Targeting tumor-infiltrating Ly6G+ myeloid cells improves sorafenib efficacy in mouse orthotopic hepatocellular carcinoma

In-situ-formed immunotherapeutic and hemostatic dual drug-loaded nanohydrogel for preventing postoperative recurrence of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent malignancy characterized by an exceedingly high recurrence rate post-surgery, significantly impairing the prognosis of HCC patients. However, a standard in-care strategy for postoperative therapy is still lacking. Although encouraging results have been obtained in a newly published clinical trial for postoperative therapy by targeting the vascular endothelial growth factor (VEGF) and programmed death ligand 1 (anti-PD-L1), its efficacy remains constrained. Combining a hemostatic hydrogel with a nanoparticle-based drug delivery system presents an opportunity to optimize the antitumor effect. Herein, we developed a nanoplatform, termed HMSN@Sor/aP@Gel, comprising a hemostatic fibrin hydrogel and functionalized hollow mesoporous silica nanoparticles (HMSNs) loaded with sorafenib and anti-PD-L1 for locally administered targeted-immunotherapy to prevent the postoperative recurrence and metastasis of HCC. The antitumor mechanism is grounded in dual inhibition of Ras/Raf/MEK/ERK (MAPK) and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathways, synergistically complemented by PD-L1 blockade. HMSN@Sor/aP@Gel facilitates dendritic cell maturation, enhances cytotoxic T-lymphocyte infiltration, promotes the polarization of tumor-associated macrophages to M1 phenotype, induces tumor immunogenic cell death, reverses immunosuppression, and establishes immune memory to counter postoperative recurrence. Animal studies corroborate that HMSN@Sor/aP@Gel-mediated targeted immunotherapy significantly impedes primary and metastatic tumor growth and establishes immune memory to prevent recurrence post-surgery. This investigation presents a promising strategy for postoperative therapy with considerable potential for clinical translation.

Siwu decoction suppress myeloid-derived suppressor cells through tumour cells necroptosis to inhibit hepatocellular carcinoma

BACKGROUND

Human hepatocellular carcinoma (HCC) acquired resistance to anti-cancer agents due to the presence of immunosuppressive tumour microenvironment (TME) established by the interaction between tumour cells and immune populations. New treatment targeting the interaction is urgently needed and clinically beneficial to patients with HCC. This study aims to explore the anti-tumour effect of a Traditional Chinese Medicine formula Siwu Decoction (SWD) and its potential mechanism.

MATERIALS AND METHODS

The chemical profile of SWD was determined by high-performance liquid chromatography coupled with mass spectrometry. In vitro and in vivo effects of SWD in regressing HCC were assessed. The role of myeloid-derived suppressor cells (MDSCs) in mediating SWD-induced HCC inhibition was determined by adoptive transfer assay. The regulation of SWD-induced interaction between HCC cells and MDSCs was also confirmed both in vitro and in vivo.

RESULTS

SWD dose-dependent inhibited the HCC growth and lung metastasis in an orthotopic growth tumour in mice, without significant toxicity and adverse side effect. SWD induced necroptosis in HCC cells, but did not directly inhibit in vitro culture of MDSCs, instead, SWD-treated HCC cell culture supernatant suppressed MDSCs by inducing its cell apoptosis. The necroptotic response of HCC cells can also suppress the MDSCs population in the TME without reducing circulating MDSCs infiltration into the tumours. Adoptive transfer of MDSCs recovered tumour growth and lung metastasis of HCC in SWD-treated mice. In HCC cells, SWD induced a necroptotic response, and blockade of necroptotic response in HCC cells recovered the MDSCs population in vitro and in vivo, and restored tumour growth and lung metastasis in SWD-treated mice. A combination of SWD improves the anti-HCC efficacy of sorafenib without inducing adverse side effects. Albiflorin, the effective compound of SWD, its anti-HCC manner has been verified to be consistent with that of SWD.

CONCLUSION

Our study observed for the first time that SWD can suppress HCC by regulating MDSCs through necroptosis of tumour cells in the TME. The main effective compound of SWD, albiflorin can be a potential adjuvant therapy in the clinical management of human HCC.

Dynamics of the neutrophil‑to‑lymphocyte ratio during lenvatinib treatment for unresectable hepatocellular carcinoma

Lenvatinib is an approved therapy for advanced hepatocellular carcinoma (HCC). Recently, immune checkpoint inhibitors have been approved as frontline chemotherapies for HCC, and the tumor immune microenvironment (TIME) has been demonstrated to significantly affect HCC treatment. The neutrophil-to-lymphocyte ratio (NLR) is associated with the TIME, and the dynamics of the NLR are associated with prognosis or treatment efficacy in various cancer types. The present study investigated the dynamics of the TIME using the NLR in 101 patients with HCC treated with lenvatinib. Immunostaining for CD8+ tumor-infiltrating lymphocytes (TILs) was also performed in 9 patients who underwent liver tumor biopsy prior to subsequent chemotherapy for progression or discontinuation due to adverse events on lenvatinib treatment. The NLR values measured at the start of treatment (SOT), after 1 month of treatment and after 3 months of treatment were 2.78±2.20, 2.61±1.86 and 2.66±2.36, respectively (P=0.733). Among the patients with no reduction in the initial dose, there was no significant difference between the NLR after 1 month (2.34±0.25) and that at the SOT (2.86±2.33) (P=0.613). In patients who achieved a complete or partial response, the NLR at the time of the best tumor response was 1.65±0.56, which was significantly lower than that at the SOT (2.05±0.78) (P=0.023). In patients who did not respond to lenvatinib, the NLR at the time of disease progression was 3.68±3.19, which was significantly higher than that at the SOT (2.78±1.79) (P=0.043). Overall, 5 out of the 6 patients who did not respond to lenvatinib had low CD8+ TIL counts at disease progression. Although the present study included a limited number of patients, the NLR was associated with the therapeutic effects of lenvatinib. These findings suggest the potential of lenvatinib as an immunomodulator.

Subsequent locoregional therapy prolongs survival in progressive hepatocellular carcinoma patients under lenvatinib treatment

BACKGROUND

Locoregional therapy and multi-kinase inhibitor agent have been the backbone of treatment for hepatocellular carcinoma (HCC) patients. However, the effect of combination or sequential use of locoregional therapy on HCC patients receiving multi-kinase inhibitor remain uncertain. Therefore, we aim to explore whether the subsequent locoregional therapy provides better survival in HCC patients under lenvatinib treatment.

METHODS

From March 2018 to April 2020, a total of 78 unresectable HCC patients receiving lenvatinib were recruited. Image response was evaluated by dynamic image using the modified RECIST criteria. Among patients with tumor progression under lenvatinib treatment, whether receiving subsequent locoregional therapy or not were documented. Overall survival between two groups and the predictors for tumor progression were also analyzed.

