Melanoma GVAX administered intradermally increases systemic GM-CSF levels in a dose-dependent manner. a Serum GM-CSF concentrations measured 2 days after the first administration of Melanoma GVAX were significantly higher in patients receiving a dose of 2E8 cells (Cohorts B and C, mean 19.8 ± 2.72) compared to 5E7 cells (Cohort A, mean 4.8 ± 1.5). There was no significant difference between patients receiving high-dose vaccine in Cohorts B (no CPM) versus C (with CPM) (not shown). All patients had detectable serum GM-CSF after the first vaccination (detection limit 1 pg/ml). b Serum GM-CSF concentrations were significantly lower 2 days after the fourth vaccine (6.8 ± 1.5) compared to the first vaccine (17.5 ± 2.6). Bars depict the mean ± SEM; p values from 2-sided Mann–Whitney U test (a) or paired Wilcoxon signed-rank test (b). C treatment cycle, D treatment day. Pre-vaccine sera from Cohort C were collected on D0 prior to CPM administration, and from Cohorts A and B, on D1 prior to vaccine administration.