Vaccination of recurrent glioma patients with tumour lysate-pulsed dendritic cells elicits immune responses: results of a clinical phase I/II trial

Harnessing Immune Rejuvenation: Advances in Overcoming T Cell Senescence and Exhaustion in Cancer Immunotherapy

Immunotherapy has transformed the landscape of cancer treatment, with T cell-based strategies at the forefront of this revolution. However, the durability of these responses is frequently undermined by two intertwined phenomena: T cell exhaustion and senescence. While exhaustion is driven by chronic antigen exposure in the immunosuppressive tumor microenvironment, leading to a reversible state of diminished functionality, senescence reflects a more permanent, age- or stress-induced arrest in cellular proliferation and effector capacity. Together, these processes represent formidable barriers to sustained anti-tumor immunity. In this review, we dissect the molecular underpinnings of T cell exhaustion and senescence, revealing how these dysfunctions synergistically contribute to immune evasion and resistance across a range of solid tumors. We explore cutting-edge therapeutic approaches aimed at rewiring the exhausted and senescent T cell phenotypes. These include advances in immune checkpoint blockade, the engineering of "armored" CAR-T cells, senolytic therapies that selectively eliminate senescent cells, and novel interventions that reinvigorate the immune system's capacity for tumor eradication. By spotlighting emerging strategies that target both exhaustion and senescence, we provide a forward-looking perspective on the potential to harness immune rejuvenation. This comprehensive review outlines the next frontier in cancer immunotherapy: unlocking durable responses by overcoming the immune system's intrinsic aging and exhaustion, ultimately paving the way for transformative therapeutic breakthroughs.

Clinical immunotherapy in glioma: current concepts, challenges, and future perspectives

Glioma is one of the common tumors in the central nervous system, and its treatment methods (surgery, radiotherapy, and chemotherapy) lack specificity and have a poor prognosis. With the development of immunology, cell biology, and genomics, tumor immunotherapy has ushered in a new era of tumor therapy, achieving significant results in other invasive cancers such as advanced melanoma and advanced non-small cell lung cancer. Currently, the clinical trials of immunotherapy in glioma are also progressing rapidly. Here, this review summarizes promising immunotherapy methods in recent years, reviews the current status of clinical trials, and discusses the challenges and prospects of glioma immunotherapy.

A systematic review of immunotherapy in high-grade glioma: learning from the past to shape future perspectives

High-grade gliomas (HGGs) constitute the most common malignant primary brain tumor with a poor prognosis despite the standard multimodal therapy. In recent years, immunotherapy has changed the prognosis of many cancers, increasing the hope for HGG therapy. We conducted a comprehensive search on PubMed, Scopus, Embase, and Web of Science databases to include relevant studies. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Fifty-two papers were finally included (44 phase II and eight phase III clinical trials) and further divided into four different subgroups: 14 peptide vaccine trials, 15 dendritic cell vaccination (DCV) trials, six immune checkpoint inhibitor (ICI) trials, and 17 miscellaneous group trials that included both "active" and "passive" immunotherapies. In the last decade, immunotherapy created great hope to increase the survival of patients affected by HGGs; however, it has yielded mostly dismal results in the setting of phase III clinical trials. An in-depth analysis of these clinical results provides clues about common patterns that have led to failures at the clinical level and helps shape the perspective for the next generation of immunotherapies in neuro-oncology.

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.

Dendritic cell vaccine of gliomas: challenges from bench to bed

Gliomas account for the majority of brain malignant tumors. As the most malignant subtype of glioma, glioblastoma (GBM) is barely effectively treated by traditional therapies (surgery combined with radiochemotherapy), resulting in poor prognosis. Meanwhile, due to its "cold tumor" phenotype, GBM fails to respond to multiple immunotherapies. As its capacity to prime T cell response, dendritic cells (DCs) are essential to anti-tumor immunity. In recent years, as a therapeutic method, dendritic cell vaccine (DCV) has been immensely developed. However, there have long been obstacles that limit the use of DCV yet to be tackled. As is shown in the following review, the role of DCs in anti-tumor immunity and the inhibitory effects of tumor microenvironment (TME) on DCs are described, the previous clinical trials of DCV in the treatment of GBM are summarized, and the challenges and possible development directions of DCV are analyzed.

Knowledge structure and hotspots research of glioma immunotherapy: a bibliometric analysis

Background

Glioma is the most common primary brain tumor. Traditional treatments for glioma include surgical resection, radiotherapy, chemotherapy, and bevacizumab therapy, but their efficacies are limited. Immunotherapy provides a new direction for glioma treatment. This study aimed to summarize the knowledge structure and research hotspots of glioma immunotherapy through a bibliometric analysis.

Method

Publications pertaining to glioma immunotherapy published during the period from 1st January 1990 to 27th March 2023 were downloaded from the Web of Science Core Collection (WoSCC). Bibliometric analysis and visualization were performed using the CiteSpace, VOSviewer, Online Analysis Platform of Literature Metrology, and R software. The hotspots and prospects of glioma immunotherapy research were illustrated via analyzing the countries, institutions, journals, authors, citations and keywords of eligible publications.

Results

A total of 1,929 publications pertaining to glioma immunotherapy in 502 journals were identified as of 27th March 2023, involving 9,505 authors from 1,988 institutions in 62 countries. Among them were 1,285 articles and 644 reviews. Most of publications were produced by the United States. JOURNAL OF NEURO-ONCOLOGY published the majority of publications pertaining to glioma immunotherapy. Among the authors, Lim M contributed the largest number of publications. Through analyzing keyword bursts and co-cited references, immune-checkpoint inhibitors (ICIs) were identified as the research focus and hotspot.

Conclusion

Using a bibliometric analysis, this study provided the knowledge structure and research hotspots in glioma immunotherapy research during the past 33 years, with ICIs staying in the current and future hotspot. Our findings may direct the research of glioma immunotherapy in the future.

