The role of checkpoints in the treatment of GBM

Immunotherapy with autologous dendritic cells in the complex treatment of malignant gliomas - results

ANNOTATION

Malignant gliomas are the most common primary brain tumor. Despite the variety of modern treatments, it is still a fatal disease with an extremely poor prognosis. The use of immunotherapy as a technique for the treatment of malignant tumors has great promise, retraining and exploiting the patient's immune response against tumors.

OBJECTIVE

Evaluation of the effectiveness of dendritic cell vaccine in patients with malignant brain gliomas in the structure of complex treatment in comparison with the control group of patients without immunotherapy in the structure of treatment.

MATERIALS AND METHODS

In a single-center, prospective, cohort study, taking place on the basis of the RNSI named after prof. A.L. Polenov, 91 patients with morphologically established malignant glial tumor (glioblastoma) took part. The main group of 41 patients who, in addition to standard treatment (surgical, radiation and chemotherapy), underwent specific antitumor immunotherapy. 50 patients received only standard treatment, without immunotherapy.

RESULTS

Median survival was 21.7 months in the immunotherapy group (95% CI 4-37 months) and 15.8 months (95% CI 3-22 months) in the non-immunotherapy group (p = 0.002). The median relapse-free period in the group with immunotherapy was 13.8 months (95% CI 1-20 months), and in the group without immunotherapy 7.9 months (95% CI 1-12 months) (p = 0.003).

CONCLUSION

In general, the use of immunotherapy in the structure of complex treatment of patients with malignant gliomas demonstrates a clear positive trend in terms of overall survival and median relapse-free period. But nevertheless, immunotherapy requires further development as a therapeutic tool, study and improvement, which will take into account immunosuppression in malignant gliomas and means of overcoming it, optimization in terms of target antigen selection, cell preparation and integration of dendritic vaccines into other treatment regimens.

Immunotherapy for glioblastoma: the promise of combination strategies

Glioblastoma (GBM) treatment has remained almost unchanged for more than 20 years. The current standard of care involves surgical resection (if possible) followed by concomitant radiotherapy and chemotherapy. In recent years, immunotherapy strategies have revolutionized the treatment of many cancers, increasing the hope for GBM therapy. However, mostly due to the high, multifactorial immunosuppression occurring in the microenvironment, the poor knowledge of the neuroimmune system and the presence of the blood-brain barrier, the efficacy of immunotherapy in GBM is still low. Recently, new strategies for GBM treatments have employed immunotherapy combinations and have provided encouraging results in both preclinical and clinical studies. The lessons learned from clinical trials highlight the importance of tackling different arms of immunity. In this review, we aim to summarize the preclinical evidence regarding combination immunotherapy in terms of immune and survival benefits for GBM management. The outcomes of recent studies assessing the combination of different classes of immunotherapeutic agents (e.g., immune checkpoint blockade and vaccines) will be discussed. Finally, future strategies to ameliorate the efficacy of immunotherapy and facilitate clinical translation will be provided to address the unmet medical needs of GBM.

Higher cytolytic score correlates with an immunosuppressive tumor microenvironment and reduced survival in glioblastoma

Cytolytic score (CYT), calculated from mRNA expression levels of granzyme and perforin, positively correlates with CD8+ T cell infiltration/activity in a variety of cancers. Unlike other cancers, higher CYT has been associated with worse prognosis in glioblastoma (GBM). To address this discrepancy, we sought to investigate the relationship between CYT and immune checkpoint gene score (ICGscore), as well as their correlation with patient survival and tumor immune cell infiltration. Clinical and RNA-sequencing data for patients with newly diagnosed GBM were obtained from The Cancer Genome Atlas. Maximally-selected rank statistics was used to dichotomize subgroups. CIBERSORT was used to estimate abudence of immune cell-types. Spearman correlation was used to characterize the relationship between CYT and ICGscore. Kaplan-Meier curves were generated for survival analysis. Overall, 28/151 patients had high CYT. High CYT was associated with a mesenchymal subtype (p < 0.001) and worse survival (7.45 vs. 12.2 months, p < 0.001). There were no differences in patient demographics, IDH/MGMT mutation status, or treatment. On subgroup analysis, patients with high CYT/ICGscore had significantly increased CD8+ infiltration (p < 0.001), as expected, and worse survival (HR 0.445, p < 0.01). Furthermore, CYT strongly correlated with ICGscore (RS = 0.675, p < 0.001). The high CYT/ICGscore subgroup was associated with greater infiltration of M2 macrophages (p = 0.011) and neutrophils (p = 0.055). Our study highlights a multidimensional immunosuppressive GBM microenvironment in patients with higher CYT and potentially identifies patients with high CYT/ICGscore as a subgroup that may particularly benefit from multi-faceted immunotherapies, given their already elevated tumor CD8+ T cell levels.

