Phase I study of GC1008 (fresolimumab): a human anti-transforming growth factor-beta (TGFβ) monoclonal antibody in patients with advanced malignant melanoma or renal cell carcinoma

Targeting the Myofibroblastic Cancer-Associated Fibroblast Phenotype Through Inhibition of NOX4

Background

Cancer-associated fibroblasts (CAFs) are tumor-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed.

Methods

CAF accumulation and prognostic significance in head and neck cancer (oral, n = 260; oropharyngeal, n = 271), and colorectal cancer (n = 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4's role in CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypic culture assays, and in vivo, using xenograft (n = 9-15 per group) and isograft (n = 6 per group) tumor models. All statistical tests were two-sided.

Results

Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specific survival rates in each cancer type analyzed (hazard ratios [HRs] = 1.69-7.25, 95% confidence intervals [CIs] = 1.11 to 31.30, log-rank P ≤ .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significant upregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic-CAFs (r = 0.65-0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic-CAF phenotype ex vivo (54.3% decrease in α-smooth muscle actin [α-SMA], 95% CI = 10.6% to 80.9%, P = .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%-79.0% decrease in α-SMA across different models, P ≤ .02) and slow tumor growth (30.6%-64.0% decrease across different models, P ≤ .04).

Conclusions

These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types.

Modeling Macrophage Polarization and Its Effect on Cancer Treatment Success

Positive feedback loops drive immune cell polarization toward a pro-tumor phenotype that accentuates immunosuppression and tumor angiogenesis. This phenotypic switch leads to the escape of cancer cells from immune destruction. These positive feedback loops are generated by cytokines such as TGF-β, Interleukin-10 and Interleukin-4, which are responsible for the polarization of monocytes and M1 macrophages into pro-tumor M2 macrophages, and the polarization of naive helper T cells intopro-tumor Th2 cells. In this article, we present a deterministic ordinary differential equation (ODE) model that includes key cellular interactions and cytokine signaling pathways that lead to immune cell polarization in the tumor microenvironment. The model was used to simulate various cancer treatments in silico. We identified combination therapies that consist of M1 macrophages or Th1 helper cells, coupled with an anti-angiogenic treatment, that are robust with respect to immune response strength, initial tumor size and treatment resistance. We also identified IL-4 and IL-10 as the targets that should be neutralized in order to make these combination treatments robust with respect to immune cell polarization. The model simulations confirmed a hypothesis based on published experimental evidence that a polarization into the M1 and Th1 phenotypes to increase the M1-to-M2 and Th1-to-Th2 ratios plays a significant role in treatment success. Our results highlight the importance of immune cell reprogramming as a viable strategy to eradicate a highly vascularized tumor when the strength of the immune response is characteristically weak and cell polarization to the pro-tumor phenotype has occurred.

The clinical and biological roles of transforming growth factor beta in colon cancer stem cells: A systematic review

BACKGROUND

Transforming growth factor beta (TGF-β) is a multipurpose cytokine, which plays a role in many cellular functions such as proliferation, differentiation, migration, apoptosis, cell adhesion and regulation of epithelial to mesenchymal transition. Despite many studies having observed the effect that TGF-β plays in colorectal cancer, its role in the colorectal stem cell population has not been widely observed.

METHOD

This systematic review will analyse the role of TGF-β in the stem cell population of colorectal cancer.

RESULTS

The effects on the stem cell phenotype are through the downstream proteins involved in activation of the TGF-β pathway. Its involvement in the initiation of the epithelial to mesenchymal transition (EMT), the effect of colorectal invasion and metastasis regulated through the Smad protein involvement in the EMT, initiation of angiogenesis, promotion of metastasis of colorectal cancer to the liver and its ability to cross-talk with other pathways.

CONCLUSION

TGF-β is a key player in angiogenesis, tumour growth and metastasis in colon cancer.

The molecular biology of pelvi-ureteric junction obstruction

Over recent years routine ultrasound scanning has identified increasing numbers of neonates as having hydronephrosis and pelvi-ureteric junction obstruction (PUJO). This patient group presents a diagnostic and management challenge for paediatric nephrologists and urologists. In this review we consider the known molecular mechanisms underpinning PUJO and review the potential of utilising this information to develop novel therapeutics and diagnostic biomarkers to improve the care of children with this disorder.

How Signaling Molecules Regulate Tumor Microenvironment: Parallels to Wound Repair

It is now suggested that the inhibition of biological programs that are associated with the tumor microenvironment may be critical to the diagnostics, prevention and treatment of cancer. On the other hand, a suitable wound microenvironment would accelerate tissue repair and prevent extensive scar formation. In the present review paper, we define key signaling molecules (growth factors, cytokines, chemokines, and galectins) involved in the formation of the tumor microenvironment that decrease overall survival and increase drug resistance in cancer suffering patients. Additional attention will also be given to show whether targeted modulation of these regulators promote tissue regeneration and wound management. Whole-genome transcriptome profiling, in vitro and animal experiments revealed that interleukin 6, interleukin 8, chemokine (C-X-C motif) ligand 1, galectin-1, and selected proteins of the extracellular matrix (e.g., fibronectin) do have similar regulation during wound healing and tumor growth. Published data demonstrate remarkable similarities between the tumor and wound microenvironments. Therefore, tailor made manipulation of cancer stroma can have important therapeutic consequences. Moreover, better understanding of cancer cell-stroma interaction can help to improve wound healing by supporting granulation tissue formation and process of reepithelization of extensive and chronic wounds as well as prevention of hypertrophic scars and formation of keloids.

Targeting TGF-β Signaling for Therapeutic Gain

Transforming growth factor βs (TGF-βs) are closely related ligands that have pleiotropic activity on most cell types of the body. They act through common heterotetrameric TGF-β type II and type I transmembrane dual specificity kinase receptor complexes, and the outcome of signaling is context-dependent. In normal tissue, they serve a role in maintaining homeostasis. In many diseased states, particularly fibrosis and cancer, TGF-β ligands are overexpressed and the outcome of signaling is diverted toward disease progression. There has therefore been a concerted effort to develop drugs that block TGF-β signaling for therapeutic benefit. This review will cover the basics of TGF-β signaling and its biological activities relevant to oncology, present a summary of pharmacological TGF-β blockade strategies, and give an update on preclinical and clinical trials for TGF-β blockade in a variety of solid tumor types.

