Clinical Application of a Dendritic Cell Vaccine Raised Against Heat-Shocked Glioblastoma

Immunobiology and immunotherapeutic targeting of glioma stem cells

For decades human brain tumors have confounded our efforts to effectively manage and treat patients. In adults, glioblastoma multiforme is the most common malignant brain tumor with a patient survival of just over 14 months. In children, brain tumors are the leading cause of solid tumor cancer death and gliomas account for one-fifth of all childhood cancers. Despite advances in conventional treatments such as surgical resection, radiotherapy, and systemic chemotherapy, the incidence and mortality rates for gliomas have essentially stayed the same. Furthermore, research efforts into novel therapeutics that initially appeared promising have yet to show a marked benefit. A shocking and somewhat disturbing view is that investigators and clinicians may have been targeting the wrong cells, resulting in the appearance of the removal or eradication of patient gliomas only to have brain cancer recurrence. Here we review research progress in immunotherapy as it pertains to glioma treatment and how it can and is being adapted to target glioma stem cells (GSCs) as a means of dealing with this potential paradigm.

Active dendritic cell immunotherapy for glioblastoma: Current status and challenges

Dendritic cell (DC) immunotherapy is developing as a promising treatment modality for patients with glioblastoma multiforme (GBM). The aim of this article is to review the data from clinical trials and prospective studies evaluating the safety and efficacy of DC vaccines for newly diagnosed (ND)- and recurrent (Rec)-GBM and for other high-grade gliomas (HGGs). By searching all major databases we identified and reviewed twenty-two (n=22) such studies, twenty (n=20) of which were phase I and II trials, one was a pilot study towards a phase I/II trial and one was a prospective study. GBM patients were exclusively recruited in 12/22 studies, while 10/22 studies enrolled patients with any diagnosis of a HGG. In 7/22 studies GBM was newly diagnosed. In the vast majority of studies the vaccine was injected subcutaneously or intradermally and consisted of mature DCs pulsed with tumour lysate or peptides. Median overall survival ranged between 16.0 and 38.4 months for ND-GBM and between 9.6 and 35.9 months for Rec-GBM. Vaccine-related side effects were in general mild (grade I and II), with serious adverse events (grade III, IV and V) reported only rarely. DC immunotherapy therefore appears to have the potential to increase the overall survival in patients with HGG, with an acceptable side effect profile. The findings will require confirmation by the ongoing and future phase III trials.

Trial watch: Dendritic cell-based interventions for cancer therapy

Dendritic cells (DCs) occupy a central position in the immune system, orchestrating a wide repertoire of responses that span from the development of self-tolerance to the elicitation of potent cellular and humoral immunity. Accordingly, DCs are involved in the etiology of conditions as diverse as infectious diseases, allergic and autoimmune disorders, graft rejection and cancer. During the last decade, several methods have been developed to load DCs with tumor-associated antigens, ex vivo or in vivo, in the attempt to use them as therapeutic anticancer vaccines that would elicit clinically relevant immune responses. While this has not always been the case, several clinical studies have demonstrated that DC-based anticancer vaccines are capable of activating tumor-specific immune responses that increase overall survival, at least in a subset of patients. In 2010, this branch of clinical research has culminated with the approval by FDA of a DC-based therapeutic vaccine (sipuleucel-T, Provenge^®) for use in patients with asymptomatic or minimally symptomatic metastatic hormone-refractory prostate cancer. Intense research efforts are currently dedicated to the identification of the immunological features of patients that best respond to DC-based anticancer vaccines. This knowledge may indeed lead to personalized combination strategies that would extend the benefit of DC-based immunotherapy to a larger patient population. In addition, widespread enthusiasm has been generated by the results of the first clinical trials based on in vivo DC targeting, an approach that holds great promises for the future of DC-based immunotherapy. In this Trial Watch, we will summarize the results of recently completed clinical trials and discuss the progress of ongoing studies that have evaluated/are evaluating DC-based interventions for cancer therapy.

