Inclusion Criteria:

• Signed informed consent in accordance with GCP and local regulatory requirements prior to trial participation
• Male and age ≥ 18 years
• Histologically confirmed diagnosis of adenocarcinoma of the prostate, Gleason Score available
• Patients must have been treated with hormonal therapy and may have been treated with surgery and/ or radiation therapy
• Progressive disease as defined by hormone-refractoriness and rise in PSA:

Hormone-refractoriness: Defined by a rise in PSA and/or RECIST-based progression of evaluable lesions, and/or increased number of hotspots on a bone scan, while the patient has a castrated level of testosterone. This castrated level may have been obtained by orchiectomy, or LH-RH analog ± antiandrogen. Antiandrogen must be discontinued for at least 4 weeks before study entry to exclude a withdrawal effect.

Rise in PSA: Defined by a rise in PSA levels at three consecutive time points (PSA rise over nadir, separated by > 1 week)

• Presence of metastatic disease is acceptable
• ECOG performance status of 0 to 1
• Life expectancy > 12 months as assessed by the investigator
• Adequate organ function :

Bone marrow function: Hemoglobin ≥ 10 g/ dL; Leukocytes ≥ 3000/ µL; Lymphocytes ≥ 1000/ µL; Absolute neutrophil count ≥ 1500/ µL; Platelet count ≥ 100000/ µL Hepatic: AST and ALT ≤ 2.5 times upper limit of normal (ULN); Bilirubin ≤ 1.5 ULN Renal: Creatinine ≤ 1.5 mg/ dL or creatinine clearance ≥ 60mL/ min

• Concomitant LH-RH therapy continuation is acceptable
• May have had local palliative radiotherapy for bone metastasis involving less than 25% of bone marrow
• Patients requiring bisphosphonates at the time of registration into the trial are eligible (therapy initiated at least 28 days prior to first study treatment administration) and must be continued at a constant level during the study period.
• Patients of child-producing potential must agree to use contraception while enrolled in the study and for one month after the last immunization.

Exclusion Criteria:

• Other histologic type of prostate cancer (transitional cell, small cell or squamous cell cancer)
• Symptomatic brain metastasis or leptomeningeal involvement
• Patients receiving systemic anticancer therapy
• Symptomatic congestive heart failure (NYHA 3 and 4); unstable angina pectoris; significant cardiac arrhythmia
• Pulmonary disease causing dyspnea or fatigue during normal activity
• History of seizures, encephalitis or multiple sclerosis
• Inflammatory bowel disease e.g. Crohn's disease or ulcerative colitis; active diverticulitis
• Documented history of active autoimmune disorders requiring systemic immunosuppressive therapy, (e.g. sarcoidosis, lupus erythematosus, rheumatoid arthritis, glomerulonephritis or systemic vasculitis), excepting autoimmune thyroiditis with only thyroid hormone replacement and stable disease > 1 year
• Primary or secondary immune deficiency
• History of allergy requiring medication
• Active drug abuse or chronic alcoholism
• Clinically significant active infections
• Seropositive for HIV, HBV or HCV
• History of other malignancies over the last 5 years (except basal cell carcinoma of the skin or carcinoma in situ of the bladder)
• Uncontrolled medical condition considered as high risk for the treatment with an investigational drug including unstable diabetes mellitus, vena-cava-syndrome, known ascites and/or pleural effusion, symptomatic pleural effusion treated by puncture
• Renal insufficiency requiring dialysis
• Patients being committed to an institution by virtue of an order issued either by the judicial or the administrative authorities