Targeting TGF-β Signaling for Therapeutic Gain

Transforming growth factor βs (TGF-βs) are closely related ligands that have pleiotropic activity on most cell types of the body. They act through common heterotetrameric TGF-β type II and type I transmembrane dual specificity kinase receptor complexes, and the outcome of signaling is context-dependent. In normal tissue, they serve a role in maintaining homeostasis. In many diseased states, particularly fibrosis and cancer, TGF-β ligands are overexpressed and the outcome of signaling is diverted toward disease progression. There has therefore been a concerted effort to develop drugs that block TGF-β signaling for therapeutic benefit. This review will cover the basics of TGF-β signaling and its biological activities relevant to oncology, present a summary of pharmacological TGF-β blockade strategies, and give an update on preclinical and clinical trials for TGF-β blockade in a variety of solid tumor types.

Tumor immunoevasion by the conversion of effector NK cells into type 1 innate lymphoid cells

Avoiding destruction by immune cells is a hallmark of cancer, yet how tumors ultimately evade control by natural killer (NK) cells remains incompletely defined. Using global transcriptomic and flow-cytometry analyses and genetically engineered mouse models, we identified the cytokine-TGF-β-signaling-dependent conversion of NK cells (CD49a-CD49b+Eomes+) into intermediate type 1 innate lymphoid cell (intILC1) (CD49a+CD49b+Eomes+) populations and ILC1 (CD49a+CD49b-Eomesint) populations in the tumor microenvironment. Strikingly, intILC1s and ILC1s were unable to control local tumor growth and metastasis, whereas NK cells favored tumor immunosurveillance. Experiments with an antibody that neutralizes the cytokine TNF suggested that escape from the innate immune system was partially mediated by TNF-producing ILC1s. Our findings provide new insight into the plasticity of group 1 ILCs in the tumor microenvironment and suggest that the TGF-β-driven conversion of NK cells into ILC1s is a previously unknown mechanism by which tumors escape surveillance by the innate immune system.

EMT: Mechanisms and therapeutic implications

Metastasis, the dissemination of cancer cells from primary tumors, represents a major hurdle in the treatment of cancer. The epithelial-mesenchymal transition (EMT) has been studied in normal mammalian development for decades, and it has been proposed as a critical mechanism during cancer progression and metastasis. EMT is tightly regulated by several internal and external cues that orchestrate the shifting from an epithelial-like phenotype into a mesenchymal phenotype, relying on a delicate balance between these two stages to promote metastatic development. EMT is thought to be induced in a subset of metastatic cancer stem cells (MCSCs), bestowing this population with the ability to spread throughout the body and contributing to therapy resistance. The EMT pathway is of increasing interest as a novel therapeutic avenue in the treatment of cancer, and could be targeted to prevent tumor cell dissemination in early stage patients or to eradicate existing metastatic cells in advanced stages. In this review, we describe the sequence of events and defining mechanisms that take place during EMT, and how these interactions drive cancer cell progression into metastasis. We summarize clinical interventions focused on targeting various aspects of EMT and their contribution to preventing cancer dissemination.

Polaprezinc inhibits liver fibrosis and proliferation in hepatocellular carcinoma

Hepatic fibrosis is defined as a pathological process, and activation of hepatic stellate cells (HSCs) is believed to be the key event of liver fibrosis. Additionally, activated HSCs may participate in the formation of the tumor microenvironment. Polaprezinc, a protector of the gastric mucosa, has been recently demonstrated to be an inhibitor of liver fibrosis in a mouse model. Proliferation and colony formation assays were performed to determine the inhibitory effects of polaprezinc on the growth of LX‑2 and hepG2 cells. A migration assay was used to evaluate the change in mobility of LX‑2 cells and quantitative polymerase chain reaction was performed to detect the expression levels of key markers of fibrosis. Finally, a gene chip assay for polaprezinc‑treated hepG2 cells was performed to evaluate the effect of polaprezinc on the hepG2 gene expression profile. The proliferation assay indicated that polaprezinc may inhibit the LX‑2 cell proliferation and the migration assays confirmed the inhibition of mobility. The expression levels of fibrotic markers such as collagen I, fibronectin and α‑smooth muscle actin were downregulated following polaprezinc treatment. The proliferation activity of polaprezinc‑treated hepG2 cells was reduced and the gene chip assay indicated that series of gene expression changes associated with cancer migration, cell skeletal organization and proliferation had occurred. In conclusion, polaprezinc treatment mayinhibit the proliferation of hepatocellular carcinoma cells and reverse liver fibrosis by deactivating HSCs. The present findings suggest that polaprezinc provides a novel treatment for patients with gastritis complicated with cirrhosis.

Cancer Immunotherapy: Historical Perspective of a Clinical Revolution and Emerging Preclinical Animal Models

At the turn of the last century, the emerging field of medical oncology chose a cytotoxic approach to cancer therapy over an immune-centered approach at a time when evidence in support of either paradigm did not yet exist. Today, nearly 120 years of data have established that (a) even the best cytotoxic regimens only infrequently cure late-stage malignancy and (b) strategies that supplement and augment existing antitumor immune responses offer the greatest opportunities to potentiate durable remission in cancer. Despite widespread acceptance of these paradigms today, the ability of the immune system to recognize and fight cancer was a highly controversial topic for much of the twentieth century. Why this modern paradigmatic mainstay should have been both dubious and controversial for such an extended period is a topic of considerable interest that merits candid discussion. Herein, we review the literature to identify and describe the watershed events that ultimately led to the acceptance of immunotherapy as a viable regimen for the treatment of neoplastic malignancy. In addition to noting important clinical discoveries, we also focus on research milestones and the development of critical model systems in rodents and dogs including the advanced modeling techniques that allowed development of patient-derived xenografts. Together, their use will further our understanding of cancer biology and tumor immunology, allow for a speedier assessment of the efficacy and safety of novel approaches, and ultimately provide a faster bench to beside transition.

