In order to evaluate the suitability of nucleic acid-based vaccination, in a clinical phase I/II trial that enrolled stage IV melanoma patients, monocyte-derived DC were transfected in vitro with pDNA encoding melanoma-associated antigens melan A and gp100 using a cationic peptide for pDNA transfer, and chloroquine to promote endosomal escape, and were stimulated with TNF (tumor necrosis factor)-α and IL-1β [56]. Here, PMEL is linked to melanoma.