Identification of CSPG4 as a promising target for translational combinatorial approaches in osteosarcoma

Chimeric antigen receptor T cells in the treatment of osteosarcoma (Review)

Osteosarcoma (OS) is a frequently occurring primary bone tumor, mostly affecting children, adolescents and young adults. Before 1970, surgical resection was the main treatment method for OS, but the clinical results were not promising. Subsequently, the advent of chemotherapy has improved the prognosis of patients with OS. However, there is still a high incidence of metastasis or recurrence, and chemotherapy has several side effects, thus making the 5‑year survival rate markedly low. Recently, chimeric antigen receptor T (CAR‑T) cell therapy represents an alternative immunotherapy approach with significant potential for hematologic malignancies. Nevertheless, the application of CAR‑T cells in the treatment of OS faces numerous challenges. The present review focused on the advances in the development of CAR‑T cells to improve their clinical efficacy, and discussed ways to overcome the difficulties faced by CAR T‑cell therapy for OS.

Overall review of curative impact and barriers of CAR-T cells in osteosarcoma

Osteosarcoma (OS) is a rare form of cancer and primary bone malignancy in children and adolescents. Current therapies include surgery, chemotherapy, and amputation. Therefore, a new therapeutic strategy is needed to dramatically change cancer treatment. Recently, chimeric antigen receptor T cells (CAR-T cells) have been of considerable interest as it has provided auspicious results and patients suffering from low side effects after injection that resolve with current therapy. However, there are reports that cytokine release storm (CRS) can be observed in some patients. In addition, as researchers have faced problems that limit and suppress T cells, further studies are required to resolve these problems. In addition, to maximize the therapeutic benefit of CAR-T cell therapy, researchers have suggested that combination therapy could be better used to treat cancer by overcoming any problems and reducing side effects as much as possible. This review summarizes these problems, barriers, and the results of some studies on the evaluation of CAR-T cells in patients with osteosarcoma.

Current status and future challenges of CAR-T cell therapy for osteosarcoma

Osteosarcoma, the most common bone malignancy in children and adolescents, poses considerable challenges in terms of prognosis, especially for patients with metastatic or recurrent disease. While surgical intervention and adjuvant chemotherapy have improved survival rates, limitations such as impractical tumor removal or chemotherapy resistance hinder the treatment outcomes. Chimeric antigen receptor (CAR)-T cell therapy, an innovative immunotherapy approach that involves targeting tumor antigens and releasing immune factors, has shown significant advancements in the treatment of hematological malignancies. However, its application in solid tumors, including osteosarcoma, is constrained by factors such as low antigen specificity, limited persistence, and the complex tumor microenvironment. Research on osteosarcoma is ongoing, and some targets have shown promising results in pre-clinical studies. This review summarizes the current status of research on CAR-T cell therapy for osteosarcoma by compiling recent literature. It also proposes future research directions to enhance the treatment of osteosarcoma.

Screening tumor stage-specific candidate neoantigens in thyroid adenocarcinoma using integrated exome and transcriptome sequencing

Background

The incidence of thyroid carcinoma (THCA), the most common endocrine tumor, is continuously increasing worldwide. Although the overall prognosis of THCA is good, patients with distant metastases exhibit a mortality rate of 5-20%.

Methods

To improve the diagnosis and overall prognosis of patients with thyroid cancer, we screened specific candidate neoantigen genes in early- and late-stage THCA by analyzing the transcriptome and somatic cell mutations in this study.

