Chimmitecan ((S)-9-Allyl-10-hydroxycamptothecin) is a potent inhibitor of topoisomerase I and displays outstanding activity in vitro and in vivo.

Chimmitecan was highly cytotoxic (IC50s in the nanomolar range) to a wide variety of tumor cells, including leukemia, lung cancer, gastric cancer, hepatocellular cancer, colon cancer, breast cancer, ovarian cancer, and cervical cancer, and rhabdomyosarcoma cells[1].

Chimmitecan (i.v. administration, twice for HCT-116 and thrice for the other tumors per week) caused a dramatic and dose-dependent suppression of tumor growth in all four tumor models. At a dosage of 15 mg/kg, the T/C (%) values were 17.6% (HCT-116), 24.2% (MDA-MB-435), 28.2% (BEL-7402), and 23.0% (A549). when given thrice per week for 2 weeks, chimmitecan (orally administration) inhibited the growth of the A549 xenograft at dosages as low as 4.5 mg/kg, and significant antitumor activity was observed at a dosage of 9 mg/kg[1].