Purpose: E4697 was a multicenter intergroup randomized placebo-controlled phase III trial of adjuvant
GM-CSF and/or a multiepitope
melanoma peptide vaccine for patients with completely resected, high-risk stage III/IV
melanoma.Experimental Design: A total of 815 patients were enrolled from December 1999 to October 2006 into this six-arm study.
GM-CSF was chosen to promote the numbers and functions of dendritic cells (DC). The
melanoma antigen peptide vaccine (Tyrosinase368-376 (370D), gp100209-217 (210M), MART-127-35) in
montanide was designed to promote
melanoma-specific CD8+ T-cell responses.Results: Although the overall RFS and OS were not significantly improved with the
vaccine or
GM-CSF when compared with placebo, immunomodulatory effects were observed in peripheral blood and served as important correlates to this therapeutic study. Peripheral blood was examined to evaluate the impact of
GM-CSF and/or the
peptide vaccine on peripheral blood immunity and to investigate potential predictive or prognostic
biomarkers. A total of 11.3% of unvaccinated patients and 27.1% of vaccinated patients developed
peptide-specific CD8+ T-cell responses. HLA-A2+ patients who had any
peptide-specific CD8+ T-cell response at day +43 tended to have poorer OS in univariate analysis. Patients receiving
GM-CSF had significant reduction in percentages of circulating myeloid dendritic cells (mDC) and plasmacytoid DC (pDC) at day +43. In a subset of patients who received
GM-CSF, circulating myeloid-derived suppressor cells (MDSC), and anti-
GM-CSF-
neutralizing antibodies (Nabs) were also modulated. The majority of patients developed anti-
GM-CSF Nabs, which correlated with improved RFS and OS.Conclusions: The assessment of cellular and humoral responses identified counterintuitive immune system changes correlating with clinical outcome. Clin
Cancer Res; 23(17); 5034-43. ©2017 AACR.