Tumor-associated macrophages and response to 5-fluorouracil adjuvant therapy in stage III colorectal cancer

Targeting of TAMs: can we be more clever than cancer cells?

АBSTRACT: With increasing incidence and geography, cancer is one of the leading causes of death, reduced quality of life and disability worldwide. Principal progress in the development of new anticancer therapies, in improving the efficiency of immunotherapeutic tools, and in the personification of conventional therapies needs to consider cancer-specific and patient-specific programming of innate immunity. Intratumoral TAMs and their precursors, resident macrophages and monocytes, are principal regulators of tumor progression and therapy resistance. Our review summarizes the accumulated evidence for the subpopulations of TAMs and their increasing number of biomarkers, indicating their predictive value for the clinical parameters of carcinogenesis and therapy resistance, with a focus on solid cancers of non-infectious etiology. We present the state-of-the-art knowledge about the tumor-supporting functions of TAMs at all stages of tumor progression and highlight biomarkers, recently identified by single-cell and spatial analytical methods, that discriminate between tumor-promoting and tumor-inhibiting TAMs, where both subtypes express a combination of prototype M1 and M2 genes. Our review focuses on novel mechanisms involved in the crosstalk among epigenetic, signaling, transcriptional and metabolic pathways in TAMs. Particular attention has been given to the recently identified link between cancer cell metabolism and the epigenetic programming of TAMs by histone lactylation, which can be responsible for the unlimited protumoral programming of TAMs. Finally, we explain how TAMs interfere with currently used anticancer therapeutics and summarize the most advanced data from clinical trials, which we divide into four categories: inhibition of TAM survival and differentiation, inhibition of monocyte/TAM recruitment into tumors, functional reprogramming of TAMs, and genetic enhancement of macrophages.

How to Use Macrophages Against Cancer

Numerous studies have demonstrated the significant influence of immune cells on cancer development and treatment. This study specifically examines tumor-associated macrophages (TAMs), detailing their characteristics and roles in tumorigenesis and analyzing the impact of the ratio of TAM subtypes on patient survival and prognosis. It is established that TAMs interact with immunotherapy, radiotherapy, and chemotherapy, thereby influencing the efficacy of these treatments. Emerging therapies are explored, such as the use of nanoparticles (NPs) for drug delivery to target TAMs and modify the tumor microenvironment (TME). Additionally, novel anticancer strategies like the use of chimeric antigen receptor macrophages (CAR-Ms) show promising results. Investigations into the training of macrophages using magnetic fields, plasma stimulation, and electroporation are also discussed. Finally, this study presents prospects for the combination of TAM-based therapies for enhanced cancer treatment outcomes.

Tumor-associated macrophages: A sentinel of innate immune system in tumor microenvironment gone haywire

The tumor microenvironment (TME) is a critical determinant in the initiation, progression, and treatment outcomes of various cancers. Comprising of cancer-associated fibroblasts (CAF), immune cells, blood vessels, and signaling molecules, the TME is often likened to the soil supporting the seed (tumor). Among its constituents, tumor-associated macrophages (TAMs) play a pivotal role, exhibiting a dual nature as both promoters and inhibitors of tumor growth. This review explores the intricate relationship between TAMs and the TME, emphasizing their diverse functions, from phagocytosis and tissue repair to modulating immune responses. The plasticity of TAMs is highlighted, showcasing their ability to adopt either protumorigenic or anti-tumorigenic phenotypes based on environmental cues. In the context of cancer, TAMs' pro-tumorigenic activities include promoting angiogenesis, inhibiting immune responses, and fostering metastasis. The manuscript delves into therapeutic strategies targeting TAMs, emphasizing the challenges faced in depleting or inhibiting TAMs due to their multifaceted roles. The focus shifts towards reprogramming TAMs to an anti-tumorigenic M1-like phenotype, exploring interventions such as interferons, immune checkpoint inhibitors, and small molecule modulators. Noteworthy advancements include the use of CSF1R inhibitors, CD40 agonists, and CD47 blockade, demonstrating promising results in preclinical and clinical settings. A significant section is dedicated to Chimeric Antigen Receptor (CAR) technology in macrophages (CAR-M cells). While CAR-T cells have shown success in hematological malignancies, their efficacy in solid tumors has been limited. CAR-M cells, engineered to infiltrate solid tumors, are presented as a potential breakthrough, with a focus on their development, challenges, and promising outcomes. The manuscript concludes with the exploration of third-generation CAR-M technology, offering insight into in-vivo reprogramming and nonviral vector approaches. In conclusion, understanding the complex and dynamic role of TAMs in cancer is crucial for developing effective therapeutic strategies. While early-stage TAM-targeted therapies show promise, further extensive research and larger clinical trials are warranted to optimize their targeting and improve overall cancer treatment outcomes.

Clinical landscape of macrophage-reprogramming cancer immunotherapies

Tumour-associated macrophages (TAMs) sustain a tumour-supporting and immunosuppressive milieu and therefore aggravate cancer prognosis. To modify TAM behaviour and unlock their anti-tumoural potential, novel TAM-reprogramming immunotherapies are being developed at an accelerating rate. At the same time, scientific discoveries have highlighted more sophisticated TAM phenotypes with complex biological functions and contradictory prognostic associations. To understand the evolving clinical landscape, we reviewed current and past clinically evaluated TAM-reprogramming cancer therapeutics and summarised almost 200 TAM-reprogramming agents investigated in more than 700 clinical trials. Observable overall trends include a high frequency of overlapping strategies against the same therapeutic targets, development of more complex strategies to improve previously ineffective approaches and reliance on combinatory strategies for efficacy. However, strong anti-tumour efficacy is uncommon, which encourages re-directing efforts on identifying biomarkers for eligible patient populations and comparing similar treatments earlier. Future endeavours will benefit from considering the shortcomings of past treatment strategies and accommodating the emerging complexity of TAM biology.

THP-1 Monocytic Cells Are Polarized to More Antitumorigenic Macrophages by Serial Treatment with Phorbol-12-Myristate-13-Acetate and PD98059

Background and Objectives: As modulators of the tumor microenvironment, macrophages have been extensively studied for their potential in developing anticancer strategies, particularly in regulating macrophage polarization towards an antitumorigenic (M1) phenotype rather than a protumorigenic (M2) one in various experimental models. Here, we evaluated the effect of PD98059, a mitogen-activated protein kinase kinase MAPKK MEK1-linked pathway inhibitor, on the differentiation and polarization of THP-1 monocytes in response to phorbol-12-myristate-13-acetate (PMA) under various culture conditions for tumor microenvironmental application. Materials and Methods: Differentiation and polarization of THP-1 were analyzed by flow cytometry and RT-PCR. Polarized THP-1 subsets with different treatment were compared by motility, phagocytosis, and so on. Results: Clearly, PMA induced THP-1 differentiation occurs in adherent culture conditions more than nonadherent culture conditions by increasing CD11b expression up to 90%, which was not affected by PD98059 when cells were exposed to PMA first (post-PD) but inhibited when PD98059 was treated prior to PMA treatment (pre-PD). CD11bhigh THP-1 cells treated with PMA and PMA-post-PD were categorized into M0 (HLA-DRlow and CD206low), M1 (HLA-DRhigh and CD206low), and M2 (HLA-DRlow and CD206high), resulting in an increased population of M1 macrophages. The transcription levels of markers of macrophage differentiation and polarization confirmed the increased M1 polarization of THP-1 cells with post-PD treatment rather than with PMA-only treatment. The motility and cytotoxicity of THP-1 cells with post-PD treatment were higher than THP-1 cells with PMA, suggesting that post-PD treatment enhanced the anti-tumorigenicity of THP-1 cells. Confocal microscopy and flow cytometry showed the effect of post-PD treatment on phagocytosis by THP-1 cells. Conclusions: We have developed an experimental model of macrophage polarization with THP-1 cells which will be useful for further studies related to the tumor microenvironment.

