Paclitaxel and recombinant human granulocyte colony-stimulating factor as initial chemotherapy for metastatic breast cancer

Purpose: A phase II study of Taxol (paclitaxel; Bristol-Myers Squibb Co, Princeton, NJ) as initial chemotherapy for metastatic breast cancer was conducted. Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was used to ameliorate myelosuppression, the anticipated dose-limiting toxicity. Patients and Methods: Twenty-eight patients with bidimensionally measurable breast cancer who had not received prior chemotherapy for metastatic disease were treated. Taxol was administered at 250 mg/m² as a continuous 24-hour intravenous (IV) infusion every 21 days. rhG-CSF was administered at 5 μg/kg/d subcutaneously on days 3 through 10. Results: Objective responses were observed in 16 of 26 assessable patients (62%; 95% confidence interval, 41% to 80%). There were three (12%) complete responses (CRs) and 13 (50%) partial responses (PRs). Ten of 16 patients (63%) who had received prior adjuvant chemotherapy responded, which included one CR and four PRs among eight patients who had received prior doxorubicin-centaining therapy. Responses were observed in all sites of metastatic disease. The median time to first objective response was 5 weeks (range, 1 to 14). Administration of rhG-CSF was associated with a short duration of neutropenia (median, 2 days with absolute neutrophil count < 500 cells/μL). Eight of 26 patients (31%) who received more than one course received subsequent therapy without dose reduction. One hundred seventy-eight cycles of treatment were administered, with a median of six cycles per patient (range, one to 19). Eight courses (4.5%) were associated with admissions for neutropenic fever. Twenty-two patients (79%) did not require admission for neutropenic fever. Treatment was well tolerated. Adverse effects included generalized alopecia in all patients. Myalgias, arthralgias, and peripheral neuropathy were mild. No hypersensitivity reactions and no cardiac toxicity were observed. Conclusion: Taxol is highly active as initial chemotherapy for metastatic breast cancer. Administration of rhG-CSF reduced the incidence, depth, and duration of neutropenia, compared with published prior experience. Further studies of Taxol in breast cancer, including combinations with other active agents, are clearly warranted.