Concurrent vs. Sequential Sipuleucel-T & Abiraterone Treatment in Men With Metastatic Castrate Resistant Prostate Cancer

Inclusion Criteria: * histologically documented prostate cancer confirmed by a pathology report from prostate biopsy or radical prostatectomy specimen * metastatic status as evidenced by imaging obtained \</= 56 days prior to registration demonstrating bone metastasis or lymph node metastasis * castrate resistant prostate cancer: castrate levels of testosterone (\</= 50 ng/dL); evidence of disease progression concomitant with surgical or medical castration * serum PSA \>/= 2.0 ng/mL * castrate levels of testosterone (\</= 50 ng/dL) achieved via medical or surgical castration * baseline Eastern Cooperative Oncology Group (ECOG) performance status of \</= 1 * systolic blood pressure (BP) \</= 140 mm Hg and diastolic BP \</= 90 mm Hg at screening * adequate baseline hematologic, renal, and liver functions * must live in a permanent residence within a comfortable driving distance (round trip within one day) of the clinical trial site Exclusion Criteria: * the presence of known lung, liver, or brain metastases, malignant pleural effusions, or malignant ascites * New York Heart Association Class III or IV heart failure * any medical condition that may be compromised by increases in blood pressure, hypokalemia, or fluid retention * Child-Pugh Class B or C hepatic insufficiency * spinal cord compression, imminent long bone fracture, or any other condition likely to require radiation therapy and/or steroids for pain control * known adrenalcortical insufficiency * any medical contraindications to receiving prednisone * prior treatment with sipuleucel-T * previous treatment with abiraterone acetate (Zytiga(R)) or ipilimumab (Yervoy(TM)) * a requirement for systemic immunosuppressive therapy for any reason. Use of inhaled, intra-nasal, intra-articular, and topical steroids was allowed. * treatment with any investigational vaccine or immunotherapy * treatment with any chemotherapy prior to registration. * a history of stage III or greater cancer, excluding prostate cancer. Basal or squamous cell skin cancers must have been adequately treated and the subject must be disease-free at the time of registration. Subjects with a history of stage I or II cancer must have been adequately treated and been disease-free for ≥ 3 years at the time of registration. * myocardial infarction or ventricular or atrial arrhythmia within 6 months prior to registration * ongoing anti-androgen withdrawal response. * systemic steroid use within ≤ 60 days of registration * treatment with denosumab (Xgeva(R) or Prolia (R)) within ≤ 3 months prior to registration * positive test for human immunodeficiency virus (HIV) or human T cell lymphotrophic virus (HTLV) infections. Subjects with a positive test for hepatitis B or hepatitis C were allowed provided they meet the liver function test (LFT) criteria and have no signs of acute infection or active disease. * treatment with any of the following medications or interventions within 28 days prior to registration: external beam radiation or major surgery requiring general anesthetic; saw palmetto; megestrol acetate (Megace(R)), diethylstilbestrol, and cyproterone; 5-alpha-reductase inhibitors (e.g. finasteride \[Proscar(R)\], dutasteride \[Avodart(R)\]); steroidal anti-androgen therapy; any other systemic therapy for prostate cancer, except for medical castration; treatment with any other investigational product for prostate cancer; substrates of CYP2D6 (e.g. including but not limited to thioridazine); inhibitors of CYP3A4 (e.g. including but not limited to ketoconazole, itraconazole, clarithromycin, nefazodone, telithromycin, and voriconazole); inducers of CYP3A4 (e.g. including but not limited to phenytoin, carbamazepine, rifampin, rifapentine, and phenobarbital) * a requirement for treatment with opioid analgesics within 21 days prior to registration * an active infection or infection requiring parenteral antibiotic therapy or causing fever within 7 days of registration * any medical intervention, or other condition, or any other circumstance that, in the opinion of the Investigator or the Dendreon Medical Monitor, could compromise adherence with study requirements or otherwise compromise the study's objectives