University of Colorado Cancer Center, Aurora, Colorado, USA.
Lung cancer is the most common cancer and a highly lethal disease, with improvements in survival rates being dependent on advances in early detection and improved systemic therapies applied to surgery and/or irradiation in early-stage disease. Non-small cell lung cancer (NSCLC) represents around 80% of all lung cancers, and unfortunately at diagnosis most patients have advanced unresectable disease with a very poor prognosis. Indeed, 30%-40% of patients treated with first-line therapy will subsequently be candidates for second-line treatment. Current U.S. Food and Drug Administration-approved second-line treatments are docetaxel (a taxane), pemetrexed (a folate antimetabolite), and erlotinib (an epidermal growth factor receptor [EGFR] tyrosine kinase inhibitor [TKI]). Gefitinib, another EGFR TKI, currently has only limited use in North America and is not available in Europe. These and other new molecular-target-specific agents may have the potential to maximize therapeutic benefit while minimizing toxicity to normal cells. Overexpression of EGFR is reported to occur in 40%-80% of NSCLC cases, and EGFR mutations are associated with a significantly higher response rate and longer duration of response following treatment with EGFR TKIs. Another option is antiangiogenesis: the growth and persistence of solid tumors and their metastases are angiogenesis dependent, and so antiangiogenic therapies have been developed, such as the use of TKIs that block the vascular endothelial growth factor receptor. In fact, many commonly used chemotherapeutic drugs have antiangiogenic activity. Ongoing studies are focusing on patient selection and targeted therapies, and there are many new agents undergoing clinical trials.