Glioblastoma exosomes and IGF-1R/AS-ODN are immunogenic stimuli in a translational research immunotherapy paradigm

Autologous cell immunotherapy (IGV-001) with IGF-1R antisense oligonucleotide in newly diagnosed glioblastoma patients

Standard-of-care first-line therapy for patients with newly diagnosed glioblastoma (ndGBM) is maximal safe surgical resection, then concurrent radiotherapy and temozolomide, followed by maintenance temozolomide. IGV-001, the first product of the Goldspire™ platform, is a first-in-class autologous immunotherapeutic product that combines personalized whole tumor-derived cells with an antisense oligonucleotide (IMV-001) in implantable biodiffusion chambers, with the intent to induce a tumor-specific immune response in patients with ndGBM. Here, we describe the design and rationale of a randomized, double-blind, phase IIb trial evaluating IGV-001 compared with placebo, both followed by standard-of-care treatment in patients with ndGBM. The primary end point is progression-free survival, and key secondary end points include overall survival and safety.

Manipulating the tumor immune microenvironment to improve cancer immunotherapy: IGF1R, a promising target

Cancer immunotherapy has made impressive advances in improving the outcome of patients affected by malignant diseases. Nonetheless, some limitations still need to be tackled to more efficiently and safely treat patients, in particular for those affected by solid tumors. One of the limitations is related to the immunosuppressive tumor microenvironment (TME), which impairs anti-tumor immunity. Efforts to identify targets able to turn the TME into a milieu more auspicious to current immuno-oncotherapy is a real challenge due to the high redundancy of the mechanisms involved. However, the insulin-like growth factor 1 receptor (IGF1R), an attractive drug target for cancer therapy, is emerging as an important immunomodulator and regulator of key immune cell functions. Here, after briefly summarizing the IGF1R signaling pathway in cancer, we review its role in regulating immune cells function and activity, and discuss IGF1R as a promising target to improve anti-cancer immunotherapy.

Effects of glioblastoma-derived extracellular vesicles on the functions of immune cells

Glioblastoma is the most aggressive variant of glioma, the tumor of glial origin which accounts for 80% of brain tumors. Glioblastoma is characterized by astoundingly poor prognosis for patients; a combination of surgery, chemo- and radiotherapy used for clinical treatment of glioblastoma almost inevitably results in rapid relapse and development of more aggressive and therapy resistant tumor. Recently, it was demonstrated that extracellular vesicles produced by glioblastoma (GBM-EVs) during apoptotic cell death can bind to surrounding cells and change their phenotype to more aggressive. GBM-EVs participate also in establishment of immune suppressive microenvironment that protects glioblastoma from antigen-specific recognition and killing by T cells. In this review, we collected present data concerning characterization of GBM-EVs and study of their effects on different populations of the immune cells (T cells, macrophages, dendritic cells, myeloid-derived suppressor cells). We aimed at critical analysis of experimental evidence in order to conclude whether glioblastoma-derived extracellular vesicles are a major factor in immune evasion of this deadly tumor. We summarized data concerning potential use of GBM-EVs for non-invasive diagnostics of glioblastoma. Finally, the applicability of approaches aimed at blocking of GBM-EVs production or their fusion with target cells for treatment of glioblastoma was analyzed.

Drugging IGF-1R in cancer: New insights and emerging opportunities

The insulin-like growth factor (IGF) axis plays important roles in cancer development and metastasis. The type 1 IGF receptor (IGF-1R) is a key member in the IGF axis and has long been recognized for its oncogenic role in multiple cancer lineages. Here we review the occurrence of IGF-1R aberrations and activation mechanisms in cancers, which justify the development of anti-IGF-1R therapies. We describe the therapeutic agents available for IGF-1R inhibition, with focuses on the recent or ongoing pre-clinical and clinical studies. These include antisense oligonucleotide, tyrosine kinase inhibitors and monoclonal antibodies which may be conjugated with cytotoxic drug. Remarkably, simultaneous targeting of IGF-1R and several other oncogenic vulnerabilities has shown early promise, highlighting the potential benefits of combination therapy. Further, we discuss the challenges in targeting IGF-1R so far and new concepts to improve therapeutic efficacy such as blockage of the nuclear translocation of IGF-1R.

Challenges and Opportunities for Immunotherapeutic Intervention against Myeloid Immunosuppression in Glioblastoma

Glioblastoma multiforme (GBM), the most common and deadly brain cancer, exemplifies the paradigm that cancers grow with help from an immunosuppressive tumor microenvironment (TME). In general, TME includes a large contribution from various myeloid lineage-derived cell types, including (in the brain) altered pathogenic microglia as well as monocyte-macrophages (Macs), myeloid-derived suppressor cells (MDSC) and dendritic cell (DC) populations. Each can have protective roles, but has, by definition, been coopted by the tumor in patients with progressive disease. However, evidence demonstrates that myeloid immunosuppressive activities can be reversed in different ways, leading to enthusiasm for this therapeutic approach, both alone and in combination with potentially synergistic immunotherapeutic and other strategies. Here, we review the current understanding of myeloid cell immunosuppression of anti-tumor responses as well as potential targets, challenges, and developing means to reverse immunosuppression with various therapeutics and their status. Targets include myeloid cell colony stimulating factors (CSFs), insulin-like growth factor 1 (IGF1), several cytokines and chemokines, as well as CD40 activation and COX2 inhibition. Approaches in clinical development include antibodies, antisense RNA-based drugs, cell-based combinations, polarizing cytokines, and utilizing Macs as a platform for Chimeric Antigen Receptors (CAR)-based tumor targeting, like with CAR-T cells. To date, promising clinical results have been reported with several of these approaches.

