CTLA4 and melanoma: Previously, we have shown that the therapeutic efficacy of CTLA-4 blockade against poorly immunogenic tumors like B16 melanoma is strongly enhanced by co-administration of an autologous tumor vaccine expressing either the cytokine Granulocyte-macrophage colony-stimulating factor (GM-CSF) or FMS-like tyrosine kinase 3 ligand (Flt3-ligand) [4], [5].