Effect of cancer-associated fibroblasts on radiosensitivity of cancer cells

Solid tumors are composed of tumor epithelial cells and the stroma, which are seemingly separate but actually related through cell-cell and cell-matrix interactions. These interactions can promote tumor evolution. Cancer-associated fibroblasts (CAFs) are the most abundant non-neoplastic cells in the stroma and also among the most important cell types interacting with cancer cells. Particularly, cancer cells promote the formation and maintenance of CAFs by secreting various cytokines. The activated CAFs then synthesize a series of growth factors to promote tumor cell growth, invasion and metastasis. More importantly, the presence of CAFs also interferes with therapeutic efficacy, bringing severe challenges to radiotherapy. This review summarizes the effect of CAFs on the radiosensitivity of tumor cells and underscores the need for further studies on CAFs in order to improve the efficacy of antitumor therapy.

Epithelial-to-Mesenchymal Transition in the Pathogenesis and Therapy of Head and Neck Cancer

Head and neck cancer (HNC) is one of the most prevalent human malignancies worldwide, with a high morbidity and mortality. Implementation of interdisciplinary treatment modalities has improved the quality of life, but only minor changes in overall survival have been achieved over the past decades. Main causes for treatment failure are an aggressive and invasive tumor growth in combination with a high degree of intrinsic or acquired treatment resistance. A subset of tumor cells gain these properties during malignant progression by reactivating a complex program of epithelia-to-mesenchymal transition (EMT), which is integral in embryonic development, wound healing, and stem cell behavior. EMT is mediated by a core set of key transcription factors, which are under the control of a large range of developmental signals and extracellular cues. Unraveling molecular principles that drive EMT provides new concepts to better understand tumor cell plasticity and response to established as well as new treatment modalities, and has the potential to identify new drug targets for a more effective, less toxic, and individualized therapy of HNC patients. Here, we review the most recent findings on the clinical relevance of a mesenchymal-like phenotype for HNC patients, including more rare cases of mucosal melanoma and adenoid cystic carcinoma.

Zoledronic acid inhibits NFAT and IL-2 signaling pathways in regulatory T cells and diminishes their suppressive function in patients with metastatic cancer

Regulatory T cells (Treg) suppress anti-tumor immune responses and their infiltration in the tumor microenvironment is associated with inferior prognosis in cancer patients. Thus, in order to enhance anti-tumor immune responses, selective depletion of Treg is highly desired. We found that treatment with zoledronic acid (ZA) resulted in a selective decrease in the frequency of Treg that was associated with a significant increase in proliferation of T cells and natural killer (NK) cells in peripheral blood of patients with metastatic cancer. In vitro, genome-wide transcriptomic analysis revealed alterations in calcium signaling pathways in Treg following treatment with ZA. Furthermore, co-localization of the nuclear factor of activated T cells (NFAT) and forkhead box P3 (FOXP3) was significantly reduced in Treg upon ZA-treatment. Consequently, reduced expression levels of CD25, STAT5 and TGFβ were observed. Functionally, ZA-treated Treg had reduced capacity to suppress T and NK cell proliferation and anti-tumor responses compared with untreated Treg in vitro. Treatment with ZA to selectively inhibit essential signaling pathways in Treg resulting in reduced capacity to suppress effector T and NK cell responses represents a novel approach to inhibit Treg activity in patients with cancer.

Transforming growth factor-β: A therapeutic target for cancer

Transforming growth factor-β (TGF-β) regulates cell growth and differentiation, apoptosis, cell motility, extracellular matrix production, angiogenesis, and cellular immunity. It has a paradoxical role in cancer. In the early stages it inhibits cellular transformation and prevents cancer progression. In later stages TGF-β plays a key role in promoting tumor progression through mainly 3 mechanisms: facilitating epithelial to mesenchymal transition, stimulating angiogenesis and inducing immunosuppression. As a result of its opposing tumor promoting and tumor suppressive abilities, TGF-β and its pathway has represented potential opportunities for drug development and several therapies targeting the TGF-β pathway have been identified. This review focuses on identifying the mechanisms through which TGF-β is involved in tumorigenesis and current therapeutics that are under development.

Shifting paradigm of developing biologics for the treatment of pancreatic adenocarcinoma

Pancreatic adenocarcinoma is still widely considered as a deadly disease even though there are substantial therapeutic developments in the past decade. Using combinational chemotherapy regimens, represented by gemcitabine plus nab-paclitaxel and FOLFIRINOX, was able to improve overall survival in patients with advanced disease to a limited extent. It has been a challenge to develop targeted therapies that are focused on the neoplasm cells of pancreatic adenocarcinoma. Recently, targeting the stroma and immune compartments of pancreatic adenocarcinoma has shown promising results. The paradigm of biologics drug development therefore has been shifted by extending to these exciting areas. Although some of the preclinical and clinical researches in targeting the tumor microenvironment of pancreatic adenocarcinoma have shown promising results, others have resulted in controversial findings. Both comprehensive and in-depth researches on the basic science of the tumor microenvironment of pancreatic adenocarcinoma are thus warranted for the development of effective biologics that target the tumor microenvironment. Moreover, an ideal treatment for pancreatic adenocarcinoma shall be a combination of targeting both neoplastic cells and the tumor microenvironment.

Chinese medicine Bu-Fei decoction attenuates epithelial-mesenchymal transition of non-small cell lung cancer via inhibition of transforming growth factor β1 signaling pathway in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Bu-Fei decoction (BFD) has been utilized to treat patients with Qi deficiency for decades, with the advantages of invigorating vital energy, clearing heat-toxin and moistening lung, etc. According to previous clinical experience and trials, BFD has been found to indeed improve life quality of lung cancer patients and prolong survival time. Nevertheless, little is known on its potential mechanisms so far. Being regarded as a pivotal cytokine in the tumor microenvironment, transforming growth factor β (TGF-β) stands out as a robust regulator of epithelial-mesenchymal transition (EMT), which is closely linked to tumor progression.