Brain Cancer Drug Discovery: Clinical Trials, Drug Classes, Targets, and Combinatorial Therapies

Brain cancer is a formidable challenge for drug development, and drugs derived from many cutting-edge technologies are being tested in clinical trials. We manually characterized 981 clinical trials on brain tumors that were registered in ClinicalTrials.gov from 2010 to 2020. We identified 582 unique therapeutic entities targeting 581 unique drug targets and 557 unique treatment combinations involving drugs. We performed the classification of both the drugs and drug targets based on pharmacological and structural classifications. Our analysis demonstrates a large diversity of agents and targets. Currently, we identified 32 different pharmacological directions for therapies that are based on 42 structural classes of agents. Our analysis shows that kinase inhibitors, chemotherapeutic agents, and cancer vaccines are the three most common classes of agents identified in trials. Agents in clinical trials demonstrated uneven distribution in combination approaches; chemotherapy agents, proteasome inhibitors, and immune modulators frequently appeared in combinations, whereas kinase inhibitors, modified immune effector cells did not as was shown by combination networks and descriptive statistics. This analysis provides an extensive overview of the drug discovery field in brain cancer, shifts that have been happening in recent years, and challenges that are likely to come. SIGNIFICANCE STATEMENT: This review provides comprehensive quantitative analysis and discussion of the brain cancer drug discovery field, including classification of drug, targets, and therapies.

Glioblastoma Contains Topologically Distinct Proliferative and Metabolically Defined Subpopulations of Nestin- and Glut1-Expressing Cells

The difficulty in treatment of glioblastoma is a consequence of its natural infiltrative growth and the existence of a population of therapy-resistant glioma cells that contribute to growth and recurrence. To identify cells more likely to have these properties, we examined the expression in tumor specimens of several protein markers important for glioma progression including the intermediate filament protein, Nestin (NES), a glucose transporter (Glut1/SLC2A1), the glial lineage marker, glial fibrillary acidic protein, and the proliferative indicator, Ki-67. We also examined the expression of von Willebrand factor, a marker for endothelial cells as well as the macrophage/myeloid markers CD163 and CD15. Using a multicolor immunofluorescence and hematoxylin and eosin staining approach with archival formalin-fixed, paraffin embedded tissue from primary, recurrent, and autopsy IDH1 wildtype specimens combined with high-resolution tissue image analysis, we have identified highly proliferative NES(+)/Glut1(-) cells that are preferentially perivascular. In contrast, Glut1(+)/NES(-) cells are distant from blood vessels, show low proliferation, and are preferentially located at the borders of pseudopalisading necrosis. We hypothesize that Glut1(+)/NES(-) cells would be naturally resistant to conventional chemotherapy and radiation due to their low proliferative capacity and may act as a reservoir for tumor recurrence.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

Current Development of Glioblastoma Therapeutic Agents

Glioblastoma multiforme (GBM) is the most common and aggressive malignant primary brain tumor in humans. Over the past several decades, despite improvements in neurosurgical techniques, development of powerful chemotherapeutic agents, advances in radiotherapy, and comprehensive genomic profiling and molecular characterization, treatment of GBM has achieved very limited success in increasing overall survival. Thus, identifying and understanding the key molecules and barriers responsible for the malignant phenotypes and treatment resistance of GBM will yield new potential therapeutic targets. We review the most recent development of receptor tyrosine kinase targeted therapy for GBM and discuss the current status of several novel strategies with the emphasis on blood-brain barrier penetration as a major obstacle for small-molecule drugs to achieve their therapeutic goals. Likewise, a major opportunity for the treatment of GBM lies in the use of biomarkers for the discovery and development of new receptor tyrosine kinase targeted therapy.

Systemic Immune Bias Delineates Malignant Astrocytoma Survival Cohorts

Patients with grade III anaplastic astrocytomas (AA) separate into survival cohorts based on the presence or absence of mutations in isocitrate dehydrogenase (IDH). Progression to glioblastoma (GBM), morphologically distinguishable by elevated microvascular proliferation, necrosis, and cell division in tumor tissues, is considerably more rapid in IDH wild-type tumors such that their diagnosis as AA is relatively rare. More often initially presenting as GBM, these contain higher numbers of tumor-associated macrophages (TAMs) than most AA, and GBM patients also have higher levels of circulating M2 monocytes. TAM and M2 monocytes share functional properties inhibitory for antitumor immunity. Yet, although there is a wealth of data implicating TAM in tumor-immune evasion, there has been limited analysis of the impact of the circulating M2 monocytes. In the current study, immune parameters in sera, circulating cells, and tumor tissues from patients with primary gliomas morphologically diagnosed as AA were assessed. Profound differences in serum cytokines, glioma extracellular vesicle cross-reactive Abs, and gene expression by circulating cells identified two distinct patient cohorts. Evidence of type 2-immune bias was most often seen in patients with IDH wild-type AA, whereas a type 1 bias was common in patients with tumors expressing the IDH1R132H mutation. Nevertheless, a patient's immune profile was better correlated with the extent of tumor vascular enhancement on magnetic resonance imaging than IDH mutational status. Regardless of IDH genotype, AA progression appears to be associated with a switch in systemic immune bias from type 1 to type 2 and the loss of tumor vasculature integrity.

