Recent advances and future of immunotherapy for glioblastoma

Pentraxin 3: A Main Driver of Inflammation and Immune System Dysfunction in the Tumor Microenvironment of Glioblastoma

Brain tumors are a heterogeneous group of brain neoplasms that are highly prevalent in individuals of all ages worldwide. Within this pathological framework, the most prevalent and aggressive type of primary brain tumor is glioblastoma (GB), a subtype of glioma that falls within the IV-grade astrocytoma group. The death rate for patients with GB remains high, occurring within a few months after diagnosis, even with the gold-standard therapies now available, such as surgery, radiation, or a pharmaceutical approach with Temozolomide. For this reason, it is crucial to continue looking for cutting-edge therapeutic options to raise patients' survival chances. Pentraxin 3 (PTX3) is a multifunctional protein that has a variety of regulatory roles in inflammatory processes related to extracellular matrix (ECM). An increase in PTX3 blood levels is considered a trustworthy factor associated with the beginning of inflammation. Moreover, scientific evidence suggested that PTX3 is a sensitive and earlier inflammation-related marker compared to the short pentraxin C-reactive protein (CRP). In several tumoral subtypes, via regulating complement-dependent and macrophage-associated tumor-promoting inflammation, it has been demonstrated that PTX3 may function as a promoter of cancer metastasis, invasion, and stemness. Our review aims to deeply evaluate the function of PTX3 in the pathological context of GB, considering its pivotal biological activities and its possible role as a molecular target for future therapies.

Navigating the Immune Challenge in Glioblastoma: Exploring Immunotherapeutic Avenues for Overcoming Immune Suppression

Glioblastoma multiforme (GBM) is a primary brain tumor known for its short survival time, typically 14-18 months from diagnosis to fatality. Managing GBM poses significant challenges due to factors like the formidable blood-brain barrier, the immunosuppressive conditions within GBM, and the intricacies of surgical procedures. Currently, the typical treatment for GBM combines surgical procedures, radiation therapy, and chemotherapy using temozolomide. Unfortunately, this conventional approach has not proven effective in substantially extending the lives of GBM patients. Consequently, researchers are exploring alternative methods for GBM management. One promising avenue receiving attention in recent years is immunotherapy. This approach has successfully treated cancer types like non-small cell lung cancer and blood-related malignancies. Various immunotherapeutic strategies are currently under investigation for GBM treatment, including checkpoint inhibitors, vaccines, chimeric antigen receptor (CAR) T-cell therapy, and oncolytic viruses. A comprehensive review of 26 high-quality studies conducted over the past decade, involving thorough searches of databases such as PubMed and Google Scholar, has been conducted. The findings from this review suggest that while immunotherapeutic strategies show promise, they face significant limitations and challenges in practical application for GBM treatment. The study emphasizes the importance of combining diverse approaches, customizing treatments for individual patients, and ongoing research efforts to improve GBM patients' outlook.

Streptonaphthyridine A, a new naphthyridine analogue with antiproliferative activity against human glioma cells from mariana trench-associated actinomycete Streptomyces sp. SY2111

A new naphthyridine analogue, named streptonaphthyridine A (1), together with eight previously reported compounds (2-9), were isolated from a Mariana Trench sediment-associated actinomycete Streptomyces sp. SY2111. Planar structure of streptonaphthyridine A was established by analyses of its HRESIMS data and extensive NMR spectra and its absolute configuration was determined by a combination of single crystal X-ray diffraction analysis and optical rotation calculations. Streptonaphthyridine A (1) had antiproliferative activity against human glioma U87MG and U251 cells with IC₅₀ values of 7.9 ± 1.3 and 13.4 ± 2.7 µM, respectively, and the known compound monomethylsulochrin (7) showed more potent activity with IC₅₀ values of 0.6 ± 0.1 µM for U87MG cells and 0.1 ± 0.0 µM for U251 cells.

Interactions Between Anti-Angiogenic Therapy and Immunotherapy in Glioblastoma

Glioblastoma is the most aggressive brain tumor with a median survival ranging from 6.2 to 16.7 months. The complex interactions between the tumor and the cells of tumor microenvironment leads to tumor evolution which ultimately results in treatment failure. Immunotherapy has shown great potential in the treatment of solid tumors but has been less effective in treating glioblastoma. Failure of immunotherapy in glioblastoma has been attributed to low T-cell infiltration in glioblastoma and dysfunction of the T-cells that are present in the glioblastoma microenvironment. Recent advances in single-cell sequencing have increased our understanding of the transcriptional changes in the tumor microenvironment pre and post-treatment. Another treatment modality targeting the tumor microenvironment that has failed in glioblastoma has been anti-angiogenic therapy such as the VEGF neutralizing antibody bevacizumab, which did not improve survival in randomized clinical trials. Interestingly, the immunosuppressed microenvironment and abnormal vasculature of glioblastoma interact in ways that suggest the potential for synergy between these two therapeutic modalities that have failed individually. Abnormal tumor vasculature has been associated with immune evasion and the creation of an immunosuppressive microenvironment, suggesting that inhibiting pro-angiogenic factors like VEGF can increase infiltration of effector immune cells into the tumor microenvironment. Remodeling of the tumor vasculature by inhibiting VEGFR2 has also been shown to improve the efficacy of PDL1 cancer immunotherapy in mouse models of different cancers. In this review, we discuss the recent developments in our understanding of the glioblastoma tumor microenvironment specially the tumor vasculature and its interactions with the immune cells, and opportunities to target these interactions therapeutically. Combining anti-angiogenic and immunotherapy in glioblastoma has the potential to unlock these therapeutic modalities and impact the survival of patients with this devastating cancer.

Nanoparticle designs for delivery of nucleic acid therapeutics as brain cancer therapies

Glioblastoma (GBM) is an aggressive central nervous system cancer with a dismal prognosis. The standard of care involves surgical resection followed by radiotherapy and chemotherapy, but five-year survival is only 5.6% despite these measures. Novel therapeutic approaches, such as immunotherapies, targeted therapies, and gene therapies, have been explored to attempt to extend survival for patients. Nanoparticles have been receiving increasing attention as promising vehicles for non-viral nucleic acid delivery in the context of GBM, though delivery is often limited by low blood-brain barrier permeability, particle instability, and low trafficking to target brain structures and cells. In this review, nanoparticle design considerations and new advances to overcome nucleic acid delivery challenges to treat brain cancer are summarized and discussed.

Targeting Immune Modulators in Glioma While Avoiding Autoimmune Conditions

Communication signals and signaling pathways are often studied in different physiological systems. However, it has become abundantly clear that the immune system is not self-regulated, but functions in close association with the nervous system. The neural-immune interface is complex; its balance determines cancer progression, as well as autoimmune disorders. Immunotherapy remains a promising approach in the context of glioblastoma multiforme (GBM). The primary obstacle to finding effective therapies is the potent immunosuppression induced by GBM. Anti-inflammatory cytokines, induction of regulatory T cells, and the expression of immune checkpoint molecules are the key mediators for immunosuppression in the tumor microenvironment. Immune checkpoint molecules are ligand-receptor pairs that exert inhibitory or stimulatory effects on immune responses. In the past decade, they have been extensively studied in preclinical and clinical trials in diseases such as cancer or autoimmune diseases in which the immune system has failed to maintain homeostasis. In this review, we will discuss promising immune-modulatory targets that are in the focus of current clinical research in glioblastoma, but are also in the precarious position of potentially becoming starting points for the development of autoimmune diseases like multiple sclerosis.

