Blocking TGF-β Signaling To Enhance The Efficacy Of Immune Checkpoint Inhibitor

Radiotherapy and immunology

The majority of cancer patients receive radiotherapy during the course of treatment, delivered with curative intent for local tumor control or as part of a multimodality regimen aimed at eliminating distant metastasis. A major focus of research has been DNA damage; however, in the past two decades, emphasis has shifted to the important role the immune system plays in radiotherapy-induced anti-tumor effects. Radiotherapy reprograms the tumor microenvironment, triggering DNA and RNA sensing cascades that activate innate immunity and ultimately enhance adaptive immunity. In opposition, radiotherapy also induces suppression of anti-tumor immunity, including recruitment of regulatory T cells, myeloid-derived suppressor cells, and suppressive macrophages. The balance of pro- and anti-tumor immunity is regulated in part by radiotherapy-induced chemokines and cytokines. Microbiota can also influence radiotherapy outcomes and is under clinical investigation. Blockade of the PD-1/PD-L1 axis and CTLA-4 has been extensively investigated in combination with radiotherapy; we include a review of clinical trials involving inhibition of these immune checkpoints and radiotherapy.

Immunocompetent murine model of Ewing sarcoma reveals role for TGFβ inhibition to enhance immune infiltrates in Ewing tumors during radiation

Ewing sarcoma (ES) is an aggressive cancer diagnosed in adolescents and young adults. The fusion oncoprotein (EWSR1::FLI1) that drives Ewing sarcoma is known to downregulate TGFBR2 expression (part of the TGFβ receptor). Because TGFBR2 is downregulated, it was thought that TGFβ likely plays an inconsequential role in Ewing biology. However, the expression of TGFβ in the Ewing tumor immune microenvironment (TIME) and functional impact of TGFβ in the TIME remains largely unknown given the historical lack of immunocompetent preclinical models. Here, we use single-cell RNAseq analysis of human Ewing tumors to show that immune cells, such as NK cells, are the largest source of TGFβ production in human Ewing tumors. We develop a humanized (immunocompetent) mouse model of ES and demonstrate distinct TME signatures and metastatic potential in these models as compared to tumors developed in immunodeficient mice. Using this humanized model, we study the effect of TGFβ inhibition on the Ewing TME during radiation therapy, a treatment that both enhances TGFβ activation and is used to treat aggressive ES. Utilizing a trivalent ligand TGFβ TRAP to inhibit TGFβ, we demonstrate that in combination with radiation, TGFβ inhibition both increases ES immune cell infiltration and decreases lung metastatic burden in vivo . The culmination of these data demonstrates the value of humanized models to address immunobiologic preclinical questions in Ewing sarcoma and suggests TGFβ inhibition as a promising intervention during radiation therapy to promote metastatic tumor control.

Current Landscape of Cancer Immunotherapy: Harnessing the Immune Arsenal to Overcome Immune Evasion

Cancer immune evasion represents a leading hallmark of cancer, posing a significant obstacle to the development of successful anticancer therapies. However, the landscape of cancer treatment has significantly evolved, transitioning into the era of immunotherapy from conventional methods such as surgical resection, radiotherapy, chemotherapy, and targeted drug therapy. Immunotherapy has emerged as a pivotal component in cancer treatment, harnessing the body's immune system to combat cancer and offering improved prognostic outcomes for numerous patients. The remarkable success of immunotherapy has spurred significant efforts to enhance the clinical efficacy of existing agents and strategies. Several immunotherapeutic approaches have received approval for targeted cancer treatments, while others are currently in preclinical and clinical trials. This review explores recent progress in unraveling the mechanisms of cancer immune evasion and evaluates the clinical effectiveness of diverse immunotherapy strategies, including cancer vaccines, adoptive cell therapy, and antibody-based treatments. It encompasses both established treatments and those currently under investigation, providing a comprehensive overview of efforts to combat cancer through immunological approaches. Additionally, the article emphasizes the current developments, limitations, and challenges in cancer immunotherapy. Furthermore, by integrating analyses of cancer immunotherapy resistance mechanisms and exploring combination strategies and personalized approaches, it offers valuable insights crucial for the development of novel anticancer immunotherapeutic strategies.

Advances and Challenges in Targeting TGF-β Isoforms for Therapeutic Intervention of Cancer: A Mechanism-Based Perspective

The TGF-β family is a group of 25 kDa secretory cytokines, in mammals consisting of three dimeric isoforms (TGF-βs 1, 2, and 3), each encoded on a separate gene with unique regulatory elements. Each isoform plays unique, diverse, and pivotal roles in cell growth, survival, immune response, and differentiation. However, many researchers in the TGF-β field often mistakenly assume a uniform functionality among all three isoforms. Although TGF-βs are essential for normal development and many cellular and physiological processes, their dysregulated expression contributes significantly to various diseases. Notably, they drive conditions like fibrosis and tumor metastasis/progression. To counter these pathologies, extensive efforts have been directed towards targeting TGF-βs, resulting in the development of a range of TGF-β inhibitors. Despite some clinical success, these agents have yet to reach their full potential in the treatment of cancers. A significant challenge rests in effectively targeting TGF-βs' pathological functions while preserving their physiological roles. Many existing approaches collectively target all three isoforms, failing to target just the specific deregulated ones. Additionally, most strategies tackle the entire TGF-β signaling pathway instead of focusing on disease-specific components or preferentially targeting tumors. This review gives a unique historical overview of the TGF-β field often missed in other reviews and provides a current landscape of TGF-β research, emphasizing isoform-specific functions and disease implications. The review then delves into ongoing therapeutic strategies in cancer, stressing the need for more tools that target specific isoforms and disease-related pathway components, advocating mechanism-based and refined approaches to enhance the effectiveness of TGF-β-targeted cancer therapies.

A Hybrid Nanoadjuvant Simultaneously Depresses PD-L1/TGF-β1 and Activates cGAS-STING Pathway to Overcome Radio-Immunotherapy Resistance

Currently, certain cancer patients exhibit resistance to radiotherapy due to reduced DNA damage under hypoxic conditions and acquired immune tolerance triggered by transforming growth factor-β1 (TGF-β1) and membrane-localized programmed death ligand-1 (PD-L1). Meanwhile, cytoplasm-distributed PD-L1 induces radiotherapy resistance through accelerating DNA damage repair (DDR). However, the disability of clinically used PD-L1 antibodies in inhibiting cytoplasm-distributed PD-L1 limits their effectiveness. Therefore, a nanoadjuvant is developed to sensitize cancer to radiotherapy via multi-level immunity activation through depressing PD-L1 and TGF-β1 by triphenylphosphine-derived metformin, and activating the cGAS-STING pathway by generating Mn2+ from MnO2 and producing more dsDNA via reversing tumor hypoxia and impairing DDR. Thus, Tpp-Met@MnO2@Alb effectively enhances the efficiency of radiotherapy to inhibit the progression of irradiated local and abscopal tumors and tumor lung metastases, offering a long-term memory of antitumor immunity without discernible side effects. Overall, Tpp-Met@MnO2@Alb has the potential to be clinically applied for overcoming radio-immunotherapy resistance.

The enhanced antitumor activity of bispecific antibody targeting PD-1/PD-L1 signaling

The programmed cell death 1 (PD-1) signaling pathway, a key player in immune checkpoint regulation, has become a focal point in cancer immunotherapy. In the context of cancer, upregulated PD-L1 on tumor cells can result in T cell exhaustion and immune evasion, fostering tumor progression. The advent of PD-1/PD-L1 inhibitor has demonstrated clinical success by unleashing T cells from exhaustion. Nevertheless, challenges such as resistance and adverse effects have spurred the exploration of innovative strategies, with bispecific antibodies (BsAbs) emerging as a promising frontier. BsAbs offer a multifaceted approach to cancer immunotherapy by simultaneously targeting PD-L1 and other immune regulatory molecules. We focus on recent advancements in PD-1/PD-L1 therapy with a particular emphasis on the development and potential of BsAbs, especially in the context of solid tumors. Various BsAb products targeting PD-1 signaling are discussed, highlighting their unique mechanisms of action and therapeutic potential. Noteworthy examples include anti-TGFβ × PD-L1, anti-CD47 × PD-L1, anti-VEGF × PD-L1, anti-4-1BB × PD-L1, anti-LAG-3 × PD-L1, and anti-PD-1 × CTLA-4 BsAbs. Besides, we summarize ongoing clinical studies evaluating the efficacy and safety of these innovative BsAb agents. By unraveling the intricacies of the tumor microenvironment and harnessing the synergistic effects of anti-PD-1/PD-L1 BsAbs, there exists the potential to elevate the precision and efficacy of cancer immunotherapy, ultimately enabling the development of personalized treatment strategies tailored to individual patient profiles.