Extracellular vesicles in cancer nanomedicine

To date, a lot of nanotechnological optitions are available for targeted drug delivery. Extracellular vesicles (EVs) are membrane structures that cells use for storage, transport, communication, and signaling. Recent research has focused on EVs as natural nanoparticles for drug delivery. This review sheds light on the application of EVs in cancer therapy, such as targeted chemotherapy, gene therapy, and vaccine development. Aspects of biogenesis, isolation, targeting, and loading of EVs are discussed in detail.

Brain-Derived Extracellular Vesicles in Health and Disease: A Methodological Perspective

Extracellular vesicles (EVs) are double membrane structures released by presumably all cell types that transport and deliver lipids, proteins, and genetic material to near or distant recipient cells, thereby affecting their phenotype. The basic knowledge of their functions in healthy and diseased brain is still murky and many questions about their biology are unsolved. In neurological diseases, EVs are regarded as attractive biomarkers and as therapeutic tools due to their ability to cross the blood–brain barrier (BBB). EVs have been successfully isolated from conditioned media of primary brain cells and cerebrospinal fluid (CSF), but protocols allowing for the direct study of pathophysiological events mediated or influenced by EVs isolated from brain have only recently been published. This review aims to give a brief overview of the current knowledge of EVs’ functions in the central nervous system (CNS) and the current protocols to isolate brain-derived EVs (BDEVs) used in different publications. By comparing the proteomic analysis of some of these publications, we also assess the influence of the isolation method on the protein content of BDEVs.

Phase Ib Clinical Trial of IGV-001 for Patients with Newly Diagnosed Glioblastoma

PURPOSE

Despite standard of care (SOC) established by Stupp, glioblastoma remains a uniformly poor prognosis. We evaluated IGV-001, which combines autologous glioblastoma tumor cells and an antisense oligonucleotide against IGF type 1 receptor (IMV-001), in newly diagnosed glioblastoma.

PATIENTS AND METHODS

This open-label protocol was approved by the Institutional Review Board at Thomas Jefferson University. Tumor cells collected during resection were treated ex vivo with IMV-001, encapsulated in biodiffusion chambers with additional IMV-001, irradiated, then implanted in abdominal acceptor sites. Patients were randomized to four exposure levels, and SOC was initiated 4-6 weeks later. On the basis of clinical improvements, randomization was halted after patient 23, and subsequent patients received only the highest exposure. Safety and tumor progression were primary and secondary objectives, respectively. Time-to-event outcomes were compared with the SOC arms of published studies.

RESULTS

Thirty-three patients were enrolled, and median follow-up was 3.1 years. Six patients had adverse events (grade ≤3) possibly related to IGV-001. Median progression-free survival (PFS) was 9.8 months in the intent-to-treat population (vs. SOC, 6.5 months; P = 0.0003). In IGV-001-treated patients who met Stupp-eligible criteria, PFS was 11.6 months overall (n = 22; P = 0.001) and 17.1 months at the highest exposure (n = 10; P = 0.0025). The greatest overall survival was observed in Stupp-eligible patients receiving the highest exposure (median, 38.2 months; P = 0.044). Stupp-eligible patients with methylated O⁶-methylguanine-DNA methyltransferase promoter (n = 10) demonstrated median PFS of 38.4 months (P = 0.0008). Evidence of immune activation was noted.

CONCLUSIONS

IGV-001 was well tolerated, PFS compared favorably with SOC, and evidence suggested an immune-mediated mechanism (ClinicalTrials.gov: NCT02507583).

Extracellular vesicles in cancer progression: are they part of the problem or part of the solution?

Extracellular vesicles (EVs) are released especially by cancer cells. They modulate the tumor microenvironment by interacting with immune cells while carrying immunosuppressive or immunostimulatory molecules. In this review, we will explore some conflicting reports regarding the immunological outcomes of EVs in cancer progression, in which they might initiate an antitumor immune response or an immunosuppressive response. Concerning immunosuppression, the role of tumor-derived EVs' in the adenosinergic system is underexplored. The enhancement of adenosine (ADO) levels in the tumor microenvironment impairs T-cell function and cytokine release. However, some tumor-derived EVs may deliver immunostimulatory factors, promoting immunogenic activity, even with ADO production. The modulatory role of ADO over the tumor progression represents a piece in an intricate microenvironment with anti and pro tumoral seesaw-like mechanisms.

