigen receptor cells, T cell receptor transfer) in pre-clinical models and clinical trials. We intensively examine approaches to overcome low immunogenicity by combination of different therapies and address future strategies of therapy as well as the need of predictive factors in this emerging field of precision medicine.

Expression of PD-L1, indoleamine 2,3-dioxygenase and the immune microenvironment in gastric adenocarcinoma

AIMS

The tumour microenvironment is increasingly important in several tumours. We studied the relationship of key players of immune microenvironment with clinicopathological parameters in gastric adenocarcinomas.

METHODS AND RESULTS

Tissue microarrays were constructed from gastrectomy specimens, 2004-13. Immunohistochemistry was performed for programmed cell death ligand 1 (PD-L1), indoleamine 2,3-dioxygenase (IDO), tryptophanyl-tRNA synthetase (WARS), guanylate-binding protein 5 (GBP5), tumour-infiltrating lymphocytes (TIL) expressing CD3/CD8/FoxP3/PD1 and mismatch repair proteins (MMRs) MLH1, PMS2, MSH2 and MSH6. Clinicopathological parameters and clinical follow-up were recorded. The study included 86 patients; median follow-up was 34 months (0-148). Tumour types were 45% tubular, 38% diffuse, 17% mixed. PD-L1 was positive in 70%, epithelial IDO in 58%, stromal IDO in 91%, epithelial WARS in 67%, stromal WARS in 100%, epithelial GBP5 in 53% and stromal GBP5 in 71%. MMR-deficiency was found in 22%. There was no difference in biomarker expression by histological subtype, with the exception of fewer diffuse-type being MMR-deficient. Low stromal IDO was associated with decreased progression-free, overall and disease-specific survival. PD-L1-positive tumours were larger with MMR-deficiency and with increasing TILs, and had significantly higher FoxP3TILs.

CONCLUSIONS

PD-L1 is expressed in a large proportion of gastric carcinomas, suggesting that therapy targeting this pathway could be relevant to many patients. PD-L1 expression and MMR-deficiency are associated with increased TILs and larger tumour size, emphasising their role in tumour biology. Higher stromal IDO expression is associated with better prognosis. Finally, we observed that immune modulators WARS and GBP5 are expressed highly in gastric adenocarcinomas, suggesting an important role in tumour pathobiology.

Elevated level of interleukin-35 in colorectal cancer induces conversion of T cells into iTr35 by activating STAT1/STAT3

IL-35 is a novel heterodimeric and inhibitory cytokine, composed of interleukin-12 subunit alpha (P35) and Epstein-Barr virus -induced gene 3 (EBI3). IL-35 has been reported to be produced by a range of cell types, especially regulatory T cells, and to exert immunosuppressive effects via the STATx signaling pathway. In this study, we demonstrated that IL-35 expression was elevated in both serum and tumors in patients with colorectal cancer. IL-35 mainly expressed in CD4⁺ T cells in human colorectal cancer tumors and adjacent tissues. Increased IL-35 expression in tumor-adjacent tissues was significantly associated with tumor metastasis. IL-35 inhibited the proliferation of CD4⁺CD25⁻ T effector cells in vitro in a dose-dependent manner, and its suppression was partially reversed by applying IL-35-neutralizing antibodies. IL-35 treatment activated the phosphorylation of both STAT1 and STAT3 in human CD4⁺ T cells. Meanwhile, IL-35 induced a positive feedback loop to promote its own production. We observed that Tregs obtained from colorectal cancer patients were capable of inducing more IL-35 production. In addition, EBI3 promoter-driven luciferase activity was higher than that of the mock plasmid after IL-35stimulation. Thus, our study indicates that the high level of IL-35 in colorectal cancer promotes the production of IL-35 via STAT1 and STAT3, which suppresses T cell proliferation and may participate in tumor immunotolerance.

Tumour-infiltrating regulatory T cell density before neoadjuvant chemoradiotherapy for rectal cancer does not predict treatment response

