Trabectedin (ET-743) is a marine alkaloid isolated from the Caribbean tunicate Ecteinascidia turbinata. Trabectedin was approved for the treatment of liposarcoma or leiomyosarcoma (USA and Europe) and ovarian cancer (only in Europe). Trabectedin exerts its anti-cancer action by binding guanine residues in the minor groove of DNA. The binding prevents DNA from interacting with transcription factors and the reparation system and results in perturbation of the cell cycle and eventual cell death.