CAR T-cell therapy for glioblastoma: ready for the next round of clinical testing?

Glioblastoma Vaccines as Promising Immune-Therapeutics: Challenges and Current Status

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor. Standard treatments including surgical resection, radiotherapy, and chemotherapy, have failed to significantly improve the prognosis of glioblastoma patients. Currently, immunotherapeutic approaches based on vaccines, chimeric antigen-receptor T-cells, checkpoint inhibitors, and oncolytic virotherapy are showing promising results in clinical trials. The combination of different immunotherapeutic approaches is proving satisfactory and promising. In view of the challenges of immunotherapy and the resistance of glioblastomas, the treatment of these tumors requires further efforts. In this review, we explore the obstacles that potentially influence the efficacy of the response to immunotherapy and that should be taken into account in clinical trials. This article provides a comprehensive review of vaccine therapy for glioblastoma. In addition, we identify the main biomarkers, including isocitrate dehydrogenase, epidermal growth factor receptor, and telomerase reverse transcriptase, known as potential immunotherapeutic targets in glioblastoma, as well as the current status of clinical trials. This paper also lists proposed solutions to overcome the obstacles facing immunotherapy in glioblastomas.

An updated overview of the application of CAR-T cell therapy in neurological diseases

Genetically modified immune cells, especially CAR-T cells, have captured the attention of scientists over the past 10 years. In the fight against cancer, these cells have a special place. Treatment for hematological cancers, autoimmune disorders, and cancers must include CAR-T cell therapy. Determining the therapeutic targets, side effects, and use of CAR-T cells in neurological disorders, including cancer and neurodegenerative diseases, is the goal of this study. Due to advancements in genetic engineering, CAR-T cells have become crucial in treating some neurological disorders. CAR-T cells have demonstrated a positive role in treating neurological cancers like Glioblastoma and Neuroblastoma due to their ability to cross the blood-brain barrier and use diverse targets. However, CAR-T cell therapy for MS diseases is being researched and could be a potential treatment option. This study aimed to access the most recent studies and scientific articles in the field of CAR-T cells in neurological diseases and/or disorders.

Chimeric Antigen Receptor T Cells in Glioblastoma-Current Concepts and Promising Future

Glioblastoma (GBM) is a highly aggressive primary brain tumor that is largely refractory to treatment and, therefore, invariably relapses. GBM patients have a median overall survival of 15 months and, given this devastating prognosis, there is a high need for therapy improvement. One of the therapeutic approaches currently tested in GBM is chimeric antigen receptor (CAR)-T cell therapy. CAR-T cells are genetically altered T cells that are redirected to eliminate tumor cells in a highly specific manner. There are several challenges to CAR-T cell therapy in solid tumors such as GBM, including restricted trafficking and penetration of tumor tissue, a highly immunosuppressive tumor microenvironment (TME), as well as heterogeneous antigen expression and antigen loss. In addition, CAR-T cells have limitations concerning safety, toxicity, and the manufacturing process. To date, CAR-T cells directed against several target antigens in GBM including interleukin-13 receptor alpha 2 (IL-13Rα2), epidermal growth factor receptor variant III (EGFRvIII), human epidermal growth factor receptor 2 (HER2), and ephrin type-A receptor 2 (EphA2) have been tested in preclinical and clinical studies. These studies demonstrated that CAR-T cell therapy is a feasible option in GBM with at least transient responses and acceptable adverse effects. Further improvements in CAR-T cells regarding their efficacy, flexibility, and safety could render them a promising therapy option in GBM.

GD2 CAR-T cells in combination with Nivolumab exhibit enhanced antitumor efficacy