Current clinical management of patients with glioblastoma

BACKGROUND

Glioblastoma (GB) is the most aggressive primary brain tumor, historically resistant to treatment, and with overall fatal outcome.

RECENT FINDINGS

Recently, several molecular subgroups and rare genetic alterations have been described in GB. In this review article, we will describe the current clinical management of patients with GB in the United States, discuss selected next-generation molecular-targeted therapies in GB, and present ongoing clinical trials for patients with GB. This review is intended for clinical and preclinical researchers who conduct work on GB and would like to understand more about the current standard of treatment of GB patients, historical perspectives, current challenges, and ongoing and upcoming clinical trials.

CONCLUSIONS

GB is an extremely complex disease, and despite recent progress and advanced therapeutic strategies, the overall patient's prognosis remains dismal. Innovative strategies and integrative ways of approach to disease are urgently needed.

Nivolumab in the Treatment of Recurrent or Refractory Pediatric Brain Tumors: A Single Institutional Experience

Successful use of immune checkpoint inhibitors in a variety of cancers has generated interest in using this approach in pediatric brain tumors. We performed a retrospective review of 10 consecutive children (6 boys, 4 girls; ages, 2 to 17 y), with recurrent or refractory pediatric brain tumors (5 high-grade glioma, 1 low-grade glioma, pineoblastoma, medulloblastoma, ependymoma, and CNS embryonal tumor, NOS) treated at Rady Children's Hospital San Diego from 2015 to 2017 with the immune checkpoint inhibitor nivolumab (3 mg/kg every 2 wk). Eight of 10 patients received prior chemotherapy and 9 radiation therapy. Nine patients had radiographic disease progression (median, 2.5 doses). Median time to progression was 5.5 weeks (1.6 to 24 wk). Three patients (2 with high-grade glioma, 1 with CNS embryonal tumor NOS) showed a partial response to treatment at the primary tumor site and 2 of 3 had progression of metastatic disease. Grade 2 toxicities were observed without dose limiting side effects. Tumor mutation burden (TMB) was low to intermediate (median, 1.3; range, 0 to 6.3). Median survival for PD-L1 positive patients was 13.7 weeks versus 4.2 weeks for PD-L1 negative patients (ρ=0.08) nivolumab was well tolerated in our series of pediatric recurrent brain tumors with some transient partial responses in patients with positive PD-L1 expression and higher TMB. Our findings suggest that the use of immune checkpoint inhibitors in pediatric brain tumor patients should be limited to those with elevated PD-L1 expression and TMB.

Immunogenetics of glioblastoma: the future of personalized patient management

The prognosis of glioblastoma has changed little over the past two decades, with only minor improvements in length of overall survival through the addition of temozolomide (temodal) to standard of care and the recommended use of alternating electric field therapy (optune) to newly diagnosed patients. In an effort to define novel therapeutic targets across molecularly heterogeneous disease subgroups, researchers have begun to uncover the complex interplay between epigenetics, cell signaling, metabolism, and the immunosuppressive tumor microenvironment. Indeed, IDH mutations are now recognized as a defining differential factor not only influencing global hypermethylation and patient prognosis but also degree of immune infiltration within individual tumors. Likewise, next-generation sequencing has defined subgroup-specific transcriptional profiles that correlate with different mechanisms of immune evasion, including increased PD-L1 and CTLA-4 among mesenchymal tumors. Interestingly, sequencing of the T cell repertoire from numerous patient samples suggests that the correlation between mutational burden and enrichment of tumor-specific peptides may be less convincing than originally suspected. While this raises questions over the efficacy of dendritic cell or tumor-lysate vaccines and CAR-T therapies, these avenues continue to be explored. In addition to these active immunotherapies, inhibitors of molecular hubs with wide reaching effects, including STAT3, IDO, and TGF-β, are now in early-phase clinical trials. With the potential to block intrinsic biological properties of tumor growth and invasion while bolstering the immunogenic profile of the tumor microenvironment, these new targets represent a new direction for GBM therapies. In this review, we show the advances in molecular profiling and immunophenotyping of GBM, which may lead to the development of new personalized therapeutic strategies.

