Data from Effect of Granulocyte/Macrophage Colony-Stimulating Factor on Circulating CD8+ and CD4+ T-Cell Responses to a Multipeptide Melanoma Vaccine: Outcome of a Multicenter Randomized Trial

Purpose: Granulocyte/macrophage colony-stimulating factor (GM-CSF) administered locally together with vaccines can augment T-cell responses in animal models. Human experience has been limited to small and uncontrolled trials. Thus, a multicenter randomized phase II trial was done to determine whether local administration of GM-CSF augments immunogenicity of a multipeptide vaccine. It also assessed immunogenicity of administration in one versus two vaccine sites.Experimental Design: One hundred twenty-one eligible patients with resected stage IIB to IV melanoma were vaccinated with 12 MHC class Irestricted melanoma peptides to stimulate CD8+ T cells plus a HLA-DRrestricted tetanus helper peptide to stimulate CD4+ T cells, emulsified in incomplete Freund's adjuvant, with or without 110 g GM-CSF. Among 119 evaluable patients, T-cell responses were assessed by IFN- ELIspot assay and tetramer analysis. Clinical outcomes were recorded.Results: CD8+ T-cell response rates to the 12 MHC class Irestricted melanoma peptides (by day 50) with or without GM-CSF were 34 and 73, respectively (P < 0.001), by direct ELIspot assay. Tetramer analyses corroborated the functional data. CD4+ T-cell responses to tetanus helper peptide were higher without GM-CSF (95 versus 77; P = 0.005). There was no significant difference by number of vaccine sites. Three-year overall and disease-free survival estimates (95 confidence interval) were 76 (67-83) and 52 (43-61), respectively, with too few events to assess differences by study group.Conclusions: High immune response rates for this multipeptide vaccine were achieved, but CD8+ and CD4+ T-cell responses were lower when administered with GM-CSF. These data challenge the value of local GM-CSF as a vaccine adjuvant in humans. (Clin Cancer Res 2009;15(22):703644)