The primary aim of this study is to investigate time to progression in breast cancer patients vaccinated with autologous dendritic cells pulsed with peptides in combination with adjuvant aromatase inhibitor (AI), Thymosin 1 alpha and interleukin-2. The secondary aim is to investigate whether a measurable immune response can be induced, and to evaluate the clinical effect (objective response rate) of the vaccination regime.

Only patients who have tumors \> 5 % positive for p53 by IHC can be referred to this treatment. All patients will receive standard dosage of AI +/- p53-DC vaccination. Patients who express HLA-A2 will also receive DC vaccination. Patients that do not express HLA-A2 will receive only AI and be regarded as controls. The vaccination regime consists of primary 10 intradermal injections of 1-2 weeks interval (q1w x 4 → q2w x 6) with p53 peptide-pulsed dendritic cells, followed by monthly injections until progression; proleukin and Zadaxin are used as vaccine adjuvants. Defined procedures are employed for generation of autologous dendritic cells for clinical application in a classified laboratory. Unmobilized leukapheresis will be used for isolation of large-scale mononuclear cells, and dendritic cells will be generated from monocytes by cytokine stimulation and loaded with p53 peptides. Frozen preparations of dendritic cells will be prepared using automated cryopreservation.Each patient will receive a minimum of 5x10\^6 dendritic cells per treatment supplemented with interleukin-2 6 MIU/m² sc per vaccine and 1.6 mg Thymosin 1 alpha sc x 2/week. Toxicity including autoimmunity will be evaluated using the common Toxicity Criteria (CTC).