Applications of built-in adjuvants in anti-tumor carbohydrate and glycopeptide vaccines

Carbohydrate and glycopeptide vaccines have shown great promise in tumor prevention and treatment. However, their relatively low immunogenicity remains a significant challenge. To address this, adjuvants are commonly employed to enhance immune responses against specific antigens. Despite their widespread use, conventional adjuvants still face several limitations, including limited immune stimulation and potential safety concerns associated with molecular diffusion. A promising strategy to overcome these challenges is the incorporation of built-in adjuvants, which promotes adjuvants to augment their immunostimulatory effect. This review highlights the application of various immune agonists as built-in adjuvants to enhance vaccine immunogenicity, including Toll-like receptor (TLR) agonists, invariant natural killer T (iNKT) cell agonists, stimulator of interferon genes (STING) agonists, nucleotide-binding oligomerization domain-like receptors (NLR) agonists, and C-type lectin receptor (CLR) agonists. By summarizing recent advancements in this field, we provide valuable insights into the development of more effective and safer carbohydrate vaccines.