Glioblastoma (GBM) is a common primary brain tumor with poor clinical prognosis. Although CAR-T therapy has been trialed for treatment of GBM, the outcomes are sub-optimal possibly due to exhaustion of T cells and life-threatening neurotoxicity. To address these issues, a combined therapeutic strategy was tested in the current study using GD2 CAR-T together with Nivolumab - an anti-PD-1 monoclonal antibody. An effector-to-target co-culture system was established to evaluate the short-term and long-term cytotoxicity of CAR-T, as well as to investigate the inhibitory activity and T cell exhaustion associated with the PD-1/PD-L1 signaling pathway. Orthotopic NOD/SCID GBM animal models were generated to evaluate the safety and efficacy of the combined therapeutic strategy at various dosages of GD2 CAR-T with Nivolumab. GD2 CAR-T exhibited significant antigen-specific cytotoxicity in a dose-dependent manner in vitro. The persistence of cytotoxicity of GD2 CAR-T could be enhanced by addition of Nivolumab in the co-culture system. Animal studies suggested that GD2 CAR-T effectively infiltrated into tumor tissue and significantly hampered tumor progression. The optimal therapeutic outcome was obtained via using the medium dosage of CAR-T with Nivolumab, which displayed the highest efficacy in extending the survival up to 60 days. Further investigation of toxicity revealed that high-dosage of GD2 CAR-T could induce tumor apoptosis through p53/caspase-3/PARP signaling pathway. This study suggests that GD2 CAR-T in combination with Nivolumab may offer an improved therapeutic strategy for treatment of GBM.

Absorption rate governs cell transduction in dry macroporous scaffolds

Developing the next generation of cellular therapies will depend on fast, versatile, and efficient cellular reprogramming. Novel biomaterials will play a central role in this process by providing scaffolding and bioactive signals that shape cell fate and function. Previously, our lab reported that dry macroporous alginate scaffolds mediate retroviral transduction of primary T cells with efficiencies that rival the gold-standard clinical spinoculation procedures, which involve centrifugation on Retronectin-coated plates. This scaffold transduction required the scaffolds to be both macroporous and dry. Transduction by dry, macroporous scaffolds, termed "Drydux transduction," provides a fast and inexpensive method for transducing cells for cellular therapy, including for the production of CAR T cells. In this study, we investigate the mechanism of action by which Drydux transduction works through exploring the impact of pore size, stiffness, viral concentration, and absorption speed on transduction efficiency. We report that Drydux scaffolds with macropores ranging from 50-230 μm and with Young's moduli ranging from 25-620 kPa all effectively transduce primary T cells, suggesting that these parameters are not central to the mechanism of action, but also demonstrating that Drydux scaffolds can be tuned without losing functionality. Increasing viral concentrations led to significantly higher transduction efficiencies, demonstrating that increased cell-virus interaction is necessary for optimal transduction. Finally, we discovered that the rate with which the cell-virus solution is absorbed into the scaffold is closely correlated to viral transduction efficiency, with faster absorption producing significantly higher transduction. A computational model of liquid flow through porous media validates this finding by showing that increased fluid flow substantially increases collisions between virus particles and cells in a porous scaffold. Taken together, we conclude that the rate of liquid flow through the scaffolds, rather than pore size or stiffness, serves as a central regulator for efficient Drydux transduction.

Continuous EEG monitoring detects nonconvulsive seizure and Ictal-Interictal Continuum abnormalities in moderate to severe ICANS following systemic CAR-T therapy

Background and Purpose

Immune Cell Effector Associated Neurotoxicity Syndrome (ICANS) is common amongst patients receiving CD19 targeted Chimeric Antigen Receptor T-cell (CAR-T) therapy. The purpose of this study is to characterize the incidence of seizures and ictal-interictal continuum (IIC) abnormalities in patients with ICANS.

Methods

Retrospective review of consecutive patients treated with axicabtagene ciloleucel (axi-cel) for recurrent high-grade systemic lymphoma at Stanford Medical Center between 2/2016-6/2019. Electronic medical records (EMR) were reviewed for clinical features, treatment information, EEG data, CRS (cytokine release syndrome)/ICANS severity, and clinical outcomes.

Results

Fifty-six patients met inclusion criteria. 85.7% of patients developed CRS, and 58.9% developed ICANS. Twenty-eight patients had EEG monitoring, of whom 26 had ICANS. Median duration of EEG monitoring was 30 hours (range .5-126 hours). Four patients (7.1%) had seizures (1 patient had a clinical generalized seizure, 2 patients had clinical and nonconvulsive seizures, and 1 patient had an isolated non-convulsive seizure). Ictal-interictal continuum abnormalities were common, of which generalized periodic discharges (GPDs) with triphasic morphology and GPDs with epileptiform morphology were most frequently seen. Generalized periodic discharges with triphasic wave morphology were found across Grade 2-3 peak ICANS severity, however the majority (86%) of patients with epileptiform GPDs had Grade 3 peak ICANS severity.

