A drug used to treat liposarcoma and leiomyosarcoma (types of soft tissue sarcoma) that cannot be removed by surgery or have spread to other parts of the body. It is used in patients who were treated with other anticancer drugs. It is also being studied in the treatment of other types of cancer. Trabectedin may kill cancer cells by damaging their DNA and stopping them from dividing. It is a type of alkylating agent. Also called ecteinascidin 743, ET-743, and Yondelis. OR A tetrahydroisoquinoline alkaloid isolated from the marine tunicate Ecteinascidia turbinate with potential antineoplastic activity. Binding to the minor groove of DNA, trabectedin inteferes with the transcription-coupled nucleotide excision repair machinery to induce lethal DNA strand breaks.and blocks the cell cycle in the G2 phase.