CXCR4 inhibition in tumor microenvironment facilitates anti-programmed death receptor-1 immunotherapy in sorafenib-treated hepatocellular carcinoma in mice

Drug resistance in TKI therapy for hepatocellular carcinoma: Mechanisms and strategies

Tyrosine kinase inhibitors (TKIs) are such as sorafenib the first-line therapeutic drugs for patients with advanced hepatocellular carcinoma. However, patients with TKI-resistant advanced liver cancer are insensitive to TKI treatment, resulting in limited survival benefits. This paper comprehensively reviewed the mechanisms underlying TKI resistance in hepatocytes, investigating activation of tumor signaling pathways, epigenetic regulation, tumor microenvironment, and metabolic reprogramming. Based on resistance mechanisms, it also reviews preclinical and clinical studies of drug resistance strategies and summarizes targeted therapy combined with immunotherapy currently in investigational clinical trials. Understanding the interactions and clinical studies of these resistance mechanisms offers new hope for improving and prolonging patient survival.

A Chemotherapy Response-Related Gene Signature and DNAJC8 as Key Mediators of Hepatocellular Carcinoma Progression and Drug Resistance

Background

Chemotherapy resistance in hepatocellular carcinoma presents a significant challenge to improved patient outcomes. Identifying genes associated with chemotherapy response can enhance treatment strategies and prognostic models.

Methods

We analyzed the expression of chemotherapy response-related gene in hepatocellular carcinoma using TCGA and GSE109211 cohorts. We constructed a prognostic model using Least Absolute Shrinkage and Selection Operator (LASSO) analysis and assessed its efficacy using Kaplan-Meier survival analysis. Additionally, we evaluated the immune landscape and gene mutation profiles between different chemotherapy response-related gene (CRRG) subtypes. DNAJC8's role in hepatocellular carcinoma cell functions and chemotherapy resistance was further explored through gene knockdown experiments in vitro and in vivo.

Results

Differential expression analysis identified 220 common genes associated with chemotherapy response. The prognostic model incorporating seven key genes efficiently distinguished responders from non-responders and indicated poorer overall survival for the CRRG-high subtype. The CRRG value correlated with tumor stage and grade, and mutation profiles showed distinct patterns between CRRG subtypes. The CRRG-high subtype exhibited an immune-suppressive phenotype with higher expression of PD-L1 and CTLA-4. High DNAJC8 expression was linked to poor prognosis in multiple cohorts. Knocking down DNAJC8 significantly inhibited hepatocellular carcinoma cell proliferation, migration, invasion, and reduced sorafenib IC50.

Conclusion

The seven-gene CRRG model, particularly DNAJC8, holds potential for predicting chemotherapy response and serves as a therapeutic target in hepatocellular carcinoma.

CXCR4-targeted ultrasound microbubbles for imaging and enhanced chemotherapy/Immunotherapy in liver cancer

Ultrasound molecular imaging is an innovative imaging modality that combines ultrasound with molecular probes to observe live biological processes at the cellular and molecular levels. C-X-C chemokine receptor type 4 (CXCR4) is a specific target in liver tumors and plays a crucial role in promoting tumor growth, invasion, metastasis, and angiogenesis. This study pioneered the use of CXCR4-targeted ultrasound molecular imaging for visualized antitumor therapy and investigated the potential of CXCR4-targeted microbubbles (MBs) in sensitizing liver tumor treatment. CXCR4-targeted MBs demonstrated high ligands conjugation efficiency to vascular endothelial cells (99.77 ± 0.15 %) and significantly inhibited the migration and invasion of Hepa1-6 cells. Molecular CEUS imaging results indicated that the MBs carrying LFC131 peptides facilitated site-specific recognition in BALB/c mice bearing Hep G2 tumors. After the 2-week of chemotherapy, ultrasound molecular imaging signals were significantly reduced in liver cancer when using CXCR4-targeted MBs compared to the SonoVue group which were corroborated by quantitative immunohistochemical grading of CXCR4 expression. In liver cancer immunotherapy, the anti-PD-L1 mAb + CXCR4-targeted MBs group yielded a remarkable tumor inhibition rate (94.6 %) with increased CD8+ T-cell infiltration and decreased FOXP3+ regulatory T cells. Bulk RNA-seq analysis and animal experiment confirmed that anti-PD-L1 mAb combined with CXCR4-targeted MBs effectively induced a robust immune response in liver cancer. These findings establish a solid foundation for future molecular CEUS imaging applications and the development of sensitization strategies for liver cancer therapy. STATEMENT OF SIGNIFICANCE: Ultrasound molecular imaging plays a pivotal role in advancing precision medicine by optimizing tumor diagnosis and treatment. This study pioneers ultrasound molecular imaging in liver tumor therapy using CXCR4-targeted microbubbles (MBs) conjugated with LFC131 peptides. Achieving 99.77 % ligand binding efficiency, the CXCR4-targeted MBs group suppressed tumor migration and enabled precise molecular imaging validated by immunohistochemistry. Moreover, the integration of CXCR4-targeted MBs with anti-PD-L1 immunotherapy resulted in a remarkable tumor inhibition rate of 94.6 %, accompanied by increased CD8+ T cells and decreased FOXP3+ regulatory T cells. These findings underscore the dual role of CXCR4-targeted MBs in both imaging and enhancing chemotherapy/immunotherapy, establishing a foundational framework for the future advancement of molecular imaging-guided liver cancer treatment.

CXCR4 antagonist-loaded nanoparticles reprogram the tumor microenvironment and enhance immunotherapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer death that has limited treatment options for advanced stages. Although PD-1 inhibitors such as nivolumab and pembrolizumab have been approved for advanced HCC treatment, their effectiveness is often hampered by the immunosuppressive tumor microenvironment (TME), which is due to hypoxia-driven CXCL12/CXCR4 axis activation. In this study, we developed 807-NPs, lipid-coated tannic acid (TA) nanoparticles that encapsulate BPRCX807, a potent CXCR4 antagonist to target HCC. 807-NPs enhance the pharmacokinetics and improve the tumor availability of BPRCX807 without causing systemic toxicity. Our findings show that 807-NPs block the CXCR4/CXCL12 pathway, inhibiting Akt and mTOR activation in HCC cells and M2 macrophages and promoting their repolarization toward the antitumor M1 phenotype. In orthotopic murine HCC models, systemic administration of 807-NPs significantly remodeled the immunosuppressive TME by reprogramming tumor-associated macrophages (TAMs) toward an immunostimulatory phenotype and promoting cytotoxic T-cell infiltration into tumors. This led to suppressed primary tumor growth and metastasis, while enhancing the efficacy of cancer immunotherapies, including PD-1 blockade and whole-cancer cell vaccines, by promoting T-cell activation. Our work demonstrates the potential of using nanotechnology to deliver CXCR4 antagonists for cancer immunotherapy.

Circulating mitochondrial DNA promotes M2 polarization of tumor associated macrophages and HCC resistance to sorafenib

Mitochondrial damage-associated molecular patterns (DAMPs) including mitochondrial DNA (mtDNA), TFAM (transcription factor A, mitochondrial), and ATP, which play crucial roles in the regulation of inflammatory environment in human diseases. However, the role of mitochondrial DAMPs in regulating tumor microenvironment (TME) remains unclear. Herein, we demonstrate that infiltration of M2-type tumor-associated macrophages (TAMs) was correlated with the resistance of hepatocellular carcinoma (HCC) to sorafenib. We found that cell-free mtDNA in the plasma was significantly increased in sorafenib-resistant HCC mice. Sorafenib induced mitochondrial dysfunction and promoted the release of mtDNA into extracellular matrix of HCC. Macrophages retook the mtDNA in the TME of HCC, activated TLR9 signaling, and promoted the activation of NF-κB and the polarization of TAMs into M2. Application of DNase I to digest mtDNA or depletion of macrophages with clodronate liposomes reduced M2 macrophage infiltration, decreased the growth of HCC, and sensitized the tumors to sorafenib. Furthermore, we showed that blocking the activation of TLR9 enhanced the therapeutic effect of sorafenib in HCC. Together, we demonstrate that sorafenib treatment leads to the release of mtDNA into TME in HCC, which in turn facilitates the polarization of TAMs into M2 macrophages through TLR9 activation and aggravates the resistance of HCC to sorafenib. Our study reveals a novel mechanism underlying circulating mtDAMPs in remodeling the HCC microenvironment by reprograming the TAMs and provides a new strategy for improving the therapeutic effect of sorafenib and overcoming its resistance in HCC.

