Dendritic cell-based vaccine for the treatment of malignant glioma: a systematic review

Efficacy and Safety of Vaccines After Conventional Treatments for Survival of Gliomas: A Systematic Review and Meta-Analysis

Background

Malignant gliomas are known with poor prognosis and low rate of survival among brain tumors. Resection surgery is followed by chemotherapy and radiotherapy in treatment of gliomas which is known as the conventional treatment. However, this treatment method results in low survival rate. Vaccination has been suggested as a type of immunotherapy to increase survival rate of glioma patients. Different types of vaccines have been developed that are mainly classified in two groups including peptide vaccines and cell-based vaccines. However, there are still conflicts about which type of vaccines is more efficient for malignant glioma treatment.

Methods

Phase Ⅰ/Ⅱ clinical trials which compared the efficacy and safety of various vaccines with conventional treatments were searched in databases through November 2022. Overall survival (OS) rate, progression free survival (PFS), and OS duration were used for calculation of pooled risk ratio (RR). In addition, fatigue, headache, nausea, diarrhea, and flu-like syndrome were used for evaluating the safety of vaccines therapy in glioma patients.

Results

A total of twelve articles were included in the present meta-analysis. Comparison of OS rate between vaccinated groups and control groups who underwent only conventional treatments showed a significant increase in OS rate in vaccinated patients (I2 = 0%, RR = 11.17, 95% CI: 2.460-50.225). PFS rate was better in vaccinated glioma patients (I2 = 83%, RR = 2.87, 95% CI: 1.63-5.03). Assessment of safety demonstrated that skin reaction (I2 = 0.0%, RR = 3.654; 95% CI: 1.711-7.801, p-value = 0.0058) and flu-like syndrome were significantly more frequent adverse effects win vaccinated groups compared to the control group. Subgroup analysis also showed that vaccination leads to better OS duration in recurrent gliomas than primary gliomas, and in LGG than HGG (p-value = 0). On the other hand, personalized vaccines showed better OS duration than non-personalized vaccines (p-value = 0).

Conclusion

Vaccination is a type of immunotherapy which shows promising efficacy in treatment of malignant glioma patients in terms of OS, PFS and duration of survival. In addition, AFTV, peptide, and dendritic cell-based vaccines are among the most efficient vaccines for gliomas. Personalized vaccines also showed considerable efficacy for glioma treatments.

Brain Delivery of Biomimetic Phosphorus Dendrimer/Antibody Nanocomplexes for Enhanced Glioma Immunotherapy via Immune Modulation of T Cells and Natural Killer Cells

Fully mobilizing the activities of multiple immune cells is crucial to achieve the desired tumor immunotherapeutic efficacy yet still remains challenging. Herein, we report a nanomedicine formulation based on phosphorus dendrimer (termed AK128)/programmed cell death protein 1 antibody (aPD1) nanocomplexes (NCs) that are camouflaged with M1-type macrophage cell membranes (M1m) for enhanced immunotherapy of orthotopic glioma. The constructed AK128-aPD1@M1m NCs with a mean particle size of 160.3 nm possess good stability and cytocompatibility. By virtue of the decorated M1m having α4 and β1 integrins, the NCs are able to penetrate the blood-brain barrier to codeliver both AK128 with intrinsic immunomodulatory activity and aPD1 to the orthotopic glioma with prolonged blood circulation time. We show that the phosphorus dendrimer AK128 can boost natural killer (NK) cell proliferation in peripheral blood mononuclear cells, while the delivered aPD1 enables immune checkpoint blockade (ICB) to restore the cytotoxic T cells and NK cells, thus promoting tumor cell apoptosis and simultaneously decreasing the tumor distribution of regulatory T cells vastly for improved glioma immunotherapy. The developed nanomedicine formulation with a simple composition achieves multiple modulations of immune cells by utilizing the immunomodulatory activity of nanocarrier and antibody-mediated ICB therapy, providing an effective strategy for cancer immunotherapy.

Methods behind oncolytic virus-based DC vaccines in cancer: Toward a multiphase combined treatment strategy for Glioblastoma (GBM) patients

Glioblastoma (GBM) remains an orphan cancer disease with poor outcome. Novel treatment strategies are needed. Immunotherapy has several modes of action. The addition of active specific immunotherapy with dendritic cell vaccines resulted in improved overall survival of patients. Integration of DC vaccination within the first-line combined treatment became a challenge, and immunogenic cell death immunotherapy during chemotherapy was introduced. We used a retrospective analysis using real world data to evaluate the complex combined treatment, which included individualized multimodal immunotherapy during and after standard of care, and which required adaptations during treatment, and found a further improvement of overall survival. We also discuss the use of real world data as evidence. Novel strategies to move the field of individualized multimodal immunotherapy forward for GBM patients are reviewed.

