A randomized phase I/II trial of antitumor vaccination using the recombinant MAGE-A3 protein loaded on myeloid DC or mixed with adjuvant ASO2B in melanoma patients

2526 Background: The MAGE-A3 gene codes for tumor-specific antigens recognized by CD4+ and CD8+ T-cells. We and others previously reported trials with HLA class I-peptide loaded on autologous dendritic cells (DC) that induced specific T cells and occasional antitumor responses. This immune response was transient, possibly due to the lack of T-cell help. Here, we evaluated the potential advantage of the concurrent presentation of CD4+ and CD8+ epitopes on the recombinant (rec) MAGE-A3 protein loaded on myeloid DC, as compared to the protein combined with adjuvant AS02B. Methods: 19 patients (pts) with evaluable stage III or IV MAGE-A3 expressing melanoma received 4 vaccines (weeks 0, 2, 6, 10) of recMAGE-A3 protein either loaded on autologous non-mature DC (40–100 x 10E6 i.d./s.c.), or mixed with AS02B adjuvant (adj.) (300 μg of protein i.m.). DC were generated from adherent PBMC for 7 days with GM-CSF + IL-4, then pulsed with the protein for 1h. T-cell response was analyzed by Elispot after in vitro resti...