Vaccine-based immunotherapeutic approaches to gliomas and beyond

Current state and future prospects of immunotherapy for glioma

There is a large unmet need for effective therapeutic approaches for glioma, the most malignant brain tumor. Clinical and preclinical studies have enormously expanded our knowledge about the molecular aspects of this deadly disease and its interaction with the host immune system. In this review we highlight the wide array of immunotherapeutic interventions that are currently being tested in glioma patients. Given the molecular heterogeneity, tumor immunoediting and the profound immunosuppression that characterize glioma, it has become clear that combinatorial approaches targeting multiple pathways tailored to the genetic signature of the tumor will be required in order to achieve optimal therapeutic efficacy.

Role of the blood-brain barrier in metastatic disease of the central nervous system

Systemic therapy is an important backbone in the multimodal treatment approach of brain metastases. However, the blood-brain barrier or, more correctly, the blood-tumor barrier, as the properties of tumor-associated vessels differ from the physiologic state, potentially limits the passage of systemic drugs. Indeed, several preclinical and clinical investigations showed that the distribution of drugs is very heterogeneous within a given brain metastasis, despite the contrast enhancement in magnetic resonance imaging. Brain metastases may show lower intratumoral concentrations of some drugs as compared to extracranial tumor sites, resulting in mixed responses. Therefore, a more profound understanding of the role of the blood-brain/blood-tumor barrier is needed to effectively formulate clinical trial approaches on systemic therapy options in patients with brain metastases.

Gene Expression and Methylation Analyses Suggest DCTD as a Prognostic Factor in Malignant Glioma

Malignant glioma is the most common brain cancer with dismal outcomes. Individual variation of the patients’ survival times is remarkable. Here, we investigated the transcriptome and promoter methylation differences between patients of malignant glioma with short (less than one year) and the patients with long (more than three years) survival in CGGA (Chinese Glioma Genome Atlas), and validated the differences in TCGA (The Cancer Genome Atlas) to identify the genes whose expression levels showed high concordance with prognosis of glioma patients, as well as played an important role in malignant progression. The gene coding a key enzyme in genetic material synthesis, dCMP deaminase (DCTD), was found to be significantly correlated with overall survival and high level of DCTD mRNA indicated shorter survival of the patients with malignant glioma in different databases. Our finding revealed DCTD as an efficient prognostic factor for malignant glioma. As DCTD inhibitor gemcitabine has been proposed as an adjuvant therapy for malignant glioma, our finding also suggests a therapeutic value of gemcitabine for the patients with high expression level of DCTD.

Trial Watch: Immunostimulatory monoclonal antibodies for oncological indications

The goal of cancer immunotherapy is to establish new or boost pre-existing anticancer immune responses that eradicate malignant cells while generating immunological memory to prevent disease relapse. Over the past few years, immunomodulatory monoclonal antibodies (mAbs) that block co-inhibitory receptors on immune effectors cells - such as cytotoxic T lymphocyte-associated protein 4 (CTLA4), programmed cell death 1 (PDCD1, best known as PD-1) - or their ligands - such as CD274 (best known as PD-L1) - have proven very successful in this sense. As a consequence, many of such immune checkpoint blockers (ICBs) have already entered the clinical practice for various oncological indications. Considerable attention is currently being attracted by a second group of immunomodulatory mAbs, which are conceived to activate co-stimulatory receptors on immune effector cells. Here, we discuss the mechanisms of action of these immunostimulatory mAbs and summarize recent progress in their preclinical and clinical development.

Pharmacotherapy of Glioblastoma: Established Treatments and Emerging Concepts

Glioblastoma is the most frequent malignant brain tumor and is characterized by poor prognosis, increased invasiveness, and high recurrence rates. Standard treatment for glioblastoma includes maximal safe surgical resection, radiation, and chemotherapy with temozolomide. Despite treatment advances, only 15-20% of glioblastoma patients survive to 5 years, and no therapies have demonstrated a durable survival benefit in recurrent disease. In the last 10 years, significant advances in knowledge of the biology and molecular pathology of the malignancy have opened the way to new treatment options. Clinical management of patients (pseudo-progressions, side effects of therapies, best supportive care, centralization in expertise care centers) has improved. In brain tumors, such as in other solid tumors, we have entered an era of immune-oncology. Immunotherapy seems to have an acceptable safety and tolerability profile in the recurrent setting and is under investigation in clinical trials in newly diagnosed glioblastoma patients. This review focuses on novel targeted therapies recently developed for the management of newly diagnosed and recurrent glioblastomas.