Topoisomerase II (Topo II) inhibitors are cell cycle-specific DNA-damaging agents and often correlate with secondary leukemia with chromosomal translocations involving the mixed-lineage leukemia/myeloid lymphoid leukemia (MLL) gene on chromosome 11 band q23 (11q23).
These results suggest that site specific cleavage within the MLL bcr induced by topoisomerase II inhibitors may be an early step leading to MLL translocations and secondary leukemia.