Potential therapeutic targets in myeloid cell therapy for overcoming chemoresistance and immune suppression in gastrointestinal tumors

In the tumor microenvironment (TME), myeloid cells play a pivotal role. Myeloid-derived immunosuppressive cells, including tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), are central components in shaping the immunosuppressive milieu of the tumor. Within the TME, a majority of TAMs assume an M2 phenotype, characterized by their pro-tumoral activity. These cells promote tumor cell growth, angiogenesis, invasion, and migration. In contrast, M1 macrophages, under appropriate activation conditions, exhibit cytotoxic capabilities against cancer cells. However, an excessive M1 response may lead to pro-tumoral inflammation. As a result, myeloid cells have emerged as crucial targets in cancer therapy. This review concentrates on gastrointestinal tumors, detailing methods for targeting macrophages to enhance tumor radiotherapy and immunotherapy sensitivity. We specifically delve into monocytes and tumor-associated macrophages' various functions, establishing an immunosuppressive microenvironment, promoting tumorigenic inflammation, and fostering neovascularization and stromal remodeling. Additionally, we examine combination therapeutic strategies.

Immune cell networking in solid tumors: focus on macrophages and neutrophils

The tumor microenvironment is composed of tumor cells, stromal cells and leukocytes, including innate and adaptive immune cells, and represents an ecological niche that regulates tumor development and progression. In general, inflammatory cells are considered to contribute to tumor progression through various mechanisms, including the formation of an immunosuppressive microenvironment. Macrophages and neutrophils are important components of the tumor microenvironment and can act as a double-edged sword, promoting or inhibiting the development of the tumor. Targeting of the immune system is emerging as an important therapeutic strategy for cancer patients. However, the efficacy of the various immunotherapies available is still limited. Given the crucial importance of the crosstalk between macrophages and neutrophils and other immune cells in the formation of the anti-tumor immune response, targeting these interactions may represent a promising therapeutic approach against cancer. Here we will review the current knowledge of the role played by macrophages and neutrophils in cancer, focusing on their interaction with other immune cells.

Tumor-associated macrophages in colorectal cancer metastasis: molecular insights and translational perspectives

Metastasis is the leading cause of high mortality in colorectal cancer (CRC), which is not only driven by changes occurring within the tumor cells, but is also influenced by the dynamic interaction between cancer cells and components in the tumor microenvironment (TME). Currently, the exploration of TME remodeling and its impact on CRC metastasis has attracted increasing attention owing to its potential to uncover novel therapeutic avenues. Noteworthy, emerging studies suggested that tumor-associated macrophages (TAMs) within the TME played important roles in CRC metastasis by secreting a variety of cytokines, chemokines, growth factors and proteases. Moreover, TAMs are often associated with poor prognosis and drug resistance, making them promising targets for CRC therapy. Given the prognostic and clinical value of TAMs, this review provides an updated overview on the origin, polarization and function of TAMs, and discusses the mechanisms by which TAMs promote the metastatic cascade of CRC. Potential TAM-targeting techniques for personalized theranostics of metastatic CRC are emphasized. Finally, future perspectives and challenges for translational applications of TAMs in CRC development and metastasis are proposed to help develop novel TAM-based strategies for CRC precision medicine and holistic healthcare.

Immunogenic chemotherapy: great potential for improving response rates

The activation of anti-tumor immunity is critical in treating cancers. Recent studies indicate that several chemotherapy agents can stimulate anti-tumor immunity by inducing immunogenic cell death and durably eradicate tumors. This suggests that immunogenic chemotherapy holds great potential for improving response rates. However, chemotherapy in practice has only had limited success in inducing long-term survival or cure of cancers when used either alone or in combination with immunotherapy. We think that this is because the importance of dose, schedule, and tumor model dependence of chemotherapy-activated anti-tumor immunity is under-appreciated. Here, we review immune modulation function of representative chemotherapy agents and propose a model of immunogenic chemotherapy-induced long-lasting responses that rely on synergetic interaction between killing tumor cells and inducing anti-tumor immunity. We comb through several chemotherapy treatment schedules, and identify the needs for chemotherapy dose and schedule optimization and combination therapy with immunotherapy when chemotherapy dosage or immune responsiveness is too low. We further review tumor cell intrinsic factors that affect the optimal chemotherapy dose and schedule. Lastly, we review the biomarkers indicating responsiveness to chemotherapy and/or immunotherapy treatments. A deep understanding of how chemotherapy activates anti-tumor immunity and how to monitor its responsiveness can lead to the development of more effective chemotherapy or chemo-immunotherapy, thereby improving the efficacy of cancer treatment.

Jin-Fu-An decoction manipulation of macrophage polarization via β-catenin (CTNNB1) synergizes with cisplatin in lung cancer

Previous studies have demonstrated that tumor-associated macrophages (TAMs) exhibiting an M2 phenotype contribute significantly to the pathogenesis of various cancer types, including lung cancer. Therapeutic approaches targeting TAMs have the potential to complement and synergize with conventional chemotherapy and immunotherapy. Through database analysis, it has become evident that the expression of CTNNB1 (β-catenin) is predominantly localized in macrophages, and its presence is associated with unfavorable outcomes in the absence of CD8+ cells. Jin-Fu-An decoction (JFAD) has been utilized as an adjunct to augment current clinical interventions. By conducting a network pharmacological analysis, we discovered that CTNNB1 is a significant target of JFAD. Experiments were conducted to examine the impact of JFAD on macrophage polarization both in vitro and in vivo. Furthermore, the study investigated the combined effect of JFAD and cisplatin (CDDP) on mitigating adverse reactions and prolonging survival in subcutaneously transplanted tumor models and orthotopic lung cancer models. The percentage of M1 and M2 macrophages in the tumor and spleen were measured using flow cytometry. Additionally, the levels of β-catenin, M1, and M2 macrophage markers were measured by Western blotting and qPCR, while CD8 and iNOS protein expression was analyzed via immunohistochemistry. Our research findings indicate that JFAD has the ability to modulate the transformation of M2 macrophages into M1 macrophages, augment the anticancer efficacy of CDDP, and diminish the expression of cell-related markers in M2 cells. This regulatory effect may potentially be associated with the downregulation of β-catenin expression.

Accounting for intensity variation in image analysis of large-scale multiplexed clinical trial datasets

Multiplex immunofluorescence (mIF) imaging can provide comprehensive quantitative and spatial information for multiple immune markers for tumour immunoprofiling. However, application at scale to clinical trial samples sourced from multiple institutions is challenging due to pre-analytical heterogeneity. This study reports an analytical approach to the largest multi-parameter immunoprofiling study of clinical trial samples to date. We analysed 12,592 tissue microarray (TMA) spots from 3,545 colorectal cancers sourced from more than 240 institutions in two clinical trials (QUASAR 2 and SCOT) stained for CD4, CD8, CD20, CD68, FoxP3, pan-cytokeratin, and DAPI by mIF. TMA slides were multi-spectrally imaged and analysed by cell-based and pixel-based marker analysis. We developed an adaptive thresholding method to account for inter- and intra-slide intensity variation in TMA analysis. Applying this method effectively ameliorated inter- and intra-slide intensity variation improving the image analysis results compared with methods using a single global threshold. Correlation of CD8 data derived by our mIF analysis approach with single-plex chromogenic immunohistochemistry CD8 data derived from subsequent sections indicates the validity of our method (Spearman's rank correlation coefficients ρ between 0.63 and 0.66, p ≪ 0.01) as compared with the current gold standard analysis approach. Evaluation of correlation between cell-based and pixel-based analysis results confirms equivalency (ρ > 0.8, p ≪ 0.01, except for CD20 in the epithelial region) of both analytical approaches. These data suggest that our adaptive thresholding approach can enable analysis of mIF-stained clinical trial TMA datasets by digital pathology at scale for precision immunoprofiling.

