A randomized, double-blind, phase III trial of personalized peptide vaccination for recurrent glioblastoma

Identifying the best treatment choice for relapsing/refractory glioblastoma: a systematic review with multiple Bayesian network meta-analyses

BACKGROUND

Glioblastoma is a highly aggressive primary central nervous system tumor characterized by poor outcomes. In case of relapse or progression to adjuvant chemotherapy, there is no univocal preferred regimen for relapsing glioblastoma.

METHODS

We conducted a systematic review and Bayesian trial-level network meta-analyses (NMA) to identify the regimens associated with the best outcomes. The primary endpoint was overall survival (OS). Secondary endpoints were progression-free survival (PFS) and overall response rates (ORR). We estimated separate treatment rankings based on the surface under the cumulative ranking curve values. Only phase II/III prospective comparative trials were included.

RESULTS

Twenty-four studies (3733 patients and 27 different therapies) were ultimately included. Twenty-three different regimens were compared for OS, 21 for PFS, and 26 for ORR. When taking lomustine as a common comparator, only regorafenib was likely to be significantly superior in terms of OS (hazard ratio: 0.50, 95% credible interval: 0.33-0.75). Regorafenib was significantly superior to other 16 (69.6%) regimens, including NovoTTF-100A, bevacizumab monotherapy, and several bevacizumab-based combinations. Regarding PFS and ORR, no treatment was clearly superior to the others.

CONCLUSIONS

This NMA supports regorafenib as one of the best available options for relapsing/refractory glioblastoma. Lomustine, NovoTTF-100A, and bevacizumab emerge as other viable alternative regimens. However, evidence on regorafenib is controversial at best. Moreover, most studies were underpowered, with varying inclusion criteria and primary endpoints, and no longer adapted to the most recent glioblastoma classification. A paradigmatic change in clinical trials' design for relapsing/refractory glioblastoma and more effective treatments are urgently required.

Immunotherapy for glioblastoma: current state, challenges, and future perspectives

Glioblastoma (GBM) is an aggressive and lethal type of brain tumor in human adults. The standard of care offers minimal clinical benefit, and most GBM patients experience tumor recurrence after treatment. In recent years, significant advancements have been made in the development of novel immunotherapies or other therapeutic strategies that can overcome immunotherapy resistance in many advanced cancers. However, the benefit of immune-based treatments in GBM is limited because of the unique brain immune profiles, GBM cell heterogeneity, and immunosuppressive tumor microenvironment. In this review, we present a detailed overview of current immunotherapeutic strategies and discuss the challenges and potential molecular mechanisms underlying immunotherapy resistance in GBM. Furthermore, we provide an in-depth discussion regarding the strategies that can overcome immunotherapy resistance in GBM, which will likely require combination therapies.

Vaccine-based immunotherapy and related preclinical models for glioma

Glioma, the most common primary malignant tumor in the central nervous system (CNS), lacks effective treatments, and >60% of cases are glioblastoma (GBM), the most aggressive form. Despite advances in immunotherapy, GBM remains highly resistant. Approaches that target tumor antigens expedite the development of immunotherapies, including personalized tumor-specific vaccines, patient-specific target selection, dendritic cell (DC) vaccines, and chimeric antigen receptor (CAR) and T cell receptor (TCR) T cells. Recent studies show promising results in treating GBM and lower-grade glioma (LGG), fostering hope for future immunotherapy. This review discusses tumor vaccines against glioma, preclinical models in immunological research, and the role of CD4+ T cells in vaccine-induced antitumor immunity. We also summarize clinical approaches, challenges, and future research for creating more effective vaccines.

Clinical and translational advances in primary brain tumor therapy with a focus on glioblastoma-A comprehensive review of the literature

This comprehensive review paper examines the most updated state of research on glioblastoma, an aggressive brain tumor with limited treatment options. By analyzing 76 recent studies, from translational and basic sciences, to clinical trials, we highlight various aspects of glioblastoma and shed light on potential therapeutic strategies. The interplay between tumor cells, neural progenitor cells, and the tumor microenvironment is explored. Targeting the PI3K-Akt-mTOR pathway through extracellular-vesicle (EV)-mediated signaling emerges as a potential therapeutic strategy. Personalized modeling approaches utilizing patient-specific MRI data offer promise for optimizing treatment strategies. The response of glioblastoma stem cells (GSCs) to different treatment modalities is examined, emphasizing the need to inhibit the transformation of proneural (PN) GSCs into resistant mesenchymal (MES) GSCs. Metabolic therapy and combination therapies show potential in reversing treatment resistance and inhibiting both PN and MES GSCs. Immunotherapy, targeted approaches, and molecular dynamics in gliomas are discussed, providing insights into early-stage diagnosis and treatment. Additionally, the potential use of Zika virus as an oncolytic agent is explored. Analysis of phase 0 to 3 clinical trials reveal promising outcomes for various experimental treatments, highlighting the importance of combination therapies, predictive signatures, and patient selection strategies. Specific compounds demonstrate potential therapeutic benefits and tolerability. Phase 3 trials indicate the efficacy of DCVax-L in improving survival rates and depatux-m in prolonging progression-free survival. These findings emphasize the importance of personalized treatment approaches and continued exploration of targeted therapies, immunotherapies, and tumor biology understanding in shaping the future of glioblastoma treatment.

Approaches in Adult Glioblastoma Treatment: A Systematic Review of Emerging Therapies

Glioblastoma (GB) is the most common and aggressive primary brain tumor in adults, characterized by complex genetic changes and a poor prognosis. Current standard therapies, including surgery, chemotherapy, and radiotherapy, have limited effectiveness. Emerging therapeutic strategies aim to address the high recurrence rate and improve outcomes by targeting glioblastoma stem cells (GSCs), the blood-brain barrier, and utilizing advanced drug delivery systems. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. An electronic search was conducted across several databases, including PubMed, Embase, Scopus, Web of Science, and Cochrane, covering studies published from January 2019 to May 2024. The inclusion criteria encompassed primary research studies in English focusing on emerging therapies for treating GB in adults. Eligible studies included experimental and observational studies. Only peer-reviewed journal articles were considered. Exclusion criteria included non-human studies, pediatric studies, non-peer-reviewed articles, systematic reviews, case reports, conference abstracts, and editorials. The search identified 755 articles and, finally, 24 of them met the inclusion criteria. The key findings highlight various promising therapies. Despite advances in treatment approaches, the complexity and heterogeneity of GB necessitate ongoing research to optimize these innovative strategies. The study has limitations that should be considered. The inclusion of only English-language articles may introduce language bias, and the focus on peer-reviewed articles could exclude valuable data from non-peer-reviewed sources. Heterogeneity among studies, particularly in sample sizes and designs, complicates comparison and synthesis, while the reliance on preclinical models limits generalizability to clinical practice. Nonetheless, this review provides a comprehensive overview of the emerging therapies that hold promise for improving patient outcomes in GB treatment.

Biomarkers of immunotherapy in glioblastoma

Glioblastoma (GBM) is the most common primary brain cancer, comprising half of all malignant brain tumors. Patients with GBM have a poor prognosis, with a median survival of 14-15 months. Current therapies for GBM, including chemotherapy, radiotherapy, and surgical resection, remain inadequate. Novel therapies are required to extend patient survival. Although immunotherapy has shown promise in other cancers, including melanoma and non-small lung cancer, its efficacy in GBM has been limited to subsets of patients. Identifying biomarkers of immunotherapy response in GBM could help stratify patients, identify new therapeutic targets, and develop more effective treatments. This article reviews existing and emerging biomarkers of clinical response to immunotherapy in GBM. The scope of this review includes immune checkpoint inhibitor and antitumoral vaccination approaches, summarizing the variety of molecular, cellular, and computational methodologies that have been explored in the setting of anti-GBM immunotherapies.

