6.6. Breast Cancer. Since HER-2/neu (HER2) oncogenic protein is a tumor antigen in patients with breast and ovarian cancer, several vaccine strategies have been developed and are being evaluated for safety and immunogenicity in phases I and II clinical trials (ClinicalTrials.gov). Patients whose tumors overexpress the antigen have both detectable antibody and T-cell immunity directed against HER2. Likewise preclinical studies suggest that the HER2 protein, particularly the intracellular domain (ICD), is a tumor rejection antigen [148] . Salazar and colleagues are studying the immune response in patients overexpressessing HER2 epitope who have undergone vaccine therapy in a heterologous prime-boost regimen (ClinicalTrials.gov identifier: NCT00363012). After vaccination with a plasmid encoding HER2 ICD in patients with advanced stage HER2 overexpressing breast and ovarian cancers patients receive HER2 ICD protein treatment intradermally at 6 months postvaccination with the pNGVL3-hICD vaccine. The injection site is biopsied and examined for infiltrating T-cell and antigen-presenting cell populations and blood samples are examined for the presence of memory markers to demonstrate the development of HER2 ICD memory immunity.