IC50: 0.1 nM (MX-1 cells), 1.5 nM (MCF7 cells) and 3.7 nM (MCF7/DXR cells)
Reactive oxygen species (ROS)
Apoptosis

Trabectedin (ET-743; 10 nM; 24-72 hours; MCF7 cells) treatment cells accumulate in late S to G2 phase.
Trabectedin (Ecteinascidin 743) inhibits cell growth of MX-1, MCF7 and MCF7/DXR cells with IC ₅₀ values of 0.1 nM, 1.5 nM and 3.7 nM, respectively.
Trabectedin induces cytotoxicity and apoptosis in both breast cancer cells in a time and concentration-dependent manner. The expression levels of the death receptor pathway molecules, TRAIL-R1/DR4, TRAIL-R2/DR5, FAS/TNFRSF6, TNF RI/TNFRSF1A, and FADD are significantly increased by 2.6-, 3.1-, 1.7-, 11.2- and 4.0-fold by Trabectedin treatment in MCF-7 cells. In MDA-MB-453 cells, the mitochondrial pathway related pro-apoptotic proteins Bax, Bad, Cytochrome c, Smac/DIABLO, and Cleaved Caspase-3 expressions are induced by 4.2-, 3.6-, 4.8-, 4.5-, and 4.4-fold, and the expression levels of anti-apoptotic proteins Bcl-2 and Bcl-XL are reduced by 4.8- and 5.2-fold in MDA-MB-453 cells.
In vitro treatment with noncytotoxic concentrations of Trabectedin selectively inhibits the production of CCL2, CXCL8, IL-6, VEGF, and PTX3 by myxoid liposarcoma (MLS) primary tumor cultures and/or cell lines.

Trabectedin (ET-743; 30-50 μg/kg; intravenous injection; every three days; female athymic nude mice) treatment increases the antitumor effects in nude mice bearing MX-1 mammary carcinoma xenografts without increasing toxicity.
A xenograft mouse model of human myxoid liposarcoma (MLS) shows marked reduction of CCL2, CXCL8, CD68+ infiltrating macrophages, CD31+ tumor vessels, and partial decrease of PTX3 after Trabectedin treatment.