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 effi cacy and tolerability of paclitaxel (Taxol; Bristol-Myers Squibb Co, W allingford, CT) and granulocyte colony-stimulating factor ([G-CSF] Neu pogen; 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 2 4 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 prio r regimens or on prior high-dose chemotherapy). All patients herd rece ived prior anthracycline treatment, and ultimately had progressive bid imensionally measurable disease. Results: Twenty-five of 76 patients ( 32.8%) had a major objective response (95% confidence interval [CI], 1 4% to 37%). The median duration of response was 7 months (range, 1 to 20+), Responses were as likely in patients with disease demonstrated t o be unresponsive to anthracycline, ie, de novo resistance (11 of 37, or 30%) as in those with disease that once exhibited anthracycline sen sitivity, ie, acquired resistance, (10 of 31, or 32%). G-CSF administr ation was associated with febrile neutropenic episodes in 36 of 402 cy cles (9%) in 16 of 76 patients (21%). Conclusion: Paclitaxel's clinica lly significant activity against metastatic breast cancer extends to p atients with many prior chemotherapy regimens. The lock of impact of p rior doxorubicin therapy on the likelihood of subsequent response to p aclitaxel suggests an important role for this agent in the treatment o f refractory metastatic breast cancer. (C) 1995 by American Society of Clinical Oncology.