Topoisomerase-II Inhibitor Racemic XK469

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** The racemic form of a synthetic quinoxaline phenoxypropionic acid derivative with antineoplastic properties. XK469R selectively inhibits topoisomerase II by stabilizing the enzyme-DNA intermediates in which topoisomerase subunits are covalently linked to DNA through 5-phosphotyrosyl linkages, thereby interfering with DNA repair and replication, RNA and protein synthesis. This agent possesses unusual solid tumor selectivity and activity against multidrug-resistant cancer cells. XK469R is more water soluble and active than the pure isomers, R(+)XK469 and S(-)XK469. (NCI05)

**Synonyms:** - Propanoic acid, 2-[4-[(7-chloro-2-quinoxalinyl)oxy]-phenoxy]-, (+ /-)- - XK469 Racemic - XK469R