AIM OF THE STUDY

The present study was designed to explore whether BFD antagonized EMT via blocking TGF-β1-induced signaling pathway, and then help contribute to create a relatively steady microenvironment for confining lung cancer.

MATERIALS AND METHODS

This experiment was performed in lung adenocarcinoma A549 cells both in vitro and in vivo. In detail, the influences mediated by TGF-β1 alone or in combination with different concentrations of BFD on migration were detected by wound healing and transwell assays, and the effects of BFD on cell viability were determined by cell counting kit-8 (CCK-8) assay. TGF-β1, EMT relevant proteins and genes were evaluated by western blotting, confocal microscopy, quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC) and enzyme-linked immuno sorbent assay (ELISA). Female BALB/C nude mice were subcutaneously implanted A549 cells and given BFD by gavage twice daily for 28 days. The tumor volume was monitored every 4 days to draw growth curve. The tumor weight, expression levels of EMT-related protein in tumor tissues and TGF-β1 serum level were evaluated, respectively.

RESULTS

BFD only exerted minor effects on A549 cell proliferation and this was in accordance with the in vivo result, which showed that the tumor growth and weight were not be restrained by BFD administration. However, the data elucidated that BFD could dose-dependently suppress EMT induced by TGF-β1 in vitro via attenuating canonical Smad signaling pathway. In the A549 xenograft mouse model, BFD also inhibited protein markers that are associated with EMT and TGF-β1 secretion into serum.

CONCLUSIONS

Based on these above data, the conclusion could be put forward that BFD probably attenuated TGF-β1 mediated EMT in A549 cells via decreasing canonical Smad signaling pathway both in vitro and in vivo, which may help restrain the malignant phenotype induced by TGF-β1 in A549 cells to some extent.

The predictive value of transforming growth factor-β in Wilms tumor immunopathogenesis

Wilms tumor is the most common kidney malignancy in children, especially in children aged less than 6 years. Although therapeutic approach has reached successful rates, there is still room for improvement. Considering the tumor microenvironment, cytokines represent important elements of interaction and communication between tumor cells, stroma, and immune cells. In this regard, the transforming growth factor beta (TGF-β) family members play significant functions in physiological and pathological conditions, particularly in cancer. By regulating cell growth, death, and immortalization, TGF-β signaling pathways exert tumor suppressor effects in normal and early tumor cells. Thus, it is not surprising that a high number of human tumors arise due to alterations in genes coding for various TGF-β signaling components. Understanding the ambiguous role of TGF-β in human cancer is of paramount importance for the development of new therapeutic strategies to specifically block the metastatic signaling pathway of TGF-β without affecting its tumor suppressive effect. In this context, this review attempt to summarize the involvement of TGF-β in Wilms tumor.

Prospects for combining targeted and conventional cancer therapy with immunotherapy

Over the past 25 years, research in cancer therapeutics has largely focused on two distinct lines of enquiry. In one approach, efforts to understand the underlying cell-autonomous, genetic drivers of tumorigenesis have led to the development of clinically important targeted agents that result in profound, but often not durable, tumour responses in genetically defined patient populations. In the second parallel approach, exploration of the mechanisms of protective tumour immunity has provided several therapeutic strategies - most notably the 'immune checkpoint' antibodies that reverse the negative regulators of T cell function - that accomplish durable clinical responses in subsets of patients with various tumour types. The integration of these potentially complementary research fields provides new opportunities to improve cancer treatments. Targeted and immune-based therapies have already transformed the standard-of-care for several malignancies. However, additional insights into the effects of targeted therapies, along with conventional chemotherapy and radiation therapy, on the induction of antitumour immunity will help to advance the design of combination strategies that increase the rate of complete and durable clinical response in patients.

Integrin β1 activation induces an anti-melanoma host response

TGF-β is a cytokine thought to function as a tumor promoter in advanced malignancies. In this setting, TGF-β increases cancer cell proliferation, survival, and migration, and orchestrates complex, pro-tumorigenic changes in the tumor microenvironment. Here, we find that in melanoma, integrin β1-mediated TGF-β activation may also produce tumor suppression via an altered host response. In the A375 human melanoma cell nu/nu xenograft model, we demonstrate that cell surface integrin β1-activation increases TGF-β activity, resulting in stromal activation, neo-angiogenesis and, unexpectedly for this nude mouse model, increase in the number of intra-tumoral CD8⁺ T lymphocytes within the tumor microenvironment. This is associated with attenuation of tumor growth and long-term survival benefit. Correspondingly, in human melanomas, TGF-β1 correlates with integrin β1/TGF-β1 activation and the expression of markers for vasculature and stromal activation. Surprisingly, this integrin β1/TGF-β1 transcriptional footprint also correlates with the expression of markers for tumor-infiltrating lymphocytes, multiple immune checkpoints and regulatory pathways, and, importantly, better long-term survival of patients. These correlations are unique to melanoma, in that we do not observe similar associations between β1 integrin/TGF-β1 activation and better long-term survival in other human tumor types. These results suggest that activation of TGF-β1 in melanoma may be associated with the generation of an anti-tumor host response that warrants further study.

