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

PRIMARY OBJECTIVES: I. To determine whether tasquinimod augments immune response to sipuleucel-T. SECONDARY OBJECTIVES: I. To assess the safety and tolerability of the combination of sipuleucel-T and tasquinimod in patients with castration-resistant metastatic prostate cancer. II. To obtain preliminary evidence of the clinical benefit of the combination of sipuleucel-T and tasquinimod; to include changes in prostate specific antigen (PSA) over time, and duration of progression-free survival/overall survival. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive sipuleucel-T intravenously (IV) over 60 minutes on day 4. Treatment repeats every 2 weeks for 3 courses in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive tasquinimod orally (PO) once daily (QD) beginning on day -14 and sipuleucel-T IV over 60 minutes on day 4. Treatment repeats every 2 weeks for 3 courses in the absence of disease progression or unacceptable toxicity. Patients continue on tasquinimod treatment after day 42 until disease progression. After completion of study treatment, patients are followed up every 3 months for up to 3 years.