A pilot study of dose intense doxorubicin and cyclophosphamide followed by infusional paclitaxel in high-risk primary breast cancer

We conducted a pilot study of dose dense doxorubicin and cyclophosphamide (AC) combination chemotherapy followed by infusional paclitaxel (T) in primary breast cancer to determine its safety and feasibility. Twenty-two subjects (10 with stage II and ≥4 positive lymph nodes, and 12 with stage III disease) were treated with AC (A 60 mg/m² and C 2000 mg/m²) with filgrastim every 14 days for three cycles followed by infusional paclitaxel (140 mg/m² over 96 h) every 14 days for three cycles. Mean overall cycle length was 15.3 days and mean duration of therapy was 92 days. Dose reductions of C or T were required in 7/132 (5.3%) cycles for mucositis, diarrhea, or failure to recover platelets by day 15. Ninety-five percent of subjects had grade 4 neutropenia and 1 subject had a platelet nadir of <20,000. Actual delivered dose intensity (DI) over six cycles was: A 27 mg/m² per week; C 892 mg/m² per week; T 64 mg/m ² per week (90.6, 89.2, and 91.4% of planned DI, respectively). Average total dose administered was: A 180 mg/m²; C 5880 mg/m ²; T 403 mg/m² (100, 98, and 96% of planned total doses, respectively). Clinical response rate in 10 subjects receiving neoadjuvant therapy was 100% (4 complete response, 6 partial response). Four subjects had a pathologic complete response (three subjects without evidence of malignancy and one subject with ductal carcinoma in situ.) Administration of dose dense AC followed by infusional paclitaxel in 14-day cycles is feasible and this regimen is active in breast cancer.