Inclusion criteria:

• Provide written informed consent.
• Previous diagnosis of HER2/neu-positive breast cancer.
• Stage II with 4 or more positive nodes, or Stage III in remission.
• Have had standard treatment for their cancer, including lymph node dissection and at least one course of standard adjuvant treatment with or without local-regional breast irradiation.
• Free of recurrent breast cancer disease.
• Current chest X-ray showing no evidence of disease.
• Completed at least one course of standard adjuvant treatment within 2 years of study entry.
• Life expectancy of at least 12 months.

Exclusion criteria:

• Surgery or chemotherapy treatment within 8 weeks of study enrollment.
• Radiotherapy within 12 weeks of study enrollment.
• Use of other experimental agents during study.
• Use of investigational or commercial agents or therapies intended to treat the malignancy during the study or within 1 month prior to first study vaccination.
• Patients younger than 40 years of age must be sterile or incapable of childbearing.
• Heart problems or uncontrolled hypertension, bleeding or coagulation disorders, auto-immune disorders, or psychiatric illness or addictive disorders.
• Known to be HIV positive.
• Past or current treatment with drug Herceptin.
• Pregnant or breastfeeding.
• Any uncontrolled illness that would preclude the study.