Blockade of only TGF-β 1 and 2 is sufficient to enhance the efficacy of vaccine and PD-1 checkpoint blockade immunotherapy

Checkpoint inhibition has established immunotherapy as a major modality of cancer treatment. However, the success of cancer immunotherapy is still limited as immune regulation of tumor immunity is very complicated and mechanisms involved may also differ among cancer types. Beside checkpoints, other good candidates for immunotherapy are immunosuppressive cytokines. TGF-β is a very potent immunosuppressive cytokine involved in suppression of tumor immunity and also necessary for the function of some regulatory cells. TGF-β has three isoforms, TGF-β 1, 2 and 3. It has been demonstrated in multiple mouse tumor models that inhibition of all three isoforms of TGF-β facilitates natural tumor immunosurveillance and tumor vaccine efficacy. However, individual isoforms of TGF-β are not well studied yet. Here, by using monoclonal antibodies (mAbs) specific for TGF-β isoforms, we asked whether it is necessary to inhibit TGF-β3 to enhance tumor immunity. We found that blockade of TGF-β1 and 2 and of all isoforms provided similar effects on tumor natural immunosurveillance and therapeutic vaccine-induced tumor immunity. The protection was CD8⁺ T cell-dependent. Blockade of TGF-β increased vaccine-induced Th1-type response measured by IFNγ production or T-bet expression in both tumor draining lymph nodes and tumors, although it did not increase tumor antigen-specific CD8⁺ T cell numbers. Therefore, protection correlated with qualitative rather than quantitative changes in T cells. Furthermore, when combined with PD-1 blockade, blockade of TGF-β1 and 2 further increased vaccine efficacy. In conclusion, blocking TGF-β1 and 2 is sufficient to enhance tumor immunity, and it can be further enhanced with PD-1 blockade.

Barriers to Radiation-Induced In Situ Tumor Vaccination

The immunostimulatory properties of radiation therapy (RT) have recently generated widespread interest due to preclinical and clinical evidence that tumor-localized RT can sometimes induce antitumor immune responses mediating regression of non-irradiated metastases (abscopal effect). The ability of RT to activate antitumor T cells explains the synergy of RT with immune checkpoint inhibitors, which has been well documented in mouse tumor models and is supported by observations of more frequent abscopal responses in patients refractory to immunotherapy who receive RT during immunotherapy. However, abscopal responses following RT remain relatively rare in the clinic, and antitumor immune responses are not effectively induced by RT against poorly immunogenic mouse tumors. This suggests that in order to improve the pro-immunogenic effects of RT, it is necessary to identify and overcome the barriers that pre-exist and/or are induced by RT in the tumor microenvironment. On the one hand, RT induces an immunogenic death of cancer cells associated with release of powerful danger signals that are essential to recruit and activate dendritic cells (DCs) and initiate antitumor immune responses. On the other hand, RT can promote the generation of immunosuppressive mediators that hinder DCs activation and impair the function of effector T cells. In this review, we discuss current evidence that several inhibitory pathways are induced and modulated in irradiated tumors. In particular, we will focus on factors that regulate and limit radiation-induced immunogenicity and emphasize current research on actionable targets that could increase the effectiveness of radiation-induced in situ tumor vaccination.

Biomarkers and Immunotherapeutic Targets in Glioblastoma

Glioblastoma (GBM) is an aggressive central nervous system cancer with poor prognosis despite maximal therapy. The recent advent of immunotherapy holds great promise for improving GBM survival and has already made great strides toward changing management strategies. A diverse set of biomarkers have been implicated as immunotherapeutic targets and prognostic indicators in other cancers. Some of the more extensively studied examples include cytokines (IL-4, IL-13, and TGF-β), checkpoint molecules (PD-1, CTLA-4, TIM-3, LAG-3, CD137, GITR, OX40), and growth/angiogenesis proteins (endoglin and EGFR). Emerging theories involving the tumor mutational landscape and microbiome have also been explored in relation to cancer treatment. Although identification of novel biomarkers may improve and help direct treatment of patients with GBM, the next step is to explore the role of biomarkers in precision medicine and selection of specific immunotherapeutic drugs in an individualized manner.

Radiotherapy in the age of cancer immunology: Current concepts and future developments

Major advances in the knowledge of cancer biology and its interactions with tumor immune environment led to the emergence, in the last five years of new immunotherapy-based treatment strategies in cancer patients. At the same time, improvement in radiation technique and progress in radiobiology allowed in the last decade to expand the applications of radiotherapy in a growing number of settings. At present, there are strong theoretical basis to propose immune-enhanced radiation therapy that may represent in the future a new paradigm of treatment, combining the intrinsic power of radiotherapy to elicit a specific, systemic, tumor-directed immune response with modern highly conformal and precise dose delivery, in order to maximize response at the major site of disease and obtain durable disease control. The aim of this review is to describe the principal mechanisms of immune modulation of response to radiation and investigational strategies to harness the potential of radiation-inducible immune response: radiation therapy is expected to be not just a local treatment but the cornerstone of a multimodal strategy that might achieve long-lasting tumor remission at the primary site and systemic efficacy metastatic lesions.

TGFΒ-induced transcription in cancer

The Transforming Growth Factor-beta (TGFβ) pathway mediates a broad spectrum of cellular processes and is involved in several diseases, including cancer. TGFβ has a dual role in tumours, acting as a tumour suppressor in the early phase of tumorigenesis and as a tumour promoter in more advanced stages. In this review, we discuss the effects of TGFβ-driven transcription on all stages of tumour progression, with special focus on lung cancer. Since some TGFβ target genes are specifically involved in promoting metastasis, we speculate that these genes might be good targets to block tumour progression without compromising the tumour suppressor effects of the TGFβ pathway.

Beyond checkpoint inhibition - Immunotherapeutical strategies in combination with radiation

The revival of cancer immunotherapy has taken place with the clinical success of immune checkpoint inhibition. However, the spectrum of immunotherapeutic approaches is much broader encompassing T cell engaging strategies, tumour-specific vaccination, antibodies or immunocytokines. This review focuses on the immunological effects of irradiation and the evidence available on combination strategies with immunotherapy. The available data suggest great potential of combined treatments, yet also poses questions about dose, fractionation, timing and most promising multimodal strategies.

TGF-β Signaling in Gastrointestinal Cancers: Progress in Basic and Clinical Research

Transforming growth factor (TGF)-β superfamily proteins have many important biological functions, including regulation of tissue differentiation, cell proliferation, and migration in both normal and cancer cells. Many studies have reported that TGF-β signaling is associated with disease progression and therapeutic resistance in several cancers. Similarly, TGF-β-induced protein (TGFBI)—a downstream component of the TGF-β signaling pathway—has been shown to promote and/or inhibit cancer. Here, we review the state of basic and clinical research on the roles of TGF-β and TGFBI in gastrointestinal cancers.