Conclusions

Among patients receiving axi-cel, seizure occurred in 7.1% of the total cohort, representing 12% of patients with ICANS. Ictal-interictal continuum abnormalities are also seen in patients with ICANS, most commonly GPDs. 75% of patients with seizures had nonconvulsive seizures supporting the use of continuous video EEG monitoring in this population.

Recent advances in the therapeutic strategies of glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the most common, most formidable, and deadliest malignant types of primary astrocytoma with a poor prognosis. At present, the standard of care includes surgical tumor resection, followed by radiation therapy concomitant with chemotherapy and temozolomide. New developments and significant advances in the treatment of GBM have been achieved in recent decades. However, despite the advances, recurrence is often inevitable, and the survival of patients remains low. Various factors contribute to the difficulty in identifying an effective therapeutic option, among which are tumor complexity, the presence of the blood-brain barrier (BBB), and the presence of GBM cancer stem cells, prompting the need for improving existing treatment approaches and investigating new treatment alternatives for ameliorating the treatment strategies of GBM. In this review, we outline some of the most recent literature on the various available treatment options such as surgery, radiotherapy, cytotoxic chemotherapy, gene therapy, immunotherapy, phototherapy, nanotherapy, and tumor treating fields in the treatment of GBM, and we list some of the potential future directions of GBM. The reviewed studies confirm that GBM is a sophisticated disease with several challenges for scientists to address. Hence, more studies and a multimodal therapeutic approach are crucial to yield an effective cure and prolong the survival of GBM patients.

Immunotherapeutic treatments for spinal and peripheral nerve tumors: a primer

OBJECTIVE

Spinal and peripheral nerve tumors are a heterogeneous group of neoplasms that can be associated with significant morbidity and mortality despite the current standard of care. Immunotherapy is an emerging therapeutic option to improve the prognoses of these tumors. Therefore, the authors sought to present an updated and unifying review on the use of immunotherapy in treating tumors of the spinal cord and peripheral nerves, including a discussion on mechanism of action, drug delivery, current treatment techniques, and preclinical and clinical studies.

METHODS

Current data in the literature regarding immunotherapy were collated and summarized. Targeted tumors included primary and secondary spinal tumors, as well as peripheral nerve tumors.

RESULTS

Four primary modalities of immunotherapy (CAR T cell, monoclonal antibody, viral, and cytokine) have been reported to target spine and peripheral nerve tumors. Of the primary spinal tumors, spinal cord astrocytomas had the most preclinical evidence supporting immunotherapy success with CAR T-cell therapy targeting the H3K27M mutation, whereas spinal schwannomas and ependymomas had the most evidence reported for monoclonal antibody therapy preclinically. Of the secondary spinal tumors, primary CNS lymphomas demonstrated some clinical response to immunotherapy, whereas multiple myeloma and bone tumor experiences with immunotherapy were largely limited to concept only. Within peripheral nerve tumors, the use of immunotherapy to treat neurofibromas in the setting of syndromes has been suggested in theory, and possible immunotherapeutic targets have been identified in malignant peripheral nerve tumors. To date, there have been 2 clinical trials involving spine tumors and 2 clinical trials involving peripheral nerve tumors that have reported results, all of which are promising but require validation.

CONCLUSIONS

Immunotherapy to treat spinal and peripheral nerve tumors has become an emerging area of research and interest. A large amount of preclinical data supporting the translation of this therapy into practice, aimed at ameliorating the poor prognoses of specific tumors, have been reported. Future clinical studies for translation will focus on the optimal therapy type and administration route to best target these tumors, which often preclude total surgical resection given their proximity to the neural and vascular elements of the spine.

