Capecitabine with Weekly Paclitaxel for Advanced Breast Cancer: A Phase I Dose-Finding Trial

Objective: To determine the maximum tolerated dose (MTD), toxicity and activity of combined weekly paclitaxel and capecitabine in patients with metastatic breast cancer. Methods: Sixteen patients with metastatic breast cancer, of whom 15 were evaluable for toxicity and response, were enrolled in 7 Swiss centers. Paclitaxel 80 mg/m2 was given intravenously on days 1, 8 and 15. Capecitabine was administered orally on days 1 through 14 using five different dose levels. Both drugs were given in a 21-day schedule. Results: Capecitabine could be administered at doses commonly used for the drug as a single agent, i.e. 1,250 mg/m2 twice daily in combination with weekly paclitaxel. Hematological and other toxicities did not appear to be dose-limiting; however, significant skin and nail toxicities were observed. A response or stable disease was observed in 87% of patients [13/15; exact 95% confidence interval (CI) 60–98%], with 2 complete responses, 4 partial responses (overall response rate 40%, exact 95% CI 16–68%) and 7 patients with stable disease for at least 9 weeks. Conclusion: The phase I evaluation of capecitabine in combination with fixed-dose weekly paclitaxel did not allow the definition of an MTD of capecitabine based on the predefined criteria. Instead, the dose for the phase II evaluation was determined based on the occurrence of toxicity in later courses and on experience with other regimens containing capecitabine. Capecitabine (1,000 mg/m2 twice daily, days 1–14, every 3 weeks) with paclitaxel (80 mg/m2 weekly) is a promising combination for advanced breast cancer now being investigated in a phase II trial.