Metabolic Plasticity of Glioblastoma Cells in Response to DHODH Inhibitor BAY2402234 Treatment

Glioblastoma (IDH-wildtype) represents a formidable challenge in oncology, lacking effective chemotherapeutic or biological interventions. The metabolic reprogramming of cancer cells is a hallmark of tumor progression and drug resistance, yet the role of metabolic reprogramming in glioblastoma during drug treatment remains poorly understood. The dihydroorotate dehydrogenase (DHODH) inhibitor BAY2402234 is a blood-brain barrier penetrant drug showing efficiency in in vivo models of many brain cancers. In this study, we investigated the effect of BAY2402234 in regulating the metabolic phenotype of EGFRWT and EGFRvIII patient-derived glioblastoma cell lines. Our findings reveal the selective cytotoxicity of BAY2402234 toward EGFRWT glioblastoma subtypes with minimal effect on EGFRvIII patient cells. At sublethal doses, BAY2402234 induces triglyceride synthesis at the expense of membrane lipid synthesis and fatty acid oxidation in EGFRWT glioblastoma cells, while these effects are not observed in EGFRvIII glioblastoma cells. Furthermore, BAY2402234 reduced the abundance of signaling lipid species in EGFRWT glioblastoma. This study elucidates genetic mutation-specific metabolic plasticity and efficacy in glioblastoma cells in response to drug treatment, offering insights into therapeutic avenues for precision medicine approaches.

Mutations in glioblastoma proteins do not disrupt epitope presentation and recognition, maintaining a specific CD8 T cell immune response potential

Antigen-specific cytotoxic CD8 T cells are extremely effective in controlling tumor growth and have been the focus of immunotherapy approaches. We leverage in silico tools to investigate whether the occurrence of mutations in proteins previously described as immunogenic and highly expressed by glioblastoma multiforme (GBM), such as Epidermal Growth Factor Receptor (EGFR), Isocitrate Dehydrogenase 1 (IDH1), Phosphatase and Tensin homolog (PTEN) and Tumor Protein 53 (TP53), may be contributing to the differential presentation of immunogenic epitopes. We recovered Class I MHC binding information from wild-type and mutated proteins using the Immune Epitope Database (IEDB). After that, we built peptide-MHC (pMHC-I) models in HLA-arena, followed by hierarchical clustering analysis based on electrostatic surface features from each complex. We identified point mutations that are determinants for the presentation of a set of peptides from TP53 protein. We point to structural features in the pMHC-I complexes of wild-type and mutated peptides, which may play a role in the recognition of CD8 T cells. To further explore these features, we performed 100 ns molecular dynamics simulations for the peptide pairs (wt/mut) selected. In pursuit of novel therapeutic targets for GBM treatment, we selected peptides where our predictive results indicated that mutations would not disrupt epitope presentation, thereby maintaining a specific CD8 T cell immune response. These peptides hold potential for future GBM interventions, including peptide-based or mRNA vaccine development applications.

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.

Tumor neoantigens and tumor immunotherapies

As a high-risk group of patients with cancer, the elderly exhibit limited efficacy with traditional treatments. Immunotherapy emerges as a promising adjunctive therapeutic approach that holds potential in addressing the needs of geriatric patients with cancer. Neoantigens, a unique class of tumor-specific antigens generated by non-synonymous mutations, are garnering increasing attention as targets for immunotherapy in clinical applications. Newly developed technologies, such as second-generation gene sequencing and mass spectrometry, have provided powerful technical support for the identification and prediction of neoantigens. At present, neoantigen-based immunotherapy has been extensively applied in clinical trials and has demonstrated both safety and efficacy, marking the beginning of a new era for cancer immunotherapy. This article reviews the conception, classification, inducers, and screening process of tumor neoantigens, as well as the application prospects and combination therapy strategies of neoantigen-based cancer immunotherapy.

Immunotherapeutic Strategies for the Treatment of Glioblastoma: Current Challenges and Future Perspectives

Despite decades of research and the best up-to-date treatments, grade 4 Glioblastoma (GBM) remains uniformly fatal with a patient median overall survival of less than 2 years. Recent advances in immunotherapy have reignited interest in utilizing immunological approaches to fight cancer. However, current immunotherapies have so far not met the anticipated expectations, achieving modest results in their journey from bench to bedside for the treatment of GBM. Understanding the intrinsic features of GBM is of crucial importance for the development of effective antitumoral strategies to improve patient life expectancy and conditions. In this review, we provide a comprehensive overview of the distinctive characteristics of GBM that significantly influence current conventional therapies and immune-based approaches. Moreover, we present an overview of the immunotherapeutic strategies currently undergoing clinical evaluation for GBM treatment, with a specific emphasis on those advancing to phase 3 clinical studies. These encompass immune checkpoint inhibitors, adoptive T cell therapies, vaccination strategies (i.e., RNA-, DNA-, and peptide-based vaccines), and virus-based approaches. Finally, we explore novel innovative strategies and future prospects in the field of immunotherapy for GBM.

Cancer vaccines in the clinic

Vaccines are an important tool in the rapidly evolving repertoire of immunotherapies in oncology. Although cancer vaccines have been investigated for over 30 years, very few have achieved meaningful clinical success. However, recent advances in areas such antigen identification, formulation development and manufacturing, combination therapy regimens, and indication and patient selection hold promise to reinvigorate the field. Here, we provide a timely update on the clinical status of cancer vaccines. We identify and critically analyze 360 active trials of cancer vaccines according to delivery vehicle, antigen type, indication, and other metrics, as well as highlight eight globally approved products. Finally, we discuss current limitations and future applications for clinical translation of cancer vaccines.

Immunotherapy: Advancing glioblastoma treatment-A narrative review of scientific studies

BACKGROUND

Glioblastoma (GB) is an aggressive and deadly brain tumor with a poor prognosis despite the current standard of care, including surgery, radiation, and chemotherapy.

RECENT FINDINGS

In recent years, there has been increasing interest in the potential of immunotherapies, seen to be effective in treating other cancers, in the treatment of GB. This comprehensive review presents an in-depth analysis of the remarkable progress of immunotherapy in GB treatment, focusing on human clinical studies. It also analyzes the current findings, challenges, and limitations that underscore the transformative potential of immunotherapy in managing GB. Of particular significance, it delves into the intriguing interaction of the human microbiome with immunotherapy as a novel avenue for enhancing treatment outcomes of GB.

CONCLUSION

This study sheds light on the complex GB therapy landscape and the cutting-edge strategies that show promise for enhancing patient prognosis.

Neurotoxicity of Cancer Immunotherapies Including CAR T Cell Therapy

PURPOSE OF REVIEW

To outline the spectrum of neurotoxicity seen with approved immunotherapies and in pivotal clinical trials including immune checkpoint inhibitors, chimeric antigen receptor T-cell therapy, vaccine therapy, and oncolytic viruses.

RECENT FINDINGS

There has been an exponential growth in new immunotherapies, which has transformed the landscape of oncology treatment. With more widespread use of cancer immunotherapies, there have also been advances in characterization of its associated neurotoxicity, research into potential underlying mechanisms, and development of management guidelines. Increasingly, there is also mounting interest in long-term neurologic sequelae. Neurologic complications of immunotherapy can impact every aspect of the central and peripheral nervous system. Early recognition and treatment are critical. Expanding indications for immunotherapy to solid and CNS tumors has led to new challenges, such as how to reliably distinguish neurotoxicity from disease progression. Our evolving understanding of immunotherapy neurotoxicity highlights important areas for future research and the need for novel immunomodulatory therapeutics.

Recent advances and applications of peptide-agent conjugates for targeting tumor cells

BACKGROUND

Cancer, being a complex disease, presents a major challenge for the scientific and medical communities. Peptide therapeutics have played a significant role in different medical practices, including cancer treatment.

METHOD

This review provides an overview of the current situation and potential development prospects of anticancer peptides (ACPs), with a particular focus on peptide vaccines and peptide-drug conjugates for cancer treatment.

RESULTS

ACPs can be used directly as cytotoxic agents (molecularly targeted peptides) or can act as carriers (guiding missile) of chemotherapeutic agents and radionuclides by specifically targeting cancer cells. More than 60 natural and synthetic cationic peptides are approved in the USA and other major markets for the treatment of cancer and other diseases. Compared to traditional cancer treatments, peptides exhibit anticancer activity with high specificity and the ability to rapidly kill target cancer cells. ACP's target and kill cancer cells via different mechanisms, including membrane disruption, pore formation, induction of apoptosis, necrosis, autophagy, and regulation of the immune system. Modified peptides have been developed as carriers for drugs, vaccines, and peptide-drug conjugates, which have been evaluated in various phases of clinical trials for the treatment of different types of solid and leukemia cancer.

