cells Review Immunotherapy of Glioblastoma: Current Strategies and Challenges in Tumor Model Development Bernarda Majc 1,2, Metka Novak 1, Nataša Kopitar-Jerala 3 , Anahid Jewett 4 and Barbara Breznik 1,* 1 Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, 111 Veˇcnapot, SI-1000 Ljubljana, Slovenia;
[email protected] (B.M.);
[email protected] (M.N.) 2 International Postgraduate School Jozef Stefan, 39 Jamova ulica, SI-1000 Ljubljana, Slovenia 3 Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute, 39 Jamova ulica, SI-1000 Ljubljana, Slovenia;
[email protected] 4 Division of Oral Biology and Medicine, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, University of California School of Dentistry, 10833 Le Conte Ave, Los Angeles, CA 90095, USA;
[email protected] * Correspondence:
[email protected]; Tel.: +386-59-232-870 Abstract: Glioblastoma is the most common brain malignant tumor in the adult population, and im- munotherapy is playing an increasingly central role in the treatment of many cancers. Nevertheless, the search for effective immunotherapeutic approaches for glioblastoma patients continues. The goal of immunotherapy is to promote tumor eradication, boost the patient’s innate and adaptive immune responses, and overcome tumor immune resistance. A range of new, promising immunotherapeutic strategies has been applied for glioblastoma, including vaccines, oncolytic viruses, immune check- point inhibitors, and adoptive cell transfer. However, the main challenges of immunotherapy for glioblastoma are the intracranial location and heterogeneity of the tumor as well as the unique, immunosuppressive tumor microenvironment. Owing to the lack of appropriate tumor models, there are discrepancies in the efficiency of various immunotherapeutic strategies between preclinical Citation: Majc, B.; Novak, M.; studies (with in vitro and animal models) on the one hand and clinical studies (on humans) on the Kopitar-Jerala, N.; Jewett, A.; Breznik, other hand.