SMAD7 expression in CAR-T cells improves persistence and safety for solid tumors

Despite the tremendous progress of chimeric antigen receptor T (CAR-T) cell therapy in hematological malignancies, their application in solid tumors has been limited largely due to T-cell exhaustion in the tumor microenvironment (TME) and systemic toxicity caused by excessive cytokine release. As a key regulator of the immunosuppressive TME, TGF-β promotes cytokine synthesis via the NF-κB pathway. Here, we coexpressed SMAD7, a suppressor of TGF-β signaling, with a HER2-targeted CAR in engineered T cells. These novel CAR-T cells displayed high cytolytic efficacy and were resistant to TGF-β-triggered exhaustion, which enabled sustained tumoricidal capacity after continuous antigen exposure. Moreover, SMAD7 substantially reduced the production of inflammatory cytokines by antigen-primed CAR-T cells. Mechanistically, SMAD7 downregulated TGF-β receptor I and abrogated the interplay between the TGF-β and NF-κB pathways in CAR-T cells. As a result, these CAR-T cells persistently inhibited tumor growth and promoted the survival of tumor-challenged mice regardless of the hostile tumor microenvironment caused by a high concentration of TGF-β. SMAD7 coexpression also enhanced CAR-T-cell infiltration and persistent activation in patient-derived tumor organoids. Therefore, our study demonstrated the feasibility of SMAD7 coexpression as a novel approach to improve the efficacy and safety of CAR-T-cell therapy for solid tumors.

Emerging strategy for the treatment of urothelial carcinoma: Advances in antibody-drug conjugates combination therapy

Urothelial carcinoma (UC) is a prevalent malignant tumor involving the urinary system. Although there are various treatment modalities, including surgery, chemotherapy, and immune checkpoint inhibitor (ICI) therapy, some patients experience disease recurrence and metastasis with poor prognosis and dismal long-term survival. Antibody-drug conjugates (ADCs), which combine the targeting ability of antibody drugs with the cytotoxicity of chemotherapeutic drugs, have recently emerged as a prominent research focus in the development of individualized precision cancer therapy. Although ADCs have improved the overall response rate in patients with UC, their effectiveness remains limited. Currently, ADC-based combination therapies, particularly ADC combined with ICIs, have demonstrated promising efficacy. This combination approach has advanced the treatment of UC, exhibiting the potential to become the standard first-line therapy for advanced UC in the future. This article reviewed clinical trials involving ADC-based combination therapy for UC and discussed the possible challenges and future perspectives to provide guidance for the clinical treatment of UC.

Design and engineering of bispecific antibodies: insights and practical considerations

Bispecific antibodies (bsAbs) have attracted significant attention due to their dual binding activity, which permits simultaneous targeting of antigens and synergistic binding effects beyond what can be obtained even with combinations of conventional monospecific antibodies. Despite the tremendous therapeutic potential, the design and construction of bsAbs are often hampered by practical issues arising from the increased structural complexity as compared to conventional monospecific antibodies. The issues are diverse in nature, spanning from decreased biophysical stability from fusion of exogenous antigen-binding domains to antibody chain mispairing leading to formation of antibody-related impurities that are very difficult to remove. The added complexity requires judicious design considerations as well as extensive molecular engineering to ensure formation of high quality bsAbs with the intended mode of action and favorable drug-like qualities. In this review, we highlight and summarize some of the key considerations in design of bsAbs as well as state-of-the-art engineering principles that can be applied in efficient construction of bsAbs with diverse molecular formats.

The multifaceted role of Fragile X-Related Protein 1 (FXR1) in cellular processes: an updated review on cancer and clinical applications

RNA-binding proteins (RBPs) modulate the expression level of several target RNAs (such as mRNAs) post-transcriptionally through interactions with unique binding sites in the 3'-untranslated region. There is mounting information that suggests RBP dysregulation plays a significant role in carcinogenesis. However, the function of FMR1 autosomal homolog 1(FXR1) in malignancies is just beginning to be unveiled. Due to the diversity of their RNA-binding domains and functional adaptability, FXR1 can regulate diverse transcript processing. Changes in FXR1 interaction with RNA networks have been linked to the emergence of cancer, although the theoretical framework defining these alterations in interaction is insufficient. Alteration in FXR1 expression or localization has been linked to the mRNAs of cancer suppressor genes, cancer-causing genes, and genes involved in genomic expression stability. In particular, FXR1-mediated gene regulation involves in several cellular phenomena related to cancer growth, metastasis, epithelial-mesenchymal transition, senescence, apoptosis, and angiogenesis. FXR1 dysregulation has been implicated in diverse cancer types, suggesting its diagnostic and therapeutic potential. However, the molecular mechanisms and biological effects of FXR1 regulation in cancer have yet to be understood. This review highlights the current knowledge of FXR1 expression and function in various cancer situations, emphasizing its functional variety and complexity. We further address the challenges and opportunities of targeting FXR1 for cancer diagnosis and treatment and propose future directions for FXR1 research in oncology. This work intends to provide an in-depth review of FXR1 as an emerging oncotarget with multiple roles and implications in cancer biology and therapy.

Knowledge mapping of immunotherapy in cervical carcinoma: a bibliometric analysis (2000-2023)

Background

Cervical carcinoma is a type of malignant tumor that primarily develops in the cervix, the lower part of the uterus. In recent years, Despite the considerable progress made in immunotherapy research for cervical carcinoma, an important aspect has been largely overlooked - the absence of a comprehensive bibliometric analysis in this field. By employing bibliometric techniques, this study aims to fill this gap and provide a comprehensive overview of the knowledge structure and research hotspots within the realm of immunotherapy in cervical carcinoma.

Method

A comprehensive search was conducted on the web of science core collection(WoSCC) database to identify publications related to immunotherapy specifically for the treatment of cervical carcinoma. The search spanned the period from the year 2000 to 2023. Several analytical tools were employed. These included VOSviewers, CiteSpace, and the R package "bibliometrix".

Results

A total of 654 research articles from 66 different countries have been included in the analysis. The United States and China have emerged as the leading countries in publishing research on immunotherapy in cervical carcinoma. Leiden University and Memorial Sloan-Kettering Cancer Center from the Netherlands and the United States respectively have a close cooperation. Fudan University from China and the German Cancer Research Center are also among the key institutions leading research in this area. Frontiers in Oncology has emerged as the most popular and widely recognized publication in the field of immunotherapy in cervical carcinoma. Journal of Clinical Oncology is frequently cited by researchers in this area. Van Der Burg, Sjoerd H has published the highest number of papers. Tewari, Krishnansu S has been the most co-cited author. Keywords such as PD-L1, chemotherapy, and immune checkpoint inhibitors have gained significant attention in recent years.

Conclusion

This is the first bibliometric study that comprehensively summarizes the research trends and developments of immunotherapy in cervical carcinoma. This groundbreaking study not only summarizes the current research trends and developments in immunotherapy for cervical carcinoma but also provides a reference for scholars studying the treatment of cervical cancer.

Breaking the mold: Overcoming resistance to immune checkpoint inhibitors

Immune checkpoint blockade-based therapies are effective against a sorts of cancers. However, drug resistance is a problem that cannot be ignored. This review intends to elucidate the mechanisms underlying drug tolerance induced by PD-1/PD-L1 inhibitors, as well as to outline proposed mechanism-based combination therapies and small molecule drugs that target intrinsic immunity and immune checkpoints. According to the differences of patients and types of cancer, the optimization of individualized combination therapy will help to enhance PD-1/PD-L1-mediated immunoregulation, reduce chemotherapy resistance, and provide new ideas for chemotherapy-resistant cancer.

The Role of the Transforming Growth Factor-β Signaling Pathway in Gastrointestinal Cancers

Transforming growth factor-β (TGF-β) has attracted attention as a tumor suppressor because of its potent growth-suppressive effect on epithelial cells. Dysregulation of the TGF-β signaling pathway is considered to be one of the key factors in carcinogenesis, and genetic alterations affecting TGF-β signaling are extraordinarily common in cancers of the gastrointestinal system, such as hereditary nonpolyposis colon cancer and pancreatic cancer. Accumulating evidence suggests that TGF-β is produced from various types of cells in the tumor microenvironment and mediates extracellular matrix deposition, tumor angiogenesis, the formation of CAFs, and suppression of the anti-tumor immune reaction. It is also being considered as a factor that promotes the malignant transformation of cancer, particularly the invasion and metastasis of cancer cells, including epithelial-mesenchymal transition. Therefore, elucidating the role of TGF-β signaling in carcinogenesis, cancer invasion, and metastasis will provide novel basic insight for diagnosis and prognosis and the development of new molecularly targeted therapies for gastrointestinal cancers. In this review, we outline an overview of the complex mechanisms and functions of TGF-β signaling. Furthermore, we discuss the therapeutic potentials of targeting the TGF-β signaling pathway for gastrointestinal cancer treatment and discuss the remaining challenges and future perspectives on targeting this pathway.

Recent advances in targeted strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC), a highly aggressive subtype of breast cancer, negatively expresses estrogen receptor, progesterone receptor, and the human epidermal growth factor receptor 2 (HER2). Although chemotherapy is the main form of treatment for patients with TNBC, the effectiveness of chemotherapy for TNBC is still limited. The search for more effective therapies is urgent. Multiple targeted therapeutic strategies have emerged according to the specific molecules and signaling pathways expressed in TNBC. These include PI3K/AKT/mTOR inhibitors, epidermal growth factor receptor inhibitors, Notch inhibitors, poly ADP-ribose polymerase inhibitors, and antibody-drug conjugates. Moreover, immune checkpoint inhibitors, for example, pembrolizumab, atezolizumab, and durvalumab, are widely explored in the clinic. We summarize recent advances in targeted therapy and immunotherapy in TNBC, with the aim of serving as a reference for the development of individualized treatment of patients with TNBC in the future.