CONCLUSIONS

This review highlights the potential of ACPs as a promising therapeutic option for cancer treatment, particularly through the use of peptide vaccines and peptide-drug conjugates. Despite the limitations of peptides, such as poor metabolic stability and low bioavailability, modified peptides show promise in addressing these challenges. Various mechanism of action of anticancer peptides. Modes of action against cancer cells including: inducing apoptosis by cytochrome c release, direct cell membrane lysis (necrosis), inhibiting angiogenesis, inducing autophagy-mediated cell death and immune cell regulation.

Glioblastoma Immunotherapy: A Systematic Review of the Present Strategies and Prospects for Advancements

Glioblastoma (GBM) is characterized by aggressive growth and high rates of recurrence. Despite the advancements in conventional therapies, the prognosis for GBM patients remains poor. Immunotherapy has recently emerged as a potential treatment option. The aim of this systematic review is to assess the current strategies and future perspectives of the GBM immunotherapy strategies. A systematic search was conducted across major medical databases (PubMed, Embase, and Cochrane Library) up to 3 September 2023. The search strategy utilized relevant Medical Subject Heading (MeSH) terms and keywords related to "glioblastomas," "immunotherapies," and "treatment." The studies included in this review consist of randomized controlled trials, non-randomized controlled trials, and cohort studies reporting on the use of immunotherapies for the treatment of gliomas in human subjects. A total of 1588 papers are initially identified. Eligibility is confirmed for 752 articles, while 655 are excluded for various reasons, including irrelevance to the research topic (627), insufficient method and results details (12), and being case-series or cohort studies (22), systematic literature reviews, or meta-analyses (3). All the studies within the systematic review were clinical trials spanning from 1995 to 2023, involving 6383 patients. Neuro-oncology published the most glioma immunotherapy-related clinical trials (15/97, 16%). Most studies were released between 2018 and 2022, averaging nine publications annually during this period. Adoptive cellular transfer chimeric antigen receptor (CAR) T cells were the primary focus in 11% of the studies, with immune checkpoint inhibitors (ICIs), oncolytic viruses (OVs), and cancer vaccines (CVs) comprising 26%, 12%, and 51%, respectively. Phase-I trials constituted the majority at 51%, while phase-III trials were only 7% of the total. Among these trials, 60% were single arm, 39% double arm, and one multi-arm. Immunotherapies were predominantly employed for recurrent GBM (55%). The review also revealed ongoing clinical trials, including 9 on ICIs, 7 on CVs, 10 on OVs, and 8 on CAR T cells, totaling 34 trials, with phase-I trials representing the majority at 53%, and only one in phase III. Overcoming immunotolerance, stimulating robust tumor antigen responses, and countering immunosuppressive microenvironment mechanisms are critical for curative GBM immunotherapy. Immune checkpoint inhibitors, such as PD-1 and CTLA-4 inhibitors, show promise, with the ongoing research aiming to enhance their effectiveness. Personalized cancer vaccines, especially targeting neoantigens, offer substantial potential. Oncolytic viruses exhibited dual mechanisms and a breakthrough status in the clinical trials. CAR T-cell therapy, engineered for specific antigen targeting, yields encouraging results, particularly against IL13 Rα2 and EGFRvIII. The development of second-generation CAR T cells with improved specificity exemplifies their adaptability.

Recurrent Glioblastoma: A Review of the Treatment Options

Glioblastoma is a disease with a poor prognosis. Multiple efforts have been made to improve the long-term outcome, but the 5-year survival rate is still 5-10%. Recurrence of the disease is the usual way of progression. In this situation, there is no standard treatment. Different treatment options can be considered. Among them would be reoperation or reirradiation. There are different studies that have assessed the impact on survival and the selection of patients who may benefit most from these strategies. Chemotherapy treatments have also been considered in several studies, mainly with alkylating agents, with data mostly from phase II studies. On the other hand, multiple studies have been carried out with target-directed treatments. Bevacizumab, a monoclonal antibody with anti-angiogenic activity, has demonstrated activity in several studies, and the FDA has approved it for this indication. Several other TKI drugs have been evaluated in this setting, but no clear benefit has been demonstrated. Immunotherapy treatments have been shown to be effective in other types of tumors, and several studies have evaluated their efficacy in this disease, both immune checkpoint inhibitors, oncolytic viruses, and vaccines. This paper reviews data from different studies that have evaluated the efficacy of different forms of relapsed glioblastoma.

Should Redo Surgery be Offered to Patients with Relapsed Glioblastoma? - Outcome Analyses of a Single Institution Comparative Cohort Study

BACKGROUND

Glioblastoma multiforme (GBM) is the predominant malignant brain tumor originating intracranially. The established first-line treatment postsurgery is concurrent chemoradiation as a definitive measure. However, recurrent GBM's pose a challenge for clinicians who rely on institutional experience to determine the most suitable course of action. Second-line chemotherapy may be administered with or without surgery depending on the institution's practice. This study aims to present our tertiary center institution's experience with recurrent GBM patients who underwent redo surgery.

METHODS

In this retrospective study we analyzed the surgical and oncological data of patients with recurrent GBM who underwent redo surgery at the Royal Stoke University Hospitals between 2006 and 2015. The group 1 (G1) comprised the reviewed patients, while a control group (G2) was randomly selected, matching the reviewed group by age, primary treatment, and progression-free survival (PFS). The study collected data on various parameters, including overall survival, PFS, extent of surgical resection, and postoperative complications.

RESULTS

This retrospective study included 30 patients in G1 and 32 patients in G2, matched based on age, primary treatment, and PFS. The study found that the overall survival for the G1 group from the time of first diagnosis was 109 weeks (45-180) compared to 57 weeks (28-127) in the G2 group. The incidence of postoperative complications after the second surgery was 57%, which included hemorrhage, infarction, worsening neurology due to edema, cerebrospinal fluid leak, and wound infection. Furthermore, 50% of the patients in the G1 group who underwent redo surgery received second-line chemotherapy.

CONCLUSIONS

Our study found that redo surgery for recurrent GBM is a viable treatment option for a select group of patients with good performance status, longer PFS from primary treatment, and compressive symptoms. However, the use of redo surgery varies depending on the institution. A well-designed randomized controlled trial in this population would help establish the standard of surgical care.

Clinical Applications of Immunotherapy for Recurrent Glioblastoma in Adults

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Despite standard therapies, including resection and chemoradiation, recurrence is virtually inevitable. Current treatment for recurrent glioblastoma (rGBM) is rapidly evolving, and emerging therapies aimed at targeting primary GBM are often first tested in rGBM to demonstrate safety and feasibility, which, in recent years, has primarily been in the form of immunotherapy. The purpose of this review is to highlight progress in clinical trials of immunotherapy for rGBM, including immune checkpoint blockade, oncolytic virotherapy, chimeric antigen receptor (CAR) T-cell therapy, cancer vaccine and immunotoxins. Three independent reviewers covered literature, published between the years 2000 and 2022, in various online databases. In general, the efficacy of immunotherapy in rGBM remains uncertain, and is limited to subsets/small cohorts of patients, despite demonstrating feasibility in early-stage clinical trials. However, considerable progress has been made in understanding the mechanisms that may preclude rGBM patients from responding to immunotherapy, as well as in developing new approaches/combination strategies that may inspire optimism for the utility of immunotherapy in this devastating disease. Continued trials are necessary to further assess the best therapeutic avenues and ascertain which treatments might benefit each patient individually.

Immunotherapy for Recurrent Glioma-From Bench to Bedside

Glioma is the most aggressive malignant tumor of the central nervous system, and most patients suffer from a recurrence. Unfortunately, recurrent glioma often becomes resistant to established chemotherapy and radiotherapy treatments. Immunotherapy, a rapidly developing anti-tumor therapy, has shown a potential value in treating recurrent glioma. Multiple immune strategies have been explored. The most-used ones are immune checkpoint blockade (ICB) antibodies, which are barely effective in monotherapy. However, when combined with other immunotherapy, especially with anti-angiogenesis antibodies, ICB has shown encouraging efficacy and enhanced anti-tumor immune response. Oncolytic viruses and CAR-T therapies have shown promising results in recurrent glioma through multiple mechanisms. Vaccination strategies and immune-cell-based immunotherapies are promising in some subgroups of patients, and multiple new tumor antigenic targets have been discovered. In this review, we discuss current applicable immunotherapies and related mechanisms for recurrent glioma, focusing on multiple preclinical models and clinical trials in the last 5 years. Through reviewing the current combination of immune strategies, we would like to provide substantive thoughts for further novel therapeutic regimes treating recurrent glioma.