Long Noncoding RNA NONHSAT079852.2 Contributes to GBM Recurrence by Functioning as a ceRNA for has-mir-10401-3p to Facilitate HSPA1A Upregulation

Glioblastoma multiforme (GBM) is the most common brain malignancy and major cause of high mortality in patients with GBM, and its high recurrence rate is its most prominent feature. However, the pathobiological mechanisms involved in recurrent GBM remain largely unknown. Here, whole-transcriptome sequencing (RNA-sequencing, RNA-Seq) was used in characterizing the expression profile of recurrent GBM, and the aim was to identify crucial biomarkers that contribute to GBM relapse. Differentially expressed RNAs in three recurrent GBM tissues compared with three primary GBM tissues were identified through RNA-Seq. The function and mechanism of a candidate long noncoding RNA (lncRNA) in the progression and recurrence of GBM were elucidated by performing comprehensive bioinformatics analyses, such as functional enrichment analysis, protein-protein interaction prediction, and lncRNA-miRNA-mRNA regulatory network construction, and a series of in vitro assays. As the most significantly upregulated gene identified in recurrent GBM, HSPA1A is mainly related to antigen presentation and the MAPK signaling pathway, as indicated by functional enrichment analysis. HSPA1A was predicted as the target gene of the lncRNA NONHSAT079852.2. qRT-PCR revealed that NONHSAT079852.2 was significantly elevated in recurrent GBM relative to that in primary GBM, and high NONHSAT079852.2 expression was associated with the poor overall survival rates of patients with GBM. The knockdown of NONHSAT079852.2 successfully induced tumor cell apoptosis, inhibited the proliferation, migration, invasion and the expression level of HSPA1A in glioma cells. NONHSAT079852.2 was identified to be a sponge for hsa-miR-10401-3p through luciferase reporter assay. Moreover, HSPA1A was targeted and regulated by hsa-miR-10401-3p. Collectively, the results suggested that NONHSAT079852.2 acts as a sponge of hsa-mir-10401-3p and thereby enhances HSPA1A expression, promotes tumor cell proliferation and invasion, and leads to the progression and recurrence of GBM. This study will provide new insight into the regulatory mechanisms of NONHSAT079852.2-mediated competing endogenous RNA in the pathogenesis of recurrent GBM and evidence of the potential of lncRNAs as diagnostic biomarkers or potential therapeutic targets.

A narrative review of research progress on drug therapies for glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most aggressive, common, and lethal subtype of malignant gliomas originating from the central nervous system. Currently, the standard therapy for GBM is surgical resection combined with radiation and temozolomide (TMZ). However, the treatment only improves the 2-year survival rate from 10% to 26%, accompanied by more than 90% recurrence of GBM tumors at the original site. Low survival rate, serious side effects, and poor prognosis force people to find new therapies. Recent years, the combination of clinical drugs improves the survival rate of GBM patients, but new therapeutic drugs with high-efficiency and low-toxicity are still needed to be discovered. The successful use of immunotherapy in tumor brings hope for people to explore new methods in treating GBM. While the inability to cross the blood-brain barrier (BBB), loss of lymphatic tissue drainage, and antigen-presenting cells in the central nervous system are major reasons for the failure of immunotherapy in the treatment of GBM. Glioma stem cells (GSCs) is a subtype of tumorigenic stem cells which has more specific tumorigenic potential indicating targeting GSCs may be expected to improve therapeutic efficacy. In this review, we discuss clinical drugs that have benefited patients with GBM, cancer immunotherapy for GBM, summarize new drug targets of GBM, and review strategies for increasing the passage of drugs through the BBB.

Viral Gene Therapy for Glioblastoma Multiforme: A Promising Hope for the Current Dilemma

Glioblastoma multiforme (GBM), as one of the most common malignant brain tumors, was limited in its treatment effectiveness with current options. Its invasive and infiltrative features led to tumor recurrence and poor prognosis. Effective treatment and survival improvement have always been a challenge. With the exploration of genetic mutations and molecular pathways in neuro-oncology, gene therapy is becoming a promising therapeutic approach. Therapeutic genes are delivered into target cells with viral vectors to act specific antitumor effects, which can be used in gene delivery, play an oncolysis effect, and induce host immune response. The application of engineering technology makes the virus vector used in genetics a more prospective future. Recent advances in viral gene therapy offer hope for treating brain tumors. In this review, we discuss the types and designs of viruses as well as their study progress and potential applications in the treatment of GBM. Although still under research, viral gene therapy is promising to be a new therapeutic approach for GBM treatment in the future.

Current Approaches for Glioma Gene Therapy and Virotherapy

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in the adult population and it carries a dismal prognosis. Inefficient drug delivery across the blood brain barrier (BBB), an immunosuppressive tumor microenvironment (TME) and development of drug resistance are key barriers to successful glioma treatment. Since gliomas occur through sequential acquisition of genetic alterations, gene therapy, which enables to modification of the genetic make-up of target cells, appears to be a promising approach to overcome the obstacles encountered by current therapeutic strategies. Gene therapy is a rapidly evolving field with the ultimate goal of achieving specific delivery of therapeutic molecules using either viral or non-viral delivery vehicles. Gene therapy can also be used to enhance immune responses to tumor antigens, reprogram the TME aiming at blocking glioma-mediated immunosuppression and normalize angiogenesis. Nano-particles-mediated gene therapy is currently being developed to overcome the BBB for glioma treatment. Another approach to enhance the anti-glioma efficacy is the implementation of viro-immunotherapy using oncolytic viruses, which are immunogenic. Oncolytic viruses kill tumor cells due to cancer cell-specific viral replication, and can also initiate an anti-tumor immunity. However, concerns still remain related to off target effects, and therapeutic and transduction efficiency. In this review, we describe the rationale and strategies as well as advantages and disadvantages of current gene therapy approaches against gliomas in clinical and preclinical studies. This includes different delivery systems comprising of viral, and non-viral delivery platforms along with suicide/prodrug, oncolytic, cytokine, and tumor suppressor-mediated gene therapy approaches. In addition, advances in glioma treatment through BBB-disruptive gene therapy and anti-EGFRvIII/VEGFR gene therapy are also discussed. Finally, we discuss the results of gene therapy-mediated human clinical trials for gliomas. In summary, we highlight the progress, prospects and remaining challenges of gene therapies aiming at broadening our understanding and highlighting the therapeutic arsenal for GBM.

Expression profile of ACTL8, CTCFL, OIP5 and XAGE3 in glioma and their prognostic significance: a retrospective clinical study

Cancer/testis antigens (CTAs) are attractive therapeutic targets for tumor immunotherapy due to their restrictive expression in normal testis but excessive in majority of tumor types. ACTL8, CTCFL, OIP5 and XAGE3 are members of the CTAs family. Currently, the data of ACTL8, CTCFL, OIP5 and XAGE3 expression in glioma is limited. Methods: ACTL8, CTCFL, OIP5 and XAGE3 mRAN and protein expressions were detected in 108 glioma samples by Reverse Transcriptase-PCR (RT-PCR) and immunohistochemistry and the correlations between their expressions and clinical indexes were analyzed. Furthermore, their clinical significance on glioma prognosis was determined by follow-up data. Results: The mRNA positive rate of ACTL8, CTCFL, OIP5 and XAGE3 was 15.74% (17/108), 22.22% (24/108), 13.89% (15/108) and 37.96% (41/108), respectively. At least one CTA mRNA was expressed by 61.11% of glioma tissues, while 2 or more by 29.63%. For protein expression, the positive rate of them was 21.30% (23/108), 34.26% (37/108), 19.44% (21/108) and 23.15% (25/108), respectively. At least one CTA protein was expressed by 58.33% of glioma tissues and 2 or more by 29.63%. Although there were no correlations between their mRNA expressions and clinicopathological parameters, the protein expression of ACTL8, OIP5 and XAGE3 was positively correlated with KPS; while the ACTL8 protein was correlated with gender, and OIP5 protein with gender and WHO grade. Kaplan-Meier analysis revealed a significant negative correlation between the CTCFL protein expression, combined ACTL8 and/or CTCFL protein expression and survival. Conclusions: The results suggest that the cohort of glioma does express ACTL8, CTCFL, OIP5 and XAGE3 at both mRNA and protein levels indicating glioma is CTAs-rich tumors. CTCFL protein and the combined ACTL8 and/or CTCFL protein might act as poor prognostic markers for glioma and as potential ideal combined antigens for glioma immunotherapy.