Construction of a Matrix Cancer-Associated Fibroblast Signature Gene-Based Risk Prognostic Signature for Directing Immunotherapy in Patients with Breast Cancer Using Single-Cell Analysis and Machine Learning

Cancer-associated fibroblasts (CAFs) are heterogeneous constituents of the tumor microenvironment involved in the tumorigenesis, progression, and therapeutic responses of tumors. This study identified four distinct CAF subtypes of breast cancer (BRCA) using single-cell RNA sequencing (RNA-seq) data. Of these, matrix CAFs (mCAFs) were significantly associated with tumor matrix remodeling and strongly correlated with the transforming growth factor (TGF)-β signaling pathway. Consensus clustering of The Cancer Genome Atlas (TCGA) BRCA dataset using mCAF single-cell characteristic gene signatures segregated samples into high-fibrotic and low-fibrotic groups. Patients in the high-fibrotic group exhibited a significantly poor prognosis. A weighted gene co-expression network analysis and univariate Cox analysis of bulk RNA-seq data revealed 17 differential genes with prognostic values. The mCAF risk prognosis signature (mRPS) was developed using 10 machine learning algorithms. The clinical outcome predictive accuracy of the mRPS was higher than that of the conventional TNM staging system. mRPS was correlated with the infiltration level of anti-tumor effector immune cells. Based on consensus prognostic genes, BRCA samples were classified into the following two subtypes using six machine learning algorithms (accuracy > 90%): interferon (IFN)-γ-dominant (immune C2) and TGF-β-dominant (immune C6) subtypes. Patients with mRPS downregulation were associated with improved prognosis, suggesting that they can potentially benefit from immunotherapy. Thus, the mRPS model can stably predict BRCA prognosis, reflect the local immune status of the tumor, and aid clinical decisions on tumor immunotherapy.

Synergistic efficacy of simultaneous anti-TGF-β/VEGF bispecific antibody and PD-1 blockade in cancer therapy

BACKGROUND

Recently, therapeutic antibodies against programmed cell death 1 (PD-1) and its ligand (PD-L1) have exerted potent anticancer effect in a variety of tumors. However, blocking the PD-1/PD-L1 axis alone is not sufficient to restore normal immune response. Other negative regulators of antitumor immunity, like TGF-β and VEGFA, are also involved in immune escape of tumor cells and induce immunotherapy resistance.

METHODS

We developed a novel anti-TGF-β/VEGF bispecific antibody Y332D based on the Nano-YBODY™ technology platform. The CCK-8, flow cytometry, SBE4 luciferase reporter assay, western blotting and transwell assays were used to measure the biological activities of the anti-TGF-β moiety. The NFAT luciferase reporter assay, luminescent cell viability assay and tube formation assay were used to measure the biological activities of the anti-VEGF moiety. The in vivo anticancer efficacy of Y332D alone or in combination with PD-1 blockade was evaluated in H22, EMT-6, 4T1, and AKT/Ras-driven murine hepatocellular carcinoma tumor models. Immunofluorescent staining, flow cytometry, RNA-seq and quantitative RT-PCR were adopted to analyze the alterations in the tumor microenvironment.

RESULTS

Y332D could maintain specific binding affinities for TGF-β and VEGFA. Y332D almost entirely counteracted the in vitro biological functions of TGF-β and VEGFA, including immunosuppression, activated TGF-β signaling, epithelial-mesenchymal transition (EMT), activated VEGF/VEGFR signaling, HUVEC proliferation and tube formation. The in vivo experiment data demonstrated that Y332D was more effective in inhibiting tumor growth and metastasis than anti-TGF-β and anti-VEGF monotherapies. In combination therapies, Y332D plus PD-1 blockade exhibited the most potent and durable anticancer effect. Mechanistically, Y332D plus PD-1 blockade upregulated the density and function of tumor-infiltrating lymphocytes and exerted reinvigorated antitumor immunity.

CONCLUSION

Y332D could simultaneously block TGF-β and VEGF signalings. In comparison with the monotherapies, Y332D combined with PD-1 blockade exerts superior antitumor effect through improving immune microenvironment.

Bispecific antibody targeting TGF-β and PD-L1 for synergistic cancer immunotherapy

The PD-1/PD-L1 signaling pathway plays a crucial role in cancer immune evasion, and the use of anti-PD-1/PD-L1 antibodies represents a significant milestone in cancer immunotherapy. However, the low response rate observed in unselected patients and the development of therapeutic resistance remain major obstacles to their clinical application. Accumulating studies showed that overexpressed TGF-β is another immunosuppressive factor apart from traditional immune checkpoints. Actually, the effects of PD-1 and TGF-β pathways are independent and interactive, which work together contributing to the immune evasion of cancer cell. It has been verified that blocking TGF-β and PD-L1 simultaneously could enhance the efficacy of PD-L1 monoclonal antibody and overcome its treatment resistance. Based on the bispecific antibody or fusion protein technology, multiple bispecific and bifunctional antibodies have been developed. In the preclinical and clinical studies, these updated antibodies exhibited potent anti-tumor activity, superior to anti-PD-1/PD-L1 monotherapies. In the review, we summarized the advances of bispecific antibodies targeting TGF-β and PD-L1 in cancer immunotherapy. We believe these next-generation immune checkpoint inhibitors would substantially alter the cancer treatment paradigm, especially in anti-PD-1/PD-L1-resistant patients.

Targeting LSD1 in tumor immunotherapy: rationale, challenges and potential

Lysine-specific demethylase 1 (LSD1) is an enzyme that removes lysine methylation marks from nucleosome histone tails and plays an important role in cancer initiation, progression, metastasis, and recurrence. Recent research shows that LSD1 regulates tumor cells and immune cells through multiple upstream and downstream pathways, enabling tumor cells to adapt to the tumor microenvironment (TME). As a potential anti-tumor treatment strategy, immunotherapy has developed rapidly in the past few years. However, most patients have a low response rate to available immune checkpoint inhibitors (ICIs), including anti-PD-(L)1 therapy and CAR-T cell therapy, due to a broad array of immunosuppressive mechanisms. Notably, inhibition of LSD1 turns "cold tumors" into "hot tumors" and subsequently enhances tumor cell sensitivity to ICIs. This review focuses on recent advances in LSD1 and tumor immunity and discusses a potential therapeutic strategy for combining LSD1 inhibition with immunotherapy.

Integrative analysis revealed that distinct cuprotosis patterns reshaped tumor microenvironment and responses to immunotherapy of colorectal cancer

Background

Cuprotosis is a novel form of programmed cell death that involves direct targeting of key enzymes in the tricarboxylic acid (TCA) cycle by excess copper and may result in mitochondrial metabolic dysfunction. However, whether cuprotosis may mediate the tumor microenvironment (TME) and immune regulation in colorectal cancer (CRC) remains unclear.

Methods

Ten cuprotosis-related genes were selected and unsupervised consensus clustering was performed to identify the cuprotosis patterns and the correlated TME characteristics. Using principal component analysis, a COPsig score was established to quantify cuprotosis patterns in individual patients. The top 9 most important cuprotosis signature genes were analyzed using single-cell transcriptome data.

Results

Three distinct cuprotosis patterns were identified. The TME cell infiltration characteristics of three patterns were associated with immune-excluded, immune-desert, and immune-inflamed phenotype, respectively. Based on individual cuprotosis patterns, patients were assigned into high and low COPsig score groups. Patients with a higher COPsig score were characterized by longer overall survival time, lower immune cell as well as stromal infiltration, and greater tumor mutational burden. Moreover, further analysis demonstrated that CRC patients with a higher COPsig score were more likely to respond to immune checkpoint inhibitors and 5-fluorouracil chemotherapy. Single-cell transcriptome analysis indicated that cuprotosis signature genes recruited tumor-associated macrophages to TME through the regulation of TCA and the metabolism of glutamine and fatty acid, thus influencing the prognosis of CRC patients.

Conclusion

This study indicated that distinct cuprotosis patterns laid a solid foundation to the explanation of heterogeneity and complexity of individual TME, thus guiding more effective immunotherapy as well as adjuvant chemotherapy strategies.