DCVax-L Vaccination in Patients with Glioblastoma: Real Promise or Negative Trial? The Debate Is Open

The lack of significant improvement in the prognosis of patients with GB over the last decades highlights the need for innovative treatments aimed at fighting this malignancy and increasing survival outcomes. The results of the phase III clinical trial of DCVax-L (autologous tumor lysate-loaded dendritic cell vaccination), which has been shown to increase both median survival and long-term survival in newly diagnosed and relapsed glioblastoma, have been enthusiastically received by the scientific community. However, this study deserves some reflections regarding methodological issues related to the primary endpoint change, the long accrual period, and the suboptimal validity of the external control population used as the comparison arm.

Recent advances and future challenges of tumor vaccination therapy for recurrent glioblastoma

Glioblastoma (GBM) is the most malignant CNS tumor with a highest incidence rate, and most patients would undergo a recurrence. Recurrent GBM (rGBM) shows an increasing resistance to chemotherapy and radiotherapy, leading to a significantly poorer prognosis and the urgent need for novel treatments. Immunotherapy, a rapidly developing anti-tumor therapy in recent years, has shown its potential value in rGBM. Recent studies on PD-1 immunotherapy and CAR-T therapy have shown some efficacy, but the outcome was not as expected. Tumor vaccination is the oldest approach of immunotherapies, which has returned to the research focus because of the failure of other strategies and subversive understanding of CNS. The isolation effect of blood brain barrier and the immunosuppressive cell infiltration could lead to resistance existing in all phases of the anti-tumor immune response, where novel tumor vaccines have been designed to overcome these problems through new tumor antigenic targets and regulatory of the systematic immune response. In this review, the immunological characteristics of CNS and GBM would be discussed and summarized, as well as the mechanism of each novel tumor vaccine for rGBM. And through the review of completed early-phase studies and ongoing large-scale phase III clinical trials, evaluation could be conducted for potential immune response, biosecurity and initial clinical outcome, which further draw a panorama of this vital research field and provide some deep thoughts for the prospective tendency of vaccination strategy. Video Abstract.

Progress in phase III clinical trials of molecular targeted therapy and immunotherapy for glioblastoma

Glioblastoma (GBM) is the most common primary central nervous system tumor, whose prognosis remains poor under the sequential standard of care, such as neurosurgery followed by concurrent temozolomide radiochemotherapy and adjuvant temozolomide chemotherapy in the presence or absence of tumor treating fields. Accordingly, the advent of molecular targeted therapy and immunotherapy has opened a new era of tumor management. A diverse range of targeted drugs have been tested in patients with GBM in phase III clinical trials. However, these drugs are ineffective for all patients, as evidenced by the fact that only a minority of patients in these trials showed prolonged survival. Furthermore, there are several published phase III clinical trials that involve immune checkpoint inhibitors, peptide vaccines, dendritic cell vaccines, and virotherapy. Accordingly, this review comprehensively overviews existing studies of targeted drugs and immunotherapy for glioma and discusses the challenge and perspective of targeted drugs and immunotherapy for glioma to clarify future directions.

The Blood-Brain Barrier: Implications for Experimental Cancer Therapeutics

The blood-brain barrier is critically important for the treatment of both primary and metastatic cancers of the central nervous system (CNS). Clinical outcomes for patients with primary CNS tumors are poor and have not significantly improved in decades. As treatments for patients with extracranial solid tumors improve, the incidence of CNS metastases is on the rise due to suboptimal CNS exposure of otherwise systemically active agents. Despite state-of-the art surgical care and increasingly precise radiation therapy, clinical progress is limited by the ability to deliver an effective dose of a therapeutic agent to all cancerous cells. Given the tremendous heterogeneity of CNS cancers, both across cancer subtypes and within a single tumor, and the range of diverse therapies under investigation, a nuanced examination of CNS drug exposure is needed. With a shared goal, common vocabulary, and interdisciplinary collaboration, the field is poised for renewed progress in the treatment of CNS cancers.

Individualized Multimodal Immunotherapy for Adults with IDH1 Wild-Type GBM: A Single Institute Experience

Synergistic activity between maintenance temozolomide (TMZm) and individualized multimodal immunotherapy (IMI) during/after first-line treatment has been suggested to improve the overall survival (OS) of adults with IDH1 wild-type MGMT promoter-unmethylated (unmeth) GBM. We expand the data and include the OS of MGMT promoter-methylated (meth) adults with GBM. Unmeth (10 f, 18 m) and meth (12 f, 10 m) patients treated between 27 May 2015 and 1 January 2022 were analyzed retrospectively. There were no differences in age (median: 48 y) or Karnofsky performance index (median: 80). The IMI consisted of 5-day immunogenic cell death (ICD) therapies during TMZm: Newcastle disease virus (NDV) bolus injections and sessions of modulated electrohyperthermia (mEHT); subsequent active specific immunotherapy: dendritic cell (DC) vaccines plus modulatory immunotherapy; and maintenance ICD therapy. There were no differences in the number of vaccines (median: 2), total number of DCs (median: 25.6 × 10⁶), number of NDV injections (median: 31), and number of mEHT sessions (median: 28) between both groups. The median OS of 28 unmeth patients was 22 m (2y-OS: 39%), confirming previous results. OS of 22 meth patients was significantly better (p = 0.0414) with 38 m (2y-OS: 81%). There were no major treatment-related adverse reactions. The addition of IMI during/after standard of care should be prospectively explored.

Gene Therapy for High Grade Glioma: The Clinical Experience

INTRODUCTION

High-grade gliomas (HGG) are the most common malignant primary brain tumors in adults, with a median survival of ~18 months. The standard of care (SOC) is maximal safe surgical resection, and radiation therapy with concurrent and adjuvant temozolomide. This protocol remains unchanged since 2005, even though HGG median survival has marginally improved.

AREAS COVERED

Gene therapy was developed as a promising approach to treat HGG. Here, we review completed and ongoing clinical trials employing viral and non-viral vectors for adult and pediatric HGG, as well as the key supporting preclinical data.

EXPERT OPINION

These therapies have proven safe, and pre- and post-treatment tissue analyses demonstrated tumor cell lysis, increased immune cell infiltration, and increased systemic immune function. Although viral therapy in clinical trials has not yet significantly extended the survival of HGG, promising strategies are being tested. Oncolytic HSV vectors have shown promising results for both adult and pediatric HGG. A recently published study demonstrated that HG47Δ improved survival in recurrent HGG. Likewise, PVSRIPO has shown survival improvement compared to historical controls. It is likely that further analysis of these trials will stimulate the development of new administration protocols, and new therapeutic combinations that will improve HGG prognosis.

Prognosis and clinical features analysis of EMT-related signature and tumor Immune microenvironment in glioma

Background

As the most common primary malignant intracranial tumor, glioblastoma has a poor prognosis with limited treatment options. It has a high propensity for recurrence, invasion, and poor immune prognosis due to the complex tumor microenvironment.

Methods

Six groups of samples from four datasets were included in this study. We used consensus ClusterPlus to establish two subgroups by the EMT-related gene. The difference in clinicopathological features, genomic characteristics, immune infiltration, treatment response and prognoses were evaluated by multiple algorithms. By using LASSO regression, multi-factor Cox analysis, stepAIC method, a prognostic risk model was constructed based on the final screened genes.

Results

The consensusClusterPlus analyses revealed two subtypes of glioblastoma (C1 and C2), which were characterized by different EMT-related gene expression patterns. C2 subtype with the worse prognosis had the more malignant clinical and pathology manifestations, higher Immune infiltration and tumor-associated molecular pathways scores, and poorer response to treatment. Additionally, our EMT-related genes risk prediction model can provide valuable support for clinical evaluations of glioma.

Conclusions

The assessment system and prediction model displayed good performance in independent prognostic risk assessment and individual patient treatment response prediction. This can help with clinical treatment decisions and the development of effective treatments.

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.

Association of Autologous Tumor Lysate-Loaded Dendritic Cell Vaccination With Extension of Survival Among Patients With Newly Diagnosed and Recurrent Glioblastoma: A Phase 3 Prospective Externally Controlled Cohort Trial

Importance

Glioblastoma is the most lethal primary brain cancer. Clinical outcomes for glioblastoma remain poor, and new treatments are needed.