Using Smaller-Than-Standard Radiation Treatment Margins Does Not Change Survival Outcomes in Patients with High-Grade Gliomas

PURPOSE

The number of studies that evaluate treatment margins for high grade gliomas (HGG) are limited. We hypothesize that patients with HGG who are treated with a gross tumor volume (GTV) to planning tumor volume (PTV) expansion of ≤1 cm will have progression-free survival (PFS) and overall survival (OS) rates similar to those treated in accordance with standard protocols by the Radiation Therapy Oncology Group or European Organisation for Research and Treatment of Cancer. Furthermore, the PFS and OS of subgroups within the study population will have equivalent survival outcomes with GTV1-to-PTV1 margins of 1.0 cm and 0.4 cm.

METHODS AND MATERIALS

Treatment plans and outcomes for patients with pathologically confirmed HGG were analyzed (n = 267). Survival (PFS and OS) was calculated from the time of the first radiation treatment and a χ² test or Fisher exact test was used to calculate the associations between margin size and patient characteristics. Survival was estimated using Kaplan-Meier and compared using the log-rank test. All analyses were performed on the univariate level.

RESULTS

The median PFS and OS times were 10.6 and 19.1 months, respectively. By disease, the median PFS and OS times were 8.6 and 16.1 months for glioblastoma and 26.7 and 52.5 months for anaplastic glioma. The median follow-up time was 18.3 months. The treatment margin had no effect on outcome and the 1.0 cm GTV1-PTV1 margin subgroup (n = 212) showed median PFS and OS times of 10.7 and 19.1 months, respectively, and the 0.4 cm margin subgroup (n = 55) 10.2 and 19.3 months, respectively. In comparison with the standard treatment with 2 cm to 3 cm margins, there was not a significant difference in outcomes.

CONCLUSIONS

There is no apparent difference in survival when utilizing smaller versus larger margins as defined by the guidelines of the Radiation Therapy Oncology Group and European Organisation for Research and Treatment of Cancer. Although there remains no class I evidence that outcomes after treatment with smaller margins are identical to those after treatment with larger margins, this large series with long-term follow up suggests that a reduction of the margins is safe and further investigation is warranted.

Therapeutic Potential of Thymoquinone in Glioblastoma Treatment: Targeting Major Gliomagenesis Signaling Pathways

Glioblastoma multiforme (GBM) is one of the most devastating brain tumors with median survival of one year and presents unique challenges to therapy because of its aggressive behavior. Current treatment strategy involves surgery, radiotherapy, immunotherapy, and adjuvant chemotherapy even though optimal management requires a multidisciplinary approach and knowledge of potential complications from both the disease and its treatment. Thymoquinone (TQ), the main bioactive component of Nigella sativa L., has exhibited anticancer effects in numerous preclinical studies. Due to its multitargeting nature, TQ interferes in a wide range of tumorigenic processes and counteract carcinogenesis, malignant growth, invasion, migration, and angiogenesis. TQ can specifically sensitize tumor cells towards conventional cancer treatments and minimize therapy-associated toxic effects in normal cells. Its potential to enter brain via nasal pathway due to volatile nature of TQ adds another advantage in overcoming blood-brain barrier. In this review, we summarized the potential role of TQ in different signaling pathways in GBM that have undergone treatment with standard therapeutic modalities or with TQ. Altogether, we suggest further comprehensive evaluation of TQ in preclinical and clinical level to delineate its implied utility as novel therapeutics to combat the challenges for the treatment of GBM.