Deciphering immune microenvironment and cell evasion mechanisms in human gliomas

Gliomas are considered one of the most malignant cancers in the body. Despite current therapies, including surgery, chemotherapy, and radiotherapy, these tumors usually recur with more aggressive and resistant phenotypes. Indeed, the survival following these conventional therapies is very poor, which makes immunotherapy the subject of active research at present. The anti-tumor immune response could also be considered a prognostic factor since each stage of cancer development is regulated by immune cells. However, glioma microenvironment contains malignant cells that secrete numerous chemokines, cytokines and growth factors, promoting the infiltration of immunosuppressive cells into the tumor, which limit the functioning of the immune system against glioma cells. Recently, researchers have been able to reverse the immune resistance of cancer cells and thus activate the anti-tumor immune response through different immunotherapy strategies. Here, we review the general concept of glioma's immune microenvironment and report the impact of its distinct components on the anti-tumor immune response. We also discuss the mechanisms of glioma cell evasion from the immune response and pinpoint some potential therapeutic pathways, which could alleviate such resistance.

Definition and Characterization of SOX11-Derived T Cell Epitopes towards Immunotherapy of Glioma

The transcription factor SOX11 is a tumor-associated antigen with low expression in normal cells, but overexpression in glioblastoma (GBM). So far, conventional surgery, chemotherapy, and radiotherapy have not substantially improved the dismal prognosis of relapsed/refractory GBM patients. Immunotherapy is considered a promising strategy against GBM, but there is a fervent need for better immunotargets in GBM. To this end, we performed an in silico prediction study on SOX11, which primarily yielded ten promising HLA-A*0201-restricted peptides derived from SOX11. We defined a novel peptide FMACSPVAL, which had the highest score according to in silico prediction (6.02 nM by NetMHC-4.0) and showed an exquisite binding affinity to the HLA-A*0201 molecule in the peptide-binding assays. In the IFN-γ ELISPOT assays, FMACSPVAL demonstrated a high efficiency for generating SOX11-specific CD8⁺ T cells. Nine out of thirty-two healthy donors showed a positive response to SOX11, as assessed by the ELISPOT assays. Therefore, this novel antigen peptide epitope seems to be promising as a target for T cell-based immunotherapy in GBM. The adoptive transfer of in vitro elicited SOX11-specific CD8⁺ T cells constitutes a potential approach for the treatment of GBM patients.

Immunotherapy associated central nervous system complications in primary brain tumors

Advances clarifying the genetics and function of the immune system within the central nervous system (CNS) and brain tumor microenvironment have led to increasing momentum and number of clinical trials using immunotherapy for primary brain tumors. While neurological complications of immunotherapy in extra-cranial malignancies is well described, the CNS toxicities of immunotherapy in patients with primary brain tumors with their own unique physiology and challenges are burgeoning. This review highlights the emerging and unique CNS complications associated with immunotherapy including checkpoint inhibitors, oncolytic viruses, adoptive cell transfer/chimeric antigen receptor (CAR) T cell and vaccines for primary brain tumors, as well as reviews modalities that have been currently employed or are undergoing investigation for treatment of such toxicities.

Personalised therapeutic approaches to glioblastoma: A systematic review

Introduction

Glioblastoma is the most common and malignant primary brain tumour with median survival of 14.6 months. Personalised medicine aims to improve survival by targeting individualised patient characteristics. However, a major limitation has been application of targeted therapies in a non-personalised manner without biomarker enrichment. This has risked therapies being discounted without fair and rigorous evaluation. The objective was therefore to synthesise the current evidence on survival efficacy of personalised therapies in glioblastoma.

Methods

Studies reporting a survival outcome in human adults with supratentorial glioblastoma were eligible. PRISMA guidelines were followed. MEDLINE, Embase, Scopus, Web of Science and the Cochrane Library were searched to 5th May 2022. Clinicaltrials.gov was searched to 25th May 2022. Reference lists were hand-searched. Duplicate title/abstract screening, data extraction and risk of bias assessments were conducted. A quantitative synthesis is presented.

Results

A total of 102 trials were included: 16 were randomised and 41 studied newly diagnosed patients. Of 5,527 included patients, 59.4% were male and mean age was 53.7 years. More than 20 types of personalised therapy were included: targeted molecular therapies were the most studied (33.3%, 34/102), followed by autologous dendritic cell vaccines (32.4%, 33/102) and autologous tumour vaccines (10.8%, 11/102). There was no consistent evidence for survival efficacy of any personalised therapy.

Conclusion

Personalised glioblastoma therapies remain of unproven survival benefit. Evidence is inconsistent with high risk of bias. Nonetheless, encouraging results in some trials provide reason for optimism. Future focus should address target-enriched trials, combination therapies, longitudinal biomarker monitoring and standardised reporting.

Immunotherapy for the treatment of pediatric brain tumors: a narrative review

BACKGROUND AND OBJECTIVE

The goal of this narrative review is to report and summarize the completed pediatric immunotherapy clinical trials for primary CNS tumors. Pediatric central nervous system (CNS) tumors are the most common cause of pediatric solid cancer in children aged 0 to 14 years and the leading cause of cancer mortality. Survival rates for some pediatric brain tumors have improved, however, there remains a large portion of pediatric brain tumors with poor survival outcomes despite advances in treatment. Cancer immunotherapy is a growing field that has shown promise in the treatment of pediatric brain tumors that have historically shown a poor response to treatment. This narrative review provides a summary and discussion of the published literature focused on treating pediatric brain tumors with immunotherapy.

METHODS

MEDLINE via PubMed, Embase and Scopus via Elsevier were searched. The search utilized a combination of keywords and subject headings to include pediatrics, brain tumors, and immunotherapies. Manuscripts included in the analysis included completed clinical studies using any immunotherapy intervention with a patient population that consisted of at least half pediatric patients (<18 years) with primary CNS tumors. Conference abstracts were excluded as well as studies that did not include completed safety or primary outcome results.

KEY CONTENT AND FINDINGS

Search results returned 1,494 articles. Screening titles and abstracts resulted in 180 articles for full text review. Of the 180 articles, 18 were included for analysis. Another two articles were ultimately included after review of references and inclusion of newly published articles, for a total of 20 included articles. Immunotherapies included dendritic cell vaccines, oncolytic virotherapy/viral immunotherapy, chimeric antigen receptor (CAR) T-cell therapy, peptide vaccines, immunomodulatory agents, and others.

CONCLUSIONS

In this review, 20 published articles were highlighted which use immunotherapy in the treatment of primary pediatric brain tumors. To date, most of the studies published utilizing immunotherapy were phase I and pilot studies focused primarily on establishing safety and maximum dose-tolerance and toxicity while monitoring survival endpoints. With established efficacy and toxicity profiles, future trials may progress to further understanding the overall survival and quality of life benefits to pediatric patients with primary brain tumors.

