Abstract B206: FG-3019, an anti-CTGF antibody, attenuates tumor invasion, delays tumor growth, and prolongs survival alone and in combination with radiation in an orthotopic glioma model.
Authors: Roehrich Manuel , Zhang Mengxian , Capper David , Wirkner Ute , Trinh Thuy , Jenne Juergen , Debus Juergen , Timke Carmen , Lipson Kenneth E. , Huber Peter E. 
Published: June 2012

Objective: Despite progress in understanding molecular changes in glioblastoma multiforme (GBM), it remains a cancer with poor prognosis in need of better therapy. Pathological features of GBM are explosive growth, angiogenesis and its unique diffuse, infiltrative growth pattern. There is a consensus that cell-matrix-interactions play a pivotal role for infiltrative growth. Connective tissue growth factor (CTGF) is a matricellular protein that is involved in many pathological processes including tumorigenesis and invasion. CTGF modulates cell-matrix-interactions that may allow glioma cells to invade brain parenchyma, degrade the extracellular matrix (ECM), and enhance proliferation and angiogenesis in GBM. High CTGF-expression levels have been reported to correlate with tumor grade, invasiveness and poor patient survival. Here the effects of a human monoclonal anti-CTGF-antibody (FG-3019) were investigated alone and in combination with irradiation in vitro and in vivo in an orthotopic glioma model in mice.

Methods and materials: In vitro studies were performed with two established human glioma cell lines, U87MG and T98G, as well as with primary isolated human glioblastoma cancer stem-like cells (CSLCs) cells. The effects of FG-3019 alone and in combination with photon irradiation (6 MV Linac) on clonogenic survival, proliferation, migration, neurosphere formation, and limiting dilution were determined. RNA was isolated from CSLCs and gene expression changes were examined after different treatments using micro-arrays and RT-PCR. In vivo, CSLCs were subcultured as neurospheres and stereotactically implanted into brains of SCID-beige mice. Mice brains were treated with 7Gy single dose radiation +/− FG-3019. The treatment effects were assessed by MRI, survival time and histology.

Results: Tumor growth delay in the orthotopic tumor model resulted from treatment with radiation or FG-3019 alone, which was significantly enhanced by combined treatment. Similarly, animal survival was prolonged by each monotherapy and significantly enhanced by the combination. Histology showed that FG-3019 significantly reduced constitutive and radiation-induced tumor invasion into the brain parenchyma. FG-3019 also reduced intracellular CTGF expression, glioma cell proliferation, deposition of different types of collagen and reduced microvessel density. FG-3019 also reduced expression of Nestin and the stem cell marker SOX-2. In vitro, FG-3019 and irradiation reduced clonogenicity, proliferation and migration of U87MG, T98G and CSLCs, which was enhanced by the combination. Gene expression analysis revealed that FG-3019 down regulated tumorigenesis- and tumor-invasion-related genes.

Conclusions: The human monoclonal CTGF antibody, FG-3019, shows remarkable anti-tumorigenic and anti-invasive effects in vitro and in vivo in a primary human glioblastoma model growing orthotopically in mice. Our results indicate that FG-3019 alone and in combination with radiotherapy is a promising approach for clinical translation in humans.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B206.