Booster inoculations will consist of the same intervention as each patient received during their regular inoculation series. Patients enrolled to the E75/GM-CSF vaccine arm of the trial will receive four consecutive booster inoculations of 1000 mcg E75 peptide + 250 mcg GM-CSF, and patients enrolled to the GM-CSF alone arm will receive four consecutive booster inoculations of 250 mcg GM-CSF only. For patients with childbearing potential, a urine pregnancy test will be performed before each booster inoculation.