Glioblastoma Immunotherapy Targeting the Innate Immune Checkpoint CD47-SIRPα Axis

Glioblastoma Multiforme (GBM) is the most common and aggressive form of intracranial tumors with poor prognosis. In recent years, tumor immunotherapy has been an attractive strategy for a variety of tumors. Currently, most immunotherapies take advantage of the adaptive anti-tumor immunity, such as cytotoxic T cells. However, the predominant accumulation of tumor-associated microglia/macrophages (TAMs) results in limited success of these strategies in the glioblastoma. To improve the immunotherapeutic efficacy for GBM, it is detrimental to understand the role of TAM in glioblastoma immunosuppressive microenvironment. In this review, we will discuss the roles of CD47-SIRPα axis in TAMs infiltration and activities and the promising effects of targeting this axis on the activation of both innate and adaptive antitumor immunity in glioblastoma.

Current Perspectives on Therapies, Including Drug Delivery Systems, for Managing Glioblastoma Multiforme

Glioblastoma multiforme (GBM), a standout among the most dangerous class of central nervous system (CNS) cancer, is most common and is an aggressive malignant brain tumor in adults. In spite of developments in modality therapy, it remains mostly incurable. Consequently, the need for novel systems, strategies, or therapeutic approaches for enhancing the assortment of active agents meant for GBM becomes an important criterion. Currently, cancer research focuses mainly on improving the treatment of GBM via diverse novel drug delivery systems. The treatment options at diagnosis are multimodal and include radiation therapy. Moreover, significant advances in understanding the molecular pathology of GBM and associated cell signaling pathways have opened opportunities for new therapies. Innovative treatment such as immunotherapy also gives hope for enhanced survival. The objective of this work was to collect and report the recent research findings to manage GBM. The present review includes existing novel drug delivery systems and therapies intended for managing GBM. Reported novel drug delivery systems and diverse therapies seem to be precise, secure, and relatively effective, which could lead to a new track for the obliteration of GBM.

Nanomedicine-based immunotherapy for central nervous system disorders

Central nervous system (CNS) disorders represent a broad spectrum of brain ailments with short- and long-term disabilities, and nanomedicine-based approaches provide a new therapeutic approach to treating CNS disorders. A variety of potential drugs have been discovered to treat several neuronal disorders; however, their therapeutic success can be limited by the presence of the blood-brain barrier (BBB). Furthermore, unique immune functions within the CNS provide novel target mechanisms for the amelioration of CNS diseases. Recently, various therapeutic approaches have been applied to fight brain-related disorders, with moderate outcomes. Among the various therapeutic strategies, nanomedicine-based immunotherapeutic systems represent a new era that can deliver useful cargo with promising pharmacokinetics. These approaches exploit the molecular and cellular targeting of CNS disorders for enhanced safety, efficacy, and specificity. In this review, we focus on the efficacy of nanomedicines that utilize immunotherapy to combat CNS disorders. Furthermore, we detailed summarize nanomedicine-based pathways for CNS ailments that aim to deliver drugs across the BBB by mimicking innate immune actions.

Potential roads for reaching the summit: an overview on target therapies for high-grade gliomas

Background:

The tailored targeting of specific oncogenes represents a new frontier in the treatment of high-grade glioma in the pursuit of innovative and personalized approaches. The present study consists in a wide-ranging overview of the target therapies and related translational challenges in neuro-oncology.

Methods:

A review of the literature on PubMed/MEDLINE on recent advances concerning the target therapies for treatment of central nervous system malignancies was carried out. In the Medical Subject Headings, the terms “Target Therapy”, “Target drug” and “Tailored Therapy” were combined with the terms “High-grade gliomas”, “Malignant brain tumor” and “Glioblastoma”. Articles published in the last five years were further sorted, based on the best match and relevance. The ClinicalTrials.gov website was used as a source of the main trials, where the search terms were “Central Nervous System Tumor”, “Malignant Brain Tumor”, “Brain Cancer”, “Brain Neoplasms” and “High-grade gliomas”.

Results:

A total of 137 relevant articles and 79 trials were selected. Target therapies entailed inhibitors of tyrosine kinases, PI3K/AKT/mTOR pathway, farnesyl transferase enzymes, p53 and pRB proteins, isocitrate dehydrogenases, histone deacetylases, integrins and proteasome complexes. The clinical trials mostly involved combined approaches. They were phase I, II, I/II and III in 33%, 42%, 16%, and 9% of the cases, respectively.

Conclusion:

Tyrosine kinase and angiogenesis inhibitors, in combination with standard of care, have shown most evidence of the effectiveness in glioblastoma. Resistance remains an issue. A deeper understanding of the molecular pathways involved in gliomagenesis is the key aspect on which the translational research is focusing, in order to optimize the target therapies of newly diagnosed and recurrent brain gliomas. (www.actabiomedica.it)

Personalized neoantigen vaccines: a glimmer of hope for glioblastoma

INTRODUCTION

Glioblastoma multiforme (GBM) is the most prevalent primary brain tumor. In spite of the rigorous multimodal treatment involving surgery and radiochemotherapy, GBM has a dismal prognosis and rapid relapsing potential. Hence, search for novel therapeutic agents still continues. Neoantigens are the tumor-specific antigens which arise due to somatic mutations in the tumor genome. In recent years, personalized vaccine approach targeting neoantigens has been explored widely in cancer immunotherapy and several efforts have also been made to revolutionize the immunotherapy of cold tumors such as GBM using neoantigen targeted vaccines.

AREAS COVERED

In this review, we discuss the clinical application of personalized neoantigen targeted vaccine strategy in GBM immunotherapy. While discussing this strategy, we brief about the current challenges faced in GBM treatment by the novel immunotherapeutics.

EXPERT OPINION

To date, very few vaccines developed for GBM have reached till phase III clinical development. Early-phase clinical trials of GBM neoantigen vaccines have shown promising clinical outcomes and therefore, its rapid clinical development is warranted. Advent of newer and faster techniques such as next-generation sequencing will drive the faster clinical development of multiplex neoantigen vaccines and hence, increase in the clinical trials is expected.

Endoscopic third ventriculostomy with choroid plexus cauterization for the treatment of infantile hydrocephalus in Haiti

OBJECTIVE

Untreated hydrocephalus poses a significant health risk to children in the developing world. In response to this risk, global neurosurgical efforts have increasingly focused on endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) in the management of infantile hydrocephalus in low- and middle-income countries (LMICs). Here, the authors report their experience with ETV/CPC at the Hospital Bernard-Mevs/Project Medishare (HBMPM) in Port-au-Prince, Haiti.

