Introduction: Cancer vaccines represent one of the oldest immunotherapy strategies. A variety of tumor-associated antigens have been exploited to investigate their immunogenicity as well as multiple strategies for vaccine administration. These efforts have led to the development of several clinical trials in tumors with different histological origins to test the clinical efficacy of cancer vaccines. However, suboptimal clinical results have been reported mainly due to the lack of optimized strategies to induce strong and sustained systemic tumor antigen-specific immune responses.
Areas covered: We provide an overview of different types of cancer vaccines that have been developed and used in the context of clinical studies. Moreover, we review different preclinical and clinical strategies pursued to enhance the immunogenicity, stability, and targeting at tumor site of cancer vaccines.
Expert opinion: Additional and appropriate preclinical studies are warranted to optimize the immunogenicity and delivery of cancer vaccines. The appropriate choice of target antigens is challenging; however, the exploitation of neoantigens generated from somatic mutations of tumor cells represents a promising approach to target highly immunogenic tumor-specific antigens. Remarkably, the investigation of the combination of cancer vaccines with immunomodulating agents able to skew the tumor microenvironment from immunosuppressive to immunostimulating will dramatically improve their clinical efficacy.
Keywords: Cancer vaccines; combination studies; immunogenicity; immunomodulating agents; neoantigens; tumor-associated antigens.