Inclusion criteria 1. Subjects must have either Stage IV breast or ovarian cancer in remission or with stable disease on trastuzumab monotherapy . 2. HER2 overexpression by immunohistocytochemistry (IHC) of 2+ or 3+, in the primary tumor or metastasis. If overexpression is 2+ by IHC, then patients must have HER2 gene amplification documented by FISH. 3. Subjects must be HLA -A2 positive. 4. Eligible subje cts must have completed appropriate treatment for their primary disease and be off cytotoxic chemotherapy and any immunosuppressive agents such as systemic steroids for at least 30 days prior to enrollment. Patients should continue trastuzumab monotherapy throughout the course of this protocol. Concurrent hormonal and biphosphanate therapies are allowed. 5. Subjects must have an ECOG Performance Status Score = 0 or 1 (Appendix A) 6. Male subjects must agree to contraceptive use during the study period (7 months) and non- menopausal female subjects must agree to contraception for the remainder of their childbearing years. (HER2 is overexpressed in normal fetal tissues. Therefore, induction of long -term immunity to overexpressed HER2 could affect the via bility of a future fetus.) 7. Subjects must have a hematocrit > 30, a platelet count > 100,000, and a WBC > 3000/µl. Laboratory tests should be performed within 60 days of enrollment. 8.