Neoadjuvant (preoperative) chemoradiotherapy (CRT) decreases the risk of rectal cancer recurrence and reduces tumour volume prior to surgery. However, response to CRT varies considerably between individuals and factors associated with response are poorly understood. Foxp3+ regulatory T cells (Tregs) inhibit anti-tumour immunity and may limit any response to chemotherapy and radiotherapy. We have previously reported that a low density of Tregs in the tumour stroma following neoadjuvant CRT for rectal cancer is associated with improved tumour regression. Here we have examined the association between Treg density in pre-treatment diagnostic biopsy specimens and treatment response, in this same patient cohort. We aimed to determine whether pre-treatment tumour-infiltrating Treg density predicts subsequent response to neoadjuvant CRT. Foxp3+, CD8+ and CD3+ cell densities in biopsy samples from 106 patients were assessed by standard immunohistochemistry (IHC) and evaluated for their association with tumour regression grade and survival. We found no association between the density of any T cell subset pre-treatment and clinical outcome, indicating that tumour-infiltrating Treg density does not predict response to neoadjuvant CRT in rectal cancer. Taken together with the findings of the previous study, these data suggest that in the context of neoadjuvant CRT for rectal cancer, the impact of chemotherapy and/or radiotherapy on anti-tumour immunity may be more important than the state of the pre-existing local immune response.

Immunotherapy holds the key to cancer treatment and prevention in constitutional mismatch repair deficiency (CMMRD) syndrome

Monoallelic germline mutations in one of the DNA mismatch repair (MMR) genes cause Lynch syndrome, with a high lifetime risks of colorectal and endometrial cancer at adult age. Less well known, is the constitutional mismatch repair deficiency (CMMRD) syndrome caused by biallelic germline mutations in MMR genes. This syndrome is characterized by the development of childhood cancer. Patients with CMMRD are at extremely high risk of developing multiple cancers including hematological, brain and intestinal tumors. Mutations in MMR genes impair DNA repair and therefore most tumors of patients with CMMRD are hypermutated. These mutations lead to changes in the translational reading frame, which consequently result in neoantigen formation. Neoantigens are recognized as foreign by the immune system and can induce specific immune responses. The growing evidence on the clinical efficacy of immunotherapies, such as immune checkpoint inhibitors, offers the prospect for treatment of patients with CMMRD. Combining neoantigen-based vaccination strategies and immune checkpoint inhibitors could be an effective way to conquer CMMRD-related tumors. Neoantigen-based vaccines might also be a preventive treatment option in healthy biallelic MMR mutation carriers. Future studies need to reveal the safety and efficacy of immunotherapies for patients with CMMRD.

Tumor-Associated Macrophages and Regulatory T Cells Infiltration and the Clinical Outcome in Colorectal Cancer

The aim of the study is the assessment of the intensity of the infiltration of tumor-associated macrophages (TAMs) CD68⁺/iNOS⁻ and Tregs CD8⁺/FoxP3⁺ in colorectal cancer (CRC) patients as prognostic factors with respect to disease-free survival (DFS) and overall survival (OS). In this retrospective study, tissue samples were obtained from 89 patients undergoing resection for CRC (stage IIA, pT3N0M0 and stages IIIB and IIIC, pT3N1-2M0). Recurrence was observed in 45 patients at the time of the follow-up (10 local recurrences, 35 distant metastases). In patients with recurrence the following were present: a tendency to an older average age at the time of diagnosis (p = 0.07), higher nodal involvement (p = 0.002) and more advanced clinical disease (p = 0.01). The analysis of the clinical data and immunohistochemical studies were performed with the methodology of identification of TAM and Treg subsets in histological sections, with the aim to use it in routine clinical management. Both DSF and OS were the clinical parameters assessed in the study. The presence of intense infiltration of TAMs in the tumor stroma was related to shorter DFS (p = 0.005) and OS (p = 0.006). The opposite tendency was observed in the tumor front (p = 0.061). The relative risks of recurrence and cancer-related death were more than twice higher in the group of patients with intense infiltration of TAMs in the tumor stroma (RR 2.05, 95% CI 1.33–3.14; p = 0.001 and RR 2.08, 95% CI 1.28–3.39; p = 0.003, respectively). Intense infiltration of Tregs in the tumor stroma was related to shorter DFS and OS (p < 0.0001). The relative risks of recurrence and death in a group of patients with intense infiltration of Tregs in the tumor stroma were more than 12 times higher than in patients with less intense infiltration (RR 12.3, 95% CI 5.44–27.9; p < 0.0001 and RR 12.5, 95% CI 4.9–32.4; p < 0.0001, respectively). Infiltration of TAMs CD68⁺/iNOS⁻ and Tregs CD8⁺/FoxP3⁺ in the tumor stroma are negative prognostic factors with a positive correlation between them. Tregs may constitute an independent prognostic factor in patients with CRC.

Marine ω-3 Polyunsaturated Fatty Acid Intake and Risk of Colorectal Cancer Characterized by Tumor-Infiltrating T Cells

IMPORTANCE

Marine ω-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid, possess potent immunomodulatory activity and may protect against cancer development. However, evidence relating marine ω-3 PUFAs to colorectal cancer (CRC) risk remains inconclusive.