Dendritic cell vaccines for glioblastoma fail to complete clinical translation: Bottlenecks and potential countermeasures

Glioblastoma (GBM) is a heterogeneous and invasive WHO grade IV brain tumor. Patients with GBM have a median overall survival (OS) of only 14 to 17 months when treated with surgical resection and chemoradiation. As one of the most promising anti-tumor immunotherapies, dendritic cell (DC) vaccines have demonstrated good efficacy, safety, and tolerability in many clinical trials. However, to date, no Phase III clinical trial has achieved positive endpoints and truly implement clinical development and transformation. Moreover, the survival benefits of DC vaccines for patients with GBM seem to have a delayed effect; therefore, we urgently require strategies to optimize DC vaccines to advance the time point of its survival benefits. Here, we discuss the latest clinical trial progress of DC vaccines in GBM and summarize the benefits and drawbacks of various vaccine design options, as well as the challenges faced in clinical translation. Moreover, we target future combination therapy strategies for DC vaccines in GBM, which provides a new perspective for comprehensively understanding the effectiveness, limitations, and new directions of the development of DC vaccines.

Delayed Effect of Dendritic Cells Vaccination on Survival in Glioblastoma: A Systematic Review and Meta-Analysis

Background: Dendritic cell vaccination (DCV) strategies, thanks to a complex immune response, may flare tumor regression and improve patients’ long-term survival. This meta-analysis aims to assess the efficacy of DCV for newly diagnosed glioblastoma patients in clinical trials. Methods: The study databases, including PubMed, Web of Knowledge, Google Scholar, Scopus, and Cochrane, were searched by two blinded investigators considering eligible studies based on the following keywords: “glioblastoma multiforme”, “dendritic cell”, “vaccination”, “immunotherapy”, “immune system”, “immune response”, “chemotherapy”, “recurrence”, and “temozolomide”. Among the 157 screened, only 15 articles were eligible for the final analysis. Results: Regimens including DCV showed no effect on 6-month progression-free survival (PFS, HR = 1.385, 95% CI: 0.822–2.335, p = 0.673) or on 6-month overall survival (OS, HR = 1.408, 95% CI: 0.882–2.248, p = 0.754). In contrast, DCV led to significantly longer 1-year OS (HR = 1.936, 95% CI: 1.396–2.85, p = 0.001) and longer 2-year OS (HR = 3.670, 95% CI: 2.291–5.879, p = 0.001) versus control groups. Hence, introducing DCV could lead to increased 1 and 2-year survival of patients by 1.9 and 3.6 times, respectively. Conclusion: Antitumor regimens including DCV can effectively improve mid-term survival in patients suffering glioblastoma multiforme (GBM), but its impact emerges only after one year from vaccination. These data indicate the need for more time to achieve an anti-GBM immune response and suggest additional therapeutics, such as checkpoint inhibitors, to empower an earlier DCV action in patients affected by a very poor prognosis.

Immunotherapy for Neuro-oncology

Immunotherapy has changed the landscape of treatment of many solid and hematological malignancies and is at the forefront of cancer breakthroughs. Several circumstances unique to the central nervous system (CNS) such as limited space for an inflammatory response, difficulties with repeated sampling, corticosteroid use for management of cerebral edema, and immunosuppressive mechanisms within the tumor and brain parenchyma have posed challenges in clinical development of immunotherapy for intracranial tumors. Nonetheless, the success of immunotherapy in brain metastases (BMs) from solid cancers such as melanoma and non-small cell lung cancer (NSCLC) proves that the CNS is not an immune-privileged organ and is capable of initiating and regulating immune responses that lead to tumor control. However, the development of immunotherapeutics for the most malignant primary brain tumor, glioblastoma (GBM), has been challenging due to systemic and profound tumor-mediated immunosuppression unique to GBM, intratumoral and intertumoral heterogeneity, and lack of stably expressed clonal antigens. Here, we review recent advances in the field of immunotherapy for neuro-oncology with a focus on BM, GBM, and rare CNS cancers.

Immunogenic cell death and its therapeutic or prognostic potential in high-grade glioma

Immunogenic cell death (ICD) has emerged as a key component of therapy-induced anti-tumor immunity. Over the past few years, ICD was found to play a pivotal role in a wide variety of novel and existing treatment modalities. The clinical application of these techniques in cancer treatment is still in its infancy. Glioblastoma (GBM) is the most lethal primary brain tumor with a dismal prognosis despite maximal therapy. The development of new therapies in this aggressive type of tumors remains highly challenging partially due to the cold tumor immune environment. GBM could therefore benefit from ICD-based therapies stimulating the anti-tumor immune response. In what follows, we will describe the mechanisms behind ICD and the ICD-based (pre)clinical advances in anticancer therapies focusing on GBM.

Generation of Tumor Targeted Dendritic Cell Vaccines with Improved Immunogenic and Migratory Phenotype

Our group has employed methodologies for effective ex vivo generation of dendritic cell (DC) vaccines for patients with primary malignant brain tumors. In order to reliably produce the most potent, most representational vaccinated DC that will engender an antitumor response requires the ability to orchestrate multiple methodologies that address antigen cross-presentation, T-cell costimulation and polarization, and migratory capacity. In this chapter, we describe a novel method for augmenting the immunogenicity and migratory potential of DCs for their use as vaccines. We have elucidated methodologies to avoid the phenomenon known as immunodominance in generating cancer vaccines. We have found that culturing DC progenitors in serum-free conditions for the duration of the differentiation protocol results in a more homogeneously mature population of DCs that exhibit enhanced immunogenicity compared to DCs generated in serum-containing culture conditions. Furthermore, we demonstrate our method for generating high mobility DCs that readily migrate toward lymphoid organ chemoattractants using CCL3 protein. The combination of these two approaches represents a facile and clinically tractable methodology for generating highly mature DCs with excellent migratory capacity.

