How Do Antineoplastic Topoisomerase Inhibitors Work?

Antineoplastic topoisomerase inhibitors are a class of drugs used to treat various cancers including colorectal cancer (cancer that begins in the large intestine), pancreatic cancer, breast cancer, gastric cancer (cancer of the stomach), and small cell lung cancer.

Antineoplastic topoisomerase inhibitors are a synthetic, water-soluble analog (derivatives) of the natural chemical compound camptothecin, a product extracted from the bark of the tree Camptotheca acuminata. They are antineoplastic drugs that work by inhibiting the activity of DNA type I and type II topoisomerases (enzyme that relieves torsional strain in DNA by opening single strand breaks), thus preventing religation of the DNA strand by binding to topoisomerase I-DNA complex, eventually leading to double-strand DNA breakage and cell death.

Topoisomerase inhibitors are administered via intravenous (into a vein) and oral routes.

Topoisomerase inhibitors work in the following ways:

• They belong to a class of medications called "antibody-drug conjugates" that work by stopping the growth of cancer cells.
• They are a derivative of camptothecin (a chemical compound) that works by inhibiting an enzyme known as “topoisomerases,” preventing the relegation of DNA, thus leading to apoptosis (death of cells that occurs as a normal and controlled part of an organism’s growth or development).

Antineoplastic topoisomerase inhibitors are used to treat conditions such as:

• Colorectal cancer 
• Pancreatic cancer 
• Urothelial cancer
• Ovarian cancer
• Breast cancer
• Gastric cancer
• Small cell lung cancer
• Cervical cancer

Some of the common side effects include:

• Nausea
• Vomiting
• Constipation
• Heartburn
• Mouth sores
• Back pain
• Diarrhea
• Abdominal pain
• Headache
• Tiredness/weakness
• Loss of appetite
• Altered taste sensation
• Dry skin/eyes

Other rare side effects include:

• Dizziness 
• Fatigue 
• Hair loss
• Weight loss
• Anemia (low red blood cell count)
• Insomnia (trouble falling and/or staying asleep)
• Chest pain
• Shortness of breath
• Chills, sore throat, fever, or cough
• Thrombocytopenia (low blood platelet count)
• Peripheral edema (swelling of lower legs or hands)
• Rash/hives/itching
• Hypokalemia (low blood potassium level)
• Hypophosphatemia (low blood phosphate level)
• Hypocalcemia (low blood calcium level) 
• Upper respiratory tract infection
• Yellowing of skin or eyes
• Hypotension (low blood pressure)

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of antineoplastic topoisomerase inhibitors include:

• Camptosar
• Enhertu
• Fam-trastuzumab deruxtecan-nxki
• Hycamtin
• Irinotecan
• Irinotecan liposomal
• Onivyde
• Sacituzumab govitecan
• Sacituzumab govitecan-hziy
• Topotecan
• Trastuzumab deruxtecan
• Trodelvy