topoisomerase II inhibitor
(TOH-poh-i-SAH-meh-rays … in-HIH-bih-ter)
A substance that blocks the activity of the enzyme topoisomerase II, which cuts and repairs tangled strands of DNA. Topoisomerase II is involved in cell division and growth, so blocking activity of this enzyme may kill cancer cells. Some topoisomerase II inhibitors are being used to treat cancer.