Clinical experience with the HER1/EGFR tyrosine kinase inhibitor erlotinib

In phase I trials in healthy volunteers and patients with refractory cancers, erlotinib (Tarceva) was well tolerated and showed activity against non-small-cell lung cancer and other tumors. The dose identified for further clinical development was 150 mg/d; at this dose, erlotinib achieves high exposure, with maximum concentrations greater than 2,000 ng/mL and 24-hour area under the concentration-time cure greater than 35,000 ng.h/L. In a phase II trial in 57 patients with previously treated advanced non-small-cell lung cancer, erlotinib treatment produced an objective response rate of 12.3% and a stable disease rate of 38.6%, with median duration of response of 19.6 weeks; median overall survival was 8.4 months and 1-year survival was 40%, with 9 patients remaining alive over follow-up of greater than 18 months. No grade 4 toxicity was observed, and grade 3 toxicity was minimal. In an ongoing phase II trial in bronchioloalveolar carcinoma, erlotinib treatment has produced objective response in 26% of 50 evaluable patients, with median duration of response not yet having been reached. An ongoing phase II trial is examining the combination of erlotinib with the angiogenesis inhibitor bevacizumab (Avastin) in previously treated non-small-cell lung cancer; phase I evaluation revealed no dose-limiting toxicities at tested doses and provided evidence of antitumor activity. Two phase III trials are examining erlotinib in combination with carboplatin (Paraplatin)/paclitaxel (the TRIBUTE trial) or cisplatin/gemcitabine (Gemzar) (the TALENT trial) as first-line treatment in advanced non-small-cell lung cancer. The phase III BR.21 trial is assessing erlotinib monotherapy in advanced refractory non-small-cell lung cancer. Results of these phase II trials will soon be available.