Taira, Naruto

Human esophageal cancers have been shown to express high levels of epidermal growth factor receptor (EGFR) and a relationship between high EGFR expression and local advance, the number of lymph node metastases, life expectancy, and sensitivity to chemo-radiotherapy has been demonstrated. We examined the use of gefitinib, an orally active EGFR-selective tyrosine kinase inhibitor, as a new strategy for treatment of esophageal carcinoma. The effects of gefitinib were evaluated in monotherapy and in combination with radiotherapy in human esophageal carcinoma cell lines. Gefitinib produced a dose-dependent inhibition of cellular proliferation in all of the 8 esophageal carcinoma cell lines examined, with IC50 values ranging from 5.7 microM to 36.9 microM. In combination, gefitinib and radiotherapy showed a synergistic effect in 2 human esophageal carcinoma cell lines and an additive effect in 5 cell lines. Western blotting demonstrated that gefitinib blocked activation of the EGFR-extracellular signal-regulated kinase (Erk) pathway and the EGFR-phosphoinositide-3 kinase (PI3K)-Akt pathway after irradiation. These results suggest that further evaluation of EGFR blockade as a treatment for esophageal cancer should be performed, and that radiotherapy combined with EGFR blockade may enhance the response of esophageal carcinoma to therapy.

Toremifene citrate is expected to prevent drug resistance in cancer patients by inhibiting p-glycoprotein activity. The safety and efficacy of combination therapy with high-dose toremifene citrate and paclitaxel were investigated. Between December 2003 and June 2004, 15 women with a mean age of 53 years old with metastatic breast cancer were enrolled. The administration schedule was 80mg/m2 of paclitaxel given on Days 1, 8, and 15, and 120mg/day of toremifene citrate orally administered starting on Day 18. On Days 32 and 39, paclitaxel was concurrently administered again. Toxicities, response rate, and time to treatment failure were assessed. All patients had been treated with endocrine or chemotherapy. Grade 3 leukopenia occurred in 2 patients on the administration of paclitaxel alone, and grade 3 febrile neutropenia occurred in 1 patient given the combination therapy. There was no grade 3 or greater non-hematological toxicity. There was no complete response and 1 partial response, producing a response rate of 6.7%. Median time to treatment failure was 2.7 months. Combination therapy of paclitaxel and toremifene was safe and well tolerated with minimal toxicity. Further clinical trials targeting patients with functional p-glycoprotein are warranted.