Precision models in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents a global health challenge, and ranks among one of the most prevalent and deadliest cancers worldwide. Therapeutic advances have expanded the treatment armamentarium for patients with advanced HCC, but obstacles remain. Precision oncology, which aims to match specific therapies to patients who have tumours with particular features, holds great promise. However, its implementation has been hindered by the existence of numerous 'HCC influencers' that contribute to the high inter-patient heterogeneity. HCC influencers include tumour-related characteristics, such as genetic alterations, immune infiltration, stromal composition and aetiology, and patient-specific factors, such as sex, age, germline variants and the microbiome. This Review delves into the intricate world of HCC, describing the most innovative model systems that can be harnessed to identify precision and/or personalized therapies. We provide examples of how different models have been used to nominate candidate biomarkers, their limitations and strategies to optimize such models. We also highlight the importance of reproducing distinct HCC influencers in a flexible and modular way, with the aim of dissecting their relative contribution to therapy response. Next-generation HCC models will pave the way for faster discovery of precision therapies for patients with advanced HCC.

Inhibiting CXCR4 reduces immunosuppressive effects of myeloid cells in breast cancer immunotherapy

Patients with triple negative breast cancer (TNBC) show only modest response rates to immune checkpoint inhibitor immunotherapy, motivating ongoing efforts to identify approaches to boost efficacy. Using an immunocompetent mouse model of TNBC, we investigated combination therapy with an anti-PD-1 immunotherapy antibody plus balixafortide, a cyclic peptide inhibitor of CXCR4. Cell-based assays demonstrated that balixafortide functions as an inverse agonist, establishing a mode of action distinct from most compounds targeting CXCR4. Combination anti-PD-1 plus balixafortide significantly reduced growth of orthotopic tumors and extended overall survival relative to single agent therapy or vehicle. Adding balixafortide to anti-PD-1 increased numbers of tertiary lymphoid structures, a marker of local tumor immune responses associated with favorable response to immunotherapy in TNBC. Single cell RNA sequencing revealed that combination anti-PD-1 plus balixafortide reduced T cell exhaustion and increased markers of effector T cell activity. Combination therapy also reduced signatures of immunosuppressive myeloid derived suppressor cells (MDSCs) in tumors. MDSCs isolated from mice treated with anti-PD-1 plus balixafortide showed reduced inhibition of T cell proliferation following ex vivo stimulation. These studies demonstrate that combining inhibition of CXCR4 with anti-PD-1 to enhances responses to checkpoint inhibitor immunotherapy in TNBC, supporting future clinical trials.

Combination CXCR4 and PD-1 Blockade Enhances Intratumoral Dendritic Cell Activation and Immune Responses Against Hepatocellular Carcinoma

Immune checkpoint inhibitors have revolutionized the treatment of unresectable hepatocellular carcinoma (HCC), but their impressive efficacy is seen in just a fraction of patients. One key mechanism of immunotherapy resistance is the paucity of dendritic cells (DC) in liver malignancies. In this study, we tested combination blockade of PD-1 and CXCR4, a receptor for CXCL12, a pleiotropic factor that mediates immunosuppression in tumors. Using orthotopic grafted and autochthonous HCC models with underlying liver damage, we evaluated treatment feasibility and efficacy. In addition, we examined the effects of treatment using immunofluorescence, flow cytometric analysis of DCs in vivo and in vitro, and RNA sequencing. The combination anti-CXCR4 and anti-PD-1 therapy was safe and significantly inhibited tumor growth and prolonged survival in all murine preclinical models of HCC tested. The combination treatment successfully reprogrammed antigen-presenting cells, revealing the potential role of conventional type 1 DCs (cDC1) in the HCC microenvironment. Moreover, DC reprogramming enhanced anticancer immunity by facilitating CD8+ T-cell accumulation and activation in the HCC tissue. The effectiveness of anti-CXCR4/PD-1 therapy was compromised entirely in Batf3 knockout mice deficient in cDC1s. Thus, combined CXCR4/PD-1 blockade can reprogram intratumoral cDC1s and holds the potential to potentiate antitumor immune response against HCC.

Spatial‒temporal heterogeneities of liver cancer and the discovery of the invasive zone

Solid tumours are intricate and highly heterogeneous ecosystems, which grow in and invade normal organs. Their progression is mediated by cancer cells' interaction with different cell types, such as immune cells, stromal cells and endothelial cells, and with the extracellular matrix. Owing to its high incidence, aggressive growth and resistance to local and systemic treatments, liver cancer has particularly high mortality rates worldwide. In recent decades, spatial heterogeneity has garnered significant attention as an unfavourable biological characteristic of the tumour microenvironment, prompting extensive research into its role in liver tumour development. Advances in spatial omics have facilitated the detailed spatial analysis of cell types, states and cell‒cell interactions, allowing a thorough understanding of the spatial and temporal heterogeneities of tumour microenvironment and informing the development of novel therapeutic approaches. This review illustrates the latest discovery of the invasive zone, and systematically introduced specific macroscopic spatial heterogeneities, pathological spatial heterogeneities and tumour microenvironment heterogeneities of liver cancer.

T-cell Receptor Repertoire Analysis in the Context of Transarterial Chemoembolization Synergy with Systemic Therapy for Hepatocellular Carcinoma

T-cell receptor (TCR) sequencing provides a novel platform for insight into and characterization of intricate T-cell profiles, advancing the understanding of tumor immune heterogeneity. Recently, transarterial chemoembolization (TACE) combined with systemic therapy has become the recommended regimen for advanced hepatocellular carcinoma. The regulation of the immune microenvironment after TACE and its impact on tumor progression and recurrence has been a focus of research. By examining and tracking fluctuations in the TCR repertoire following combination treatment, novel perspectives on the modulation of the tumor microenvironment post-TACE and the underlying mechanisms governing tumor progression and recurrence can be gained. Clarifying the distinctive metrics and dynamic alterations of the TCR repertoire within the context of combination therapy is imperative for understanding the mechanisms of anti-tumor immunity, assessing efficacy, exploiting novel treatments, and further advancing precision oncology in the treatment of hepatocellular carcinoma. In this review, we initially summarized the fundamental characteristics of TCR repertoire and depicted immune microenvironment remodeling after TACE. Ultimately, we illustrated the prospective applications of TCR repertoires in TACE combined with systemic therapy.

Sorafenib enhanced the function of myeloid-derived suppressor cells in hepatocellular carcinoma by facilitating PPARα-mediated fatty acid oxidation

BACKGROUND

Sorafenib, an FDA-approved drug for advanced hepatocellular carcinoma (HCC), faces resistance issues, partly due to myeloid-derived suppressor cells (MDSCs) that enhance immunosuppression in the tumor microenvironment (TME).

METHODS

Various murine HCC cell lines and MDSCs were used in a series of in vitro and in vivo experiments. These included subcutaneous tumor models, cell viability assays, flow cytometry, immunohistochemistry, and RNA sequencing. MDSCs were analyzed for chemotaxis, immunosuppressive functions, fatty acid oxidation (FAO), and PPARα expression. The impact of sorafenib on tumor growth, MDSC infiltration, differentiation, and immunosuppressive function was assessed, alongside the modulation of these processes by PPARα.

RESULTS

Here, we revealed increased infiltration and enhanced function of MDSCs in TME after treatment with sorafenib. Moreover, our results indicated that sorafenib induced the accumulation of MDSCs mediated by CCR2, and pharmacological blockade of CCR2 markedly reduced MDSCs migration and tumor growth. Mechanistically, sorafenib promoted the effect and fatty acid uptake ability of MDSCs and modulated peroxisome proliferator-activated receptor α (PPARα)-mediated fatty acid oxidation (FAO). In addition, tumor-bearing mice fed a high-fat diet (HFD) at the beginning of sorafenib administration had worse outcomes than mice fed a regular diet. Genetic deficiency of PPARα weakens the effect of sorafenib on MDSCs in mice with HCC. Pharmacological inhibition of PPARα has a synergistic anti-tumor effect with sorafenib, which is attenuated by the inhibition of MDSCs. Mechanistically, sorafenib significantly inhibited the differentiation of macrophages by upregulating PPARα expression and suppressing the PU.1-CSF1R pathway.

CONCLUSION

Overall, our study demonstrated that sorafenib enhanced the function of MDSCs by facilitating PPARα-mediated FAO and further augmenting sorafenib resistance, which sheds light on dietary management and improves the therapeutic response in HCC.