Objective

To investigate whether adding autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) to standard of care (SOC) extends survival among patients with glioblastoma.

Design, Setting, and Participants

This phase 3, prospective, externally controlled nonrandomized trial compared overall survival (OS) in patients with newly diagnosed glioblastoma (nGBM) and recurrent glioblastoma (rGBM) treated with DCVax-L plus SOC vs contemporaneous matched external control patients treated with SOC. This international, multicenter trial was conducted at 94 sites in 4 countries from August 2007 to November 2015. Data analysis was conducted from October 2020 to September 2021.

Interventions

The active treatment was DCVax-L plus SOC temozolomide. The nGBM external control patients received SOC temozolomide and placebo; the rGBM external controls received approved rGBM therapies.

Main Outcomes and Measures

The primary and secondary end points compared overall survival (OS) in nGBM and rGBM, respectively, with contemporaneous matched external control populations from the control groups of other formal randomized clinical trials.

Results

A total of 331 patients were enrolled in the trial, with 232 randomized to the DCVax-L group and 99 to the placebo group. Median OS (mOS) for the 232 patients with nGBM receiving DCVax-L was 19.3 (95% CI, 17.5-21.3) months from randomization (22.4 months from surgery) vs 16.5 (95% CI, 16.0-17.5) months from randomization in control patients (HR = 0.80; 98% CI, 0.00-0.94; P = .002). Survival at 48 months from randomization was 15.7% vs 9.9%, and at 60 months, it was 13.0% vs 5.7%. For 64 patients with rGBM receiving DCVax-L, mOS was 13.2 (95% CI, 9.7-16.8) months from relapse vs 7.8 (95% CI, 7.2-8.2) months among control patients (HR, 0.58; 98% CI, 0.00-0.76; P < .001). Survival at 24 and 30 months after recurrence was 20.7% vs 9.6% and 11.1% vs 5.1%, respectively. Survival was improved in patients with nGBM with methylated MGMT receiving DCVax-L compared with external control patients (HR, 0.74; 98% CI, 0.55-1.00; P = .03).

Conclusions and Relevance

In this study, adding DCVax-L to SOC resulted in clinically meaningful and statistically significant extension of survival for patients with both nGBM and rGBM compared with contemporaneous, matched external controls who received SOC alone.

Trial Registration

ClinicalTrials.gov Identifier: NCT00045968.

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.

Evaluation of the efficacy and safety of TAS0313 in adults with recurrent glioblastoma

Background

TAS0313 is a multi-epitope long peptide vaccine targeting several cancer-associated antigens highly expressed in multiple cancer types, including glioblastoma (GBM). This cohort of a Phase 2 part evaluated the efficacy and safety of TAS0313 in patients with GBM.

Methods

TAS0313 (27 mg) was administered subcutaneously on Days 1, 8 and 15 of Cycles 1 and 2, and Day 1 of subsequent cycles in 21-day cycles. The primary endpoint was the objective response rate (ORR). The secondary endpoints were the disease control rate, progression-free survival (PFS) and 6- and 12-month progression-free survival rates (PFR) and safety. Immunological response was assessed as an exploratory endpoint.

Results

The best overall response was partial response in 1 patient, and the ORR (95% CI) was 11.1% (0.3–48.2%) in the per-protocol set (n = 9). A further 3 patients achieved stable disease, for a disease control rate (95% CI) of 44.4% (13.7–78.8%). Median (95% CI) PFS was 1.7 (1.3–NE) months and 6- and 12-month PFRs (95% CI) were 22.2% (3.4–51.3%) each. Common (≥ 20% incidence) treatment-related adverse events (AEs) were injection site reactions (n = 8, 80.0%), followed by pyrexia (n = 7, 70.0%), and malaise, injection site erythema and injection site pruritus (n = 2, 20.0% each). There were no grade 4 or 5 treatment-related AEs. No deaths occurred during the study. In some patients, TAS0313 treatment was confirmed to increase cytotoxic T lymphocyte and immunoglobulin G levels compared with baseline.

Conclusion

TAS0313, a multi-epitope long peptide vaccine, demonstrated promising efficacy and acceptable safety in patients with recurrent GBM.

Clinical trial registration

JapicCTI-183824 (Date of registration: Jan 11, 2018)

Impact of molecular and clinical variables on survival outcome with immunotherapy for glioblastoma patients: A systematic review and meta-analysis

BACKGROUND

Given that only a subset of patients with glioblastoma multiforme (GBM) responds to immuno-oncology, this study aimed to assess the impact of multiple factors on GBM immunotherapy prognosis and investigate the potential predictors.

METHODS

A quantitative meta-analysis was conducted using the random-effects model. Several potential factors were also reviewed qualitatively.

RESULTS

A total of 39 clinical trials were included after screening 1317 papers. Patients with O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation [hazard ratio (HR) for overall survival (OS) = 2.30, p < 0.0001; HR for progression-free survival (PFS) = 2.10, p < 0.0001], gross total resection (HR for OS = 0.70, p = 0.02; HR for PFS = 0.56, p = 0.004), and no baseline steroid use (HR for OS = 0.52, p = 0.0002; HR for PFS = 0.61, p = 0.02) had a relatively significant favorable OS and PFS following immunotherapy. Patients with a Karnofsky Performance Status score < 80 (HR = 1.73, p = 0.0007) and undergoing two prior relapses (HR = 2.08, p = 0.003) were associated with worse OS. Age, gender, tumor programmed death-ligand 1 expression, and history of chemotherapy were not associated with survival outcomes. Notably, immunotherapy significantly improved the OS among patients undergoing two prior recurrences (HR = 0.40, p = 0.008) but not among patients in any other subgroups, as opposed to non-immunotherapy.

CONCLUSION

Several factors were associated with prognostic outcomes of GBM patients receiving immunotherapy; multiple recurrences might be a candidate predictor. More marker-driven prospective studies are warranted.

Leveraging the neurosurgical operating room for therapeutic development in NeuroOncology

Glioblastoma (GBM) remains a disease with a dismal prognosis. For all the hope and promise immunotherapies and molecular targeted therapies have shown for systemic malignancies, these treatments have failed to show any promise in GBM. In this context, the paradigm of investigation of therapeutics for this disease itself must be examined and modifications considered. The unique challenge of the presence of blood-brain and blood-tumor barriers (BBB/BTB) raises questions about both the true levels of systemic drug delivery to the affected tissues. Window-of-opportunity (WoO) trials in neuro-oncology allow for proof-of-concept at the start of a classic phase I-II-III clinical trial progression. For therapeutics that do not have the ability to cross the BBB/BTB, direct delivery into tumor and/or tumor-infiltrated brain in the setting of a surgical procedure can provide a novel route of therapeutic access. These approaches permit neurosurgeons to play a greater role in therapeutic development for brain tumors.

Comparative efficacy and safety of therapeutics for elderly glioblastoma patients: A Bayesian network analysis

Optimal management strategies for elderly glioblastoma (GBM) patients remain elusive. Overall survival (OS) and progression-free survival (PFS) in elderly newly diagnosed GBM (ndGBM) patients were analyzed with random-effects Bayesian network meta-analysis with the estimated hazard ratio (HR) with a 95% confidence interval (95% CrI). In addition, OS, PFS and adverse event (AE) data on ndGBM and recurrent GBM (rGBM) were assessed. Seventeen eligible trials with 12 on ndGBM and 5 on rGBM were identified. For the improvements it induced in the OS of elderly ndGBM patients, tumor treating field (TTF) + temozolomide (TMZ) (HR: 0.11, 95% CrI: 0.02-0.67 vs. supportive care (SPC)) ranked first, followed by TMZ + hyperfractionated radiotherapy (HFRT) (HR: 0.17, 95% CrI: 0.03-0.95 vs. SPC). For the improvements it induced in the PFS of elderly ndGBM patients, bevacizumab (BEV) + HFRT ranked first, followed by TMZ + HFRT. TMZ was observed to be more effective in O6-methylguanine-DNA-methyltransferase (MGMT) promoter-methylated ndGBM patients than HFRT and standard radiotherapy (STRT). For elderly rGBM patients, the treatments included were comparable. The rates of other neurological symptoms (16.1%) and lymphocytopenia (10.4%) were higher in ndGBM patients; lymphocytopenia (10.3%) and infection (8.1%) were higher in rGBM patients among the ≥ 3 grade AEs. TMZ-related AEs should be further considered. In conclusion, TTF + adjuvant TMZ and TMZ + HFRT are most likely to be recommended for elderly ndGBM patients. No best treatment for rGBM in elderly patients is illustrated. TMZ is identified to be more effective in elderly ndGBM patients with methylated MGMT status; however, AEs associated with TMZ-related therapy should be well considered and managed.

