Hydroxycamptothecine (IC50 = 6.87 ± 0.77 × 10−6 M) and its stereoisomer S-10-Hydroxycamptothecine (IC50 = 7.22 ± 0.06 × 10−6 M) are DNA topoisomerase I inhibitors with anti-cancer activity (Fei et al., 2013). This evidence concerns the gene TOP1 and cancer.