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How does Afinitor work?

Medically reviewed by Carmen Fookes, BPharm. Last updated on May 8, 2020.

Official Answer

by Drugs.com
  • Afinitor is called an mTOR inhibitor.
  • mTOR is a type of protein called a kinase that helps both healthy cells and cancerous cells get the energy they need.
  • Sometimes kinases become overactive and help certain cancers to grow.
  • Afinitor binds a specific protein called FKBP-12 and forms a complex which inhibits the activity of mTOR, reducing cell proliferation, the formation of new blood vessels, and glucose uptake.
  • Afinitor reduces the blood supply to cancer which slows down its growth.

Afinitor (everolimus) is a targeted medicine that may be used to treat various cancers. It interferes with cancer cell growth and slows the spread of cancer in the body. The dosage of Afinitor may vary depending on the condition being treated but the most common dosage for breast cancer is 10mg orally once a day.

Afinitor is usually taken every day for as long as it is working or until unacceptable side effects occur. It is meant to be taken as a long-term treatment. Afinitor may be taken either with or without food. It should be taken at approximately the same time each day.

How does Afinitor work?

Afinitor is called an mTOR inhibitor. mTOR stands for mammalian target of rapamycin, and it is a type of protein in the body called a kinase that helps both healthy cells and cancerous cells get the energy they need.

Sometimes kinases become overactive and help certain cancers to grow. Afinitor binds a specific protein called FKBP-12 and forms a complex which inhibits the activity of mTOR, reducing cell proliferation, the formation of new blood vessels, and glucose uptake. Afinitor reduces the blood supply to cancer which slows down its growth.

Trials have shown that the growth of estrogen-dependent and HER2+ breast cancer cells is inhibited by the effects of Afinitor. Combination treatment with other agents such as exemestane (Aromasin) for breast cancer enhances its effects.

What is Afinitor used to treat?

Afinitor may be used in the treatment of several different cancers, such as:

  • Hormone receptor-positive, HER2- negative breast cancer
  • Neuroendocrine tumors of the stomach, bowel, lung or pancreas
  • Kidney cancer
  • Tuberous Sclerosis Complex (TSC)- associated conditions or seizures.

What are the side effects of Afinitor?

Some of the more common side effects that occur with Afinitor include:

  • An increased risk of infection Anemia (may cause you to look pale)
  • Changes in blood glucose levels
  • Changes in taste
  • Cough
  • Diarrhea
  • Dry skin, itching, or a skin rash
  • Headaches
  • High cholesterol
  • Loss of appetite
  • Mouth ulcers or sores
  • Nausea
  • Nose bleeds
  • Shortness of breath
  • Swollen hands or feet
  • Tiredness or fatigue
  • Weight loss.

Other side effects, such as insomnia, high blood pressure, indigestion, aching or painful joints, hair thinning, and several others are less common, occurring in only about 1% of people taking Afinitor.

Side effects that may require a dosage reduction in Afinitor or may result in treatment discontinuation include:

  • Pneumonitis (Inflamamtion of lung tissue)
  • Stomatitis (inflammation of the mouth and lips)
  • Metabolic events (such as high blood sugar or high cholesterol)
  • Thrombocytopenia (low blood platelet counts)
  • Neutropenia (low neutrophils).

How effective is Afinitor?

In the Bolero-2 study, women who were assigned Afinitor in combination with exemestane (Aromasin) were more likely to experience a complete response (3/485) or a partial response (58/485) compared with those who were assigned a placebo (no complete responses and only 4/239 partial responses). There was no difference in overall survival rate in those assigned Afinitor combined with exemestane compared with those assigned placebo and exemestane after 39.3 months (just over 3 years).

A significant difference in progression-free survival was reported for Afinitor for pancreatic neuroendocrine tumors and neuroendocrine tumors of gastrointestinal or lung origin.

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