Current Perspectives of Immunotherapy for Hepatocellular Carcinoma

Hepatocellular carcinoma is the sixth most common tumor and the third leading cause of cancer death worldwide. It ranks fourth in the spectrum of malignant tumor incidence and second in the order of death from major malignant tumors in China. Hepatocellular carcinoma is a complex ecosystem containing non-tumor cells (mainly immune-related cells), and its immunotherapy can stimulate the recognition of specific tumor antigens, inhibit the proliferation of cancer cells, and produce over-memory lymphocytes, which can prevent recurrence. So, immunotherapy of hepatocellular carcinoma is increasingly becoming a research hotspot in liver cancer treatment. With the intensive research in recent years, great progress has been made in immunotherapy for hepatocellular carcinoma, including immune checkpoint inhibitors, pericyte therapy, vaccination, and antiviral therapy. In addition, the study found that the therapeutic effect of combination therapy was enhanced compared to monotherapy. This review summarizes the most prominent immunotherapies currently available for the clinical treatment of patients with HCC and the main opportunities and challenges facing HCC research.

Heterogeneity of tumor-associated neutrophils in hepatocellular carcinoma

Neutrophils are the most abundant cell type in human blood and play a crucial role in the immune system and development of tumors. This review begins with the generation and development of neutrophils, traces their release from the bone marrow into the bloodstream, and finally discusses their role in the hepatocellular carcinoma (HCC) microenvironment. It elaborates in detail the mechanisms by which tumor-associated neutrophils (TANs) exert antitumor or protumor effects under the influence of various mediators in the tumor microenvironment. Neutrophils can exert antitumor effects through direct cytotoxic action. However, they can also accelerate the formation and progression of HCC by being recruited and infiltrated, promoting tumor angiogenesis, and maintaining an immunosuppressive microenvironment. Therefore, based on the heterogeneity and plasticity of neutrophils in tumor development, this review summarizes the current immunotherapies targeting TANs, discusses potential opportunities and challenges, and provides new insights into exploring more promising strategies for treating HCC.

Immune Microenvironment and the Effect of Vascular Endothelial Growth Factor Inhibition in Hepatocellular Carcinoma

Systemic therapy for unresectable hepatocellular carcinoma (HCC) has progressed with the development of multiple kinases, such as vascular endothelial growth factor (VEGF) signaling, targeting cancer growth and angiogenesis. Additionally, the efficacy of sorafenib, regorafenib, lenvatinib, ramucirumab, and cabozantinib has been demonstrated in various clinical trials, and they are now widely used in clinical practice. Furthermore, the development of effective immune checkpoint inhibitors has progressed in systemic therapy for unresectable HCC, and atezolizumab + bevacizumab (atezo/bev) therapy and durvalumab + tremelimumab therapy are now recommended as first-line treatment. Atezo/bev therapy, which combines an anti-programmed cell death 1 ligand 1 antibody with an anti-VEGF antibody, is the first cancer immunotherapy to demonstrate efficacy against unresectable HCC. With the increasing popularity of these treatments, VEGF inhibition is attracting attention from the perspective of its anti-angiogenic effects and impact on the cancer-immune cycle. In this review, we outline the role of VEGF in the tumor immune microenvironment and cancer immune cycle in HCC and outline the potential immune regulatory mechanisms of VEGF. Furthermore, we consider the potential significance of the dual inhibition of angiogenesis and immune-related molecules by VEGF, and ultimately aim to clarify the latest treatment strategies that maximizes efficacy.

The power of many: Multilevel targeting of representative chemokine and metabolite GPCRs in personalized cancer therapy

G protein-coupled receptors (GPCRs) are vital cell surface receptors that govern a myriad of physiological functions. Despite their crucial role in regulating antitumor immunity and tumorigenesis, therapeutic applications targeting GPCRs in oncology are currently limited. This review offers a focused examination of selected protumorigenic chemokine and metabolite-sensing GPCRs. Specifically, the review highlights five GPCRs able to orchestrate tumor immunobiology at three main levels: tumor immunity, cancer cell expansion, and blood vessel development. The review culminates by illuminating emerging therapies and discussing innovative strategies to harness the full potential of GPCR-targeted treatments, by applying a multireceptor and patient-specific logic.

Multifaceted Aspects of Dysfunctional Myelopoiesis in Cancer and Therapeutic Perspectives with Focus on HCC

Myelopoiesis provides for the formation and continued renewal of cells belonging primarily to the innate immune system. It is a highly plastic process that secures the response to external and internal stimuli to face acute and changing needs. Infections and chronic diseases including cancer can modulate it by producing several factors, impacting proliferation and differentiation programs. While the lymphocytic compartment has attracted major attention due to the role of adaptive immunity in anticancer immune response, in recent years, research has found convincing evidence that confirms the importance of innate immunity and the key function played by emergency myelopoiesis. Due to cancer's ability to manipulate myelopoiesis to its own advantage, the purpose of this review is to outline myelopoiesis processes within the tumor microenvironment and suggest possible therapeutic lines of research to restore the physiological functioning of the host's immune system, with a special outlook on hepatocellular carcinoma (HCC).

[Research Advances in the Roles of High-Altitude Hypoxic Stress in Hepatocellular Carcinoma]

Hepatocellular carcinoma (HCC), one of the most prevalent malignant tumors causing the highest mortality globally, imposes an especially heavy burden of disease in China. Individuals living in high-altitude areas have a lower incidence of and mortality resulting from HCC compared with those in low-altitude regions do, potentially due to adaptive evolution in responses to hypoxic stress. Notably, high-altitude hypoxic stress is associated with the development and progression of HCC. Hypoxic stress may be involved in the development and progression of HCC by modulating the senescence, apoptosis, metabolism, tumor microenvironment, and tumor immunity of HCC cells. Additionally, the latest clinical findings indicate that high-altitude hypoxic environment has a significant impact on liver regeneration after HCC resection surgery. However, there is still a debate going on regarding whether high-altitude hypoxic stress promotes or inhibits the progression of HCC. This review covers three main aspects, the impact of adaptive evolution to high-altitude hypoxic stress on the development and progression of HCC in long-term residents of high-altitude areas, the effects of high-altitude hypoxic stress on the senescence, apoptosis, metabolism, tumor microenvironment, tumor metabolism, and tumor immunity of HCC cells, and the effect of high-altitude hypoxic stress on liver regeneration after HCC resection. We discussed the effect of changes in oxygen concentrations, cellular context, and tissue microenvironment on HCC development and progression. Moreover, we highlighted the potential for using research findings on mechanisms underlying high-altitude hypoxic stress to optimize HCC treatment strategies.

Sorafenib-induced macrophage extracellular traps via ARHGDIG/IL4/PADI4 axis confer drug resistance through inhibiting ferroptosis in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common as well as leading causes of mortality worldwide, and sorafenib is the first-line treatment in HCC patients. Unfortunately, drug resistance to sorafenib often develops. However, the underlying mechanism remains unclear. Here, we reveal the important role of macrophage extracellular traps (METs)-mediated crosstalk between macrophages and tumor cells in sorafenib resistance.

METHODS

METs in HCC tumor tissues were detected using immunofluorescence. The concentrations of MPO-DNA, elastase and cytokines were measured using ELISA. The mRNA expression levels of genes were confirmed by qRT-PCR. The siRNAs were conducted to knock ARHGDIG in Hepa1-6 and Hep3B cells. Western Blot assay was performed to determine protein expression of Rho GDP dissociation inhibitor gamma (ARHGDIG, or RHOGDI-3), PADI2, and PADI4. Cell viability and migration were evaluated by CCK-8 assay and transwell assay, respectively. Cell ferroptosis was assessed by measurement of Fe2+ concentration, flow cytometry assay of lipid ROS, and western blot assay of GPX4. The functions of sorafenib, DNase I, IL4 neutralization antibody and GPX4 in tumor growth were explored through in vivo experiments.

RESULTS

Sorafenib induced MET formation in M2 macrophages rather than M1 macrophages derived from both human and mice. In Hepa1-6 HCC mice, METs clearance by DNase I improved response to sorafenib therapy, detected by tumor weight, tumor growth curve, tumor volume, and survival. By screening candidate cytokines that affect macrophage function, we found that sorafenib-promoting IL4 secretion by HCC cells plays a crucial role in sorafenib-induced MET formation. Understanding the critical role of IL4 in sorafenib-induced MET formation led us to find that IL4 neutralization significantly improved the efficiency of sorafenib in HCC models. Mechanistically, we discovered that sorafenib increased the expression of ARHGDIG in HCC cells, which led to the release of IL4. In M2 macrophages, IL4 triggered MET formation by elevating the mRNA and protein expression of peptidyl arginine deiminase 4 (PADI4) rather than PADI2. In HCC models, GSK484 inhibition of PADI4 could consistently weaken sorafenib resistance and improve sorafenib efficiency. Importantly, we discovered that METs contribute to sorafenib resistance by inhibiting the ferroptosis of HCC cells. Meanwhile, PADI4 inhibition or DNase I could reverse the sorafenib resistance caused by METs-inhibiting ferroptosis of HCC cells.