Dendritic Cell Vaccination of Glioblastoma: Road to Success or Dead End

Glioblastomas (GBM) are the most frequent and aggressive malignant primary brain tumor and remains a therapeutic challenge: even after multimodal therapy, median survival of patients is only 15 months. Dendritic cell vaccination (DCV) is an active immunotherapy that aims at inducing an antitumoral immune response. Numerous DCV trials have been performed, vaccinating hundreds of GBM patients and confirming feasibility and safety. Many of these studies reported induction of an antitumoral immune response and indicated improved survival after DCV. However, two controlled randomized trials failed to detect a survival benefit. This raises the question of whether the promising concept of DCV may not hold true or whether we are not yet realizing the full potential of this therapeutic approach. Here, we discuss the results of recent vaccination trials, relevant parameters of the vaccines themselves and of their application, and possible synergies between DCV and other therapeutic approaches targeting the immunosuppressive microenvironment of GBM.

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.

Clinical implication of cellular vaccine in glioma: current advances and future prospects

Gliomas, especially glioblastomas, represent one of the most aggressive and difficult-to-treat human brain tumors. In the last few decades, clinical immunotherapy has been developed and has provided exceptional achievements in checkpoint inhibitors and vaccines for cancer treatment. Immunization with cellular vaccines has the advantage of containing specific antigens and acceptable safety to potentially improve cancer therapy. Based on T cells, dendritic cells (DC), tumor cells and natural killer cells, the safety and feasibility of cellular vaccines have been validated in clinical trials for glioma treatment. For TAA engineered T cells, therapy mainly uses chimeric antigen receptors (IL13Rα2, EGFRvIII and HER2) and DNA methylation-induced technology (CT antigen) to activate the immune response. Autologous dendritic cells/tumor antigen vaccine (ADCTA) pulsed with tumor lysate and peptides elicit antigen-specific and cytotoxic T cell responses in patients with malignant gliomas, while its pro-survival effect is biased. Vaccinations using autologous tumor cells modified with TAAs or fusion with fibroblast cells are characterized by both effective humoral and cell-mediated immunity. Even though few therapeutic effects have been observed, most of this therapy showed safety and feasibility, asking for larger cohort studies and better guidelines to optimize cellular vaccine efficiency in anti-glioma therapy.

Antitumour dendritic cell vaccination in a priming and boosting approach

Mobilizing antitumour immunity through vaccination potentially constitutes a powerful anticancer strategy but has not yet provided robust clinical benefits in large patient populations. Although major hurdles still exist, we believe that currently available strategies for vaccines that target dendritic cells or use them to present antitumour antigens could be integrated into existing clinical practice using prime-boost approaches. In the priming phase, these approaches capitalize on either standard treatment modalities to trigger in situ vaccination and release tumour antigens or vaccination with dendritic cells loaded with tumour lysates or patient-specific neoantigens. In a second boost phase, personalized synthetic vaccines specifically boost T cells that were triggered during the priming phase. This immunotherapy approach has been enabled by the substantial recent improvements in dendritic cell vaccines. In this Perspective, we discuss these improvements, highlight how the prime-boost approach can be translated into clinical practice and provide solutions for various anticipated hurdles.

Suppression of TGF-β and IL-10 receptors on self-differentiated dendritic cells by short-hairpin RNAs enhanced activation of effector T-cells against cholangiocarcinoma cells

Cholangiocarcinoma (CCA) is an aggressive tumor that is associated with high rates of recurrence and mortality. This is due, in part, to the fact that CCA cells and their microenvironment secrete immunosuppressive cytokines, transforming growth factor-β (TGF-β) and interleukin-10 (IL-10), that inhibit dendritic cell (DC) functions, which, in turn, results in the decreased anti-tumor activity of T-cells. We hypothesized that the TGF-β receptor and IL-10 blockade on dendritic cells would improve DC function, thereby allowing improved activation of T cells against CCA cells. To test our hypothesis, we generated self-differentiated DCs (SD-DCs) via transduction of human peripheral blood monocytes with lentivirus expressing IL-4 and GM-CSF. SD-DCs were transduced with a second lentivirus containing short-hairpin RNAs (shRNAs) to knock-down TGF-βRII and IL-10RA mRNAs. Immunoblot confirmed the reduced expression levels of TGF-β and IL-10 receptors in both SD-DCs that were transduced with a single and/or combination of lentiviruses containing shRNAs. SD-DCs were thereafter pulsed with tumor antigens extracted from CCA cell lines in an effort to activate DC function. MHC class II (HLA-DR) and co-stimulatory molecules (CD40 and CD86) on SD-DCs were upregulated to levels comparable to those on DCs generated by the conventional method. Suppression of TGF-β and IL-10 receptors on SD-DCs influenced the effector T-cells to produce IFN-γ, which enhanced their ability to kill CCA cells. The preparation of adoptive effector T-cells holds the potential of becoming a novel therapy for cellular immunotherapy in CCA.

Immunotherapy for Neuro-Oncology

Immunotherapy has changed the landscape of treatment of many solid and hematological malignancies and is at the forefront of cancer breakthroughs. Several circumstances unique to the central nervous system (CNS) such as limited space for an inflammatory response, difficulties with repeated sampling, corticosteroid use for management of cerebral edema, and immunosuppressive mechanisms within the tumor and brain parenchyma have posed challenges in clinical development of immunotherapy for intracranial tumors. Nonetheless, the success of immunotherapy in brain metastases (BMs) from solid cancers such as melanoma and non-small cell lung cancer (NSCLC) proves that the CNS is not an immune-privileged organ and is capable of initiating and regulating immune responses that lead to tumor control. However, the development of immunotherapeutics for the most malignant primary brain tumor, glioblastoma (GBM), has been challenging due to systemic and profound tumor-mediated immunosuppression unique to GBM, intratumoral and intertumoral heterogeneity, low mutation burden, and lack of stably expressed clonal antigens. Here, we review recent advances in the field of immunotherapy for neuro-oncology with a focus on BM and GBM.

Biological intratumoral therapy for the high-grade glioma part II: vector- and cell-based therapies and radioimmunotherapy

Management of high-grade gliomas (HGGs) remains a complex challenge with an overall poor prognosis despite aggressive multimodal treatment. New translational research has focused on maximizing tumor cell eradication through improved tumor cell targeting while minimizing collateral systemic side effects. In particular, biological intratumoral therapies have been the focus of novel translational research efforts due to their inherent potential to be both dynamically adaptive and target specific. This two part review will provide an overview of biological intratumoral therapies that have been evaluated in human clinical trials in HGGs, and summarize key advances and remaining challenges in the development of these therapies as a potential new paradigm in the management of HGGs. Part II discusses vector-based therapies, cell-based therapies and radioimmunotherapy.

