Mucosal Immunization for Cancer: Opportunities and Challenges

Cancer continues to be a large health and economic burden, despite advances in diagnostics and therapy. Cancer immunotherapy research and development of novel cancer vaccine strategies continues to grow, and new immunotherapy options offer considerable promise for patients. Research has identified more than four hundred tumor-associated antigens, yet only one cancer vaccine is FDA approved and on the market for established cancer. Since mucosal tissues are often the site of cancer development and metastasis, vaccine systems that induce tumor-specific mucosal immune responses are worthy of investigation. Mucosal immunization has the ability to induce tumor-specific immune responses in non-mucosal (systemic) sites while also inducing mucosal immune responses that are characterized by effector cells that home to and reside in mucosal tissues. The purpose of this review is to discuss recent preclinical advances with the use of mucosal immunization for the induction of protective anti-cancer immunity and discuss critical factors related to mucosal immunization, such as the route of immunization and adjuvants. Additionally, we will discuss challenges associated with translating effective mucosal vaccines for tumors from preclinical to clinical use. Finally, we will discuss the importance of preclinical and clinical studies to determine if mucosal immunization is critical for therapeutic benefit against tumors that arise at or metastasize to mucosal tissues.