Clinical Effects of Immuno-Oncology Therapy on Glioblastoma Patients: A Systematic Review

The most prevalent and deadly primary malignant glioma in adults is glioblastoma (GBM), which has a median survival time of about 15 months. Despite the standard of care for glioblastoma, which includes gross total resection, high-dose radiation, and temozolomide chemotherapy, this tumor is still one of the most aggressive and difficult to treat. So, it is critical to find more potent therapies that can help glioblastoma patients have better clinical outcomes. Additionally, the prognosis for recurring malignant gliomas is poor, necessitating the need for innovative therapeutics. Immunotherapy is a rather new treatment for glioblastoma and its effects are not well studied when it is combined with standard chemoradiation therapy. We conducted this study to evaluate different glioblastoma immunotherapy approaches in terms of feasibility, efficacy, and safety. We conducted a computer-assisted literature search of electronic databases for essays that are unique, involve either prospective or retrospective research, and are entirely written and published in English. We examined both observational data and randomized clinical trials. Eighteen studies met the criteria for inclusion. In conclusion, combining immunotherapy with radiochemotherapy and tumor removal is generally possible and safe, and rather effective in the prolongation of survival measures.

Glioma diagnosis and therapy: Current challenges and nanomaterial-based solutions

Glioma is often referred to as one of the most dreadful central nervous system (CNS)-specific tumors with rapidly-proliferating cancerous glial cells, accounting for nearly half of the brain tumors at an annual incidence rate of 30-80 per a million population. Although glioma treatment remains a significant challenge for researchers and clinicians, the rapid development of nanomedicine provides tremendous opportunities for long-term glioma therapy. However, several obstacles impede the development of novel therapeutics, such as the very tight blood-brain barrier (BBB), undesirable hypoxia, and complex tumor microenvironment (TME). Several efforts have been dedicated to exploring various nanoformulations for improving BBB permeation and precise tumor ablation to address these challenges. Initially, this article briefly introduces glioma classification and various pathogenic factors. Further, currently available therapeutic approaches are illustrated in detail, including traditional chemotherapy, radiotherapy, and surgical practices. Then, different innovative treatment strategies, such as tumor-treating fields, gene therapy, immunotherapy, and phototherapy, are emphasized. In conclusion, we summarize the article with interesting perspectives, providing suggestions for future glioma diagnosis and therapy improvement.

Synergy between TMZ and individualized multimodal immunotherapy to improve overall survival of IDH1 wild-type MGMT promoter-unmethylated GBM patients

The prognosis of IDH1 wild-type MGMT promoter-unmethylated GBM patients remains poor. Addition of Temozolomide (TMZ) to first-line local treatment shifted the median overall survival (OS) from 11.8 to 12.6 months. We retrospectively analyzed the value of individualized multimodal immunotherapy (IMI) to improve OS in these patients. All adults meeting the criteria and treated 06/2015-06/2021 were selected. Thirty-two patients (12f, 20m) had a median age of 47 y (range 18-69) and a KPI of 70 (50-100). Extent of resection was complete (11), <complete (12) or not documented (9). Seven patients were treated with surgery/radio(chemo)therapy and subsequent IMI (Group-1); 25 patients were treated with radiochemotherapy followed by maintenance TMZ plus IMI during and after TMZ (Group-2). Age, KPI and extent of resection were not different amongst both groups. The median OS of group-1 patients was 11 m (2 y OS: 0%). Surprisingly the median OS of group-2 patients was 22 m with 2 y OS of 36% (CI95%: 16-57), which was significantly (Log-rank: p = 0.0001) different from group-1. The data suggest that addition of IMI after local therapy on its own has no relevant effect on OS in these GBM patients, similar to maintenance TMZ. However, the combination of both TMZ + IMI significantly improved OS.

Dendritic Cell-Targeted Therapies to Treat Neurological Disorders

Dendritic cells (DCs) are the immune system's highly specialized antigen-presenting cells. When DCs are sluggish and mature, self-antigen presentation results in tolerance; however, when pathogen-associated molecular patterns stimulate mature DCs, antigen presentation results in the development of antigen-specific immunity. DCs have been identified in various vital organs of mammals (e.g., the skin, heart, lungs, intestines, and spleen), but the brain has long been thought to be devoid of DCs in the absence of neuroinflammation. However, neuroinflammation is becoming more recognized as a factor in a variety of brain illnesses. DCs are present in the brain parenchyma in trace amounts under healthy circumstances, but their numbers rise during neuroinflammation. New therapeutics are being developed that can reduce dendritic cell immunogenicity by inhibiting pro-inflammatory cytokine production and T cell co-stimulatory pathways. Additionally, innovative ways of regulating dendritic cell growth and differentiation and harnessing their tolerogenic capability are being explored. Herein, we described the function of dendritic cells in neurological disorders and discussed the potential for future therapeutic techniques that target dendritic cells and dendritic cell-related targets in the treatment of neurological disorders.