A Characterization of Dendritic Cells and Their Role in Immunotherapy in Glioblastoma: From Preclinical Studies to Clinical Trials

Glioblastoma (GBM) is the most common and fatal primary central nervous system malignancy in adults with a median survival of less than 15 months. Surgery, radiation, and chemotherapy are the standard of care and provide modest benefits in survival, but tumor recurrence is inevitable. The poor prognosis of GBM has made the development of novel therapies targeting GBM of paramount importance. Immunotherapy via dendritic cells (DCs) has garnered attention and research as a potential strategy to boost anti-tumor immunity in recent years. As the “professional” antigen processing and presenting cells, DCs play a key role in the initiation of anti-tumor immune responses. Pre-clinical studies in GBM have shown long-term tumor survival and immunological memory in murine models with stimulation of DC activity with various antigens and costimulatory molecules. Phase I and II clinical trials of DC vaccines in GBM have demonstrated some efficacy in improving the median overall survival with minimal to no toxicity with promising initial results from the first Phase III trial. However, there remains no standardization of vaccines in terms of which antigens are used to pulse DCs ex vivo, sites of DC injection, and optimal adjuvant therapies. Future work with DC vaccines aims to elucidate the efficacy of DC-based therapy alone or in combination with other immunotherapy adjuvants in additional Phase III trials.

High-grade glioma associated immunosuppression does not prevent immune responses induced by therapeutic vaccines in combination with Treg depletion

High-grade gliomas (HGG) exert systemic immunosuppression, which is of particular importance as immunotherapeutic strategies such as therapeutic vaccines are increasingly used to treat HGGs. In a first cohort of 61 HGG patients we evaluated a panel of 30 hematological and 34 plasma biomarkers. Then, we investigated in a second cohort of 11 relapsed HGG patients receiving immunomodulation with metronomic cyclophosphamide upfront to a DC-based vaccine whether immune abnormalities persisted and whether they hampered induction of IFNγ⁺ T-cell responses. HGG patients from the first cohort showed increased numbers of leukocytes, neutrophils and MDSCs and in parallel reduced numbers of CD4⁺/CD8⁺ T-cells, plasmacytoid and conventional DC2s. MDSCs and T-cell alterations were more profound in WHO IV° glioma patients. Moreover, levels of MDSCs and epidermal growth factor were negatively associated with survival. Serum levels of IL-2, IL-4, IL-5 and IL-10 were altered in HGG patients, however, without any impact on clinical outcome. In the immunotherapy cohort, 6-month overall survival was 100%. Metronomic cyclophosphamide led to > 40% reduction of regulatory T cells (T_reg). In parallel to T_reg-depletion, MDSCs and DC subsets became indistinguishable from healthy controls, whereas T-lymphopenia persisted. Despite low T-cells, IFNγ-responses could be induced in 9/10 analyzed cases. Importantly, frequency of CD8⁺VLA-4⁺ T-cells with CNS-homing properties, but not of CD4⁺ VLA-4⁺ T-cells, increased during vaccination. Our study identifies several features of systemic immunosuppression in HGGs. Metronomic cyclophosphamide in combination with an active immunization alleviates the latter and the combined treatment allows induction of a high rate of anti-glioma immune responses.

Dendritic cell vaccines for high-grade gliomas

Glioblastoma (GBM) is the most common and fatal primary adult brain tumor. To date, various promising chemotherapeutic regimens have been trialed for use in GBM; however, temozolomide (TMZ) therapy remains the only US Food and Drug Administration-approved first-line chemotherapeutic option for newly diagnosed GBM. Despite maximal therapy with surgery and combined concurrent chemoradiation and adjuvant TMZ therapy, the median overall survival remains approximately 14 months. Given the failure of conventional chemotherapeutic strategies in GBM, there has been renewed interest in the role of immunotherapy in GBM. Dendritic cells are immune antigen-presenting cells that play a role in both the innate and adaptive immune system, thereby making them prime vehicles for immunotherapy via dendritic cell vaccinations (DCVs) in various cancers. There is great enthusiasm surrounding the use of DCVs for GBM with multiple ongoing trials. In this review, we comprehensively summarize the safety, efficacy, and quality of life results from 33 trials reporting on DCV for 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.

A randomized controlled phase II trial of vaccination with lysate-loaded, mature dendritic cells integrated into standard radiochemotherapy of newly diagnosed glioblastoma (GlioVax): study protocol for a randomized controlled trial

Background

Despite the combination of surgical resection, radio- and chemotherapy, median survival of glioblastoma multiforme (GBM) patients only slightly increased in the last years. Disease recurrence is definite with no effective therapy existing after tumor removal. Dendritic cell (DC) vaccination is a promising active immunotherapeutic approach. There is clear evidence that it is feasible, results in immunological anti-tumoral responses, and appears to be beneficial for survival and quality of life of GBM patients. Moreover, combining it with the standard therapy of GBM may allow exploiting synergies between the treatment modalities. In this randomized controlled trial, we seek to confirm these promising initial results.

Methods

One hundred and thirty-six newly diagnosed, isocitrate dehydrogenase wildtype GBM patients will be randomly allocated (1:1 ratio, stratified by O6-methylguanine-DNA-methyltransferase promotor methylation status) after near-complete resection in a multicenter, prospective phase II trial into two groups: (1) patients receiving the current therapeutic “gold standard” of radio/temozolomide chemotherapy and (2) patients receiving DC vaccination as an add-on to the standard therapy. A recruitment period of 30 months is anticipated; follow-up will be 2 years. The primary objective of the study is to compare overall survival (OS) between the two groups. Secondary objectives are comparing progression-free survival (PFS) and 6-, 12- and 24-month OS and PFS rates, the safety profile, overall and neurological performance and quality of life.

Discussion

Until now, close to 500 GBM patients have been treated with DC vaccination in clinical trials or on a compassionate-use basis. Results have been encouraging, but cannot provide robust evidence of clinical efficacy because studies have been non-controlled or patient numbers have been low. Therefore, a prospective, randomized phase II trial with a sufficiently large number of patients is now mandatory for clear evidence regarding the impact of DC vaccination on PFS and OS in GBM.

Trial registration

Protocol code: GlioVax, date of registration: 17. February 2017.

Trial identifier: EudraCT-Number 2017–000304-14.

