Extended survival and broad immune responses following vaccination of patients with metastatic melanoma with peptide-pulsed CD34+ progenitor derived dendritic cells (DCs)

2525 Background: Culture of CD34+ blood cells with GM-CSF, Flt-3 ligand and TNF yield distinct dendritic cell (DC) subtypes including Langerhans and interstitial DCs. Such composite DC vaccine was loaded with melanoma peptides (MART-1, tyrosinase, MAGE-3, gp100) and control antigens flu-matrix and KLH, and administered subcutaneously to patients with metastatic melanoma in a Phase I trial. Methods: HLA-A0201+patients received 4 DC vaccinations every 2 weeks followed by additional 4 monthly DC vaccinations. All DCs were pulsed with KLH, 20% of cells were pulsed with flu-matrix peptide and 80% with melanoma peptides. IFN-gamma ELISPOT and tetramer staining were used to measure specific CD8+ T cells. Spearman correlation was used with non-transformed data. Patient survival was calculated using Kaplan-Meier estimation based on log-rank analysis of difference. Results: There were 18 patients: 10 male with median age (range) was 53 (40–73) years. 6 patients had progressive melanoma after 4 vaccines and were rem...