Dendritic cell vaccines for cancer therapy: Fundamentals and clinical trials

Abstract

One of the main challenges in antitumor immunotherapy is the low immunogenicity of tumor cells and the tolerogenic tumor microenvironment. The central role of dendritic cells (DCs), and the demonstration that ex vivo exposure of DC to tumor antigens was able to restore a specific T response, instigated the development of antitumor DC-based therapeutic vaccines. Several clinical trials have shown that DC vaccines are able to improve such clinical follow-up parameters as the decrease of serum tumor markers, disease stabilization, reduced disease relapse, low collateral effects, reduced death risk, and even tumor regression. However, the technical conditions for achieving vaccine efficacy is still not completely understood, since published protocols vary widely on precursor cell sources, differentiation and maturation conditions, antigen sources and loading methods, as well as administration routes. Despite these limitations, promising results stimulate the search for the best ways to improve tumor immunogenicity, DC antigen-presenting function, responsiveness of effector cells in the tumor microenvironment, as well as overcoming the tolerogenic or suppressive status of the patient‘s immune system.