Trial of RNActive®-Derived Prostate Cancer Vaccine in Metastatic Castrate-refractory Prostate Cancer

Key Inclusion Criteria: 1. Male, age ≥18 years 2. Histologically confirmed castrate refractory metastatic adenocarcinoma of the prostate with progressive disease after surgical castration or during androgen suppression therapy including a GNRH agonist or antagonist and after at least 1 additional anti-hormonal manipulation; and serum testosterone level of \< 50 ng/dL or \< 1.7 nmol/L Progression will be confirmed either * radiologically or * by 2 consecutive rises of PSA, measured at least 1 week apart, resulting at least in a 50% increase over the nadir and a PSA \> 2 ng/mL. * An antiandrogen withdrawal response must have been excluded after discontinuation of antiandrogen therapy for at least 6 weeks. 3. Metastatic disease confirmed by imaging 4. ECOG performance status 0 or 1 Key Exclusion Criteria: 1. Previous immunotherapy for PCA (e.g. sipuleucel-T \[Provenge®\], experimental cancer vaccines or ipilimumab \[Yervoy®\]). 2. Treatment with any investigational anticancer agents within 4 weeks prior to first dose of study drug 3. Systemic treatment with immunosuppressive agents 4. Active skin disease (atopic eczema, psoriasis) in the areas for vaccine injection (upper arms or thighs) preventing the administration of i.d. injections into areas of healthy skin. 5. History of or current autoimmune disorders 6. Primary or secondary immune deficiency. 7. Seropositive for human immunodeficiency virus, hepatitis B virus (except after hepatitis B vaccination) or hepatitis C virus infection. 8. Symptomatic congestive heart failure (New York Heart Association 3 or 4), unstable angina pectoris or myocardial infarction, significant cardiac arrhythmia, history of stroke or transient ischemic attack, all within 6 months prior to enrolment or severe hypertension according to WHO criteria or uncontrolled hypertension at the time of enrolment (systolic blood pressure ≥ 180 mm Hg)´ 9. Previous chemotherapy for metastatic PCA. 10. Previous anti-hormonal treatment with abiraterone or any other investigational anti-hormonal treatment. 11. Cancer-related pain requiring opioid narcotics within 28 days before enrolment or an average pain score of \> 3 on a visual analogue scale. 12. Presence of visceral metastases. 13. History of other malignancies other than PCA over the last 5 years (except basal cell carcinoma of the skin).