scFv biofunctionalized nanoparticles to effective and safe targeting of CEA-expressing colorectal cancer cells

Colorectal cancer (CRC) is one of the deadliest cancers worldwide, with the 5 year survival rate in metastatic cases limited to 12%. The design of targeted and effective therapeutics remains a major unmet clinical need in CRC treatment. Carcinoembryonic antigen (CEA), a glycoprotein overexpressed in most colorectal tumors, may constitute a promising molecule for generating novel CEA-targeted therapeutic strategies for CRC treatment. Here, we developed a smart nanoplatform based on chemical conjugation of an anti-CEA single-chain variable fragment (scFv), MFE-23, with PLGA-PEG polymers to deliver the standard 5-Fluorouracil (5-FU) chemotherapy to CRC cells. We confirmed the specificity of the developed CEA-targeted NPs on the internalization by CEA-expressing CRC cells, with an enhance of threefold in the cell uptake. Additionally, CEA-targeted NPs loaded with 5-FU induced higher cytotoxicity in CEA-expressing cells, after 24 h and 48 h of treatment, reinforcing the specificity of the targeted NPs. Lastly, the safety of CEA-targeted NPs loaded with 5-FU was evaluated in donor-isolated macrophages, with no relevant impact on their metabolic activity nor polarization. Altogether, this proof of concept supports the CEA-mediated internalization of targeted NPs as a promising chemotherapeutic strategy for further investigation in different CEA-associated cancers and respective metastatic sites.Authors: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: [Maria José] Last name [Silveira]. Author 7 Given name: [Maria José] Last name [Oliveira]. Also, kindly confirm the details in the metadata are correctokAffiliations: Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.ok.

Tumor-associated macrophages: Potential therapeutic targets and diagnostic markers in cancer

Macrophages are plastic and functionally diverse, present in all tissues, and play a key role in organisms from development, homeostasis and repair, to immune responses to pathogens. They are central to many disease states and have emerged as important therapeutic targets for many diseases. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and are key factors influencing cancer progression, metastasis and tumor recurrence. TAMs can be derived from different sources and exert different pro- or anti-tumor effects based on the type, stage and immune composition of the tumor. TAMs are highly heterogeneous and diverse, and have multiple functional phenotypes. There is still a great deal of controversy regarding the relationship between TAMs and prognosis of cancer patients. In this review, we summarize the characteristics of common markers of TAMs as well as explore the prognostic role of TAMs in different cancers including lung, breast, gastric, colorectal, esophageal and ovarian cancers.

Immune regulation in gastric adenocarcinoma is linked with therapeutic efficacy and improved recovery

Adenocarcinomas are one of the most common histological types of gastric cancer. It has been ranked fifth among common cancers and is the third among death causing cancers worldwide. The high mortality rate among patients with gastric cancer is because of its silent evolution, genetic heterogeneity, high resistance to chemotherapy as well as unavailability of highly effective therapeutic strategy. Until now a number of several treatment strategies have been developed and are being practiced such as surgery, chemotherapy, radio therapy, and immunotherapy, however, further developments are required to improve the treatment responses and reduce the side effects. Therefore, novel personal therapeutic strategies based on immunological responses should be developed by targeting different check points and key immune players. Targeting macrophages and related molecular elements can be useful to achieve these goals. In this minireview, we discuss the available treatment options, molecular underpinnings and immunological regulations associated with gastric adenocarcinoma. We further describe the possible check points and immunological targets that can be used to develop novel therapeutic options.

Microsatellite Instability and Immune Response: From Microenvironment Features to Therapeutic Actionability-Lessons from Colorectal Cancer

Microsatellite instability (MSI) can be found in 15-20% of all colorectal cancers (CRC) and is the key feature of a defective DNA mismatch repair (MMR) system. Currently, MSI has been established as a unique and pivotal biomarker in the diagnosis, prognosis, and treatment of CRC. MSI tumors display a strong lymphocytic activation and a shift toward a tumoral microenvironment restraining metastatic potential and ensuing in a high responsiveness to immunotherapy of MSI CRC. Indeed, neoplastic cells with an MMR defect overexpress several immune checkpoint proteins, such as programmed death-1 (PD-1) and programmed death-ligand 1(PD-L1), that can be pharmacologically targeted, allowing for the revival the cytotoxic immune response toward the tumor. This review aims to illustrate the role of MSI in the tumor biology of colorectal cancer, focusing on the immune interactions with the microenvironment and their therapeutic implications.

Macrophages in immunoregulation and therapeutics

Macrophages exist in various tissues, several body cavities, and around mucosal surfaces and are a vital part of the innate immune system for host defense against many pathogens and cancers. Macrophages possess binary M1/M2 macrophage polarization settings, which perform a central role in an array of immune tasks via intrinsic signal cascades and, therefore, must be precisely regulated. Many crucial questions about macrophage signaling and immune modulation are yet to be uncovered. In addition, the clinical importance of tumor-associated macrophages is becoming more widely recognized as significant progress has been made in understanding their biology. Moreover, they are an integral part of the tumor microenvironment, playing a part in the regulation of a wide variety of processes including angiogenesis, extracellular matrix transformation, cancer cell proliferation, metastasis, immunosuppression, and resistance to chemotherapeutic and checkpoint blockade immunotherapies. Herein, we discuss immune regulation in macrophage polarization and signaling, mechanical stresses and modulation, metabolic signaling pathways, mitochondrial and transcriptional, and epigenetic regulation. Furthermore, we have broadly extended the understanding of macrophages in extracellular traps and the essential roles of autophagy and aging in regulating macrophage functions. Moreover, we discussed recent advances in macrophages-mediated immune regulation of autoimmune diseases and tumorigenesis. Lastly, we discussed targeted macrophage therapy to portray prospective targets for therapeutic strategies in health and diseases.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Macrophage morphology and distribution are strong predictors of prognosis in resected colorectal liver metastases: results from an external retrospective observational study

INTRODUCTION

Tumor-associated macrophages (TAMs) are key components of a tumoral microenvironment and have been shown to impact prognosis in different cancers. Previously reported data showed that TAM morphology correlates with prognosis in colorectal liver metastases (CLMs) after hepatectomy, with smaller TAMs (S-TAMs) conferring a more favorable prognosis than larger ones (L-TAMs). This study aims to externally validate this finding.

MATERIAL AND METHODS

The external cohort consisted of 84 formalin-fixed and paraffin-embedded surgical samples of CLMs and peritumoral tissue. Two-micrometer-section slides were obtained; the area and perimeter of 21 macrophages in each slide were recorded. The endpoints were TAMs morphometrics and their prognostic significance in relation to disease-free survival (DFS).

RESULTS

The average macrophage perimeter was 71.5±14.1 μm whilst the average area was 217.7±67.8 μm 2 . At univariate analysis, the TAM area demonstrated a statistically significant association with DFS ( P =0.0006). Optimal area cutoff value was obtained, showing a sensitivity and specificity of 92 and 56%, respectively. S-TAMs and L-TAMs were associated with 3-year DFS rates of 60 and 8.5%, respectively ( P <0.001). Multivariate analysis confirmed the predictive role of TAM area for DFS [hazard ratio (HR)=5.03; 95% CI=1.70-14.94; P =0.003]. Moreover, in a subset of patients ( n =12) characterized by unfavorable ( n =6, recurrence within 3 months) or favorable ( n =6, no recurrence after 48 months) prognosis, TAMs showed a different distribution: L-TAMs were more abundant and closer to the tumor invasive margin in patients that encountered early recurrence and tended to cluster in foci significantly larger ( P =0.02).