RESULTS

Among the 78 patients receiving lenvatinib, the median age was 67.8 years old, and 69.2 % were male. Forty-four patients (56.4 %) experienced tumor progression with time to progression 5.1 months (95 % confidence interval (CI): 4.7-6.8) months. In multivariable Cox regression analysis, albumin-bilirubin (ALBI) grade II (adjusted HR: 2.883, P = 0.0104), and treatment duration less than three months (adjusted HR: 3.801, P = 0.0014) were the independent predictive factors for tumor progression, while patients achieving objective response under lenvatinib treatment within 12 weeks was the independent protective factor for tumor progression (adjusted HR: 0.144, P = 0.0020). Among the 44 patients with tumor progression, twenty-six (59.1 %) patients received subsequent locoregional therapy after tumor progression. Comparing to those with tumor progression without locoregional treatment, patients who received subsequent locoregional therapy had significantly better survival (1st year cumulative survival rate 70 % vs 27 %, log-rank P = 0.003).

CONCLUSION

ALBI grade, treatment duration of lenvatinib, and achieving objective image response within twelve weeks were the independent predictive factors for tumor progression. Furthermore, longer overall survival was observed in tumor progression patients with subsequent locoregional therapy and with better liver preserved function.

Hepatocellular Carcinoma and the Multifaceted Relationship with Its Microenvironment: Attacking the Hepatocellular Carcinoma Defensive Fortress

Hepatocellular carcinoma is a malignant tumor that originates from hepatocytes in an inflammatory substrate due to different degrees of liver fibrosis up to cirrhosis. In recent years, there has been growing interest in the role played by the complex interrelationship between hepatocellular carcinoma and its microenvironment, capable of influencing tumourigenesis, neoplastic growth, and its progression or even inhibition. The microenvironment is made up of an intricate network of mesenchymal cells, immune system cells, extracellular matrix, and growth factors, as well as proinflammatory cytokines and translocated bacterial products coming from the intestinal microenvironment via the enterohepatic circulation. The aim of this paper is to review the role of the HCC microenvironment and describe the possible implications in the choice of the most appropriate therapeutic scheme in the prediction of tumor response or resistance to currently applied treatments and in the possible development of future therapeutic perspectives, in order to circumvent resistance and break down the tumor's defensive fort.

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.

Self-delivery photothermal-boosted-nanobike multi-overcoming immune escape by photothermal/chemical/immune synergistic therapy against HCC

Immune checkpoint inhibitors (ICIs) combined with antiangiogenic therapy have shown encouraging clinical benefits for the treatment of unresectable or metastatic hepatocellular carcinoma (HCC). Nevertheless, therapeutic efficacy and wide clinical applicability remain a challenge due to "cold" tumors' immunological characteristics. Tumor immunosuppressive microenvironment (TIME) continuously natural force for immune escape by extracellular matrix (ECM) infiltration, tumor angiogenesis, and tumor cell proliferation. Herein, we proposed a novel concept by multi-overcoming immune escape to maximize the ICIs combined with antiangiogenic therapy efficacy against HCC. A self-delivery photothermal-boosted-NanoBike (BPSP) composed of black phosphorus (BP) tandem-augmented anti-PD-L1 mAb plus sorafenib (SF) is meticulously constructed as a triple combination therapy strategy. The simplicity of BPSP's composition, with no additional ingredients added, makes it easy to prepare and presents promising marketing opportunities. (1) NIR-II-activated BPSP performs photothermal therapy (PTT) and remodels ECM by depleting collagen I, promoting deep penetration of therapeutics and immune cells. (2) PTT promotes SF release and SF exerts anti-vascular effects and down-regulates PD-L1 via RAS/RAF/ERK pathway inhibition, enhancing the efficacy of anti-PD-L1 mAb in overcoming immune evasion. (3) Anti-PD-L1 mAb block PD1/PD-L1 recognition and PTT-induced ICD initiates effector T cells and increases response rates of PD-L1 mAb. Highly-encapsulated BPSP converted 'cold' tumors into 'hot' ones, improved CTL/Treg ratio, and cured orthotopic HCC tumors in mice. Thus, multi-overcoming immune escape offers new possibilities for advancing immunotherapies, and photothermal/chemical/immune synergistic therapy shows promise in the clinical development of HCC.

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.

The role of myeloid-derived suppressor cells in liver cancer

MDSCs are immature myeloid immune cells, which accumulate in models of liver cancer to reduce effector immune cell activity, contribute to immune escape and treatment resistance. The accumulation of MDSCs suppresses the role of CTL and the killing effects of NK cells, induces the accumulation of Treg cells, and blocks the antigen presentation of DCs, thus promoting the progression of liver cancer. Recently, immunotherapy has emerged a valuable approach following chemoradiotherapy in the therapy of advanced liver cancer. A considerable increasing of researches had proved that targeting MDSCs has become one of the therapeutic targets to enhance tumor immunity. In preclinical study models, targeting MDSCs have shown encouraging results in both alone and in combination administration. In this paper, we elaborated immune microenvironment of the liver, function and regulatory mechanisms of MDSCs, and therapeutic approaches to target MDSCs. We also expect these strategies to supply new views for future immunotherapy for the treatment of liver cancer.

Target immune components to circumvent sorafenib resistance in hepatocellular carcinoma

Sorafenib, a multi-kinase inhibitor, has been approved for cancer treatment for decades, especially hepatocellular carcinoma (HCC). Although sorafenib produced substantial clinical benefits in the initial stage, a large proportion of cancer patients acquired drug resistance in subsequent treatment, which always disturbs clinical physicians. Cumulative evidence unraveled the underlying mechanism of sorafenib, but few reports focused on the role of immune subpopulations, since the immunological rationale of sorafenib resistance has not yet been defined. Here, we reviewed the immunoregulatory effects of sorafenib on the tumor microenvironment and emphasized the potential immunological mechanisms of therapeutic resistance to sorafenib. Moreover, we also summarized the clinical outcomes and ongoing trials in combination of sorafenib with immunotherapy, highlighted the immunotherapeutic strategies to improve sorafenib efficacy, and put forward several prospective questions aimed at guiding future research in overcoming sorafenib resistance in HCC.

Therapeutic targeting of tumour myeloid cells

Myeloid cells are pivotal within the immunosuppressive tumour microenvironment. The accumulation of tumour-modified myeloid cells derived from monocytes or neutrophils - termed 'myeloid-derived suppressor cells' - and tumour-associated macrophages is associated with poor outcome and resistance to treatments such as chemotherapy and immune checkpoint inhibitors. Unfortunately, there has been little success in large-scale clinical trials of myeloid cell modulators, and only a few distinct strategies have been used to target suppressive myeloid cells clinically so far. Preclinical and translational studies have now elucidated specific functions for different myeloid cell subpopulations within the tumour microenvironment, revealing context-specific roles of different myeloid cell populations in disease progression and influencing response to therapy. To improve the success of myeloid cell-targeted therapies, it will be important to target tumour types and patient subsets in which myeloid cells represent the dominant driver of therapy resistance, as well as to determine the most efficacious treatment regimens and combination partners. This Review discusses what we can learn from work with the first generation of myeloid modulators and highlights recent developments in modelling context-specific roles for different myeloid cell subtypes, which can ultimately inform how to drive more successful clinical trials.