Results

The top five early-stage neoantigen-related genes (NRGs) were G protein-coupled receptor 4 [GPR4], chondroitin sulfate proteoglycan 4 [CSPG4], teneurin transmembrane protein 1 [TENM1], protein S 1 [PROS1], and thymidine kinase 1 [TK1], whereas the top five late-stage NRGs were cadherin 6 [CDH6], semaphorin 6B [SEMA6B], dysferlin [DYSF], xenotropic and polytropic retrovirus receptor 1 [XPR1], and ABR activator of RhoGEF and GTPase [ABR]. Subsequently, we used machine learning models to verify their ability to screen NRGs and analyze the correlations among NRGs, immune cell types, and immune checkpoint regulators. The use of candidate antigen genes resulted in a better diagnostic model (the area under the curve [AUC] value of the early-stage group [0.979] was higher than that of the late-stage group [0.959]). Then, a prognostic model was constructed to predict NRG survival, and the 1-, 3- and 5-year AUC values were 0.83, 0.87, and 0.86, respectively, which were closely related to different immune cell types. Comparison of the expression trends and mutation frequencies of NRGs in multiple tumors revealed their potential for the development of broad spectrum therapeutic drugs.

Conclusion

In conclusion, the candidate NRGs identified in this study could potentially be used as therapeutic targets and diagnostic biomarkers for the development of novel broad spectrum therapeutic agents.

Immunohistochemical detection of the chondroitin sulfate proteoglycan 4 protein in primary and metastatic melanoma

Treatment of malignant melanoma, the most aggressive form of skin cancer, continues to be a major challenge for clinicians. New targeted therapies with kinase inhibitors or drugs which modify the immune response are often accompanied by the development of resistance or severe side effects. In this context, chondroitin sulfate proteoglycan 4 (CSPG4), a highly immunogenic melanoma tumor antigen, could be a potential target for alternative therapeutic approaches. The aim of the present study was to identify differences in the levels of CSPG4 protein expression in primary and metastatic melanomas as well as to analyze correlations between CSPG4 expression and histopathological data and patient characteristics. A total of 189 melanoma tissue samples from Lower Austria, including primary melanomas and melanoma metastases, were immunohistochemically stained for the expression of CSPG4 and statistical analyses were performed. A total of 65.6% of melanoma tissue samples stained positive for the expression of CSPG4. Primary nodular and primary superficial spreading melanomas demonstrated a significantly higher number of positively stained tissue samples for CSPG4 compared with primary lentigo maligna melanomas. No significant differences in the expression of CSPG4 were demonstrated between primary melanomas and melanoma metastases. The present study supports the advancement of the understanding of CSPG4 tissue expression patterns in melanoma patients and provides additional information for further investigation of CSPG4 as a potential therapeutic target.

A chimeric human/dog-DNA vaccine against CSPG4 induces immunity with therapeutic potential in comparative preclinical models of osteosarcoma

The high mortality rate of osteosarcoma (OSA) patients highlights the requirement of alternative strategies. The young age of patients, as well as the rarity and aggressiveness of the disease, limits opportunities for the robust testing of novel therapies, suggesting the need for valuable preclinical systems. Having previously shown the overexpression of the chondroitin sulfate proteoglycan (CSPG)4 in OSA, herein the functional consequences of its downmodulation in human OSA cells were evaluated in vitro, with a significant impairment of cell proliferation, migration, and osteosphere generation. The potential of a chimeric human/dog (HuDo)-CSPG4 DNA vaccine was explored in translational comparative OSA models, including human xenograft mouse models and canine patients affected by spontaneous OSA. The adoptive transfer of HuDo-CSPG4 vaccine-induced CD8+ T cells and sera in immunodeficient human OSA-bearing mice delayed tumor growth and metastasis development. HuDo-CSPG4 vaccination resulted safe and effective in inducing anti-CSPG4 immunity in OSA-affected dogs, which displayed prolonged survival as compared to controls. Finally, HuDo-CSPG4 was also able to induce a cytotoxic response in a human surrogate setting in vitro. On the basis of these results and the high predictive value of spontaneous OSA in dogs, this study paves the way for a possible translation of this approach to humans.