Targeting RNA Exonuclease XRN1 Potentiates Efficacy of Cancer Immunotherapy

Despite the remarkable clinical responses achieved with immune checkpoint blockade therapy, the response rate is relatively low and only a subset of patients can benefit from the treatment. Aberrant RNA accumulation can mediate IFN signaling and stimulate an immune response, suggesting that targeting RNA decay machinery might sensitize tumor cells to immunotherapy. With this in mind, we identified an RNA exoribonuclease, XRN1, as a potential therapeutic target to suppress RNA decay and stimulate antitumor immunity. Silencing of XRN1 suppressed tumor growth in syngeneic immunocompetent mice and potentiated immunotherapy efficacy, while silencing of XRN1 alone did not affect tumor growth in immunodeficient mice. Mechanistically, XRN1 depletion activated IFN signaling and the viral defense pathway; both pathways play determinant roles in regulating immune evasion. Aberrant RNA-sensing signaling proteins (RIG-I/MAVS) mediated the expression of IFN genes, as depletion of each of them blunted the elevation of antiviral/IFN signaling in XRN1-silenced cells. Analysis of pan-cancer CRISPR-screening data indicated that IFN signaling triggered by XRN1 silencing is a common phenomenon, suggesting that the effect of XRN1 silencing may be extended to multiple types of cancers. Overall, XRN1 depletion triggers aberrant RNA-mediated IFN signaling, highlighting the importance of the aberrant RNA-sensing pathway in regulating immune responses. These findings provide the molecular rationale for developing XRN1 inhibitors and exploring their potential clinical application in combination with cancer immunotherapy.

SIGNIFICANCE

Targeting XRN1 activates an intracellular innate immune response mediated by RNA-sensing signaling and potentiates cancer immunotherapy efficacy, suggesting inhibition of RNA decay machinery as a novel strategy for cancer treatment.

Efficacy of therapies targeting TGF-β in solid tumors: a systematic review and meta-analysis of clinical trials

Aims: A comprehensive meta-analysis was conducted to explore the efficacy of TGF-β blockade therapies in solid tumors. Patients & methods: Results of overall survival (OS), progression-free survival (PFS), time to progression (TTP) and overall response rate (ORR) with their 95% CI were calculated. Also, subgroup analyses were conducted according to the categories of TGF-β blocker alone or combined with chemotherapy or radiotherapy. Results: Overall OS, PFS, TTP and ORR were 10.5 months (95% CI: 7.76-13.25), 2.54 months (95% CI: 1.66-3.43), 4.69 months (95% CI: 3.18-6.21) and 0.83% (95% CI: 0.82-0.85), respectively. Conclusion: Collectively, TGF-β blockade combined with chemotherapy or radiotherapy showed more favorable clinical outcomes than monotherapy using TGF-β blockade.

Regulation of T Cell Activation and Metabolism by Transforming Growth Factor-Beta

Transforming growth factor beta (TGFβ) receptor signalling regulates T cell development, differentiation and effector function. Expression of the immune-associated isoform of this cytokine, TGFβ1, is absolutely required for the maintenance of immunological tolerance in both mice and humans, whilst context-dependent TGFβ1 signalling regulates the differentiation of both anti- and pro-inflammatory T cell effector populations. Thus, distinct TGFβ-dependent T cell responses are implicated in the suppression or initiation of inflammatory and autoimmune diseases. In cancer settings, TGFβ signals contribute to the blockade of anti-tumour immune responses and disease progression. Given the key functions of TGFβ in the regulation of immune responses and the potential for therapeutic targeting of TGFβ-dependent pathways, the mechanisms underpinning these pleiotropic effects have been the subject of much investigation. This review focuses on accumulating evidence suggesting that modulation of T cell metabolism represents a major mechanism by which TGFβ influences T cell immunity.

Macrophage and monocyte subsets as new therapeutic targets in cancer immunotherapy

The introduction of immune checkpoint inhibitors (ICIs) for the treatment of solid cancers dramatically turned the tables in clinical routine. However, therapy success is still limited with up to 70% of non-responders in patients with ICI treatment. Traditionally, most immunotherapy approaches aim at directly stimulating anti-tumor T cell responses. More recently, tumor-associated macrophages have come into focus due to their predominance in solid tumors. Intensive cross-talk with tumor cells and immune as well as stromal cells within the tumor microenvironment can drive either pro- or anti-tumorigenic macrophage phenotypes. In turn, tumor-associated macrophages strongly shape cytokine and metabolite levels in the tumor microenvironment and thus are central players in anti-tumor immunity. Thus, ambivalent macrophage populations exist which raises therapeutic possibilities to either enhance or diminish their functionality. However, molecular signals controlling tumor-associated macrophage polarization are incompletely understood. Gaining in-depth understanding of monocyte/macrophage properties both in circulation and within distinct tumor microenvironments would (i) allow the development of new therapeutic approaches, and (ii) could additionally aid our understanding of underlying mechanisms limiting current therapy with the option of combinatorial therapies to increase efficacy. In this review, we summarize recent data addressing heterogeneity of tumor-associated macrophage populations and we discuss strategies to target macrophages using known molecular pathways with the potential for straight-forward clinical application.

Mutational analysis of microsatellite-stable gastrointestinal cancer with high tumour mutational burden: a retrospective cohort study

BACKGROUND

Genomic signatures contributing to high tumour mutational burden (TMB-H) independent from mismatch-repair deficiency (dMMR) or microsatellite instability-high (MSI-H) status are not well studied. We aimed to characterise molecular features of microsatellite stable (MSS) TMB-H gastrointestinal tumours.

METHODS

Molecular alterations of 48 606 gastrointestinal tumours from Caris Life Sciences (CARIS) identified with next-generation sequencing were compared among MSS-TMB-H, dMMR/MSI-H, and MSS-TMB-low (L) tumours, using χ2 or Fisher's exact tests. Antitumour immune response within the tumour environment was predicted by analysing the infiltration of immune cells and immune signatures using The Cancer Genome Atlas database. The Kaplan-Meier method and the log-rank test were used to evaluate the impact of gene alterations on the efficacy of immune checkpoint inhibitors in MSS gastrointestinal cancers from the CARIS database, a Memorial Sloan Kettering Cancer Center cohort, and a Peking University Cancer Hospital cohort.

FINDINGS

MSS-TMB-H was observed in 1600 (3·29%) of 48 606 tumours, dMMR/MSI-H in 2272 (4·67%), and MSS-TMB-L in 44 734 (92·03%). Gene mutations in SMAD2, MTOR, NFE2L2, RB1, KEAP1, TERT, and RASA1 might impair antitumour immune response despite TMB-H, while mutations in 16 other genes (CDC73, CTNNA1, ERBB4, EZH2, JAK2, MAP2K1, MAP2K4, PIK3R1, POLE, PPP2R1A, PPP2R2A, PTPN11, RAF1, RUNX1, STAG2, and XPO1) were related to TMB-H with enhanced antitumour immune response independent of dMMR/MSI-H, constructing a predictive model (modified TMB [mTMB]) for immune checkpoint inhibitor efficacy. Patients with any mutation in the mTMB gene signature, in comparison with patients with mTMB wildtype tumours, showed a superior survival benefit from immune checkpoint inhibitors in MSS gastrointestinal cancers in the CARIS cohort (n=95, median overall survival 18·77 months [95% CI 17·30-20·23] vs 7·03 months [5·73-8·34]; hazard ratio 0·55 [95% CI 0·31-0·99], p=0·044). In addition, copy number amplification in chromosome 11q13 (eg, CCND1, FGF genes) was more prevalent in MSS-TMB-H tumours than in the dMMR/MSI-H or MSS-TMB-L subgroups.

INTERPRETATION

Not all mutations related to TMB-H can enhance antitumour immune response. More composite biomarkers should be investigated (eg, mTMB signature) to tailor treatment with immune checkpoint inhibitors. Our data also provide novel insights for the combination of immune checkpoint inhibitors and drugs targeting cyclin D1 or FGFs.

FUNDING

US National Cancer Institute, Gloria Borges WunderGlo Foundation, Dhont Family Foundation, Gene Gregg Pancreas Research Fund, San Pedro Peninsula Cancer Guild, Daniel Butler Research Fund, Victoria and Philip Wilson Research Fund, Fong Research Project, Ming Hsieh Research Fund, Shanghai Sailing Program, China National Postdoctoral Program for Innovative Talents, China Postdoctoral Science Foundation, National Natural Science Foundation of China.

The Sesquiterpene Lactone-Rich Fraction of Inula helenium L. Enhances the Antitumor Effect of Anti-PD-1 Antibody in Colorectal Cancer: Integrative Phytochemical, Transcriptomic, and Experimental Analyses

Treatment strategies combining immune checkpoint inhibitors with sesquiterpene lactones have attracted much attention as a promising approach for cancer treatment. We systemically analyzed gene expression profiles of cells in response to two major sesquiterpene lactones, alantolactone and isoalantolactone, and determined whether the sesquiterpene lactone-rich fraction of Inula helenium L. (SFIH) enhances the antitumor effect of anti-PD-1 antibody in MC38 colorectal cancer-bearing mice. Gene expression and pathway analysis using RNA sequencing data were used to identify the SFIH-driven combined activity with anti-PD-1 antibody. The results showed that SFIH significantly enhanced the antitumor effect of anti-PD-1 antibody by reducing tumor growth and increasing the survival time of mice. Specifically, SFIH exhibited antitumor activity when combined with anti-PD-1 antibody, and the effects were further enhanced compared with monotherapy. An analysis of immune cells indicated that combination treatment with SFIH and anti-PD-1 antibody significantly increased the proportion of CD8⁺ T cells. Moreover, combination treatment enhanced antitumor immunity by decreasing the population of myeloid-derived suppressor cells and increasing the number of M1-like macrophages. Pathway enrichment analysis revealed that combination therapy activated immune-related pathways to a greater extent than monotherapy. In conclusion, our integrative analysis demonstrates that SFIH enhances the response of murine tumors to anti-PD-1 antibody. These findings provide insight into developing integrative therapeutics and molecular data for the use of natural products as an adjunct treatment for colorectal cancer.

