Objective: To provide a comprehensive review of the clinical pharmacology and toxicology of gefitinib, with particular attention to its use in early clinical trials.
Data source: A PubMed search was conducted using the terms ZD1839, gefitinib, and epidermal growth factor receptor (EGFR). All data from this search were reviewed and other relevant papers identified. The abstracts from the annual meetings of the American Society of Clinical Oncology were also reviewed.
Data extraction: The aim of the review was to be comprehensive and descriptive. The authors reviewed studies and case reports containing information deemed to be of interest.
Conclusions: EGFR is expressed, overex-pressed, or disregulated in a variety of human solid tumors, resulting in an enhancement of tumor growth. Gefitinib is a selective reversible inhibitor of EGFR that has shown activity in several tumor types. As an oral agent, it is extensively metabolized in the liver through the cytochrome P450 enzyme system, particularly the isoenzyme CYP3A4. In the phase II, IDEAL 1 and 2 trials, gefitinib has shown a response rate of 8.8% -18.4% in refractory lung cancer. Clinical trials in various other nonlung cancer patients include studies of gefitinib as a monotherapy or in combination with various chemotherapy, radiation, and/or hormone therapy regimens. Skin and gastrointestinal toxi-cities are the most frequent adverse events of gefitinib. Recently, interstitial pneumonia has emerged as one of the serious adverse effects among gefitinib patients. In summary, the role of gefitinib in combination or as a monotherapy for a variety of cancers is still evolving.