METHODS

The authors conducted a retrospective review of a series of consecutive children who had undergone ETV/CPC for hydrocephalus over a 1-year period at HBMPM. The primary outcome of interest was time to ETV/CPC failure. Univariate and multivariate analyses using a Cox proportional hazards regression were performed to identify preoperative factors that were associated with outcomes.

RESULTS

Of the 82 children who underwent ETV/CPC, 52.2% remained shunt free at the last follow-up (mean 6.4 months). On univariate analysis, the ETV success score (ETVSS; p = 0.002), success of the attempted ETV (p = 0.018), and bilateral CPC (p = 0.045) were associated with shunt freedom. In the multivariate models, a lower ETVSS was independently associated with a poor outcome (HR 0.072, 95% CI 0.016-0.32, p < 0.001). Two children (2.4%) died of postoperative seizures.

CONCLUSIONS

As in other LMICs, ETV/CPC is an effective treatment for hydrocephalus in children in Haiti, with a low but significant risk profile. Larger multinational prospective databases may further elucidate the ideal candidate for ETV/CPC in resource-poor settings.

High Dimensional Mass Cytometry Analysis Reveals Characteristics of the Immunosuppressive Microenvironment in Diffuse Astrocytomas

The tumor immune microenvironment (TIME) plays a pivotal role in tumor development, progression, and prognosis. However, the characteristics of the TIME in diffuse astrocytoma (DA) are still unclear. Leveraging mass cytometry with a panel of 33 markers, we analyzed the infiltrating immune cells from 10 DA and 4 oligodendroglioma (OG) tissues and provided a single cell-resolution landscape of the intricate immune microenvironment. Our study profiled the composition of the TIME in DA and confirmed the presence of immune cells, such as glioma-associated microglia/macrophages (GAMs), CD8+ T cells, CD4+ T cells, regulatory T cells (Tregs), and natural killer cells. Increased percentages of PD-1+ CD8+ T cells, TIM-3+ CD4+ T cell subpopulations, Tregs and pro-tumor phenotype GAMs substantially contribute to the local immunosuppressive microenvironment in DA. DAs and OGs share similar compositions in terms of immune cells, while GAMs in DA exhibit more inhibitory characteristics than those in OG.

Sensory changes and lipoprotein ratios in patients with brain cancers during cancer-related therapy: A prospective cross-sectional study

AIM

To identify the sensory changes and lipoprotein ratios and their relationship in brain cancer patients during cancer-related therapy (CRT).

METHODS

This was a prospective cross-sectional study with three observation times: before CRT, at 2-3 weeks, and 4-6 weeks after beginning CRT. The changes in patients' symptoms were evaluated using the Memorial Symptom Assessment Scale, and lipoprotein ratios were measured using total cholesterol/ high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol/HDL-c, and triglyceride/HDL-c at the three time points.

RESULTS

Sensory changes such as itching, swelling of the arms and legs, numbness in the hands or feet, tingling in the hands or feet, and changes in the way food tastes and lipoprotein ratios were altered in patients with brain cancer during CRT. The lipoprotein ratios showed a significant positive correlation with sensory changes at each observation time (p < .05).

CONCLUSION

Sensory changes and lipoprotein ratios varied, and their significant relationship was identified during CRT. Lipoprotein ratios should be considered as an indicator for symptom management in patients with malignant brain cancer during CRT.

Imaging-guided precision medicine in glioblastoma patients treated with immune checkpoint modulators: research trend and future directions in the field of imaging biomarkers and artificial intelligence

Immunotherapies that employ immune checkpoint modulators (ICMs) have emerged as an effective treatment for a variety of solid cancers, as well as a paradigm shift in the treatment of cancers. Despite this breakthrough, the median survival time of glioblastoma patients has remained at about 2 years. Therefore, the safety and anti-cancer efficacy of combination therapies that include ICMs are being actively investigated. Because of the distinct mechanisms of ICMs, which restore the immune system’s anti-tumor capacity, unconventional immune-related phenomena are increasingly being reported in terms of tumor response and progression, as well as adverse events. Indeed, immunotherapy response assessments for neuro-oncology (iRANO) play a central role in guiding cancer patient management and define a “wait and see strategy” for patients treated with ICMs in monotherapy with progressive disease on MRI. This article deciphers emerging research trends to ameliorate four challenges unaddressed by the iRANO criteria: (1) patient selection, (2) identification of immune-related phenomena other than pseudoprogression (i.e., hyperprogression, the abscopal effect, immune-related adverse events), (3) response assessment in combination therapies including ICM, and (4) alternatives to MRI. To this end, our article provides a structured approach for standardized selection and reporting of imaging modalities to enable the use of precision medicine by deciphering the characteristics of the tumor and its immune environment. Emerging preclinical or clinical innovations are also discussed as future directions such as immune-specific targeting and implementation of artificial intelligence algorithms.

Identification of Tumor Antigens Among the HLA Peptidomes of Glioblastoma Tumors and Plasma

Glioblastoma multiforme (GBM) is the most aggressive brain tumor with poor prognosis to most patients. Immunotherapy of GBM is a potentially beneficial treatment option, whose optimal implementation may depend on familiarity with tumor specific antigens, presented as HLA peptides by the GBM cells. Further, early detection of GBM, such as by a routine blood test, may improve survival, even with the current treatment modalities. This study includes large-scale analyses of the HLA peptidome (immunopeptidome) of the plasma-soluble HLA molecules (sHLA) of 142 plasma samples, and the membranal HLA of GBM tumors of 10 of these patients' tumor samples. Tumor samples were fresh-frozen immediately after surgery and the plasma samples were collected before, and at multiple visits after surgery. In total, this HLA peptidome analysis involved 52 different HLA allotypes and resulted in the identification of more than 35,000 different HLA peptides. Strong correlations were observed in the signal intensities and in the repertoires of identified peptides between the tumors and plasma-soluble HLA peptidomes of the individual patients, whereas low correlations were observed between these HLA peptidomes and the tumors' proteomes. HLA peptides derived from Cancer/Testis Antigens (CTAs) were selected based on their presence among the HLA peptidomes of the patients and absence of expression of their source genes from any healthy and essential human tissues, except from immune-privileged sites. Additionally, peptides were selected as potential biomarkers if their levels in the plasma-sHLA peptidome were significantly reduced after the removal of tumor mass. The CTAs identified among the analyzed HLA peptidomes provide new opportunities for personalized immunotherapy and for early diagnosis of GBM.

Changing paradigms for targeted therapies against diffuse infiltrative gliomas: tackling a moving target

Introduction: Gliomas are highly heterogeneous primary brain tumors which result in a disproportionately high degree of morbidity and mortality despite their locoregional occurrence. Advances in the understanding of the biological makeup of these malignancies have yielded a number of potential tumor-driving pathways which have been identified as rational targets for therapy. However, early trials of agents that target these pathways have uniformly failed to yield improvement in outcomes in patients with malignant gliomas. Areas covered: This review provides an overview of the most common biological features of gliomas and the strategies to target the same; in addition, the current status of immunotherapy and biological therapies are outlined and the future directions to tackle the challenges of therapy for gliomas are examined. Expert opinion: The limitations of current treatments are attributed to the inability of most of these agents to cross the blood-brain barrier and to the intrinsic heterogeneity of the tumors that result in treatment resistance. The recent emergence of immune-mediated and biological therapies and of agents that target metabolic pathways in gliomas have provided strategies that may overcome tumor heterogeneity and ongoing trials of such agents are anticipated to yield improved outcomes.