Breast cancer heterogeneity and its implication in personalized precision therapy

Breast cancer heterogeneity determines cancer progression, treatment effects, and prognosis. However, the precise mechanism for this heterogeneity remains unknown owing to its complexity. Here, we summarize the origins of breast cancer heterogeneity and its influence on disease progression, recurrence, and therapeutic resistance. We review the possible mechanisms of heterogeneity and the research methods used to analyze it. We also highlight the importance of cell interactions for the origins of breast cancer heterogeneity, which can be further categorized into cooperative and competitive interactions. Finally, we provide new insights into precise individual treatments based on heterogeneity.

Cancer therapy with immune checkpoint inhibitor and CSF-1 blockade: A mathematical model

Immune checkpoint inhibitors (ICIs) introduced in recent years have revolutionized the treatment of many metastatic cancers. However, data suggest that treatment has benefits only in a limited percentage of patients, and that this is due to immune suppression of the tumor microenvironment (TME). Anti-tumor inflammatory macrophages (M1), which are attracted to the TME, are converted by tumor secreted cytokines, such as CSF-1, to pro-tumor anti-inflammatory macrophages (M2), or tumor associated macrophages (TAMs), which block the anti-tumor T cells. In the present paper we develop a mathematical model that represents the interactions among the immune cells and cancer in terms of differential equations. The model can be used to assess treatments of combination therapy of anti-PD-1 with anti-CSF-1. Examples are given in comparing the efficacy among different strategies for anti-CSF-1 dosing in a setup of clinical trials.

Establishment and evaluation of an in vitro blast lung injury model using alveolar epithelial cells

Background

Gas explosion is a fatal disaster commonly occurred in coal mining and often causes systematic physical injuries, of which blast lung injury is the primary one and has not yet been fully investigated due to the absence of disease models. To facilitate studies of this field, we constructed an in vitro blast lung injury model using alveolar epithelial cells.

Methods

We randomly divided the alveolar epithelial cells into the control group and blast wave group, cells in the blast wave group were stimulated with different strengths of blast wave, and cells in the control group received sham intervention. Based on the standards we set up for a successful blast injury model, the optimal modeling conditions were studied on different frequencies of blast wave, modeling volume, cell incubation duration, and cell density. The changes of cell viability, apoptosis, intracellular oxidative stress, and inflammation were measured.

Results

We found that cell viability decreased by approximately 50% at 6 h after exposing to 8 bar energy of blast wave, then increased with the extension of culture time and reached to (74.33 ± 9.44) % at 12 h. By applying 1000 ~ 2500 times of shock wave to 1 ~ 5 × 105 cells /ml, the changes of cell viability could well meet the modeling criteria. In parallel, the content of reactive oxide species (ROS), malonaldehyde (MDA), interleukin 18 (IL-18), tumor necrosis factor alpha (TNF-α), and transforming growth factor beta (TGF-β) increased in the blast wave group, while superoxide dismutase (SOD) and Glutathione -S- transferase (GST) decreased, which were highly consistent with that of human beings with gas explosion-induced pulmonary injury.

Conclusion

An in vitro blast lung injury model is set up using a blast wave physiotherapy under 8 bar, 10 Hz blast wave on (1 ~ 5) ×105 alveolar epithelial cells for 1 000 times. This model is flexible, safe, and stable, and can be used for studies of lung injury caused by gas explosion and blast-associated other external forces.

TGF-β: A novel predictor and target for anti-PD-1/PD-L1 therapy

Transforming growth factor-β (TGF-β) signaling regulates multiple physiological processes, such as cell proliferation, differentiation, immune homeostasis, and wound healing. Besides, TGF-β plays a vital role in diseases, including cancer. Accumulating evidence indicates that TGF-β controls the composition and behavior of immune components in the tumor microenvironment (TME). Advanced cancers leverage TGF-β to reshape the TME and escape immune surveillance. TGF-β-mediated immune evasion is an unfavorable factor for cancer immunotherapy, especially immune checkpoint inhibitors (ICI). Numerous preclinical and clinical studies have demonstrated that hyperactive TGF-β signaling is closely associated with ICI resistance. It has been validated that TGF-β blockade synergizes with ICI and overcomes treatment resistance. TGF-β-targeted therapies, including trap and bispecific antibodies, have shown immense potential for cancer immunotherapy. In this review, we summarized the predictive value of TGF-β signaling and the prospects of TGF-β-targeted therapies for cancer immunotherapy.

Anti-TGF-β/PD-L1 bispecific antibody promotes T cell infiltration and exhibits enhanced antitumor activity in triple-negative breast cancer

BACKGROUND

Agents blocking programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) have been approved for triple-negative breast cancer (TNBC). However, the response rate of anti-PD-1/PD-L1 is still unsatisfactory, partly due to immunosuppressive factors such as transforming growth factor-beta (TGF-β). In our previous pilot study, the bispecific antibody targeting TGF-β and murine PD-L1 (termed YM101) showed potent antitumor effect. In this work, we constructed a bispecific antibody targeting TGF-β and human PD-L1 (termed BiTP) and explored the antitumor effect of BiTP in TNBC.

METHODS

BiTP was developed using Check-BODY^TM bispecific platform. The binding affinity of BiTP was measured by surface plasmon resonance, ELISA, and flow cytometry. The bioactivity was assessed by Smad and NFAT luciferase reporter assays, immunofluorescence, western blotting, and superantigen stimulation assays. The antitumor activity of BiTP was explored in humanized epithelial-mesenchymal transition-6-hPDL1 and 4T1-hPDL1 murine TNBC models. Immunohistochemical staining, flow cytometry, and bulk RNA-seq were used to investigate the effect of BiTP on immune cell infiltration.

RESULTS

BiTP exhibited high binding affinity to dual targets. In vitro experiments verified that BiTP effectively counteracted TGF-β-Smad and PD-L1-PD-1-NFAT signaling. In vivo animal experiments demonstrated that BiTP had superior antitumor activity relative to anti-PD-L1 and anti-TGF-β monotherapy. Mechanistically, BiTP decreased collagen deposition, enhanced CD8⁺ T cell penetration, and increased tumor-infiltrating lymphocytes. This improved tumor microenvironment contributed to the potent antitumor activity of BiTP.

CONCLUSION

BiTP retains parent antibodies' binding affinity and bioactivity, with superior antitumor activity to parent antibodies in TNBC. Our data suggest that BiTP might be a promising agent for TNBC treatment.

Immunotherapy for lung cancer combining the oligodeoxynucleotides of TLR9 agonist and TGF-β2 inhibitor

Tumor immunotherapies have shown promising antitumor effects, especially immune checkpoint inhibitors (ICIs). However, only 12.46% of the patients benefit from the ICIs, the rest of them shows limited effects on ICIs or even accelerates the tumor progression due to the lack of the immune cell infiltration and activation in the tumor microenvironment (TME). In this study, we administrated a combination of Toll-like receptor 9 (TLR9) agonist CpG ODN and Transforming growth factor-β2 (TGF-β2) antisense oligodeoxynucleotide TIO3 to mice intraperitoneally once every other day for a total of four injections, and the first injection was 24 h after LLC cell inoculation. We found that the combination induced the formation of TME toward the enrichment and activation of CD8⁺ T cells and NK cells, accompanied with a marked decrease of TGF-β2. The combined therapy also effectively inhibited the tumor growth and prolonged the survival of the mice, even protected the tumor-free mice from the tumor re-challenge. Both of CpG ODN and TIO3 are indispensable, because replacing CpG ODN with TLR9 inhibitor CCT ODN showed no antitumor effect, CpG ODN or TIO3 alone did not lead to ideal antitumor results. This effect was possibly initiated by the activation of dendritic cells at the tumor site. This systemic antitumor immunotherapy with a combination of the two oligonucleotides (an immune stimulant and an immunosuppressive cytokine inhibitor) before the tumor formation may provide a novel strategy for clinical prevention of the postoperative tumor recurrence.

The radiobiology of TGFβ

Ionizing radiation is a pillar of cancer therapy that is deployed in more than half of all malignancies. The therapeutic effect of radiation is attributed to induction of DNA damage that kills cancers cells, but radiation also affects signaling that alters the composition of the tumor microenvironment by activating transforming growth factor β (TGFβ). TGFβ is a ubiquitously expressed cytokine that acts as biological lynchpin to orchestrate phenotypes, the stroma, and immunity in normal tissue; these activities are subverted in cancer to promote malignancy, a permissive tumor microenvironment and immune evasion. The radiobiology of TGFβ unites targets at the forefront of oncology-the DNA damage response and immunotherapy. The cancer cell intrinsic and extrinsic network of TGFβ responses in the irradiated tumor form a barrier to both genotoxic treatments and immunotherapy response. Here, we focus on the mechanisms by which radiation induces TGFβ activation, how TGFβ regulates DNA repair, and the dynamic regulation of the tumor immune microenvironment that together oppose effective cancer therapy. Strategies to inhibit TGFβ exploit fundamental radiobiology that may be the missing link to deploying TGFβ inhibitors for optimal patient benefit from cancer treatment.

