Iressa (gefitinib) is a prescription medicine for people with non-small cell lung cancer (NSCLC) that has spread to other parts of the body. NSCLC is the most commonly diagnosed type of lung cancer, accounting for 80 to 85 percent of all lung cancer cases.
Iressa is used in people with certain mutations in the epidermal growth factor receptor (EGFR) gene who have not had previous cancer treatments. The EGFR gene encodes for a protein found in the cell membrane. The protein crosses the cell membrane, leaving one end of the protein inside the cell and the other projecting from the outer surface. This allows the receptor to bind to other proteins, called ligands, outside the cell and receive signals that help the cell respond to its environment. Mutated EGFR plays a part in cancer growth by sending out signals that make the cells grow and divide erratically.
How Iressa works
Iressa is a kinase inhibitor that blocks proteins that promote the development of cancerous cells with certain EGFR gene mutations. The drug attaches itself to a certain abnormal type of EGFR protein on lung cancer cells. By doing so, it has been shown to slow the growth of these cells and may help reduce the size of tumors.
It is used especially for the treatment of people whose tumors have EGFR mutations called exon 19 deletions or exon 21 L858R substitution. A polymerase chain reaction (PCR) kit named therascreen EGFR was approved as a diagnostic test to identify patients with these mutations in order to determine if it is appropriate to treat them with Iressa.
Iressa in clinical trials
The safety and effectiveness of Iressa were assessed in a Phase 4 clinical trial (NCT01203917) called IFUM. The study’s primary outcome target was the objective response rate, which is the percentage of participants who experienced a complete or partial shrinkage or clearance of their tumor after treatment. The study included 106 participants who were given 250 mg of Iressa once daily. Tumors shrank in half of the participants (53 out of 106), with the effect of the drug lasting for about six months. Iressa showed similar response rates in participants with exon 19 deletions or exon 21 L858R substitutions.
A retrospective analysis of another study (NCT00322452) called IPASS, which identified a subgroup of 186 participants with the EGFR mutation receiving first-line treatment, supported these results. This study assessed the effect of Iressa in comparison to carboplatin or Taxol (paclitaxel) as a first-line treatment. Participants received either Iressa, or up to six cycles of carboplatin or Taxol. The results suggested an improvement in progression-free survival with Iressa (10.9 months) compared to carboplatin or Taxol (5.5 months).
Other details
The U.S. Food and Drug Administration (FDA) has granted Iressa orphan drug designation in 2015 for the treatment of NSCLC with EGFR mutations.
Iressa is an oral therapy that can be taken with or without food. In order to make swallowing easier, the tablet can be dissolved in water.
Iressa may cause some serious side effects, such as breathing problems, swelling of the lips, tongue or face, lung or liver inflammation that may lead to death, stomach perforation, diarrhea, eye problems, and skin reactions, such as redness, rash, itching, and acne.
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