Pharmacological strategies for improving the prognosis of glioblastoma

Introduction: Treatments for brain cancer have radically evolved in the past decade due to a better understanding of the interplay between the immune system and tumors of the central nervous system (CNS). However, glioblastoma multiforme (GBM) remains the most common and lethal CNS malignancy affecting adults.Areas covered: The authors review the literature on glioblastoma pharmacologic therapies with a focus on trials of combination chemo-/immunotherapies and drug delivery platforms from 2015 to 2021.Expert opinion: Few therapeutic advances in GBM treatment have been made since the Food and Drug Administration (FDA) approval of the BCNU-eluting wafer, Gliadel, in 1996 and oral temozolomide (TMZ) in 2005. Recent advances in our understanding of GBM have promoted a wide assortment of new therapeutic approaches including combination therapy, immunotherapy, vaccines, and Car T-cell therapy along with developments in drug delivery. Given promising preclinical data, these novel pharmacotherapies for the treatment of GBM are currently being evaluated in various stages of clinical trials.

Nanomedicine-mediated optimization of immunotherapeutic approaches in cervical cancer

Cervical cancer shows immense complexity at the epigenetic, genetic and cellular levels, limiting conventional treatment. Immunotherapy has revolutionized nanomedicine and rejuvenated the field of tumor immunology. Although several immunotherapeutic approaches have shown favorable clinical responses, their efficacies vary, with subsets of patients benefitting. The success of cancer immunotherapy requires the enhancement of cytokines and antitumor effector cell production and activation. Recently, the feasibility of nanoparticle-based cytokine approaches in tumor immunotherapy has been highlighted. Immunotherapeutic nanoparticle-based platforms form a novel strategy enabling researchers to co-deliver immunomodulatory agents, target tumors, improve pharmacokinetics and minimize collateral toxicity to healthy cells. This review looks at the potential of immunotherapy and nanotechnologically enhanced immunotherapeutic approaches for cervical cancer.

Randomized Controlled Immunotherapy Clinical Trials for GBM Challenged

Simple Summary

Although multiple meta-analyses on active specific immunotherapy treatment for glioblastoma multiforme (GBM) have demonstrated a significant prolongation of overall survival, no single research group has succeeded in demonstrating the efficacy of this type of treatment in a prospective, double-blind, placebo-controlled, randomized clinical trial. In this paper, we explain how the complexity of the tumor biology and tumor–host interactions make proper stratification of a control group impossible. The individualized characteristics of advanced therapy medicinal products for immunotherapy contribute to heterogeneity within an experimental group. The dynamics of each tumor and in each patient aggravate comparative stable patient groups. Finally, combinations of immunotherapy strategies should be integrated with first-line treatment. We illustrate the complexity of a combined first-line treatment with individualized multimodal immunotherapy in a group of 70 adults with GBM and demonstrate that the integration of immunogenic cell death treatment within maintenance chemotherapy followed by dendritic cell vaccines and maintenance immunotherapy might provide a step towards improving the overall survival rate of GBM patients.

Abstract

Immunotherapies represent a promising strategy for glioblastoma multiforme (GBM) treatment. Different immunotherapies include the use of checkpoint inhibitors, adoptive cell therapies such as chimeric antigen receptor (CAR) T cells, and vaccines such as dendritic cell vaccines. Antibodies have also been used as toxin or radioactive particle delivery vehicles to eliminate target cells in the treatment of GBM. Oncolytic viral therapy and other immunogenic cell death-inducing treatments bridge the antitumor strategy with immunization and installation of immune control over the disease. These strategies should be included in the standard treatment protocol for GBM. Some immunotherapies are individualized in terms of the medicinal product, the immune target, and the immune tumor–host contact. Current individualized immunotherapy strategies focus on combinations of approaches. Standardization appears to be impossible in the face of complex controlled trial designs. To define appropriate control groups, stratification according to the Recursive Partitioning Analysis classification, MGMT promotor methylation, epigenetic GBM sub-typing, tumor microenvironment, systemic immune functioning before and after radiochemotherapy, and the need for/type of symptom-relieving drugs is required. Moreover, maintenance of a fixed treatment protocol for a dynamic, deadly cancer disease in a permanently changing tumor–host immune context might be inappropriate. This complexity is illustrated using our own data on individualized multimodal immunotherapies for GBM. Individualized medicines, including multimodal immunotherapies, are a rational and optimal yet also flexible approach to induce long-term tumor control. However, innovative methods are needed to assess the efficacy of complex individualized treatments and implement them more quickly into the general health system.

