Abstract 577: Systemic delivery of CBT-15G DCLK1-targeted monoclonal antibody dramatically decreases tumorigenesis in a xenograft model of pancreatic cancer
Authors: Weygant Nathaniel , Qu Dongfeng , May Randal , Chandrakesan Parthasarathy , Ge Yang , Ryan Chelsea D. , An Guangyu , Schlosser Michael J. , Bannerman-Menson Edwin , Houchen Courtney W. 
Published: July 2016

Abstract
Introduction
Pancreatic cancer is the 4th leading cause of cancer mortality in the US. Treatments for pancreatic cancer are desperately needed as current drugs lead to little or no improvement in patient survival. Doublecortin-like kinase 1 (DCLK1) marks putative stem cells in colon and pancreatic cancers and regulates important oncogenic processes including epithelial-mesenchymal transition, which supports metastasis. DCLK1's extracellular domain is a novel target for therapeutic monoclonal antibodies (mABs) that has not previously been pursued.
Materials and Methods
Development of a DCLK1-targeted mAB: Balb/c mice were immunized with proprietary KLH-linked peptides targeting the DCLK1 extracellular domain. After immunization, mice were killed and spleens were taken and used to generate hybridoma cell lines, which were subcloned to the monoclonal level. Hybridoma media containing DCLK1-mAB were screened for their ability to bind immunogen peptide and DCLK1 purified protein, and the best clone was selected for further production (CBT-15G). CBT-15G was produced on a large scale in roller bottles, purified using a MEP column, and dialyzed into PBS.
Xenograft study: 0.5×106 SW1990 human pancreatic cancer cells suspend in matrigel were injected into the flanks of 8-week old athymic nude mice and allowed to grow until reaching an average tumor volume of 100 mm3. Xenografts were treated with intraperitoneal CBT-15G mAB or isotype control at 25 mg/kg twice per week for 4 weeks. Tumor volume measurements were taken every other day using calipers. 30 days from the start of injections mice were killed and tumors excised, measured, weighed, and lysed for downstream analysis. Changes in volume and weight were analyzed statistically using Graphpad Prism 6.0.
Results
CBT-15G dramatically decreases tumorigenesis in SW1990 xenografts via a DCLK1-based mechanism of action: Biweekly injections of CBT-15G mAB significantly inhibited SW1990 pancreatic cancer xenograft growth over a period of 4 weeks (p&lt;0.0001 by ANOVA). Excised tumor volume and weights were also significantly different and confirmed these findings. Furthermore, analysis of cell lines treated with CBT-15G and the xenograft tissues confirmed a DCLK1-based mechanism of action.
Conclusion
These findings for the first time demonstrate the systemic in vivo efficacy of DCLK1-targeted mABs against pancreatic cancer. As viable treatments for pancreatic cancer are currently severely lacking, CBT-15G DCLK1-targeted therapy should be investigated further as a potential treatment.
Citation Format: Nathaniel Weygant, Dongfeng Qu, Randal May, Parthasarathy Chandrakesan, Yang Ge, Chelsea D. Ryan, Guangyu An, Michael J. Schlosser, Edwin Bannerman-Menson, Courtney W. Houchen. Systemic delivery of CBT-15G DCLK1-targeted monoclonal antibody dramatically decreases tumorigenesis in a xenograft model of pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 577.