3.2 Exclusion Criteria 3.2.1 Prior chemotherapy for castration resistant prostate cancer . Neoadjuvant chemotherapy and chemotherapy given for hormone sensitive prostate cancer are allowed. 3.2.2 Prior investigational immunotherapy 3.2.3 Prostate cancer pain requiring regularly scheduled narcotics 3.2.4 Pathologic long -bone fractures, imminent pathologic long -bone fracture (cortical erosion on radiography > 50%) or spinal cord compression 3.2.5 Current treatment with systemic steroid therapy (inhaled/topical steroids are acceptable)  Systemic corticosteroids must be discontinued for at least 30 days prior to first CYT107 injection. 3.2.6 Known central nervous system metastases 3.2.7 Documented cirrhosis or documented acute hepatitis Note : A positive hepatitis B serology indicative of previous immunization (i.e., HBsAb positive and HBcAb negative), or a fully resolved acute HBV infection is not an exclusion criterion. NCI Protocol #: CITN12 -03 Version Date: July 26, 2017 18 3.2.8 History of severe asthma, as defined by prior or current use of systemic corticosteroids for disease control, with the exception of physiological replacement doses of corti sone acetate or equivalent, as defined by a dose of 10 mg or less 3.2.9 Medical or psychiatric illness that would, in the opinion of the investigator, preclude participation in the study or the ability of patients to provide informed consent for themselves 3.2.10 Cardiovascular disease that meets one of the following: congestive heart failure (New York Heart Association Class III or IV), active angina pectoris, or recent myocardial infarction (within the last 6 months) 3.2.11 Concurrent or prior malignancy except for the f ollowing:  Adequately treated basal or squamous cell skin cancer  Adequately treated stage I or II cancer from which the patient is currently in complete remission  Any other cancer from which the patient has been disease -free for 5 years 3.2.12 Known HIV or other history of immunodeficiency disorder. HIV -positive patients on combination antiretroviral therapy are ineligible because of the potential for pharmacokinetic interaction with CYT107. Other trials are examining the effect of CYT107 in pat ients with HIV infection. 3.2.13 Prisoners or subjects who are compulsorily detained (involuntarily incarcerated) for treatment of either a psychiatric or medical (e.g. infectious) illness 3.2.14 Any underlying medical or psychiatric condition, which in the opinion o f the investigator will make the administration of CYT107 hazardous or obscure the interpretation of AEs, such as a condition associated with frequent diarrhea 3.2.15 History of allergic reactions attributed to compounds of similar chemical or biologic composit ion to CYT107 3.2.16 Patients who have received prior immunosuppressive therapy within 30 days prior to enrollment 3.2.17 Active (as defined by requiring immunosuppressive therapy) or history of clinically significant autoimmune disease (as defined by previously requi ring immunosuppressive therapy) 3.2.18 Patients who have received hepatotoxic drugs less than 7 days prior to enrollment 3.2.19 Patients who have received prior biologic agents less than 30 days prior to enrollment NCI Protocol #: CITN12 -03 Version Date: July 26, 2017 19 3.2.20 Uncontrolled intercurrent illness including, but no t limited to, ongoing or active infection, congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements 3.2.21 Patients who have a history of any hematopoieti c malignancy 3.2.22 History of pulmonary disease such as emphysema or COPD, (FEV > 60% of predicted for height and age required in patients with prolonged smoking history or symptoms o f respiratory dysfunction). 3.3 Inclusion of Minorities Men of all races and ethnic groups are eligible for this trial.