Abstract 5057: HuGAL-F2, a humanized monoclonal antibody to Fibroblast Growth Factor 2, effectively inhibits the growth of hepatocellular carcinoma xenografts

FGF2 (also known as basic FGF; bFGF) is a potent mitogenic and angiogenic growth factor believed to play a role in various tumors, especially hepatocellular carcinoma (HCC). In this study, we explored the therapeutic potential of the HuGAL-F2 humanized monoclonal antibody (mAb) derived from our neutralizing anti-FGF2 mAb, GAL-F2. The GAL-F2 mAb was previously shown to recognize a unique epitope on human FGF2 in a competitive binding assay with various other anti-FGF2 mAbs. By testing several FGF2-FGF1 chimeric proteins followed by alanine scanning mutagenesis of FGF2, we demonstrated that FGF2 residues F40 and M151 are critical for GAL-F2 binding and that residues R31, Y33, K55 and S152 are also part of the epitope. Using well-established humanization techniques, GAL-F2 was humanized to create HuGAL-F2, which binds FGF2 with at least as high affinity as GAL-F2. HuGAL-F2 also had similar activity to GAL-F2 in various bioassays such as inhibition of FGF2-induced proliferation of Mv 1 Lu epithelial cells and HUVEC cells. Hepatomas are characterized by neovascularization, and angiogenesis plays a key role in their growth. Thus, we determined the levels of two angiogenic factors, FGF2 and VEGF, secreted from several HCC cell lines (HEP-G2, HLE, HLF, SK-HEP-1, and SMMC-7721) using ELISA. All these cell lines secreted significant levels of FGF2 and VEGF. To demonstrate that FGF2 indeed plays an important role in HCC tumor growth and to investigate the therapeutic potential of HuGAL-F2, we tested the efficacy of HuGAL-F2 in xenograft tumor models of the HCC lines, SMMC-7721 and HEP-G2. HuGAL-F2, administered i.p. at 5 mg/kg twice per week, significantly inhibited the growth of established xenografts of both these cell lines. Moreover, in the HEP-G2 model, GAL-F2 and HuGAL-F2 were equally effective as sorafenib (Nexavar) and the A4.6.1 anti-VEGF mouse precursor mAb of bevacizumab (Avastin) and had strong additive activity with each of these agents. We conclude that FGF2 is a promising molecular target, and that HuGAL-F2 is a viable clinical candidate for the treatment of HCC and possibly other cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5057. doi:10.1158/1538-7445.AM2011-5057