German Registry for Clinical Studies, ID: DRKS00013248 (approved primary register in the WHO network) and at ClinicalTrials.gov, ID: NCT03395587. Registered on 11 March 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2659-7) contains supplementary material, which is available to authorized users.

Clinical Trials Investigating Immune Checkpoint Blockade in Glioblastoma

OPINION STATEMENT

Immune checkpoint inhibitors have changed the landscape of cancer immunotherapy and are being integrated into the standard of care for a variety of solid and hematologic malignancies. Glioblastoma (GBM) is the most common primary malignant brain tumor in adults and carries a grave prognosis despite advances in surgical resection, chemotherapy, and radiation therapy. Implementing immunotherapy for brain tumors mandates additional considerations due to the unique structural and immunologic milieu of the central nervous system (CNS). Nevertheless, strong data from preclinical studies have driven clinical trials of immune checkpoint blockade for newly diagnosed and recurrent GBM. The focus of this review is to discuss the ongoing clinical trials of checkpoint inhibitors in GBM and review the immunologic rationale for ongoing and future trial designs.

Branched multipeptide immunotherapy for glioblastoma using human leukocyte antigen-A*0201-restricted cytotoxic T-lymphocyte epitopes from ERBB2, BIRC5 and CD99

We investigated the use of cytotoxic T-lymphocyte (CTL) epitopes in peptide immunotherapy for glioblastoma. Three peptides (ERBB2, BIRC5 and CD99) were selected based on their peptide-T2 cell binding affinities and combined in a multipeptide cocktail or a branched multipeptide synthesized with mini-polyethylene glycol spacers. Dendritic cells (DCs) pulsed with the multipeptide cocktail or branched multipeptide were compared based on their immunophenotype and cytokine secretion. FACS analysis of alpha-type 1 polarized dendritic cells (αDC1s) revealed that both groups highly expressed CD80, CD83 and CD86, indicating that both treatments efficiently generated mature αDC1s with the expected phenotype. Production of IL-12p70, IL-12p40 and IL-10 also increased upon αDC1 maturation in both groups. CTLs stimulated by either αDC1 group (“DC-CTLs”) included numerous IFN-γ-secreting cells against T2 cells loaded with the corresponding multipeptides. Large numbers of IFN-γ-secreting cells were observed when human glioblastoma cell lines and primary cells were treated with multipeptide-pulsed DC-CTLs. Both multipeptide-pulsed DC-CTL groups exhibited cytotoxic activity of 40-60% against the U251 cell line and 60-80% against primary cells. Branched multipeptide from ERBB2, BIRC5 and CD99 stably bound with T2 cells, and its cytotoxicity toward target cells was similar to that of the multipeptide cocktail. Thus, branched multipeptides could be promising candidates for immunotherapeutic glioblastoma treatment.

Cellular immunotherapy of cancer: an overview and future directions

The clinical success of checkpoint inhibitors has led to a renaissance of interest in cancer immunotherapies. In particular, the possibility of ex vivo expanding autologous lymphocytes that specifically recognize tumor cells has attracted much research and clinical trial interest. In this review, we discuss the historical background of tumor immunotherapy using cell-based approaches, and provide some rationale for overcoming current barriers to success of autologous immunotherapy. An overview of adoptive transfer of lymphocytes, tumor infiltrating lymphocytes and dendritic cell therapies is provided. We conclude with discussing the possibility of gene-manipulating immune cells in order to augment therapeutic activity, including silencing of the immune-suppressive zinc finger orphan nuclear receptor, NR2F6, as an attractive means of overcoming tumor-associated immune suppression.

Dendritic cell based vaccination strategy: an evolving paradigm

Malignant gliomas (MG), tumors of glial origin, are the most commonly diagnosed primary intracranial malignancies in adults. Currently available treatments have provided only modest improvements in overall survival and remain limited by inevitable local recurrence, necessitating exploration of novel therapies. Among approaches being investigated, one of the leading contenders is immunotherapy, which aims to modulate immune pathways to stimulate the selective destruction of malignant cells. Dendritic cells (DCs) are potent initiators of adaptive immune responses and therefore crucial players in the development and success of immunotherapy. Clinical trials of various DC-based vaccinations have demonstrated the induction of anti-tumor immune responses and prolonged survival in the setting of many cancers. In this review, we summarize current literature regarding DCs and their role in the tumor microenvironment, their application and current clinical use in immunotherapy, current challenges limiting their efficacy in anti-cancer therapy, and future avenues for developing successful anti-tumor DC-based vaccines.

Tumor Vaccines for Malignant Gliomas

Despite continued research efforts, glioblastoma multiforme (GBM) remains the deadliest brain tumor. Immunotherapy offers a novel way to treat this disease, the genetic signature of which is not completely elucidated. Additionally, these tumors are known to induce immunosuppression in the surrounding tumor microenvironment via an array of mechanisms, making effective treatment all the more difficult. The immunotherapeutic strategy of using tumor vaccines offers a way to harness the activity of the host immune system to potentially control tumor progression. GBM vaccines can react to a variety of tumor-specific antigens, which can be harvested from the patient's unique pathological condition using selected immunotherapy techniques. This article reviews the rationale behind and development of GBM vaccines, the relevant clinical trials, and the challenges involved in this treatment strategy.

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.

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.

The inflammatory cytokine IL-22 promotes murine gliomas via proliferation

Interleukin (IL)-22 is newly identified proinflammatory cytokine involved in the T helper (Th)17 and Th22 response. However, the possible role of IL-22 in glioma remains uncertain. The results of the present study demonstrated higher expression levels of IL-22 and the receptor IL-22BP in the brain of GL261 glioma-inoculation mice, suggesting the regulatory role of IL-22 in glioma. Injection of IL-22 increased the severity of glioma in vivo and higher expression levels of IL-6, IL-1β and tumor necrosis factor (TNF)-α were detected in the brain using ELISA following IL-22 injection. To elucidate the mechanism underlying the effects of IL-22, the present study aimed firstly to determine the expression levels of IL-22 receptor in a glioma cell line via reverse transcription quantitative polymerase chain reaction. IL-22 treatment significantly increased the expression levels of signal transducer and activator of transcription (STAT)3 and the mRNA expression levels of STAT6 compared with the vehicle control. These results suggested that IL-22 may activate the Janus kinase (JAK)/STAT signaling pathway in glioma. Furthermore, IL-22 positively regulated the proliferation of glioma, consistent with its role in vivo. Conversely, IL-22-deficient mice exhibited prolonged survival compared with wild-type (WT) mice, and the expression levels of inflammatory cytokines were decreased in the brain of IL-22 knock-out (KO) mice compared with WT mice. Concordant with these results, it was observed that IL-22-neutralising antibody was able to increase the survival of mice with glioma and attenuate the disease by significantly reducing the cytokine levels in the brain. In conclusion, the results of the present study demonstrated that expression levels of IL-22 in the brain of mice with glioma may enhance symptoms due to the increased cytokine production of IL-6, IL-1β and TNF-α; this is consistent with IL-6/JAK/STAT signalling activation in vitro. Decreasing the expression levels of IL-22, achieved either with IL-22-KO mice or IL-22-neutralising antibody demonstrated protective effects on glioma development. Therefore, IL-22 may serve as a potential therapeutic target for glioma.