Assessment of the efficacy of passive cellular immunotherapy for glioma patients

To evaluate the therapeutic efficacy of passive cellular immunotherapy for glioma, a total of 979 patients were assigned to the meta-analysis. PubMed and the Cochrane Central Register of Controlled Trials were searched initially from February 2018 and updated in April 2019. The overall survival (OS) rates and Karnofsky performance status (KPS) values of patients who underwent passive cellular immunotherapy were compared to those of patients who did not undergo immunotherapy. The proportion of survival rates was also evaluated in one group of clinical trials. Pooled analysis was performed with random- or fixed-effects models. Clinical trials of lymphokine-activated killer cells, cytotoxic T lymphocytes, autologous tumor-specific T lymphocytes, chimeric antigen receptor T cells, cytokine-induced killer cells, cytomegalovirus-specific T cells, and natural killer cell therapies were selected. Results showed that treatment of glioma with passive cellular immunotherapy was associated with a significantly improved 0.5-year OS (p = 0.003) as well as improved 1-, 1.5-, and 3-year OS (p ≤ 0.05). A meta-analysis of 206 patients in one group of clinical trials with 12-month follow-up showed that the overall pooled survival rate was 37.9% (p = 0.003). Analysis of KPS values demonstrated favorable results for the immunotherapy arm (p < 0.001). Thus, the present meta-analysis showed that passive cellular immunotherapy prolongs survival and improves quality of life for glioma patients, suggesting that it has some clinical benefits.

Efficacy and safety of dendritic cell vaccines for patients with glioblastoma: A meta-analysis of randomized controlled trials

BACKGROUND

Dendritic cell (DC)-based vaccination has been suggested to be promising for glioblastoma. However, the evidence in randomized controlled trials (RCTs) is inconsistent. We aimed to systematically evaluate the efficacy and safety of DC vaccine for glioblastoma via a meta-analysis of RCTs.

METHODS

Related randomized controlled trials (RCTs) were identified via a search of PubMed, Embase, and Cochrane's Library. We used a random-effect model to pool the results.

RESULTS

Six phase II RCTs with 347 patients with newly diagnosed or recurrent glioblastoma that underwent conventional treatments were included. Compared to the control group with placebo or blank treatment, DC vaccine was associated with significantly improved overall survival in patients with glioblastoma (hazard ratio [HR]: 0.69, 95% confidence interval [CI]: 0.49 to 0.97, p = 0.03) with moderate heterogeneity (p for Cochrane's Q test = 0.07, I² = 51%). A trend of improved progression-free survival was also detected in patients allocated to the DC vaccine group compared to those in the control group (HR: 0.76, 95% CI: 0.56 to 1.02, p = 0.07), with no significant heterogeneity (I² = 0%). Moreover, the incidence of adverse events was not significant between patients treated with DC vaccine or control (odds ratio = 1.52, 95% CI: 0.88 to 2.62, p = 0.14; I² = 0%).

CONCLUSIONS

Evidence based on phase II RCTs suggests that DC vaccine may improve the survival of patients with glioblastoma. Large-scale RCTs are needed to validate the findings and determine the optimal regimens for DC vaccine.

Recent Advances in Oncolytic Virotherapy and Immunotherapy for Glioblastoma: A Glimmer of Hope in the Search for an Effective Therapy?

To date, no targeted drugs, antibodies or combinations of chemotherapeutics have been demonstrated to be more efficient than temozolomide, or to increase efficacy of standard therapy (surgery, radiotherapy, temozolomide, steroid dexamethasone). According to recent phase III trials, standard therapy may ensure a median overall survival of up to 18⁻20 months for adult patients with newly diagnosed glioblastoma. These data explain a failure of positive non-controlled phase II trials to predict positive phase III trials and should result in revision of the landmark Stupp trial as a historical control for median overall survival in non-controlled trials. A high rate of failures in clinical trials and a lack of effective chemotherapy on the horizon fostered the development of conceptually distinct therapeutic approaches: dendritic cell/peptide immunotherapy, chimeric antigen receptor (CAR) T-cell therapy and oncolytic virotherapy. Recent early phase trials with the recombinant adenovirus DNX-2401 (Ad5-delta24-RGD), polio-rhinovirus chimera (PVSRIPO), parvovirus H-1 (ParvOryx), Toca 511 retroviral vector with 5-fluorocytosine, heat shock protein-peptide complex-96 (HSPPC-96) and dendritic cell vaccines, including DCVax-L vaccine, demonstrated that subsets of patients with glioblastoma/glioma may benefit from oncolytic virotherapy/immunotherapy (>3 years of survival after treatment). However, large controlled trials are required to prove efficacy of next-generation immunotherapeutics and oncolytic vectors.

