Low-dose oral methotrexate and cyclophosphamide in metastatic breast cancer: antitumor activity and correlation with vascular endothelial growth factor levels.

BACKGROUND: Anticancer chemotherapy is thought to be effective by means of direct cytotoxicity on tumor cells. Alternative mechanisms of efficacy have been ascribed to several common anticancer agents, including cyclophosphamide (CTX), methotrexate (MTX), anthracyclines and taxanes, postulating an antiangiogenic activity. PATIENTS AND METHODS: We evaluated the clinical efficacy and impact on serum vascular endothelial growth factor (VEGF) levels of low-dose oral MTX and CTX in patients with metastatic breast cancer. MTX was administered 2.5 mg bd on days 1 and 2 each week and CTX 50 mg/day administered continuously.
RESULTS: Sixty-four patients were enrolled, 63 were evaluable: Eastern Cooperative Oncology Group (ECOG) performance status 0-1, > or =2 sites of metastatic disease (n = 50 patients), progressive disease at study entry (n = 51), 1 regimen for metastatic disease (n = 32) and > or =2 regimens (n = 20). Among the 63 evaluable patients, there were two complete remissions (CR), 10 partial remissions (PR) for an overall response rate of 19.0% (95% CI 10.2% to 30.9%) and an overall clinical benefit (CR+ PR+ stable disease >24 weeks) of 31.7% (95% CI 20.6% to 44.7%). Grade > or =2 leucopenia was registered in only 13 patients. The median serum VEGF level for the subgroup of patients on treatment for at least 2 months decreased with treatment from 315 pg/ml (95% CI 245 to 435) at baseline to 248 pg/ml (95% CI 205 to 311) at 2 months (P <0.001). Both responders and non-responders showed similar reductions in serum VEGF (P = 0.78). After 6 months patients still on treatment had a median VEGF level of 195 pg/ml (95% CI 96 to 355), which was significantly lower than the median baseline values (P = 0.001).
CONCLUSIONS: Continuously low-dose CTX and MTX is minimally toxic and effective in heavily pretreated breast cancer patients. A drop in VEGF was associated with the treatment and so alternative hypotheses, other than that of direct toxicity on tumor cells, must be favored when trying to explain the anticancer effect.