Introduction
Gefitinib is a selective tyrosine kinase receptor inhibitor used in the therapy of non-small cell lung cancer. Gefitinib therapy is associated with transient elevations in serum aminotransferase levels and rare instances of clinically apparent acute liver injury.
Background
Gefitinib (ge fi' ti nib) is a selective inhibitor of the tyrosine kinase receptor of epidermal growth factor (EGFR), which is often mutated and over expressed in cancer cells, particularly non-small cell lung cancer and some forms of breast cancer. The mutated EGF tyrosine kinase receptor is constitutively expressed which causes unregulated cell growth and proliferation. By inhibition of this growth factor receptor, gefitinib blocks the intracellular Ras signaling transduction cascade, which results in inhibition of the malignant cell growth. Highest rates of response to gefitinib are seen in patients with activating mutations of EGFR in the tumor tissue. Gefitinib received approval for use in the United States in 2009 for the treatment of advanced non-small cell lung cancer after failure of other therapies, but has been available in Japan since 2002. Gefitinib is available in tablets of 250 mg under the brand name Iressa. The recommended dose is 250 mg by mouth once daily, with dose modification based upon tolerance. Side effects are common and include diarrhea, nausea, vomiting, anorexia, mouth ulcers, conjunctivitis, rash, pruritus and fatigue. Uncommon serious side effects include interstitial lung disease and corneal erosions.