Sigma-2 receptor/TMEM97 agonist PB221 as an alternative drug for brain tumor

Background

There are limited effective drugs that can reach the brain to target brain tumors, in particular glioblastoma, which is one of the most difficult cancers to be cured from. Because the overexpression of the sigma-2 receptor is frequently reported in glioma clinical samples and associated with poor prognosis and malignancy, we herein studied the anti-tumor effect of the sigma-2 receptor agonist PB221 (4-cyclohexyl-1-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperidine) on an anaplastic astrocytoma tumor model based on previous encouraging results in pancreatic cancer and neuroblastoma SK-N-SH cells.

Methods

The expression of the sigma-2 receptor, transmembrane protein 97 (TMEM97), in ALTS1C1 and UN-KC6141 cell lines was measured by RT-PCR and quantitative RT-PCR. The binding of sigma-2 receptor fluorescent ligands PB385 (6-[5-[3-(4-cyclohexylpiperazin-1-yl)propyl]-5,6,7,8-tetrahydronaphthalen-5-yloxy]-N-(7-nitro-2,1,3-benzoxadiazol-4-yl)hexanamine) and NO1 (2-{6-[2-(3-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)propyl)-3,4-dihydroisoquinolin-1(2H)-one-5-yloxy]hexyl}-5-(dimethylamino)isoindoline-1,3-dione) was examined by flow cytometry and the fluorescent plate reader. The antitumor activity of PB221 was initially examined in the murine brain tumor cell line ALTS1C1 and then in the murine pancreatic cell line UN-KC6141. The potential therapeutic efficacy of PB221 for murine brain tumors was examined by in vitro migration and invasion assays and in vivo ectopic and orthotopic ALTS1C1 tumor models.

Results: The IC₅₀ of PB221 for ALTS1C1 and UN-KC6141 cell lines was 10.61 ± 0.96 and 13.13 ± 1.15 μM, respectively. A low dose of PB221 (1 μM) significantly repressed the migration and invasion of ALTS1C1 cells, and a high dose of PB221 (20 μM) resulted in the apoptotic cell death of ALTS1C1 cells. These effects were reduced by the lipid antioxidant α-tocopherol, but not by the hydrophilic N-acetylcysteine, suggesting mitochondrial oxidative stress is involved. The in vivo study revealed that PB221 effectively retarded tumor growth to 36% of the control tumor volume in the ectopic intramuscular tumor model and increased the overall survival time by 20% (from 26 to 31 days) in the orthotopic intracerebral tumor model.

Conclusions

This study demonstrates that the sigma-2 receptor agonist PB221 has the potential to be an alternative chemotherapeutic drug for brain tumors with comparable side effects as the current standard-of-care drug, temozolomide.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5700-7) contains supplementary material, which is available to authorized users.

Novel Immunotherapeutics for Treatment of Glioblastoma: The Last Decade of Research

Despite surgical resection and adjuvant chemoradiation, survival for glioblastoma remains poor. Because of the dismal prognosis, attention has shifted to alternative adjuvant treatment modalities. Although traditionally limited to systemic malignancies (melanoma, lung and colon cancer), the field of immunotherapy has recently identified glioblastoma as a potential target for new treatments. Anti-tumor vaccines (dendritic cell/heat shock), checkpoint inhibitors, chimeric T-cell receptors, and virotherapy all have been preliminarily trialed in glioblastoma patients with reasonable success and safety. Although there are certainly limitations due to autoimmune reactions and immune escape, immunotherapeutics hold much promise in the future treatment paradigms for malignant glioma.

Acid-Induced Activated Cell-Penetrating Peptide-Modified Cholesterol-Conjugated Polyoxyethylene Sorbitol Oleate Mixed Micelles for pH-Triggered Drug Release and Efficient Brain Tumor Targeting Based on a Charge Reversal Mechanism

Glioblastoma multiforme is the most devastating malignant brain tumor in adults. Even with the standard care of therapy, the prognosis remains dismal due to tumor heterogeneity, tumor infiltration, and, more importantly, the restrictive nature of the blood-brain barrier (BBB). To overcome the challenge of effectively delivering therapeutic cargo into the brain, herein a "smart", multifunctional polymeric micelle was developed using a cholesterol-conjugated polyoxyethylene sorbitol oleate. A cell-penetrating peptide, arginine-glycine repeats (RG)₅, was incorporated into the micelles to improve cellular uptake, while a pH-sensitive masking sequence, histidine-glutamic acid repeats (HE)₅, was introduced for charge shielding to minimize nonspecific binding and uptake at physiological pH. Results demonstrated that (RG)₅- and (HE)₅-modified mixed micelles were optimized using this strategy to effectively mask the cationic charges of the activated cell-penetrating peptide (RG)₅ at physiological pH, i.e., limiting internalization, and were selectively triggered in response to a mildly acidic microenvironment in vitro based on a charge reversal mechanism. In vivo results further confirmed that such micelles preferentially accumulated in both brain and tumor tissues in both xenograft and orthotropic glioma mouse models. Furthermore, micelles significantly inhibited tumor growth with limited toxicity to peripheral tissues. The combination of BBB penetration, tumor targeting, potent efficacy, and high tolerance of these micelles strongly suggests that they could be a promising candidate for safe and effective drug delivery to the brain.

Immunogenetics of glioblastoma: the future of personalized patient management

The prognosis of glioblastoma has changed little over the past two decades, with only minor improvements in length of overall survival through the addition of temozolomide (temodal) to standard of care and the recommended use of alternating electric field therapy (optune) to newly diagnosed patients. In an effort to define novel therapeutic targets across molecularly heterogeneous disease subgroups, researchers have begun to uncover the complex interplay between epigenetics, cell signaling, metabolism, and the immunosuppressive tumor microenvironment. Indeed, IDH mutations are now recognized as a defining differential factor not only influencing global hypermethylation and patient prognosis but also degree of immune infiltration within individual tumors. Likewise, next-generation sequencing has defined subgroup-specific transcriptional profiles that correlate with different mechanisms of immune evasion, including increased PD-L1 and CTLA-4 among mesenchymal tumors. Interestingly, sequencing of the T cell repertoire from numerous patient samples suggests that the correlation between mutational burden and enrichment of tumor-specific peptides may be less convincing than originally suspected. While this raises questions over the efficacy of dendritic cell or tumor-lysate vaccines and CAR-T therapies, these avenues continue to be explored. In addition to these active immunotherapies, inhibitors of molecular hubs with wide reaching effects, including STAT3, IDO, and TGF-β, are now in early-phase clinical trials. With the potential to block intrinsic biological properties of tumor growth and invasion while bolstering the immunogenic profile of the tumor microenvironment, these new targets represent a new direction for GBM therapies. In this review, we show the advances in molecular profiling and immunophenotyping of GBM, which may lead to the development of new personalized therapeutic strategies.

Identification of Tumor Antigens Among the HLA Peptidomes of Glioblastoma Tumors and Plasma

Glioblastoma multiforme (GBM) is the most aggressive brain tumor with poor prognosis to most patients. Immunotherapy of GBM is a potentially beneficial treatment option, whose optimal implementation may depend on familiarity with tumor specific antigens, presented as HLA peptides by the GBM cells. Furthermore, early detection of GBM, such as by a routine blood test, may improve survival, even with the current treatment modalities. This study includes large-scale analyses of the HLA peptidome (immunopeptidome) of the plasma-soluble HLA molecules (sHLA) of 142 plasma samples, and the membranal HLA of GBM tumors of 10 of these patients' tumor samples. Tumor samples were fresh-frozen immediately after surgery and the plasma samples were collected before, and at multiple visits after surgery. In total, this HLA peptidome analysis involved 52 different HLA allotypes and resulted in the identification of more than 35,000 different HLA peptides. Strong correlations were observed in the signal intensities and in the repertoires of identified peptides between the tumors and plasma-soluble HLA peptidomes of the individual patients, whereas low correlations were observed between these HLA peptidomes and the tumors' proteomes. HLA peptides derived from Cancer/Testis Antigens (CTAs) were selected based on their presence among the HLA peptidomes of the patients and absence of expression of their source genes from any healthy and essential human tissues, except from immune-privileged sites. Additionally, peptides were selected as potential biomarkers if their levels in the plasma-sHLA peptidome were significantly reduced after the removal of tumor mass. The CTAs identified among the analyzed HLA peptidomes provide new opportunities for personalized immunotherapy and for early diagnosis of GBM.