CONCLUSIONS

This external validation confirms that morphometric characterization of TAMs can serve as a simple readout of their diversity and allows to reliably stratify patient outcomes and predict disease recurrence after hepatectomy for CLMs.

In silico analysis to identify miR-1271-5p/PLCB4 (phospholipase C Beta 4) axis mediated oxaliplatin resistance in metastatic colorectal cancer

Oxaliplatin (OXA) is the first-line chemotherapy drug for metastatic colorectal cancer (mCRC), and the emergence of drug resistance is a major clinical challenge. Although there have been numerous studies on OXA resistance, but its underlying molecular mechanisms are still unclear. This study aims to identify key regulatory genes and pathways associated with OXA resistance. The Gene Expression Omnibus (GEO) GSE42387 dataset containing gene expression profiles of parental and OXA-resistant LoVo cells was applied to explore potential targets. GEO2R, STRING, CytoNCA (a plug-in of Cytoscape), and DAVID were used to analyze differentially expressed genes (DEGs), protein-protein interactions (PPIs), hub genes in PPIs, and gene ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. R2 online platform was used to run a survival analysis of validated hub genes enriched in KEGG pathways. The ENCORI database predicted microRNAs for candidate genes. A survival analysis of those genes was performed, and validated using the OncoLnc database. In addition, the 'clusterProfiler' package in R was used to perform gene set enrichment analysis (GSEA). We identified 395 DEGs, among which 155 were upregulated and 240 were downregulated. In total, 95 DEGs were screened as hub genes after constructing the PPI networks. Twelve GO terms and three KEGG pathways (steroid hormone biosynthesis, malaria, and pathways in cancer) were identified as being significant in the enrichment analysis of hub genes. Twenty-one hub genes enriched in KEGG pathways were defined as key genes. Among them AKT3, phospholipase C Beta 4 (PLCB4), and TGFB1 were identified as OXA-resistance genes through the survival analysis. High expressions of AKT3 and TGFB1 were each associated with a poor prognosis, and lower expression of PLCB4 was correlated with worse survival. Further, high levels of hsa-miR-1271-5p, which potentially targets PLCB4, were associated with poor overall survival in patients with CRC. Finally, we found that PLCB4 low expression was associated with MAPK signaling pathway and VEGF signaling pathway in CRC. Our results demonstrated that hsa-miR-1271-5p/PLCB4 in the pathway in cancer could be a new potential therapeutic target for mCRC with OXA resistance.

Relationship between Epithelial-to-Mesenchymal Transition and Tumor-Associated Macrophages in Colorectal Liver Metastases

The liver is the most common metastatic site in colorectal cancer (CRC) patients. Indeed, 25-30% of the cases develop colorectal liver metastasis (CLM), showing an extremely poor 5-year survival rate and resistance to conventional anticancer therapies. Tumor-associated macrophages (TAMs) provide a nurturing microenvironment for CRC metastasis, promoting epithelial-to-mesenchymal transition (EMT) through the TGF-β signaling pathway, thus driving tumor cells to acquire mesenchymal properties that allow them to migrate from the primary tumor and invade the new metastatic site. EMT is known to contribute to the disruption of blood vessel integrity and the generation of circulating tumor cells (CTCs), thus being closely related to high metastatic potential in numerous solid cancers. Despite the fact that it is well-recognized that the crosstalk between tumor cells and the inflammatory microenvironment is crucial in the EMT process, the association between the EMT and the role of TAMs is still poorly understood. In this review, we elaborated on the role that TAMs exert in the induction of EMT during CLM development. Since TAMs are the major source of TGF-β in the liver, we also focused on novel insights into their role in TGF-β-induced EMT.

Proteomic characterization of gastric cancer response to chemotherapy and targeted therapy reveals new therapeutic strategies

Chemotherapy and targeted therapy are the major treatments for gastric cancer (GC), but drug resistance limits its effectiveness. Here, we profile the proteome of 206 tumor tissues from patients with GC undergoing either chemotherapy or anti-HER2-based therapy. Proteome-based classification reveals four subtypes (G-I-G-IV) related to different clinical and molecular features. MSI-sig high GC patients benefit from docetaxel combination treatment, accompanied by anticancer immune response. Further study reveals patients with high T cell receptor signaling respond to anti-HER2-based therapy; while activation of extracellular matrix/PI3K-AKT pathway impair anti-tumor effect of trastuzumab. We observe CTSE functions as a cell intrinsic enhancer of chemosensitivity of docetaxel, whereas TKTL1 functions as an attenuator. Finally, we develop prognostic models with high accuracy to predict therapeutic response, further validated in an independent validation cohort. This study provides a rich resource for investigating the mechanisms and indicators of chemotherapy and targeted therapy in GC.

Macrophages as tools and targets in cancer therapy

Tumour-associated macrophages are an essential component of the tumour microenvironment and have a role in the orchestration of angiogenesis, extracellular matrix remodelling, cancer cell proliferation, metastasis and immunosuppression, as well as in resistance to chemotherapeutic agents and checkpoint blockade immunotherapy. Conversely, when appropriately activated, macrophages can mediate phagocytosis of cancer cells and cytotoxic tumour killing, and engage in effective bidirectional interactions with components of the innate and adaptive immune system. Therefore, they have emerged as therapeutic targets in cancer therapy. Macrophage-targeting strategies include inhibitors of cytokines and chemokines involved in the recruitment and polarization of tumour-promoting myeloid cells as well as activators of their antitumorigenic and immunostimulating functions. Early clinical trials suggest that targeting negative regulators (checkpoints) of myeloid cell function indeed has antitumor potential. Finally, given the continuous recruitment of myelomonocytic cells into tumour tissues, macrophages are candidates for cell therapy with the development of chimeric antigen receptor effector cells. Macrophage-centred therapeutic strategies have the potential to complement, and synergize with, currently available tools in the oncology armamentarium.

Macrophages can promote tumorigenesis and enhance the antitumour response. This Review discusses the molecular mechanisms underlying the reprogramming of macrophages in the tumour microenvironment and provides an overview of macrophage-targeted therapies for the treatment of cancer.

Cytokine- and chemokine-induced inflammatory colorectal tumor microenvironment: Emerging avenue for targeted therapy

Colorectal cancer (CRC) is a predominant life-threatening cancer, with liver and peritoneal metastases as the primary causes of death. Intestinal inflammation, a known CRC risk factor, nurtures a local inflammatory environment enriched with tumor cells, endothelial cells, immune cells, cancer-associated fibroblasts, immunosuppressive cells, and secretory growth factors. The complex interactions of aberrantly expressed cytokines, chemokines, growth factors, and matrix-remodeling enzymes promote CRC pathogenesis and evoke systemic responses that affect disease outcomes. Mounting evidence suggests that these cytokines and chemokines play a role in the progression of CRC through immunosuppression and modulation of the tumor microenvironment, which is partly achieved by the recruitment of immunosuppressive cells. These cells impart features such as cancer stem cell-like properties, drug resistance, invasion, and formation of the premetastatic niche in distant organs, promoting metastasis and aggressive CRC growth. A deeper understanding of the cytokine- and chemokine-mediated signaling networks that link tumor progression and metastasis will provide insights into the mechanistic details of disease aggressiveness and facilitate the development of novel therapeutics for CRC. Here, we summarized the current knowledge of cytokine- and chemokine-mediated crosstalk in the inflammatory tumor microenvironment, which drives immunosuppression, resistance to therapeutics, and metastasis during CRC progression. We also outlined the potential of this crosstalk as a novel therapeutic target for CRC. The major cytokine/chemokine pathways involved in cancer immunotherapy are also discussed in this review.

