Oral microparticulate vaccine for melanoma using M-cell targeting.

Cancer vaccines are limited in their use, because of their inability to mount a robust anti-tumor immune response. Thus, targeting M-cells in the small intestine, which are responsible for entry of many pathogens, will be an attractive way to elicit a strong immune response toward particulate antigens. Therefore, in the present investigation, we demonstrated that efficient oral vaccination against melanoma antigens could be accomplished by incorporating the antigens in an albumin-based microparticle with a ligand AAL (Aleuria aurantia lectin) targeted specifically to M-cells. The oral microparticulate vaccine effectively protected the mice from subcutaneous challenge with tumor cells in prophylactic settings. The animals were vaccinated with antigen microparticles having a size range of around 1-1.25 µm where one prime and four booster doses were administered every 14 days over 10 weeks of duration, followed by challenge with live tumor cells, which showed complete tumor protection after oral vaccination. With the inclusion of ligand in the microparticles, we observed significantly higher IgG titers (1565 μg/mL) as compared to the microparticle formulations without AAL (872 μg/mL). This data suggests that ligand loaded microparticles may have the potential to target antigens to M-cells for an efficient oral vaccination.