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Iressa (Gefitinib) – Targeted Therapy Drug for Breast Cancer


Updated June 16, 2008

Iressa tablets

Iressa tablets

Photo © Gold Standard

Definition of Iressa:

Iressa (gefitinib) is a targeted therapy drug for cancer. So far, it has been used to treat non-small cell lung cancer (NSCLC) that has not responded to previous treatment, and is still being studied for treatment of metastatic breast cancer. It has not yet received FDA approval for this use.

Use for Breast Cancer:

Iressa can be used to treat metastatic breast cancer that is hormone receptor positive, and negative for the HER-2 receptor. In a Phase 2 study done at The University of Texas M. D. Anderson Cancer Center, patients who took Iressa and Arimidex (anastrozole) had longer progression-free survival than patients who received Arimidex alone. In addition, about half of the women in this study had "stable disease" for 6 months.

Other Uses for Iressa:

This drug has also been given to treat advanced non-small cell lung cancer and advanced lung cancer.

Also Known As:

Iressa, gefitinib, and ZD1839.

How Iressa Works:

Iressa is a epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, that blocks the HER1 protein. Iressa finds a HER1 positive cancer cell, enters it, and blocks the cell's ability to respond to growth signals. When the cancer cells can't receive growth signals, they fail to divide, and disease progression is stopped.

How You Take Iressa:

Iressa comes in 250 mg. orange tablets. Take Iressa daily, by mouth, with or without food. Be sure to take this drug at the same time every day. If you have trouble swallowing Iressa tablets, you can dissolve a tablet in half a glass of plain drinking water. Don't crush the tablet, just stir the water with a spoon until the tablet dissolves, then drink the mixture immediately. Take another half a glass of water, to make sure that you take all of the medicine.

If you are also taking Arimidex, you can take it at the same time you take your Iressa tablets. There is no generic version of Iressa available.

Before Beginning Iressa Treatment:

Iressa may interact badly with some drugs, vitamins, and nutritional supplements, so be sure to tell your doctor about of your medications. If you take herbs, such as St. John's Wort, be sure to let your doctor know. And if you have ever had pulmonary fibrosis (scarring of the lungs), or liver or kidney disease, your doctor needs to know, before you start taking Iressa.

Recommendations During Treatment:

  • Use reliable contraception –- avoid pregnancy.
  • Don't breastfeed while on Iressa, because it may harm your baby.
  • Stop smoking – ask your doctor if you need help.
  • Avoid alcohol and caffeine.
  • If you regularly eat grapefruit or drink grapefruit juice, discuss this with your doctor, as it may interfere with Iressa.

Risks of Using Iressa:

  • Allergic reaction to Iressa
  • May harm fetus, if you become pregnant during treatment
  • Possible future infertility
  • Low blood counts, greater danger of infections

Possible Side Effects:

Iressa is generally well-tolerated, but some patients will have side effects, and these can include:
  • Fatigue or weakness
  • Dry or itchy skin, rash, or acne*
  • Mucositis (irritated mucous membrane in your mouth)
  • Amenhorrea (monthly menstrual cycle stops)
  • Weight loss
* Women who develop acne during Iressa treatment always have the best response to this drug - a sign that it is working in their favor.

When to Call Your Doctor:
If you have any of these symptoms, call your doctor:

  • Fever of 100.5F or higher
  • Nausea
  • Vomiting
  • Diarrhea
  • Appetite loss
  • Eye pain, redness, or irritation, changes in vision, or eyelashes growing inside your eyelid
  • Unusual bruises or bleeding
  • Persistent cough, sore throat, pneumonia
  • Allergic symptoms: shortness of breath, swelling of feet or ankles, hives, swollen throat or tongue
FDAnews Drug Daily Bulletin. June 10, 2008, Vol. 5 No. 113. Curtailed Lung Cancer Drug Enhances Breast Cancer Therapy.

"Iressa shows promise for treatment of metastatic breast cancer when combined with hormonal therapy." Bio-Medicine, 5/16/2008.

MedlinePlus. National Institutes of Health. Gefitinib. Last Revised: 03/01/2007.

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