Randomized Phase Ii Clinical Trial Of The Anti-Her2 (Gp2) Vaccine To Prevent Recurrence In High-Risk Breast Cancer Patients: A Planned Interim Analysis.

3005 Background: A prospective, randomized, multi-center, placebo-controlled, single-blinded, phase II trial was designed to evaluate the safety and clinical efficacy of GP2, a HER2-derived peptide vaccine, in breast cancer patients. Methods: Clinically disease-free, node-positive or high-risk node-negative patients (pts) with any level of HER2 expression were enrolled after standard of care therapy. HLA-A2+ pts were randomized to receive GP2 + GM-CSF (VG) or GM-CSF alone (CG). HLA A2- controls from a parallel arm of the study were also eligible for evaluation, the extended CG (ECG). Pts receive 6 monthly intradermal inoculations (R0-R6) during the primary vaccine series followed by four boosters every 6 mos. Immune responses (IR) were measured by delayed type hypersensitivity (DTH) at R0 and R6. This planned interim analysis was performed at 24 months median follow-up. Results: We have currently enrolled 172 pts (46, VG; 43, CG; 83 extended CG). There are no differences between groups with respect to age...