Inclusion Criteria:

- Male subjects, aged >/= 18 years

- Subjects with histologically or cytologically proven advanced castration-resistant
prostate cancer (CRPC)

- Who failed at least 1 taxane regimen and are refractory to abiraterone therapy
OR

- Who have actively refused any treatment which would be regarded standard

- Subjects should have undergone bilateral orchiectomy or should be on continuous
androgen deprivation therapy with a gonadotropin releasing hormone agonist or
antagonist and should have stopped any anti-androgen therapy for at least 4 weeks
before inclusion in the study.

- Total serum testosterone should be less than 50 ng/ml or 1.7 nmol/L

- Evidence of progressive disease, defined as one or more (Prostate Cancer Working
Group 2 (PCWG2) criteria):

- PSA level of at least 2 ng/ml that has risen on at least 2 successive occasions at
least 1 week apart

- Nodal (in lymph nodes >/= 2cm) or visceral progression as defined by Response
Evaluation Criteria in Solid Tumors (RECIST)

- Appearance of one more new lesions in bone scan

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2

- Life expectancy of at least 3 months

Exclusion Criteria:

- Any anticancer therapy or immunotherapy within 4 weeks of start of first dose

- Confirmed history or current autoimmune disease or other diseases resulting in
permanent immunosuppression or requiring permanent immunosuppressive therapy

- Prior radiotherapy (local palliative radiotherapy is permitted)

- History of allergic reactions to monoclonal antibody therapy

- History of clinical significant cardiac disease: including unstable angina, acute
myocardial infarction within 6 months prior to first study treatment, congestive
heart failure ≥New York Heart Association (NYHA) Class III), and arrhythmia
requiring therapy except for beta-blockers and digoxin or uncontrolled hypertension,
despite optimal medical management

- Clinically relevant findings in the electrocardiogram (ECG) such as a second- or
third-degree AV block, prolongation of the QRS complex over 120 msec or of the QT
interval corrected for heart rate (QTc)-interval over 450 msec

- History or current evidence of human immunodeficiency virus (HIV) infection or
hepatitis B or C

- Chronic high dose systemic corticosteroid therapy longer than 2 months (low dose
systemic corticosteroid therapy e.g. 10 mg prednisone / day is acceptable) or any
other immunosuppressive therapies or stem-cell transplantation

- Seizure disorder requiring therapy (such as steroids or anti-epileptics)

- Subjects unable to inject the study drug subcutaneously