Combination of oral STING agonist MSA-2 and anti-TGF-β/PD-L1 bispecific antibody YM101: a novel immune cocktail therapy for non-inflamed tumors

BACKGROUND

Non-inflamed tumors, including immune-excluded and immune-desert tumors, are commonly resistant to anti-PD-1/PD-L1 (α-PD-1/PD-L1) therapy. Our previous study reported the potent antitumor activity of anti-TGF-β/PD-L1 bispecific antibody YM101 in immune-excluded tumors. However, YM101 had limited antitumor activity in immune-desert models. MSA-2 is a novel oral stimulator of interferon genes (STING) agonist, which activates the innate immune system and may synergize with YM101 in overcoming immunotherapy resistance.

METHODS

The dose-dependent effect of MSA-2 on STING signaling was determined by interferon-β level. The maturation and function of dendritic cell (DC) were measured by flow cytometry, RNA-seq, one-way mixed lymphocyte reaction (MLR), OVA peptide pulse, and cytokine/chemokine detection. The synergistic effect between MSA-2 and YM101 was assessed by one-way MLR. The macrophage activation was measured by flow cytometry and cytokine/chemokine detection. The in vivo antitumor activity of MSA-2 combined with YM101 was explored in syngeneic murine tumor models. After treatments, the alterations in the tumor microenvironment (TME) were detected by flow cytometry, immunohistochemistry staining, immunofluorescence staining, RNA-seq, and single-cell RNA-seq (scRNA-seq).

RESULTS

MSA-2 could promote the maturation and antigen presentation capability of murine DC. In the one-way MLR assay, MSA-2 synergized with YM101 in enhancing naive T cell activation. Moreover, MSA-2 stimulated the classical activation of macrophage, without significant influence on alternative activation. Further in vivo explorations showed that MSA-2 increased multiple proinflammatory cytokines and chemokines in the TME. MSA-2 combined with YM101 remarkedly retarded tumor growth in immune-excluded and immune-desert models, with superior antitumor activity to monotherapies. Flow cytometry, bulk RNA-seq, and scRNA-seq assays indicated that the combination therapy simultaneously boosted the innate and adaptive immunity, promoted antigen presentation, improved T cell migration and chemotaxis, and upregulated the numbers and activities of tumor-infiltrating lymphocytes.

CONCLUSION

Our results demonstrate that MSA-2 synergizes with YM101 in boosting antitumor immunity. This immune cocktail therapy effectively overcomes immunotherapy resistance in immune-excluded and immune-desert models.

Transforming growth factor-β in tumour development

Transforming growth factor-β (TGFβ) is a ubiquitous cytokine essential for embryonic development and postnatal tissue homeostasis. TGFβ signalling regulates several biological processes including cell growth, proliferation, apoptosis, immune function, and tissue repair following injury. Aberrant TGFβ signalling has been implicated in tumour progression and metastasis. Tumour cells, in conjunction with their microenvironment, may augment tumourigenesis using TGFβ to induce epithelial-mesenchymal transition, angiogenesis, lymphangiogenesis, immune suppression, and autophagy. Therapies that target TGFβ synthesis, TGFβ-TGFβ receptor complexes or TGFβ receptor kinase activity have proven successful in tissue culture and in animal models, yet, due to limited understanding of TGFβ biology, the outcomes of clinical trials are poor. Here, we review TGFβ signalling pathways, the biology of TGFβ during tumourigenesis, and how protein quality control pathways contribute to the tumour-promoting outcomes of TGFβ signalling.

Exhaust the exhausters: Targeting regulatory T cells in the tumor microenvironment

The concept of cancer immunotherapy has gained immense momentum over the recent years. The advancements in checkpoint blockade have led to a notable progress in treating a plethora of cancer types. However, these approaches also appear to have stalled due to factors such as individuals' genetic make-up, resistant tumor sub-types and immune related adverse events (irAE). While the major focus of immunotherapies has largely been alleviating the cell-intrinsic defects of CD8⁺ T cells in the tumor microenvironment (TME), amending the relationship between tumor specific CD4⁺ T cells and CD8⁺ T cells has started driving attention as well. A major roadblock to improve the cross-talk between CD4⁺ T cells and CD8⁺ T cells is the immune suppressive action of tumor infiltrating T regulatory (Treg) cells. Despite their indispensable in protecting tissues against autoimmune threats, Tregs have also been under scrutiny for helping tumors thrive. This review addresses how Tregs establish themselves at the TME and suppress anti-tumor immunity. Particularly, we delve into factors that promote Treg migration into tumor tissue and discuss the unique cellular and humoral composition of TME that aids survival, differentiation and function of intratumoral Tregs. Furthermore, we summarize the potential suppression mechanisms used by intratumoral Tregs and discuss ways to target those to ultimately guide new immunotherapies.

LINC00887 Fosters Development of Clear Cell Renal Cell Carcinoma via Inhibiting CD8+ T Cell Immune Infiltration

Background

lncRNAs affect adaptive and innate immunity of cancer via mediating functional states of immune cells, genes, and pathways. Nonetheless, little is known about the molecular mechanism of lncRNA-mediated CD8+ T cell immune infiltration in progression of clear cell renal cell carcinoma (ccRCC). We designed this work to investigate the role of LINC00887 in regulating CD8+ T cell immune infiltration in ccRCC.

Methods

Correlation between LINC00887 and immune factors and the expression level of LINC00887 in ccRCC were analyzed by bioinformatics methods (TCGA-KIRC database, “edgeR” package, “clusterProfiler” package, and “CIBERSORT” package). LINC00887 expression in ccRCC was examined via RT-qPCR. The cytokilling capacity of CD8+ T cells was evaluated by the lactate dehydrogenase assay. The apoptotic ability of CD8+ T cells was measured by flow cytometry. The chemotactic ability of CD8+ T cells was revealed by chemotaxis assay. CXCR3, CXCL9, and CXCL10 levels were assessed by RT-qPCR.

Results

As suggested by bioinformatics analysis, LINC00887 was markedly upregulated in ccRCC patients and associated with expression of immune-suppression molecule, thereby abating the immune infiltration level of CD8+ cells in tumor tissue. As revealed by cellular assay, LINC00887 was upregulated in ccRCC cells, and knockdown of LINC00887 resulted in a decreased PD-L1 expression, increased CD8+ T cell toxicity, decreased apoptotic levels, and enhanced chemotaxis. Moreover, we found that LINC00887 exhibited inhibitory effect on immune infiltration of CD8+ cells in clinical tissues.

Conclusions

The results of this study suggested that LINC00887 promoted ccRCC progression by inhibiting immune infiltration of CD8+ T cells, providing new insights into pathogenesis of ccRCC and suggesting LINC00887 being a promising immunotherapy target for ccRCC.

Integration of the Connectivity Map and Pathway Analysis to Predict Plant Extract’s Medicinal Properties—The Study Case of Sarcopoterium spinosum L

Medicinal properties of plants are usually identified based on knowledge of traditional medicine or using low-throughput screens for specific pharmacological activities. The former is very biased since it requires prior knowledge of plants’ properties, while the latter depends on a specific screening system and will miss medicinal activities not covered by the screen. We sought to enrich our understanding of the biological activities of Sarcopoterium spinosum L. root extract based on transcriptome changes to uncover a plurality of possible pharmacological effects without the need for prior knowledge or functional screening. We integrated Gene Set Enrichment Analysis of the RNAseq data to identify pathways affected by the treatment of cells with the extract and perturbational signatures in the CMAP database to enhance the validity of the results. Activities of signaling pathways were measured using immunoblotting with phospho-specific antibodies. Mitochondrial membrane potential was assessed using JC-1 staining. SARS-CoV-2-induced cell killing was assessed in Vero E6 and A549 cells using an MTT assay. Here, we identified transcriptome changes following exposure of cultured cells to the medicinal plant Sarcopoterium spinosum L. root extract. By integrating algorithms of GSEA and CMAP, we confirmed known anti-cancer activities of the extract and predicted novel biological effects on oxidative phosphorylation and interferon pathways. Experimental validation of these pathways uncovered strong activation of autophagy, including mitophagy, and excellent protection from SARS-CoV-2 infection. Our study shows that gene expression analysis alone is insufficient for predicting biological effects since some of the changes reflect compensatory effects, and additional biochemical tests provide necessary corrections. This study defines the advantages and limitations of transcriptome analysis in predicting the biological and medicinal effects of the Sarcopoterium spinosum L. extract. Such analysis could be used as a general approach for predicting the medicinal properties of plants.

