Apatinib in Combination With Stereotactic Body Radiation Therapy (SBRT) Treatment for Symptomatic Metastatic Prostate Cancer

Inclusion Criteria: * Histologic diagnosis of adenocarcinoma of the prostate * Metastatic and symptomatic prostate cancer (positive bone scan or measurable disease) * Patients must stop using any herbal product known to decrease PSA levels (eg., saw palmetto and PC-SPES) or any systemic or topical corticosteroid at least 4 weeks prior to screening. Progressive disease must be documented after discontinuation of these products. * Progressive disease after androgen deprivation (or hormone therapy). For patients with measurable disease, progression will be defined by Response Evaluation Criteria in Solid Tumors (RECIST) criteria. For patients with progression in, or without any measurable disease, a positive bone scan and elevated PSA will be required. * Patients receiving bisphosphate therapy must have been on stable doses for at least 4 weeks with stable symptoms prior to enrollment. * No prior chemotherapy or immunotherapy (tumor vaccine, cytokine, or growth factor given to control prostate cancer). * Prior radiation therapy completed at least 4 weeks prior to enrollment. No prior radiopharmaceuticals (strontium, samarium) within 8 weeks prior to enrollment. Exclusion Criteria: * History of severe hypersensitivity reactions to drugs formulated with polysorbate 80. * Patients with active autoimmune disease or a history of autoimmune disease that required systemic steroids or immunosuppressive medications, except for patients with vitiligo. * Prior therapy with any anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA-4) antibody. * Active infection requiring therapy. * Concurrent medical condition requiring the use of systemic or topical corticosteroids; systemic or topical corticosteroids must be discontinued at least 4 weeks prior to enrollment. The use of inhaled corticosteroids is acceptable.