Midkine inhibition enhances anti-PD-1 immunotherapy in sorafenib-treated hepatocellular carcinoma via preventing immunosuppressive MDSCs infiltration

Sorafenib, a multiple-target tyrosine kinase inhibitor, is the standard of care for patients with advanced hepatocellular carcinoma (HCC), but provides limited benefits. Emerging evidences suggest that prolonged sorafenib treatment induces an immunosuppressive HCC microenvironment, but the underling mechanism is undetermined. In the present study, the potential function of midkine, a heparin-binding growth factor/cytokine, was evaluated in sorafenib-treated HCC tumors. Infiltrating immune cells of orthotopic HCC tumors were measured by flow cytometry. Differentially expressed genes in sorafenib-treated HCC tumors were evaluated by transcriptome RNA sequencing. The potential function of midkine were evaluated by western blot, T cell suppression assay, immunohistochemistry (IHC) staining and tumor xenograft model. We found that sorafenib treatment increased intratumoral hypoxia and altered HCC microenvironment towards an immune-resistant state in orthotopic HCC tumors. Sorafenib treatment promoted midkine expression and secretion by HCC cells. Moreover, forced midkine expression stimulated immunosuppressive myeloid-derived suppressor cells (MDSCs) accumulation in HCC microenvironment, while knockdown of midkine exhibited opposite effects. Furthermore, midkine overexpression promoted CD11b⁺CD33⁺HLA-DR^- MDSCs expansion from human PBMCs, while midkine depletion suppressed this effect. PD-1 blockade showed no obvious inhibition on tumor growth of sorafenib-treated HCC tumors, but the inhibitory effect was greatly enhanced by midkine knockdown. Besides, midkine overexpression promoted multiple pathways activation and IL-10 production by MDSCs. Our data elucidated a novel role of midkine in the immunosuppressive microenvironment of sorafenib-treated HCC tumors. Mikdine might be a potential target for the combination of anti-PD-1 immunotherapy in HCC patients.

Immunosuppressive tumor microenvironment modulation by chemotherapies and targeted therapies to enhance immunotherapy effectiveness

With the rapid clinical development of immune checkpoint inhibitors (ICIs), the standard of care in cancer management has evolved rapidly. However, immunotherapy is not currently beneficial for all patients. In addition to intrinsic tumor factors, other etiologies of resistance to ICIs arise from the complex interplay between cancer and its microenvironment. Recognition of the essential role of the tumor microenvironment (TME) in cancer progression has led to a shift from a tumor-cell-centered view of cancer development, to the concept of a complex tumor ecosystem that supports tumor growth and metastatic dissemination. The expansion of immunosuppressive cells represents a cardinal strategy deployed by tumor cells to escape detection and elimination by the immune system. Regulatory T lymphocytes (Treg), myeloid-derived suppressor cells (MDSCs), and type-2 tumor-associated macrophages (TAM2) are major components of these inhibitory cellular networks, with the ability to suppress innate and adaptive anticancer immunity. They therefore represent major impediments to anticancer therapies, particularly immune-based interventions. Recent work has provided evidence that, beyond their direct cytotoxic effects on cancer cells, several conventional chemotherapeutic (CT) drugs and agents used in targeted therapies (TT) can promote the elimination or inactivation of suppressive immune cells, resulting in enhanced antitumor immunity. In this review, we will analyze findings pertaining to this concept, discuss the possible molecular bases underlying the selective targeting of these immunosuppressive cells by antineoplastic agents (CT and/or TT), and consider current challenges and future prospects related to the integration of these molecules into more efficient anticancer strategies, in the era of immunotherapy.

Research Progress on the Microenvironment and Immunotherapy of Advanced Non-Small Cell Lung Cancer With Liver Metastases

Lung cancer is a malignant tumor with the highest morbidity and mortality, and more than 75% of patients are diagnosed at an advanced stage. Liver metastases occur in 20% of non-small cell lung cancer patients, and their prognosis are poor. In recent years, immune checkpoint inhibitor monotherapy and combination therapy have made breakthrough progress in advanced Non-small cell lung cancer (NSCLC) patients. However, compared with the overall population, the liver metastases population was an independent prognostic factor for poor immunotherapy response. Whether and how immunotherapy can work in NSCLC patients with liver metastases is a major and unresolved challenge. Although more and more data have been disclosed, the research progress of NSCLC liver metastasis is still limited. How liver metastasis modulates systemic antitumor immunity and the drug resistance mechanisms of the liver immune microenvironment have not been elucidated. We systematically focused on non-small cell lung cancer patients with liver metastases, reviewed and summarized their pathophysiological mechanisms, immune microenvironment characteristics, and optimization of immunotherapy strategies.

Myeloid-derived suppressor cells promote tumor growth and sorafenib resistance by inducing FGF1 upregulation and fibrosis

Background

Methods

Results

Conclusions

Neutrophils as potential therapeutic targets in hepatocellular carcinoma

The success of atezolizumab plus bevacizumab treatment contributed to a shift in systemic therapies for hepatocellular carcinoma (HCC) towards combinations that include cancer immunotherapeutic agents. Thus far, the principal focus of cancer immunotherapy has been on interrupting immune checkpoints that suppress antitumour lymphocytes. As well as lymphocytes, the HCC environment includes numerous other immune cell types, among which neutrophils are emerging as an important contributor to the pathogenesis of HCC. A growing body of evidence supports neutrophils as key mediators of the immunosuppressive environment in which some cancers develop, as well as drivers of tumour progression. If neutrophils have a similar role in HCC, approaches that target or manipulate neutrophils might have therapeutic benefits, potentially including sensitization of tumours to conventional immunotherapy. Several neutrophil-directed therapies for patients with HCC (and other cancers) are now entering clinical trials. This Review outlines the evidence in support of neutrophils as drivers of HCC and details their mechanistic roles in development, progression and metastasis, highlighting the reasons that neutrophils are well worth investigating despite the challenges associated with studying them. Neutrophil-modulating anticancer therapies entering clinical trials are also summarized.

Therapeutic efficacy of lenvatinib for hepatocellular carcinoma with iso‑high intensity in the hepatobiliary phase of Gd‑EOB‑DTPA‑MRI

Previous studies have reported that hepatocellular carcinoma (HCC) harboring WNT/β-catenin mutations exhibits iso-high intensity by gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI, i.e. EOB-MRI) during the hepatobiliary phase (HBP), thus indicating that EOB-MRI may help clinicians identify an immune exclusion class, which might not respond to treatment with immune checkpoint inhibitors. The present study analyzed the efficacy of lenvatinib for HCC with iso-high intensity during the HBP of EOB-MRI. Overall, 52 patients who underwent EOB-MRI for 140 HCC nodules were classified into iso-high-intensity and low-intensity groups during the HBP of EOB-MRI. The clinical and histological characteristics, and different responses to treatment of both groups were analyzed. The expression levels of β-catenin and glutamine synthetase, indicative of WNT/β-catenin mutations, were enhanced in the HCC with iso-high-intensity group. Nine patients had iso-high intensity, whereas 43 patients had low intensity. Tumor size was larger, and the levels of antagonist-II or vitamin K absence were higher in the iso-high-intensity group. Furthermore, 3/9 patients in the iso-high-intensity group had objective responses compared with 13/43 patients in the low-intensity group. Disease control was observed in 5/9 patients in the iso-high-intensity group and 26/43 patients in the low-intensity group. Median overall survival was 29.8 months for the iso-high-intensity group compared with 20.8 months for the low-intensity group. In the iso-high-intensity group, the median progression-free survival rate was 6.7 months compared with 5.6 months in the low-intensity group. No differences in best percentage change from baseline tumor size were observed in either group. Although few patients were included in this study, the present findings suggested that the efficacy of lenvatinib was unaffected by signal intensity during the HBP of EOB-MRI.

