A Randomized, Open-label, Phase 2 Trial of Sipuleucel-T With Concurrent Versus Sequential Administration of Abiraterone Acetate Plus Prednisone in Men With Metastatic Castrate Resistant Prostate Cancer (mCRPC)

Inclusion Criteria:

- historically documented prostate cancer confirmed by a pathology report from prostate
biopsy or radical prostatectomy specimen

- metastatic status as evidenced by imaging obtained demonstrating bone metastasis or lymph node metastasis

- castrate resistant prostate cancer: castrate levels of testosterone ( evidence of disease progression concomitant with surgical or medical castration

- serum PSA >/= 2.0 ng/mL

- castrate levels of testosterone ( castration

- baseline ECOG performance status of
- systolic blood pressure (BP)
- adequate baseline hematologic, renal, and liver functions

- must live in a permanent residence within a comfortable driving distance (roundtrip
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 is allowed.

- treatment with any investigational vaccine or immunotherapy

- 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 HIV or HTLV infections. Subjects with a positive test for
hepatitis B or hepatitis C are allowed provided they meet the 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