Gefitinib (Iressa) trials in non-small cell lung cancer

Gefitinib (Iressa™) is a synthetic anilinoquinazoline capable of inhibiting the epidermal growth factor receptor tyrosine kinase in vitro at nanomolar concentrations. In phase I trials, gefitinib was well tolerated at doses above that required to induce antitumor effects in vitro. Notably, antitumor activity was observed in lung cancer patients. These findings resulted in the initiation of phase II trials employing gefitinib monotherapy in patients with recurrent non-small cell lung cancer (the so-called IDEAL trials). Study participants were randomized to 250 mg or 500 mg of gefitinib per day. Objective response rates between 10 and 20% were achieved with minimal host related toxicity (mainly acne like rash and mild diarrhea). Median survivals ranged between 6 and 8 months. Subsequently, phase III trials (the so-called INTACT trials) combined gefitinib and chemotherapy in chemonaive patients with advanced non-small cell lung cancer. These trials failed to demonstrate a survival advantage with the addition of gefitinib to standard platinum-based chemotherapy regimens. However, overall host related toxicities were not substantially worsened with the addition of gefitinib to chemotherapy. Further studies employing single agent gefitinib as well as regimens employing a different sequencing of chemotherapy and gefitinib are planned in recurrent and previously untreated lung cancer patients.