Abstract A108: TAS-115, a VEGFR/MET-targeted kinase inhibitor, potently suppresses HGF-induced aggressive bone and systemic metastasis in HGF knock-in mice bearing UM-UC-3 bladder tumors

Abstract

Abstract Background: Invasive bladder cancer frequently shows bone and systemic metastasis. Thus, development of a drug that is effective not only against the primary lesion but also the metastatic lesions is needed for therapy of bladder cancer. The expression level of hepatocyte growth factor (HGF) is high in invasive bladder cancer patients and associated with poor outcomes. Moreover, several recent clinical reports show that HGF receptor (MET) expression level was related to cancer grade, stage, tumor size, and poor prognosis in invasive bladder cancer patients. Because HGF-MET signaling has shown a species difference between humans and mice, the usual human cancer xenotransplantation models using nude mice are inadequate to evaluate the effect of agents against tumor growth and metastasis driven by hHGF-MET paracrine signaling. Thus, hHGF knock-in (hHGF KI) mice were generated, and the antitumor efficacy of TAS-115, a MET/VEGFR-targeted kinase inhibitor, was evaluated in a systemic metastasis model of bladder cancer. Material and Methods: A luciferase-transfected human bladder cancer cell line (UM-UC-3-luc) was established. Cell proliferation, invasion, and gene expression analyses were conducted in UM-UC-3-luc after HGF stimulation using Cell titer Glo, a migration assay kit, and DNA array analyses. In the in vivo metastasis model, UM-UC-3-luc cells were injected into the left ventricular cavity of hHGF KI mice. Luciferase activity was measured under deep anesthesia once a week as an index of tumor growth. TAS-115 was administered orally once daily for 4 weeks, when photons emitted from tumor-transplanted regions reached the order of 107. Results: In vitro, HGF significantly enhanced proliferation and invasion of UM-UC-3-luc cells through MET activation. Based on DNA array analyses, several tumor metastasis and invasion-related genes (MMPs, chemokines, transcription factors, and phosphatases) were changed in UM-UC-3-luc cells after HGF stimulation. TAS-115 completely inhibited HGF-driven proliferation and invasion activity in UM-UC-3-luc cells and blocked HGF-induced expression changes of tumor metastasis and invasion-related genes in in vivo xenograft models. Tumorigenicity and metastasis of UM-UC-3-luc cells showed approximately 60% increase in hHGF KI mice compared with WT mice. The major metastatic sites were lower jaw bone, adrenal gland, lymph node, and ovary. Tumor metastasis-related genes in UM-UC-3-luc cell-bearing hHGF KI mice were also changed, as in the in vitro experiments. TAS-115 suppressed >80% of systemic metastasis of UM-UC-3-luc cells in both hHGF KI and WT mice without severe body weight loss. Notably, the more aggressive metastasis of UM-UC-3-luc cells in hHGF KI mice was clearly inhibited by TAS-115 treatment. TAS-115 inhibited phosphorylation of MET and regulated tumor metastasis-related gene expression in metastasized tumor tissue. Conclusions:HGF provided a more aggressive phenotype related to tumor progression to UM-UC-3-luc cells in this in vivo models. TAS-115, a VEGFR/MET-targeted kinase inhibitor, significantly suppressed tumor progression and systemic metastasis in UM-UC-3-luc cell-bearing hHGF KI mice. TAS-115 appears to be a novel therapeutic strategy for patients with advanced bladder cancer. Citation Format: Yukari Yamada, Hidenori Fujita, Yayoi Fujioka, Naomoto Harada, Akihiro Hashimoto, Tomonori Haruma, Shingo Tsuzi, Ryouto Fujita, Kenichi Matsuo, Teruhiro Utsugi, Kazuhiko Yonekura. TAS-115, a VEGFR/MET-targeted kinase inhibitor, potently suppresses HGF-induced aggressive bone and systemic metastasis in HGF knock-in mice bearing UM-UC-3 bladder tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A108.