Sorafenib and Docetaxel in Patients With Prostate Cancer That Did Not Respond to Previous Hormone Therapy

RATIONALE: Sorafenib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as docetaxel, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving sorafenib together with docetaxel may kill more tumor cells. PURPOSE: This phase II trial is studying giving sorafenib together with docetaxel to see how well it works in treating patients with metastatic androgen-independent prostate cancer.

OBJECTIVES: Primary * To determine the proportion of patients achieving a 50% reduction in serum PSA from baseline in patients with androgen-independent prostate cancer (AIPC) receiving sorafenib tosylate and docetaxel. Secondary * To estimate the progression-free survival of patients with AIPC. * To quantify the number and percent of patients who have stable disease at 6 months of therapy (failure to progress). * To estimate median time to progression for all patients. * To estimate the objective response rate of patients with AIPC treated with this regimen. * To measure the percentage of patients surviving at 2 years. * To determine the toxicities and estimate toxicity rates for patients treated with this regimen. * To measure changes in tumor vasculature in response to therapy in selected patients with dynamic contrast-enhanced MRI (DCE-MRI) and correlate primary and secondary objectives to these measurement changes. * To measure changes in serum HMGB1 in response to therapy and correlate primary and secondary objectives with these changes. * To measure changes in serum cathepsin D in response to therapy and correlate primary and secondary objectives with these changes. OUTLINE: Patients receive oral sorafenib tosylate twice daily on days 2-19 and docetaxel IV on day 1. Treatment repeats every 21 days for up to 10 courses. Patients then receive oral sorafenib tosylate alone twice daily on days 1-19 with treatment repeating every 21 days in the absence of disease progression or unacceptable toxicity. Patients undergo blood collection periodically to measure serum HMGB1 and cathepsin D levels before and after therapy.