Synthesis of a Liposomal MUC1 Glycopeptide-Based Immunotherapeutic and Evaluation of the Effect of l‑Rhamnose Targeting on Cellular Immune Responses

• Published in: Bioconjugate chemistry 2016-01, Vol.27 (1), p.110-120
• Main Authors: Karmakar, Partha, Lee, Kyunghee, Sarkar, Sourav, Wall, Katherine A, Sucheck, Steven J
• Format: Article
• Language: English
• Subjects: Amino acids; Animals; Antigen presentation; Biosynthesis; Cancer Vaccines - immunology; CD8-Positive T-Lymphocytes - drug effects; CD8-Positive T-Lymphocytes - immunology; Cell Proliferation; Chemistry Techniques, Synthetic; Cholesterol - chemistry; Epitopes - genetics; Epitopes - immunology; Female; Immunization; Immunoconjugates - chemistry; Immunoconjugates - pharmacology; Immunogenicity; Immunotherapy; Interferon-gamma - metabolism; Liposomes - chemistry; Lymphocytes; Maturation; Mice, Inbred C57BL; Mucin-1 - chemistry; Mucin-1 - immunology; Peptides; Protein Engineering - methods; Rhamnose - immunology; Vaccines; Vaccines - immunology
• ISSN: 1043-1802; 1520-4812
• DOI: 10.1021/acs.bioconjchem.5b00528

Generation of a CD8+ response to extracellular antigen requires processing of the antigen by antigen presenting cells (APC) and cross-presentation to CD8+ T cell receptors via MHC class I molecules. Cross-presentation is facilitated by efficient antigen uptake followed by immune-complex-mediated maturation of the APCs. We hypothesize that improved antigen uptake of a glycopeptide sequence containing a CD8+ T cell epitope could be achieved by delivering it on a liposome surface decorated with an immune complex-targeting ligand, an l-Rhamnose (Rha) epitope. We synthesized a 20-amino-acid glycopeptide TSAPDT­(GalNAc)­RPAPGSTAPPAHGV from the variable number tandem repeat region of the tumor marker MUC1 containing an N-terminal azido moiety and a tumor-associated α-N-acetyl galactosamine (GalNAc) at the immunogenic DTR motif. The MUC1 antigen was attached to Pam3Cys, a Toll-like receptor-2 ligand via copper­(I)-catalyzed azido-alkyne cycloaddition (CuAAc) chemistry. The Rha-decorated liposomal Pam3Cys-MUC1-Tn 4 vaccine was evaluated in groups of C57BL/6 mice. Some groups were previously immunized to generate anti-Rha antibodies. Anti-Rha antibody expressing mice that received the Rha liposomal vaccine showed higher cellular immunogenicity compared to the control group while maintaining a strong humoral response.