Used in chemotherapy to treat various cancers, particularly ovarian cancer, small cell lung cancer, and cervical cancer. It functions by inhibiting topoisomerase I, an enzyme involved in DNA replication, leading to DNA damage and cancer cell death. Its ability to cross the blood-brain barrier makes it useful in treating brain tumors and cancers with central nervous system involvement. Administered intravenously, it is often used when other treatments have failed, offering a therapeutic option in advanced or recurrent disease settings.