Improving Osteosarcoma Treatment: Comparative Oncology in Action

Osteosarcoma (OSA) is the most common pediatric malignant bone tumor. Although surgery together with neoadjuvant/adjuvant chemotherapy has improved survival for localized OSA, most patients develop recurrent/metastatic disease with a dismally poor outcome. Therapeutic options have not improved for these OSA patients in recent decades. As OSA is a rare and "orphan" tumor, with no distinct targetable driver antigens, the development of new efficient therapies is still an unmet and challenging clinical need. Appropriate animal models are therefore critical for advancement in the field. Despite the undoubted relevance of pre-clinical mouse models in cancer research, they present some intrinsic limitations that may be responsible for the low translational success of novel therapies from the pre-clinical setting to the clinic. From this context emerges the concept of comparative oncology, which has spurred the study of pet dogs as a uniquely valuable model of spontaneous OSA that develops in an immune-competent system with high biological and clinical similarities to corresponding human tumors, including in its metastatic behavior and resistance to conventional therapies. For these reasons, the translational power of studies conducted on OSA-bearing dogs has seen increasing recognition. The most recent and relevant veterinary investigations of novel combinatorial approaches, with a focus on immune-based strategies, that can most likely benefit both canine and human OSA patients have been summarized in this commentary.

Chondroitin Sulfate Proteoglycan 4 as a Marker for Aggressive Squamous Cell Carcinoma

Chondroitin sulfate (CS) proteoglycan 4 (CSPG4) is a cell surface proteoglycan that is currently under investigation as a marker of cancer malignancy, and as a potential target of anticancer drug treatment. CSPG4 acts as a driver of tumourigenesis by regulating turnover of the extracellular matrix (ECM) to promote tumour cell invasion, migration as well as inflammation and angiogenesis. While CSPG4 has been widely studied in certain malignancies, such as melanoma, evidence is emerging from global gene expression studies, which suggests a role for CSPG4 in squamous cell carcinoma (SCC). While relatively treatable, lack of widely agreed upon diagnostic markers for SCCs is problematic, especially for clinicians managing certain patients, including those who are aged or infirm, as well as those with underlying conditions such as epidermolysis bullosa (EB), for which a delayed diagnosis is likely lethal. In this review, we have discussed the structure of CSPG4, and quantitatively analysed CSPG4 expression in the tissues and pathologies where it has been identified to determine the usefulness of CSPG4 expression as a diagnostic marker and therapeutic target in management of malignant SCC.

CSPG4 expression in soft tissue sarcomas is associated with poor prognosis and low cytotoxic immune response

Background

Soft tissue sarcomas (STS) are heterogeneous and pro-metastatic tumors. Identification of accurate prognostic factors and novel therapeutic targets are crucial. CSPG4 is a cell surface proteoglycan with oncogenic functions. It recently emerged as a potential target for immunotherapy, including cell therapy based on CSPG4-specific chimeric antigen receptor (CAR)-redirected cytokine-induced killer lymphocytes (CSPG4-CAR.CIKs) in STS. However, expression of CSPG4 is poorly known in STS so far.

Methods

We analyzed CSPG4 gene expression in 1378 localized STS clinical samples, and searched for correlations with clinicopathological data, including disease-free survival (DFS), and with tumor immune features.

Results

CSPG4 expression was heterogeneous across samples. High expression was associated with younger patients’ age, more frequent undifferentiated pleomorphic sarcoma and myxofibrosarcoma pathological subtypes, more frequent internal trunk tumor site, and more CINSARC high-risk samples. No correlation existed with pathological tumor size and grade, and tumor depth. Patients with high CSPG4 expression displayed 49% (95% CI 42–57) 5-year DFS versus 61% (95% CI 56–68) in patients with low expression (p = 3.17E−03), representing a 49% increased risk of event in the “CSPG4-high” group (HR = 1.49, 95% CI 1.14–1.94). This unfavorable prognostic value persisted in multivariate analysis, independently from other variables. There were significant differences in immune variables between “CSPG4-high” and “CSPG4-low” tumors. The "CSPG4-low" tumors displayed profiles suggesting higher anti-tumor cytotoxic immune response and higher potential vulnerability to immune checkpoint inhibitors (ICI). By contrast, the "CSPG4-high" tumors displayed profiles implying an immune-excluded tumor microenvironment, potentially induced by hypoxia, resulting from an immature chaotic microvasculature, and/or the presence of contractile myofibroblasts.