Immune responses of patients without cancer recurrence after a cancer vaccine over a long term

The present study aimed to clarify the humoral and cellular immune responses of patients with cancer who experienced no recurrence over a long term after receiving a cancer vaccine. The immune kinetics were investigated in response to a personalized peptide vaccination (PPV) among 44 Japanese patients without an active tumor at entry to the vaccination: Lung adenocarcinoma (n=11); colon (n=18); and breast cancer (n=15) (9, 10, 12, 8 and 5 patients with stage I, II, III and IV recurrences, respectively). The patients' immunoglobulin G (IgG) and cytotoxic T lymphocyte (CTL) activities were measured using a multiplexed Luminex assay and an interferon-γ release assay, respectively. There were no severe adverse events related to the PPV other than a grade III injection site reaction. A potent boost in IgG or CTL at the end of the 1st vaccination cycle was observed in 77% of the patients (n=84). The IgG levels were sustained throughout the follow-up period, whereas the CTL levels declined and were transient. A total of 37 of the 44 patients (84%) had no recurrence, with a median follow-up of 67.6 months (interquartile range, 45.6-82.8 months). Overall, the PPV induced long-term humoral immunity with transient cellular immunity in the majority of patients with cancer without an active tumor at their entry to the PPV.

Congress of Neurological Surgeons systematic review and evidence-based guidelines update on the role of targeted therapies and immunotherapies in the management of progressive glioblastoma

The following questions and recommendations are pertinent to the following: TARGET POPULATION: These recommendations apply to adults with progressive GBM who have undergone standard primary treatment with surgery and/or chemoradiation. QUESTION 1: In adults with progressive glioblastoma is the use of bevacizumab as monotherapy superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

Level III: Treatment with bevacizumab is suggested in the treatment of progressive GBM, as it provides improved disease control compared to historical controls as measured by best imaging response and progression free survival at 6 months, while not providing evidence for improvement in overall survival. QUESTION 2: In adults with progressive glioblastoma is the use of bevacizumab as combination therapy with cytotoxic agents superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

Level III: There is insufficient evidence to show benefit or harm of bevacizumab in combination with cytotoxic therapies in progressive glioblastoma due to a lack of evidence supporting a clearly defined benefit without significant toxicity. QUESTION 3: In adults with progressive glioblastoma is the use of bevacizumab as a combination therapy with targeted agents superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question. QUESTION 4: In adults with progressive glioblastoma is the use of targeted agents as monotherapy superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question. QUESTION 5: In adults with progressive glioblastoma is the use of targeted agents in combination with cytotoxic therapies superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question. QUESTION 6: In adults with progressive glioblastoma is the use of immunotherapy monotherapy superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question. QUESTION 7: In adults with progressive glioblastoma is the use of immunotherapy in combination with targeted agents superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question. QUESTION 8: In adults with progressive glioblastoma is the use of immunotherapy in combination with bevacizumab superior to standard salvage cytotoxic chemotherapy as measured by progression free survival and overall survival?

RECOMMENDATION

There is insufficient evidence to support a recommendation regarding this question.

Skull modulated strategies to intensify tumor treating fields on brain tumor: a finite element study

Tumor treating fields (TTFields) are a breakthrough in treating glioblastoma (GBM), whereas the intensity cannot be further enhanced, due to the limitation of scalp lesions. Skull remodeling (SR) surgery can elevate the treatment dose of TTFields in the intracranial foci. This study was aimed at exploring the characteristics of the skull modulated strategies toward TTFields augmentation. The simplified multiple-tissue-layer model (MTL) and realistic head (RH) model were reconstructed through finite element methods (FEM), to simulate the remodeling of the skull, which included skull drilling, thinning, and cranioplasty with PEEK, titanium, cerebrospinal fluid (CSF), connective tissue and autologous bone. Skull thinning could enhance the intensity of TTFields in the brain tumor, with a 10% of increase in average peritumoral intensity (API) by every 1 cm decrease in skull thickness. Cranioplasty with titanium accompanied the most enhancement of TTFields in the MTL model, but CSF was superior in TTFields enhancement when simulated in the RH model. Besides, API increased nonlinearly with the expansion of drilled burr holes. In comparison with the single drill replaced by titanium, nine burr holes could reach 96.98% of enhancement in API, but it could only reach 63.08% of enhancement under craniectomy of nine times skull defect area. Skull thinning and drilling could enhance API, which was correlated with the number and area of skull drilling. Cranioplasty with highly conductive material could also augment API, but might not provide clinical benefits as expected.

Glioblastoma Embryonic-like Stem Cells Exhibit Immune-Evasive Phenotype

Simple Summary

Most glioblastoma (GBM) patients relapse after an initial response to treatment. These aggressive traits are often associated with the presence of glioma stem cells (GSCs) within the tumor bulk, which are thought to participate in GBM therapy resistance. Given GBM cellular heterogeneity, we hypothesized that GSCs might also display cellular hierarchies associated with different degrees of stemness. Based on single-cell RNAseq data from GBM patients, we identified a subpopulation of GSCs, named core-GSCs (c-GSCs), with a similar profile to embryonic stem cells and downregulation of immune-associated pathways. In addition, we developed an in vitro induced c-GSC (ic-GSC) model resembling their tumor counterpart. The characterization of immune-privileged c-GSCs provides a valuable resource to study immune evasion mechanisms in GBM and to identify potential unexplored targets to improve immunotherapy treatments.

Abstract

Background: Glioma stem cells (GSCs) have self-renewal and tumor-initiating capacities involved in drug resistance and immune evasion mechanisms in glioblastoma (GBM). Methods: Core-GSCs (c-GSCs) were identified by selecting cells co-expressing high levels of embryonic stem cell (ESC) markers from a single-cell RNA-seq patient-derived GBM dataset (n = 28). Induced c-GSCs (ic-GSCs) were generated by reprogramming GBM-derived cells (GBM-DCs) using induced pluripotent stem cell (iPSC) technology. The characterization of ic-GSCs and GBM-DCs was conducted by immunostaining, transcriptomic, and DNA methylation (DNAm) analysis. Results: We identified a GSC population (4.22% ± 0.59) exhibiting concurrent high expression of ESC markers and downregulation of immune-associated pathways, named c-GSCs. In vitro ic-GSCs presented high expression of ESC markers and downregulation of antigen presentation HLA proteins. Transcriptomic analysis revealed a strong agreement of enriched biological pathways between tumor c-GSCs and in vitro ic-GSCs (κ = 0.71). Integration of our epigenomic profiling with 833 functional ENCODE epigenetic maps identifies increased DNA methylation on HLA genes’ regulatory regions associated with polycomb repressive marks in a stem-like phenotype. Conclusions: This study unravels glioblastoma immune-evasive mechanisms involving a c-GSC population. In addition, it provides a cellular model with paired gene expression, and DNA methylation maps to explore potential therapeutic complements for GBM immunotherapy.

Immunotherapy of glioblastoma: recent advances and future prospects

Glioblastoma (GBM) stands out as the most common, aggressive form of primary malignant brain tumor conferring a devastatingly poor prognosis. Despite aggressive standard-of-care in surgical resection and chemoradiation with temozolomide, the median overall survival of patients still remains no longer than 15 months, due to significant tumor heterogeneity, immunosuppression induced by the tumor immune microenvironment and low mutational burden. Advances in immunotherapeutic approaches have revolutionized the treatment of various cancer types and become conceptually attractive for glioblastoma. In this review, we provide an overview of the basic knowledge underlying immune targeting and promising immunotherapeutic strategies including CAR T cells, oncolytic viruses, cancer vaccines, and checkpoint blockade inhibitors that have been recently investigated in glioblastoma. Current clinical trials and previous clinical trial findings are discussed, shedding light on novel strategies to overcome various limitations and challenges.

