Abstract 1003: A novel anti-angiogenic compound F16 that inhibits xenograft tumor growth

Recruitment of new blood vessels, commonly referred as tumor angiogenesis, during cancer progression provides an important route by which tumor cells can enter the circulation and cause distant metastasis. Tumor cells that are overexpressing vascular endothelial growth factor (VEGF) can shift the balance towards pro-angiogenic mechanisms to favor aggressive growth and enhanced metastatic potential. In this process binding of VEGF to its receptor is very critical step for triggering kinase activation and trans-phosphorylation that can eventually lead to the activation of a complex signal cascade and completion of angiogenesis. Therefore, interference with the function of the VEGFR has become a promising strategy to inhibit tumor angiogenesis. Through the molecular modeling approach a novel isoindol-amide compound, code named F16, was identified as a potent antagonist for VEGFR. The anti-angiogenic potential of F16 was confirmed through the in vitro angiogenesis assay using HUVEC cells that were grown on ECMatrixTM gel with different concentrations (0 to 10 µM) of F16. Binding assay with fluorokine conjugated VEGF in HUVEC cells proved a strong competitive binding ability for F16 (0.001 to 1.0 µM) with VEGFR in a dose dependent manner. In the whole cell binding assay nearly 95% inhibition of fluorokine conjugated VEGF was observed at 1.0 µM concentration of F16. Also, the western blot analysis showed a strong inhibition of VEGF induced phosphorylation of VEGFR2 by F16 at the same (1.0 µM) concentration in HUVEC cells. Furthermore, In vivo experiments were conducted to confirm the extent of F16 induced tumor growth inhibition in athymic nude mice that were implanted with GI-101A breast tumor xenograft. In these experiments the tumor bearing mice were designated to experimental groups (N = 6/group), namely: Control; F16 (100 mg/kg body weight); Taxol (10 mg/kg body weight); and F16 (100 mg/kg body weight) + Taxol (10 mg/kg body weight). All treatments were given intraperitonealy once in two days for a period of 21 days. Tumor growth was assessed every week using the caliper measurement. In the xenograft mice that were treated with F16 or Taxol alone nearly 65% and 71.5% inhibition of tumor growth was observed, respectively, while combination (F16 + Taxol) treatment showed more than 85.2% inhibition when compared to the untreated controls. Results from our study confirm that F16 inhibits VEGF binding and consequently VEGFR2 phosphorylation to prevent endothelial cell proliferation, migration and sprouting of new capillaries. Our findings so far have fully validated F16 as a promising anti-angiogenic agent. (The Royal Dames of Cancer Research Inc., Ft. Lauderdale, Florida is gratefully acknowledged for their generous financial support). Citation Format: Appu Rathinavelu, Sivanesan Dhandayuthapani. A novel anti-angiogenic compound F16 that inhibits xenograft tumor growth. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1003. doi:10.1158/1538-7445.AM2014-1003