Survivin as an immunotherapeutic target for adult and pediatric malignant brain tumors

Overview of role of survivin in cancer: expression, regulation, functions, and its potential as a therapeutic target

Survivin holds significant importance as a member of the inhibitor of apoptosis protein (IAP) family due to its predominant expression in tumours rather than normal terminally differentiated adult tissues. The high expression level of survivin in tumours is closely linked to chemotherapy resistance, heightened tumour recurrence, and increased tumour aggressiveness and serves as a negative prognostic factor for cancer patients. Consequently, survivin has emerged as a promising therapeutic target for cancer treatment. In this review, we delve into the various biological characteristics of survivin in cancers and its pivotal role in maintaining immune system homeostasis. Additionally, we explore different therapeutic strategies aimed at targeting survivin.

Impact of General Factors on Glioma Immunotherapy

Glioma remains the most common malignant tumor in the brain and is also the most difficult to treat. Immunotherapy achieving long-lasting tumor remission in multiple cancer types has received considerable attention due to its potential to improve the treatment outcomes of patients with glioma. However, clinical trials have not yet demonstrated major improvements in prognoses, which might be attributable to the extrinsic components and intrinsic mechanisms involved in the tumor microenvironment and immune system. It is particularly noteworthy that there is emerging evidence that current routine treatment modalities and the physical and psychological characteristics of patients have different impacts on the efficacy of glioma immunotherapy. This article addresses how these factors interact with the host immune system and tumor microenvironment, and highlights their potential roles in glioma immunotherapy, with the ultimate goal of developing better immunotherapy-based personalized medicine strategies.

T-Cell Immunotherapy for Pediatric High-Grade Gliomas: New Insights to Overcoming Therapeutic Challenges

Despite decades of research, pediatric central nervous system (CNS) tumors remain the most debilitating, difficult to treat, and deadliest cancers. Current therapies, including radiation, chemotherapy, and/or surgery, are unable to cure these diseases and are associated with serious adverse effects and long-term impairments. Immunotherapy using chimeric antigen receptor (CAR) T cells has the potential to elucidate therapeutic antitumor immune responses that improve survival without the devastating adverse effects associated with other therapies. Yet, despite the outstanding performance of CAR T cells against hematologic malignancies, they have shown little success targeting brain tumors. This lack of efficacy is due to a scarcity of targetable antigens, interactions with the immune microenvironment, and physical and biological barriers limiting the homing and trafficking of CAR T cells to brain tumors. In this review, we summarize experiences with CAR T-cell therapy for pediatric CNS tumors in preclinical and clinical settings and focus on the current roadblocks and novel strategies to potentially overcome those therapeutic challenges.

Irradiation to Improve the Response to Immunotherapeutic Agents in Glioblastomas

Purpose

Glioblastoma (GBM) remains an incurable disease despite extensive treatment with surgical resection, irradiation, and temozolomide. In line with many other forms of aggressive cancers, GBM is currently under consideration as a target for immunotherapy. However, GBM tends to be nonimmunogenic and exhibits a microenvironment with few or no effector T cells, a relatively low nonsynonymous somatic mutational load, and a low predicted neoantigen burden. GBM also exploits a multitude of immunosuppressive strategies.

Methods and Materials

A number of immunotherapeutic approaches have been tested with disappointing results. A rationale exists to combine immunotherapy and radiation therapy, which can induce an immunogenic form of cell death with T-cell activation and tumor infiltration.

Results

Various immunotherapy agents, including immune checkpoint modulators, transforming growth factor beta receptor inhibitors, and indoleamine-2,3-dioxygenase inhibitors, have been evaluated with irradiation in preclinical GBM models, with promising results, and are being further tested in clinical trials.

Conclusions

This review aims to present the basic rationale behind this emerging complementary therapeutic approach in GBM, appraise the current preclinical and clinical data, and discuss the future challenges in improving the antitumor immune response.

Quo Vadis-Do Immunotherapies Have a Role in Glioblastoma?

PURPOSE OF REVIEW

More effective therapies for glioblastoma are urgently needed. Immunotherapeutic strategies appear particularly promising and are therefore intensively studied. This article reviews the current understanding of the immunosuppressive glioblastoma microenvironment, discusses the rationale behind various immunotherapies, and outlines the findings of several recently published clinical studies.

