Teniposide is a chemotherapy medication primarily used to treat certain types of cancer, including acute lymphoblastic leukemia and neuroblastoma. It works by inhibiting the enzyme topoisomerase II, which is essential for DNA replication and cell division, ultimately leading to cancer cell death. This drug is typically administered intravenously and may be part of a combination therapy with other anticancer agents. Common side effects include nausea, vomiting, and low blood cell counts, which can increase the risk of infections and bleeding. Regular monitoring by healthcare professionals is essential during treatment.