Conclusions

Patients with “CSPG4-high” STS, theoretically candidate for CAR.CIKs, display shorter DFS and an immune environment unfavorable to vulnerability to CAR.CIKs, which could be improved by combining anti-angiogenic drugs able to normalize the tumor vasculature. By contrast, “CSPG4-low” STS are better candidates for immune therapy involving ICI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03679-y.

Chondroitin sulfate proteoglycan 4 expression in chondrosarcoma: A potential target for antibody-based immunotherapy

Chondrosarcoma is a common primary bone malignancy whose phenotype increases with its histologic grade. They are relatively resistant to chemotherapy and radiation therapy limiting curative options for disseminated disease. Chondroitin sulfate proteoglycan 4 (CSPG4) is a cell surface proteoglycan that is highly expressed across various human cancers, including chondrosarcoma, and has restricted distribution in healthy tissues, making it an attractive target for the antibody-based therapy. CSPG4 specific chimeric antigen receptor (CAR) T cell therapies have been shown to be effective in treating other cancers such as melanoma and triple negative breast cancer. The goal of this study was to assess the prevalence of CSPG4 in human chondrosarcoma and to assess the efficacy of CSPG4 specific CAR T cells in lysing chondrosarcoma cells in vitro. Using immunohistochemistry (IHC), we stained a tissue microarray containing primary conventional and dedifferentiated chondrosarcoma from 76 patients with CSPG4 specific monoclonal antibodies (mAbs). In addition, we incubated 2 chondrosarcoma cell lines with CSPG4-targeting CAR T cells and subsequently evaluated cell survival. Our results showed medium to high expression of CSPG4 in 29 of 41 (71%) conventional chondrosarcoma tumors and in 3 of 20 (15%) dedifferentiated chondrosarcoma tumors. CSPG4 expression showed a positive association with time to metastasis and survival in both subtypes. CSPG4 CAR T treated cell lines showed a lysis of respectively >80% and 70% demonstrating CSPG4-targeted CAR T cells effective in killing CSPG4-positive chondrosarcoma tumors.

Canine Melanoma Immunology and Immunotherapy: Relevance of Translational Research

In veterinary oncology, canine melanoma is still a fatal disease for which innovative and long-lasting curative treatments are urgently required. Considering the similarities between canine and human melanoma and the clinical revolution that immunotherapy has instigated in the treatment of human melanoma patients, special attention must be paid to advancements in tumor immunology research in the veterinary field. Herein, we aim to discuss the most relevant knowledge on the immune landscape of canine melanoma and the most promising immunotherapeutic approaches under investigation. Particular attention will be dedicated to anti-cancer vaccination, and, especially, to the encouraging clinical results that we have obtained with DNA vaccines directed against chondroitin sulfate proteoglycan 4 (CSPG4), which is an appealing tumor-associated antigen with a key oncogenic role in both canine and human melanoma. In parallel with advances in therapeutic options, progress in the identification of easily accessible biomarkers to improve the diagnosis and the prognosis of melanoma should be sought, with circulating small extracellular vesicles emerging as strategically relevant players. Translational advances in melanoma management, whether achieved in the human or veterinary fields, may drive improvements with mutual clinical benefits for both human and canine patients; this is where the strength of comparative oncology lies.