CONCLUSION

Our study concludes that sorafenib-induced METs inhibit the ferroptosis of tumor cells, suggesting that targeting the IL4/PADI4/METs axis in HCC could reduce or prevent sorafenib resistance.

Advancing Hepatocellular Carcinoma Management Through Peritumoral Radiomics: Enhancing Diagnosis, Treatment, and Prognosis

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and is associated with high mortality rates due to late detection and aggressive progression. Peritumoral radiomics, an emerging technique that quantitatively analyzes the tissue surrounding the tumor, has shown significant potential in enhancing the management of HCC. This paper examines the role of peritumoral radiomics in improving diagnostic accuracy, guiding personalized treatment strategies, and refining prognostic assessments. By offering unique insights into the tumor microenvironment, peritumoral radiomics enables more precise patient stratification and informs clinical decision-making. However, the integration of peritumoral radiomics into routine clinical practice faces several challenges. Addressing these challenges through continued research and innovation is crucial for the successful implementation of peritumoral radiomics in HCC management, ultimately leading to improved patient outcomes.

Small-molecule-based targeted therapy in liver cancer

Liver cancer is one of the most prevalent malignant tumors worldwide. According to the Barcelona Clinic Liver Cancer staging criteria, clinical guidelines provide tutorials to clinical management of liver cancer at their individual stages. However, most patients diagnosed with liver cancer are at advanced stage; therefore, many researchers conduct investigations on targeted therapy, aiming to improve the overall survival of these patients. To date, small-molecule-based targeted therapies are highly recommended (first line: sorafenib and lenvatinib; second line: regorafenib and cabozantinib) by current the clinical guidelines of the American Society of Clinical Oncology, European Society for Medical Oncology, and National Comprehensive Cancer Network. Herein, we summarize the small-molecule-based targeted therapies in liver cancer, including the approved and preclinical therapies as well as the therapies under clinical trials, and introduce their history of discovery, clinical trials, indications, and molecular mechanisms. For drug resistance, the revealed mechanisms of action and the combination therapies are also discussed. In fact, the known small-molecule-based therapies still have limited clinical benefits to liver cancer patients. Therefore, we analyze the current status and give our ideas for the urgent issues and future directions in this field, suggesting clues for novel techniques in liver cancer treatment.

A quartet of cancer stem cell niches in hepatocellular carcinoma

Hepatocellular Carcinoma (HCC), the most prevalent type of primary liver cancer, is known for its aggressive behavior and poor prognosis. The Cancer Stem Cell theory, which postulates the presence of a small population of self-renewing cells called Cancer Stem Cells (CSCs), provides insights into various clinical and molecular features of HCC such as tumor heterogeneity, metabolic adaptability, therapy resistance, and recurrence. These CSCs are nurtured in the tumor microenvironment (TME), where a mix of internal and external factors creates a tumor-supportive niche that is continuously evolving both spatially and temporally, thus enhancing the tumor's complexity. This review details the origins of hepatic CSCs (HCSCs) and the factors influencing their stem-like qualities. It highlights the reciprocal crosstalk between HCSCs and the TME (hypoxic, vascular, invasive, and immune niches), exploring the signaling pathways involved and how these interactions control the malignant traits of CSCs. Additionally, it discusses potential therapeutic approaches targeting the HCSC niche and their possible uses in clinical practice.

Tumor‑associated macrophages activated in the tumor environment of hepatocellular carcinoma: Characterization and treatment (Review)

Hepatocellular carcinoma (HCC) tissue is rich in dendritic cells, T cells, B cells, macrophages, natural killer cells and cellular stroma. Together they form the tumor microenvironment (TME), which is also rich in numerous cytokines. Tumor‑associated macrophages (TAMs) are involved in the regulation of tumor development. TAMs in HCC receive stimuli in different directions, polarize in different directions and release different cytokines to regulate the development of HCC. TAMs are mostly divided into two cell phenotypes: M1 and M2. M1 TAMs secrete pro‑inflammatory mediators, and M2 TAMs secrete a variety of anti‑inflammatory and pro‑tumorigenic substances. The TAM polarization in HCC tumors is M2. Both direct and indirect methods for TAMs to regulate the development of HCC are discussed. TAMs indirectly support HCC development by promoting peripheral angiogenesis and regulating the immune microenvironment of the TME. In terms of the direct regulation between TAMs and HCC cells, the present review mainly focuses on the molecular mechanism. TAMs are involved in both the proliferation and apoptosis of HCC cells to regulate the quantitative changes of HCC, and stimulate the related invasive migratory ability and cell stemness of HCC cells. The present review aims to identify immunotherapeutic options based on the mechanisms of TAMs in the TME of HCC.

Single-cell and bulk RNA-sequencing reveal SPP1 and CXCL12 as cell-to-cell communication markers to predict prognosis in lung adenocarcinoma

Lung adenocarcinoma (LUAD) generally presents as an immunosuppressive microenvironment. The characteristics of cell-to-cell communication in the LUAD microenvironment has been unclear. In this study, the LUAD bulk RNA-seq data and single-cell RNA-seq data were retrieved from public dataset. Differential expression genes (DEGs) between LUAD tumor and adjacent non-tumor tissues were calculated by limma algorithm, and then detected by PPI, KEGG, and GO analysis. Cell-cell interactions were explored using the single-cell RNA-seq data. Finally, the first 15 CytoHubba genes were used to establish related pathways and these pathways were used to characterize the immune-related ligands and their receptors in LUAD. Our analyses showed that monocytes or macrophages interact with tissue stem cells and NK cells via SPP1 signaling pathway and tissue stem cells interact with T and B cells via CXCL signaling pathway in different states. Hub genes of SPP1 participated in SPP1 signaling pathway, which was negatively correlated with CD4+ T cell and CD8+ T cell. The expression of SPP1 in LUAD tumor tissues was negatively correlated with the prognosis. While CXCL12 participated in CXCL signaling pathway, which was positively correlated with CD4+ T cell and CD8+ T cell. The role of CXCL12 in LUAD tumor tissues exhibits an opposite effect to that of SPP1. This study reveals that tumor-associated monocytes or macrophages may affect tumor progression. Moreover, the SPP1 and CXCL12 may be the critic genes of cell-to-cell communication in LUAD, and targeting these pathways may provide a new molecular mechanism for the treatment of LUAD.

CXCL12-loaded-hydrogel (CLG): A new device for metastatic circulating tumor cells (CTCs) capturing and characterization

Background

Circulating Tumor Cells (CTCs) represent a small, heterogeneous population that comprise the minority of cells able to develop metastasis. To trap and characterize CTCs with metastatic attitude, a CXCL12-loaded hyaluronic-gel (CLG) was developed. CXCR4+cells with invasive capability would infiltrate CLG.

Methods

Human colon, renal, lung and ovarian cancer cells (HT29, A498, H460 and OVCAR8 respectively) were seeded on 150 μl Empty Gels (EG) or 300 ng/ml CXCL12 loaded gel (CLG) and allowed to infiltrate for 16 h. Gels were then digested and fixed with 2 % FA-HAse for human cancer cell enumeration or digested with HAse and cancer cells recovered. CLG-recovered cells migrated toward CXCL12 and were tested for colonies/spheres formation. Moreover, CXCR4, E-Cadherin and Vimentin expression was assessed through flow cytometry and RT-PCR. The clinical trial "TRAP4MET" recruited 48 metastatic/advanced cancer patients (8 OC, 8 LC, 8 GBM, 8 EC, 8 RCC and 8 EC). 10 cc whole blood were devoted to PBMCs extraction (7 cc) and ScreenCell™ filters (3 cc) CTCs evaluation. Ficoll-isolated patient's PBMCs were seeded over CLG and allowed to infiltrate for 16 h; gels were digested and fixed with 2 % FA-HAse, cells stained and DAPI+/CD45-/pan-CK + cells enumerated as CTCs.

Results

Human cancer cells infiltrate CLG more efficiently than EG (CLG/EG ratio 1.25 for HT29/1.58 for A498/1.71 for H460 and 2.83 for OVCAR8). CLG-recovered HT29 cells display hybrid-mesenchymal features [low E-cadherin (40 %) and high vimentin (235 %) as compared to HT29], CXCR4 two-fold higher than HT29, efficiently migrate toward CXCL12 (two-fold higher than HT29) and developed higher number of colonies (171 ± 21 for HT29-CLG vs 131 ± 8 colonies for HT29)/larger spheres (spheroid area: 26561 ± 6142 μm2 for HT29-CLG vs 20297 ± 7238 for HT29). In TRAP4MET clinical trial, CLG-CTCs were isolated in 8/8 patients with OC, 6/8 with LC, 6/8 with CRC, 8/8 with EC, 8/8 with RCC cancer and 5/8 with GBM. Interestingly, in OC, LC and GBM, CLG isolated higher number of CTCs as compared to the conventional ScreenCell™ (CLG/SC ratio = 1.88 for OC, 2.47 for LC and 11.89 for GBM). Bland and Altman blot analysis and Passing and Bablok regression analysis showed concordance between the methodological approaches but indicate that SC and CLG are not superimposable suggesting that the two systems select cells with different features.