RECENT FINDINGS

The results of CheckMate-143 indicated that nivolumab is not superior to bevacizumab in patients with recurrent glioblastoma. A first-in man exploratory study evaluating EGFRvIII-specific CAR T cells for patients with newly diagnosed glioblastoma demonstrated overall safety of CAR T cell therapy and effective target recognition. A pilot study evaluating treatment with adoptively transferred CMV-specific T cells combined with a CMV-specific DC vaccine was found to be safe and resulted in increased polyclonality of CMV-specific T cells in vivo. Despite the success of immunotherapies in many cancers, clinical evidence supporting their efficacy for patients with glioblastoma is still lacking. Nevertheless, the recently published studies provide important proof-of-concept in several areas of immunotherapy research. The careful and critical interpretation of these results will enhance our understanding of the opportunities and challenges of immunotherapies for high-grade gliomas and improve the immunotherapeutic strategies investigated in future clinical trials.

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

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

Vaccination strategies for neuro-oncology

Vaccination against cancer-associated antigens has long held the promise of inducting potent antitumor immunity, targeted cytotoxicity while sparing normal tissues, and long-lasting immunologic memory that can provide surveillance against tumor recurrence. Evaluation of vaccination strategies in preclinical brain tumor models has borne out the capacity for the immune system to effectively and safely eradicate established tumors within the central nervous system. Early phase clinical trials have established the feasibility, safety, and immunogenicity of several vaccine platforms, predominantly in patients with glioblastoma. Definitive demonstration of clinical benefit awaits further study, but initial results have been encouraging. With increased understanding of the stimulatory and regulatory pathways that govern immunologic responses and the enhanced capacity to identify novel antigenic targets using genomic interrogation of tumor cells, vaccination platforms for patients with malignant brain tumors are advancing with increasing personalized complexity and integration into combinatorial treatment paradigms.

Advances and challenges: dendritic cell vaccination strategies for glioblastoma

INTRODUCTION

Glioblastoma is the most common primary brain tumor in adults and prognosis remains poor with a median survival of approximately 15-17 months. This review provides an overview of recent advances in the field of glioblastoma immunotherapy. Areas covered: Recent advances in dendritic cell vaccination immunotherapy are showing encouraging results in clinical trials and promise to extend patient survival. In this report we discuss current scientific knowledge regarding dendritic cell (DC) vaccines, including approaches to differentiating, priming, and injecting dendritic cells to achieve maximal anti-tumor efficacy in glioblastoma. These findings are compared to recently completed and currently ongoing glioblastoma clinical trials. Novel methods such as 'fastDCs' and vaccines targeting DCs in-vivo may offer more effective treatment when compared to traditional DC vaccines and have already entered the clinic. Expert commentary: Finally, we discuss the challenges of T-cell dysfunctions caused by glioblastoma immunosuppression and how they affect dendritic cell vaccinations approaches.

Ex vivo generation of dendritic cells from cryopreserved, post-induction chemotherapy, mobilized leukapheresis from pediatric patients with medulloblastoma

Generation of patient-derived, autologous dendritic cells (DCs) is a critical component of cancer immunotherapy with ex vivo-generated, tumor antigen-loaded DCs. An important factor in the ability to generate DCs is the potential impact of prior therapies on DC phenotype and function. We investigated the ability to generate DCs using cells harvested from pediatric patients with medulloblastoma for potential evaluation of DC-RNA based vaccination approach in this patient population. Cells harvested from medulloblastoma patient leukapheresis following induction chemotherapy and granulocyte colony stimulating factor mobilization were cryopreserved prior to use in DC generation. DCs were generated from the adherent CD14+ monocytes using standard procedures and analyzed for cell recovery, phenotype and function. To summarize, 4 out of 5 patients (80%) had sufficient monocyte recovery to permit DC generation, and we were able to generate DCs from 3 out of these 4 patient samples (75%). Overall, we successfully generated DCs that met phenotypic requisites for DC-based cancer therapy from 3 out of 5 (60%) patient samples and met both phenotypic and functional requisites from 2 out of 5 (40%) patient samples. This study highlights the potential to generate functional DCs for further clinical treatments from refractory patients that have been heavily pretreated with myelosuppressive chemotherapy. Here we demonstrate the utility of evaluating the effect of the currently employed standard-of-care therapies on the ex vivo generation of DCs for DC-based clinical studies in cancer patients.