Dendritic cell immunotherapy versus bevacizumab plus irinotecan in recurrent malignant glioma patients: a survival gain analysis

BACKGROUND

The bevacizumab and irinotecan protocol is considered a standard treatment regimen for recurrent malignant glioma. Recent advances in immunotherapy have hinted that vaccination with dendritic cells could become an alternative salvage therapy for the treatment of recurrent malignant glioma.

METHODS

A search was performed on PubMed, Cochrane Library, Web of Science, ScienceDirect, and Embase in order to identify studies with patients receiving bevacizumab plus irinotecan or dendritic cell therapy for recurrent malignant gliomas. The data obtained from these studies were used to perform a systematic review and survival gain analysis.

RESULTS

Fourteen clinical studies with patients receiving either bevacizumab plus irinotecan or dendritic cell vaccination were identified. Seven studies followed patients that received bevacizumab plus irinotecan (302 patients) and seven studies included patients that received dendritic cell immunotherapy (80 patients). For the patients who received bevacizumab plus irinotecan, the mean reported median overall survival was 7.5 (95% confidence interval [CI] 4.84-10.16) months. For the patients who received dendritic cell immunotherapy, the mean reported median overall survival was 17.9 (95% CI 11.34-24.46) months. For irinotecan + bevacizumab group, the mean survival gain was -0.02±2.00, while that for the dendritic cell immunotherapy group was -0.01±4.54.

CONCLUSION

For patients with recurrent malignant gliomas, dendritic cell immunotherapy treatment does not have a significantly different effect when compared with bevacizumab and irinotecan in terms of survival gain (P=0.535) and does not improve weighted survival gain (P=0.620).

Cerenkov Radiation Induced Photodynamic Therapy Using Chlorin e6-Loaded Hollow Mesoporous Silica Nanoparticles

Traditional photodynamic therapy (PDT) requires external light to activate photosensitizers for therapeutic purposes. However, the limited tissue penetration of light is still a major challenge for this method. To overcome this limitation, we report an optimized system that uses Cerenkov radiation for PDT by using radionuclides to activate a well-known photosensitizer (chlorin e6, Ce6). By taking advantage of hollow mesoporous silica nanoparticles (HMSNs) that can intrinsically radiolabel an oxophilic zirconium-89 (⁸⁹Zr, t_1/2 = 78.4 h) radionuclide, as well as possess great drug loading capacity, Ce6 can be activated by Cerenkov radiation from ⁸⁹Zr in the same nanoconstruct. In vitro cell viability experiments demonstrated dose-dependent cell deconstruction as a function of the concentration of Ce6 and ⁸⁹Zr. In vivo studies show inhibition of tumor growth when mice were subcutaneously injected with [⁸⁹Zr]HMSN-Ce6, and histological analysis of the tumor section showed damage to tumor tissues, implying that reactive oxygen species mediated the destruction. This study offers a way to use an internal radiation source to achieve deep-seated tumor therapy without using any external light source for future applications.

Antigen-specific immunoreactivity and clinical outcome following vaccination with glioma-associated antigen peptides in children with recurrent high-grade gliomas: results of a pilot study

Recurrent high-grade gliomas (HGGs) of childhood have an exceedingly poor prognosis with current therapies. Accordingly, new treatment approaches are needed. We initiated a pilot trial of vaccinations with peptide epitopes derived from glioma-associated antigens (GAAs) overexpressed in these tumors in HLA-A2+ children with recurrent HGG that had progressed after prior treatments. Peptide epitopes for three GAAs (EphA2, IL13Rα2, survivin), emulsified in Montanide-ISA-51, were administered subcutaneously adjacent to intramuscular injections of poly-ICLC every 3 weeks for 8 courses, followed by booster vaccines every 6 weeks. Primary endpoints were safety and T-cell responses against the GAA epitopes, assessed by enzyme-linked immunosorbent spot (ELISPOT) analysis. Treatment response was evaluated clinically and by magnetic resonance imaging. Twelve children were enrolled, 6 with glioblastoma, 5 with anaplastic astrocytoma, and one with malignant gliomatosis cerebri. No dose-limiting non-CNS toxicity was encountered. ELISPOT analysis, in ten children, showed GAA responses in 9: to IL13Rα2 in 4, EphA2 in 9, and survivin in 3. One child had presumed symptomatic pseudoprogression, discontinued vaccine therapy, and responded to subsequent treatment. One other child had a partial response that persisted throughout 2 years of vaccine therapy, and continues at >39 months. Median progression-free survival (PFS) from the start of vaccination was 4.1 months and median overall survival (OS) was 12.9 months. 6-month PFS and OS were 33 and 73 %, respectively. GAA peptide vaccination in children with recurrent malignant gliomas is generally well tolerated, and has preliminary evidence of immunological and modest clinical activity.

Tumor antigen-specific T cells for immune monitoring of dendritic cell-treated glioblastoma patients

BACKGROUND AIMS

CD8(+) T cells are part of the adaptive immune system and, as such, are responsible for the elimination of tumor cells. Dendritic cells (DC) are professional antigen-presenting cells (APC) that activate CD8(+) T cells. Effector CD8(+) T cells in turn mediate the active immunotherapeutic response of DC vaccination against the aggressive glioblastoma (GBM). The lack of tumor response assays complicates the assessment of treatment success in GBM patients.