Immunotherapy for gliomas: shedding light on progress in preclinical and clinical development

INTRODUCTION

Gliomas are infiltrating brain tumors associated with high morbidity and mortality. Current standard of care includes radiation, chemotherapy, and surgical resection. Today, survival rates for malignant glioma patients remain dismal and unchanged for decades. The glioma microenvironment is highly immunosuppressive and consequently this has motivated the development of immunotherapies for counteracting this condition, enabling the immune cells within the tumor microenvironment to react against this tumor.

AREAS COVERED

The authors discuss immunotherapeutic strategies for glioma in phase-I/II clinical trials and illuminate their mechanisms of action, limitations, and key challenges. They also examine promising approaches under preclinical development.

EXPERT OPINION

In the last decade there has been an expansion in immune-mediated anti-cancer therapies. In the glioma field, sophisticated strategies have been successfully implemented in preclinical models. Unfortunately, clinical trials have not yet yielded consistent results for glioma patients. This could be attributed to our limited understanding of the complex immune cell infiltration and its interaction with the tumor cells, the selected time for treatment, the combination with other therapies and the route of administration of the agent. Applying these modalities to treat malignant glioma is challenging, but many new alternatives are emerging to by-pass these hurdles.

Characterization and antiproliferative activity of glioma-derived extracellular vesicles

Aim: To characterize a method to isolate glioma-derived extracellular vesicles (GEVs) and understand their role in immune system modulation and glioma progression. Materials & methods: GEVs were isolated by differential centrifugation from C6 cell supernatant and characterized by size and expression of CD9, HSP70, CD39 and CD73. The glioma model was performed by injecting C6 glioma cells into the right striatum of Wistar rats in the following groups: controls (C6 cells alone), coinjection (C6 cells + GEVs) and GEVs by intranasal administration followed by immune cells, tumor size and cells proliferation analyses. Results: GEVs presented uniform size (175 nm), expressed CD9, HSP70, CD39, CD73 and produced adenosine. In vivo, we observed a reduction in tumor size, in cell proliferation (Ki-67) and in a regulatory cell marker (FoxP3). Conclusion: GEVs, administered before or at tumor challenge, have antiproliferative properties and reduce regulatory cells in the glioma microenvironment.

An Update on Novel Therapeutic Warfronts of Extracellular Vesicles (EVs) in Cancer Treatment: Where We Are Standing Right Now and Where to Go in the Future

Extracellular vesicles (EVs) are a heterogeneous group of membrane-bounded vesicles that are believed to be produced and secreted by presumably all cell types under physiological and pathological conditions, including tumors. EVs are very important vehicles in intercellular communications for both shorter and longer distances and are able to deliver a wide range of cargos including proteins, lipids, and various species of nucleic acids effectively. EVs have been emerging as a novel biotherapeutic platform to efficiently deliver therapeutic cargos to treat a broad range of diseases including cancer. This vast potential of drug delivery lies in their abilities to carry a variety of cargos and their ease in crossing the biological membranes. Similarly, their presence in a variety of body fluids makes them a potential biomarker for early diagnosis, prognostication, and surveillance of cancer. Here, we discuss the relatively least and understudied aspects of EV biology and tried to highlight the obstacles and limitations in their clinical applications and also described most of the new warfronts to beat cancer at multiple stages. However, much more challenges still remain to evaluate EV-based therapeutics, and we are very much hopeful that the current work prompts further discovery.

Extracellular vesicles derived from ODN-stimulated macrophages transfer and activate Cdc42 in recipient cells and thereby increase cellular permissiveness to EV uptake

Endosomal Toll-like receptors (TLRs) mediate intracellular innate immunity via the recognition of DNA and RNA sequences. Recent work has reported a role for extracellular vesicles (EVs), known to transfer various nucleic acids, in uptake of TLR-activating molecules, raising speculation about possible roles of EVs in innate immune surveillance. Whether EV-mediated uptake is a general mechanism, however, was unresolved; and the molecular machinery that might be involved was unknown. We show that, when macrophages are stimulated with the TLR9 agonist CpG oligodeoxynucleotides (ODN), the secreted EVs transport ODN into naïve macrophages and induce the release of chemokine TNF-α. In addition, these EVs transfer Cdc42 into recipient cells, resulting in further enhancement of their cellular uptake. Transport of ODN and Cdc42 from TLR9-activated macrophages to naïve cells via EVs exerts synergetic effects in propagation of the intracellular immune response, suggesting a general mechanism of EV-mediated uptake of pathogen-associated molecular patterns.

Roles of Extracellular Vesicles in High-Grade Gliomas: Tiny Particles with Outsized Influence

High-grade gliomas, particularly glioblastomas (grade IV), are devastating diseases with dismal prognoses; afflicted patients seldom live longer than 15 months, and their quality of life suffers immensely. Our current standard-of-care therapy has remained essentially unchanged for almost 15 years, with little new therapeutic progress. We desperately need a better biologic understanding of these complicated tumors in a complicated organ. One area of rejuvenated study relates to extracellular vesicles (EVs)-membrane-enclosed nano- or microsized particles that originate from the endosomal system or are shed from the plasma membrane. EVs contribute to tumor heterogeneity (including the maintenance of glioma stem cells or their differentiation), the impacts of hypoxia (angiogenesis and coagulopathies), interactions amid the tumor microenvironment (concerning the survival of astrocytes, neurons, endothelial cells, blood vessels, the blood-brain barrier, and the ensuing inflammation), and influences on the immune system (both stimulatory and suppressive). This article reviews glioma EVs and the ways that EVs manifest themselves as autocrine, paracrine, and endocrine factors in proximal and distal intra- and intercellular communications. The reader should note that there is much controversy, and indeed confusion, in the field over the exact roles for EVs in many biological processes, and we will engage some of these difficulties herein.

