Abstract 1387: Development of novel antiangiogenic biologics: multifunctional VEGF traps
Authors: Michael Iacovos P. , Sung Hoon Ki , Nagy Andras 
Published: February 2011

Abstract
Current anti-VEGF biologics have been successfully used as therapeutic agents for cancer and age-related macular degeneration (AMD). Since these strategies target VEGF systemically, side effects, long-term toxicities, such as proteinuria and thromboembolic events, and need for frequent eye injections in AMD treatment, prevail. Therefore, the aim of this study was to generate novel anti-VEGF biologics that inhibit VEGF activity specifically at the desired target site.
Two classes of antibody-based recombinant proteins were engineered that simultaneously bind VEGF and either: 1) the extracellular matrix (ECM) or 2) target-site specific antigens. The first subgroup of proteins, “shV-H traps”, is comprised of a Fc domain shortened form of VEGF-trap linked to a sequence of hydrophobic amino acids, with various affinities for heparin sulfate proteoglycans of the ECM, designed to have a short systemic half-life. The second subgroup of molecules, “V-lassos”, is composed of a C-terminus positioned form of VEGF-trap linked to single-chain variable domain antibodies specific for either HER-2 or fibronectin extra domain B (EDB), expressed on tumour cell surfaces or in the vascular bed of solid tumours, respectively.
Recombinant proteins were expressed in transgenic cancer cell lines in a doxycycline inducible manner and were shown to inhibit VEGF activity and also retain the native function of their constituent domains. Specifically, the shV-H traps adhered to the ECM and the HER-2 V-lasso inhibited the proliferation of HER-2 positive cancer cell lines.
Xenograft studies were performed using the aforementioned transgenic cancer cell lines in order to determine the efficacy of shV-H traps and Vlasso. shV-H traps were able to inhibit or delay tumour growth of A-673, Pc-3 and HT-29 xenografts. In contrast to soluble VEGF-trap, sh-VH traps were retained at the tumour site and were undetectable in the circulation. Moreover, sh-VH traps did not cause any of the side-effects observed with soluble VEGF-trap, such as delay of wound healing and regression of trachea blood vessels. Both Vlassos were able to inhibit or delay the tumour growth of SKOV-3 and A-673 xenografts. Furthermore, the transgenic approach for inducible expression indicated that HER-2 Vlasso is more effective compared to anti-HER-2 Ab and VEGF-trap used alone or in combination.
Preliminary results suggest that high recombinant protein levels can be generated via large-scale production in 293F cells, indicating that the new multifunctional VEGF-traps can be produced in large amounts for clinical studies.
These novel classes of anti-angiogenic molecules could potentially be advantageous in a clinical setting. Furthermore, they can be useful in order to further study and understand the mechanisms involved in VEGF inhibition. Finally, similar dual function proteins can be designed for inhibition of other molecules with disease relevance.
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 1387.