Liver inflammation and fibrosis

Chronic liver inflammation leads to fibrosis and cirrhosis, which is the 12th leading cause of death in the United States. Hepatocyte steatosis is a component of metabolic syndrome and insulin resistance. Hepatic steatosis may be benign or progress to hepatocyte injury and the initiation of inflammation, which activates immune cells. While Kupffer cells are the resident macrophage in the liver, inflammatory cells such as infiltrating macrophages, T lymphocytes, neutrophils, and DCs all contribute to liver inflammation. The inflammatory cells activate hepatic stellate cells, which are the major source of myofibroblasts in the liver. Here we review the initiation of inflammation in the liver, the liver inflammatory cells, and their crosstalk with myofibroblasts.

Targeting TGF-β Signaling in Cancer

The transforming growth factor (TGF)-β signaling pathway is deregulated in many diseases, including cancer. In healthy cells and early-stage cancer cells, this pathway has tumor-suppressor functions, including cell-cycle arrest and apoptosis. However, its activation in late-stage cancer can promote tumorigenesis, including metastasis and chemoresistance. The dual function and pleiotropic nature of TGF-β signaling make it a challenging target and imply the need for careful therapeutic dosing of TGF-β drugs and patient selection. We review here the rationale for targeting TGF-β signaling in cancer and summarize the clinical status of pharmacological inhibitors. We discuss the direct effects of TGF-β signaling blockade on tumor and stromal cells, as well as biomarkers that can predict the efficacy of TGF-β inhibitors in cancer patients.

Transforming Growth Factor β Superfamily Signaling in Development of Colorectal Cancer

Transforming growth factor (TGF)-β cytokines signal via a complex network of pathways to regulate proliferation, differentiation, adhesion, migration, and other functions in many cell types. A high percentage of colorectal tumors contain mutations that disrupt TGF-β family member signaling. We review how TGF-β family member signaling is altered during development of colorectal cancer, models of study, interaction of pathways, and potential therapeutic strategies.

The role of the immune system in neurofibromatosis type 1-associated nervous system tumors

With the recent development of new anticancer therapies targeting the immune system, it is important to understand which immune cell types and cytokines play critical roles in suppressing or promoting tumorigenesis. The role of mast cells in promoting neurofibroma growth in neurofibromatosis type 1 (NF1) patients was hypothesized decades ago. More recent experiments in mouse models have demonstrated the causal role of mast cells in neurofibroma development and of microglia in optic pathway glioma development. We review here what is known about the role of NF1 mutation in immune cell function and the role of immune cells in promoting tumorigenesis in NF1. We also review the therapies targeting immune cell pathways and their promise in NF1 tumors.

Pharmacological and immunological targeting of tumor mesenchymalization

Controlling the spread of carcinoma cells to distant organs is the foremost challenge in cancer treatment, as metastatic disease is generally resistant to therapy and is ultimately incurable for the majority of patients. The plasticity of tumor cell phenotype, in which the behaviors and functions of individual tumor cells differ markedly depending upon intrinsic and extrinsic factors, is now known to be a central mechanism in cancer progression. Our expanding knowledge of epithelial and mesenchymal phenotypic states in tumor cells, and the dynamic nature of the transitions between these phenotypes has created new opportunities to intervene to better control the behavior of tumor cells. There are now a variety of innovative pharmacological approaches to preferentially target tumor cells that have acquired mesenchymal features, including cytotoxic agents that directly kill these cells, and inhibitors that block or revert the process of mesenchymalization. Furthermore, novel immunological strategies have been developed to engage the immune system in seeking out and destroying mesenchymalized tumor cells. This review highlights the relevance of phenotypic plasticity in tumor biology, and discusses recently developed pharmacological and immunological means of targeting this phenomenon.

TGF-β Signaling in Bone Remodeling and Osteosarcoma Progression

Osteosarcomas are the most prevalent malignant primary bone tumors in children. Despite intensive efforts to improve both chemotherapeutics and surgical management, 40% of all osteosarcoma patients succumb to the disease. Specifically, the clinical outcome for metastatic osteosarcoma remains poor; less than 30% of patients who present metastases will survive five years after initial diagnosis. Treating metastatic osteosarcoma thus remains a challenge. One of the main characteristics of osteosarcomas is their ability to deregulate bone remodelling. The invasion of bone tissue by tumor cells indeed affects the balance between bone resorption and bone formation. This deregulation induces the release of cytokines or growth factors initially trapped in the bone matrix, such as transforming growth factor-β (TGF-β), which in turn promote tumor progression. Over the past years, there has been considerable interest in the TGF-β pathway within the cancer research community. This review discusses the involvement of the TGF-β signalling pathway in osteosarcoma development and in their metastatic progression.

Downregulation of sphingosine kinase-1 induces protective tumor immunity by promoting M1 macrophage response in melanoma

The infiltration of melanoma tumors by macrophages is often correlated with poor prognosis. However, the molecular signals that regulate the dialogue between malignant cells and the inflammatory microenvironment remain poorly understood. We previously reported an increased expression of sphingosine kinase-1 (SK1), which produces the bioactive lipid sphingosine 1-phosphate (S1P), in melanoma. The present study aimed at defining the role of tumor SK1 in the recruitment and differentiation of macrophages in melanoma. Herein, we show that downregulation of SK1 in melanoma cells causes a reduction in the percentage of CD206highMHCIIlow M2 macrophages in favor of an increased proportion of CD206lowMHCIIhigh M1 macrophages into the tumor. This macrophage differentiation orchestrates T lymphocyte recruitment as well as tumor rejection through the expression of Th1 cytokines and chemokines. In vitro experiments indicated that macrophage migration is triggered by the binding of tumor S1P to S1PR1 receptors present on macrophages whereas macrophage differentiation is stimulated by SK1-induced secretion of TGF-β1. Finally, RNA-seq analysis of human melanoma tumors revealed a positive correlation between SK1 and TGF-β1 expression. Altogether, our findings demonstrate that melanoma SK1 plays a key role in the recruitment and phenotypic shift of the tumor macrophages that promote melanoma growth.

