A Stable Nano-Vaccine for the Targeted Delivery of Tumor-Associated Glycopeptide Antigens

Abstract

We have developed a novel antigen delivery system based on polysaccharide-coated gold nanoparticles (AuNPs) targeted to antigen presenting cells (APCs) expressing Dectin-1. AuNPs were synthesized de-novo using yeast-derived beta-1,3-glucans (B13Gs) as the reductant and passivating agent in a microwave-catalyzed procedure yielding highly uniform and serum-stable particles. These were further functionalized with both peptides and glycopeptides from the tandem repeat sequence of mucin 4 (MUC4), a glycoprotein overexpressed in pancreatic tumors. The glycosylated sequence contained the Thomsen-Friedenreich disaccharide, a pan-carcinoma, tumor-associated carbohydrate antigen which has been a traditional target for antitumor vaccine design. These motifs were prepared with a cathepsin D protease cleavage site (Gly-Phe-Leu-Gly), loaded on the B13Gs-coated particles and these constructs were examined for Dectin-1 binding, APC processing and presentation in a model in vitro system and for immune responses in mice. We showed that these particles elicit strong in vivo immune responses through the production of both high-titer antibodies and priming of antigen-recognizing T-cells by ELISPOT analysis. Further examination showed that a favorable antitumor balance of expressed cytokines was generated, with little or no expression of immunosuppressive Il-10. This system is modular in that any range of antigens can be conjugated to our particles and efficiently delivered to APCs expressing Dectin-1.

Structure Guided Design of Bacteriophage Qβ Mutants as Next Generation Carriers for Conjugate Vaccines

“…Many carriers have been investigated, such as nanomaterials, 7 liposomes and proteoliposomes, 8 polysaccharides, 9 dendrimers, 10 and immunogenic proteins including keyhole limpet hemocyanin (KLH), 11,12 tetanus toxoid (TT), 13 and cross reactive material-197 (CRM-197). 14,15 KLH, 16 a large glycoprotein, is the most advanced carrier for cancer vaccine studies, as multiple KLH-TACA conjugates have been evaluated in late-stage clinical trials.…”

“…As TACAs alone cannot generate effective anticancer immune responses, carriers are critical for TACA-based vaccine design. Many carriers have been investigated, such as nanomaterials, liposomes and proteoliposomes, polysaccharides, dendrimers, and immunogenic proteins including keyhole limpet hemocyanin (KLH), , tetanus toxoid (TT), and cross reactive material-197 (CRM-197). , KLH, a large glycoprotein, is the most advanced carrier for cancer vaccine studies, as multiple KLH-TACA conjugates have been evaluated in late-stage clinical trials. , Clinical studies have shown that cancer patients capable of producing high levels of anti-TACA antibodies following KLH-TACA immunization are associated with better prognosis and survival. , However, for the full patient cohort, vaccination failed to exhibit statistically significant protection , highlighting the critical need to improve levels of anti-TACA antibodies produced.…”