METHODS

A novel assay to identify specific cytotoxicity of activated T cells by APC was evaluated. Tumor antigen-pulsed DCs from HLA-A*02-positive GBM patients were cultivated to stimulate autologous cytotoxic T lymphocytes (CTL) over a 12-day culture period. To directly correlate antigen specificity and cytotoxic capacity, intracellular interferon (IFN)-γ fluorescence flow cytometry-based measurements were combined with anti-GBM tumor peptide dextramer staining. IFN-γ response was quantified by real-time polymerase chain reaction (PCR), and selected GBM genes were compared with healthy human brain cDNA by single specific primer PCR characterization.

RESULTS

Using CTL of GBM patients stimulated with GBM lysate-pulsed DCs increased IFN-γ messenger RNA levels, and intracellular IFN-γ protein expression was positively correlated with specificity against GBM antigens. Moreover, the GBM peptide-specific CD8(+) T-cell response correlated with specific GBM gene expression. Following DC vaccination, GBM patients showed 10-fold higher tumor-specific signals compared with unvaccinated GBM patients.

DISCUSSION

These data indicate that GBM tumor peptide-dextramer staining of CTL in combination with intracellular IFN-γ staining may be a useful tool to acquire information on whether a specific tumor antigen has the potential to induce an immune response in vivo.

Tissue-resident dendritic cells and diseases involving dendritic cell malfunction

Dendritic cells (DCs) control immune responses and are central to the development of immune memory and tolerance. DCs initiate and orchestrate immune responses in a manner that depends on signals they receive from microbes and cellular environment. Although DCs consist mainly of bone marrow-derived and resident populations, a third tissue-derived population resides the spleen and lymph nodes (LNs), different subsets of tissue-derived DCs have been identified in the blood, spleen, lymph nodes, skin, lung, liver, gut and kidney to maintain the tolerance and control immune responses. Tissue-resident DCs express different receptors for microbe-associated molecular patterns (MAMPs) and damage-associated molecular patterns (DAMPs), which were activated to promote the production of pro- or anti-inflammatory cytokines. Malfunction of DCs contributes to diseases such as autoimmunity, allergy, and cancer. It is therefore important to update the knowledge about resident DC subsets and diseases associated with DC malfunction.

Prioritization schema for immunotherapy clinical trials in glioblastoma

BACKGROUND

Emerging immunotherapeutic strategies for the treatment of glioblastoma (GBM) such as dendritic cell (DC) vaccines, heat shock proteins, peptide vaccines, and adoptive T-cell therapeutics, to name a few, have transitioned from the bench to clinical trials. With upcoming strategies and developing therapeutics, it is challenging to critically evaluate the practical, clinical potential of individual approaches and to advise patients on the most promising clinical trials.

METHODS

The authors propose a system to prioritize such therapies in an organized and data-driven fashion. This schema is based on four categories of factors: antigenic target robustness, immune-activation and -effector responses, preclinical vetting, and early evidence of clinical response. Each of these categories is subdivided to focus on the most salient elements for developing a successful immunotherapeutic approach for GBM, and a numerical score is generated.

RESULTS

The Score Card reveals therapeutics that have the most robust data to support their use, provides a reference prioritization score, and can be applied in a reiterative fashion with emerging data.

CONCLUSIONS

The authors hope that this schema will give physicians an evidence-based and rational framework to make the best referral decisions to better guide and serve this patient population.

Preconditioning Vaccine Sites for mRNA-Transfected Dendritic Cell Therapy and Antitumor Efficacy

Messenger RNA (mRNA)-transfected dendritic cell (DC) vaccines have been shown to be a powerful modality for eliciting antitumor immune responses in mice and humans; however, their application has not been fully optimized since many of the factors that contribute to their efficacy remain poorly understood. Work stemming from our laboratory has recently demonstrated that preconditioning the vaccine site with a recall antigen prior to the administration of a dendritic cell vaccine creates systemic recall responses and resultantly enhances dendritic cell migration to the lymph nodes with improved antitumor efficacy. This chapter describes the generation of murine mRNA-transfected DC vaccines, as well as a method for vaccine site preconditioning with protein antigen formulations that create potent recall responses.

Immunotherapy with dendritic cells loaded with glioblastoma stem cells: from preclinical to clinical studies

Different approaches have been explored to raise effective antitumor responses against glioblastoma (GBM), the deadliest of primary brain tumors. In many clinical studies, cancer vaccines have been based on dendritic cells (DCs) loaded with peptides, representing one or more specific tumor antigens or whole lysates as a source of multiple antigens. Randomized clinical trials using DCs are ongoing, and results of efficacy are not yet available. Such strategies are feasible and safe; however, immune-suppressive microenvironment, absence of appropriate specific epitopes to target, and cancer immunoediting can limit their efficacy. The aim of this review is to describe how the definition of novel and more specific targets may increase considerably the possibility of successful DC immunotherapy. By proposing to target glioblastoma stem-like cells (GSCs), the immune response will be pointed to eradicating factors and pathways highly relevant to GBM biology. Preclinical observations on efficacy, and preliminary results of immunotherapy trials, encourage exploring the clinical efficacy of DC immunotherapy in GBM patients using high-purity, GSC-loaded DC vaccines.

Immunomonitoring in glioma immunotherapy: current status and future perspectives

Given the continued poor clinical outcomes and refractory nature of glioblastoma multiforme to traditional interventions, immunotherapy is gaining traction due to its potential for specific tumor-targeting and long-term antitumor protective surveillance. Currently, development of glioma immunotherapy relies on overall survival as an endpoint in clinical trials. However, the identification of surrogate immunologic biomarkers can accelerate the development of successful immunotherapeutic strategies. Immunomonitoring techniques possess the potential to elucidate immunological mechanisms of antitumor responses, monitor disease progression, evaluate therapeutic effect, identify candidates for immunotherapy, and serve as prognostic markers of clinical outcome. Current immunomonitoring assays assess delayed-type hypersensitivity, T cell proliferation, cytotoxic T-lymphocyte function, cytokine secretion profiles, antibody titers, and lymphocyte phenotypes. Yet, no single immunomonitoring technique can reliably predict outcomes, relegating immunological markers to exploratory endpoints. In response, the most recent immunomonitoring assays are incorporating emerging technologies and novel analysis techniques to approach the goal of identifying a competent immunological biomarker which predicts therapy responsiveness and clinical outcome. This review addresses the current status of immunomonitoring in glioma vaccine clinical trials with emphasis on correlations with clinical response.