Iressa (gefitinib) Versus Tarceva (erlotinib)
Iressa and Tarceva are tyrosine kinase inhibitors approved for first-line treatment for non-small cell lung cancer (NSCLC). Lung cancer is the leading cause of cancer-related death in the United States and non-small cell lung cancer is the most common type of lung cancer. Although both targeted therapies are in the same drug class, they differ in a number of ways. Here is an overview of the similarities and differences between Iressa and Tarceva.
What are Iressa and Tarceva approved for?
Iressa is approved for first-line treatment of NSCLC that has metastasized and the cancer cells have either a deletion in exon 19 or a modification in the exon 21 of the EGFR gene. Exons are the coding sections of the gene; exon 19 and 21 code for the tyrosine kinase. Once an exon is modified or removed, the tyrosine kinase is unable to work as normal.
Tarceva is approved for:
What is the mechanism of action of Iressa and Tarceva?
Iressa and Tarceva are tyrosine kinase inhibitors. They work by interfering with the function of epidermal growth factor receptor (EGFR). Epidermal growth factor receptors are found on the surface of normal and cancer cells and are involved in processes that control cell growth and how cells multiply. Iressa and Tarceva block the action of tyrosine kinase which is an enzyme that EGFR genes use for signaling other cells and promoting cell growth and multiplication of cells. By blocking the action of tyrosine kinase, Iressa and Tarceva reduce the activity of EGFR genes in cancer cells. This prevents tumor cells from growing and shortens the life span of the cancer cell. Iressa and Tarceva affect EGFR in cancer cells more than EGFR in normal cells.
Iressa is specifically used to treat lung cancer cells that have EGFR exon 19 deletions or exon 21 substitution mutations. EGFR exon 19 deletions or exon 21 substitution mutations in lung cancer cells promote tumor cell growth, and prevent the death of cancer cells, promote the formation of new blood cells, and help cancer cells migrate to the rest of the body. Therefore, these EGFR mutations lead to uncontrolled growth of cancerous cells.
The FDA approved Iressa in July 2015 while Tarceva was approved in November 2004.
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