Active Immunotherapy for Glioblastoma Treatment: A Systematic Review and Meta-Analysis

INTRODUCTION

Glioblastoma multiforme (GBM) makes 60-70% of gliomas and 15% of primary brain tumors. Despite the availability of standard multimodal therapy, 2 years, 3 years, and 5 years survival rate of GBM are still low. Active immunotherapy is a relatively new treatment option for GBM that seems promising.

METHODS

An electronic database search on PubMed, Cochrane, Scopus, and clinicaltrials.gov was performed to include all relevant studies. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Reported parameters are OS, PFS, AEs, post treatment KPS, and 2 year mortality.

RESULTS

Active immunotherapy provided better OS (HR = .85; 95% CI = .71-1.01; P = .06) and PFS (HS = .83; 95% CI= .66 - 1.03; P = .11) side albeit not statistically significant. Active immunotherapy reduces the risk of 2 year mortality as much as 2.5% compared to control group (NNT and RRR was 56.7078 and 0,0258, respectively).

CONCLUSION

Active immunotherapy might be beneficial in terms of survival rate in patients with GBM although not statistically significant. It could be a treatment option for GBM in the future.

Glioblastoma Clinical Trials: Current Landscape and Opportunities for Improvement

Therapeutic advances for glioblastoma have been minimal over the past 2 decades. In light of the multitude of recent phase III trials that have failed to meet their primary endpoints following promising preclinical and early-phase programs, a Society for Neuro-Oncology Think Tank was held in November 2020 to prioritize areas for improvement in the conduct of glioblastoma clinical trials. Here, we review the literature, identify challenges related to clinical trial eligibility criteria and trial design in glioblastoma, and provide recommendations from the Think Tank. In addition, we provide a data-driven context with which to frame this discussion by analyzing key study design features of adult glioblastoma clinical trials listed on ClinicalTrials.gov as "recruiting" or "not yet recruiting" as of February 2021.

Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline

Purpose

To provide guidance to clinicians regarding therapy for diffuse astrocytic and oligodendroglial tumors in adults.

Methods

ASCO and the Society for Neuro-Oncology convened an Expert Panel and conducted a systematic review of the literature.

Results

Fifty-nine randomized trials focusing on therapeutic management were identified.

Recommendations

Adults with newly diagnosed oligodendroglioma, isocitrate dehydrogenase (IDH)–mutant, 1p19q codeleted CNS WHO grade 2 and 3 should be offered radiation therapy (RT) and procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ) is a reasonable alternative for patients who may not tolerate PCV, but no high-level evidence supports upfront TMZ in this setting. People with newly diagnosed astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 2 should be offered RT with adjuvant chemotherapy (TMZ or PCV). People with astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 should be offered RT and adjuvant TMZ. People with astrocytoma, IDH-mutant, CNS WHO grade 4 may follow recommendations for either astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 or glioblastoma, IDH-wildtype, CNS WHO grade 4. Concurrent TMZ and RT should be offered to patients with newly diagnosed glioblastoma, IDH-wildtype, CNS WHO grade 4 followed by 6 months of adjuvant TMZ. Alternating electric field therapy, approved by the US Food and Drug Administration, should be considered for these patients. Bevacizumab is not recommended. In situations in which the benefits of 6-week RT plus TMZ may not outweigh the harms, hypofractionated RT plus TMZ is reasonable. In patients age ≥ 60 to ≥ 70 years, with poor performance status or for whom toxicity or prognosis are concerns, best supportive care alone, RT alone (for MGMTpromoter unmethylated tumors), or TMZ alone (for MGMT promoter methylated tumors) are reasonable treatment options. Additional information is available at www.asco.org/neurooncology-guidelines.

Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline

PURPOSE

To provide guidance to clinicians regarding therapy for diffuse astrocytic and oligodendroglial tumors in adults.

METHODS

ASCO and the Society for Neuro-Oncology convened an Expert Panel and conducted a systematic review of the literature.

RESULTS

Fifty-nine randomized trials focusing on therapeutic management were identified.

RECOMMENDATIONS

Adults with newly diagnosed oligodendroglioma, isocitrate dehydrogenase (IDH)-mutant, 1p19q codeleted CNS WHO grade 2 and 3 should be offered radiation therapy (RT) and procarbazine, lomustine, and vincristine (PCV). Temozolomide (TMZ) is a reasonable alternative for patients who may not tolerate PCV, but no high-level evidence supports upfront TMZ in this setting. People with newly diagnosed astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 2 should be offered RT with adjuvant chemotherapy (TMZ or PCV). People with astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 should be offered RT and adjuvant TMZ. People with astrocytoma, IDH-mutant, CNS WHO grade 4 may follow recommendations for either astrocytoma, IDH-mutant, 1p19q non-codeleted CNS WHO grade 3 or glioblastoma, IDH-wildtype, CNS WHO grade 4. Concurrent TMZ and RT should be offered to patients with newly diagnosed glioblastoma, IDH-wildtype, CNS WHO grade 4 followed by 6 months of adjuvant TMZ. Alternating electric field therapy, approved by the US Food and Drug Administration, should be considered for these patients. Bevacizumab is not recommended. In situations in which the benefits of 6-week RT plus TMZ may not outweigh the harms, hypofractionated RT plus TMZ is reasonable. In patients age ≥ 60 to ≥ 70 years, with poor performance status or for whom toxicity or prognosis are concerns, best supportive care alone, RT alone (for MGMT promoter unmethylated tumors), or TMZ alone (for MGMT promoter methylated tumors) are reasonable treatment options. Additional information is available at www.asco.org/neurooncology-guidelines.

The current landscape of systemic therapy for recurrent glioblastoma: A systematic review of randomized-controlled trials

AIM

Conduct a systematic review of the effectiveness of systemic therapies for adult recurrent glioblastoma (rGBM).

METHODS

We electronically searched for randomized controlled trials from three major databases and four conferences from 2009-Dec 2020. Two independent reviewers conducted screening, data extraction, and quality assessment.

RESULTS

48 randomized trials were identified. Outcome reporting was inconsistent: overall survival (OS) in 46 studies, progression free survival in 37 studies, 6-month PFS in 30 studies, objective response rate in 28 studies, and 6-month OS in 7 studies. Network meta-analysis was not feasible due to heterogeneity in outcome reporting and single-study linkages. Most studies compared lomustine (8 studies), bevacizumab (18), or temozolomide (8) with other treatments. The median OS across all studies ranged from 3 to 17.6 months.

CONCLUSIONS

Based on level one evidence, there is no superior systemic regimen for rGBM. rGBM is a heterogeneous population with no single regimen demonstrating OS benefit. Registration number: CRD42020148512.

Efficacy and Safety of Actively Personalized Neoantigen Vaccination in the Management of Newly Diagnosed Glioblastoma: A Systematic Review

Purpose

Glioblastoma (GBM) shows frequent relapse and is highly resistant to treatment; therefore, it is considered fatal. Various vaccination protocols that have been tested in patients with GBM, which is the most common and aggressive primary brain tumor, have indicated safety and efficacy, to some extent, when used alone or in combination with standard of care. Recently, neoantigen-based personalized vaccines have shown tremendous immunogenicity and safety in GBM. We aimed to systematically review the medical literature for clinical trials to evaluate the efficacy and safety of neoantigen-based personalized vaccines for newly diagnosed GBM.

Methods

We conducted a literature search for clinical trials on PubMed, Cochrane Library, China National Knowledge Infrastructure, and ClinicalTrials.gov until March 20, 2021. The primary outcomes of interest were immunogenicity and safety of the therapy. Efficacy outcomes, such as progression-free survival and overall survival, were secondary outcomes of interest.

Results

Two clinical trials involving 24 patients were included in this review. High immunogenicity was observed in both studies. The GAPVAC-101 trial reported 50% APVAC1-induced and 84.7% APVAC2-induced immunogenicity with CD8+ and CD4+ T cell responses in 92% (12/13) and 80% (8/10) immune responders, respectively. Two out of five patients showed CD4+ and CD8+ T cell responses in the study by Keskin et al. Dexamethasone use had limited immunogenicity in a trial by Keskin et al (6/8). No serious treatment-related adverse events were reported.

Conclusion

Actively personalized vaccines aimed at unmutated peptides and neoantigens for patients with GBM are safe and highly immunogenic, particularly when administered in combination. Larger studies are warranted to investigate the role.