The emerging era of personalized medicine in advanced colorectal cancer

Colorectal cancer (CRC) is a genetically heterogeneous disease with its pathogenesis often driven by varying genetic or epigenetic alterations. This has led to a substantial number of patients developing chemoresistance and treatment failure, resulting in a high mortality rate for advanced disease. Deep molecular analysis has allowed for the discovery of key intestinal signaling pathways which impacts colonic epithelial cell fate, and the integral role of the tumor microenvironment on cancer growth and dissemination. Through transitioning pre-clinical knowledge in research into clinical practice, many potential druggable targets within these pathways have been discovered in the hopes of overcoming the roadblocks encountered by conventional therapies. A personalized approach tailoring treatment according to the histopathological and molecular features of individual tumors can hopefully translate to better patient outcomes, and reduce the rate of recurrence in patients with advanced CRC. Herein, the latest understanding on the molecular science behind CRC tumorigenesis, and the potential treatment targets currently at the forefront of research are summarized.

The role of the Smad2/3/4 signaling pathway in osteogenic differentiation regulation by ClC-3 chloride channels in MC3T3-E1 cells

Background

ClC-3 chloride channels promote osteogenic differentiation. Transforming growth factor-β1 (TGF-β1) and its receptors are closely related to ClC-3 chloride channels, and canonical TGF-β1 signaling is largely mediated by Smad proteins. The current study aimed to explore the role of the Smad2/3/4 signaling pathway in the mechanism by which ClC-3 chloride channels regulate osteogenic differentiation in osteoblasts.

Methods

First, real-time PCR and western blotting were used to detect the expression of Smad and mitogen-activated protein kinase (MAPK) proteins in response to ClC-3 chloride channels. Second, immunocytochemistry, coimmunoprecipitation (Co-IP) and immunofluorescence analyses were conducted to assess formation of the Smad2/3/4 complex and its translocation to the nucleus. Finally, markers of osteogenic differentiation were determined by real-time PCR, western blotting, ALP assays and Alizarin Red S staining.

Results

ClC-3 chloride channels knockdown led to increased expression of Smad2/3 but no significant change in p38 or Erk1/2. Furthermore, ClC-3 chloride channels knockdown resulted in increases in the formation of the Smad2/3/4 complex and its translocation to the nucleus. In contrast, the inhibition of TGF-β1 receptors decreased the expression of Smad2, Smad3, p38, and Erk1/2 and the formation of the Smad2/3/4 complex. Finally, the expression of osteogenesis-related markers were decreased upon ClC-3 and Smad2/3/4 knockdown, but the degree to which these parameters were altered was decreased upon the knockdown of ClC-3 and Smad2/3/4 together compared to independent knockdown of ClC-3 or Smad2/3/4.

Conclusions

The Smad2/3 proteins respond to changes in ClC-3 chloride channels. The Smad2/3/4 signaling pathway inhibits osteogenic differentiation regulation by ClC-3 chloride channels in MC3T3-E1 cells.

Rational design of synthetically tractable HDAC6/HSP90 dual inhibitors to destroy immune-suppressive tumor microenvironment

INTRODUCTION

The tumor microenvironment is mainly flooded with immunosuppressive cells and inhibitory cytokines, resulting in the inability of effective immune cells to infiltrate and recognize tumors and even the loss of anti-cancer ability.

OBJECTIVES

We propose a novel HDAC6/HSP90 dual inhibitory strategy as well as a chemoimmunotherapeutic agent that does not only kill tumor cells but also destroys the tumor microenvironment and enhances anti-cancer immunity.

METHODS

A hybrid scaffold construction approach was leveraged to furnish a series of rationally designed resorcinol-based hydroxamates as dual selective HDAC6/HSP90 inhibitors. The drug design campaign commenced with a fragment recruitment process to pinpoint validated structural units to inhibit HDAC6 and HSP90, followed by their installation in flexible HDAC inhibitory templates via an efficient and facile multistep synthetic route. Subsequent evaluations identified a strikingly potent selective HDAC6/HSP90 dual inhibitor (compound 17) via molecular and biological analysis in vitro and in vivo.

RESULTS

Compound 17 exhibited not only direct cytotoxicity to cancer cells but also downregulated immune checkpoints (PD-L1 and IDO) expression in tumors via the inhibition of STAT1 pathway and degradation of oncogene proteins (Src, AKT, Rb, and FAK), leading to in vivo tumor growth inhibition. These multiple effects enabled the effector T cells to largely infiltrate into the tumor region and release granzyme B to kill cancer cells. In addition, compound 17 also decreased TGF-β secretion from normal cells, resulting in the systemic reduction of immunosuppressive regulatory T cells. Delightfully, a cocktail treatment of compound 17 and anti-PD-1 antibodies demonstrated synergistic efficacy to eliminate solid tumors with 83.9% of tumor growth inhibition.

CONCLUSION

In summary, the impressive activity profile of compound 17, as an effective anticancer agent and a potential immunosensitizer, forecasts the application of HDAC6/HSP90 dual inhibitory strategy to overcome the immunosuppressive tumor microenvironment.

Efficacy of Immune Checkpoint Inhibitor With or Without Chemotherapy for Non–Squamous Non-Small Cell Lung Cancer with Malignant Pleural Effusion: A Retrospective Multicenter Cohort Study

Introduction

Malignant pleural effusion (MPE) is associated with poor treatment outcome in patients with NSCLC receiving immune checkpoint inhibitors (ICIs). ICIs and chemotherapy (ICI/Chemo) combination therapy is currently the standard therapy for NSCLC, and some ICI/Chemo regimens for nonsquamous (non-Sq) NSCLC contain bevacizumab (BEV), which is effective for controlling MPE and may enhance immune response. This study aimed to determine the optimal first-line treatment for this clinical population.

Methods

We retrospectively enrolled consecutive patients with non-Sq NSCLC with MPE who received ICI/Chemo or pembrolizumab monotherapy. Treatment outcomes were analyzed in patients with programmed death-ligand 1 (PD-L1) tumor proportion score more than or equal to 50% who were administered ICI/Chemo or pembrolizumab monotherapy (PD-L1 high cohort) and in patients with any PD-L1 status, treated with ICI/Chemo with or without BEV (ICI/Chemo cohort). We used propensity score matching (PSM) to reduce bias.

Results

PD-L1 high and ICI/Chemo cohorts included 143 and 139 patients, respectively. In PD-L1 high cohort, 37 patients received ICI/Chemo. With PSM, the median progression-free survival was significantly longer in the ICI/Chemo group than in the pembrolizumab group (11.1 versus 3.9 mo, respectively, p = 0.0409). In the ICI/Chemo cohort, 23 patients received BEV. With PSM, no significant difference occurred in median progression-free survival between BEV and non-BEV groups (6.1 versus 7.4 mo, p = 0.9610).

Conclusion

ICI/Chemo seemed more effective than pembrolizumab monotherapy for patients with non-Sq NSCLC with MPE. Nevertheless, the synergistic effect of BEV with ICI/Chemo may be limited. Further studies are needed to clarify the key factor in the tumor-induced immunosuppression environment in these patients.

Tumor in the Crossfire: Inhibiting TGF-β to Enhance Cancer Immunotherapy

Cancer immunotherapy using monoclonal antibodies targeting immune checkpoints has undoubtedly revolutionized the cancer treatment landscape in the last decade. Immune checkpoint inhibitors can elicit long-lasting, previously unheard-of responses in a number of tumor entities. Yet, even in such tumors as metastatic melanoma and non-small cell-lung cancer, in which immune checkpoint inhibition has become the first-line treatment of choice, only a minority of patients will benefit considerably from these treatments. This has been attributed to a number of factors, including an immune-suppressive tumor microenvironment (TME). Using different modalities to break these barriers is of utmost importance to expand the population of patients that benefit from immune checkpoint inhibition. The multifunctional cytokine transforming growth factor-β (TGF-β) has long been recognized as an immune-suppressive factor in the TME. A considerable number of drugs have been developed to target TGF-β, yet most of these have since been discontinued. The combination of anti-TGF-β agents with immune checkpoint inhibitors now has the potential to revive this target as a viable immunomodulatory therapeutic approach. Currently, a limited number of small molecular inhibitor and monoclonal antibody candidates that target TGF-β are in clinical development in combination with the following immune checkpoint inhibitors: SRK 181, an antibody inhibiting the activation of latent TGF-β1; NIS 793, a monoclonal antibody targeting TGF-β; and SHR 1701, a fusion protein consisting of an anti-PD-L1 monoclonal antibody fused with the extracellular domain of human TGF-β receptor II. Several small molecular inhibitors are also in development and are briefly reviewed: LY364947, a pyrazole-based small molecular inhibitor of the serine-threonine kinase activity of TGFβRI; SB-431542, an inhibitor targeting several TGF-β superfamily Type I activin receptor-like kinases as well as TGF-β1-induced nuclear Smad3 localization; and galunisertib, an oral small molecular inhibitor of the TGFβRI kinase. One of the most advanced agents in this area is bintrafusp alfa, a bifunctional fusion protein composed of the extracellular domain of TGF-β receptor II fused to a human IgG1 mAb blocking PD-L1. Bintrafusp alfa is currently in advanced clinical development and as an agent in this space with the most clinical experience, is a focused highlight of this review.