Conclusion

CLG might represent a new and easy tool to isolate invasive CTCs in multiple cancers such as OC, LC and GBM at today orphan of reliable methods to consistently detect CTCs.

The current status and future of targeted-immune combination for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers and the third leading cause of death worldwide. surgery, transarterial chemoembolization (TACE), systemic therapy, local ablation therapy, radiotherapy, and targeted drug therapy with agents such as sorafenib. However, the tumor microenvironment of liver cancer has a strong immunosuppressive effect. Therefore, new treatments for liver cancer are still necessary. Immune checkpoint molecules, such as programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen-4 (CTLA-4), along with high levels of immunosuppressive cytokines, induce T cell inhibition and are key mechanisms of immune escape in HCC. Recently, immunotherapy based on immune checkpoint inhibitors (ICIs) as monotherapy or in combination with tyrosine kinase inhibitors, anti-angiogenesis drugs, chemotherapy agents, and topical therapies has offered great promise in the treatment of liver cancer. In this review, we discuss the latest advances in ICIs combined with targeted drugs (targeted-immune combination) and other targeted-immune combination regimens for the treatment of patients with advanced HCC (aHCC) or unresectable HCC (uHCC), and provide an outlook on future prospects. The literature reviewed spans the last five years and includes studies identified using keywords such as "hepatocellular carcinoma," "immune checkpoint inhibitors," "targeted therapy," "combination therapy," and "immunotherapy".

Melatonin enhances the efficacy of anti-PD-L1 by improving hypoxia in residual tumors after insufficient radiofrequency ablation

The hypoxic microenvironment and inflammatory state of residual tumors caused by insufficient radiofrequency ablation (iRFA) are major reasons for rapid tumor progression and pose challenges for immunotherapy. We retrospectively analyzed the clinical data of patients with hepatocellular carcinoma (HCC) treated with RFA and observed that iRFA was associated with poor survival outcomes and progression-free survival. Using an orthotopic HCC mouse model and a colorectal liver metastasis model, we observed that treatment with melatonin after iRFA reduced tumor growth and metastasis and achieved the best outcomes when combined with anti-programmed death-ligand 1 (anti-PD-L1) therapy. In mechanism, melatonin inhibited the expression of epithelial-mesenchymal transitions, hypoxia-inducible factor (HIF)-1α, and PD-L1 in tumor cells after iRFA. Flow cytometry revealed that melatonin reduced the proportion of myeloid-derived suppressor cells and increased the proportion of CD8+ T cells. Transcriptomic analysis revealed an upregulation of immune-activated function-related genes in residual tumors. These findings demonstrated that melatonin can reverse hypoxia and iRFA-induced inflammation, thereby overcoming the immunosuppressive tumor microenvironment (TME) and enhancing the efficacy of immunotherapy.

Advancements in microenvironment-based therapies: transforming the landscape of multiple myeloma treatment

Multiple myeloma (MM) is the most prevalent malignant monoclonal disease of plasma cells. There is mounting evidence that interactions with the bone marrow (BM) niche are essential for the differentiation, proliferation, survival, migration, and treatment resistance of myeloma cells. For this reason, gaining a deeper comprehension of how BM microenvironment compartments interact with myeloma cells may inspire new therapeutic ideas that enhance patient outcomes. This review will concentrate on the most recent findings regarding the mechanisms of interaction between microenvironment and MM and highlight research on treatment targeting the BM niche.

Biological impact and therapeutic implication of tumor-associated macrophages in hepatocellular carcinoma

The tumor microenvironment is a complex space comprised of normal, cancer and immune cells. The macrophages are considered as the most abundant immune cells in tumor microenvironment and their function in tumorigenesis is interesting. Macrophages can be present as M1 and M2 polarization that show anti-cancer and oncogenic activities, respectively. Tumor-associated macrophages (TAMs) mainly have M2 polarization and they increase tumorigenesis due to secretion of factors, cytokines and affecting molecular pathways. Hepatocellular carcinoma (HCC) is among predominant tumors of liver that in spite of understanding its pathogenesis, the role of tumor microenvironment in its progression still requires more attention. The presence of TAMs in HCC causes an increase in growth and invasion of HCC cells and one of the reasons is induction of glycolysis that such metabolic reprogramming makes HCC distinct from normal cells and promotes its malignancy. Since M2 polarization of TAMs stimulates tumorigenesis in HCC, molecular networks regulating M2 to M1 conversion have been highlighted and moreover, drugs and compounds with the ability of targeting TAMs and suppressing their M2 phenotypes or at least their tumorigenesis activity have been utilized. TAMs increase aggressive behavior and biological functions of HCC cells that can result in development of therapy resistance. Macrophages can provide cell-cell communication in HCC by secreting exosomes having various types of biomolecules that transfer among cells and change their activity. Finally, non-coding RNA transcripts can mainly affect polarization of TAMs in HCC.

Anti-VEGFR2-Interferon α Promotes the Infiltration of CD8+ T Cells in Colorectal Cancer by Upregulating the Expression of CCL5

SUMMARY

Immunocytokines are a promising immunotherapeutic approach in cancer therapy. Anti-VEGFR2-interferon α (IFNα) suppressed colorectal cancer (CRC) growth and enhanced CD8 + T-cell infiltration in the tumor microenvironment, exhibiting great clinical translational potential. However, the mechanism of how the anti-VEGFR2-IFNα recruits T cells has not been elucidated. Here, we demonstrated that anti-VEGFR2-IFNα suppressed CRC metastasis and enhanced CD8 + T-cell infiltration. RNA sequencing revealed a transcriptional activation of CCL5 in metastatic CRC cells, which was correlated with T-cell infiltration. IFNα but not anti-VEGFR2 could further upregulate CCL5 in tumors. In immunocompetent mice, both IFNα and anti-VEGFR2-IFNα increased the subset of tumor-infiltrating CD8 + T cells through upregulation of CCL5. Knocking down CCL5 in tumor cells attenuated the infiltration of CD8 + T cells and dampened the antitumor efficacy of anti-VEGFR2-IFNα treatment. We, therefore, propose upregulation of CCL5 is a key to enhance infiltration of CD8 + T cells in metastatic CRC with IFNα and IFNα-based immunocytokine treatments. These findings may help the development of IFNα related immune cytokines for the treatment of less infiltrated tumors.

Mechanisms, combination therapy, and biomarkers in cancer immunotherapy resistance

Anti-programmed death 1/programmed death ligand 1 (anti-PD-1/PD-L1) antibodies exert significant antitumor effects by overcoming tumor cell immune evasion and reversing T-cell exhaustion. However, the emergence of drug resistance causes most patients to respond poorly to these immune checkpoint inhibitors (ICIs). Studies have shown that insufficient T-cell infiltration, lack of PD-1 expression, deficient interferon signaling, loss of tumor antigen presentation, and abnormal lipid metabolism are all considered to be closely associated with immunotherapy resistance. To address drug resistance in tumor immunotherapy, a lot of research has concentrated on developing combination therapy strategies. Currently, ICIs such as anti-PD-1 /PD-L1 antibody combined with chemotherapy and targeted therapy have been approved for clinical treatment. In this review, we analyze the mechanisms of resistance to anti-PD-1/PD-L1 therapy in terms of the tumor microenvironment, gut microbiota, epigenetic regulation, and co-inhibitory immune checkpoint receptors. We also discuss various promising combination therapeutic strategies to address resistance to anti-PD-1/PD-L1 drugs, including combining these therapies with traditional Chinese medicine, non-coding RNAs, targeted therapy, other ICIs, and personalized cancer vaccines. Moreover, we focus on biomarkers that predict resistance to anti-PD-1/PD-L1 therapy as well as combination therapy efficacy. Finally, we suggest ways to further expand the application of immunotherapy through personalized combination strategies using biomarker systems.

Tumor-associated macrophages in anti-PD-1/PD-L1 immunotherapy for hepatocellular carcinoma: recent research progress

Hepatocellular carcinoma (HCC) is one of the cancers that seriously threaten human health. Immunotherapy serves as the mainstay of treatment for HCC patients by targeting the programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) axis. However, the effectiveness of anti-PD-1/PD-L1 treatment is limited when HCC becomes drug-resistant. Tumor-associated macrophages (TAMs) are an important factor in the negative regulation of PD-1 antibody targeted therapy in the tumor microenvironment (TME). Therefore, as an emerging direction in cancer immunotherapy research for the treatment of HCC, it is crucial to elucidate the correlations and mechanisms between TAMs and PD-1/PD-L1-mediated immune tolerance. This paper summarizes the effects of TAMs on the pathogenesis and progression of HCC and their impact on HCC anti-PD-1/PD-L1 immunotherapy, and further explores current potential therapeutic strategies that target TAMs in HCC, including eliminating TAMs in the TME, inhibiting TAMs recruitment to tumors and functionally repolarizing M2-TAMs (tumor-supportive) to M1-TAMs (antitumor type).