Efficacy and safety analysis on dendritic cell-based vaccine-treated high-grade glioma patients: a systematic review and meta-analysis

Background

Dendritic cell (DC)-based vaccine is a promising therapy for high-grade gliomas (HGGs); however, its actual effectiveness still remains controversial. This meta-analysis aims to extensively evaluate the efficacy and safety of DC vaccine for HGG patients.

Methods

We systematically searched PubMed, the Cochrane Library, EMBASE, Medline, and Web of Science for relevant parallel randomized controlled trials (RCTs) and properly controlled non-randomized studies (NRS) published in English. Two investigators reviewed all the texts and extracted information regarding overall survival (OS), progression-free survival (PFS), and adverse events (AEs) from eligible studies. Sensitivity analyses and subgroup analyses were also conducted.

Results

Of 353 suitable studies, 13 studies (three RCTs and ten NRS) involving 944 patients were finally included. Compared to the control therapy group (CT group), the DC group showed better OS and PFS without serious AEs. Subgroup analysis showed that trials designed as NRS obtained better results in the DC group in this study; however, no specific subgroup regarding dosages, cycles or injection routes was found to be superior in the DC group compared to the CT group.

Conclusion

DC vaccine can significantly improve OS and PFS, with acceptable toxicity, of HGG patients. Nevertheless, further studies are needed to verify this conclusion.

A Dendritic Cell-Targeted Adenoviral Vector Facilitates Adaptive Immune Response Against Human Glioma Antigen (CMV-IE) and Prolongs Survival in a Human Glioma Tumor Model

Antitumor immunotherapeutic strategies represent an especially promising set of approaches with rapid translational potential considering the dismal clinical context of high-grade gliomas. Dendritic cells (DCs) are the body's most professional antigen-presenting cells, able to recruit and activate T cells to stimulate an adaptive immune response. In this regard, specific loading of tumor-specific antigen onto dendritic cells potentially represents one of the most advanced strategies to achieve effective antitumor immunization. In this study, we developed a DC-specific adenoviral (Ad) vector, named Ad5scFvDEC205FF, targeting the DC surface receptor, DEC205. In vitro analysis shows that 60% of DCs was infected by this vector while the infectivity of other control adenoviral vectors was less than 10%, demonstrating superior infectivity on DCs. Moreover, an average of 14% of DCs were infected by Ad5scFvDEC205FF-GFP, while less than 3% of non-DCs were infected following in vivo administration, demonstrating highly selective in vivo DC infection. Importantly, vaccination with this vehicle expressing human glioma-specific antigen, Ad5scFvDEC205FF-CMV-IE, shows a prolonged survival benefit in GL261CMV-IE-implanted murine glioma models (p < 0.0007). Furthermore, when rechallenged, cancerous cells were completely rejected. In conclusion, our novel, viral-mediated, DC-based immunization approach has the significant therapeutic potential for patients with high-grade gliomas.

Predictors of Response to Autologous Dendritic Cell Therapy in Glioblastoma Multiforme

Background

Glioblastoma (GBM) is the most common and lethal primary malignant glioma in adults. Dendritic cell (DC) vaccines have demonstrated promising results in GBM clinical trials. However, some patients do not respond well to DC therapy, with survival rates similar to those of conventional therapy. We retrospectively analyzed clinical and laboratory data to evaluate the factors affecting vaccine treatment.

Methods

Forty-seven patients with de novo GBM were enrolled at China Medical University Hospital between 2005 and 2010 and divided into two subgroups. One subgroup of 27 patients received postsurgical adjuvant immunotherapy with autologous dendritic cell/tumor antigen vaccine (ADCTA) in conjunction with conventional treatment of concomitant chemoradiotherapy (CCRT) with temozolomide. The other 20 patients received only postsurgical conventional treatment without immunotherapy. Immunohistochemistry for CD45, CD4, CD8, programed death ligand 1 (PD-L1), and programed death 1 (PD-1) was performed on sections of surgical tumor specimens and peripheral blood mononuclear cells (PBMCs). Pearson's correlation, Cox proportional hazard model, and Kaplan-Meier analyses were performed to examine the correlations between the prognostic factors and survival rates.

