A cohort pilot study on therapeutic vaccination of advanced melanoma patients with dendritic cells loaded with multiple peptides or electroporated with mRNA

18011 Background: Therapeutic vaccination of melanoma patients with tumor specific antigenic peptides has been associated with increased frequency of anti-vaccine CTL precursor frequencies in peripheral blood and objective tumor regression in a low percentage of patients. Methods: We investigated the safety and activity of two autologous dendritic cell-based vaccines in 2 sequential cohorts of advanced melanoma patients. Patients first underwent a leucapheresis. Following enrichment in a semi-closed culture system using Cell Factories (Nunc), adherent cells were cultured in RPMI 1640 medium supplemented with 1% heat-inactivated autologous plasma, 500U/ml IL-4 and 1000 U/ml GM-CSF for 6 days and cryo-preserved. Upon thawing, DC were pulsed with 8 peptides or electroporated with synthetic mRNA encoding 7 antigens. Dendritic cell vaccines were administered by intradermal and subcutaneous biweekly injections for a total of 6 times (= cycle 1). Thereafter vaccination was repeated every 6w until clinical deteri...