Afeletecan is a water-soluble camptothecin derivative. Afeletecan stabilizes the topoisomerase I-DNA covalent complex and forms an enzyme-drug-DNA ternary complex. Both the initial cleavage reaction and religation steps are inhibited and subsequent collision of the replication fork with the cleaved strand of DNA results in inhibition of DNA replication, double-strand DNA breakage, and triggering of apoptosis.