Intoplicine

Intoplicine (RP 60475), an antitumor derivative in the 7H-benzo[e]pyrido[4,3-b]indole series, is a DNA topoisomerase I and II inhibitor. Intoplicine strongly binds DNA (K_A = 2 x 10⁵ /M) and thereby increases the length of linear DNA^[1][2]. IC50 & Target: DNA topoisomerase^[1] In Vitro: With 1-hour exposure to Intoplicine at final concentrations of 2.5 micrograms/mL and 10.0 micrograms/mL, 26% and 54% of the assessable specimens shows positive in vitro responses, respectively^[2].
With continuous exposure to Intoplicine at concentrations of 0.25 micrograms/mL and 2.5 micrograms/mL, 16% and 71% of the assessable specimens showed positive responses, respectively^[2].
Activity is seen against breast (71%), non-small-cell lung (69%), and ovarian (45%) cancer colony-forming units at a Intoplicine concentration of 10.0 micrograms/mL after 1-hour exposure^[2]. In Vivo: At the highest non-toxic dose (HNTD) (6 mg/kg/injection, total dose, 36 mg/kg), Intoplicine shows highly active with a T/C of 0% and a corresponding total log cell kill of 3^[3].