Extracellular vesicles in cancer immune responses: roles of purinergic receptors

Extracellular vesicles (EVs) are nano- to micro-scale membrane-enclosed vesicles that are released from presumably all cell types. Tumor cells and immune cells are prodigious generators of EVs often with competing phenotypes in terms of immune suppression versus immune stimulation. Purinergic receptors, proteins that bind diverse purine nucleotides and nucleosides (ATP, ADP, AMP, adenosine), are widely expressed across tissues and cell types, and are prominent players in immune and tumor cell nucleotide metabolism. The effects of purinergic receptor stimulation or agonism tend to produce inflammatory responses that may aid immune stimulation but may also provoke various immune suppression mechanisms, particularly in the tumor microenvironment. EVs released by cells following receptor stimulation are frequently pro-inflammatory, but often also pro-thrombolytic; these EVs may generate an environment that favors tumor progression at the cost of an effective immune response. Purinergic signaling pathways are becoming more recognized as valuable targets in various therapeutic scenarios, including cancer. It is possible that some of those clinically relevant compounds might also impact EV secretion and/or phenotype, which would hopefully capitalize on the immune stimulatory properties of purinergic signaling while minimizing the immune suppressive consequences. This review covers a relatively understudied area in EV biology, but even so, focuses almost exclusively on the purinergic receptors in a very limited capacity. There is much more to evaluate and incorporate into our understanding of extracellular nucleotides in EV biology, and we hope this work prompts further discovery.

Exosomes in cancer: small vesicular transporters for cancer progression and metastasis, biomarkers in cancer therapeutics

Cancer progression is a polygenic procedure in which the exosomes can function as substantial roles. Exosomes are tiny, phospholipid bilayer membrane nanovesicles of endocytic derivation with a diameter of 40-100 nm. These nanovesicles can transport bioactive molecules containing mRNAs, proteins, DNA fragments, and non-coding RNAs from a donor cell to recipient cells, and cause the alteration in genetic and epigenetic factors and reprogramming of the target cells. Many diverse cell types such as mesenchymal cells, immune cells, and cancer cells can induce the release of exosomes. Increasing evidence illustrated that the exosomes derived from tumor cells might trigger the tumor initiation, tumor cell growth and progression, metastasis, and drug resistance. The secreted nanovesicles of exosomes can play significant roles in cells communicate via shuttling the nucleic acid molecules and proteins to target cells and tissues. In this review, we discussed multiple mechanisms related to biogenesis, load, and shuttle of the exosomes. Also, we illustrated the diverse roles of exosomes in several types of human cancer development, tumor immunology, angiogenesis, and metastasis. The exosomes may act as the promising biomarkers for the prognosis of various types of cancers which suggested a new pathway for anti-tumor therapeutic of these nanovesicles and promoted exosome-based cancer for clinical diagnostic and remedial procedures.

Extracellular Vesicle Heterogeneity: Subpopulations, Isolation Techniques, and Diverse Functions in Cancer Progression

Cells release membrane enclosed nano-sized vesicles termed extracellular vesicles (EVs) that function as mediators of intercellular communication by transferring biological information between cells. Tumor-derived EVs have emerged as important mediators in cancer development and progression, mainly through transfer of their bioactive content which can include oncoproteins, oncogenes, chemokine receptors, as well as soluble factors, transcripts of proteins and miRNAs involved in angiogenesis or inflammation. This transfer has been shown to influence the metastatic behavior of primary tumors. Moreover, tumor-derived EVs have been shown to influence distant cellular niches, establishing favorable microenvironments that support growth of disseminated cancer cells upon their arrival at these pre-metastatic niches. It is generally accepted that cells release a number of major EV populations with distinct biophysical properties and biological functions. Exosomes, microvesicles, and apoptotic bodies are EV populations most widely studied and characterized. They are discriminated based primarily on their intracellular origin. However, increasing evidence suggests that even within these EV populations various subpopulations may exist. This heterogeneity introduces an extra level of complexity in the study of EV biology and function. For example, EV subpopulations could have unique roles in the intricate biological processes underlying cancer biology. Here, we discuss current knowledge regarding the role of subpopulations of EVs in cancer development and progression and highlight the relevance of EV heterogeneity. The position of tetraspanins and integrins therein will be highlighted. Since addressing EV heterogeneity has become essential for the EV field, current and novel techniques for isolating EV subpopulations will also be discussed. Further dissection of EV heterogeneity will advance our understanding of the critical roles of EVs in health and disease.