Targeting Immune Cells in the Tumor Microenvironment of HCC: New Opportunities and Challenges

Immune associated cells in the microenvironment have a significant impact on the development and progression of hepatocellular carcinoma (HCC) and have received more and more attention. Different types of immune-associated cells play different roles, including promoting/inhibiting HCC and several different types that are controversial. It is well known that immune escape of HCC has become a difficult problem in tumor therapy. Therefore, in recent years, a large number of studies have focused on the immune microenvironment of HCC, explored many mechanisms worth identifying tumor immunosuppression, and developed a variety of immunotherapy methods as targets, laying the foundation for the final victory in the fight against HCC. This paper reviews recent studies on the immune microenvironment of HCC that are more reliable and important, and provides a more comprehensive view of the investigation of the immune microenvironment of HCC and the development of more immunotherapeutic approaches based on the relevant summaries of different immune cells.

Kinase Inhibitors' Effects on Innate Immunity in Solid Cancers

Simple Summary

In this review, we evaluate the updated data of the immunological effects of kinase inhibitors on the innate immune system and provide an in-depth analysis of the underlying mechanisms. We also discuss how this immunological effect can be harnessed to improve cancer treatment and highlight recent successes, such as the combination with anti-tumor immunotherapy. Last, we explore novel kinase targets and the incorporation of them with targeted drug delivery techniques as promising research areas.

Abstract

Innate immune cells constitute a plastic and heterogeneous cell population of the tumor microenvironment. Because of their high tumor infiltration and close interaction with resident tumor cells, they are compelling targets for anti-cancer therapy through either ablation or functionally reprogramming. Kinase inhibitors (KIs) that target aberrant signaling pathways in tumor proliferation and angiogenesis have been shown to have additional immunological effects on myeloid cells that may contribute to a protective antitumor immune response. However, in patients with malignancies, these effects are poorly described, warranting meticulous research to identify KIs’ optimal immunomodulatory effect to support developing targeted and more effective immunotherapy. As many of these KIs are currently in clinical trials awaiting approval for the treatment of several types of solid cancer, we evaluate here the information on this drug class’s immunological effects and how such mechanisms can be harnessed to improve combined treatment regimens in cancer.

RNA Activation-A Novel Approach to Therapeutically Upregulate Gene Transcription

RNA activation (RNAa) is a mechanism whereby RNA oligos complementary to genomic sequences around the promoter region of genes increase the transcription output of their target gene. Small activating RNA (saRNA) mediate RNAa through interaction with protein co-factors to facilitate RNA polymerase II activity and nucleosome remodeling. As saRNA are small, versatile and safe, they represent a new class of therapeutics that can rescue the downregulation of critical genes in disease settings. This review highlights our current understanding of saRNA biology and describes various examples of how saRNA are successfully used to treat various oncological, neurological and monogenic diseases. MTL-CEBPA, a first-in-class compound that reverses CEBPA downregulation in oncogenic processes using CEBPA-51 saRNA has entered clinical trial for the treatment of hepatocellular carcinoma (HCC). Preclinical models demonstrate that MTL-CEBPA reverses the immunosuppressive effects of myeloid cells and allows for the synergistic enhancement of other anticancer drugs. Encouraging results led to the initiation of a clinical trial combining MTL-CEBPA with a PD-1 inhibitor for treatment of solid tumors.

Therapeutic Values of Myeloid-Derived Suppressor Cells in Hepatocellular Carcinoma: Facts and Hopes

Simple Summary

Myeloid-derived suppressor cells restrict the effectiveness of immune-checkpoint inhibitors for a subset of patients mainly through thwarting T cell infiltration into tumor sites. Treatments targeting MDSCs have shown potent inhibitory effects on multiple tumors, including hepatocellular carcinoma. In this review, we summarize the pathological mechanisms of MDSCs and their clinical significance as prognostic and predictive biomarkers for HCC patients, and we provide the latest progress of MDSCs-targeting treatment in HCC.

Abstract

One of the major challenges in hepatocellular carcinoma (HCC) treatment is drug resistance and low responsiveness to systemic therapies, partly due to insufficient T cell infiltration. Myeloid-derived suppressor cells (MDSCs) are immature marrow-derived cell populations with heterogeneity and immunosuppression characteristics and are essential components of the suppressive tumor immune microenvironment (TIME). Increasing evidence has demonstrated that MDSCs are indispensable contributing factors to HCC development in a T cell-dependent or non-dependent manner. Clinically, the frequency of MDSCs is firmly linked to HCC clinical outcomes and the effectiveness of immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs). Furthermore, MDSCs can also be used as prognostic and predictive biomarkers for patients with HCC. Therefore, treatments reprograming MDSCs may offer potential therapeutic opportunities in HCC. Here, we recapitulated the dynamic relevance of MDSCs in the initiation and development of HCC and paid special attention to the effect of MDSCs on T cells infiltration in HCC. Finally, we pointed out the potential therapeutic effect of targeting MDSCs alone or in combination, hoping to provide new insights into HCC treatment.

Distinct mechanisms govern populations of myeloid-derived suppressor cells in chronic viral infection and cancer

Myeloid-derived suppressor cells (MDSCs) are major negative regulators of immune responses in cancer and chronic infections. It remains unclear if regulation of MDSC activity in different conditions is controlled by similar mechanisms. We compared MDSCs in mice with cancer and lymphocytic choriomeningitis virus (LCMV) infection. Chronic LCMV infection caused the development of monocytic MDSCs (M-MDSCs) but did not induce polymorphonuclear MDSCs (PMN-MDSCs). In contrast, both MDSC populations were present in cancer models. An acquisition of immune-suppressive activity by PMN-MDSCs in cancer was controlled by IRE1α and ATF6 pathways of the endoplasmic reticulum (ER) stress response. Abrogation of PMN-MDSC activity by blockade of the ER stress response resulted in an increase in tumor-specific immune response and reduced tumor progression. In contrast, the ER stress response was dispensable for suppressive activity of M-MDSCs in cancer and LCMV infection. Acquisition of immune-suppressive activity by M-MDSCs in spleens was mediated by IFN-γ signaling. However, it was dispensable for suppressive activity of M-MDSCs in tumor tissues. Suppressive activity of M-MDSCs in tumors was retained due to the effect of IL-6 present at high concentrations in the tumor site. These results demonstrate disease- and population-specific mechanisms of MDSC accumulation and the need for targeting different pathways to achieve inactivation of these cells.

Angiogenesis and immune checkpoint dual blockade in combination with radiotherapy for treatment of solid cancers: opportunities and challenges

Several immune checkpoint blockades (ICBs) capable of overcoming the immunosuppressive roles of the tumor immune microenvironment have been approved by the US Food and Drug Administration as front-line treatments of various tumor types. However, due to the considerable heterogeneity of solid tumor cells, inhibiting one target will only influence a portion of the tumor cells. One way to enhance the tumor-killing efficiency is to develop a multiagent therapeutic strategy targeting different aspects of tumor biology and the microenvironment to provide the maximal clinical benefit for patients with late-stage disease. One such strategy is the administration of anti-PD1, an ICB, in combination with the humanized monoclonal antibody bevacizumab, an anti-angiogenic therapy, to patients with recurrent/metastatic malignancies, including hepatocellular carcinoma, metastatic renal cell carcinoma, non-small cell lung cancer, and uterine cancer. Radiotherapy (RT), a critical component of solid cancer management, has the capacity to prime the immune system for an adaptive antitumor response. Here, we present an overview of the most recent published data in preclinical and clinical studies elucidating that RT could further potentiate the antitumor effects of immune checkpoint and angiogenesis dual blockade. In addition, we explore opportunities of triple combinational treatment, as well as discuss the challenges of validating biomarkers and the management of associated toxicity.