Tumor-associated macrophages and risk of recurrence in stage III colorectal cancer

Tumor‐associated macrophages (TAMs) have a unique favorable effect on the prognosis of colorectal cancer (CRC), although their association with stage‐specific outcomes remains unclear. We assessed the densities of CD68⁺ and CD163⁺ TAMs at the invasive front of resected CRC stage III CRC from 236 patients, 165 of whom received post‐surgical FOLFOX treatment, and their relationship with disease‐free survival (DFS). Associations between macrophage mRNAs and clinical outcome were investigated in silico in 59 stage III CRC and FOLFOX‐treated patients from The Cancer Genome Atlas (TCGA). Biological interactions of SW480 and HT29 cells and macrophages with FOLFOX were tested in co‐culture models. Low TAM densities were associated with shorter DFS among patients receiving FOLFOX (CD68⁺, p = 0.0001; CD163⁺, p = 0.0008) but not among those who were untreated. By multivariate Cox analysis, only low TAM (CD68⁺, p = 0.001; CD163⁺, p = 0.002) and nodal status (CD68⁺, p = 0.009; CD163⁺, p = 0.007) maintained an independent predictive value. In the TCGA cohort, high CD68 mRNA levels were associated with better outcome (p = 0.02). Macrophages enhanced FOLFOX cytotoxicity on CRC cells (p < 0.01), and drugs oriented macrophage polarization from M2‐ to M1‐phenotype. Low TAM densities identify stage III CRC patients at higher risk of recurrence after adjuvant therapy, and macrophages can augment the chemo‐sensitivity of micro‐metastases.

Drug Resistance in Colorectal Cancer: From Mechanism to Clinic

Colorectal cancer (CRC) is one of the leading causes of death worldwide. The 5-year survival rate is 90% for patients with early CRC, 70% for patients with locally advanced CRC, and 15% for patients with metastatic CRC (mCRC). In fact, most CRC patients are at an advanced stage at the time of diagnosis. Although chemotherapy, molecularly targeted therapy and immunotherapy have significantly improved patient survival, some patients are initially insensitive to these drugs or initially sensitive but quickly become insensitive, and the emergence of such primary and secondary drug resistance is a significant clinical challenge. The most direct cause of resistance is the aberrant anti-tumor drug metabolism, transportation or target. With more in-depth research, it is found that cell death pathways, carcinogenic signals, compensation feedback loop signal pathways and tumor immune microenvironment also play essential roles in the drug resistance mechanism. Here, we assess the current major mechanisms of CRC resistance and describe potential therapeutic interventions.

Targeting the Tumor Microenvironment: A Close Up of Tumor-Associated Macrophages and Neutrophils

The importance of the tumor microenvironment (TME) in dynamically regulating cancer progression and influencing the therapeutic outcome is widely accepted and appreciated. Several therapeutic strategies to modify or modulate the TME, like angiogenesis or immune checkpoint inhibitors, showed clinical efficacy and received approval from regulatory authorities. Within recent decades, new promising strategies targeting myeloid cells have been implemented in preclinical cancer models. The predominance of specific cell phenotypes in the TME has been attributed to pro- or anti-tumoral. Hence, their modulation can, in turn, alter the responses to standard-of-care treatments, making them more or less effective. Here, we summarize and discuss the current knowledge and the correlated challenges about the tumor-associated macrophages and neutrophils targeting strategies, current treatments, and future developments.

Functional and Therapeutic Significance of Tumor-Associated Macrophages in Colorectal Cancer

The role of the tumor microenvironment (TME) in the progression of colorectal cancer (CRC) and its acquisition of resistance to treatment become the research hotspots. As an important component of TME, the tumor-associated macrophages (TAMs) regulate multiple critical oncogenic processes, namely, occurrence, proliferation, metastasis, and drug resistance in CRC. In this review, we have discussed the functional and therapeutic significance of TAMs in CRC. M1 macrophages act as the tumor suppressor while M2 macrophages promote CRC. The polarization of TAMs is mainly regulated by the pathways such as NFKB1 pathways, STAT3 pathways, WNT5A pathways, and PI3K pathways in CRC. Furthermore, the M2 polarization of TAMs is not only controllable but also reversible. Finally, we provide insights into the TAMs-targeted therapeutic strategies.

Macrophages play a role in inflammatory transformation of colorectal cancer

Colorectal cancer (CRC) is one of the most common and fatal cancers worldwide, and it is also a typical inflammatory cancer. The function of macrophages is very important in the tissue immune microenvironment during inflammatory and carcinogenic transformation. Here, we evaluated the function and mechanism of macrophages in intestinal physiology and in different pathological stages. Furthermore, the role of macrophages in the immune microenvironment of CRC and the influence of the intestinal population and hypoxic environment on macrophage function are summarized. In addition, in the era of tumor immunotherapy, CRC currently has a limited response rate to immune checkpoint inhibitors, and we summarize potential therapeutic strategies for targeting tumor-associated macrophages.

PD-L1 expression and immune cells infiltration in primary tracheobronchial neoplasm

BACKGROUND

Primary tracheobronchial neoplasm is rare yet poses a serious threat to life. Due to its low incidence, the immune microenvironment of such tumors remained unclear. This study aimed to clarify the expression of programmed death-ligand 1 (PD-L1) and infiltration of immune cells in primary tracheobronchial neoplasm, which might be useful for guiding treatment and evaluating clinical outcome.

METHODS

We assessed retrospectively the expression of PD-L1 and infiltration in cells expressing CD8, CD16, CD68, CD163 and FOXP3 in 21 patients with primary tracheobronchial neoplasm who underwent surgery in Tangdu Hospital from January 2016 to July 2021. The expression of PD-L1 was assessed based on the tumor proportion score system. The density of immune cells was analyzed by automatic image analysis software.

RESULTS

In this study, all of 16 participants with adenoid cystic carcinoma (ACC) had no expression of PD-L1, whereas 4/5 (80%) of those with squamous cell carcinomas (SCC) were positive for PD-L1 expression. Compared with ACC, the density of FOXP3+ cells in both the intratumoral region and peritumoral region was higher in SCC (P<0.01). The density of FOXP3+ cells was significantly higher than that of CD8+, CD16+, and CD163+ cells in SCC in the intratumoral region (P<0.01). In contrast, the density of FOXP3+ cells was significantly lower than that of CD8+, CD16+, and CD68+ cells in ACC in both the intratumoral region and peritumoral regions. The density of CD68+ cells was significantly higher than that of CD8+ cells (P<0.05) and CD163+ cells (P<0.01) in ACC in the intratumoral region. Furthermore, the tumors of patients with metastasis more commonly of immune-excluded status, in which the CD8+ cells accumulated in peritumoral region.

CONCLUSIONS

This study demonstrated that the expression of PD-L1 in primary tracheobronchial neoplasm was mainly concentrated in patients with SCC. In the immune microenvironment of SCC, FOXP3+ cells were the dominant immune cells, while in the immune microenvironment of ACC, CD68+ cells were the main immune cells. Therefore, the immune microenvironment was significantly different in primary tracheobronchial neoplasm according to histology.

Tumor microenvironment in triple-negative breast cancer: the correlation of tumor-associated macrophages and tumor-infiltrating lymphocytes

PURPOSE

Immune cells such as cytotoxic T cells, helper T cells, B cells or tumor-associated macrophages (TAMs) contribute to the anti-tumor response or pro-tumorigenic effect in triple negative breast cancer (TNBC). The interrelation of TAMs, T and B tumor-infiltrating lymphocytes (TILs) in TNBC has not been fully elucidated.

METHODS

We evaluated the association of tumor-associated macrophages, T and B TILs in TNBC.