Survivin beyond physiology: orchestration of multistep carcinogenesis and therapeutic potentials

Survivin, a member of the inhibitor of apoptosis protein family, has been associated with protection from cell apoptosis and regulation of mitosis. Survivin exhibits low to undetectable expression in most finally differentiated adult tissues but is abundantly over-expressed in almost all cancers. The aberrant high expression of survivin in cancers is associated with advanced disease, increased rate of tumor recurrence, abbreviated overall survival and resistance to chemo- and radio- therapy. Survivin touches nearly every aspect of cancer and is involved in the initiation, maintenance and development of tumor. Therefore, its significance in cancer dictates the pursuit for anti-survivin cancer therapies.

Inhibitor of apoptosis proteins (IAPs) as regulatory factors of hepatic apoptosis

IAPs are a group of regulatory proteins that are structurally related. Their conserved homologues have been identified in various organisms. In human, eight IAP members have been recognized based on baculoviral IAP repeat (BIR) domains. IAPs are key regulators of apoptosis, cytokinesis and signal transduction. The antiapoptotic property of IAPs depends on their professional role for caspases. IAPs are functionally non-equivalent and regulate effector caspases through distinct mechanisms. IAPs impede apoptotic process via membrane receptor-dependent (extrinsic) cascade and mitochondrial dependent (intrinsic) pathway. IAP-mediated apoptosis affects the progression of liver diseases. Therapeutic options of liver diseases may depend on the understanding toward mechanisms of the IAP-mediated apoptosis.

Survivin expression in medulloblastoma: a possible marker for survival

Medulloblastomas are highly invasive tumors which are generally disseminated at the time of diagnosis. High and continued morbidity and mortality have prompted the search for new biologic markers that might be used for targeted therapy to minimise treatment related side effects. In this work, we studied the positive expression of survivin in medulloblastoma and investigated its relation to clinical, pathologic data and survival. Tumor tissue specimens from 47 patients with medulloblastoma who underwent primary surgical treatment from June 2002 to June 2006 at the Mansoura university hospital, Egypt were collected. Paraffin sections of all samples were submitted for immunohistochemistry using anti-survivin antibody. The relation between the percentage of positive survivin cells with clinical, pathological and survival data was evaluated.

RESULTS

In 47 cancer tissue specimens, one case large-cell-anaplastic (1.12 %), tweleve cases desmoplastic (25.53 %) and 34 cases classic medulloblastomas (72.34 %). The immunohistochemical expression of survivin was nulear with moderate intensity. It does not correlate with either age or sex. There was a significant negative correlation of survivin expression with survival (p < 0.001), where negative survivin immunostaining was associated with prolonged overall and disease free survival, while survivin expression was associated with shortened survival.

CONCLUSION

Survivin expression correlate with the clinical outcome with poor prognosis and could be a potential predictive factor for recurrence or metastasis.

Antigens in chronic myeloid leukemia: implications for vaccine development

Treatment with imatinib mesylate and other tyrosine kinase inhibitors (TKI) revolutionized the therapy of chronic myeloid leukemia (CML). However, it alone does not cure this disease. Moreover, some patients develop resistance or adverse effects to this therapy. As successful treatment of a portion of CML patients by hematopoietic stem cell transplantation (HSCT) suggests the importance of immune mechanisms in the elimination of leukemic cells, including leukemia stem cells, TKI administration or HSCT might be combined with vaccination to cure CML patients. However, antigens implicated in the immune responses have not yet been sufficiently identified. Therefore, in this report, we compiled and characterized a list of 165 antigens associated with CML (CML-Ag165) and analyzed the expression of the corresponding genes in CML phases, subpopulations of leukemic cells, and CML-derived cell lines using available datasets from microarray transcriptional-profiling studies. From the CML-Ag165 list, we selected antigens most suitable for vaccine development and evaluated their appropriate characteristics.