TOPOI/PARP-1-IN-2 (compound 6c) is a dual PARP-1 and topoisomerase 1 (TOPO-1) inhibitor with IC 50 s of 32.2 nM and 46.2 nM, respectively. TOPOI/PARP-1-IN-2 shows a selectivity for PARP-1 over PARP-2. TOPOI/PARP-1-IN-2 disrupts the cell cycle at the S phase and induces apoptosis in NCI-60 cancer cell lines.