Beyond the blood-brain barrier: Intranasal vaccines in cancer immunotherapy.

Cancer remains one of the most challenging diseases to treat, with a wide range of therapeutic approaches being explored. Immunotherapy has emerged as a promising strategy, leveraging the body's immune system to target and eliminate cancer cells. Intranasal vaccination, a non-invasive method that triggers mucosal immunity, has gained attention for its potential in treating cancers. This approach involves the administration of vaccines through the nasal route, where they stimulate a localised immune response in the mucosal membranes, particularly in the respiratory tract. The nasal cavity's rich presence of dendritic cells (DCs) makes it an ideal site for initiating strong immune defences against pathogens that enter through respiratory pathways. This method also offers the advantage of bypassing the blood-brain barrier (BBB), enhancing drug absorption, and providing a quicker pharmacological effect than other delivery methods. Several studies have shown promising results in animal models, where intranasal vaccines have effectively treated various cancers, including melanoma and breast cancer. However, the development and approval of intranasal vaccines face significant regulatory challenges. Vaccine developers must ensure the stability and potency of the formulation, meet stringent regulatory requirements, and engage in ongoing discussions with regulatory agencies throughout the clinical trial phases. Despite these challenges, the potential of intranasal vaccines to elicit a protective mucosal antitumor immune response presents a promising avenue for future cancer therapies. The present state of intranasal cancer vaccines is reviewed in this paper, along with immune activation mechanisms, vaccination platforms, adjuvants, regulatory issues, and possible remedies.