The main purpose of this study is to find out what effects (good or bad) trabectedin (ET743) has on men with advanced prostate carcinoma.

• Treatment with trabectedin will be given once a week for three consecutive weeks with one week of no treatment. This four week period constitutes one cycle.
• Trabectedin is given as an infusion through a central venous catheter and is administered over 3 hours.
• On day 1 of each cycle a history, physical exam and blood tests will be performed and trabectedin will be administered.
• On day 8 and day 15 of each cycle blood work will be performed and trabectedin will be administered.
• Patients will continue to receive trabectedin as long as there is no disease progression or unacceptable side effects.
• Scans (CT, MRI or bone) or x-rays may be done while the patient is on the trial at the discretion of the physician.

Inclusion Criteria:

• Histologically confirmed adenocarcinoma of the prostate
• Radiographically documented metastatic disease
• Surgical or chemical castration
• Prostate specific antigen (PSA) > 5 ng/ml
• Castration resistant prostate cancer (CRPC)
• One previous taxane-based chemotherapy regimen
• Eastern Cooperative Group (ECOG) performance status 0,1 or 2
• Neutrophil count > 1,500/ul
• Platelet count > 100,000/ul
• Serum bilirubin < 1.0 x upper limit normal (ULN)
• Serum alkaline phosphatase < 1.5 x ULN
• Asparate aminotransferase/Alanine aminotransferase < 2.5 x ULN
• Albumin > 2.5 g/dl
• Serum creatinine < 1.5 x ULN
• Prior hormonal therapy

Exclusion Criteria:

• Chemotherapy treatment within 4 weeks of study entry
• Patient not employing adequate contraception
• Serious illness or medical conditions, specifically: uncontrolled congestive heart failure or history of myocardial infection or active angina pectoris within 6 months; active infectious process; chronic active liver disease, including chronic hepatitis B, C or cirrhosis
• Current anti-cancer treatment with any non-FDA approved investigational drug