The Bisphosphonate Zoledronic Acid Reduces Experimental Neuroblastoma Growth by Interference with Tumor Angiogenesis

Background: Zoledronic acid is a new member of the bisphosphonate (BP) class of compounds, a family of closely related synthetic molecules originally derived from the naturally occurring pyrophosphate. These compounds that are potent inhibitors of bone resorption, have been shown to reduce the growth of several cancer cell lines in vitro, and can act as inhibitors of angiogenesis. The angiogenesis inhibitor TNP-470, a synthetic analogue of the fungal antibiotic fumagillin, has been shown to inhibit the growth of multiple tumors in vivo, and is currently in Phase H clinical trials for cancer. Materials and Methods: The effects of daily subcutaneous (s.c.) administration of zoledronic acid (0.1 mg/kg) were compared with those of TNP-470 (15 mg/kg/day and 30 mg/kg every other day, s.c.) in a nude mouse xenograft model for the childhood cancer, neuroblastoma (NB). Results: Zoledronic acid reduced the tumor growth by 33% whereas TNP-470 was less effective and reduced the tumor growth by 26% and 11% for animals treated with 15 mg/kg/day and 30 mg/kg every other day, respectively. Analysis of angiogenesis showed a significant reduction of the number of vessels per grid and in vessel length in all the treatment groups. Conclusion: Zoledronic acid shows tumoristatic and angiostatic properties that might be beneficial in the treatment of solid tumors such as neuroblastoma.