OBJECTIVE

To test the hypothesis that marine ω-3 PUFA intake may be associated with lower risk of CRC subsets characterized by immune infiltrate.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted among participants in the Nurses' Health Study (1984-2010) and Health Professionals Follow-up Study (1986-2010).

EXPOSURES

Intake of marine ω-3 PUFAs.

MAIN OUTCOMES AND MEASURES

Incidence of CRC characterized by CD3+, CD8+, CD45RO (PTPRC)+, or FOXP3+ T-cell densities in tumor tissue, measured by immunohistochemical and computer-assisted image analysis.

RESULTS

Among 173 229 predominantly white participants, 125 172 with 2 895 704 person-years of follow-up provided data about marine ω-3 PUFA intake every 4 years through a validated food frequency questionnaire and followed up for incident CRC evaluation. Of 2504 CRC cases, we documented 614 (252 men, 362 women) from which we could assess T-cell infiltration in the tumor microenvironment. The inverse association of marine ω-3 PUFAs intake with CRC risk differed according to FOXP3+ T-cell infiltration: compared with intake of less than 0.15 g/d of marine ω-3 PUFAs, intake of at least 0.35 g/d was associated with a multivariable hazard ratio (HR) of 0.57 (95% CI, 0.40-0.81; P < .001 for trend) for FOXP3+ T-cell-high tumors. In contrast, the HR for FOXP3+ T-cell-low tumors was 1.14 (95% CI, 0.8-1.60) (P = .77 for trend; P = .01 for heterogeneity). No statistically significant differential association was found for high-density tumors (compared with low-density tumors) according to CD3+, CD8+, or CD45RO+ cell density (P ≥ .34 for heterogeneity for all comparisons). In functional assays, the suppressive activity of regulatory T cells was approximately 2-fold lower (T-effector-cell proliferation, ≥64% vs 38%) when preincubated with docosahexaenoic acid at 50μM, 100μM, and 200μM concentrations than without docosahexaenoic acid (P < .001 for all comparisons).

CONCLUSIONS AND RELEVANCE

High marine ω-3 PUFA intake was associated with lower risk of CRC with high-level, but not low-level, FOXP3+ T-cell density, suggesting a potential role of ω-3 PUFAs in cancer immunoprevention through modulation of regulatory T cells.

Tumor Immuno-Environment in Cancer Progression and Therapy

The approvals of Provenge (Sipuleucel-T), Ipilimumab (Yervoy/anti-CTLA-4) and blockers of the PD-1 - PD-L1/PD-L2 pathway, such as nivolumab (Opdivo), pembrolizumab (Keytruda), or atezolizumab (Tecentriq), have established immunotherapy as a key component of comprehensive cancer care. Further, murine mechanistic studies and studies in immunocompromised patients have documented the critical role of immunity in effectiveness of radio- and chemotherapy. However, in addition to the ability of the immune system to control cancer progression, it can also promote tumor growth, via regulatory T cells (Tregs), myeloid-derived dendritic cells (MDSCs) and tumor associated macrophages (TAM), which can enhance survival of cancer cells directly or via the regulation of the tumor stroma.An increasing body of evidence supports a central role for the tumor microenvironment (TME) and the interactions between tumor stroma, infiltrating immune cells and cancer cells during the induction and effector phase of anti-cancer immunity, and the overall effectiveness of immunotherapy and other forms of cancer treatment. In this chapter, we discuss the roles of key TME components during tumor progression, metastatic process and cancer therapy-induced tumor regression, as well as opportunities for their modulation to enhance the overall therapeutic benefit.

Functional reprogramming of human prostate cancer to promote local attraction of effector CD8(+) T cells

BACKGROUND

Local infiltration of CD8(+) T cells (CTLs) in tumor lesions predicts overall clinical outcomes and the clinical benefit of cancer patients from immune checkpoint blockade. In the current study, we evaluated local production of different classes of chemokines in prostate cancer lesions, and the feasibility of their modulation to promote selective entry of CTLs into prostate tumors.

METHODS

Chemokine expression in prostate cancer lesion was analyzed by TaqMan-based quantitative PCR, confocal fluorescence microscopy and ELISA. For ex vivo chemokine modulation analysis, prostate tumor explants from patients undergoing primary prostate cancer resections were cultured for 24 hr, in the absence or presence of the combination of poly-I:C, IFNα, and celecoxib (PAC). The numbers of cells producing defined chemokines in the tissues were analyzed by confocal microscopy. Chemotaxis of effector CD8(+) T cells towards the untreated and PAC-treated tumor explant supernatants were evaluated in a standard in vitro migration assays, using 24 well trans-well plates. The number of effector cells that migrated was enumerated by flow cytometry. Pearson (r) correlation was used for analyzing correlations between chemokines and immune filtrate, while paired two tailed students t-test was used for comparison between treatment groups.

