Sipuleucel-T With or Without Radiation Therapy in Treating Patients With Hormone-Resistant Metastatic Prostate Cancer

PRIMARY OBJECTIVES: I. To assess the feasibility, based on percent able or willing to receive all three infusions of sipuleucel-T immunotherapy, when combining sipuleucel-T with radiation therapy to a single site of metastasis delivered one week prior to beginning of sipuleucel-T therapy. SECONDARY OBJECTIVES: I. To assess the effect of radiation therapy to single metastasis on immune response (antibody and T-cell proliferation to prostate acid phosphate \[PAP\] and fusion protein PA2024) generated by sipuleucel-T immunotherapy. II. To assess the effect of external beam radiotherapy to single metastasis on prostate specific antigen (PSA) response to therapy with sipuleucel-T. III. To assess the effect of external beam radiotherapy to single metastasis on radiographic response rate to therapy with sipuleucel-T. IV. To assess the time from the onset of therapy with sipuleucel-T +/- radiation to the need for subsequent therapy for prostate cancer. V. To assess the toxicity associated with sipuleucel-T +/- radiation. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM A: Patients receive sipuleucel-T intravenously (IV) over 60 minutes days 22, 36, and 50. ARM B: Patients undergo external beam radiation therapy in weeks 1-2. Patients also receive sipuleucel-T as in Arm A. In both arms, treatment continues in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up until week 60.