PACLITAXEL AS 2ND AND SUBSEQUENT THERAPY FOR METASTATIC BREAST-CANCER - ACTIVITY INDEPENDENT OF PRIOR ANTHRACYCLINE RESPONSE

Purpose: Two phase II clinical trials were performed to determine efficacy and tolerability of paclitaxel (Taxol; Bristol-Myers Squibb Co, Wallingford, CT) and granulocyte colony-stimulating factor ([G-CSF] Neupogen; Amgen, Inc, Thousand Oaks, CA) as second or subsequent therapy for metastotic breast cancer, Patients and Methods: paclitaxel plus G-CSF was administered as a second stage IV regimen to 25 patients with metastatic breast cancer at a dose of 250 mg/m(2) intravenously over 24 hours. Fifty-two patients received paclitaxel plus G-CSF at 200 mg/m(2) os a third or subsequent regimen (no restriction on number of prior regimens or on prior high-dose chemotherapy). All patients herd received prior anthracycline treatment, and ultimately had progressive bidimensionally measurable disease. Results: Twenty-five of 76 patients (32.8%) had a major objective response (95% confidence interval [CI], 14% to 37%). The median duration of response was 7 months (range, 1 to 20+), Responses were as likely in patients with disease demonstrated to be unresponsive to anthracycline, ie, de novo resistance (11 of 37, or 30%) as in those with disease that once exhibited anthracycline sensitivity, ie, acquired resistance, (10 of 31, or 32%). G-CSF administration was associated with febrile neutropenic episodes in 36 of 402 cycles (9%) in 16 of 76 patients (21%). Conclusion: Paclitaxel's clinically significant activity against metastatic breast cancer extends to patients with many prior chemotherapy regimens. The lock of impact of prior doxorubicin therapy on the likelihood of subsequent response to paclitaxel suggests an important role for this agent in the treatment of refractory metastatic breast cancer. (C) 1995 by American Society of Clinical Oncology.