Vaccine Therapy in Treating Patients Receiving Trastuzumab For HER2-Positive Stage IIIB-IV Breast Cancer

PRIMARY OBJECTIVES: 1\. To estimate the RFS in patients with HER2 positive locally advanced breast cancer vaccinated with a HER2 ICD peptide-based vaccine. SECONDARY OBJECTIVES: 1. To assess the safety of a HER2 ICD peptide-based vaccine administered concurrently with trastuzumab. 2. To determine the immunogenicity of the HER2 ICD peptide based vaccine when given within one year of initiating standard treatment which includes trastuzumab. 1. To determine the incidence of the development of T cell immunity specific for the HER2 ICD. 2. To determine the incidence of the development of intramolecular epitope spreading. 3. To determine the magnitude of the HER2 ICD specific CD4+ and CD8+ immune response generated with immunization. 3. To assess whether there is an association between RFS and the development of an immune response (HER2 specific T cell immunity and/or the development of intramolecular epitope spreading). OUTLINE: Patients receive HER-2/neu intracellular domain peptide-based vaccine mixed with GM-CSF intradermally (ID) once monthly for 6 months in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up at 1, 4, 8, and 12 months and then annually thereafter for up to 5 years.