Allogeneic CAR T Cells: An Alternative to Overcome Challenges of CAR T Cell Therapy in Glioblastoma

Chimeric antigen receptor (CAR) T cell therapy has emerged as one of the major breakthroughs in cancer immunotherapy in the last decade. Outstanding results in hematological malignancies and encouraging pre-clinical anti-tumor activity against a wide range of solid tumors have made CAR T cells one of the most promising fields for cancer therapies. CAR T cell therapy is currently being investigated in solid tumors including glioblastoma (GBM), a tumor for which survival has only modestly improved over the past decades. CAR T cells targeting EGFRvIII, Her2, or IL-13Rα2 have been tested in GBM, but the first clinical trials have shown modest results, potentially due to GBM heterogeneity and to the presence of an immunosuppressive microenvironment. Until now, the use of autologous T cells to manufacture CAR products has been the norm, but this approach has several disadvantages regarding production time, cost, manufacturing delay and dependence on functional fitness of patient T cells, often reduced by the disease or previous therapies. Universal “off-the-shelf,” or allogeneic, CAR T cells is an alternative that can potentially overcome these issues, and allow for multiple modifications and CAR combinations to target multiple tumor antigens and avoid tumor escape. Advances in genome editing tools, especially via CRISPR/Cas9, might allow overcoming the two main limitations of allogeneic CAR T cells product, i.e., graft-vs.-host disease and host allorejection. Here, we will discuss how allogeneic CAR T cells could allow for multivalent approaches and alteration of the tumor microenvironment, potentially allowing the development of next generation therapies for the treatment of patients with GBM.

Challenges and Perspectives of Standard Therapy and Drug Development in High-Grade Gliomas

Despite their low incidence rate globally, high-grade gliomas (HGG) remain a fatal primary brain tumor. The recommended therapy often is incapable of resecting the tumor entirely and exclusively targeting the tumor leads to tumor recurrence and dismal prognosis. Additionally, many HGG patients are not well suited for standard therapy and instead, subjected to a palliative approach. HGG tumors are highly infiltrative and the complex tumor microenvironment as well as high tumor heterogeneity often poses the main challenges towards the standard treatment. Therefore, a one-fit-approach may not be suitable for HGG management. Thus, a multimodal approach of standard therapy with immunotherapy, nanomedicine, repurposing of older drugs, use of phytochemicals, and precision medicine may be more advantageous than a single treatment model. This multimodal approach considers the environmental and genetic factors which could affect the patient's response to therapy, thus improving their outcome. This review discusses the current views and advances in potential HGG therapeutic approaches and, aims to bridge the existing knowledge gap that will assist in overcoming challenges in HGG.

Chimeric Antigen Receptor T-Cell Therapy in Glioblastoma: Current and Future

Glioblastoma (GBM) is a highly aggressive glioma with an extremely poor prognosis after conventional treatment. Recent advances in immunotherapy offer hope for these patients with incurable GBM. Our present review aimed to provide an overview of immunotherapy for GBM, especially chimeric antigen receptor T-cell (CAR T) therapy. CAR T-cell immunotherapy, which involves the engineering of T cells to kill tumors by targeting cell surface-specific antigens, has been successful in eliminating B-cell leukemia by targeting CD19. IL-13Rα2, EGFRvIII, and HER2-targeted CAR T cells have shown significant clinical efficacy and safety in phase 1 or 2 clinical trials conducted in patients with GBM; these findings support the need for further studies to examine if this therapy can ultimately benefit this patient group. However, local physical barriers, high tumor heterogeneity, and antigen escape make the use of CAR T therapy, as a treatment for GBM, challenging. The potential directions for improving the efficacy of CAR T in GBM are to combine the existing traditional therapies and the construction of multi-target CAR T cells.

New hints towards a precision medicine strategy for IDH wild-type glioblastoma

Glioblastoma represents the most common primary malignancy of the central nervous system in adults and remains a largely incurable disease. The elucidation of disease subtypes based on mutational profiling, gene expression and DNA methylation has so far failed to translate into improved clinical outcomes. However, new knowledge emerging from the subtyping effort in the IDH-wild-type setting may provide directions for future precision therapies. Here, we review recent learnings in the field, and further consider how tumour microenvironment differences across subtypes may reveal novel contexts of vulnerability. We discuss recent treatment approaches and ongoing trials in the IDH-wild-type glioblastoma setting, and propose an integrated discovery stratagem incorporating multi-omics, single-cell technologies and computational approaches.

Adoptive Cell Therapy: A Novel and Potential Immunotherapy for Glioblastoma

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults with very poor prognosis and few advances in its treatment. Recently, fast-growing cancer immunotherapy provides a glimmer of hope for GBM treatment. Adoptive cell therapy (ACT) aims at infusing immune cells with direct anti-tumor activity, including tumor-infiltrating lymphocyte (TIL) transfer and genetically engineered T cells transfer. For example, complete regressions in patients with melanoma and refractory lymphoma have been shown by using naturally tumor-reactive T cells and genetically engineered T cells expressing the chimeric anti-CD19 receptor, respectively. Recently, the administration of ACT showed therapeutic potentials for GBM treatment as well. In this review, we summarize the success of ACT in the treatment of cancer and provide approaches to overcome some challenges of ACT to allow its adoption for GBM treatment.