Chimeric Antigen Receptor T-Cell Therapy: The Light of Day for Osteosarcoma

Simple Summary

As a novel immunotherapy, chimeric antigen receptor (CAR) T-cell therapy has achieved encouraging results in leukemia and lymphoma. Furthermore, CAR-T cells have been explored in the treatment of osteosarcoma (OS). However, there is no strong comprehensive evidence to support their efficacy. Therefore, we reviewed the current evidence on CAR-T cells for OS to demonstrate their feasibility and provide new options for the treatment of OS.

Abstract

Osteosarcoma (OS) is the most common malignant bone tumor, arising mainly in children and adolescents. With the introduction of multiagent chemotherapy, the treatments of OS have remarkably improved, but the prognosis for patients with metastases is still poor, with a five-year survival rate of 20%. In addition, adverse effects brought by traditional treatments, including radical surgery and systemic chemotherapy, may seriously affect the survival quality of patients. Therefore, new treatments for OS await exploitation. As a novel immunotherapy, chimeric antigen receptor (CAR) T-cell therapy has achieved encouraging results in treating cancer in recent years, especially in leukemia and lymphoma. Furthermore, researchers have recently focused on CAR-T therapy in solid tumors, including OS. In this review, we summarize the safety, specificity, and clinical transformation of the targets in treating OS and point out the direction for further research.

Carbohydrate sulfotransferase 3 (CHST3) overexpression promotes cartilage endplate-derived stem cells (CESCs) to regulate molecular mechanisms related to repair of intervertebral disc degeneration by rat nucleus pulposus

To investigate the regulatory effect of carbohydrate sulfotransferase 3 (CHST3) in cartilage endplate-derived stem cells (CESCs) on the molecular mechanism of intervertebral disc degeneration after nucleus pulposus repair in rats. We performed GO and KEGG analysis of GSE15227 database to select the differential genes CHST3 and CSPG4 in grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration, IHC and WB to detect the protein profile of CHST3 and CSPG4, Co-IP for the interaction between CHST3 and CSPG4. Then, immunofluorescence was applied to measure the level of CD90 and CD105, and flow cytometry indicated the level of CD73, CD90 and CD105 in CESCs. Next, Alizarin red staining, Alcian blue staining and TEM were performed to evaluate the effects of CESCs into osteoblasts and chondroblasts, respectively, CCK8 for the cell proliferation of osteoblasts and chondroblasts after induction for different times; cell cycle of osteoblasts or chondroblasts was measured by flow cytometry after induction, and WB for the measurement of specific biomarkers of OC and RUNX in osteoblasts and aggrecan, collagen II in chondroblasts. Finally, colony formation was applied to measure the cell proliferation of CESCs transfected with ov-CHST3 or sh-CHST3 when cocultured with bone marrow cells, WB for the protein expression of CHST3, CSPG4 and ELAVL1 in CSECs, transwell assay for the migration of CESCs to bone marrow cells, TEM image for the cellular characteristics of bone marrow cells, and WB for the protein profile of VCAN, VASP, NCAN and OFD1 in bone marrow cells. CHST3 and CSPG4 were differentially expressed and interacted in grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration; CD73, CD90 and CD105 were lowly expressed in CESCs, osteogenic or chondroblastic induction changed the characteristics, proliferation, cell cycle and specific biomarkers of osteoblasts and chondroblasts after 14 or 21 days,; CHST3 affected the cell proliferation, protein profile, migration and cellular features of cocultured CESCs or bone marrow cells. CHST3 overexpression promoted CESCs to regulate bone marrow cells through interaction with CSPG4 to repair the grade Ⅱ, Ⅲ and Ⅳ intervertebral disc degeneration.