RESULTS

Prostate tumors showed uniformly low levels of CTL/NK/Th1-recruiting chemokines (CCL5, CXCL9, CXCL10) but expressed high levels of chemokines implicated in the attraction of myeloid derived suppressor cells (MDSC) and regulatory T cells (Treg ): CCL2, CCL22, and CXCL12. Strong positive correlations were observed between CXCL9 and CXCL10 and local CD8 expression. Tumor expression levels of CCL2, CCL22, and CXCL12 were correlated with intratumoral expression of MDSC/Treg markers: FOXP3, CD33, and NCF2. Treatment with PAC suppressed intratumoral production of the Treg -attractant CCL22 and Treg /MDSC-attractant, CXCL12, while increasing the production of the CTL attractant, CXCL10. These changes in local chemokine production were accompanied by the reduced ability of the ex vivo-treated tumors to attract CD4(+) FOXP3(+) Treg cells, and strongly enhanced attraction of the CD8(+) Granzyme B(+) CTLs.

CONCLUSIONS

Our data demonstrate that the chemokine environment in prostate cancer can be reprogrammed to selectively enhance the attraction of type-1 effector immune cells and reduce local attraction of MDSCs and Tregs . Prostate 76:1095-1105, 2016. © 2016 Wiley Periodicals, Inc.

Heme oxygenase-1 promotes tumor progression and metastasis of colorectal carcinoma cells by inhibiting antitumor immunity

Heme oxygenase-1 (HO-1) is upregulated in colorectal carcinoma (CRC) cells. However, the role of HO-1 in the metastatic potential of CRC remains to be elucidated. In this study, we investigated the potential of HO-1 to control the antitumor immunity of CRC. Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the immune surveillance system. Hemin-induced HO-1 expression suppressed the expression of ICAM-1 in human CRC cells. HO-1 regulated ICAM-1 expression via tristetraprolin, an mRNA-binding protein, at the posttranscriptional level in CRC cells. The upregulated HO-1 expression in CRC cells markedly decreased the adhesion of peripheral blood mononuclear lymphocytes (PBMLs) to CRC cells and PBML-mediated cytotoxicity against CRC cells. Production of CXCL10, an effector T cell-recruiting chemokine, was significantly reduced by the increased HO-1 expression. The expression of the CXCL10 receptor, CXCR3, decreased significantly in PBMLs that adhered to CRC cells. HO-1 expression correlated negatively, although nonsignificantly, with ICAM-1 and CXCL10 expression in xenograft tumors. Taken together, our data suggest that HO-1 expression is functionally linked to the mediation of tumor progression and metastasis of CRC cells by inhibiting antitumor immunity.

Rational bases for the use of the Immunoscore in routine clinical settings as a prognostic and predictive biomarker in cancer patients

The American Joint Committee on Cancer/Union Internationale Contre le Cancer (AJCC/UICC) tumor, nodes, metastasis (TNM) classification system based on tumor features is used for prognosis estimation and treatment recommendations in most cancers. However, the clinical outcome can vary significantly among patients within the same tumor stage and TNM classification does not predict response to therapy. Therefore, many efforts have been focused on the identification of new markers. Multiple tumor cell-based approaches have been proposed but very few have been translated into the clinic. The recent demonstration of the essential role of the immune system in tumor progression has allowed great advances in the understanding of this complex disease and in the design of novel therapies. The analysis of the immune infiltrate by imaging techniques in large patient cohorts highlighted the prognostic impact of the in situ immune cell infiltrate in tumors. Moreover, the characterization of the immune infiltrates (e.g. type, density, distribution within the tumor, phenotype, activation status) in patients treated with checkpoint-blockade strategies could provide information to predict the disease outcome. In colorectal cancer, we have developed a prognostic score ('Immunoscore') that takes into account the distribution of the density of both CD3(+) lymphocytes and CD8(+) cytotoxic T cells in the tumor core and the invasive margin that could outperform TNM staging. Currently, an international retrospective study is under way to validate the Immunoscore prognostic performance in patients with colon cancer. The use of Immunoscore in clinical practice could improve the patients' prognostic assessment and therapeutic management.