Therapeutic efficacy of specific immunotherapy for glioma: a systematic review and meta-analysis

Although different immunotherapeutic approaches have been developed for the treatment of glioma, there is a discrepancy between clinical trials limiting their approval as common treatment. So, the current systematic review and meta-analysis were conducted to assess survival and clinical response of specific immunotherapy in patients with glioma. Generally, seven databases were searched to find eligible studies. Controlled clinical trials investigating the efficacy of specific immunotherapy in glioma were found eligible. After data extraction and risk of bias assessment, the data were analyzed based on the level of heterogeneity. Overall, 25 articles with 2964 patients were included. Generally, mean overall survival did not statistically improve in immunotherapy [median difference=1.51; 95% confidence interval (CI)=-0.16-3.17; p=0.08]; however, it was 11.16 months higher in passive immunotherapy (95% CI=5.69-16.64; p<0.0001). One-year overall survival was significantly higher in immunotherapy groups [hazard ratio (HR)=0.69; 95% CI=0.52-0.92; p=0.01]. As the hazard rate in the immunotherapy approach was 0.83 of the control group, 2-year overall survival was significantly higher in immunotherapy (HR=0.83; 95% CI=0.69-0.99; p=0.04). Three-year overall survival was significantly higher in immunotherapy as well (HR=0.67; 95% CI=0.48-0.92; p=0.01). Overall, median progression-free survival was significantly higher in immunotherapy (standard median difference=0.323; 95% CI=0.110-0.536; p=0.003). However, 1-year progression-free survival was not remarkably different between immunotherapy and control groups (HR=0.94; 95% CI=0.74-1.18; p=0.59). Specific immunotherapy demonstrated remarkable improvement in survival of patients with glioma and could be a considerable choice of treatment in the future. Despite the current promising results, further high-quality randomized controlled trials are required to approve immunotherapeutic approaches as the standard of care and the front-line treatment for glioma.

Receptor-Targeted Glial Brain Tumor Therapies

Among primary brain tumors, malignant gliomas are notably difficult to manage. The higher-grade tumors represent an unmet need in medicine. There have been extensive efforts to implement receptor-targeted therapeutic approaches directed against gliomas. These approaches include immunotherapies, such as vaccines, adoptive immunotherapy, and passive immunotherapy. Targeted cytotoxic radio energy and pro-drug activation have been designed specifically for brain tumors. The field of targeting through receptors progressed significantly with the discovery of an interleukin 13 receptor alpha 2 (IL-13RA2) as a tumor-associated receptor over-expressed in most patients with glioblastoma (GBM) but not in normal brain. IL-13RA2 has been exploited in novel experimental therapies with very encouraging clinical responses. Other receptors are specifically over-expressed in many patients with GBM, such as EphA2 and EphA3 receptors, among others. These findings are important in view of the heterogeneity of GBM tumors and multiple tumor compartments responsible for tumor progression and resistance to therapies. The combined targeting of multiple receptors in different tumor compartments should be a preferred way to design novel receptor-targeted therapeutic approaches in gliomas.

Glioblastoma Treatments: An Account of Recent Industrial Developments

The different drugs and medical devices, which are commercialized or under industrial development for glioblastoma treatment, are reviewed. Their different modes of action are analyzed with a distinction being made between the effects of radiation, the targeting of specific parts of glioma cells, and immunotherapy. Most of them are still at a too early stage of development to firmly conclude about their efficacy. Optune, which triggers antitumor activity by blocking the mitosis of glioma cells under the application of an alternating electric field, seems to be the only recently developed therapy with some efficacy reported on a large number of GBM patients. The need for early GBM diagnosis is emphasized since it could enable the treatment of GBM tumors of small sizes, possibly easier to eradicate than larger tumors. Ways to improve clinical protocols by strengthening preclinical studies using of a broader range of different animal and tumor models are also underlined. Issues related with efficient drug delivery and crossing of blood brain barrier are discussed. Finally societal and economic aspects are described with a presentation of the orphan drug status that can accelerate the development of GBM therapies, patents protecting various GBM treatments, the different actors tackling GBM disease, the cost of GBM treatments, GBM market figures, and a financial analysis of the different companies involved in the development of GBM therapies.

Activation of the Receptor Tyrosine Kinase AXL Regulates the Immune Microenvironment in Glioblastoma

Glioblastoma (GBM) is a lethal disease with no effective therapies available. We previously observed upregulation of the TAM (Tyro-3, Axl, and Mer) receptor tyrosine kinase family member AXL in mesenchymal GBM and showed that knockdown of AXL induced apoptosis of mesenchymal, but not proneural, glioma sphere cultures (GSC). In this study, we report that BGB324, a novel small molecule inhibitor of AXL, prolongs the survival of immunocompromised mice bearing GSC-derived mesenchymal GBM-like tumors. We show that protein S (PROS1), a known ligand of other TAM receptors, was secreted by tumor-associated macrophages/microglia and subsequently physically associated with and activated AXL in mesenchymal GSC. PROS1-driven phosphorylation of AXL (pAXL) induced NFκB activation in mesenchymal GSC, which was inhibited by BGB324 treatment. We also found that treatment of GSC-derived mouse GBM tumors with nivolumab, a blocking antibody against the immune checkpoint protein PD-1, increased intratumoral macrophages/microglia and activation of AXL. Combinatorial therapy with nivolumab plus BGB324 effectively prolonged the survival of mice bearing GBM tumors. Clinically, expression of AXL or PROS1 was associated with poor prognosis for patients with GBM. Our results suggest that the PROS1-AXL pathway regulates intrinsic mesenchymal signaling and the extrinsic immune microenvironment, contributing to the growth of aggressive GBM tumors.Significance: These findings suggest that development of combination treatments of AXL and immune checkpoint inhibitors may provide benefit to patients with GBM. Cancer Res; 78(11); 3002-13. ©2018 AACR.

Therapeutic Potential of Thymoquinone in Glioblastoma Treatment: Targeting Major Gliomagenesis Signaling Pathways

Glioblastoma multiforme (GBM) is one of the most devastating brain tumors with median survival of one year and presents unique challenges to therapy because of its aggressive behavior. Current treatment strategy involves surgery, radiotherapy, immunotherapy, and adjuvant chemotherapy even though optimal management requires a multidisciplinary approach and knowledge of potential complications from both the disease and its treatment. Thymoquinone (TQ), the main bioactive component of Nigella sativa L., has exhibited anticancer effects in numerous preclinical studies. Due to its multitargeting nature, TQ interferes in a wide range of tumorigenic processes and counteract carcinogenesis, malignant growth, invasion, migration, and angiogenesis. TQ can specifically sensitize tumor cells towards conventional cancer treatments and minimize therapy-associated toxic effects in normal cells. Its potential to enter brain via nasal pathway due to volatile nature of TQ adds another advantage in overcoming blood-brain barrier. In this review, we summarized the potential role of TQ in different signaling pathways in GBM that have undergone treatment with standard therapeutic modalities or with TQ. Altogether, we suggest further comprehensive evaluation of TQ in preclinical and clinical level to delineate its implied utility as novel therapeutics to combat the challenges for the treatment of GBM.

