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Purpose E75 is an immunogenic peptide from the HER2/neu protein that is highly expressed in breast cancer. We are conducting a clinical trial of an E75 + granulocyte-macrophage colony-stimulating factor vaccine to assess safety, immunologic response, and the prevention of clinical recurrences in patients with disease-free, node-positive breast cancer (NPBC). Patients and Methods Fifty-three patients with NPBC were enrolled and HLA typed. HLA-A2+ patients (n = 24) were vaccinated, and HLA-A2− patients (n = 29) are observed prospectively as clinical controls. Local/systemic toxicities, immunologic responses, and time to recurrence are being measured. Results Only minor toxicities have occurred (one grade 3 [4%]). All patients have demonstrated clonal expansion of E75-specific CD8+T cells that lysed HER2/neu-expressing tumor cells. An optimal dosage and schedule have been established. Patients have developed delayed-type hypersensitivity reactions to E75 postvaccination compared with controls (33 v 7 mm; P < .01). HLA-A2+ patients have been found to have larger, more poorly differentiated, and more hormonally insensitive tumors compared to HLA-A2− patients. Despite this, the only two deaths have occurred in the control group. The disease-free survival in the vaccinated group is 85.7% compared to 59.8% in the controls at 22 months' median follow-up with a recurrence rate of 8% compared to 21%, respectively (P < .19). Median time to recurrence in the vaccinated patients was prolonged (11 v 8 months), and recurrence correlated with a weak delayed-type hypersensitivity response. Conclusion This HER2/neu (E75) vaccine is safe and effective in eliciting a peptide-specific immune response in vivo. Induced HER2/neu immunity seems to reduce the recurrence rate in patients with NPBC.

3067 Background: E75 is an immunogenic peptide from the HER2/neu protein that is expressed in prostate cancer. High-risk prostate cancer (HRPC) patients demonstrating various levels of HER2/neu expression were vaccinated with E75 peptide + GM-CSF to prevent post-prostatectomy prostate-specific antigen (PSA) and clinical recurrences. Methods: 40 HRPC patients were prospectively identified using the validated Center for Prostate Disease Research (CPDR)/CaPSURE high-risk equation and enrolled. HLA-A2+ patients (n=21) were vaccinated (V), and HLA-A2- patients (n=19) were followed as clinical controls (C). HER2/neu over-expressors (OE) were defined as IHC 3+ and low-expressors (LE) as IHC 0–2+. All patients were assessed for clinico-pathologic factors, PSA recurrence (≥0.2ng/ml), clinical recurrence and survival. Results: Comparing the V and C groups, there were no statistical differences in clinico-pathologic factors; however, the V group had larger tumors (≥T3b-T3c: 35% vs. 18%), higher postop Gleason scores...