RESULTS

TNBCs with a high CD68+, CD163+ TAMs and low CD4+, CD8+, CD20+ TILs had a significantly shorter relapse-free survival (RFS) and overall survival (OS) than those with low CD68+, CD163+ TAMs and high CD4+, CD8+, CD20+ TILs. TNBCs with high CD68+ TAMs/low CD8+ TILs showed a significantly shorter RFS and OS and a significantly poorer prognosis than those with high CD68+ TAMs/high CD8+ TILs, low CD68+ TAMs/high CD8+ TILs, and low CD68+/low CD8+. TNBCs with high CD163+ TAMs/low CD8+, low CD20 + TILs showed a significantly shorter RFS and OS and a significantly poorer prognosis than those with high CD163+ TAMs/high CD8+ TILs and high CD163+ TAMs /high CD20+ TILs.

CONCLUSIONS

Our study suggests that TAMs further create an optimal tumor microenvironment (TME) for growth and invasion of cancer cells when evasion of immunoreactions due to T and B TILs occurs. In TNBCs, all these events combine to affect prognosis. The process of TME is highly complex in TNBCs and for an improved understanding, larger validation studies are necessary to confirm these findings.

Epithelial to Mesenchymal Transition: A Challenging Playground for Translational Research. Current Models and Focus on TWIST1 Relevance and Gastrointestinal Cancers

Resembling the development of cancer by multistep carcinogenesis, the evolution towards metastasis involves several passages, from local invasion and intravasation, encompassing surviving anoikis into the circulation, landing at distant sites and therein establishing colonization, possibly followed by the outgrowth of macroscopic lesions. Within this cascade, epithelial to mesenchymal transition (EMT) works as a pleiotropic program enabling cancer cells to overcome local, systemic, and distant barriers against diffusion by replacing traits and functions of the epithelial signature with mesenchymal-like ones. Along the transition, a full-blown mesenchymal phenotype may not be accomplished. Rather, the plasticity of the program and its dependency on heterotopic signals implies a pendulum with oscillations towards its reversal, that is mesenchymal to epithelial transition. Cells in intermixed E⇔M states can also display stemness, enabling their replication together with the epithelial reversion next to successful distant colonization. If we aim to include the EMT among the hallmarks of cancer that could modify clinical practice, the gap between the results pursued in basic research by animal models and those achieved in translational research by surrogate biomarkers needs to be filled. We review the knowledge on EMT, derived from models and mechanistic studies as well as from translational studies, with an emphasis on gastrointestinal cancers (GI).

Omental Macrophagic "Crown-like Structures" Are Associated with Poor Prognosis in Advanced-Stage Serous Ovarian Cancer

The tumor microenvironment is a well-recognized framework in which immune cells present in the tumor microenvironment promote or inhibit cancer formation and development. A crown-like structure (CLS) has been reported as a dying or dead adipocyte surrounded by a 'crown' of macrophages within adipose tissue, which is a histologic hallmark of the inflammatory process in this tissue. CLSs have also been found to be related to formation, progression and prognosis of some types of cancer. However, the presence of CLSs in the omentum of advanced-stage high-grade serous ovarian carcinoma (HGSOC) has not been thoroughly investigated. By using CD68, a pan-macrophage marker, and CD163, an M2-like polarization macrophage marker, immunohistochemistry (IHC) was performed to identify tumor-associated macrophages (TAMs) and CLSs. This retrospective study analyzed 116 patients with advanced-stage HGSOC who received complete treatment and had available clinical data from July 2008 through December 2016 at National Cheng Kung University Hospital (NCKUH) (Tainan, Taiwan). Based on multivariate Cox regression analysis, patients with omental CD68⁺ CLSs had poor OS (median survival: 24 vs. 38 months, p = 0.001, hazard ratio (HR): 2.26, 95% confidence interval (CI): 1.41-3.61); patients with omental CD163⁺ CLSs also had poor OS (median survival: 22 vs. 36 months, HR: 2.14, 95%CI: 1.33-3.44, p = 0.002). Additionally, patients with omental CD68⁺ or CD163⁺ CLSs showed poor PFS (median survival: 11 vs. 15 months, HR: 2.28, 95%CI: 1.43-3.64, p = 0.001; median survival: 11 vs. 15 months, HR: 2.17, 95%CI: 1.35-3.47, respectively, p = 0.001). Conversely, the density of CD68⁺ or CD163⁺ TAMs in ovarian tumors was not associated with patient prognosis in advanced-stage HGSOC in our cohort. In conclusion, we, for the first time, demonstrate that the presence of omental CLSs is associated with poor prognosis in advanced-stage HGSOC.

Functionalized Nanoparticles Targeting Tumor-Associated Macrophages as Cancer Therapy

The tumor microenvironment (TME) plays a central role in regulating antitumor immune responses. As an important part of the TME, alternatively activated type 2 (M2) macrophages drive the development of primary and secondary tumors by promoting tumor cell proliferation, tumor angiogenesis, extracellular matrix remodeling and overall immunosuppression. Immunotherapy approaches targeting tumor-associated macrophages (TAMs) in order to reduce the immunosuppressive state in the TME have received great attention. Although these methods hold great potential for the treatment of several cancers, they also face some limitations, such as the fast degradation rate of drugs and drug-induced cytotoxicity of organs and tissues. Nanomedicine formulations that prevent TAM signaling and recruitment to the TME or deplete M2 TAMs to reduce tumor growth and metastasis represent encouraging novel strategies in cancer therapy. They allow the specific delivery of antitumor drugs to the tumor area, thereby reducing side effects associated with systemic application. In this review, we give an overview of TAM biology and the current state of nanomedicines that target M2 macrophages in the course of cancer immunotherapy, with a specific focus on nanoparticles (NPs). We summarize how different types of NPs target M2 TAMs, and how the physicochemical properties of NPs (size, shape, charge and targeting ligands) influence NP uptake by TAMs in vitro and in vivo in the TME. Furthermore, we provide a comparative analysis of passive and active NP-based TAM-targeting strategies and discuss their therapeutic potential.

Bringing Macrophages to the Frontline against Cancer: Current Immunotherapies Targeting Macrophages

Macrophages are found in all tissues and display outstanding functional diversity. From embryo to birth and throughout adult life, they play critical roles in development, homeostasis, tissue repair, immunity, and, importantly, in the control of cancer growth. In this review, we will briefly detail the multi-functional, protumoral, and antitumoral roles of macrophages in the tumor microenvironment. Our objective is to focus on the ever-growing therapeutic opportunities, with promising preclinical and clinical results developed in recent years, to modulate the contribution of macrophages in oncologic diseases. While the majority of cancer immunotherapies target T cells, we believe that macrophages have a promising therapeutic potential as tumoricidal effectors and in mobilizing their surroundings towards antitumor immunity to efficiently limit cancer progression.

Macrophage targeting in cancer

Tumorigenesis is not only determined by the intrinsic properties of cancer cells but also by their interactions with components of the tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are among the most abundant immune cells in the TME. During initial stages of tumor development, macrophages can either directly promote antitumor responses by killing tumor cells or indirectly recruit and activate other immune cells. As genetic changes occur within the tumor or T helper 2 (TH 2) cells begin to dominate the TME, TAMs begin to exhibit an immunosuppressive protumor phenotype that promotes tumor progression, metastasis, and resistance to therapy. Thus, targeting TAMs has emerged as a strategy for cancer therapy. To date, TAM targeting strategies have focused on macrophage depletion and inhibition of their recruitment into the TME. However, these strategies have shown limited therapeutic efficacy, although trials are still underway with combination therapies. The fact that macrophages have the potential for antitumor activity has moved the TAM targeting field toward the development of TAM-reprogramming strategies to support this antitumor immune response. Here, we discuss the various roles of TAMs in cancer therapy and their immunosuppressive properties, as well as implications for emerging checkpoint inhibitor-based immunotherapies. We review state-of-the-art TAM-targeting strategies, focusing on current ones at the preclinical and clinical trial stages that aim to reprogram TAMs as an oncological therapy.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

Tumor-Associated Macrophages: Combination of Therapies, the Approach to Improve Cancer Treatment

Macrophages are one of the most important cells of the innate immune system and are known for their ability to engulf and digest foreign substances, including cellular debris and tumor cells. They can convert into tumor-associated macrophages (TAMs) when mature macrophages are recruited into the tumor microenvironment. Their role in cancer progression, metastasis, and therapy failure is of special note. The aim of this review is to understand how the presence of TAMs are both advantageous and disadvantageous in the immune system.

