Abstract B67: Induction of tumor hypoxia synergises with inhibitors of tumor metabolic and angiogenic adaptive responses to suppress tumor growth and enhance host survival

• Published in: Molecular cancer therapeutics Vol. 12; no. 11_Supplement; p. B67
• Main Authors: Inglis, Daniel J., Lavranos, Tina C., Beaumont, Donna M., Leske, Annabell F., Brown, Chloe K., Kremmidiotis, Gabriel
• Format: Journal Article
• Language: English
• Published: 01-11-2013
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.TARG-13-B67

BNC105 is a compound that exerts an anti-cancer action through selective destruction of tumor blood vessels. A single IV dose of BNC105 causes a very high degree of tumor hypoxia leading to >95% necrosis in rodent models.
Despite the dramatic tumor necrosis, tumor recovery becomes evident by day 2 following BNC105 treatment. We conducted immunohistochemical, in vitro and in vivo studies to identify the cellular and molecular basis driving tumor recovery from the significant vascular destruction caused by BNC105. Renal cancer cell lines treated with BNC105 exhibited increased expression of HIFα, VEGFA and increased phosphorylation of mTOR and 4EBP1. These observations led us to investigate the potential therapeutic benefit of combining BNC105 with agents inhibiting the signalling pathways corresponding to these proteins. We hypothesised that targeting the mTOR pathway and VEGF driven revascularisation of tumors with the mTOR inhibitor Everolimus or pan-VEGFR inhibitor Pazopanib in combination with BNC105 would lead to greater therapeutic benefit. A panel of renal cancer cell lines, including VHL mutant and VHL wild type, were shown under both normoxic and hypoxic conditions to express high levels of VEGFA. Culturing these cell lines with the mTOR inhibitor Everolimus significantly reduced VEGFA expression and decreased phosphorylation of p70S6K. These findings demonstrate that Everolimus effectively curtails VEGFA signalling and is appropriate to combine with BNC105 therapy. We tested the potential combinatorial benefit of BNC105 + Everolimus in vivo using the mouse renal cancer cell line RENCA. Tumor Growth Inhibition (TGI) with Everolimus alone was 46% and BNC105 alone 18%. The BNC105 + Everolimus combination treatment resulted in 73% TGI and was statistically significant compared to the inhibition seen with the monotherapies (p<0.05). Similarly in a human renal carcinoma cell line xenograft (Caki-1), TGI with Everolimus alone was 23% and BNC105 25% alone and in combination increased to 46% displaying additive benefit. The potential benefit of combining BNC105 with the pan-VEGFR inhibitor Pazopanib was also investigated. We similarly hypothesised that tumor recovery from the BNC105 induced hypoxia/necrosis insult could be curtailed through inhibition of VEGF receptors. Treatment of RENCA tumors with BNC105 alone resulted in 21% TGI and Pazopanib alone 19%. In combination the TGI was 46%. Furthermore, survival was significantly increased (p=0.0001) than animals treated with monotherapies. These data demonstrate that BNC105 can be combined with Everolimus or Pazopanib, to yield greater anti-tumor efficacy in renal cancer. A randomised Phase II trial evaluating the potential benefit of combining BNC105 with Everolimus in patients with metastatic renal cancer has finished accrual and expected to yield results in the first half of 2014.
Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B67.
Citation Format: Daniel J. Inglis, Tina C. Lavranos, Donna M. Beaumont, Annabell F. Leske, Chloe K. Brown, Gabriel Kremmidiotis. Induction of tumor hypoxia synergises with inhibitors of tumor metabolic and angiogenic adaptive responses to suppress tumor growth and enhance host survival. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B67.