Abstract 1385: Fusion protein containing RGD-endostatin and human Fc of IgG4improves anti-angiogenic and anti-tumor activity

Abstract

Abstract Inhibiting angiogenesis is a promising strategy for cancer therapy. Endostatin, a C-terminal fragment of collagen XV[[Unsupported Character - Ш]], is an endogenous inhibitor of angiogenesis. We have earlier shown that addition of integrin-targeting sequences to a mutant endostain (P125A-endo) improved localization to tumor vasculature. In the present study, we investigated whether genetically fusing endostatin to Fc region of human IgG can prolong circulatory half-life and improve anti-tumor activity. Two types of constructs were made: a) RGD-endostatin-Fc and b) Endostatin-RGD-Fc. The location of the RGD moiety was either placed at the NH2-terminus or between the carboxyl terminus of endostatin and Fc. Both constructs were expressed in HEK-293 cells and purified using affinity chromatography. Our results show the biological activity of endostatin was significantly enhanced by linking to the Fc region of IgG when compared to P125A-endostatin expressed in yeast. Both RGD-Endo-Fc and Endo-RGD-Fc were able to bind endothelial cells very efficiently and inhibited endothelial cells proliferation, migration in vitro and angiogenesis in vivo. We then investigated the ability of the fusion protein to inhibit ovarian cancer growth in a xenograft model. Once a week administration of the fusion protein into mice bearing established ovarian tumors inhibited tumor growth and increased their survival. Anti-tumor activity of the fusion protein was comparable to Bevacizumab-mediated suppression of tumor growth. Furthermore, when mice were treated with a combination of the fusion protein and Bevacizumab, more than additive inhibition of tumor growth was observed. These data suggest that fusion with Fc-fragment can improve the anti-angiogenic and anti-tumor activity of endostatin. Moreover, our results support a strategy to combine two anti-angiogenic reagents such as anti-VEGF antibody and endostatin-Fc fusion protein to additively inhibit ovarian cancer growth. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1385.