Increased melanoma peptide-specific reactivity generated in one patient over time on treatment with Melanoma GVAX. This patient in Cohort A was HLA-A2+ . IFN-g ELISPOT was used to measure the specific reactivity of short-term in vitro stimulated T cell cultures against a pool of melanoma peptides restricted by HLA-A2. Stimulation index = [IFN-g spot forming colonies/1E6 cells stimulated with melanoma peptide pool]/[IFN-g spot forming colonies/1E6 cells stimulated with HBV control peptide]. Trends were similar in two separate assays, showing peak reactivity after two cycles of treatment. C treatment cycle; D treatment day.