Nanomaterials modulate tumor-associated macrophages for the treatment of digestive system tumors

The treatment of digestive system tumors presents challenges, particularly in immunotherapy, owing to the advanced immune tolerance of the digestive system. Nanomaterials have emerged as a promising approach for addressing these challenges. They provide targeted drug delivery, enhanced permeability, high bioavailability, and low toxicity. Additionally, nanomaterials target immunosuppressive cells and reshape the tumor immune microenvironment (TIME). Among the various cells in the TIME, tumor-associated macrophages (TAMs) are the most abundant and play a crucial role in tumor progression. Therefore, investigating the modulation of TAMs by nanomaterials for the treatment of digestive system tumors is of great significance. Here, we present a comprehensive review of the utilization of nanomaterials to modulate TAMs for the treatment of gastric cancer, colorectal cancer, hepatocellular carcinoma, and pancreatic cancer. We also investigated the underlying mechanisms by which nanomaterials modulate TAMs to treat tumors in the digestive system. Furthermore, this review summarizes the role of macrophage-derived nanomaterials in the treatment of digestive system tumors. Overall, this research offers valuable insights into the development of nanomaterials tailored for the treatment of digestive system tumors.

Anlotinib enhanced CD8+ T cell infiltration via induction of CCL5 improves the efficacy of PD-1/PD-L1 blockade therapy in lung cancer

Non-small cell lung cancer (NSCLC) is a leading cause of mortality worldwide and requires effective treatment strategies. Recently, the development of a novel multiple-target tyrosine kinase inhibitor, anlotinib, has drawn increasing attention, especially it shows advantages when combined with PD-1/PD-L1 blockade. However, the mechanism by which anlotinib improves immunotherapy and remodeling of the tumor microenvironment remains unclear. In this study, we found that anlotinib combined with PD-1 blockade significantly inhibited tumor growth and reduced tumor weight in a lung cancer xenograft model compared to any single treatment. Both immunofluorescence and flow cytometry analyses revealed that anlotinib induced a CD8+ T cell dominated tumor microenvironment, which might account for its improved role in immunotherapy. Further investigations showed that CCL5-mediated CD8+ T cell recruitment plays a critical role in anlotinib and PD-1 blockade strategies. The depletion of CD8+ T cells abrogated this process. In conclusion, our findings showed that the combination of anlotinib and PD-1 blockade produced promising effects in the treatment of lung cancer, and that the induction of CCL5-mediced CD8+ T cell recruitment by anlotinib provided a novel mechanism of action.

Synergistic effects of Ω-3 polyunsaturated fatty acid supplementation and programmed cell death protein 1 blockade on tumor growth and immune modulation in a xenograft model of esophageal cancer

BACKGROUND

Esophageal cancer, especially esophageal squamous cell carcinoma (ESCC), remains a significant global health challenge with limited survival rates. This study aimed to elucidate the combined effects of immune-modulating nutrition (IMN) with Ω-3 polyunsaturated fatty acid (PUFA) supplementation and anti-programmed cell death protein 1 (PD-1) treatment on tumor growth and immune responses in a xenograft model of ESCC.

METHODS

A total of 36 C57BL/6 mice were used to construct a xenograft model using the mouse esophageal cancer cell line AKR. Mice were subjected to treatment with anti- PD-1 antibody combined with either Ω-3 PUFA-rich or Ω-3 PUFA-deficient nutrition. Tumor growth, immune markers, cytokine profiles, and metabolic changes were evaluated.

RESULTS

The combination of anti-PD-1 and Ω-3 PUFA supplementation significantly inhibited tumor growth more effectively than anti-PD-1 treatment alone. Enhanced expression of immune markers PD-L1 and CD3 was observed in Ω-3 PUFA-fed mice. Additionally, compared with anti-PD-1 therapy and anti-PD-1 plus Ω-3 PUFA-deficient nutrition, Ω-3 PUFAs intensified alterations in key chemokines and cytokines, including elevated IL-12, IFN-γ, and GM-CSF levels, and reduced CXCL12 levels. However, Ω-3 PUFAs did not significantly alter the glycolysis and tryptophan metabolic program induced by anti-PD-1.

CONCLUSION

Our findings indicated the potential synergetic therapeutic benefits of combining anti-PD-1 treatment with Ω-3 PUFA supplementation in ESCC, which offered promising avenue for further research.

The roles of cancer stem cell-derived secretory factors in shaping the immunosuppressive tumor microenvironment in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide and has a poor prognosis. Although immune checkpoint inhibitors have entered a new era of HCC treatment, their response rates are modest, which can be attributed to the immunosuppressive tumor microenvironment within HCC tumors. Accumulating evidence has shown that tumor growth is fueled by cancer stem cells (CSCs), which contribute to therapeutic resistance to the above treatments. Given that CSCs can regulate cellular and physical factors within the tumor niche by secreting various soluble factors in a paracrine manner, there have been increasing efforts toward understanding the roles of CSC-derived secretory factors in creating an immunosuppressive tumor microenvironment. In this review, we provide an update on how these secretory factors, including growth factors, cytokines, chemokines, and exosomes, contribute to the immunosuppressive TME, which leads to immune resistance. In addition, we present current therapeutic strategies targeting CSC-derived secretory factors and describe future perspectives. In summary, a better understanding of CSC biology in the TME provides a rational therapeutic basis for combination therapy with ICIs for effective HCC treatment.

Macrophages Orchestrate the Liver Tumor Microenvironment

Liver cancer is one of the leading causes of cancer-related mortality. Hepatocellular carcinoma and cholangiocarcinoma are the most common types, and despite numerous advances, therapeutic options still remain poor for these cancer patients. Tumor development and progression strictly depend on a supportive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) are the most abundant immune cells population within a tumorigenic liver; they sustain cancer cells' growth and invasiveness, and their presence is correlated with a poor prognosis. Furthermore, TAM cross-talk with cells and components of the TME promotes immunosuppression, a desmoplastic response, and angiogenesis. In this review, we summarize the latest advances in understanding TAM heterogeneity and function, with a particular focus on TAM modulation of the TME. We also discuss the potential of targeting macrophage subpopulations and how this is now being exploited in current clinical trials for the treatment of liver cancer.

EPI-X4, a CXCR4 antagonist inhibits tumor growth in pancreatic cancer and lymphoma models

Endogenous peptide inhibitor for CXCR4 (EPI-X4) is a CXCR4 antagonist with potential for cancer therapy. It is a processed fragment of serum albumin from the hemofiltrate of dialysis patients. This study reports the efficacy of fifteen EPI-X4 derivatives in pancreatic cancer and lymphoma models. In vitro, the peptides were investigated for antiproliferation (cytotoxicity) by MTT assay. The mRNA expression for CXCR4 and CXCL12 was determined by RT-PCR, chip array and RNA sequencing. Chip array analysis yielded 634 genes associated with CXCR4/CXCL12 signaling. About 21% of these genes correlated with metastasis in the context of cell motility, proliferation, and survival. Expression levels of these genes were altered in pancreatic cancer (36%), lymphoma models (53%) and in patients' data (58%). EPI-X4 derivatives failed to inhibit cell proliferation due to low expression of CXCR4 in vitro, but inhibited tumor growth in the bioassays with significant efficacy. In the pancreatic cancer model, EPI-X4a, f and k inhibited mean tumor growth by > 50% and even caused complete remissions. In the lymphoma model, EPI-X4b, n and p inhibited mean tumor growth by > 70% and caused stable disease. Given the non-toxic and non-immunogenic properties of EPI-X4, these findings underscore its status as a promising therapy of pancreatic cancer and lymphoma and warrant further studies. SIMPLE SUMMARY: This study examined the value of chemokine receptor CXCR4 as an antineoplastic target for the endogenous peptide inhibitor of CXCR4 (EPI-X4), a 12-meric peptide derived from serum albumin. EPI-X4 inhibits CXCR4 interaction with its natural ligand, CXCL12 (SDF1). Therefore, malignancies (including pancreatic cancer and lymphoma) that depend on the CXCR4/CXCL12 pathway for progression can be targeted with EPI-X4. Of 634 genes that were linked to the CXCR4/CXCL12 pathway, 21% were associated with metastasis. In cultured human Suit2-007 pancreatic cancer cells, CXCR4 showed low to undetectable expression, which was why EPI-X4 did not inhibit pancreatic cancer cell proliferation. These findings were different in vivo, where CXCR4 was highly expressed and EPI-X4 inhibited tumor growth in rodents harboring pancreatic cancer or lymphoma. In the pancreatic cancer model, EPI-X4 derivatives a, f and k caused complete remissions, while in lymphomas EPI-X4 derivatives b, n and p caused stable disease.