Effectiveness of Transarterial Chemoembolization-First Treatment for Advanced Hepatocellular Carcinoma: A Propensity Score Matching Analysis

Background

Still in real-world practice, advanced hepatocellular carcinoma (HCC) patients are treated with transarterial chemoembolization (TACE). This study compared the therapeutic effectiveness of initial TACE treatment and initial sorafenib treatment in advanced HCC patients.

Patient and Methods

Advanced HCC patients initially treated with sorafenib or TACE were included in this study. Treatment crossover due to an unfavorable response to initial treatment was allowed. Propensity score (PS) matching was applied for balancing baseline characteristics. The primary outcome was overall survival (OS) and the secondary outcomes included tumor response.

Results

A total of 554 patients were included in this study: 85 were initially treated with sorafenib (the sorafenib-first group) and 469 with TACE (the TACE-first group). In the entire cohort, the TACE-first group was associated with lower risk of death [adjusted hazard ratio (HR)=0.75, P=0.04]. In the PS-matched cohort (85 patients per group), the TACE-first group showed longer OS than the sorafenib-first group in both univariable (HR=0.68, P=0.02) and multivariable analyses (adjusted HR=0.58, P=0.002). Specifically, within both the entire and the PS-matched cohorts, the TACE-first group showed longer OS in subgroups with major portal vein tumor thrombosis (HR=0.72, P=0.048; HR=0.52, P=0.003) or infiltrative HCC (HR=0.42, P<0.001; HR=0.30, P=0.004, respectively). The objective response rate was higher in the TACE-first group (29.3% vs 14.7%, P=0.03) within the PS-matched cohort.

Conclusion

For advanced HCC, initial TACE leads to longer OS with a more favorable tumor response than initial sorafenib treatment. Intrahepatic tumor control with initial locoregional therapy may be a potent strategy for advanced HCC.

Combination of molecularly targeted therapies and immune checkpoint inhibitors in the new era of unresectable hepatocellular carcinoma treatment

Multikinase inhibitors (MKIs) have been the only first-line treatment for advanced hepatocellular carcinoma (HCC) for more than a decade, until the approval of immune checkpoint inhibitors (ICIs). Moreover, the combination regimen of atezolizumab (anti-programmed cell death protein ligand 1 antibody) plus bevacizumab (anti-vascular endothelial growth factor monoclonal antibody) has recently been demonstrated to have superior efficacy when compared with sorafenib monotherapy. The remarkable efficacy has made this combination therapy the new standard treatment for advanced HCC. In addition to MKIs, many other molecularly targeted therapies are under investigation, some of which have shown promising results. Therefore, in the era of immuno-oncology, there is a significant rationale for testing the combinations of molecularly targeted therapies and ICIs. Indeed, numerous preclinical and clinical studies have shown the synergic antitumor efficacy of such combinations. In this review, we aim to summarize the current knowledge on the combination of molecularly targeted therapies and immune checkpoint therapies for HCC from both preclinical and clinical perspectives.

Elevated M-MDSCs in Circulation Are Indicative of Poor Prognosis in Diffuse Large B-Cell Lymphoma Patients

Myeloid-derived suppressor cells (MDSCs) are defined as negative regulators that suppress the immune response through a variety of mechanisms, which usually cluster in cancer, inflammation, and autoimmune diseases. This study aims to investigate the correlation between M-MDSCs and the clinical features of diffuse large B-cell lymphoma (DLBCL) patients, as well as the possible accumulation mechanism of M-MDSCs. The level of M-MDSCs is significantly increased in newly diagnosed and relapsed DLBCL patients. Regarding newly diagnosed DLBCL patients, the frequency of M-MDSCs is positively correlated with tumor progression and negatively correlated with overall survival (OS). More importantly, the level of M-MDSCs can be defined as a biomarker for a poor prognosis in DLBCL patients. Additionally, interleukin-35 (IL-35) mediates the accumulation of M-MDSCs in DLBCL patients. Anti-IL-35 treatment significantly reduces levels of M-MDSCs in Ly8 tumor-bearing mice. Thus, M-MDSCs are involved in the pathological process of DLBCL. Targeting M-MDSCs may be a promising therapeutic strategy for the treatment of DLBCL patients.

Identification and characterization of B220+/B220- subpopulations in murine Gr1+CD11b+ cells during tumorigenesis

Although all murine MDSCs are defined as Gr1⁺CD11b⁺, their true immunophenotype remains elusive. In this study, we found murine Gr1⁺CD11b⁺ cells can be divided into two subsets: Gr1⁺CD11b⁺B220^- and Gr1⁺CD11b⁺B220⁺, especially in the spleen tissues. Unlike the dominant B220^- subset, the B220⁺ subpopulation was not induced by tumor in vivo. Moreover, Gr1⁺CD11b⁺B220⁺ cells from tumor-bearing mice spleens were unable to induce arginase 1 and inducible nitric oxide synthase expression, inhibit T cell proliferation, or promote tumor growth in primary tumor site. Nevertheless, these cells suppressed tumor metastasis in vivo and reduced cancer cell motility in vitro, while Gr1⁺CD11b⁺B220^- cells from tumor-bearing mice spleens promoted tumor metastasis and enhanced cancer cell motility. Furthermore, both the polymorphonuclear (PMN-MDSCs) and monocytic MDSCs (Mo-MDSCs) could be further divided into B220^- and B220⁺ subsets; interestingly, tumor only induced the expansion of B220^- PMN-MDSCs and B220^- Mo-MDSCs, but not the B220⁺ counterparts. Compared with B220^- PMN-MDSCs and B220^- Mo-MDSCs, the Ly6G⁺Ly6C^-CD11b⁺B220⁺ and Ly6G^-Ly6C⁺CD11b⁺B220⁺ cells from tumor-bearing mice spleens exhibited a more mature phenotype without immunosuppressive activity. Additionally, IL-6 deficiency attenuated the tumor-induced accumulation of MDSCs, B220^- MDSCs and B220^- PMN-MDSCs but increased the percentages of Gr1⁺CD11b⁺B220⁺, Ly6G⁺Ly6C^-CD11b⁺B220⁺, and Ly6G^-Ly6C⁺CD11b⁺B220⁺ cells, indicating the opposing roles of the IL-6 signaling pathway in the expansion of B220^- MDSCs and their B220⁺ counterparts. Taken together, our findings indicate that the B220⁺ subset is a distinct subset of Gr1⁺CD11b⁺ cells functionally different from the B220^- subpopulation during tumorigenesis and induction of MDSCs to B220⁺ cells may be helpful for cancer therapy.

