Questions and Answers on Iressa (gefitinib)

On June 17, 2005 the The Food and Drug Administration (FDA) has approved new labeling for gefitinib (Iressa) that limits use to patients with cancer who in the opinion of their treating physician, are currently benefiting, or have previously benefited, from Iressa treatment. In addition, AstraZeneca will distribute the drug under the Iressa Access Program. For more, please read the "Questions and Answers on Iressa's (gefitinib) New Labeling" article.


Iressa (gefitinib) is a groundbreaking new type of anti-cancer drug for people with the most common type of lung cancer. It is different from all prior chemotherapy. That is, Iressa works by uniquely blocking cellular enzymes that stimulate cell growth. So, in the future, look for the emergence of other (hopefully more effective) anti-cancer drugs that work at specific cellular or molecular sites.

With this approval by the Food and Drug Administration (FDA), patients having advanced lung cancer that is unresponsive to standard treatment now will have at least some treatment available to them. Credit the FDA for the relatively rapid availability of this drug. You see, Iressa was approved under the FDA's accelerated approval program. This program provides patients with serious disease earlier access to promising new drugs.

Leslie J. Schoenfield, M.D., Ph.D.
Medical Editor, MedicineNet.com


1. What is Iressa and how does it work?

Iressa is a new anticancer drug that inhibits an enzyme (tyrosine kinase) present in lung cancer cells, as well as other cancers and normal tissues, that appears to be important to the growth of cancer cells. The active ingredient in Iressa is gefitibib.

2. What is Iressa used to treat?

Iressa is used as a single agent for the treatment of non-small cell lung cancer (NSCLC) that has progressed after, or failed to respond to two other types of chemotherapy (drugs used to kill cancer cells). Iressa is not indicated as the first chemotherapy drug given (first-line therapy) for the treatment of NSCLC because it has shown no benefit in two large, well-controlled studies when used in that setting.

3. What is NSCLC?

Lung cancer is divided into two major classes: small cell lung cancer and non-small cell lung cancer. NSCLC is the most common type of lung cancer, accounting for almost 80% of lung cancers. There are five types of NSCLC, each of which has different kinds of cancer cells. The cancer cells of each type differ in size, shape, and chemical make-up, and grow and spread in different ways.

4. Is Iressa taken alone or is it taken in combination with other chemotherapy drugs?

Iressa is taken alone, not with other chemotherapy.

5. Is Iressa a cure for NSCLC?

In the third line setting, i.e., after failure of two other agents, Iressa reduced tumor volume substantially in about 10% of people. There were no cures.

6. What is accelerated approval?

Accelerated approval is a program the FDA developed to make new drug products available for life threatening diseases when they appeared to provide a benefit over available therapy (which could mean there was no existing effective treatment). Under this program, Iressa is approved on the basis of early clinical study evidence (such as tumor shrinkage) suggesting that the drug is reasonably likely to have a valuable effect on survival or symptoms. The approval is granted on the condition that the manufacturer must continue testing to demonstrate that the drug indeed provides therapeutic benefit to the patient. If it does not, the FDA can withdraw the product from the market more easily than usual.

7. How many clinical trials were performed with Iressa and what did they show?

The study on which FDA based it approval included 216 patients 139 of whom had failed treatment with two other chemotherapy treatments. In this trial, approximately 10% of patients responded to Iressa with a decrease in tumor size.

The sponsor also presented to FDA the results of two large (about 1000 patients each) clinical studies with Iressa as initial therapy for lung cancer. In these studies all patients received, standard combination chemotherapy and were randomly given, in addition, either Iressa or a placebo. In these studies there was no effect of Iressa on survival, time to further growth of cancer, or on tumor size.

8. Is Iressa approved in other countries?

Yes, Iressa is approved in Japan.