The Origin and Functions of Exosomes in Cancer

Exosomes are nanovesicles having a maximum size of 150 nm and is a newly emerging focus in various fields of research. Its role in cargo trafficking along with its differential expression is associated with the disrupted homeostasis and provides an opportunity to defend against different diseases like cancer. Furthermore, exosomes are rich in cargos, which contain proteins and nucleic acids that directly reflect the metabolic state of the cells from which it originates. This review summarizes recent studies on tumor-derived exosomes with an overview about biogenesis, their functions and potential of using as diagnostic and prognostic markers. We also discussed the current challenges and microfluidic-based detection approaches that might improve the detection of exosomes in different settings. More intricate studies of the molecular mechanisms in angiogenesis, pre-metastatic niche formation, and metastasis can give more promising insights and novel strategies in oncotherapeutics.

EV, Microvesicles/MicroRNAs and Stem Cells in Cancer

The role of extracellular vesicles (EV) in carcinogenesis has become the focus of much research. These microscopic messengers have been found to regulate immune system function, particularly in tumorigenesis, as well as conditioning future metastatic sites for the attachment and growth of tumor tissue. Through an interaction with a range of host tissues, EVs are able to generate a pro-tumor environment that is essential for tumorigenesis. These small nanovesicles are an ideal candidate for a non-invasive indicator of pathogenesis and/or disease progression as they can display individualized nucleic acid, protein, and lipid expression profiles that are often reflective of disease state, and can be easily detected in bodily fluids, even after extended cryo-storage. Furthermore, the ability of EVs to securely transport signaling molecules and localize to distant tissues suggests these particles may greatly improve the delivery of therapeutic treatments, particularly in cancer. In this chapter, we discuss the role of EV in the identification of new diagnostic and prognostic cancer biomarkers, as well as the development of novel EV-based cancer therapies.

Extracellular Vesicles in Brain Tumors and Neurodegenerative Diseases

Extracellular vesicles (EVs) can be classified into apoptotic bodies, microvesicles (MVs), and exosomes, based on their origin or size. Exosomes are the smallest and best characterized vesicles which derived from the endosomal system. These vesicles are released from many different cell types including neuronal cells and their functions in the nervous system are investigated. They have been proposed as novel means for intercellular communication, which takes part not only to the normal neuronal physiology but also to the transmission of pathogenic proteins. Indeed, exosomes are fundamental to assemble and transport proteins during development, but they can also transfer neurotoxic misfolded proteins in pathogenesis. The present review will focus on their roles in neurological diseases, specifically brain tumors, such as glioblastoma (GBM), neuroblastoma (NB), medulloblastoma (MB), and metastatic brain tumors and chronic neurodegenerative diseases, such as Alzheimer, Parkinson, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington, and Prion diseseases highlighting their involvement in spreading neurotoxicity, in therapeutics, and in pathogenesis.

Macrophage type 2 differentiation in a patient with laryngeal squamous cell carcinoma and metastatic prostate adenocarcinoma to the cervical lymph nodes

Background

The tumor microenvironment often polarizes infiltrating macrophages towards a type 2, or M2 phenotype, that is characterized by expression of various cysteine-rich, scavenger receptors, including CD163. The primary function of M2 macrophages is to facilitate wound healing. As such, they are capable of providing metabolic support to a growing tumor, neovascularization, as well as protection from cytotoxic T cells. The tumor microenvironment contains a milieu of secreted factors and vesicles, which in certain circumstances can gain access to lymphatic vessels that drain to local lymph nodes.

Case presentation

We report a 59-year-old male with recurrent T4 squamous cell carcinoma (SCC) of the larynx with synchronous prostate adenocarcinoma confined to the prostate and regional pelvic lymph nodes, without metastatic disease. The patient underwent salvage total laryngectomy and bilateral neck dissection with final pathology revealing a recurrent moderately differentiated SCC involving the larynx as well as prostate cancer in draining level 4 cervical lymph nodes bilaterally. CD163 staining was performed on the primary tumor, a negative draining lymph node, and a level four lymph node with a focus of metastatic prostate cancer and compared to benign controls. The negative draining lymph node demonstrated a large CD163 population of cells as did the interface of the focus of prostate cancer and surrounding lymph node. CD163 levels were markedly increased in this patient compared to benign lymph node controls. The macrophage differentiation at the primary tumor in the larynx was strongly CD163 positive supporting an immune permissive environment for tumor growth and metastasis.

Conclusion

We describe a unique case of solitary metastatic prostate cancer to cervical lymph nodes in the setting of a laryngeal cancer. These observations suggest that SCC-derived factors drive a tumor-supportive environment in draining lymph nodes dominated by an overwhelming number of CD163+, M2 macrophages. Lymph nodes that are ‘primed’ by SCC differentiation to M2 phenotype may be at higher risk of harboring metastases.

