How Do Antineoplastic mTOR Kinase Inhibitors Work?

Antineoplastic mammalian target of rapamycin (mTOR) inhibitors are a class of drugs used to treat breast cancer, advanced renal cell carcinoma (cancer that begins in the kidneys), subependymal giant cell astrocytoma (a type of brain tumor), and seizures (a sudden, uncontrolled electrical disturbance in the brain) and as an immunosuppressant to prevent transplant rejection (attack of the transplanted organ by the immune system of the person who received the organ) in adults who have received kidney or liver transplants.

mTOR kinase inhibitors are a derivative of rapamycin that blocks the activity of the mTOR pathway, which regulates growth factors responsible for stimulating cell growth and controlling cell division and angiogenesis (development of new blood vessels).

mTOR kinase inhibitors bind to an intracellular protein (FKBP-12), and the resulting protein-drug complex inhibits the activity of mTOR, leading to G1 growth arrest in treated tumor cells and thus blocking the mTOR pathway, which is overactive in certain cancerous cells.

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

mTOR kinase inhibitors work in the following ways:

• They belong to a class of medications called "kinase inhibitors" that work by decreasing the blood supply to cancer cells and preventing their growth and reproduction.
• They prevent transplant rejection by decreasing the activity of the immune system.

Antineoplastic mTOR kinase inhibitors are used to treat conditions such as:

• Breast cancer
• Renal cell carcinoma
• Advanced neuroendocrine tumors
• Renal angiomyolipoma (benign renal neoplasm composed of fat, vascular, and smooth muscles)
• Subependymal giant cell astrocytoma (benign, slow-growing tumor that usually forms in the walls of fluid-filled spaces in the brain)
• Partial onset seizures (seizure that starts in one area of the brain)
• Kidney transplant rejection
• Liver transplant rejection

Some of the common side effects include:

• Nausea
• Vomiting
• Constipation
• Diarrhea
• Headache
• Altered taste sensation
• Dryness of mouth
• Tiredness/weakness
• Muscle/joint/back pain
• Mouth sores
• Loss of appetite

Other rare side effects include:

• Dizziness 
• Fatigue 
• Weight loss
• Hair loss
• Chest pain
• Anemia (low red blood cell count)
• Insomnia 
• Shortness of breath
• Chills, sore throat, fever, or cough
• Rash/hives/itching
• Hypertension (high blood pressure)
• Hypophosphatemia (low blood phosphate level)
• Painful, frequent, burning, or difficult urination
• Peripheral edema (swelling of lower legs or hands)
• Increased creatinine 
• Unusual bleeding or bruising
• Menstrual irregularities
• Hyperglycemia (high blood glucose level)
• Epistaxis (bleeding from the nose)

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 mTOR kinase inhibitors include:

• Afinitor
• Afinitor disperz
• Everolimus
• Temsirolimus
• Torisel
• Zortress