Cytotoxic drugs are powerful chemotherapy medications used to kill cancerous cells. Different types of cytotoxic drugs interfere with varying cellular activities to induce cell death, with most disrupting some aspect of cell replication. If cancer cells cannot multiply, the disease can potentially be controlled. Although cancer cells are the target of cytotoxic chemotherapy, these medicines also interact with healthy cells that are actively dividing.
Cancerous tumors grow by continuously replicating--the process of one cell dividing into two new cells. As a cell prepares to divide, it makes a copy of its genetic material. Chemicals called nucleosides are the building blocks of the cell's genetic material, or genome. Emory University Winship Cancer Institute explains that nucleoside antagonists are cytotoxic drugs that disrupt the genome copying process, thereby preventing cell replication and lethally damaging the original cell. Examples of nucleoside antagonists include 5-fluorouracil, 6-mercaptopurine, arabinosylcytosine, capecitabine, clofarabine, cytarabine, dacarbazine, fludarabine, gemcitabine and nelarabine. These medications are frequently used to treat many types of cancer, including melanoma, lymphoma and leukemia and cancers of the adrenal gland, bladder, breast, cervix, colon, esophagus, endometrium, liver, lungs, ovaries, pancreas, prostate, rectum and stomach.
Intercalating agents are cytotoxic drugs that bind to a cell's genetic material, arresting the copying process and distorting its chemical structure, notes chemist Charles Ophardt, Ph.D., of Elmhurst College. Oxaliplatin, cisplatin and carboplatin are platinum-containing intercalating agents, which are frequently used in combination with other cytotoxic chemotherapy drugs. Combination therapy with these agents may be used to treat cancers of the adrenal gland, bladder, bone, brain, head and neck, breast, cervix, colon, rectum, endometrium, esophagus, liver, lung, ovary and testicle.
Cell replication, or mitosis, requires formation of a structure called a spindle, which provides the framework for dividing the copied genetic material between the intended new cells. Spindle inhibitors disrupt the formation of this essential structure, explains Emory University Winship Cancer Institute. Spindle inhibitors include the taxane drugs docetaxel and paclitaxel, ixabepilone and the vinca alkaloids vindesine, vincristine, vinorelbine and vinblastine. These drugs may be used alone or in combination therapy regimens for cancers of the breast, colon, rectum, head and neck, stomach, ovary, lungs, prostate and testicle. Spindle inhibitors are also used to treat leukemias, lymphomas, rhabdomyosarcomas and neuroblastomas.
Folate inhibitors interfere with the production of the nucleosides required for copying genetic material for cell replication, notes Emory University Winship Cancer Institute. Methotrexate and pemetrexed are folate inhibitors often used for the treatment of lymphoma, leukemia, choriocarcinoma, mesothelioma and cancers of the bone, bladder, head, neck, breast and lungs.