Loss-of-function mutation in Mirta22/Emc10 rescues specific schizophrenia-related phenotypes in a mouse model of the 22q11.2 deletion

Identification of protective loss-of-function (LoF) mutations holds great promise for devising novel therapeutic interventions, although it faces challenges due to the scarcity of protective LoF alleles in the human genome. Exploiting the detailed mechanistic characterization of animal models of validated disease mutations offers an alternative. Here, we provide insights into protective-variant biology based on our characterization of a model of the 22q11.2 deletion, a strong genetic risk factor for schizophrenia (SCZ). Postnatal brain up-regulation of Mirta22/Emc10, an inhibitor of neuronal maturation, represents the major transcriptional effect of the 22q11.2-associated microRNA dysregulation. Here, we demonstrate that mice in which the Df(16)A deficiency is combined with a LoF Mirta22 allele show rescue of key SCZ-related deficits, namely prepulse inhibition decrease, working memory impairment, and social memory deficits, as well as synaptic and structural plasticity abnormalities in the prefrontal cortex. Additional analysis of homozygous Mirta22 knockout mice, in which no alteration is observed in the above-mentioned SCZ-related phenotypes, highlights the deleterious effects of Mirta22 up-regulation. Our results support a causal link between dysregulation of a miRNA target and SCZ-related deficits and provide key insights into beneficial LoF mutations and potential new treatments.

Immune Checkpoint in Glioblastoma: Promising and Challenging

Glioblastoma (GBM) is a severe malignant brain cancer with poor overall survival. Conventional intervention remains dismal to prevent recurrence and deterioration of GBM cell. Recent years have witnessed exciting breakthroughs in novel immune strategies, especially checkpoint inhibitors, some of which have become adjuvant setting after standard of care in melanoma. Several clinical trials of checkpoint inhibitors are ongoing in glioblastoma and other brain carcinomas. Plus, synergistic combinations of checkpoint inhibitors with conventional therapy strategies—radiotherapy, temozolomide, bevacizumab, and corticosteroids are now being exploited and applied in clinical settings. This review highlights the recent developments of checkpoints in GBM immunotherapy to provide a brief and comprehensive review of current treatment options. Furthermore, we will discuss challenges remained, such as unique immune system of central nervous system (CNS), immune-related toxicities, synergies, and adverse interactions of combination therapies.

How cancer cells dictate their microenvironment: present roles of extracellular vesicles

Intercellular communication plays an important role in cancer initiation and progression through secretory molecules, including growth factors and cytokines. Recent advances have revealed that small membrane vesicles, termed extracellular vesicles (EVs), served as a regulatory agent in the intercellular communication of cancer. EVs enable the transfer of functional molecules, including proteins, mRNA and microRNAs (miRNAs), into recipient cells. Cancer cells utilize EVs to dictate the unique phenotype of surrounding cells, thereby promoting cancer progression. Against such "education" by cancer cells, non-tumoral cells suppress cancer initiation and progression via EVs. Therefore, researchers consider EVs to be important cues to clarify the molecular mechanisms of cancer biology. Understanding the functions of EVs in cancer progression is an important aspect of cancer biology that has not been previously elucidated. In this review, we summarize experimental data that indicate the pivotal roles of EVs in cancer progression.

Modulation of tissue tropism and biological activity of exosomes and other extracellular vesicles: New nanotools for cancer treatment

Exosomes are naturally secreted nanovesicles that have recently aroused a great interest in the scientific and clinical community for their roles in intercellular communication in almost all physiological and pathological processes. These 30-100nm sized vesicles are released from the cells into the extracellular space and ultimately into biofluids in a tightly regulated way. Their molecular composition reflects their cells of origin, may confer specific cell or tissue tropism and underlines their biological activity. Exosomes and other extracellular vesicles (EVs) carry specific sets of proteins, nucleic acids (DNA, mRNA and regulatory RNAs), lipids and metabolites that represent an appealing source of novel noninvasive markers through biofluid biopsies. Exosome-shuttled molecules maintain their biological activity and are capable of modulating and reprogramming recipient cells. This multi-faceted nature of exosomes hold great promise for improving cancer treatment featuring them as novel diagnostic sensors as well as therapeutic effectors and drug delivery vectors. Natural biological activity including the therapeutic payload and targeting behavior of EVs can be tuned via genetic and chemical engineering. In this review we describe the properties that EVs share with conventional synthetic nanoparticles, including size, liposome-like membrane bilayer with customizable surface, and multifunctional capacity. We also highlight unique characteristics of EVs, which possibly allow them to circumvent some limitations of synthetic nanoparticle systems and facilitate clinical translation. The latter are in particular correlated with their innate stability, ability to cross biological barriers, efficiently deliver bioactive cargos or evade immune recognition. Furthermore, we discuss the potential roles for EVs in diagnostics and theranostics, and highlight the challenges that still need to be overcome before EVs can be applied to routine clinical practice.