Current update of adoptive immunotherapy using cytokine-induced killer cells to eliminate malignant gliomas

The therapeutic outcome for those with malignant glioma is poor, even though diverse therapeutic modalities have been developed. Immunotherapy has emerged as a therapeutic approach for malignant gliomas, making it possible to selectively treat tumors while sparing normal tissue. Here, we review clinical trials of adoptive immunotherapy approaches for malignant gliomas. We also describe a clinical trial that examined the efficacy and safety of autologous cytokine-induced killer (CIK) cells along with concomitant chemoradiotherapy for newly diagnosed glioblastoma. These CIK cells identify and kill autologous tumor cells. This review focuses on the use of adoptive immunotherapy for malignant gliomas and reviews the current literature on the concept of antitumor activity mediated by CIK cells.

Recent advances and future of immunotherapy for glioblastoma

INTRODUCTION

Outcome for glioma (GBM) remains dismal despite advances in therapeutic interventions including chemotherapy, radiotherapy and surgical resection. The overall survival benefit observed with immunotherapies in cancers such as melanoma and prostate cancer has fuelled research into evaluating immunotherapies for GBM.

AREAS COVERED

Preclinical studies have brought a wealth of information for improving the prognosis of GBM and multiple clinical studies are evaluating a wide array of immunotherapies for GBM patients. This review highlights advances in the development of immunotherapeutic approaches. We discuss the strategies and outcomes of active and passive immunotherapies for GBM including vaccination strategies, gene therapy, check point blockade and adoptive T cell therapies. We also focus on immunoediting and tumor neoantigens that can impact the efficacy of immunotherapies.

EXPERT OPINION

Encouraging results have been observed with immunotherapeutic strategies; some clinical trials are reaching phase III. Significant progress has been made in unraveling the molecular and genetic heterogeneity of GBM and its implications to disease prognosis. There is now consensus related to the critical need to incorporate tumor heterogeneity into the design of therapeutic approaches. Recent data also indicates that an efficacious treatment strategy will need to be combinatorial and personalized to the tumor genetic signature.

Induction of eEF2-specific antitumor CTL responses in vivo by vaccination with eEF2-derived 9mer-peptides

Eukaryotic elongation factor 2 (eEF2) is an essential factor for protein synthesis. Previous studies have shown that the eEF2 gene was overexpressed and plays an oncogenic role in various types of cancers and that eEF2 gene product elicited both humoral immune responses to produce eEF2-specific IgG autoantibody in cancer-bearing individuals and cellular immune responses to induce eEF2 peptide-specific cytotoxic T lymphocytes (CTLs) in vitro. The purpose of the present study was to induce eEF2-specific, antitumor CTL responses in vivo by vaccination with MHC class I-binding eEF2-derived peptide. First, two mouse MHC class I-restricted eEF2‑derived, 9-mer peptides, EF17 (17-25 aa, ANIRNMSVI) and EF180 (180-188 aa, RIVENVNVI) were identified as eEF2-specific CTL peptides, and mice were vaccinated intradermally eight times with either EF17 or EF180 peptide emulsified with Montanide ISA51 adjuvant. Cytotoxicity assay showed that eEF2-specific CTLs were induced in both EF17‑and EF180‑vaccinated mice, and histological study showed no detectable damage in the organs of these mice. Next, to examine in vivo antitumor effects of eEF2 peptide vaccination in a therapeutic model, mice were vaccinated four times with one each of the two eEF2 peptides at weekly intervals after implantation of eEF2-expressing leukemia cells. The vaccination with eEF2 peptides induced eEF2-specific CTLs and suppressed tumor growth, and disease-free survival was significantly longer in EF180-vaccinated mice compared to control mice. The survival was associated with the robustness of eEF2-specific CTL induction. These results indicate that vaccination with MHC class I-binding eEF2 peptide induced eEF2-targeting, antitumor CTL responses in vivo without damage to normal organs, which provided us a rationale for eEF2 peptide-based cancer immunotherapy.