Antibodies Against Hypothalamus and Pituitary Gland in Childhood-Onset Brain Tumors and Pituitary Dysfunction

Purpose: To detect the presence of antipituitary (APA) and antihypothalamus antibodies (AHA) in subjects treated for brain cancers, and to evaluate their potential association with pituitary dysfunction. Methods: We evaluated 63 patients with craniopharyngioma, glioma, and germinoma treated with surgery and/or radiotherapy and/or chemotherapy at a median age of 13 years. Forty-one had multiple pituitary hormone deficiencies (MPHD), six had a single pituitary defect. GH was the most common defect (65.1%), followed by AVP (61.9%), TSH (57.1%), ACTH (49.2%), and gonadotropin (38.1%). APA and AHA were evaluated by simple indirect immunofluorescence method indirect immunofluorescence in patients and in 50 healthy controls. Results: Circulating APA and/or AHA were found in 31 subjects (49.2%) and in none of the healthy controls. In particular, 25 subjects out of 31 were APA (80.6%), 26 were AHA (83.90%), and 20 were both APA and AHA (64.5%). Nine patients APA and/or AHA have craniopharyngioma (29%), seven (22.6%) have glioma, and 15 (48.4%) have germinoma. Patients with craniopharyngioma were positive for at least one antibody in 39.1% compared to 33.3% of patients with glioma and to 78.9% of those with germinoma with an analogous distribution for APA and AHA between the three tumors. The presence of APA or AHA and of both APA and AHA was significantly increased in patients with germinoma. The presence of APA (P = 0.001) and their titers (P = 0.001) was significantly associated with the type of tumor in the following order: germinomas, craniopharyngiomas, and gliomas; an analogous distribution was observed for the presence of AHA (P = 0.002) and their titers (P = 0.012). In addition, we found a significant association between radiotherapy and APA (P = 0.03). Conclusions: Brain tumors especially germinoma are associated with the development of hypothalamic-pituitary antibodies and pituitary defects. The correct interpretation of APA/AHA antibodies is essential to avoid a misdiagnosis of an autoimmune infundibulo-neurohypophysitis or pituitary hypophysitis in patients with germinoma.

CAR-Engineered NK Cells for the Treatment of Glioblastoma: Turning Innate Effectors Into Precision Tools for Cancer Immunotherapy

Glioblastoma (GB) is the most common and aggressive primary brain tumor in adults and currently incurable. Despite multimodal treatment regimens, median survival in unselected patient cohorts is <1 year, and recurrence remains almost inevitable. Escape from immune surveillance is thought to contribute to the development and progression of GB. While GB tumors are frequently infiltrated by natural killer (NK) cells, these are actively suppressed by the GB cells and the GB tumor microenvironment. Nevertheless, ex vivo activation with cytokines can restore cytolytic activity of NK cells against GB, indicating that NK cells have potential for adoptive immunotherapy of GB if potent cytotoxicity can be maintained in vivo. NK cells contribute to cancer immune surveillance not only by their direct natural cytotoxicity which is triggered rapidly upon stimulation through germline-encoded cell surface receptors, but also by modulating T-cell mediated antitumor immune responses through maintaining the quality of dendritic cells and enhancing the presentation of tumor antigens. Furthermore, similar to T cells, specific recognition and elimination of cancer cells by NK cells can be markedly enhanced through expression of chimeric antigen receptors (CARs), which provides an opportunity to generate NK-cell therapeutics of defined specificity for cancer immunotherapy. Here, we discuss effects of the GB tumor microenvironment on NK-cell functionality, summarize early treatment attempts with ex vivo activated NK cells, and describe relevant CAR target antigens validated with CAR-T cells. We then outline preclinical approaches that employ CAR-NK cells for GB immunotherapy, and give an overview on the ongoing clinical development of ErbB2 (HER2)-specific CAR-NK cells currently applied in a phase I clinical trial in glioblastoma patients.

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

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