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

OBJECTIVE

Glioblastoma multiforme (GBM) has a poor prognosis. The purpose of this systematic review and meta-analysis was to analyze the outcomes of clinical trials which compared immunotherapy with conventional therapy for the treatment of malignant gliomas.

METHODS

PubMed, Cochrane and Google Scholar databases were searched for relevant studies. The 2-year survival rate was used to evaluate effectiveness of immunotherapy.

RESULTS

Of 171 studies identified, six comparative trials were included in the systematic review. Immunotherapy was associated with a significantly longer OS and 2-year survival compared to conventional therapy.

CONCLUSION

Immunotherapy may improve the survival of patients with GBM.

Clinical efficacy of tumor antigen-pulsed DC treatment for high-grade glioma patients: evidence from a meta-analysis

BACKGROUND

The effectiveness of immunotherapy for high-grade glioma (HGG) patients remains controversial. To evaluate the therapeutic efficacy of dendritic cells (DCs) alone in the treatment of HGG, we performed a systematic review and meta-analysis in terms of patient survival with relevant published clinical studies.

MATERIALS AND METHODS

A total of 409 patients, including historical cohorts, nonrandomized and randomized controls with HGG, were selected for the meta-analysis.

RESULTS

The treatment of HGG with DCs was associated with a significantly improved one-year survival (OS) (p<0.001) and 1.5-, 2-, 3-, 4-, and 5-year OS (p<0.001) compared with the non-DC group. A meta-analysis of the patient outcome data revealed that DC immunotherapy has a significant influence on progression-free survival (PFS) in HGG patients, who showed significantly improved 1-,1.5-, 2-, 3- and 4-year PFS (p<0.001). The analysis of Karnofsky performance status (KPS) demonstrated no favorable results for DC cell therapy arm (p = 0.23).The percentages of CD3+CD8+ and CD3+CD4+ T cells and CD16+ lymphocyte subset were not significantly increased in the DC group compared with the baseline levels observed before treatment (p>0.05), whereas CD56+ lymphocyte subset were significantly increased after DC treatment (p = 0.0001). Furthermore, the levels of IFN-γ in the peripheral blood of HGG patients, which reflect the immune function of the patients, were significantly increased after DC immunotherapy (p<0.001).

CONCLUSIONS

Thus, our meta-analysis showed that DC immunotherapy markedly prolongs survival rates and progression-free time, enhances immune function, and improves the efficacy of the treatment of HGG patients.

Stem cell in alternative treatments for brain tumors: potential for gene delivery

Despite ongoing research efforts and attempts to bring new drugs into trial, the prognosis for brain tumors remains poor. Patients with the most common and lethal intracranial neoplasia, glioblastoma multiforme (GBM), have an average survival of one year with combination of surgical resection, radiotherapy and temozolomide. One of the main problems in the treatment of GBM is getting drugs across the blood brain barrier (BBB) efficiently. In an attempt to solve this problem, there are ongoing experimental and clinical trials to deliver drugs within stem cells. The purpose for this method is the ease by which stem cells home to the brain. This review discusses the experimental and clinical applications of stem cells for GBM. We also discuss the different properties of stem cells. This information is important to understand why one stem cell would be advantageous over another in cell therapy. We provide an overview of the different drug delivery methods, gene-based treatments and cancer vaccines for GBM, including the stem cell subset.

Stem cell in alternative treatments for brain tumors: potential for gene delivery

Despite ongoing research efforts and attempts to bring new drugs into trial, the prognosis for brain tumors remains poor. Patients with the most common and lethal intracranial neoplasia, glioblastoma multiforme (GBM), have an average survival of one year with combination of surgical resection, radiotherapy and temozolomide. One of the main problems in the treatment of GBM is getting drugs across the blood brain barrier (BBB) efficiently. In an attempt to solve this problem, there are ongoing experimental and clinical trials to deliver drugs within stem cells. The purpose for this method is the ease by which stem cells home to the brain. This review discusses the experimental and clinical applications of stem cells for GBM. We also discuss the different properties of stem cells. This information is important to understand why one stem cell would be advantageous over another in cell therapy. We provide an overview of the different drug delivery methods, gene-based treatments and cancer vaccines for GBM, including the stem cell subset.