Approaches for targeting cancer stem cells drug resistance

INTRODUCTION

Several reports have suggested that a population of undifferentiated cells known as cancer stem cells (CSCs), is responsible for cancer formation and maintenance. In the last decade, the presence of CSCs in solid cancers have been reported. Areas covered: This review summarizes the main approaches for targeting CSCs drug resistance. It is indeed known that CSCs may contribute to resistance to conventional chemotherapy, radiotherapy and targeted agents. Among the mechanisms by which CSCs escape anticancer therapies, removal of therapeutic agents by drug efflux pumps, enhanced DNA damage repair, activation of mitogenic/anti-apoptotic pathways; the main features of CSCs, stemness and EMT, are involved, as well as the capability to evade immune response. Expert opinion: Different approaches are suitable to target CSCs mediated drug resistance. Some of them are currently under clinical evaluation in different cancer types. A better understanding of CSC biology, as well as more accurate study design, may maximize the therapeutic effects of these agents. In this respect, it is important to establish: (i) which molecules should be targeted; (ii) what drug combinations may be suitable; (iii) which patient settings will CSC targeting offer the highest clinical benefit; and (iv) how to integrate therapeutic approaches targeting CSCs with standard cancer therapy.

Combined treatment with a transforming growth factor beta inhibitor (1D11) and bortezomib improves bone architecture in a mouse model of myeloma-induced bone disease

Multiple myeloma (MM) patients frequently develop tumor-induced bone destruction, yet no therapy completely eliminates the tumor or fully reverses bone loss. Transforming growth factor-β (TGF-β) activity often contributes to tumor-induced bone disease, and pre-clinical studies have indicated that TGF-β inhibition improves bone volume and reduces tumor growth in bone metastatic breast cancer. We hypothesized that inhibition of TGF-β signaling also reduces tumor growth, increases bone volume, and improves vertebral body strength in MM-bearing mice. We treated myeloma tumor-bearing (immunocompetent KaLwRij and immunocompromised Rag2-/-) mice with a TGF-β inhibitory (1D11) or control (13C4) antibody, with or without the anti-myeloma drug bortezomib, for 4weeks after inoculation of murine 5TGM1 MM cells. TGF-β inhibition increased trabecular bone volume, improved trabecular architecture, increased tissue mineral density of the trabeculae as assessed by ex vivo micro-computed tomography, and was associated with significantly greater vertebral body strength in biomechanical compression tests. Serum monoclonal paraprotein titers and spleen weights showed that 1D11 monotherapy did not reduce overall MM tumor burden. Combination therapy with 1D11 and bortezomib increased vertebral body strength, reduced tumor burden, and reduced cortical lesions in the femoral metaphysis, although it did not significantly improve cortical bone strength in three-point bending tests of the mid-shaft femur. Overall, our data provides rationale for evaluating inhibition of TGF-β signaling in combination with existing anti-myeloma agents as a potential therapeutic strategy to improve outcomes in patients with myeloma bone disease.

Aberrant Transforming Growth Factor-β Activation Recruits Mesenchymal Stem Cells During Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is the overgrowth of prostate tissues with high prevalence in older men. BPH pathogenesis is not completely understood, but it is believed to be a result of de novo overgrowth of prostatic stroma. In this study, we show that aberrant activation of transforming growth factor‐β (TGF‐β) mobilizes mesenchymal/stromal stem cells (MSCs) in circulating blood, which are recruited for the prostatic stromal hyperplasia. Elevated levels of active TGF‐β were observed in both a phenylephrine‐induced prostatic hyperplasia mouse model and human BPH tissues. Nestin lineage tracing revealed that 39.6% ± 6.3% of fibroblasts and 73.3% ± 4.2% smooth muscle cells were derived from nestin⁺ cells in Nestin‐Cre, Rosa26‐YFP^flox/+mice. Nestin⁺ MSCs were increased in the prostatic hyperplasia mice. Our parabiosis experiment demonstrate that nestin⁺ MSCs were mobilized and recruited to the prostatic stroma of wild‐type mice and gave rise to the fibroblasts. Moreover, injection of a TGF‐β neutralizing antibody (1D11) inhibits mobilization of MSCs, their recruitment to the prostatic stroma and hyperplasia. Importantly, knockout of TβRII in nestin⁺ cell lineage ameliorated stromal hyperplasia. Thus, elevated levels of TGF‐β‐induced mobilization and recruitment of MSCs to the reactive stroma resulting in overgrowth of prostate tissues in BPH and, thus, inhibition of TGF‐β activity could be a potential therapy for BPH. Stem Cells Translational Medicine2017;6:394–404

TGF-β1 Is Present at High Levels in Wound Fluid from Breast Cancer Patients Immediately Post-Surgery, and Is Not Increased by Intraoperative Radiation Therapy (IORT)

In patients with low-risk breast cancer, intraoperative radiotherapy (IORT) during breast-conserving surgery is a novel and convenient treatment option for delivering a single high dose of irradiation directly to the tumour bed. However, edema and fibrosis can develop after surgery and radiotherapy, which can subsequently impair quality of life. TGF- β is a strong inducer of the extracellular matrix component hyaluronan (HA). TGF-β expression and HA metabolism can be modulated by irradiation experimentally, and are involved in edema and fibrosis. We therefore hypothesized that IORT may regulate these factors.Wound fluid (WF) draining from breast lumpectomy sites was collected and levels of TGF-β1 and HA were determined by ELISA. Proliferation and marker expression was analyzed in primary lymphatic endothelial cells (LECs) treated with recombinant TGF-β or WF. Our results show that IORT does not change TGF-β1 or HA levels in wound fluid draining from breast lumpectomy sites, and does not lead to accumulation of sHA oligosaccharides. Nevertheless, concentrations of TGF-β1 were high in WF from patients regardless of IORT, at concentrations well above those associated with fibrosis and the suppression of LEC identity. Consistently, we found that TGF-β in WF is active and inhibits LEC proliferation. Furthermore, all three TGF-β isoforms inhibited LEC proliferation and suppressed LEC marker expression at pathophysiologically relevant concentrations.