Immunopeptidomics-Guided Warehouse Design for Peptide-Based Immunotherapy in Chronic Lymphocytic Leukemia

Antigen-specific immunotherapies, in particular peptide vaccines, depend on the recognition of naturally presented antigens derived from mutated and unmutated gene products on human leukocyte antigens, and represent a promising low-side-effect concept for cancer treatment. So far, the broad application of peptide vaccines in cancer patients is hampered by challenges of time- and cost-intensive personalized vaccine design, and the lack of neoepitopes from tumor-specific mutations, especially in low-mutational burden malignancies. In this study, we developed an immunopeptidome-guided workflow for the design of tumor-associated off-the-shelf peptide warehouses for broadly applicable personalized therapeutics. Comparative mass spectrometry-based immunopeptidome analyses of primary chronic lymphocytic leukemia (CLL) samples, as representative example of low-mutational burden tumor entities, and a dataset of benign tissue samples enabled the identification of high-frequent non-mutated CLL-associated antigens. These antigens were further shown to be recognized by pre-existing and de novo induced T cells in CLL patients and healthy volunteers, and were evaluated as pre-manufactured warehouse for the construction of personalized multi-peptide vaccines in a first clinical trial for CLL (NCT04688385). This workflow for the design of peptide warehouses is easily transferable to other tumor entities and can provide the foundation for the development of broad personalized T cell-based immunotherapy approaches.

Treatment options for progression or recurrence of glioblastoma: a network meta-analysis

BACKGROUND

Glioblastoma (GBM) is a highly malignant brain tumour that almost inevitably progresses or recurs after first line standard of care. There is no consensus regarding the best treatment/s to offer people upon disease progression or recurrence. For the purposes of this review, progression and recurrence are considered as one entity.

OBJECTIVES

To evaluate the effectiveness of further treatment/s for first and subsequent progression or recurrence of glioblastoma (GBM) among people who have received the standard of care (Stupp protocol) for primary treatment of the disease; and to prepare a brief economic commentary on the available evidence.

SEARCH METHODS

We searched MEDLINE and Embase electronic databases from 2005 to December 2019 and the Cochrane Central Register of Controlled Trials (CENTRAL, in the Cochrane Library; Issue 12, 2019). Economic searches included the National Health Service Economic Evaluation Database (NHS EED) up to 2015 (database closure) and MEDLINE and Embase from 2015 to December 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and comparative non-randomised studies (NRSs) evaluating effectiveness of treatments for progressive/recurrent GBM. Eligible studies included people with progressive or recurrent GBM who had received first line radiotherapy with concomitant and adjuvant temozolomide (TMZ).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data to a pre-designed data extraction form. We conducted network meta-analyses (NMA) and ranked treatments according to effectiveness for each outcome using the random-effects model and Stata software (version 15). We rated the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 42 studies: these comprised 34 randomised controlled trials (RCTs) and 8 non-randomised studies (NRSs) involving 5236 participants. We judged most RCTs to be at a low risk of bias and NRSs at high risk of bias. Interventions included chemotherapy, re-operation, re-irradiation and novel therapies either used alone or in combination. For first recurrence, we included 11 interventions in the network meta-analysis (NMA) for overall survival (OS), and eight in the NMA for progression-free survival (PFS). Lomustine (LOM; also known as CCNU) was the most common comparator and was used as the reference treatment. No studies in the NMA evaluated surgery, re-irradiation, PCV (procarbazine, lomustine, vincristine), TMZ re-challenge or best supportive care. We could not perform NMA for second or later recurrence due to insufficient data. Quality-of-life data were sparse. First recurrence (NMA findings) Median OS across included studies in the NMA ranged from 5.5 to 12.6 months and median progression-free survival (PFS) ranged from 1.5 months to 4.2 months. We found no high-certainty evidence that any treatments tested were better than lomustine. These treatments included the following. Bevacizumab plus lomustine: Evidence suggested probably little or no difference in OS between bevacizumab (BEV) combined with lomustine (LOM) and LOM monotherapy (hazard ratio (HR) 0.91, 0.75 to 1.10; moderate-certainty evidence), although BEV + LOM may improve PFS (HR 0.57, 95% confidence interval (CI) 0.44 to 0.74; low-certainty evidence). Bevacizumab monotherapy: Low-certainty evidence suggested there may be little or no difference in OS (HR 1.22, 95% CI 0.84 to 1.76) and PFS (HR 0.90, 95% CI 0.58 to 1.38; low-certainty evidence) between BEV and LOM monotherapies; more evidence on BEV is needed. Regorafenib (REG): REG may improve OS compared with LOM (HR 0.50, 95% CI 0.33 to 0.76; low-certainty evidence). Evidence on PFS was very low certainty and more evidence on REG is needed. Temozolomide (TMZ) plus Depatux-M (ABT414): For OS, low-certainty evidence suggested that TMZ plus ABT414 may be more effective than LOM (HR 0.66, 95% CI 0.47 to 0.92) and may be more effective than BEV (HR 0.54, 95% CI 0.33 to 0.89; low-certainty evidence). This may be due to the TMZ component only and more evidence is needed. Fotemustine (FOM): FOM and LOM may have similar effects on OS (HR 0.89, 95% CI 0.51 to 1.57, low-certainty evidence). Bevacizumab and irinotecan (IRI): Evidence on BEV + irinotecan (IRI) versus LOM for both OS and PFS is very uncertain and there is probably little or no difference between BEV + IRI versus BEV monotherapy (OS: HR 0.95, 95% CI 0.70 to 1.30; moderate-certainty evidence). When treatments were ranked for OS, FOM ranked first, BEV + LOM second, LOM third, BEV + IRI fourth, and BEV fifth. Ranking does not take into account the certainty of the evidence, which also suggests there may be little or no difference between FOM and LOM. Other treatments Three studies evaluated re-operation versus no re-operation, with or without re-irradiation and chemotherapy, and these suggested possible survival advantages with re-operation within the context of being able to select suitable candidates for re-operation. A cannabinoid treatment in the early stages of evaluation, in combination with TMZ, merits further evaluation. Second or later recurrence Limited evidence from three heterogeneous studies suggested that radiotherapy with or without BEV may have a beneficial effect on survival but more evidence is needed. Evidence was insufficient to draw conclusions about the best radiotherapy dosage. Other evidence suggested that there may be little difference in survival with tumour-treating fields compared with physician's best choice of treatment. We found no reliable evidence on best supportive care. Severe adverse events (SAEs) The BEV+LOM combination was associated with significantly greater risk of SAEs than LOM monotherapy (RR 2.51, 95% CI 1.72 to 3.66, high-certainty evidence), and ranked joint worst with cediranib + LOM (RR 2.51, 95% CI 1.29 to 4.90; high-certainty evidence). LOM ranked best and REG ranked second best. Adding novel treatments to BEV was generally associated with a higher risk of severe adverse events compared with BEV alone.

AUTHORS' CONCLUSIONS

For treatment of first recurrence of GBM, among people previously treated with surgery and standard chemoradiotherapy, the combination treatments evaluated did not improve overall survival compared with LOM monotherapy and were often associated with a higher risk of severe adverse events. Limited evidence suggested that re-operation with or without re-irradiation and chemotherapy may be suitable for selected candidates. Evidence on second recurrence is sparse. Re-irradiation with or without bevacizumab may be of value in selected individuals, but more evidence is needed.

Immunotherapy and radiation for high-grade glioma: a narrative review

Glioblastoma and other high-grade gliomas (HGGs) are the most common and deadly primary brain tumors. Due to recent advances in immunotherapy and improved clinical outcomes in other disease sites, the study of immunotherapy in HGG has increased significantly. Herein, we summarize and evaluate existing evidence and ongoing clinical trials investigating the use of immunotherapy in the treatment of HGG, including therapeutic vaccination, immune checkpoint inhibition, adoptive lymphocyte transfer, and combinatorial approaches utilizing radiation and multiple modalities of immunotherapy. Special attention is given to the mechanisms by which radiation may improve immunogenicity in HGG, why this motivates the study of radiation in combination with immunotherapy, and how to determine optimal dosing and scheduling of radiation. Though larger randomized controlled trials have not consistently shown improvements in clinical outcomes, this area of research is still in its early stages and a number of important lessons can be taken away from the studies that have been completed to date. Many studies found a subset of patients who experienced durable responses, and analysis of their immune cells and tumor cells can be used to identify biomarkers that predict therapeutic response, as well as additional glioma-specific targets that can enhance therapeutic efficacy in a challenging tumor type.