Clinical use of dendritic cells for cancer therapy

Since the mid-1990s, dendritic cells have been used in clinical trials as cellular mediators for therapeutic vaccination of patients with cancer. Dendritic cell-based immunotherapy is safe and can induce antitumour immunity, even in patients with advanced disease. However, clinical responses have been disappointing, with classic objective tumour response rates rarely exceeding 15%. Paradoxically, findings from emerging research indicate that dendritic cell-based vaccination might improve survival, advocating implementation of alternative endpoints to assess the true clinical potency of dendritic cell-based vaccination. We review the clinical effectiveness of dendritic cell-based vaccine therapy in melanoma, prostate cancer, malignant glioma, and renal cell carcinoma, and summarise the most important lessons from almost two decades of clinical studies of dendritic cell-based immunotherapy in these malignant disorders. We also address how the specialty is evolving, and which new therapeutic concepts are being translated into clinical trials to leverage the clinical effectiveness of dendritic cell-based cancer immunotherapy. Specifically, we discuss two main trends: the implementation of the next-generation dendritic cell vaccines that have improved immunogenicity, and the emerging paradigm of combination of dendritic cell vaccination with other cancer therapies.

Immunotherapy for high-grade glioma: how to go beyond Phase I/II clinical trials

Evaluation of: Lasky JL 3rd, Panosyan EH, Plant A et al. Autologous tumor lysate-pulsed dendritic cell immunotherapy for pediatric patients with newly diagnosed or recurrent high-grade gliomas. Anticancer Res. 33, 2047-2056 (2013). Immunotherapy for children and adults with high-grade glioma (HGG) is an emerging innovative treatment approach, which aims at stimulating the body's own immune system against HGG by using autologous dendritic cells pulsed with autologous tumor lysate as a therapeutic vaccine. This is the third report on immunotherapy for HGG in children, bringing additional knowledge and experience to the scientific community. However, at the same time, this and other manuscripts urge for the next step in treatment development.

A review of dendritic cell therapy for cancer: progress and challenges

Dendritic cells are the professional antigen-presenting cells of the innate immune system with the potential to generate robust antigen-specific T cell immune responses. Immunotherapeutic strategies have attempted to monopolize on this ability of dendritic cells to deliver antigens as a means of therapeutic vaccination in individuals with advanced malignancies. Since the publication of the first clinical trial in melanoma patients in 1995, therapeutic dendritic cell cancer vaccines have been extensively studied in numerous phase I and II trials. While advances have been encountered (especially with prostate cancer), there are still considerable challenges that need to be addressed in future clinical trials. In this review, we describe the current methodology and highlight trials which have contributed to the development of dendritic cell vaccines. We then review strategies to optimize dendritic cell vaccines in order to improve antitumor responses in cancer patients.

Cytokine responsiveness of CD8(+) T cells is a reproducible biomarker for the clinical efficacy of dendritic cell vaccination in glioblastoma patients

Background

Immunotherapeutic approaches, such as dendritic cell (DC) vaccination, have emerged as promising strategies in the treatment of glioblastoma. Despite their promise, however, the absence of objective biomarkers and/or immunological monitoring techniques to assess the clinical efficacy of immunotherapy still remains a primary limitation. To address this, we sought to identify a functional biomarker for anti-tumor immune responsiveness associated with extended survival in glioblastoma patients undergoing DC vaccination.

