Cisplatinum-Based Alternating Non-Cross-Resistant Chemotherapy as a First-Line Treatment in Metastatic Breast Cancer. A Phase II Study
Exposure to multiple non-cross-resistant drugs should increase cell kill and the chance of achieving more complete and partial responses. Our earlier study in breast cancer showed that second-line CAP (cyclophosphamide, adriamycin, cis-platinum) treatment was not cross-resistant to the CMFVP (cyclophosphamide, methotrexate, 5-fluorouracil, vincristine, prednisolone) regimen and produced a 51% response rate. These facts initiated a phase II study which used an alternating CMFVP/ CAP regimen. Altogether, 49 patients entered the study and 45 were evaluated (> 2 cycles). The CMFVP regimen consisted of cyclophosphamide (200 mg/m2 on days 1, 2, 3, 4 and 5), methotrexate (30 mg/m2 on days 2 and 4), 5-fluorouracil (500 mg/m2 on days 1, 3 and 5), vincristine (1.4 mg/m2 on days 1 and 5), and prednisolone (40 mg p.o. on days 1-5), and was alternated with the CAP schedule (300 mg/m2 cyclophosphamide on days 1, 3 and 5, 50 mg/m2 adriamycin on day 1, and 30 mg/m2 cis-platinum on days 1, 3 and 5). Overall response was high, and 37 patients out of 45 responded (82%), with a 28% CR rate (13/45). A particularly high response rate was observed in soft tissues (86%, 18/21) and visceral organs (84%, 16/19). Only 1 patient progressed (3%). The duration of remission was 4-21+ months (median, 12 months). Six of 13 CR patients were still disease free 15 months after the treatment was stopped. The duration of survival was 5-25+ months (median, 15+ months). Toxicity was moderate (myelosuppression in 53% of patients, mainly grade I-II; stomatitis in 11%, except for 100% alopecia and 90% nausea and vomiting). One drug-related death (bone marrow aplasia) was recorded. The high antitumorigenic activity of the alternating regimen used is encouraging and may call for a randomized study for the ultimate evaluation of this treatment approach.