Edotecarin is a potent inhibitor of topoisomerase I that can induces single-strand DNA cleavage, with IC₅₀ of 50 nM. IC50 & Target: IC50: 50 nM (topoisomerase I)^[1] In Vitro: In the presence of human colon cancer cells labeled with ³Hthymidine, edotecarin (0.6 μmol/L) increases the formation of DNA-protein complexes in a time-dependent manner^[1]. In Vivo: Edotecarin produces an 83% increase in survival in mice bearing intracranial D-456MG glioma and shows a strong antimetastatic effect^[1]. Edotecarin results in tumor growth delays ranging from 10.45 days at the lowest dose (3 mg/kg) to 24.83 days at the highest (100 mg/kg). Combination treatment of edotecarin plus irinotecan improves antitumor activity in vivo compared with either agent alone^[2].