Epidermal growth factor receptor tyrosine kinase inhibitors: evolving role in the treatment of solid tumors

Inhibitors of epidermal growth factor receptor tyrosine kinase (EGFR-TK) activity have shown promise as novel anticancer agents in a variety of common solid tumors. In preclinical studies and phase I trials, tumor responses to EGFR-TK inhibitors (EGFR-TKIs), such as gefitinib (Iressa, AstraZeneca Pharmaceuticals LP, Wilmington, DE) and erlotinib (Tarceva, OSI Pharmaceuticals, Melville, NY, and Genentech, Inc., South San Francisco, CA) were observed in heavily pretreated patients with advanced non-small cell lung cancer (NSCLC), head and neck cancer, breast cancer, colorectal cancer, and other solid tumors. Subsequent phase II studies resulted in tumor responses, disease stabilization, symptom improvement, and improved quality of life in patients with advanced NSCLC who had received prior platinum-based chemotherapy or platinum and docetaxel chemotherapies. Side effects related to treatment with EGFR-TKIs were generally mild, reversible, and noncumulative. Severity and frequency of drug-related adverse events were related directly to dose. The potential role of EGFR-TKIs in treating other solid tumors currently is being studied. Furthermore, research is being conducted to explore the potential use of EGFR-TKIs in novel combinations with chemotherapy, radiation therapy, endocrine therapy, and other molecular targeted therapies.