Regorafenib enhances antitumor immunity via inhibition of p38 kinase/Creb1/Klf4 axis in tumor-associated macrophages

BACKGROUND

Regorafenib and other multikinase inhibitors may enhance antitumor efficacy of anti-program cell death-1 (anti-PD1) therapy in hepatocellular carcinoma (HCC). Its immunomodulatory effects, besides anti-angiogenesis, were not clearly defined.

METHODS

In vivo antitumor efficacy was tested in multiple syngeneic liver cancer models. Murine bone marrow-derived macrophages (BMDMs) were tested in vitro for modulation of polarization by regorafenib and activation of cocultured T cells. Markers of M1/M2 polarization were measured by quantitative reverse transcription PCR (RT-PCR), arginase activity, flow cytometry, and ELISA. Knockdown of p38 kinase and downstream Creb1/Klf4 signaling on macrophage polarization were confirmed by using knockdown of the upstream MAPK14 kinase, chemical p38 kinase inhibitor, and chromatin immunoprecipitation.

RESULTS

Regorafenib (5 mg/kg/day, corresponding to about half of human clinical dosage) inhibited tumor growth and angiogenesis in vivo similarly to DC-101 (anti-VEGFR2 antibody) but produced higher T cell activation and M1 macrophage polarization, increased the ratio of M1/M2 polarized BMDMs and proliferation/activation of cocultured T cells in vitro, indicating angiogenesis-independent immunomodulatory effects. Suppression of p38 kinase phosphorylation and downstream Creb1/Klf4 activity in BMDMs by regorafenib reversed M2 polarization. Regorafenib enhanced antitumor efficacy of adoptively transferred antigen-specific T cells. Synergistic antitumor efficacy between regorafenib and anti-PD1 was associated with multiple immune-related pathways in the tumor microenvironment.

CONCLUSION

Regorafenib may enhance antitumor immunity through modulation of macrophage polarization, independent of its anti-angiogenic effects. Optimization of regorafenib dosage for rational design of combination therapy regimen may improve the therapeutic index in the clinic.

Augmenting Anticancer Immunity Through Combined Targeting of Angiogenic and PD-1/PD-L1 Pathways: Challenges and Opportunities

Cancer immunotherapy (CIT) with antibodies targeting the programmed cell death 1 protein (PD-1)/programmed cell death 1 ligand 1 (PD-L1) axis have changed the standard of care in multiple cancers. However, durable antitumor responses have been observed in only a minority of patients, indicating the presence of other inhibitory mechanisms that act to restrain anticancer immunity. Therefore, new therapeutic strategies targeted against other immune suppressive mechanisms are needed to enhance anticancer immunity and maximize the clinical benefit of CIT in patients who are resistant to immune checkpoint inhibition. Preclinical and clinical studies have identified abnormalities in the tumor microenvironment (TME) that can negatively impact the efficacy of PD-1/PD-L1 blockade. Angiogenic factors such as vascular endothelial growth factor (VEGF) drive immunosuppression in the TME by inducing vascular abnormalities, suppressing antigen presentation and immune effector cells, or augmenting the immune suppressive activity of regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages. In turn, immunosuppressive cells can drive angiogenesis, thereby creating a vicious cycle of suppressed antitumor immunity. VEGF-mediated immune suppression in the TME and its negative impact on the efficacy of CIT provide a therapeutic rationale to combine PD-1/PD-L1 antibodies with anti-VEGF drugs in order to normalize the TME. A multitude of clinical trials have been initiated to evaluate combinations of a PD-1/PD-L1 antibody with an anti-VEGF in a variety of cancers. Recently, the positive results from five Phase III studies in non-small cell lung cancer (adenocarcinoma), renal cell carcinoma, and hepatocellular carcinoma have shown that combinations of PD-1/PD-L1 antibodies and anti-VEGF agents significantly improved clinical outcomes compared with respective standards of care. Such combinations have been approved by health authorities and are now standard treatment options for renal cell carcinoma, non-small cell lung cancer, and hepatocellular carcinoma. A plethora of other randomized studies of similar combinations are currently ongoing. Here, we discuss the principle mechanisms of VEGF-mediated immunosuppression studied in preclinical models or as part of translational clinical studies. We also discuss data from recently reported randomized clinical trials. Finally, we discuss how these concepts and approaches can be further incorporated into clinical practice to improve immunotherapy outcomes for patients with cancer.

IL-28B variant as a predictor in patients with advanced hepatocellular carcinoma treated with hepatic arterial infusion chemotherapy

BACKGROUND AND AIM

Single-nucleotide polymorphisms (SNPs) of the interleukin-28B (IL-28B) gene are associated with the effectiveness of interferon therapy for chronic hepatitis C infection. Whether the IL-28B genotype affects the course of treatment and the outcomes of patients with advanced hepatocellular carcinoma (HCC) is unknown.

METHODS

We detected the IL-28B SNP (rs8099917) using TaqMan PreDesigned SNP Genotyping Assays to assess the effects of the IL-28B genotype on treatment efficacy and prognosis of patients with advanced HCC treated with hepatic arterial infusion chemotherapy (HAIC) between September 2003 and January 2015.

RESULTS

The study included 154 patients who received HAIC to treat advanced HCC, among which 27 (17.5%) had the minor genotype, IL-28B rs8099917 TG or GG, and the others had the major genotype, IL-28B rs8099917 TT. The objective response rates of patients with the minor or major genotype were 51.9% and 29.1% (P = 0.022), respectively. Multivariate analysis revealed that the minor genotype remained associated with the response to HAIC (odds ratio, 2.620; P = 0.026). The median overall survival of patients with major or minor genotypes was 14.1 and 16.9 months, respectively, and the overall survival of patients with the major genotype was significantly shorter than that of patients with the minor genotype (P = 0.027). Multivariate analysis revealed that the major genotype was an independent, unfavorable prognostic factor (hazard ratio, 1.720; P = 0.024). Consistent results were obtained in selected populations after propensity score matching analysis.

CONCLUSIONS

The IL-28B SNP (rs8099917) will serve as a useful predictor of the outcomes of patients with advanced HCC treated with HAIC.

MTL-CEBPA, a Small Activating RNA Therapeutic Upregulating C/EBP-α, in Patients with Advanced Liver Cancer: A First-in-Human, Multicenter, Open-Label, Phase I Trial

PURPOSE

Transcription factor C/EBP-α (CCAAT/enhancer-binding protein alpha) acts as a master regulator of hepatic and myeloid functions and multiple oncogenic processes. MTL-CEBPA is a first-in-class small activating RNA oligonucleotide drug that upregulates C/EBP-α.

PATIENTS AND METHODS

We conducted a phase I, open-label, dose-escalation trial of MTL-CEBPA in adults with advanced hepatocellular carcinoma (HCC) with cirrhosis, or resulting from nonalcoholic steatohepatitis or with liver metastases. Patients received intravenous MTL-CEBPA once a week for 3 weeks followed by a rest period of 1 week per treatment cycle in the dose-escalation phase (3+3 design).

RESULTS

Thirty-eight participants have been treated across six dose levels (28-160 mg/m2) and three dosing schedules. Thirty-four patients were evaluable for safety endpoints at 28 days. MTL-CEBPA treatment-related adverse events were not associated with dose, and no maximum dose was reached across the three schedules evaluated. Grade 3 treatment-related adverse events occurred in nine (24%) patients. In 24 patients with HCC evaluable for efficacy, an objective tumor response was achieved in one patient [4%; partial response (PR) for over 2 years] and stable disease (SD) in 12 (50%). After discontinuation of MTL-CEBPA, seven patients were treated with tyrosine kinase inhibitors (TKIs); three patients had a complete response with one further PR and two with SD.

