Purpose: On the basis of stimulating data on animals reporting that weekly regimens of zoledronic acid (ZA) were effective in reducing skeletal tumor burden, we designed a study on humans to investigate the potential antiangiogenic role of a weekly low-dose therapy with ZA in patients with malignancies.
Experimental design: Twenty-six consecutive patients with advanced solid cancer and bone metastases received 1 mg of ZA every week for four times (days 1, 7, 14, and 21) followed by 4 mg of ZA with a standard 28-day schedule repeated thrice (days 28, 56, and 84). Patients were prospectively evaluated for circulating levels of vascular endothelial growth factor (VEGF) just before the beginning of drug infusion (0) and again at 7, 14, 21, 28, 56, and 84 days after the first ZA infusion.
Results: The median VEGF basal value showed an early statistically significant (P = 0.038) decrease 7 days after the first 1-mg infusion of ZA. This effect on VEGF-circulating levels persisted also after the following 1-mg infusions at 14 (P = 0.002), 21 (P = 0.001), and 28 days (P = 0.008). Interestingly, the decrease of VEGF-circulating levels persisted also at each programmed time point during the second phase of the study (ZA 4 mg every 4 weeks). No significant differences were recorded in platelet levels, WBC count, or hemoglobin concentration before and after each ZA infusion.
Conclusions: In the present study, we report that a repeated low-dose therapy with ZA is able to induce an early significant and long-lasting decrease of VEGF levels in cancer patients.