Abstract 4956: Pharmacological inhibition of Bruton's Tyrosine Kinase (BTK) as a therapy for insulinoma and pancreatic ductal adenocarcinoma.

Abstract

Abstract Myc, a pleiotropic transcription factor that is deregulated and/or over-expressed in most human cancers, instructs multiple extracellular programs that are required to sustain the complex microenvironment needed for tumor maintenance, including remodeling of tumor stroma, angiogenesis and inflammation. We previously showed in a model of pancreatic [[Unsupported Character - Symbol Font β]] cell tumorigenesis that acute Myc activation in vivo triggers rapid recruitment of mast cells to the tumor site and that this is absolutely required for angiogenesis and macroscopic tumor expansion. Moreover, systemic inhibition of mast cell degranulation with sodium cromoglycate induced death of tumor and endothelial cells in established tumors. Hence, mast cells are required both to establish and to maintain the tumors. While this intimates that selective inhibition of mast cell function could be therapeutically efficacious, cromoglycate is not a practical drug for systemic delivery in humans and no other systemic inhibitor of mast cell degranulation has hitherto been available. Ibrutinib is a novel inhibitor of Bruton's tyrosine kinase (Btk) that blocks mast cell degranulation and is currently in clinical trials as a therapy for B cell non-Hodgkin's lymphoma. Here, we show that systemic treatment of insulinoma-bearing mice with Ibrutinib efficiently inhibits Btk, blocks mast cell degranulation and triggers collapse of tumor vasculature and tumor regression. We also show that pancreatic ductal adenocarcinoma (PDAC)-bearing mice treated with Ibrutinib survive longer and present reduced tumor stroma, suggesting that combinatorial therapy with Ibrutinib and standard of care is a feasible therapeutic approach. Conclusions: our data reinforce the notion that mast cell function is required for maintenance of certain tumor types and indicate that the Btk inhibitor Ibrutinib may be useful in treating pancreatic cancer. Citation Format: Daniel Massó-Vallés, Erika Serrano, Jonathan R. Whitfield, Joseph J. Buggy, Nicole M. Sodir, Nesrine I. Affara, Lamorna Brown Swigart, Gerard I. Evan, Laura Soucek. Pharmacological inhibition of Bruton's Tyrosine Kinase (BTK) as a therapy for insulinoma and pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4956. doi:10.1158/1538-7445.AM2013-4956