Advances in Experimental Targeted Therapy and Immunotherapy for Patients with Glioblastoma Multiforme

Abstract

Abstract. Glioblastoma multiforme (GBM) represents the most malignant primary brain tumor in adults with generally dismal prognosis, early clinical deterioration and high mortality. GBM is extremely invasive, characterized by intense and aberrant vascularization and high resistance to multimodal treatment. Standard therapy (surgery, radiotherapy and chemotherapy with temozolomide) has very limited effectiveness, with median overall survival of patients no longer than 15 months. Progress in genetics and epigenetics of GBM over the past decade has revealed various aberrations in cellular signaling pathways, the tumor microenvironment, and pathological angiogenesis. A number of targeted anticancer drugs, such as small-molecule kinase inhibitors and monoclonal antibodies, have been evaluated in clinical trials with newly-diagnosed, as well as recurrent GBM. Unfortunately, to date, only a single antiangiogenic agent, bevacizumab, has been approved for the treatment of recurrent GBM in the USA and Canada. The novel possibilities of cancer immunotherapy, especially immune checkpoint inhibitors, are being evaluated in clinical trials of patients with GBM. The most recent clinical experiences with targeted therapy as well as immunotherapy of GBM are given in this review. The relative lack of success of some of these approaches recently revealed in well-designed randomized clinical trials is also discussed.Glioblastoma multiforme (GBM) belongs to the largest group of primary central nervous system (CNS) tumors, so-called gliomas, which are formed from supporting glial cells in the brain parenchyma (1, 2). GBM represents the most common and most malignant tumor in this class, with an incidence of 3-4/100,000/year (3, 4). GBM is an extremely invasive and difficult to treat tumor, characterized by intense and aberrant vascularization and high resistance to radiotherapy (RT) and chemotherapy (CHT). The current standard of care for patients with newly-diagnosed GBM comprises of neurosurgery and subsequent concomitant chemoradiotherapy by fractionated external-beam RT and systemic temozolomide followed by systemic temozolomide in the adjuvant setting (5). There are only very limited possibilities for the treatment of subsequent recurrences, generally with minimal clinical efficacy (6). Despite intensive multimodal treatment strategies, the median survival of patients with GBM is still 12.1-14.6 months and only 3-5% of patients survive longer than 3 years (7).Enormous progress has been made in the genetics and epigenetics of GBM during the past decade. The Cancer 21Τhis article is freely accessible online.Correspondence to: Jiri Polivka, Department of Neurology, Faculty Hospital Plzen, alej Svobody 80, 304 60, Plzen, Czech Republic. E-mail: polivka@fnplzen.cz Key Words: Glioblastoma multiforme, GBM, targeted therapy, immunotherapy, immune checkpoint inhibitors, PD1 inhibition, CTLA4 inhibition, clinical trials, personalized medicine, review. ANTICANCER RESEARCH 37: 21-34 (2017) [8][9][10][11][12]. The most important genetic...

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