CONCLUSIONS

MTL-CEBPA is the first saRNA in clinical trials and demonstrates an acceptable safety profile and potential synergistic efficacy with TKIs in HCC. These encouraging phase I data validate targeting of C/EBP-α and have prompted MTL-CEBPA + sorafenib combination studies in HCC.

The New Era of Cancer Immunotherapy: Targeting Myeloid-Derived Suppressor Cells to Overcome Immune Evasion

Suppression of antitumor immune responses is one of the main mechanisms by which tumor cells escape from destruction by the immune system. Myeloid-derived suppressor cells (MDSCs) represent the main immunosuppressive cells present in the tumor microenvironment (TME) that sustain cancer progression. MDSCs are a heterogeneous group of immature myeloid cells with a potent activity against T-cell. Studies in mice have demonstrated that MDSCs accumulate in several types of cancer where they promote invasion, angiogenesis, and metastasis formation and inhibit antitumor immunity. In addition, different clinical studies have shown that MDSCs levels in the peripheral blood of cancer patients correlates with tumor burden, stage and with poor prognosis in multiple malignancies. Thus, MDSCs are the major obstacle to many cancer immunotherapies and their targeting may be a beneficial strategy for improvement the efficiency of immunotherapeutic interventions. However, the great heterogeneity of these cells makes their identification in human cancer very challenging. Since both the phenotype and mechanisms of action of MDSCs appear to be tumor-dependent, it is important to accurately characterized the precise MDSC subsets that have clinical relevance in each tumor environment to more efficiently target them. In this review we summarize the phenotype and the suppressive mechanisms of MDSCs populations expanded within different tumor contexts. Further, we discuss about their clinical relevance for cancer diagnosis and therapy.

New insights on sorafenib resistance in liver cancer with correlation of individualized therapy

Liver cancer is highly malignant and insensitive to cytotoxic chemotherapy and is associated with very poor patient prognosis. In 2007, the small-molecule targeted drug sorafenib was approved for the treatment of advanced liver cancer. In the subsequent ten years, sorafenib has been the only first-line therapeutic targeted drug for advanced hepatocellular carcinoma (HCC). However, a number of clinical studies show that a considerable percentage of patients with liver cancer are insensitive to sorafenib. The number of patients who actually benefit significantly from sorafenib treatment is very limited, and the overall efficacy of sorafenib is far from satisfactory, which has attracted the attention of researchers. Based on previous studies and reports, this article reviews the potential mechanisms of sorafenib resistance (SR) and summarizes the biomarkers and clinicopathological indicators that might be used for predicting sorafenib response and developing personalized therapy.

Challenges of combination therapy with immune checkpoint inhibitors for hepatocellular carcinoma

Immune checkpoint inhibitor (ICI) therapy targeting anti-programmed cell death-1 (anti-PD-1) or its ligand (anti-PD-L1) is the backbone of numerous combination regimens aimed at improving the objective response and survival of patients with hepatocellular carcinoma (HCC). Clinical trials of immuno-oncology regimens in other cancer types have shed light on issues of study design, including how to choose candidate regimens based on early-phase trial results, statistical considerations in trials with multiple primary endpoints, and the importance of predictive biomarkers. In this review, the updated data from early-phase trials of combination immunotherapy for HCC are summarised. Since the most extensively tested combination regimens for advanced HCC comprise anti-PD-1/anti-PD-L1 agents plus antiangiogenic agents, the relative benefit and antitumor mechanism of antiangiogenic multikinase inhibitors versus specific VEGF/VEGFR inhibitors are discussed. Other critical issues in the development of combination immunotherapy, including optimal management of immune-related adverse events and the value of ICI therapy in combination with locoregional treatment for HCC, are also explored.

Modulation of Immunosuppression by Oligonucleotide-Based Molecules and Small Molecules Targeting Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells that exert suppressive function on the immune response. MDSCs expand in tumor-bearing hosts or in the tumor microenvironment and suppress T cell responses via various mechanisms, whereas a reduction in their activities has been observed in autoimmune diseases or infections. It has been reported that the symptoms of various diseases, including malignant tumors, can be alleviated by targeting MDSCs. Moreover, MDSCs can contribute to patient resistance to therapy using immune checkpoint inhibitors. In line with these therapeutic approaches, diverse oligonucleotide-based molecules and small molecules have been evaluated for their therapeutic efficacy in several disease models via the modulation of MDSC activity. In the current review, MDSC-targeting oligonucleotides and small molecules are briefly summarized, and we highlight the immunomodulatory effects on MDSCs in a variety of disease models and the application of MDSC-targeting molecules for immuno-oncologic therapy.

Differential Organ-Specific Tumor Response to Immune Checkpoint Inhibitors in Hepatocellular Carcinoma

BACKGROUND AND AIMS

Immune checkpoint inhibitors (ICIs) exhibit significant clinical activity in patients with advanced hepatocellular carcinoma (HCC). This study explored whether tumor response to ICIs in HCC varies among different organs.

METHODS

We reviewed the data of patients with advanced HCC who had received ICIs. Patients with measurable diseases were enrolled. Organ-specific response criteria, adapted from RECIST 1.1 and immune-related RECIST, were used to evaluate the objective response to ICIs in tumors located in the liver, lung, lymph node, and other intra-abdominal sites.

RESULTS

Of the 75 enrolled patients with advanced HCC, 51 and 11 patients had chronic hepatitis B virus and chronic hepatitis C virus infection, respectively. Regarding ICI treatment, 58, 1, and 16 patients had undergone anti-PD-1/anti-PD-L1 monoclonal antibody (mAb) alone, anti-CTLA4 mAb alone, and anti-PD-1 mAb plus anti-CTLA4 mAb, respectively; 20 and 55 patients had received ICIs as first-line or ≥second-line therapy. The overall objective response rate (ORR) was 28.0%. In total, 58, 34, 19, and 18 patients had measurable hepatic tumors and lung, lymph node, and other intra-abdominal metastases, and the corresponding organ-specific ORRs were 22.4, 41.2, 26.3, and 38.9%, respectively. Of the 39 patients who had both hepatic and extrahepatic tumors, 12 had disease control in extrahepatic tumors while progressive disease (PD) in hepatic tumors, whereas only 4 exhibited disease control in hepatic tumors while PD in extrahepatic tumors (p = 0.046, McNemar test). Of the 16 patients with only evaluable tumors in the liver and lungs at baseline, 8 had disease control in the lungs while PD in the liver, and none experienced disease control in the liver while PD in the lungs (p = 0.005).

CONCLUSIONS

The hepatic tumors of HCC may be less responsive to ICIs than extrahepatic lesions. Lung metastases responded most favorably to ICIs. The mechanisms underlying this differential response to ICIs warrant further investigation.