Results

Younger age (<57 years), gross total resection, and CCRT and PD-1⁺ lymphocyte counts were significant prognostic factors of overall survival (OS) and progression-free survival (PFS) in the ADCTA group. Sex, CD45⁺ lymphocyte count, CD4⁺ or CD8⁺ lymphocyte count, tumor PD-L1 expression, isocitrate dehydrogenase 1 mutation, and O6 methylguanine-DNA methyltransferase promoter methylation status were not significant factors in both groups. In the ADCTA group, patients with tumor-infiltrating lymphocytes (TILs) with a lower PD-1⁺/CD8⁺ ratio (≤0.21) had longer OS and PFS (median OS 60.97 months, P < 0.001 and PFS 11.2 months, P < 0.008) compared to those with higher PD-1⁺/CD8⁺ ratio (>0.21) (median OS 20.07 months, P < 0.001 and PFS 4.43 months, P < 0.008). Similar results were observed in patients' PBMCs; lymphocyte counts with lower PD-1⁺/CD8⁺ ratio (≤0.197) had longer OS and PFS. There was a significant correlation of PD-1⁺/CD8⁺ ratio between TILs and PBMCs (Pearson's correlation R² = 0.6002, P < 0.001). By contrast, CD4^-, CD8^-, but PD-1⁺, CD45⁺ tumor-infiltrating lymphocytes have no impact on OS and PFS (P = 0.073 and P = 0.249, respectively).

Conclusion

For patients receiving DC vaccine adjuvant therapy, better outcomes are predicted in patients with younger age, with TILs or PBMCs with lower PD-1⁺/CD8⁺ ratio, with gross tumor resection, and receiving CCRT.

Evolutionary basis of a new gene- and immune-therapeutic approach for the treatment of malignant brain tumors: from mice to clinical trials for glioma patients

Glioma cells are one of the most aggressive and malignant tumors. Following initial surgery, and radio-chemotherapy they progress rapidly, so that patients' median survival remains under two years. They invade throughout the brain, which makes them difficult to treat, and are universally lethal. Though total resection is always attempted it is not curative. Standard of care in 2016 comprises surgical resection, radiotherapy and chemotherapy (temozolomide). Median survival is currently ~14-20months post-diagnosis though it can be higher in high complexity medical university centers, or during clinical trials. Why the immune system fails to recognize the growing brain tumor is not completely understood. We believe that one reason for this failure is that the brain lacks cells that perform the role that dendritic cells serve in other organs. The lack of functional dendritic cells from the brain causes the brain to be deficient in priming systemic immune responses to glioma antigens. To overcome this drawback we reconstituted the brain immune system for it to initiate and prime anti-glioma immune responses from within the brain. To achieve brain immune reconstitution adenoviral vectors are injected into the resection cavity or remaining tumor. One adenoviral vector expresses the HSV-1 derived thymidine kinase which converts ganciclovir into phospho-ganciclovir which becomes cytotoxic to dividing cells. The second adenovirus expresses the cytokine fms-like tyrosine kinase 3 ligand (Flt3L). Flt3L differentiates precursors into dendritic cells and acts as a chemokine for dendritic cells. This results in HSV-1/ganciclovir killing of tumor cells, and the release of tumor antigens, which are then taken up by dendritic cells recruited to the brain tumor microenvironment by Flt3L. Concomitant release of HMGB1, a TLR2 agonist that activates dendritic cells, stimulates dendritic cells loaded with glioma antigens to migrate to the cervical lymph nodes to prime a systemic CD8+ T cytotoxic killing of brain tumor cells. This induced immune response causes glioma-specific cytotoxicity, induces immunological memory, and does not cause brain toxicity or autoimmunity. A Phase I Clinical Trial, to test our hypothesis in human patients, was opened in December 2013 (see: NCT01811992, Combined Cytotoxic and Immune-Stimulatory Therapy for Glioma, at ClinicalTrials.gov). This trial is a first in human trial to test whether the re-engineering of the brain immune system can serve to treat malignant brain tumors. The long and winding road from the laboratory to the clinical trial follows below.

Effect and molecular mechanism of mTOR inhibitor rapamycin on temozolomide-induced autophagic death of U251 glioma cells