In vivo safety profile of a CSPG4-directed IgE antibody in an immunocompetent rat model

IgE monoclonal antibodies hold great potential for cancer therapy. Preclinical in vivo systems, particularly those in which the antibody recognizes the host species target antigen and binds to cognate Fc receptors, are often the closest approximation to human exposure and represent a key challenge for evaluating the safety of antibody-based therapies. We sought to develop an immunocompetent rat system to assess the safety of a rodent anti-tumor IgE, as a surrogate for the human therapeutic candidate. We generated a rat IgE against the human tumor-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4) and cross-reactive for the rat antigen. We analyzed CSPG4 distribution in normal rat and human tissues and investigated the in vivo safety of the antibody by monitoring clinical signs and molecular biomarkers after systemic administration to immunocompetent rats. Human and rat CSPG4 expression in normal tissues were comparable. Animals receiving antibody exhibited transient mild to moderate adverse events accompanied by mild elevation of serum tryptase, but not of angiotensin II or cytokines implicated in allergic reactions or cytokine storm. In the long term, repeated antibody administration was well tolerated, with no changes in animal body weight, liver and kidney functions or blood cell counts. This model provides preclinical support for the safety profiling of IgE therapeutic antibodies. Due to the comparable antigen tissue distribution in human and rat, this model may also comprise an appropriate tool for proof-of-concept safety evaluations of different treatment approaches targeting CSPG4.

Electroporation-Based Treatments in Small Animal Veterinary Oral and Maxillofacial Oncology

Electroporation is a method of inducing an increase in permeability of the cell membrane through the application of an electric field and can be used as a delivery method for introducing molecules of interest (e.g., chemotherapeutics or plasmid DNA) into cells. Electroporation-based treatments (i.e., electrochemotherapy, gene electrotransfer, and their combinations) have been shown to be safe and effective in veterinary oncology, but they are currently mostly recommended for the treatment of those solid tumors for which clients have declined surgery and/or radiotherapy. Published data show that electroporation-based treatments are also safe, simple, fast and cost-effective treatment alternatives for selected oral and maxillofacial tumors, especially small squamous cell carcinoma and malignant melanoma tumors not involving the bone in dogs. In these patients, a good local response to treatment is expected to result in increased survival time with good quality of life. Despite emerging evidence of the clinical efficacy of electroporation-based treatments for oral and maxillofacial tumors, further investigation is needed to optimize treatment protocols, improve clinical data reporting and better understand the mechanisms of patients' response to the treatment.

Development of a VLP-Based Vaccine Displaying an xCT Extracellular Domain for the Treatment of Metastatic Breast Cancer

Metastatic breast cancer (MBC) is the leading cause of cancer death in women due to recurrence and resistance to conventional therapies. Thus, MBC represents an important unmet clinical need for new treatments. In this paper we generated a virus-like particle (VLP)-based vaccine (AX09) to inhibit de novo metastasis formation and ultimately prolong the survival of patients with MBC. To this aim, we engineered the bacteriophage MS2 VLP to display an extracellular loop of xCT, a promising therapeutic target involved in tumor progression and metastasis formation. Elevated levels of this protein are observed in a high percentage of invasive mammary ductal tumors including triple negative breast cancer (TNBC) and correlate with poor overall survival. Moreover, xCT expression is restricted to only a few normal cell types. Here, we tested AX09 in several MBC mouse models and showed that it was well-tolerated and elicited a strong antibody response against xCT. This antibody-based response resulted in the inhibition of xCT's function in vitro and reduced metastasis formation in vivo. Thus, AX09 represents a promising novel approach for MBC, and it is currently advancing to clinical development.

Oncofetal Chondroitin Sulfate: A Putative Therapeutic Target in Adult and Pediatric Solid Tumors

Solid tumors remain a major challenge for targeted therapeutic intervention strategies such as antibody-drug conjugates and immunotherapy. At a minimum, clear and actionable solid tumor targets have to comply with the key biological requirement of being differentially over-expressed in solid tumors and metastasis, in contrast to healthy organs. Oncofetal chondroitin sulfate is a cancer-specific secondary glycosaminoglycan modification to proteoglycans expressed in a variety of solid tumors and metastasis. Normally, this modification is found to be exclusively expressed in the placenta, where it is thought to facilitate normal placental implantation during pregnancy. Informed by this biology, oncofetal chondroitin sulfate is currently under investigation as a broad and specific target in solid tumors. Here, we discuss oncofetal chondroitin sulfate as a potential therapeutic target in childhood solid tumors in the context of current knowhow obtained over the past five years in adult cancers.