Novel Immunotherapeutics for the Treatment of Glioblastoma: The Last Decade of Research

Despite surgical resection and adjuvant chemoradiation, survival for glioblastoma remains poor. Because of the dismal prognosis, attention has shifted to alternative adjuvant treatment modalities. Although traditionally limited to systemic malignancies (melanoma, lung and colon cancer), the field of immunotherapy has recently identified glioblastoma as a potential target for new treatments. Anti-tumor vaccines (dendritic cell/heat shock), checkpoint inhibitors, chimeric T-cell receptors, and virotherapy all have been preliminarily trialed in glioblastoma patients with reasonable success and safety. Although there are limitations due to autoimmune reactions and immune escape, immunotherapeutics hold much promise in the future treatment paradigms for malignant glioma.

New extracellular factors in glioblastoma multiforme development: neurotensin, growth differentiation factor-15, sphingosine-1-phosphate and cytomegalovirus infection

Recent years have seen considerable progress in understanding the biochemistry of cancer. For example, more significance is now assigned to the tumor microenvironment, especially with regard to intercellular signaling in the tumor niche which depends on many factors secreted by tumor cells. In addition, great progress has been made in understanding the influence of factors such as neurotensin, growth differentiation factor-15 (GDF-15), sphingosine-1-phosphate (S1P), and infection with cytomegalovirus (CMV) on the 'hallmarks of cancer' in glioblastoma multiforme. Therefore, in the present work we describe the influence of these factors on the proliferation and apoptosis of neoplastic cells, cancer stem cells, angiogenesis, migration and invasion, and cancer immune evasion in a glioblastoma multiforme tumor. In particular, we discuss the effect of neurotensin, GDF-15, S1P (including the drug FTY720), and infection with CMV on tumor-associated macrophages (TAM), microglial cells, neutrophil and regulatory T cells (T_reg), on the tumor microenvironment. In order to better understand the role of the aforementioned factors in tumoral processes, we outline the latest models of intratumoral heterogeneity in glioblastoma multiforme. Based on the most recent reports, we discuss the problems of multi-drug therapy in treating glioblastoma multiforme.

Anti-glioma Natural Products Downregulating Tumor Glycolytic Enzymes from Marine Actinomycete Streptomyces sp. ZZ406

Marine natural products are important resources for discovering novel anticancer drugs. In this study, an extract prepared from the culture of a sea anemone-derived actinomycete Streptomyces sp. ZZ406 in soluble starch and casein-related liquid medium was found to have activity in inhibiting the proliferation of glioma cells and reducing the production of lactate in glioma cells. Chemical investigation of this active crude extract resulted in the isolation of four new compounds and seven known ones. Structures of the new compounds were determined by a combination of extensive NMR analyses, HRESIMS and MS-MS data, electronic circular dichroism calculation, chemical degradation, and Marfey's method. New compound 1 showed potent activity against the proliferation of different glioma cells with IC₅₀ values of 4.7 to 8.1 μM, high selectivity index (>12.3 to 21.3), and good stability in human liver microsomes. Western blot analysis revealed that compound 1 remarkably downregulated the expressions of several important glioma glycolytic enzymes. The data from this study suggested that compound 1 might have potential as a novel anti-glioma agent to be further investigated.

Glioblastoma update: molecular biology, diagnosis, treatment, response assessment, and translational clinical trials

This is an exciting time in neuro-oncology. Discoveries elucidating the molecular mechanisms of oncogenesis and the molecular subtypes of glioblastoma multiforme (GBM) have led to new diagnostic and classification schemes with more prognostic power than histology alone. Molecular profiling has become part of the standard neuropathological evaluation of GBM. Chemoradiation followed by adjuvant temozolomide remains the standard therapy for newly diagnosed GBM, but survival remains unsatisfactory. Patients with recurrent GBM continue to have a dismal prognosis, but neuro-oncology centers with active clinical trial programs are seeing a small but increasing cadre of patients with longer survival. Molecularly targeted therapeutics, personalized therapy based on molecular profiling of individual tumors, and immunotherapeutic strategies are all being evaluated and refined in clinical trials. Understanding of the molecular mechanisms of tumor-mediated immunosuppression, and specifically interactions between tumor cells and immune effector cells in the tumor microenvironment, has led to a new generation of immunotherapies, including vaccine and immunomodulatory strategies as well as T-cell-based treatments. Molecularly targeted therapies, chemoradiation, immunotherapies, and anti-angiogenic therapies have created the need to develop more reliable neuroimaging criteria for differentiating the effects of therapy from tumor progression and changes in blood–brain barrier physiology from treatment response. Translational clinical trials for patients with GBM now incorporate quantitative imaging using both magnetic resonance imaging and positron emission tomography techniques. This update presents a summary of the current standards for therapy for newly diagnosed and recurrent GBM and highlights promising translational research.

Overcoming the Host Immune Response to Adeno-Associated Virus Gene Delivery Vectors: The Race Between Clearance, Tolerance, Neutralization, and Escape

Immune responses in gene therapy with adeno-associated virus (AAV) vectors have been the object of almost two decades of study. Although preclinical models helped to define and predict certain aspects of interactions between the vector and the host immune system, most of our current knowledge has come from clinical trials. These studies have allowed development of effective interventions for modulating immunotoxicities associated with vector administration, resulting in therapeutic advances. However, the road to full understanding and effective modulation of immune responses in gene therapy is still long; the determinants of the balance between tolerance and immunogenicity in AAV vector-mediated gene transfer are not fully understood, and effective solutions for overcoming preexisting neutralizing antibodies are still lacking. However, despite these challenges, the goal of reliably delivering effective gene-based treatments is now in sight.

Chimeric antigen receptor T-cell therapy for glioblastoma

Chimeric antigen receptor (CAR) T-cell therapy has shown great promise in the treatment of hematological disease, and its utility for treatment of solid tumors is beginning to unfold. Glioblastoma continues to portend a grim prognosis and immunotherapeutic approaches are being explored as a potential treatment strategy. Identification of appropriate glioma-associated antigens, barriers to cell delivery, and presence of an immunosuppressive microenvironment are factors that make CAR T-cell therapy for glioblastoma particularly challenging. However, insights gained from preclinical studies and ongoing clinical trials indicate that CAR T-cell therapy will continue to evolve and likely become integrated with current therapeutic strategies for malignant glioma.

Rare Polyene-polyol Macrolides from Mangrove-derived Streptomyces sp. ZQ4BG

Bioactive natural products from mangrove-derived actinomycetes are important sources for discovery of drug lead compounds. In this study, an extract prepared from culture of an actinomycete Streptomyces sp. ZQ4BG isolated from mangrove soils was found to have activity in inhibiting proliferation of glioma cells. Large culture of this mangrove actinomycete in Gause’s liquid medium resulted in isolation of seven novel polyene-polyol macrolides, named as flavofungins III–IX (3–9), together with known flavofungins I (1) and II (2) and spectinabilin (10). Structures of these isolated compounds were elucidated by extensive NMR analyses and HRESIMS data. The stereochemical assignments were achieved by a combination of NOE information, universal NMR database, and chemical reactions including preparation of acetonide derivatives and Mosher esters. Flavofungins IV–VIII (4–8) are rare 32-membered polyene-polyol macrolides with a tetrahydrofuran ring, while flavofungin IX (9) represents the first example of this type of macrolide with a unique oxepane ring. Flavofungins I (1) and II (2) and spectinabilin (10) showed anti-glioma and antifungal activities.

