Belotecan is a drug used in chemotherapy. It is a semi-syntheticcamptothecin analogue indicated for Small Cell Lung Cancer and Ovarian Cancer, approved in South Korea under the trade name Camtobell(R), presented in 2 mg vials for injection. The drug is marketed by ChongKunDang Pharmaceuticals  since 2003 
Belotecan blocks topoisomerase I with a pIC50 of 6.56, stabilizing the cleavable complex of topoisomerase I-DNA, which inhibits the religation of single-stranded DNA breaks generated by topoisomerase I; lethal double-stranded DNA breaks occur when the topoisomerase I-DNA complex is encountered by the DNA replication machinery, DNA replication is disrupted, and the tumor cell undergoes apoptosis. Topoisomerase I is an enzyme that mediates reversible single-strand breaks in DNA during DNA replication.