Chondroitin sulfate derived theranostic and therapeutic nanocarriers for tumor-targeted drug delivery

The standard chemotherapy is facing the challenges of lack of cancer selectivity and development of drug resistance. Currently, with the application of nanotechnology, the rationally designed nanocarriers of chondroitin sulfate (CS) have been fabricated and their unique features of low toxicity, biocompatibility, and active and passive targeting made them drug delivery vehicles of the choice for cancer therapy. The hydrophilic and anionic CS could be incorporated as a building block into- or decorated on the surface of nanoformulations. Micellar nanoparticles (NPs) self-assembled from amphiphilic CS-drug conjugates and CS-polymer conjugates, polyelectrolyte complexes (PECs) and nanogels of CS have been widely implicated in cancer directed therapy. The surface modulation of organic, inorganic, lipid and metallic NPs with CS promotes the receptor-mediated internalization of NPs to the tumor cells. The potential contribution of CS and CS-proteoglycans (CSPGs) in the pathogenesis of various cancer types, and CS nanocarriers in immunotherapy, radiotherapy, sonodynamic therapy (SDT) and photodynamic therapy (PDT) of cancer are summarized in this review paper.

Chondroitin Sulphate Proteoglycans in the Tumour Microenvironment

Proteoglycans are macromolecules that are essential for the development of cells, human diseases and malignancies. In particular, chondroitin sulphate proteoglycans (CSPGs) accumulate in tumour stroma and play a key role in tumour growth and invasion by driving multiple oncogenic pathways in tumour cells and promoting crucial interactions in the tumour microenvironment (TME). These pathways involve receptor tyrosine kinase (RTK) signalling via the mitogen-activated protein kinase (MAPK) cascade and integrin signalling via the activation of focal adhesion kinase (FAK), which sustains the activation of extracellular signal-regulated kinases 1/2 (ERK1/2).Human CSPG4 is a type I transmembrane protein that is associated with the growth and progression of human brain tumours. It regulates cell signalling and migration by interacting with components of the extracellular matrix, extracellular ligands, growth factor receptors, intracellular enzymes and structural proteins. Its overexpression by tumour cells, perivascular cells and precursor/progenitor cells in gliomas suggests that it plays a role in their origin, progression and neo-angiogenesis and its aberrant expression in tumour cells may be a promising biomarker to monitor malignant progression and patient survival.The aim of this chapter is to review and discuss the role of CSPG4 in the TME of human gliomas, including its potential as a druggable therapeutic target.

Naturally occurring cancers in pet dogs as pre-clinical models for cancer immunotherapy

Despite the significant progress in tumor prevention, early detection, diagnosis and treatment made over recent decades, cancer is still an enormous public health challenge all around the world, with the number of people affected increasing every year. A great deal of effort is therefore being devoted to the search for novel safe, effective and economically sustainable treatments for the growing population of neoplastic patients. One main obstacle to this process is the extremely low percentage of therapeutic approaches that, after successfully passing pre-clinical testing, actually demonstrate activity when finally tested in humans. This disappointing and expensive failure rate is partly due to the pre-clinical murine models used for in vivo testing, which cannot faithfully recapitulate the multifaceted nature and evolution of human malignancies. These features are better mirrored in natural disease models, i.e., companion animals affected by cancers. Herein, we discuss the relevance of spontaneous canine tumors for the evaluation of the safety and anti-tumor activity of novel therapeutic strategies before in-human trials, and present our experience in the development of a vaccine that targets chondroitin sulphate proteoglycan (CSPG)4 as an example of these comparative oncology studies.