Dose intensification of chemotherapy in advanced breast cancer: a feasibility phase II study

Dose intensification of chemotherapy is associated with increased response rates in advanced breast cancer. Achievement of dose incrementation is usually limited by drug-dependent bone marrow toxicity. The recent availability of recombinant human colony-stimulating factors (CSFs) have made it possible to evaluate their potential in ameliorating chemotherapy-induced myelosuppression. The aim of this study was to evaluate tolerability and effectiveness of an intensified mitoxantrone, methotrexate and mitomycin-C (3M) regimen, given with G-CSF support in patients with advanced breast cancer (ABC).

Twenty-eight eligible patients with advanced breast cancer were treated with mitomycin -C (7 mg/sqm i.v. every 4 weeks), methotrexate (35 mg/sqm i.v.) and mitoxantrone (7 mg/sqm i.v. every 2 weeks) for 6 cycles. Recombinant human granulocyte colony-stimulating factor (r-HuG-CSF, Filgrastim) (5 micrograms/kg/day) was given subcutaneously from day 2 to day 12 after each chemotherapy administration to prevent leukopenia.

Of the 27 evaluable patients, 4 had complete response and 14 achieved partial response; the overall response rate was 63% (95% CI; 46.8%-82.2%). The median duration of response was 8 months (range, 4-13+). Chemotherapy-related toxicity was mild: only 3 out of 163 courses had to be postponed due to myelotoxicity.

The 3M regimen given at 2- week intervals is a feasible, active and well toleratel treatment in patients not previously treated for metastatic breast cancer.