Methods

28 patients were enrolled and treated in two different Phase 1 DC vaccination clinical trials at UCLA. To assess the anti-tumor immune response elicited by therapy, we studied the functional responsiveness of pre- and post-vaccination peripheral blood lymphocytes (PBLs) to the immunostimulatory cytokines interferon-gamma (IFN-γ) and interleukin-2 (IL-2) in 21 of these patients for whom we had adequate material. Immune responsiveness was quantified by measuring downstream phosphorylation events of the transcription factors, STAT-1 and STAT-5, via phospho-specific flow cytometry.

Results

DC vaccination induced a significant decrease in the half-maximal concentration (EC-50) of IL-2 required to upregulate pSTAT-5 specifically in CD3⁺CD8⁺ T lymphocytes (p < 0.045). Extended survival was also associated with an increased per cell phosphorylation of STAT-5 in cytotoxic T-cells following IL-2 stimulation when the median post/pre pSTAT-5 ratio was used to dichotomize the patients (p = 0.0015, log-rank survival; hazard ratio = 0.1834, p = 0.018). Patients whose survival was longer than two years had a significantly greater pSTAT-5 ratio (p = 0.015), but, contrary to our expectations, a significantly lower pSTAT-1 ratio (p = 0.038).

Conclusions

Our results suggest that monitoring the pSTAT signaling changes in PBL may provide a functional immune monitoring measure predictive of clinical efficacy in DC-vaccinated patients.

Fractionated radiotherapy is the main stimulus for the induction of cell death and of Hsp70 release of p53 mutated glioblastoma cell lines

Background

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. Despite a multimodal therapy consisting of resection followed by fractionated radiotherapy (RT) combined with the chemotherapeutic agent (CT) temozolomide (TMZ), its recurrence is almost inevitable. Since the immune system is capable of eliminating small tumor masses, a therapy should also aim to stimulate anti-tumor immune responses by induction of immunogenic cell death forms. The histone deacetylase inhibitor valproic acid (VPA) might foster this.

Methods

Reflecting therapy standards, we applied in our in vitro model fractionated RT with a single dose of 2Gy and clinically relevant concentrations of CT. Not only the impact of RT and/or CT with TMZ and/or VPA on the clonogenic potential and cell cycle of the glioblastoma cell lines T98G, U251MG, and U87MG was analyzed, but also the resulting cell death forms and release of danger signals such as heat-shock protein70 (Hsp70) and high-mobility group protein B1 (HMGB1).

Results

The clonogenic assays revealed that T98G and U251MG, having mutated tumor suppressor protein p53, are more resistant to RT and CT than U87MG with wild type (WT) p53. In all glioblastoma cells lines, fractionated RT induced a G2 cell cycle arrest, but only in the case of U87MG, TMZ and/or VPA alone resulted in this cell cycle block. Further, fractionated RT significantly increased the number of apoptotic and necrotic tumor cells in all three cell lines. However, only in U87MG, the treatment with TMZ and/or VPA alone, or in combination with fractionated RT, induced significantly more cell death compared to untreated or irradiated controls. While necrotic glioblastoma cells were present after VPA, TMZ especially led to significantly increased amounts of U87MG cells in the radiosensitive G2 cell cycle phase. While CT did not impact on the release of Hsp70, fractionated RT resulted in significantly increased extracellular concentrations of Hsp70 in p53 mutated and WT glioblastoma cells.

Conclusions

Our results indicate that fractionated RT is the main stimulus for induction of glioblastoma cell death forms with immunogenic potential. The generated tumor cell microenvironment might be beneficial to include immune therapies for GBM in the future.

Dendritic cell vaccination for glioblastoma multiforme: review with focus on predictive factors for treatment response

Glioblastoma multiforme (GBM) is the most common and most aggressive type of primary brain cancer. Since median overall survival with multimodal standard therapy is only 15 months, there is a clear need for additional effective and long-lasting treatments. Dendritic cell (DC) vaccination is an experimental immunotherapy being tested in several Phase I and Phase II clinical trials. In these trials, safety and feasibility have been proven, and promising clinical results have been reported. On the other hand, it is becoming clear that not every GBM patient will benefit from this highly personalized treatment. Defining the subgroup of patients likely to respond to DC vaccination will position this option correctly amongst other new GBM treatment modalities, and pave the way to incorporation in standard therapy. This review provides an overview of GBM treatment options and focuses on the currently known prognostic and predictive factors for response to DC vaccination. In this way, it will provide the clinician with the theoretical background to refer patients who might benefit from this treatment.

