Intoplicine is a DNA topoisomerase I and II inhibitor. IC50 & Target: DNA topoisomerase^[1] In Vitro: Activity of Intoplicine (RP60475), a new DNA topoisomerase I and II inhibitor, against human tumor colony-forming units in vitro. Intoplicine (RP60475) is the most active analogue evaluated in the 7H-benzo[e]-pyrido-[4,3-b]-indole series of antineoplastic compounds. Intoplicine exerts its activity through inhibition of DNA topoisomerase I and II^[1]. Intoplicine is found to unwind DNA and to inhibit purified calf thymus topoisomerase II via a stabilization of the ternary cleavable complex^[2].