Contemporary Approaches to Immunotherapy of Solid Tumors

Simple Summary The last decade has seen dramatic changes in cancer treatment. Various methods of the immunotherapy of solid tumors, including treatment with targeted monoclonal antibodies, such as immune checkpoint inhibitors, bi- or trispecific immune cell enhancers, and antibody derivatives (e.g., antibody-drug conjugates), in addition to adoptive cell transfer or cell therapy, are being actively developed. A number of these approaches target tumor cells directly, while several other strategies aim to neutralize immunosuppressive elements in the tumor microenvironment (TME) and transform TME from immunologically "cold" to "hot". Although many of these approaches have received clinical approval, each has inherent limitations that are considered in this review. Additionally, we discuss recent innovations in immunotherapy to improve clinical efficacy in solid tumors and strategies to overcome the limitations of various immunotherapy.Abstract In recent years, the arrival of the immunotherapy industry has introduced the possibility of providing transformative, durable, and potentially curative outcomes for various forms of malignancies. However, further research has shown that there are a number of issues that significantly reduce the effectiveness of immunotherapy, especially in solid tumors. First of all, these problems are related to the protective mechanisms of the tumor and its microenvironment. Currently, major efforts are focused on overcoming protective mechanisms by using different adoptive cell therapy variants and modifications of genetically engineered constructs. In addition, a complex workforce is required to develop and implement these treatments. To overcome these significant challenges, innovative strategies and approaches are necessary to engineer more powerful variations of immunotherapy with improved antitumor activity and decreased toxicity. In this review, we discuss recent innovations in immunotherapy aimed at improving clinical efficacy in solid tumors, as well as strategies to overcome the limitations of various immunotherapies.