Extracellular Vesicles in Brain Tumor Progression

Brain tumors can be viewed as multicellular 'ecosystems' with increasingly recognized cellular complexity and systemic impact. While the emerging diversity of malignant disease entities affecting brain tissues is often described in reference to their signature alterations within the cellular genome and epigenome, arguably these cell-intrinsic changes can be regarded as hardwired adaptations to a variety of cell-extrinsic microenvironmental circumstances. Conversely, oncogenic events influence the microenvironment through their impact on the cellular secretome, including emission of membranous structures known as extracellular vesicles (EVs). EVs serve as unique carriers of bioactive lipids, secretable and non-secretable proteins, mRNA, non-coding RNA, and DNA and constitute pathway(s) of extracellular exit of molecules into the intercellular space, biofluids, and blood. EVs are also highly heterogeneous as reflected in their nomenclature (exosomes, microvesicles, microparticles) attempting to capture their diverse origin, as well as structural, molecular, and functional properties. While EVs may act as a mechanism of molecular expulsion, their non-random uptake by heterologous cellular recipients defines their unique roles in the intercellular communication, horizontal molecular transfer, and biological activity. In the central nervous system, EVs have been implicated as mediators of homeostasis and repair, while in cancer they may act as regulators of cell growth, clonogenicity, angiogenesis, thrombosis, and reciprocal tumor-stromal interactions. EVs produced by specific brain tumor cell types may contain the corresponding oncogenic drivers, such as epidermal growth factor receptor variant III (EGFRvIII) in glioblastoma (and hence are often referred to as 'oncosomes'). Through this mechanism, mutant oncoproteins and nucleic acids may be transferred horizontally between cellular populations altering their individual and collective phenotypes. Oncogenic pathways also impact the emission rates, types, cargo, and biogenesis of EVs, as reflected by preliminary analyses pointing to differences in profiles of EV-regulating genes (vesiculome) between molecular subtypes of glioblastoma, and in other brain tumors. Molecular regulators of vesiculation can also act as oncogenes. These intimate connections suggest the context-specific roles of different EV subsets in the progression of specific brain tumors. Advanced efforts are underway to capture these events through the use of EVs circulating in biofluids as biomarker reservoirs and to guide diagnostic and therapeutic decisions.

Focus on Extracellular Vesicles: Development of Extracellular Vesicle-Based Therapeutic Systems

Many types of cells release phospholipid membrane vesicles thought to play key roles in cell-cell communication, antigen presentation, and the spread of infectious agents. Extracellular vesicles (EVs) carry various proteins, messenger RNAs (mRNAs), and microRNAs (miRNAs), like a “message in a bottle” to cells in remote locations. The encapsulated molecules are protected from multiple types of degradative enzymes in body fluids, making EVs ideal for delivering drugs. This review presents an overview of the potential roles of EVs as natural drugs and novel drug-delivery systems.

Serum exosomes and cytokines promote a T-helper cell type 2 environment in the peripheral blood of glioblastoma patients

BACKGROUND

Glioblastoma (GBM) is an aggressive infiltrative brain tumor with a particularly poor prognosis that is characterized by microvascular proliferation, necrotic tissue, and significant infiltration of M2-like monocytes. Compromised barrier function in tumor vasculature might be expected to permit communication between the tumor microenvironment and peripheral blood.

METHODS

To ascertain whether tumor-derived vesicles and/or factors might reach the bloodstream and what effects these molecules have on the peripheral compartment, we analyzed blood samples collected from primary GBM patients.

RESULTS

Notably, a significant number of patient sera samples contained tumor exosome-reactive immunoglobulin (Ig)G2 and IgG4 antibody isotypes, which are consistent with Th2 immunity. M2-like monocytes expressing CD14+ and CD163+, another indicator of Th2 bias, are elevated in GBM patient blood and associated with high serum concentrations of colony-stimulating factor 2 and 3, as well as interleukin-2, -4, and -13, the latter 2 cytokines being hallmarks of Th2 immunity. GBM patient sera samples induce high levels of CD163 expression when added to normal monocytes, providing mechanistic evidence of a basis for Th2 bias. Fractionation of GBM patient sera into samples enriched for exosomes or soluble factors proved that both fractions are capable of inducing CD163 expression in normal monocytes.

CONCLUSIONS

The results of the current study indicate a Th2 bias in the periphery of GBM patients, likely as a result of products elaborated by the tumor. Consequentially, through immune modulation these brain tumors exert systemic effects beyond the confines of the CNS.

Exosomes for repair, regeneration and rejuvenation

INTRODUCTION

Application of regenerative medicine strategies for repair of organs/tissue impacted by chronic disease is an active subject for product development. Such methodologies emphasize the role of stem cells as the active biological ingredient. However, recent developments in elucidating mechanisms of action of these therapies have focused on the role of paracrine, 'action-at-a-distance' modus operandi in mediating the ability to catalyze regenerative outcomes without significant site-specific engraftment. A salient component of this secreted regenerative milieu are exosomes: 40-100 nm intraluminal vesicles that mediate transfer of proteins and nucleic acids across cellular boundaries.

AREAS COVERED

Here, we synthesize recent studies from PubMed and Google Scholar highlighting how cell-based therapeutics and cosmeceutics are transitioning towards the secretome generally and exosomes specifically as a principal modulator of regenerative outcomes.

EXPERT OPINION

Exosomes contribute to organ development and mediate regenerative outcomes in injury and disease that recapitulate observed bioactivity of stem cell populations. Encapsulation of the active biological ingredients of regeneration within non-living exosome carriers may offer process, manufacturing and regulatory advantages over stem cell-based therapies.