A phase II clinical trial of ZD1839 (Iressa™) in combination with docetaxel as first-line treatment in patients with advanced breast cancer

This was a phase II multi-institutional trial to determine the efficacy and tolerability of gefitinib (Iressa™) and docetaxel as first-line treatment in patients with metastatic breast cancer. All patients had histologically confirmed breast cancer with metastatic disease. They were permitted to have received adjuvant chemotherapy, but no prior docetaxel or prior chemotherapy for metastatic disease. Patients received gefitinib 250 mg once daily and docetaxel 75 mg/m² every 3 weeks, until tumor progression, toxicity or other reasons for discontinuation. Thirty-three patients were enrolled and received a median of 5 cycles of treatment. The clinical benefit rate was 51.5% (95% CI: 33.5-69.2%). There were 1 confirmed complete response and 12 confirmed partial responses, and the overall objective response rate was 39.4% (95% CI: 22.9 -57.9%). Four patients had stable disease for ≥ 24 weeks. The median duration of clinical benefit was 10.9 months (95% CI: 6.0-17.6 months). The most common reason for study discontinuation was disease progression (16 patients), followed by toxicity (ten patients). Toxicities were mainly attributable to docetaxel, including ≥ grade 3 neutropenia in 43% of patients. The combination of gefitinib and docetaxel is an active regimen in patients with previously untreated metastatic breast cancer, with a clinical benefit rate and toxicity profile in the range of that reported for docetaxel alone.