Overcoming Resistance to Immune Checkpoint Blockade in Liver Cancer with Combination Therapy: Stronger Together?

Primary liver cancer, represented mainly by hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (CCA), is one of the most common and deadliest tumors worldwide. While surgical resection or liver transplantation are the best option in early disease stages, these tumors often present in advanced stages and systemic treatment is required to improve survival time. The emergence of immune checkpoint inhibitor (ICI) therapy has had a positive impact especially on the treatment of advanced cancers, thereby establishing immunotherapy as part of first-line treatment in HCC and CCA. Nevertheless, low response rates reflect on the usually cold or immunosuppressed tumor microenvironment of primary liver cancer. In this review, we aim to summarize mechanisms of resistance leading to tumor immune escape with a special focus on the composition of tumor microenvironment in both HCC and CCA, also reflecting on recent important developments in ICI combination therapy. Furthermore, we discuss how combination of ICIs with established primary liver cancer treatments (e.g. multikinase inhibitors and chemotherapy) as well as more complex combinations with state-of-the-art therapeutic concepts may reshape the tumor microenvironment, leading to higher response rates and long-lasting antitumor immunity for primary liver cancer patients.

Exploiting the immune system in hepatic tumor targeting: Unleashing the potential of drugs, natural products, and nanoparticles

Hepatic tumors present a formidable challenge in cancer therapeutics, necessitating the exploration of novel treatment strategies. In recent years, targeting the immune system has attracted interest to augment existing therapeutic efficacy. The immune system in hepatic tumors includes numerous cells with diverse actions. CD8+ T lymphocytes, T helper 1 (Th1) CD4+ T lymphocytes, alternative M1 macrophages, and natural killer (NK) cells provide the antitumor immunity. However, Foxp3+ regulatory CD4+ T cells (Tregs), M2-like tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs) are the key immune inhibitor cells. Tumor stroma can also affect these interactions. Targeting these cells and their secreted molecules is intriguing for eliminating malignant cells. The current review provides a synopsis of the immune system components involved in hepatic tumor expansion and highlights the molecular and cellular pathways that can be targeted for therapeutic intervention. It also overviews the diverse range of drugs, natural products, immunotherapy drugs, and nanoparticles that have been investigated to manipulate immune responses and bolster antitumor immunity. The review also addresses the potential advantages and challenges associated with these approaches.

Hepatocellular carcinoma (HCC) tumor microenvironment is more suppressive than colorectal cancer liver metastasis (CRLM) tumor microenvironment

BACKGROUND AND PURPOSE

While HCC is an inflammation-associated cancer, CRLM develops on permissive healthy liver microenvironment. To evaluate the immune aspects of these two different environments, peripheral blood-(PB), peritumoral-(PT) and tumoral tissues-(TT) from HCC and CRLM patients were evaluated.

METHODS

40 HCC and 34 CRLM were enrolled and freshly TT, PT and PB were collected at the surgery. PB-, PT- and TT-derived CD4+CD25+ Tregs, M/PMN-MDSC and PB-derived CD4+CD25- T-effector cells (Teffs) were isolated and characterized. Tregs' function was also evaluated in the presence of the CXCR4 inhibitor, peptide-R29, AMD3100 or anti-PD1. RNA was extracted from PB/PT/TT tissues and tested for FOXP3, CXCL12, CXCR4, CCL5, IL-15, CXCL5, Arg-1, N-cad, Vim, CXCL8, TGFβ and VEGF-A expression.

RESULTS

In HCC/CRLM-PB, higher number of functional Tregs, CD4+CD25hiFOXP3+ was detected, although PB-HCC Tregs exert a more suppressive function as compared to CRLM Tregs. In HCC/CRLM-TT, Tregs were highly represented with activated/ENTPD-1+Tregs prevalent in HCC. As compared to CRLM, HCC overexpressed CXCR4 and N-cadherin/vimentin in a contest rich in arginase and CCL5. Monocytic MDSCs were highly represented in HCC/CRLM, while high polymorphonuclear MDSCs were detected only in HCC. Interestingly, the function of CXCR4-PB-Tregs was impaired in HCC/CRLM by the CXCR4 inhibitor R29.

CONCLUSION

In HCC and CRLM, peripheral blood, peritumoral and tumoral tissues Tregs are highly represented and functional. Nevertheless, HCC displays a more immunosuppressive TME due to Tregs, MDSCs, intrinsic tumor features (CXCR4, CCL5, arginase) and the contest in which it develops. As CXCR4 is overexpressed in HCC/CRLM tumor/TME cells, CXCR4 inhibitors may be considered for double hit therapy in liver cancer patients.

The Combination of Anti-CD47 Antibody with CTLA4 Blockade Enhances Anti-Tumor Immunity in Non-Small Cell Lung Cancer via Normalization of Tumor Vasculature and Reprogramming of the Immune Microenvironment

In solid tumors, the formidable anti-tumor impact resulting from blocking the "don't eat me" signal, arising from CD47-SIRPα interaction, is constrained, especially compared to its efficacy in hematopoietic malignancies. Activating macrophage anti-tumor activity not only necessitates the inhibition of the "don't eat me" signal, but also the activation of the "eat me" (pre-phagocyte) signal. Intriguingly, the cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) antibody (Ab) has been identified to stimulate Fc receptor-mediated active phagocytes in the tumor microenvironment, thereby generating "eat me" signals. This study postulates that concurrently targeting CD47 and CTLA4 could intensify the anti-tumor effects by simultaneously blocking the "don't eat me" signal while triggering the "eat me" signal. The experimental data from this investigation confirm that the combined targeting of CD47 and CTLA4 enhances immunity against solid tumors in LLC cell-transplanted tumor-bearing mice. This effect is achieved by reducing myeloid-derived suppressor cell infiltration while increasing the presence of effector memory CD8+ T cells, NK1.1+ CD8+ T cells, and activated natural killer T cells. Meanwhile, combination therapy also alleviated anemia. Mechanistically, the anti-CD47 Ab is shown to upregulate CTLA4 levels in NSCLC cells by regulating Foxp1. Furthermore, targeting CD47 is demonstrated to promote tumor vascular normalization through the heightened infiltration of CD4+ T cells. These findings suggest that the dual targeting of CD47 and CTLA4 exerts anti-tumor effects by orchestrating the "eat me" and "don't eat me" signals, reshaping the immune microenvironment, and fostering tumor vascular normalization. This combined therapeutic approach emerges as a potent strategy for effectively treating solid tumors.

Biomarkers and prognostic factors of PD-1/PD-L1 inhibitor-based therapy in patients with advanced hepatocellular carcinoma

Systemic therapies using programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors have demonstrated commendable efficacy in some patients with advanced hepatocellular carcinoma (HCC); however, other individuals do not respond favorably. Hence, identifying the biomarkers, the prognostic factors, and their underlying mechanisms is crucial. In this review, we summarized the latest advancements in this field. Within the tumor microenvironment, PD-L1 expression is commonly utilized to predict response. Moreover, the characteristics of tumor-infiltrating lymphocytes are associated with the effectiveness of immunotherapy. Preclinical studies have identified stimulatory dendritic cells, conventional dendritic cells, and macrophages as potential biomarkers. The emergence of single-cell sequencing and spatial transcriptomics has provided invaluable insights into tumor heterogeneity through the lens of single-cell profiling and spatial distribution. With the widespread adoption of next-generation sequencing, certain genomic characteristics, including tumor mutational burden, copy number alterations, specific genes (TP53, CTNNB1, and GZMB), and signaling pathways (WNT/β-catenin) have been found to correlate with prognosis. Furthermore, clinical features such as tumor size, number, and metastasis status have demonstrated prognostic value. Notably, common indicators such as the Child-Pugh score and Eastern Cooperative Oncology Group score, which are used in patients with liver diseases, have shown potential. Similarly, commonly employed laboratory parameters such as baseline transforming growth factor beta, lactate dehydrogenase, dynamic changes in alpha-fetoprotein (AFP) and abnormal prothrombin, CRAFITY score (composed of C-reactive protein and AFP), and immune adverse events have been identified as predictive biomarkers. Novel imaging techniques such as EOB-MRI and PET/CT employing innovative tracers also have potential. Moreover, liquid biopsy has gained widespread use in biomarker studies owing to its non-invasive, convenient, and highly reproducible nature, as well as its dynamic monitoring capabilities. Research on the gut microbiome, including its composition, dynamic changes, and metabolomic analysis, has gained considerable attention. Efficient biomarker discovery relies on continuous updating of treatment strategies. Next, we summarized recent advancements in clinical research on HCC immunotherapy and provided an overview of ongoing clinical trials for contributing to the understanding and improvement of HCC immunotherapy.

