The FDA ( Food and Drug Administration ) has approved Iressa ( Gefitinib ) for the first-line treatment of patients with metastatic non-small cell lung cancer ( NSCLC ) whose tumors harbor specific types of epidermal growth factor receptor ( EGFR ) gene mutations, as detected by an FDA-approved test.
Lung cancer is the leading cause of cancer-related death among men and women in the U.S. and, though more common in men, the number of deaths from lung cancer in women is increasing.
According to the National Cancer Institute ( NCI ), an estimated 221,200 Americans will be diagnosed with lung cancer, and 158,040 will die from the disease this year.
NSCLC is the most common type of lung cancer. Mutations in the EGFR gene are present in about 10% of NSCLC tumors.
Iressa is a kinase inhibitor that blocks proteins that promote the development of cancerous cells with certain EGFR mutations. It is intended for the treatment of patients whose tumors express the most common types of EGFR mutations in NSCLC ( exon 19 deletions or exon 21 L858R substitution gene mutations ).
The therascreen EGFR RGQ PCR Kit was approved as a companion diagnostic test to identify patients with tumors having the EGFR gene mutations in order to determine which patients would be appropriate for treatment with Iressa.
The FDA granted Iressa orphan product designation for the treatment of EGFR mutation-positive metastatic NSCLC.
Orphan product designation is given to drugs intended to treat rare diseases, which provides financial incentives ( like tax credits, user fee waivers, and eligibility for market exclusivity ) to promote their development.
The efficacy and safety of Iressa for this use was demonstrated in a multi-center, single-arm clinical trial of 106 patients with previously untreated, EGFR mutation-positive metastatic NSCLC.
The study’s primary endpoint was objective response rate, or the percentage of patients who experienced complete and partial shrinkage or disappearance of the tumors after treatment.
Participants received Iressa 250 mg once daily.
Results showed that tumors shrank in about 50% of patients after treatment and this effect lasted an average of six months.
The response rates were similar in patients whether their tumors had EGFR exon 19 deletions or exon 21 L858R substitution mutations.
These results were supported by a retrospective analysis of another clinical trial, which identified a subgroup of 186 patients with EGFR mutation-positive metastatic NSCLC receiving first-line treatment.
Patients were randomized to receive Iressa or up to six cycles of Carboplatin / Paclitaxel.
The results from this subgroup suggested an improvement in progression-free survival with Iressa compared to Carboplatin / Paclitaxel.
Iressa may cause serious side effects including interstitial lung disease, liver damage, gastrointestinal perforation, severe diarrhea and ocular disorders.
The most common side effects of Iressa are diarrhea and skin reactions ( including rash, acne, dry skin and pruritus, or itching ).
Iressa originally received accelerated approval in 2003 for the treatment of patients with advanced NSCLC after progression on Platinum doublet chemotherapy and Docetaxel.
Iressa was voluntarily withdrawn from the market after subsequent confirmatory trials failed to verify clinical benefit.
This current approval is for a different patient population ( EGFR mutation-positive, previously untreated ) than the 2003 approval. ( Xagena )
Source: FDA, 2015