Comparison of four strategies for tumour vaccination in the B16-F10 melanoma model

We have compared four cell-based tumour vaccine strategies in prevention experiments using the B16-F10 melanoma model. Two of these are thought to favour the direct antigen presentation pathway (B16-F10 expressing B7.1 and hybrids made between B16-F10 cells and macrophages) and the other two strategies are thought to act by an indirect pathway of presentation (allogeneic tumour cells and autologous tumour cells combined with a powerful adjuvant (Provax-IDEC Pharmaceuticals)). Only the two latter vaccines promoted antitumour activity, whereas the vaccines consisting of B7.1-expressing tumour cells or the hybrid vaccine failed to provide any antitumour activity. Recently human trials have commenced using transfection of the B7.1 molecule, as well as employing the hybrid technology to make tumour-B cell hybrids or tumour and dendritic cell hybrids. Our results suggest that these approaches could be disappointing in the clinics if not optimised.