Targeting Myeloid Cells in Combination Treatments for Glioma and Other Tumors

Myeloid cells constitute a significant part of the immune system in the context of cancer, exhibiting both immunostimulatory effects, through their role as antigen presenting cells, and immunosuppressive effects, through their polarization to myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages. While they are rarely sufficient to generate potent anti-tumor effects on their own, myeloid cells have the ability to interact with a variety of immune populations to aid in mounting an appropriate anti-tumor immune response. Therefore, myeloid therapies have gained momentum as a potential adjunct to current therapies such as immune checkpoint inhibitors (ICIs), dendritic cell vaccines, oncolytic viruses, and traditional chemoradiation to enhance therapeutic response. In this review, we outline critical pathways involved in the recruitment of the myeloid population to the tumor microenvironment and in their polarization to immunostimulatory or immunosuppressive phenotypes. We also emphasize existing strategies of modulating myeloid recruitment and polarization to improve anti-tumor immune responses. We then summarize current preclinical and clinical studies that highlight treatment outcomes of combining myeloid targeted therapies with other immune-based and traditional therapies. Despite promising results from reports of limited clinical trials thus far, there remain challenges in optimally harnessing the myeloid compartment as an adjunct to enhancing anti-tumor immune responses. Further large Phase II and ultimately Phase III clinical trials are needed to elucidate the treatment benefit of combination therapies in the fight against cancer.

Increased CD14+HLA-DR-/low Myeloid-Derived Suppressor Cells Correlate With Disease Severity in Systemic Lupus Erythematosus Patients in an iNOS-Dependent Manner

Myeloid-derived suppressor cells (MDSCs) comprise of a population of cells, which suppress the innate and adaptive immune system via different mechanisms. MDSCs are accumulated under pathological conditions. The present study aimed to clarify the pathological role of MDSCs in systemic lupus erythematosus (SLE) patients. Consequently, the level of circulating M-MDSCs was significantly increased in newly diagnosed SLE patients as compared to healthy controls. An elevated level of M-MDSCs was positively correlated with the disease severity in SLE patients and an immunosuppressive role was exerted in an iNOS-dependent manner. The decrease in the number of M-MDSCs after therapy rendered them as an indicator for the efficacy of treatment. These results demonstrated that M-MDSCs participated in the pathological progress in SLE patients. Thus, MDSCs are attractive biomarkers and therapeutic targets for SLE patients.

Targeting myeloid-derived suppressor cells in the treatment of hepatocellular carcinoma: current state and future perspectives

Systemic therapy for advanced hepatocellular carcinoma (HCC) has been focusing on overcoming tumor angiogenesis and immunosuppression. Myeloid-derived suppressor cells (MDSCs) promote both angiogenesis and immunosuppression in the tumor microenvironment (TME). Multiple clinical studies have demonstrated the prognostic implications of and suggested the translational significance of MDSCs in patients with HCC. In preclinical HCC models, targeting MDSCs has been shown to enhance antitumor efficacy of sorafenib or immune checkpoint inhibitors. Reversing the protumor effects of MDSCs could be achieved by depleting MDSCs, blocking MDSC trafficking and migration into TME, and inhibiting the immunosuppressive functions of MDSCs. To date, these strategies have not yet been validated to be clinically useful in patients with malignancy including HCC. Future studies should focus on identifying specific markers for human MDSCs and developing combination approaches incorporating MDSC-targeting therapy in the treatment of HCC.

Increased Expression of Programmed Death-Ligand 1 in Infiltrating Immune Cells in Hepatocellular Carcinoma Tissues after Sorafenib Treatment

OBJECTIVE

Programmed death-ligand 1 (PD-L1) expression in the tumor microenvironment (TME) has been reported to be related to prognosis in patients with hepatocellular carcinoma (HCC) after hepatectomy. The impact of sorafenib on PD-L1 expression in the TME of advanced HCC is unclear.

PATIENTS AND METHODS

Patients with HCC who received sorafenib for advanced disease at National Taiwan University Hospital, Taipei, Taiwan, and who had paired HCC tissues obtained before and after sorafenib treatment were included in the study group. HCC patients not treated with sorafenib who had paired primary and recurrent or metastatic tissues were identified as the reference group. The membrane PD-L1 staining, detected by immunohistochemistry (IHC) using SP142 antibody, was semiquantitatively scored in tumor cells (TCs) or tumor-infiltrating immune cells (ICs). Additional IHC assays were employed to characterize the PD-L1-expressing ICs.

RESULTS

Twenty-three advanced HCC patients with pre- and post-sorafenib paired HCC tissues were included in the study group. The median duration of sorafenib treatment was 4.3 months (range: 1.3-18.7). PD-L1 expression in ICs was significantly higher in post-sorafenib HCC tissues than in pre-sorafenib HCC tissues (pre-sorafenib vs. post-sorafenib IHC 0/1/2/3: 11/5/5/2 vs. 5/5/2/11, p = 0.016). However, PD-L1 expression in TCs was not significantly different between pre- and post-sorafenib tissues (IHC 0/1/2/3: 19/2/0/2 vs. 14/5/0/4, p = 0.094). In the reference group of 44 patients not treated with sorafenib, PD-L1 expression in ICs and TCs was not significantly different between the paired primary and metastatic HCC tissues. By performing IHC double staining with PD-L1 and CD68, we found the PD-L1-expressing ICs were mainly CD68-positive macrophages. PD-L1 expression levels of pre- and post-sorafenib tissues were not associated with patients' overall survival or duration of sorafenib treatment.

CONCLUSIONS

PD-L1 expression in ICs was significantly increased in post-sorafenib HCC tissues. The mechanisms and clinical significance of this observation warrants further investigation.

Changes in the frequency of myeloid-derived suppressor cells after transarterial chemoembolization with gelatin sponge microparticles for hepatocellular carcinoma

Purpose

A series of clinical studies have established the safety and efficacy of transcatheter arterial chemoembolization (TACE) with gelatin sponge microparticles (GSMs) in treating hepatocellular carcinoma (HCC). HCC can lead to obvious necrosis inside tumors, especially larger ones, although it is unclear whether such necrotic tumor tissue can induce favorable immune reactions against the tumor. Myeloid-derived suppressor cells (MDSCs) have immunosuppressive functions and are currently considered a very important cell type affecting tumor immunity. This study observed changes in MDSC frequency in peripheral blood before and after GSM–TACE to evaluate the effect on the immune function of HCC patients.

Methods

Eight patients diagnosed with HCC underwent GSM–TACE treatment in the Hepatobiliary Interventional Department of Beijing Tsinghua Chang Gung Hospital, Beijing, China; we followed up with the patients over a period of 30 days post-surgery. We used flow cytometry (FCM) to quantify the frequency of MDSCs in peripheral blood before TACE, 10 days after surgery and 30 days after surgery.

Results

MDSC frequency after GSM–TACE had a significant downward trend. Pre-TACE, it was 30.73% ± 11.93%, decreasing to 18.60% ± 11.37% at 10 days after operation. This decrease was not statistically significant (P > 0.05). MDSC frequency was even lower 30 days after TACE (7.63% ± 7.32%) than at 10 days after TACE (P < 0.05), and there was a significant difference compared with pre-TACE (P < 0.001). We evaluated tumor response at 30 days after GSM–TACE according to the Modified Response Evaluation Criteria in Solid Tumors (mRECIST), and all eight patients showed partial response (PR).

Conclusion

Our results confirmed that GSM–TACE was beneficial for improving anti-tumor immunity in the treatment of HCC.