Clinical trials in cellular immunotherapy for brain/CNS tumors

High-grade gliomas are the most common type of primary malignant brain/CNS tumor. There have been only modest advances in surgical techniques, radiotherapy and chemotherapy for high-grade gliomas over the past several decades. None of these have provided a major improvement in survival for patients. Recently, immunotherapy has been explored for the treatment of high-grade gliomas. Immunotherapy capitalizes on the specificity of the host immune system to selectively target tumor cells for destruction, while sparing normal brain parenchyma, thus making it a particularly attractive option. This article provides a comprehensive review of published clinical trials evaluating cellular immunotherapy in primary brain/CNS tumors.

Vaccine-based immunotherapy for glioblastoma

Glioblastoma remains the most lethal human brain tumor, despite the advent of multimodal treatment approaches. Because immune tolerance plays an important role in tumor progression, adding immunotherapy has become an attractive and innovative treatment approach for these aggressive tumors. Several early-phase clinical trials have demonstrated that vaccine-based immunotherapies, including dendritic cell therapy, peptide-based vaccines and vaccines containing autologous tumor lysates, are feasible and well tolerated. These trials have revealed promising trends in overall survival and progression-free survival for patients with glioblastoma, and have paved the way for ongoing randomized controlled trials.

Active immunotherapy using dendritic cells in the treatment of glioblastoma multiforme

OBJECTIVE

Glioblastoma multiforme, the most common malignant brain tumor still has a dismal prognosis with conventional treatment. Therefore, it is necessary to explore new and/or adjuvant treatment options to improve patient outcomes. Active immunotherapy is a new area of research that may be a successful treatment option. The focus is on vaccines that consist of antigen presenting cells (APCs) loaded with tumor antigen. We have conducted a systematic review of prospective studies, case reports and clinical trials. The goal of this study was to examine the efficacy and safety in terms of complications, median overall survival (OS), progression free survival (PFS) and quality of life.

METHODS

A PubMed search was performed to include all relevant studies that reported the characteristics, outcomes and complications of patients with GBM treated with active immunotherapy using dendritic cells. Reported parameters were immune response, radiological findings, median PFS and median OS. Complications were categorized based on association with the craniotomy or with the vaccine itself.

RESULTS

A total of 21 studies with 403 patients were included in our review. Vaccination with dendritic cells (DCs) loaded with autologous tumor cells resulted in increased median OS in patients with recurrent GBM (71.6-138.0 wks) as well as those newly diagnosed (65.0-230.4 wks) compared to average survival of 58.4 wks.

CONCLUSIONS

Active immunotherapy, specifically with autologous DCs loaded with autologous tumor cells, seems to have the potential of increasing median OS and prolonged tumor PFS with minimal complications. Larger clinical trials are needed to show the potential benefits of active immunotherapy.

Dendritic cell vaccination in pediatric gliomas: lessons learnt and future perspectives

Immunotherapy of malignant gliomas with autologous dendritic cells (DCs) in addition to surgery and radiochemotherapy has been a focus of intense research during the past decade. Since both children and adults are affected by this highly aggressive brain tumor, 10-15% of the several hundred vaccinated patients represent children, making pediatric glioma patients the largest uniform pediatric vaccination cohort so far. In general, DC vaccination in malignant gliomas has been shown to be safe and several studies with a non-vaccinated control group could clearly demonstrate a survival benefit for the vaccinated patients. Interestingly, children and adolescents below 21 years of age seem to benefit even more than adult patients. This review summarizes the findings of the 25 clinical trials published so far and gives a perspective how DC vaccination could be implemented as part of multimodal therapeutic strategies in the near future.