Given that TGF-β contributes to edema and plays a role in the regulation of LEC identity, we suggest that inhibition of TGF-β directly after surgery might prevent the development of side effects such as edema and fibrosis.

Inactivation of TGFβ receptors in stem cells drives cutaneous squamous cell carcinoma

Melanoma patients treated with oncogenic BRAF inhibitors can develop cutaneous squamous cell carcinoma (cSCC) within weeks of treatment, driven by paradoxical RAS/RAF/MAPK pathway activation. Here we identify frequent TGFBR1 and TGFBR2 mutations in human vemurafenib-induced skin lesions and in sporadic cSCC. Functional analysis reveals these mutations ablate canonical TGFβ Smad signalling, which is localized to bulge stem cells in both normal human and murine skin. MAPK pathway hyperactivation (through Braf(V600E) or Kras(G12D) knockin) and TGFβ signalling ablation (through Tgfbr1 deletion) in LGR5(+ve) stem cells enables rapid cSCC development in the mouse. Mutation of Tp53 (which is commonly mutated in sporadic cSCC) coupled with Tgfbr1 deletion in LGR5(+ve) cells also results in cSCC development. These findings indicate that LGR5(+ve) stem cells may act as cells of origin for cSCC, and that RAS/RAF/MAPK pathway hyperactivation or Tp53 mutation, coupled with loss of TGFβ signalling, are driving events of skin tumorigenesis.

Overview of Transforming Growth Factor β Superfamily Involvement in Glioblastoma Initiation and Progression

Glioblastoma, also known as glioblastoma multiforme (GBM), is the most aggressive of human brain tumors and has a stunning progression with a mean survival of one year from the date of diagnosis. High cell proliferation, angiogenesis and/or necrosis are histopathological features of this cancer, which has no efficient curative therapy. This aggressiveness is associated with particular heterogeneity of the tumor featuring multiple genetic and epigenetic alterations, but also with implications of aberrant signaling driven by growth factors. The transforming growth factor β (TGFβ) superfamily is a large group of structurally related proteins including TGFβ subfamily members Nodal, Activin, Lefty, bone morphogenetic proteins (BMPs) and growth and differentiation factor (GDF). It is involved in important biological functions including morphogenesis, embryonic development, adult stem cell differentiation, immune regulation, wound healing and inflammation. This superfamily is also considered to impact on cancer biology including that of GBM, with various effects depending on the member. The TGFβ subfamily, in particular, is overexpressed in some GBM types which exhibit aggressive phenotypes. This subfamily impairs anti-cancer immune responses in several ways, including immune cells inhibition and major histocompatibility (MHC) class I and II abolishment. It promotes GBM angiogenesis by inducing angiogenic factors such as vascular endothelial growth factor (VEGF), plasminogen activator inhibitor (PAI-I) and insulin- like growth factor-binding protein 7 (IGFBP7), contributes to GBM progression by inducing metalloproteinases (MMPs), "pro-neoplastic" integrins (αvβ3, α5β1) and GBM initiating cells (GICs) as well as inducing a GBM mesenchymal phenotype. Equally, Nodal promotes GICs, induces cancer metabolic switch and supports GBM cell proliferation, but is negatively regulated by Lefty. Activin promotes GBM cell proliferation while GDF yields immune-escape function. On the other hand, BMPs target GICS and induce differentiation and sensitivity to chemotherapy. This multifaceted involvement of this superfamily in GBM necessitates different strategies in anti-cancer therapy. While suppressing the TGFβ subfamily yields advantageous results, enhancing BMPs production is also beneficial.

The evolving role of monoclonal antibodies in the treatment of patients with advanced renal cell carcinoma: a systematic review

INTRODUCTION

While the majority of the vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) inhibitors currently used for the therapy of metastatic renal cell carcinoma (mRCC) are small molecule agents inhibiting multiple targets, monoclonal antibodies are inhibitors of specific targets, which may decrease off-target effects while preserving on-target activity. A few monoclonal antibodies have already been approved for mRCC (bevacizumab, nivolumab), while many others may play an important role in the therapeutic scenario of mRCC.

AREAS COVERED

This review describes emerging monoclonal antibodies for treating RCC. Currently, bevacizumab, a VEGF monoclonal antibody, is approved in combination with interferon for the therapy of metastatic RCC, while nivolumab, a Programmed Death (PD)-1 inhibitor, is approved following prior VEGF inhibitor treatment. Other PD-1 and PD-ligand (L)-1 inhibitors are undergoing clinical development.

EXPERT OPINION

Combinations of inhibitors of the PD1/PD-L1 axis with VEGF inhibitors or cytotoxic T-lymphocyte antigen (CTLA)-4 inhibitors have shown promising efficacy in mRCC. The development of biomarkers predictive for benefit and rational tolerable combinations are both important pillars of research to improve outcomes in RCC.

Trial Watch: Immunotherapy plus radiation therapy for oncological indications

Malignant cells succumbing to some forms of radiation therapy are particularly immunogenic and hence can initiate a therapeutically relevant adaptive immune response. This reflects the intrinsic antigenicity of malignant cells (which often synthesize a high number of potentially reactive neo-antigens) coupled with the ability of radiation therapy to boost the adjuvanticity of cell death as it stimulates the release of endogenous adjuvants from dying cells. Thus, radiation therapy has been intensively investigated for its capacity to improve the therapeutic profile of several anticancer immunotherapies, including (but not limited to) checkpoint blockers, anticancer vaccines, oncolytic viruses, Toll-like receptor (TLR) agonists, cytokines, and several small molecules with immunostimulatory effects. Here, we summarize recent preclinical and clinical advances in this field of investigation.