Camptothecin (CPT) is an anticancer agent and has unique mechanism of action, which is the reversible inhibition of DNA topoisomerase I. The combination of CPTs and topoisomerase II inhibitors has synergistic activity in a variety of cancer cell lines by the mechanism of chromosomal aberrations including increasing sister chromatid exchanges, gene deletions, and gene rearrangements [10]. Here, TOP1 is linked to cancer.