The purpose of this is to test the safety and effectiveness of an investigational chemotherapy agent in patients with persistent or recurrent endometrial cancer.

Patients will be enrolled in the study after all study-specific entry criteria are met and informed consent is obtained. Patients will be required to attend regular clinic visits to receive study medication and have their status monitored. They will also be required to have radiologic tumor assessments performed at multiple times throughout the study. A detailed explanation can be provided by the Investigator conducting this study. Trabectedin 1.3 mg/m2 will be given every 21 days to patients intravenously (i.v). over a 3-hour period via a central venous catheter (referred to as a "central line") which is a tube (ie, catheter) placed into a large vein that is used to administer medications. Dexamethasone 4 mg will be given orally (p.o.) the day before trabectedin and dexamethasone 20 mg will be given i.v. 30 minutes before trabectedin. Dexamethasone 4 mg p.o. will be given for 2 days following trabectedin administration.

Inclusion Criteria:

• Diagnosis of advanced or metastatic endometrial carcinoma
• Progressive disease after 1 cytotoxic chemotherapy regimen given for advanced/metastatic disease
• At least one measureable tumor lesion
• Adequate bone marrow, hepatic and renal function
• Performance status ECOG 0 or 1

Exclusion Criteria:

• Prior exposure to trabectedin
• Known hypersensitivity to dexamethasone or to any of the components of trabectedin
• Less than 4 weeks since last radiation therapy or since last dose of hormonal therapy, biological therapy, therapy with any investigational agent, or chemotherapy
• History of another neoplastic disease unless in remission for more than 5 years
• Known metastases (spread) of cancer to the central nervous system or other serious illness as specified in the protocol
• Current pregnancy, lactation, or childbearing potential without adequate method of contraception.