The Angiogenesis Inhibitor TNP-470 Effectively Inhibits Human Neuroblastoma Xenograft Growth, Especially in the Setting of Subclinical Disease

Tumor vascularity is highly correlated with disease outcome in neuroblastoma. Thus, novel therapeutics that target the vascular endothelium are candidates for incorporation into clinical trials. We therefore examined the effect of TNP-470 on human neuroblastoma growth in mouse models reflecting both clinically evident and minimal disease. Mice were inoculated s.c. or by tail vein injection with 10 7 human neuroblastoma-derived CHP-134 cells and treated with TNP-470 (100 mg/kg/dose s.c. three times a week or by continuous infusion) or saline. Treatment was given as a single agent in established xenografts, 10 days after 450 mg/kg of cyclophosphamide, or 12 h after tumor inoculation. Tumor growth rate was markedly inhibited in mice receiving TNP-470 administered alone both s.c. and by continuous infusion with a treatment to control ratio (T:C) at day 16 of 0.3 ( P < 0.001) and a T:C at day 30 of 0.4 ( P = 0.029) for each dosing method, respectively. TNP-470 also significantly inhibited tumor growth when administered following cyclophosphamide (T:C at day 30 = 0.2, P < 0.001) and inhibited disease establishment when given shortly after xenograft inoculation (T:C at day 30 = 0.1, P < 0.001) or tail vein injection. TNP-470 was shown to directly inhibit angiogenesis by Matrigel assay ( P = .010) and to increase the apoptotic index in treated tumors. These data show that TNP-470 is a potent inhibitor of human neuroblastoma growth rate and tumorigenicity. We speculate that TNP-470 may be a useful adjuvant therapy for high-risk neuroblastoma patients, particularly when used in settings of minimal disease status.