Background: Anthracyclines are the most active cytostatic agents in patients with metastatic breast cancer. Drug resistance and dose intensity are relevant issues in the treatment of cancer.
Methods: A randomized phase II study in 51 patients with advanced progressive metastatic breast cancer was performed. Twenty-six were treated with epirubicin (EPI) 120 mg/m2 i.v. bolus injection divided over three days combined with a daily dose of 480 mg verapamil (VPL) orally administered one day before and during EPI. Twenty-five patients received the same dose and schedule of EPI without VPL. Evaluation of response was carried out after three 21-day cycles. Study endpoints were objective response rate and overall survival.
Results: Among the 24 evaluable patients treated with EPI+VPL 1 CR (4%), 7 PR (29%), 9 NC (38%) and 7 PD (29%) were observed. Two patients were excluded because of toxicity. Among the 24 evaluable patients treated with EPI alone 8 PR (28%), 6 NC (24%) and 10 PD (40%) were observed, and one patient was excluded because of toxicity. Myelotoxicity was the major side effect followed by alopecia, stomatitis/mucositis and nausea. The patient group treated with VPL had lower blood pressure levels during therapy, with complete normalization after discontinuation of VPL. The median overall survival times were similar: 7.4 month in the EPI group and 8.9 month in the EPI+VPL group.
Conclusion: In both treatment groups the objective response rate was about 30% and the overall survival rates were also the same. No clinical relevance could be demonstrated for the hypothesized resistance modifying action of VPL. Furthermore, VPL did not increase the toxicity of EPI.