Structural study of liposomes loaded with a GM3 lactone analogue for the targeting of tumor epitopes

Therapeutic vaccination with tumor antigens is a new approach in cancer treatment, which aims at inducing immune response while avoiding the side effects generally associated to many conventional therapies. To improve the efficacy of vaccines, suitable carriers may be used. Herein the insertion of a thioether analogue of GM3 lactone (SNeuAC-C14) into liposomes is reported. SNeuAC-C14 is a potential vaccine for the targeting of saccharide-based tumor epitopes. Different liposome formulations were designed to act as carriers and to generate recognition by tumor epitopes. The structural study of pure and loaded liposomes was carried out by synchrotron Small Angle X-ray Scattering and was complemented by Dynamic Light Scattering and Zeta potential measurements. This provided detailed information on relevant properties of the investigated host-guest structures and showed that the active unit of SNeuAC-C14, i.e. its spiro tricyclic moiety, was located in the polar head region of the liposome bilayer, which is an important requirement for recognition phenomena. Moreover, it was found that most of the SNeuAC-C14/liposome complexes were positively charged. The obtained results allow these systems to be considered as candidates to promote immunoresponse in tumor cells.