Synthesis of Heptasaccharide RM2 Prostate Tumor Antigen: Chemical Synthesis of Heptasaccharide and Tetrasaccharide (Inner Core of the RM2 Antigen)

Abstract

Among the DT-TR_8.1 and DT-RM_4.7 vaccinated groups, previous studies have shown that a strong binding to trisaccharide 1-51 and a lesser extent to tetrasaccharide 1-52, pentasaccharide 1-53, pentasaccharide 1-54, and hexasacharide 1-1 epitopes were observed in both C1- and C34-adjuvanted vaccines. Above all, the specificity analysis of the induced IgG antibodies by vaccines showed that the induced antibodies had strong binding to these oligosaccharides containing the same epitope trisaccharide 1-51 (NeuAcα2→6GlcNAcβ1→3Galβ1→R). Furthermore, RM2 is identified as a novel hybrid structure between “ganglio-series” and the “disialyl lacto-series type 1 chain” groups. We had the interest to chemically synthesize the proposed heptasaccharide 3-5 and tetrasaccharide 3-6 to further evaluate the importance of the inner core of the RM2 antigen.