GM3 ganglioside: a novel target for the therapy against melanoma

Malignant melanoma is a tumor with a steeply increasing incidence and scarce therapeutic options once metastatic. Currently, no vaccine is widely commercially available for melanoma treatment or prevention. The overexpression of GM3 ganglioside in murine and human melanomas and its important role in tumor progression makes this self antigen a potential target for preventive immunotherapy of this neoplasm. Previously, we have shown that preventive vaccination with GM3/VSSP induced a specific antitumor response; and elicited the rejection of syngeneic GM3-positive melanoma cells in immunized mice. In the present paper, we published the induction of a potent antitumor effect of this vaccine administered in a minimal residual disease B16 melanoma model. These findings propose the GM3/VSSP vaccine as a therapy designed to elicit and/or boost antitumor immunity in patients with minimal residual disease after surgery; thereby preventing or prolonging the time to recurrence. This is an important issue of the clinical setting because patients with stage II melanoma were reported to have 60% chance of survival 5 years after surgery. In addition, we examined the mechanisms by which this immunogen confers tumor protection. Surprisingly, in spite of the glycolipidic nature of this antigen, we have found that induction of anti-GM3 IgG antibodies and tumor- specific IFN γ secreting CD8+ T cells correlated with tumor protection. As a result, these findings demonstrate, for the first time, the direct involvement of the cellular immune response in the anti-tumor protection induced by a ganglioside-based vaccine