Tumor Microenvironment and Hydrogel-Based 3D Cancer Models for In Vitro Testing Immunotherapies

Simple Summary

Immunotherapies are emerging as promising strategies to cure cancer and extend patients’ survival. Efforts should be focused, however, on the development of preclinical tools better able to predict the therapeutic benefits in individual patients. In this context, the availability of reliable preclinical models capable of recapitulating the tumor milieu while overcoming the limitations of traditional systems is mandatory. Here, we review the tumor immune responses, escape mechanisms, and the most recent 3D biomaterial-based cancer in vitro models useful for investigating the effects of the different immunotherapeutic approaches. The main challenges and possible future trends are also discussed.

Abstract

In recent years, immunotherapy has emerged as a promising novel therapeutic strategy for cancer treatment. In a relevant percentage of patients, however, clinical benefits are lower than expected, pushing researchers to deeply analyze the immune responses against tumors and find more reliable and efficient tools to predict the individual response to therapy. Novel tissue engineering strategies can be adopted to realize in vitro fully humanized matrix-based models, as a compromise between standard two-dimensional (2D) cell cultures and animal tests, which are costly and hardly usable in personalized medicine. In this review, we describe the main mechanisms allowing cancer cells to escape the immune surveillance, which may play a significant role in the failure of immunotherapies. In particular, we discuss the role of the tumor microenvironment (TME) in the establishment of a milieu that greatly favors cancer malignant progression and impact on the interactions with immune cells. Then, we present an overview of the recent in vitro engineered preclinical three-dimensional (3D) models that have been adopted to resemble the interplays between cancer and immune cells and for testing current therapies and immunotherapeutic approaches. Specifically, we focus on 3D hydrogel-based tools based on different types of polymers, discussing the suitability of each of them in reproducing the TME key features based on their intrinsic or tunable characteristics. Finally, we introduce the possibility to combine the 3D models with technological fluid dynamics platforms, reproducing the dynamic complex interactions between tumor cells and immune effectors migrated in situ via the systemic circulation, pointing out the challenges that still have to be overcome for setting more predictive preclinical assays.

Immunotherapy for Colorectal Cancer: Mechanisms and Predictive Biomarkers

Simple Summary

Late-stage colorectal cancer treatment often involves chemotherapy and radiation that can cause dose-limiting toxicity, and therefore there is great interest in developing targeted therapies for this disease. Immunotherapy is a targeted therapy that uses peptides, cells, antibodies, viruses, or small molecules to engage or train the immune system to kill cancer. Here, we discuss the preclinical and clinical development of immunotherapy for treatment of colorectal cancer and provide an overview of predictive biomarkers for such treatments. We also consider open questions including optimal combination treatments and sensitization of colorectal cancer patients with proficient mismatch repair enzymes.

Abstract

Though early-stage colorectal cancer has a high 5 year survival rate of 65–92% depending on the specific stage, this probability drops to 13% after the cancer metastasizes. Frontline treatments for colorectal cancer such as chemotherapy and radiation often produce dose-limiting toxicities in patients and acquired resistance in cancer cells. Additional targeted treatments are needed to improve patient outcomes and quality of life. Immunotherapy involves treatment with peptides, cells, antibodies, viruses, or small molecules to engage or train the immune system to kill cancer cells. Preclinical and clinical investigations of immunotherapy for treatment of colorectal cancer including immune checkpoint blockade, adoptive cell therapy, monoclonal antibodies, oncolytic viruses, anti-cancer vaccines, and immune system modulators have been promising, but demonstrate limitations for patients with proficient mismatch repair enzymes. In this review, we discuss preclinical and clinical studies investigating immunotherapy for treatment of colorectal cancer and predictive biomarkers for response to these treatments. We also consider open questions including optimal combination treatments to maximize efficacy, minimize toxicity, and prevent acquired resistance and approaches to sensitize mismatch repair-proficient patients to immunotherapy.

Immunomodulatory Potential of Non-Classical HLA-G in Infections including COVID-19 and Parasitic Diseases

Human Leukocyte Antigen-G (HLA-G), a polymorphic non-classical HLA (HLA-Ib) with immune-regulatory properties in cancers and infectious diseases, presents both membrane-bound and soluble (sHLA-G) isoforms. Polymorphism has implications in host responses to pathogen infections and in pathogenesis. Differential expression patterns of HLA-G/sHLA-G or its polymorphism seem to be related to different pathological conditions, potentially acting as a disease progression biomarker. Pathogen antigens might be involved in the regulation of both membrane-bound and sHLA-G levels and impact immune responses during co-infections. The upregulation of HLA-G in viral and bacterial infections induce tolerance to infection. Recently, sHLA-G was found useful to identify the prognosis of Coronavirus disease 2019 (COVID-19) among patients and it was observed that the high levels of sHLA-G are associated with worse prognosis. The use of pathogens, such as Plasmodium falciparum, as immune modulators for other infections could be extended for the modulation of membrane-bound HLA-G in COVID-19-infected tissues. Overall, such information might open new avenues concerning the effect of some pathogens such as parasites in decreasing the expression level of HLA-G to restrict pathogenesis in some infections or to influence the immune responses after vaccination among others.

TGF-β and Cancer Immunotherapy

The cytokine, transforming growth factor beta (TGF-β), has a history of more than 40 years. TGF-β is secreted by many tumor cells and is associated with tumor growth and cancer immunity. The canonical TGF-β signaling pathway, SMAD, controls both tumor metastasis and immune regulation, thereby regulating cancer immunity. TGF-β regulates multiple types of immune cells in tumor microenvironment, including T cells, natural killer (NK) cells, and macrophages. One of the main roles of TGF-β in the tumor microenvironment is the generation of regulatory T cells, which contribute to the suppression of anti-tumor immunity. Because cancer is one of the highest causes of death globally, the discovery of immune checkpoint inhibitors by Honjo and Allison in cancer immunotherapy earned a Nobel Prize in 2018. TGF-β also regulates the levels of immune checkpoints inhibitory receptors on immune cells. Immune checkpoints inhibitors are now being developed along with anti-TGF-β antibody and/or TGF-β inhibitors. More recently, chimeric antigen receptors (CARs) were applied to cancer immunity and tried to combine with TGF-β blockers.

(Im)maturity in Tumor Ecosystem

Tumors have special features that make them distinct from their normal counterparts. Immature cells in a tumor mass and their critical contributions to the tumorigenesis will open new windows toward cancer therapy. Incomplete cellular development brings versatile and unique functionality in the cellular tumor ecosystem, such as what is seen for highly potential embryonic cells. There is evidence that maturation of certain types of cells in this ecosystem can recover the sensitivity of the tumor. Therefore, understanding more about the mechanisms that contributed to this immaturity will render new therapeutic approaches in cancer therapy. Targeting such mechanisms can be exploited as a supplementary to the current immunotherapeutic treatment schedules, such as immune checkpoint inhibitor (ICI) therapy. The key focus of this review is to discuss the impact of (im)maturity in cellular tumor ecosystems on cancer progression, focusing mainly on immaturity in the immune cell compartment of the tumor, as well as on the stemness of tumor cells.

Combination strategies with PD-1/PD-L1 blockade: current advances and future directions

Antibodies targeting programmed cell death protein-1 (PD-1) or its ligand PD-L1 rescue T cells from exhausted status and revive immune response against cancer cells. Based on the immense success in clinical trials, ten α-PD-1 (nivolumab, pembrolizumab, cemiplimab, sintilimab, camrelizumab, toripalimab, tislelizumab, zimberelimab, prolgolimab, and dostarlimab) and three α-PD-L1 antibodies (atezolizumab, durvalumab, and avelumab) have been approved for various types of cancers. Nevertheless, the low response rate of α-PD-1/PD-L1 therapy remains to be resolved. For most cancer patients, PD-1/PD-L1 pathway is not the sole speed-limiting factor of antitumor immunity, and it is insufficient to motivate effective antitumor immune response by blocking PD-1/PD-L1 axis. It has been validated that some combination therapies, including α-PD-1/PD-L1 plus chemotherapy, radiotherapy, angiogenesis inhibitors, targeted therapy, other immune checkpoint inhibitors, agonists of the co-stimulatory molecule, stimulator of interferon genes agonists, fecal microbiota transplantation, epigenetic modulators, or metabolic modulators, have superior antitumor efficacies and higher response rates. Moreover, bifunctional or bispecific antibodies containing α-PD-1/PD-L1 moiety also elicited more potent antitumor activity. These combination strategies simultaneously boost multiple processes in cancer-immunity cycle, remove immunosuppressive brakes, and orchestrate an immunosupportive tumor microenvironment. In this review, we summarized the synergistic antitumor efficacies and mechanisms of α-PD-1/PD-L1 in combination with other therapies. Moreover, we focused on the advances of α-PD-1/PD-L1-based immunomodulatory strategies in clinical studies. Given the heterogeneity across patients and cancer types, individualized combination selection could improve the effects of α-PD-1/PD-L1-based immunomodulatory strategies and relieve treatment resistance.