Data Driven Mathematical Model of FOLFIRI Treatment for Colon Cancer

Many colon cancer patients show resistance to their treatments. Therefore, it is important to consider unique characteristic of each tumor to find the best treatment options for each patient. In this study, we develop a data driven mathematical model for interaction between the tumor microenvironment and FOLFIRI drug agents in colon cancer. Patients are divided into five distinct clusters based on their estimated immune cell fractions obtained from their primary tumors' gene expression data. We then analyze the effects of drugs on cancer cells and immune cells in each group, and we observe different responses to the FOLFIRI drugs between patients in different immune groups. For instance, patients in cluster 3 with the highest T-reg/T-helper ratio respond better to the FOLFIRI treatment, while patients in cluster 2 with the lowest T-reg/T-helper ratio resist the treatment. Moreover, we use ROC curve to validate the model using the tumor status of the patients at their follow up, and the model predicts well for the earlier follow up days.

Heterogeneity of Colorectal Cancer Progression: Molecular Gas and Brakes

The review begins with molecular genetics, which hit the field unveiling the involvement of oncogenes and tumor suppressor genes in the pathogenesis of colorectal cancer (CRC) and uncovering genetic predispositions. Then the notion of molecular phenotypes with different clinical behaviors was introduced and translated in the clinical arena, paving the way to next-generation sequencing that captured previously unrecognized heterogeneity. Among other molecular regulators of CRC progression, the extent of host immune response within the tumor micro-environment has a critical position. Translational sciences deeply investigated the field, accelerating the pace toward clinical transition, due to its strong association with outcomes. While the perturbation of gut homeostasis occurring in inflammatory bowel diseases can fuel carcinogenesis, micronutrients like vitamin D and calcium can act as brakes, and we discuss underlying molecular mechanisms. Among the components of gut microbiota, Fusobacterium nucleatum is over-represented in CRC, and may worsen patient outcome. However, any translational knowledge tracing the multifaceted evolution of CRC should be interpreted according to the prognostic and predictive frame of the TNM-staging system in a perspective of clinical actionability. Eventually, we examine challenges and promises of pharmacological interventions aimed to restrain disease progression at different disease stages.

Chemotherapy Induces Tumor-Associated Macrophages that Aid Adaptive Immune Responses in Ovarian Cancer

Neoadjuvant chemotherapy (NACT) may stimulate anticancer adaptive immune responses in high-grade serous ovarian cancer (HGSOC), but little is known about effects on innate immunity. Using omental biopsies from HGSOC, and omental tumors from orthotopic mouse HGSOC models that replicate the human tumor microenvironment, we studied the impact of platinum-based NACT on tumor-associated macrophages (TAM). We found that chemotherapy reduces markers associated with alternative macrophage activation while increasing expression of proinflammatory pathways, with evidence of inflammasome activation. Further evidence of a shift in TAM functions came from macrophage depletion via CSF1R inhibitors (CSF1Ri) in the mouse models. Although macrophage depletion in established disease had no impact on tumor weight or survival, CSF1Ri treatment after chemotherapy significantly decreased disease-free and overall survival. This decrease in survival was accompanied by significant inhibition of adaptive immune response pathways in the tumors. We conclude that chemotherapy skews the TAM population in HSGOC toward an antitumor phenotype that may aid adaptive immune responses, and therapies that enhance or sustain this during remission may delay relapse.

Tumour immune microenvironment biomarkers predicting cytotoxic chemotherapy efficacy in colorectal cancer

The role of the local tumour and stromal immune landscape is increasingly recognised to be important in cancer development, progression and response to therapy. The composition, function, spatial orientation and gene expression profile of the infiltrate of the innate and adaptive immune system at the tumour and surrounding tissue has an established prognostic role in colorectal cancer (CRC). Multiple studies have confirmed that a tumour immune microenvironment (TIME) reflective of a type 1 adaptive immune response is associated with improved prognosis. There have been significant efforts to evolve these observations into validated, histopathology-based prognostic biomarkers, such as the Immunoscore. However, the clinical need lies much more in the development of predictive, not prognostic, biomarkers which have the potential to improve patient outcomes. This is particularly pertinent to help guide cytotoxic chemotherapy use in CRC, which remains the standard of care. Cytotoxic chemotherapy has recognised immunomodulatory activity distinct from its antimitotic effects, including mechanisms such as immunogenic cell death (ICD) and induction/inhibition of key immune players. Response to chemotherapy may differ with regard to molecular subtype of CRC, which are strongly associated with immune phenotypes. Thus, immune markers are potentially useful, though under-reported, predictive biomarkers. In this review, we discuss the impact of the TIME on response to cytotoxic chemotherapy in CRC, with a focus on baseline immune markers, and associated genomic and transcriptomic signatures.

Macrophage morphology correlates with single-cell diversity and prognosis in colorectal liver metastasis

It has long been known that in vitro polarized macrophages differ in morphology. Stemming from a conventional immunohistology observation, we set out to test the hypothesis that morphology of tumor-associated macrophages (TAMs) in colorectal liver metastasis (CLM) represents a correlate of functional diversity with prognostic significance. Density and morphological metrics of TAMs were measured and correlated with clinicopathological variables. While density of TAMs did not correlate with survival of CLM patients, the cell area identified small (S-TAM) and large (L-TAM) macrophages that were associated with 5-yr disease-free survival rates of 27.8% and 0.2%, respectively (P < 0.0001). RNA sequencing of morphologically distinct macrophages identified LXR/RXR as the most enriched pathway in large macrophages, with up-regulation of genes involved in cholesterol metabolism, scavenger receptors, MERTK, and complement. In single-cell analysis of mononuclear phagocytes from CLM tissues, S-TAM and L-TAM signatures were differentially enriched in individual clusters. These results suggest that morphometric characterization can serve as a simple readout of TAM diversity with strong prognostic significance.

Tumor-associated myeloid cells: diversity and therapeutic targeting

Myeloid cells in tumor tissues constitute a dynamic immune population characterized by a non-uniform phenotype and diverse functional activities. Both tumor-associated macrophages (TAMs), which are more abundantly represented, and tumor-associated neutrophils (TANs) are known to sustain tumor cell growth and invasion, support neoangiogenesis and suppress anticancer adaptive immune responses. In recent decades, several therapeutic approaches have been implemented in preclinical cancer models to neutralize the tumor-promoting roles of both TAMs and TANs. Some of the most successful strategies have now reached the clinic and are being investigated in clinical trials. In this review, we provide an overview of the recent literature on the ever-growing complexity of the biology of TAMs and TANs and the development of the most promising approaches to target these populations therapeutically in cancer patients.