Macrophage heterogeneity and its interactions with stromal cells in tumour microenvironment

Macrophages and tumour stroma cells account for the main cellular components in the tumour microenvironment (TME). Current advancements in single-cell analysis have revolutionized our understanding of macrophage diversity and macrophage-stroma interactions. Accordingly, this review describes new insight into tumour-associated macrophage (TAM) heterogeneity in terms of tumour type, phenotype, metabolism, and spatial distribution and presents the association between these factors and TAM functional states. Meanwhile, we focus on the immunomodulatory feature of TAMs and highlight the tumour-promoting effect of macrophage-tumour stroma interactions in the immunosuppressive TME. Finally, we summarize recent studies investigating macrophage-targeted therapy and discuss their therapeutic potential in improving immunotherapy by alleviating immunosuppression.

Metabolic reprogramming in the tumor microenvironment of liver cancer

The liver is essential for metabolic homeostasis. The onset of liver cancer is often accompanied by dysregulated liver function, leading to metabolic rearrangements. Overwhelming evidence has illustrated that dysregulated cellular metabolism can, in turn, promote anabolic growth and tumor propagation in a hostile microenvironment. In addition to supporting continuous tumor growth and survival, disrupted metabolic process also creates obstacles for the anticancer immune response and restrains durable clinical remission following immunotherapy. In this review, we elucidate the metabolic communication between liver cancer cells and their surrounding immune cells and discuss how metabolic reprogramming of liver cancer impacts the immune microenvironment and the efficacy of anticancer immunotherapy. We also describe the crucial role of the gut-liver axis in remodeling the metabolic crosstalk of immune surveillance and escape, highlighting novel therapeutic opportunities.

TET2-mediated tumor cGAS triggers endothelial STING activation to regulate vasculature remodeling and anti-tumor immunity in liver cancer

Induction of tumor vascular normalization is a crucial measure to enhance immunotherapy efficacy. cGAS-STING pathway is vital for anti-tumor immunity, but its role in tumor vasculature is unclear. Herein, using preclinical liver cancer models in Cgas/Sting-deficient male mice, we report that the interdependence between tumor cGAS and host STING mediates vascular normalization and anti-tumor immune response. Mechanistically, TET2 mediated IL-2/STAT5A signaling epigenetically upregulates tumor cGAS expression and produces cGAMP. Subsequently, cGAMP is transported via LRRC8C channels to activate STING in endothelial cells, enhancing recruitment and transendothelial migration of lymphocytes. In vivo studies in male mice also reveal that administration of vitamin C, a promising anti-cancer agent, stimulates TET2 activity, induces tumor vascular normalization and enhances the efficacy of anti-PD-L1 therapy alone or in combination with IL-2. Our findings elucidate a crosstalk between tumor and vascular endothelial cells in the tumor immune microenvironment, providing strategies to enhance the efficacy of combinational immunotherapy for liver cancer.

Adverse reactions of immune checkpoint inhibitors combined with angiogenesis inhibitors: A pharmacovigilance analysis of drug-drug interactions

The combination of immune checkpoint inhibitors (ICIs) and angiogenesis inhibitors (AGIs) is widely used in cancer treatment; however, drug-drug reactions (DDIs) remain unknown. We aimed to identify interaction signals for the concomitant use of ICIs and AGIs. Data were obtained from the US FDA Adverse Event Reporting System (FAERS) from January 1, 2015, to December 31, 2023. Disproportionality analysis was used for data mining by calculating the reporting odds ratio (ROR) and 95% confidence interval (95% CI). Adjusted RORs were analysed using logistic regression analysis, considering age, sex and reporting year. Further confirmation was assessed via additive and multiplicative models. We identified 75,936 reports on ICIs combined with AGIs. Significant interaction signals were observed for hepatobiliary disorders (RORcrude: 5.25, 95% CI: 5.07-5.44, RORadj: 5.01, 95% CI: 4.82-5.22, additive models: 0.2323), investigations (RORcrude: 1.66, 95% CI: 1.62-1.70, RORadj: 1.63, 95% CI: 1.58-1.67, additive models: 0.2187, multiplicative models: 1.1265), renal and urinary disorders (RORcrude: 1.87, 95% CI: 1.80-1.95, RORadj: 1.72, 95% CI: 1.64-1.79, additive models: 0.3239, multiplicative models: 1.1799) and vascular disorders (RORcrude: 1.94, 95% CI: 1.87-2.02, RORadj: 1.87, 95% CI: 1.80-1.95, additive models: 0.5823, multiplicative models: 1.5676). Subset data analysis showed positive interaction signals for PDL-1/CTLA-4 inhibitors + AGI in hepatobiliary disorders, PD-1 inhibitors + AGI in investigations, or PD-1/PDL-1 inhibitors + AGI in renal and urinary/ vascular disorders. Based on FAERS data, four systemic disorders were identified as having DDIs related to the combined use of ICIs and AGIs. Pre-clinical trials are required to explore the mechanisms underlying these interactions.

How chemokines organize the tumour microenvironment

For our immune system to contain or eliminate malignant solid tumours, both myeloid and lymphoid haematopoietic cells must not only extravasate from the bloodstream into the tumour tissue but also further migrate to various specialized niches of the tumour microenvironment to functionally interact with each other, with non-haematopoietic stromal cells and, ultimately, with cancer cells. These interactions regulate local immune cell survival, proliferative expansion, differentiation and their execution of pro-tumour or antitumour effector functions, which collectively determine the outcome of spontaneous or therapeutically induced antitumour immune responses. None of these interactions occur randomly but are orchestrated and critically depend on migratory guidance cues provided by chemokines, a large family of chemotactic cytokines, and their receptors. Understanding the functional organization of the tumour immune microenvironment inevitably requires knowledge of the multifaceted roles of chemokines in the recruitment and positioning of its cellular constituents. Gaining such knowledge will not only generate new insights into the mechanisms underlying antitumour immunity or immune tolerance but also inform the development of biomarkers (or 'biopatterns') based on spatial tumour tissue analyses, as well as novel strategies to therapeutically engineer immune responses in patients with cancer. Here we will discuss recent observations on the role of chemokines in the tumour microenvironment in the context of our knowledge of their physiological functions in development, homeostasis and antimicrobial responses.

Targeting the Heterogeneous Tumour-Associated Macrophages in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a prevalent and aggressive cancer that comprises a complex tumour microenvironment (TME). Tumour-associated macrophages (TAMs) are one of the most abundant immune cells present in the TME, and play a key role both in the development and in the progression of HCC. Thus, TAM-based immunotherapy has been presented as a promising strategy to complement the currently available therapies for HCC treatment. Among the novel approaches focusing on TAMs, reprogramming their functional state has emerged as a promising option for targeting TAMs as an immunotherapy in combination with the currently available treatment options. Nevertheless, a further understanding of the immunobiology of TAMs is still required. This review synthesizes current insights into the heterogeneous nature of TAMs in HCC and describes the mechanisms behind their pro-tumoural polarization focusing the attention on their interaction with HCC cells. Furthermore, this review underscores the potential involvement of TAMs' reprogramming in HCC therapy and highlights the urgency of advancing our understanding of these cells within the dynamic landscape of HCC.

Define cancer-associated fibroblasts (CAFs) in the tumor microenvironment: new opportunities in cancer immunotherapy and advances in clinical trials

Despite centuries since the discovery and study of cancer, cancer is still a lethal and intractable health issue worldwide. Cancer-associated fibroblasts (CAFs) have gained much attention as a pivotal component of the tumor microenvironment. The versatility and sophisticated mechanisms of CAFs in facilitating cancer progression have been elucidated extensively, including promoting cancer angiogenesis and metastasis, inducing drug resistance, reshaping the extracellular matrix, and developing an immunosuppressive microenvironment. Owing to their robust tumor-promoting function, CAFs are considered a promising target for oncotherapy. However, CAFs are a highly heterogeneous group of cells. Some subpopulations exert an inhibitory role in tumor growth, which implies that CAF-targeting approaches must be more precise and individualized. This review comprehensively summarize the origin, phenotypical, and functional heterogeneity of CAFs. More importantly, we underscore advances in strategies and clinical trials to target CAF in various cancers, and we also summarize progressions of CAF in cancer immunotherapy.