Glioma is a malignant tumor of the glial tissue that is difficult to excise through surgery, with poor patient prognosis. The use of chemotherapeutic drugs alone to treat glioma following surgery results in a high probability of sequelae, such as tumor recurrence. The present study investigated the effects of a novel treatment combination on glioma cells and determined the molecular mechanisms underlying its action. The effect of temozolomide (TMZ) combined with rapamycin (RAPA) on the TMZ-induced autophagic death of U251 glioma cells was examined. The U251 cell line was treated with TMZ combined with RAPA, and the cell survival rate and half maximal inhibitory concentration (IC₅₀) of TMZ/RAPA was detected using the Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was used to detect changes in cell cycle distribution. The formation of acidic vesicular organelles (AVOs) in the cytoplasm was identified using fluorescence microscopy and quantitatively analyzed. Western blotting was performed to detect the expression levels of autophagy-associated proteins Beclin-1 and microtubule associated protein 1 light chain 3 alpha (MAP1LC3A)-I and II. RAPA (1.25 nM) combined with 5 µM TMZ markedly inhibited U251 cell growth. RAPA reinforced TMZ-induced autophagic death, reducing the IC₅₀ value of treatment when combined (TMZ alone, 22.5±3.23 µM vs. TMZ and RAPA, 10.35±2.81 µM). Compared with the control group, the proportion of cells in G₂/M were markedly increased following treatment with TMZ combined with RAPA. Acridine orange staining demonstrated that TMZ combined with RAPA could markedly enhance the generation of intracellular AVOs compared with TMZ or RAPA alone. In addition, Beclin-1 and LC3-II protein expression was markedly increased compared with the control and single treatment groups (P<0.05). The results of the present study indicate that RAPA reinforces TMZ-induced autophagic death of U251 glioma cells, providing a novel therapeutic combination for the treatment of malignant glioma.

The development of dendritic cell vaccine-based immunotherapies for glioblastoma

In this review, we focus on the biologic advantages of dendritic cell-based vaccinations as a therapeutic strategy for cancer as well as preclinical and emerging clinical data associated with such approaches for glioblastoma patients.

[Immunotherapy in brain tumors]

Diffuse gliomas represent the most common primary central nervous system (CNS) tumors in adults and children alike. Glioblastoma is the most frequent and malignant form of diffuse glioma with a median overall survival of 15 months despite aggressive treatments. New therapeutic approaches are needed to prolong survival in this always fatal disease. The CNS has been considered for a long time as an immune privileged organ, in part because of the existence of the blood-brain barrier. Nonetheless, immunotherapy is a novel approach in the therapeutic management of glioma patients, which has shown promising results in several clinical trials, especially in the adult population. Vaccination, with or without dendritic cells, blockade of the immune checkpoints, and adoptive T cell transfer are the most studied modalities of diffuse glioma immunotherapy. The future most likely resides in combinatorial approaches, with administration of conventional treatments (surgery, radiochemotherapy) and immunotherapy following yet to determine schedules.

Advances in immunotherapy for the treatment of glioblastoma

Glioblastoma (GBM) is an aggressive brain tumour, associated with extremely poor prognosis and although there have been therapeutic advances, treatment options remain limited. This review focuses on the use of immunotherapy, harnessing the power of the host's immune system to reject cancer cells. Key challenges in glioma specific immunotherapy as with many other cancers are the limited immunogenicity of the cancer cells and the immunosuppressive environment of the tumour. Although specific antigens have been identified in several cancers; brain tumours, such as GBM, are considered poorly immunogenic. However, as detailed in this review, strategies aimed at circumventing these challenges are showing promise for GBM treatment; including identification of glioma specific antigens and endogenous immune cell activation in an attempt to overcome the immunosuppressive environment which is associated with GBM tumours. An up-to-date summary of current Phase I/II and ongoing Phase III GBM immunotherapy clinical trials is provided in addition to insights into promising preclinical approaches which are focused predominantly on increased induction of Type 1 helper T cell (T_h1) immune responses within patients.

Targeting breast cancer stem cells by dendritic cell vaccination in humanized mice with breast tumor: preliminary results

Background

Breast cancer (BC) is one of the leading cancers in women. Recent progress has enabled BC to be cured with high efficiency. However, late detection or metastatic disease often renders the disease untreatable. Additionally, relapse is the main cause of death in BC patients. Breast cancer stem cells (BCSCs) are considered to cause the development of BC and are thought to be responsible for metastasis and relapse. This study aimed to target BCSCs using dendritic cells (DCs) to treat tumor-bearing humanized mice models.

Materials and methods

NOD/SCID mice were used to produce the humanized mice by transplantation of human hematopoietic stem cells. Human BCSCs were injected into the mammary fat pad to produce BC humanized mice. Both hematopoietic stem cells and DCs were isolated from the human umbilical cord blood, and immature DCs were produced from cultured mononuclear cells. DCs were matured by BCSC-derived antigen incubation for 48 hours. Mature DCs were vaccinated to BC humanized mice with a dose of 10⁶ cells/mice, and the survival percentage was monitored in both treated and untreated groups.

Results

The results showed that DC vaccination could target BCSCs and reduce the tumor size and prolong survival.

Conclusion

These results suggested that targeting BCSCs with DCs is a promising therapy for BC.

Elevated levels of polymorphonuclear myeloid-derived suppressor cells in patients with glioblastoma highly express S100A8/9 and arginase and suppress T cell function

BACKGROUND

Gliomas are primary brain tumors that are associated with a poor prognosis. The introduction of new treatment modalities (including immunotherapy) for these neoplasms in the last 3 decades has resulted in only limited improvement in survival. Gliomas are known to create an immunosuppressive microenvironment that hampers the efficacy of (immuno)therapy. One component of this immunosuppressive environment is the myeloid-derived suppressor cell (MDSC).