Therapeutic Manipulation of Tumor-associated Macrophages: Facts and Hopes from a Clinical and Translational Perspective

The stroma of most solid tumors is populated by myeloid cells, which mostly represent macrophages. Tumor-associated macrophages (TAMs), strongly influenced by cancer cell-derived factors, are key drivers of immunosuppression and support tumor growth and spread to distant sites. Their accurate quantification and characterization in the tumor microenvironment are gaining prognostic value: increasing evidence demonstrates their ability to hamper cancer patients' response to chemotherapy, as well as to immunotherapies based on checkpoint inhibition. Therefore, strategies to counteract their negative effects are nowadays gaining momentum at preclinical, translational, and clinical levels. Our knowledge of the biology of TAMs has greatly advanced in the last years; several strategies to target and reprogram their functions to become antitumor effectors have proven successful in experimental preclinical tumor models; on the other hand, few approaches have so far been effectively translated into clinic practice. A growing interest in the therapeutic manipulation of TAMs is evidenced by numerous early-phase clinical trials, which are continuously fueled by new discoveries from basic research. This gives us hope that the targeting and sustained reprogramming of TAMs will be more specific to synergize with current therapies and maximize antitumor responses in patients.

Immunization with alloantibodies-covered melanoma cells induces regional antitumor effects that become systemic when combined with 5-FU treatment

Alloantibodies, in particular immunoglobulin G (allo-IgG), confer a rejection advantage to tumors sharing the same major histocompatibility complex (MHC) in mice. However, when administrated intratumorally, this effect can only be achieved in combination with dendritic cells (DCs) activation. Here, we developed high titer allo-IgG by multiple rounds of immunization with allogenic B16 melanoma cells, which allows for the strong binding with B16 cells. We demonstrate that B16 cells incubated with these allo-IgG (referred to as allo-IgG-B16) become highly immunogenic, which release tumor antigens that are efficiently presented by classic DCs in lymph nodes (LNs). Injection of allo-IgG-B16 turns the tumor into an immune hot one and even elicits a systemic antitumor response when used together with 5-fluorouracil (5-FU). This systemic response is tumor-specific and relies on the critical site - LNs. Our findings provide a rationale for the use of allo-IgG in cancer treatment.

Evolution of Experimental Models in the Study of Glioblastoma: Toward Finding Efficient Treatments

Glioblastoma (GBM) is the most common form of brain tumor characterized by its resistance to conventional therapies, including temozolomide, the most widely used chemotherapeutic agent in the treatment of GBM. Within the tumor, the presence of glioma stem cells (GSC) seems to be the reason for drug resistance. The discovery of GSC has boosted the search for new experimental models to study GBM, which allow the development of new GBM treatments targeting these cells. In here, we describe different strategies currently in use to study GBM. Initial GBM investigations were focused in the development of xenograft assays. Thereafter, techniques advanced to dissociate tumor cells into single-cell suspensions, which generate aggregates referred to as neurospheres, thus facilitating their selective expansion. Concomitantly, the finding of genes involved in the initiation and progression of GBM tumors, led to the generation of mice models for the GBM. The latest advances have been the use of GBM organoids or 3D-bioprinted mini-brains. 3D bio-printing mimics tissue cytoarchitecture by combining different types of cells interacting with each other and with extracellular matrix components. These in vivo models faithfully replicate human diseases in which the effect of new drugs can easily be tested. Based on recent data from human glioblastoma, this review critically evaluates the different experimental models used in the study of GB, including cell cultures, mouse models, brain organoids, and 3D bioprinting focusing in the advantages and disadvantages of each approach to understand the mechanisms involved in the progression and treatment response of this devastating disease.

Tumor-associated macrophages: potential therapeutic strategies and future prospects in cancer

Macrophages are the most important phagocytes in vivo. However, the tumor microenvironment can affect the function and polarization of macrophages and form tumor-associated macrophages (TAMs). Usually, the abundance of TAMs in tumors is closely associated with poor prognosis. Preclinical studies have identified important pathways regulating the infiltration and polarization of TAMs during tumor progression. Furthermore, potential therapeutic strategies targeting TAMs in tumors have been studied, including inhibition of macrophage recruitment to tumors, functional repolarization of TAMs toward an antitumor phenotype, and other therapeutic strategies that elicit macrophage-mediated extracellular phagocytosis and intracellular destruction of cancer cells. Therefore, with the increasing impact of tumor immunotherapy, new antitumor strategies to target TAMs are now being discussed.

The Prognostic Role of Macrophage Polarization in the Colorectal Cancer Microenvironment

Macrophages are among the most common cells in the colorectal cancer microenvironment, but their prognostic significance is incompletely understood. Using multiplexed immunofluorescence for CD68, CD86, IRF5, MAF, MRC1 (CD206), and KRT (cytokeratins) combined with digital image analysis and machine learning, we assessed the polarization spectrum of tumor-associated macrophages in 931 colorectal carcinomas. We then applied Cox proportional hazards regression to assess prognostic survival associations of intraepithelial and stromal densities of M1-like and M2-like macrophages while controlling for potential confounders, including stage and microsatellite instability status. We found that high tumor stromal density of M2-like macrophages was associated with worse cancer-specific survival, whereas tumor stromal density of M1-like macrophages was not significantly associated with better cancer-specific survival. High M1:M2 density ratio in tumor stroma was associated with better cancer-specific survival. Overall macrophage densities in tumor intraepithelial or stromal regions were not prognostic. These findings suggested that macrophage polarization state, rather than their overall density, was associated with cancer-specific survival, with M1- and M2-like macrophage phenotypes exhibiting distinct prognostic roles. These results highlight the utility of a multimarker strategy to assess the macrophage polarization at single-cell resolution within the tumor microenvironment.

Macrophage imaging and subset analysis using single-cell RNA sequencing

Macrophages have been associated with drug response and resistance in diverse settings, thus raising the possibility of using macrophage imaging as a companion diagnostic to inform personalized patient treatment strategies. Nanoparticle-based contrast agents are especially promising because they efficiently deliver fluorescent, magnetic, and/or radionuclide labels by leveraging the intrinsic capacity of macrophages to accumulate nanomaterials in their role as professional phagocytes. Unfortunately, current clinical imaging modalities are limited in their ability to quantify broad molecular programs that may explain (a) which particular cell subsets a given imaging agent is actually labeling, and (b) what mechanistic role those cells play in promoting drug response or resistance. Highly multiplexed single-cell approaches including single-cell RNA sequencing (scRNAseq) have emerged as resources to help answer these questions. In this review, we query recently published scRNAseq datasets to support companion macrophage imaging, with particular focus on using dextran-based nanoparticles to predict the action of anti-cancer nanotherapies and monoclonal antibodies.

Prognostic and Predictive Cross-Roads of Microsatellite Instability and Immune Response to Colon Cancer

Understanding molecular features of colon cancer has shed light on its pathogenesis and progression. Over time, some of these features acquired clinical dignity and were incorporated in decision making. Namely, microsatellite instability (MSI) due to mismatch repair of defects, which primarily was adopted for the diagnosis of Lynch syndrome, became recognized as the biomarker of a different disease type, showing a less aggressive behavior. MSI tumors harbor high amounts of tumor infiltrating lymphocytes (TILs) due to their peculiar load in neoantigens. However, microsatellite stable colon cancer may also show high amounts of TILs, and this feature is as well associated with better outcomes. High TIL loads are in general associated with a favorable prognosis, especially in stage II colon cancer, and therein identifies a patient subset with the lowest probability of relapse. With respect to post-surgical adjuvant treatment, particularly in stage III, TILs predictive ability seems to weaken along with the progression of the disease, being less evident in high risk patients. Moving from cohort studies to the analysis of a series from clinical trials contributed to increase the robustness of TILs as a biomarker. The employment of high TIL densities as an indicator of good prognosis in early-stage colon cancers is strongly advisable, while in late-stage colon cancers the employment as an indicator of good responsiveness to post-surgical therapy requires refinement. It remains to be clarified whether TILs could help in identifying those patients with node-positive cancers to whom adjuvant treatment could be spared, at least in low-risk groups as defined by the TNM staging system.