A pilot study of three sequential chemotherapeutic regimens in metastatic breast cancer

The aim of this pilot study was to estimate the toxicity and response rate of an alternating chemotherapeutic program in chemotherapy-naive metastatic breast cancer patients. Treatment consisted of regimen A (given days 1-28): cyclophosphamide 100 mg/m² PO days 1-14, doxorubicin 30 mg/m² i.v. days 1 and 8, and 5-fluorouracil 500 mg/m² i.v. days 1 and 8 (CAF regimen); regimen B (given days 29-56); dibromodulcitol 135 mg/m² p.o. days 30-39, mitoxantrone 9 mg/m² i.v. day 29, and vincristine 1.2 mg/m² i.v. (maximum 2.0 mg) day 29 (DMV regimen); and regimen C (given days 57-84): thiotepa 12 mg/m², doxorubicin 45 mg/m² and vinblastine 4.5 mg/m² all i.v. on day 57. There were 27 eligible patients with a median age of 51 years (range 34-78). On 14 episodes the leukocyte count fell to <1 X 10⁹/L during the first six cycles of treatment (14% of 99 cycles). There were no treatment-related deaths. Common non-life-threatening toxicities included thrombocytopenia, anemia, vomiting, and alopecia. Despite having no drugs in common, the leukocyte and platelet nadirs after CAF correlated with the nadir counts after DMV (r values of 0.6829 and 0.5892, respectively; p = 0.01). Among the 23 patients with measurable and/or evaluable disease there were five complete responses (22%) and nine partial responses (39%), with a median time to treatment failure of 29 weeks. The overall median survival was 19 months.