METHODS

We set out to analyze the presence and activation state of MDSCs in blood (n = 41) and tumor (n = 20) of glioma patients by measuring S100A8/9 and arginase using flow cytometry and qPCR. Inhibition of T cell proliferation and cytokine production after stimulation with anti-CD3/anti-CD28 coated beads was used to measure in vitro MDSC suppression capacity.

RESULTS

We report a trend toward a tumor grade-dependent increase of both monocytic (M-) and polymorphonuclear (PMN-) MDSC subpopulations in the blood of patients with glioma. M-MDSCs of glioma patients have increased levels of intracellular S100A8/9 compared with M-MDSCs in healthy controls (HCs). Glioma patients also have increased S100A8/9 serum levels, which correlates with increased arginase activity in serum. PMN-MDSCs in both blood and tumor tissue demonstrated high expression of arginase. Furthermore, we assessed blood-derived PMN-MDSC function and showed that these cells have potent T cell suppressive function in vitro.

CONCLUSIONS

These data indicate a tumor grade-dependent increase of MDSCs in the blood of patients with a glioma. These MDSCs exhibit an increased activation state compared with MDSCs in HCs, independent of tumor grade.

Expression of CDC5L is associated with tumor progression in gliomas

Cell division cycle 5-like (CDC5L) protein is a cell cycle regulator of the G2/M transition and has been reported to participate in the catalytic step of pre-messenger RNA (mRNA) splicing and DNA damage repair. Recently, it was also found to act as a candidate oncogene in osteosarcoma and cervical tumors. However, the role of CDC5L expression in tumor biology was still unclear. Here, we analyzed the expression and clinical significance of CDC5L in gliomas. The expression of CDC5L in fresh glioma tissues and paraffin-embedded slices was evaluated by western blot and immunohistochemistry, respectively. We found that CDC5L was highly expressed in glioma tissues. The expression of CDC5L was significantly associated with glioma pathology grade and Ki-67 expression. Univariate and multivariate analyses showed that high CDC5L expression was an independent prognostic factor for glioma patients' survival. To determine whether CDC5L could regulate the proliferation of glioma cells, we transfected glioma cells with interfering RNA target CDC5L, then investigated cell proliferation with cell counting kit (CCK)-8, flow cytometry assays and colony formation analyses. Our results indicated that knockdown of CDC5L would inhibit proliferation of glioma cells. Besides, reduced expression of CDC5L could induce the apoptosis of glioma cells. These findings suggested that CDC5L might play an important role in glioma and thus be a promising therapeutic target of glioma.

In situ dendritic cell vaccination for the treatment of glioma and literature review

Glioma is one of the greatest threats to human health, and invasive growth of glioma is its major cause of death. Inhibiting or blocking angiogenesis can effectively inhibit tumor growth and metastasis or dramatically reduce the size of the original lesion. Therefore, anti-angiogenic therapy has currently become the most promising treatment strategy for glioma. Although dendritic cells (DCs) used in DC-based immunotherapy are loaded with tumor-associated antigens, the anti-tumor immune response is effectively stimulated in cytotoxic specific T lymphocytes (CTLs), thereby achieving targeted killing of tumor cells without harming surrounding normal cells. This makes it a highly promising new form of therapy. This article reviews the existing evidence regarding in situ DC vaccination for the treatment of glioma and puts forward hypotheses regarding patient, tumor, and technical factors and warrant further investigation.

Glioblastoma multiforme: emerging treatments and stratification markers beyond new drugs

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults. The standard therapy for GBM is maximal surgical resection followed by radiotherapy with concurrent and adjuvant temozolomide (TMZ). In spite of the extensive treatment, the disease is associated with poor clinical outcome. Further intensification of the standard treatment is limited by the infiltrating growth of the GBM in normal brain areas, the expected neurological toxicities with radiation doses >60 Gy and the dose-limiting toxicities induced by systemic therapy. To improve the outcome of patients with GBM, alternative treatment modalities which add low or no additional toxicities to the standard treatment are needed. Many Phase II trials on new chemotherapeutics or targeted drugs have indicated potential efficacy but failed to improve the overall or progression-free survival in Phase III clinical trials. In this review, we will discuss contemporary issues related to recent technical developments and new metabolic strategies for patients with GBM including MR (spectroscopy) imaging, (amino acid) positron emission tomography (PET), amino acid PET, surgery, radiogenomics, particle therapy, radioimmunotherapy and diets.