A Study of ET-743 (Trabectedin) in Patients With Advanced Breast 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. Patients will also be required to have radiologic tumor assessments performed at multiple times throughout the study. A detailed explanation can be provided by the study physician (Investigator) conducting this study. Trabectedin 580 mcg/m2 once weekly for 3 consecutive weeks (Treatment A) or 1,300 mcg/m2 once every 21 days (Treatment B) will be given to patients as a 3-hour intravenous (i.v). infusion via a central venous catheter which is a tube placed into a large vein that is used to administer medications. All patients will be given dexamethasone 10 mg i.v. 30 minutes before each trabectedin infusion. Patients may receive multiple cycles of trabectedin in the absence of disease progression.

Inclusion criteria

• Diagnosis of advanced breast cancer
• Prior therapy with anthracycline and taxane (2 types of chemotherapy drugs)
• At least one measureable tumor lesion
• Adequate bone marrow, hepatic and renal function
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1

Exclusion criteria

• Known hypersensitivity to any components of the i.v. formulation of ET-743 or dexamethasone
• Pregnant or lactating women
• Known metastases (spread) of cancer to the central nervous system
• History of another neoplastic disease unless in remission for five years or more.