Cancer Immunotherapy: Diverse Approaches and Obstacles

Cancer immunotherapy approaches have progressed significantly during the last decade due to the significant improvement of our understanding of immunologic evasion of malignant cells. Depending on the type, stage, and grade of cancer, distinct immunotherapy approaches are being designed and recommended; each is different in efficacy and adverse effects. Malignant cells can adopt multiple strategies to alter the normal functioning of the immune system in recognizing and eliminating them. These strategies include secreting different immunosuppressive factors, polarizing tumor microenvironment cells to immunosuppressive ones, and interfering with the normal function of the antigen processing machinery (APM). In this context, careful evaluation of immune surveillance has led to a better understanding of the roles of cytokines, including IL-2, IL-12, IL-15, interferon-α (IFN-α), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) in cancer formation and their potential application in cancer immunotherapy. Additionally, monoclonal antibodies (mAbs), adoptive cell therapy approaches, immune checkpoint blockade, and cancer vaccines also play significant roles in cancer immunotherapy. Moreover, the development of clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/CAS9) as an outstanding genome editing tool resolved many obstacles in cancer immunotherapy. In this regard, this review aimed to investigate the impacts of different immunotherapy approaches and their potential roles in the current and future roads of cancer treatment. Whatever the underlying solution for treating highly malignant cancers is, it seems that solving the question is nowhere near an achievement unless the precise cooperation of basic science knowledge with our translational experience.