Chemical structure of Gefitinib

Iressa (gefitinib) is a targeted anti-cancer therapy designated for certain patients with advanced non-small cell lung cancer (NSCLC). An oral tablet taken every day for cycles of 28 days1, Iressa is what's known as an EGFR tyrosine kinase inhibitor: EGFR is a protein found in high levels on the surface of many cancer cells.

When it binds with another protein, EGF, this attachment stimulates the cell to begin dividing. Iressa gets between these proteins by attaching to the EGFR and inhibiting the cell from dividing, thereby slowing tumor growth2.

What it's effective for and why

Initially approved by the FDA in 2003 for patients with non-small cell lung cancer (NSCLC), the agency re-evaluated Iressa's safety and efficacy in 2005 and determined that the drug did not extend the lives of patients with NSCLC. Its indications were thus scaled back significantly; today, the US National Library of Medicine recommends that Iressa be taken only by patients whom it has previously benefitted3.

Iressa is only available thanks to a limited access program, and can only be obtained through special order pharmacies. It is the first anti-cancer drug to have received accelerated FDA approval only to be partly rescinded later, although the FDA appears unwilling to remove it fully from the market4.

Iressa side effects: Overview

Like most if not all modern anti-cancer drugs, Iressa may cause side effects, some simply unpleasant—such as dry skin, acne, itching or skin rashes—and some significantly more serious—such as loss of appetite, nausea and vomiting (despite once being considered nonemetogenic5), an allergic reaction resembling hives, or the swelling of certain areas of the body, in particular in the extremities (arms and legs). Meanwhile, some of the more peculiar—and serious—side effects of Iressa involve the eyes, they include pain, redness, irritation or swelling, along with unexplained changes in vision, and finally, the possible growth of eyelashes on the inside of the eyelid6.


  1. Kris MG et al. "Efficacy of gefitinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in symptomatic patients with non-small cell lung cancer: a randomized trial." JAMA 2003 Oct 22;290(16):2149-58.
  2. Definition of EGFR
  3. US National Library of Medicine: Gefitinib
  4. Iressa's revised labeling guidelines
  5. Boyiadzis, Michael M. et al. Hematology-Oncology Therapy. 2007. New York: McGraw Hill, Medical Publishing Division.
  6. Gefitinib: Side effects


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