Identification of repaglinide as a therapeutic drug for glioblastoma multiforme

Glioblastoma multiforme (GBM) is a highly aggressive brain tumor with a median survival time of only 14 months after treatment. It is urgent to find new therapeutic drugs that increase survival time of GBM patients. To achieve this goal, we screened differentially expressed genes between long-term and short-term survived GBM patients from Gene Expression Omnibus database and found gene expression signature for the long-term survived GBM patients. The signaling networks of all those differentially expressed genes converged to protein binding, extracellular matrix and tissue development as revealed in BiNGO and Cytoscape. Drug repositioning in Connectivity Map by using the gene expression signature identified repaglinide, a first-line drug for diabetes mellitus, as the most promising novel drug for GBM. In vitro experiments demonstrated that repaglinide significantly inhibited the proliferation and migration of human GBM cells. In vivo experiments demonstrated that repaglinide prominently prolonged the median survival time of mice bearing orthotopic glioma. Mechanistically, repaglinide significantly reduced Bcl-2, Beclin-1 and PD-L1 expression in glioma tissues, indicating that repaglinide may exert its anti-cancer effects via apoptotic, autophagic and immune checkpoint signaling. Taken together, repaglinide is likely to be an effective drug to prolong life span of GBM patients.

MRI in Glioma Immunotherapy: Evidence, Pitfalls, and Perspectives

Pseudophenomena, that is, imaging alterations due to therapy rather than tumor evolution, have an important impact on the management of glioma patients and the results of clinical trials. RANO (response assessment in neurooncology) criteria, including conventional MRI (cMRI), addressed the issues of pseudoprogression after radiotherapy and concomitant chemotherapy and pseudoresponse during antiangiogenic therapy of glioblastomas (GBM) and other gliomas. The development of cancer immunotherapy forced the identification of further relevant response criteria, summarized by the iRANO working group in 2015. In spite of this, the unequivocal definition of glioma progression by cMRI remains difficult particularly in the setting of immunotherapy approaches provided by checkpoint inhibitors and dendritic cells. Advanced MRI (aMRI) may in principle address this unmet clinical need. Here, we discuss the potential contribution of different aMRI techniques and their indications and pitfalls in relation to biological and imaging features of glioma and immune system interactions.

Covalent nano delivery systems for selective imaging and treatment of brain tumors

Nanomedicine is a rapidly evolving form of therapy that holds a great promise for superior drug delivery efficiency and therapeutic efficacy than conventional cancer treatment. In this review, we attempt to cover the benefits and the limitations of current nanomedicines with special attention to covalent nano conjugates for imaging and drug delivery in the brain. The improvement in brain tumor treatment remains dismal despite decades of efforts in drug development and patient care. One of the major obstacles in brain cancer treatment is the poor drug delivery efficiency owing to the unique blood-brain barrier (BBB) in the CNS. Although various anti-cancer agents are available to treat tumors outside of the CNS, the majority fails to cross the BBB. In this regard, nanomedicines have increasingly drawn attention due to their multi-functionality and versatility. Nano drugs can penetrate BBB and other biological barriers, and selectively accumulate in tumor cells, while concurrently decreasing systemic toxicity.

Immune infiltration of tumor microenvironment following immunotherapy for glioblastoma multiforme

Autologous dentritic cell immunotherapy has been proven effective in treating tumors outside the central nervous system. Current evidence from phase I and II trials suggest a similar efficacy for central nervous system tumors as well and that an active immune response against these tumors can be generated. We aim to review the literature to identify the types of immune responses against gliomas found to be generated by dendritic cell vaccinations and the types of immune cells subsequently infiltrating the glioma microenvironment. A systematic review of the literature was performed by searching the online databases PubMEd, Google Scholar, and EMBASE with use of the keywords intratumoral, infiltration, lymphocytic, vaccination and gliomas. Seven studies reporting lymphocytic infiltration of gliomas microenvironment were identified. Three studies (42.8%) reported presence of tumor infiltrating lymphocytes in 50%, 50% and 28.6% of included patients respectively in the post-vaccination specimens that were not present in the pre-vaccination samples. The remaining 4 (57.2%) reported an up to 6-fold increase in the number of pre-existing lymphocytes following vaccination. Present data indicate that tumor infiltration by lymphocytes can be induced by dentritic cell immunotherapy and that this may positively affect clinical outcome. It still remains unclear which factors influence the above reaction and therefore prediction of response to treatment is still not possible.

Single vs. combination immunotherapeutic strategies for glioma

INTRODUCTION

Malignant gliomas are highly invasive tumors, associated with a dismal survival rate despite standard of care, which includes surgical resection, radiotherapy and chemotherapy with temozolomide (TMZ). Precision immunotherapies or combinations of immunotherapies that target unique tumor-specific features may substantially improve upon existing treatments. Areas covered: Clinical trials of single immunotherapies have shown therapeutic potential in high-grade glioma patients, and emerging preclinical studies indicate that combinations of immunotherapies may be more effective than monotherapies. In this review, the authors discuss emerging combinations of immunotherapies and compare efficacy of single vs. combined therapies tested in preclinical brain tumor models. Expert opinion: Malignant gliomas are characterized by a number of factors which may limit the success of single immunotherapies including inter-tumor and intra-tumor heterogeneity, intrinsic resistance to traditional therapies, immunosuppression, and immune selection for tumor cells with low antigenicity. Combination of therapies which target multiple aspects of tumor physiology are likely to be more effective than single therapies. While a limited number of combination immunotherapies are described which are currently being tested in preclinical and clinical studies, the field is expanding at an astounding rate, and endless combinations remain open for exploration.

Peptide-22 and Cyclic RGD Functionalized Liposomes for Glioma Targeting Drug Delivery Overcoming BBB and BBTB

Chemotherapy outcomes for the treatment of glioma remain unsatisfied due to the inefficient drug transport across BBB/BBTB and poor drug accumulation in the tumor site. Nanocarriers functionalized with different targeting ligands are considered as one of the most promising alternatives. However, few studies were reported to compare the targeting efficiency of the ligands and develop nanoparticles to realize BBB/BBTB crossing and brain tumor targeting simultaneously. In this study, six peptide-based ligands (Angiopep-2, T7, Peptide-22, c(RGDfK), D-SP5 and Pep-1), widely used for brain delivery, were selected to decorate liposomes, respectively, so as to compare their targeting ability to BBB or BBTB. Based on the in vitro cellular uptake results on BCECs and HUVECs, Peptide-22 and c(RGDfK) were picked to construct a BBB/BBTB dual-crossing, glioma-targeting liposomal drug delivery system c(RGDfK)/Pep-22-DOX-LP. In vitro cellular uptake demonstrated that the synergetic effect of c(RGDfK) and Peptide-22 could significantly increase the internalization of liposomes on U87 cells. In vivo imaging further verified that c(RGDfK)/Pep-22-LP exhibited higher brain tumor distribution than single ligand modified liposomes. The median survival time of glioma-bearing mice treated with c(RGDfK)/Pep-22-DOX-LP (39.5 days) was significantly prolonged than those treated with free doxorubicin or other controls. In conclusion, the c(RGDfK) and Peptide-22 dual-modified liposome was constructed based on the targeting ability screening of various ligands. The system could effectively overcome BBB/BBTB barriers, target to tumor cells and inhibit the growth of glioma, which proved its potential for improving the efficacy of chemotherapeutics for glioma therapy.