Taxanes have been established in the treatment of metastatic breast cancer, and two presentations at the 20th Annual San Antonio Breast Cancer Symposium provide additional data to more clearly delineate the indications and potential use of these agents.
Dr. John Crown (see page 2) reported the results of the TAX-303 trial comparing docetaxel(Drug information on docetaxel) (Taxotere) at 100 mg/m2 with doxorubicin(Drug information on doxorubicin) at 75 mg/m2. The overall response rate for docetaxel was 48%, versus 33% for doxorubicin in 300 randomized patients, demonstrating a statistically significant higher response rate. Responses appeared to be more rapid for the docetaxel-treated patients. There was no difference in time to progression.
The docetaxel response rate was similar to that reported in previous phase II studies: the doxorubicin rate was similar to that in other randomized trials.
Most patients had previous alkylator therapy, but no patients had prior taxane or anthracycline treatment, and half the patients were chemotherapy-resistant. The toxicity profile was more favorable for docetaxel versus doxorubicin.
Another exciting study was presented by Dr. Hans-Joachim Luck (see page 3) evaluating the role of weekly paclitaxel(Drug information on paclitaxel) (Taxol) in heavily pretreated metastatic breast cancer patients. He reported that 15 of 41 patients had a partial response; 30% of the patients had received prior taxane-based therapy and 10 had received both an anthracycline and a taxane. Not only did he find a significant response rate, but this regimen was well tolerated without severe neutropenia.
Dr. Lucks findings confirm reports of high activity for weekly paclitaxel in heavily pretreated patients presented at ASCO 1997. These results likely reflect overall time of cellular exposure to a drug with schedule-dependent pharmacokinetics. This offers a tolerable, palliative approach to the management of heavily pretreated advanced breast cancer patients.
These reports of single-agent taxane use show that they are extremely active, and future clinical trials with these agents in combination therapy and in the adjuvant setting are currently ongoing.