Blood Samples to Evaluate Immune Response to Provenge® (Sipuleucel-T) inHormone Refractory Metastatic Prostate Cancer Patients

This study is being conducted to assess and monitor immune response in patients with minimally symptomatic or asymptomatic hormone refractory prostate cancer who will be receiving Provenge® (Sipuleucel-T) therapy as part of their standard of care treatment regimen. The trial only involves the collection of additional blood samples for the purposes of monitoring immune response. These samples will be taken at 7 time points before, during and after patients receive Provenge® (Sipuleucel-T). There will be no other study-specific procedures performed (other than the blood draws) nor any use of investigational agents in this study.