Background: Pancreatic ductal adenocarcinoma (PDA) is an almost uniformly lethal disease. The current treatment for resectable disease consists of surgery and adjuvant gemcitabine therapy. However, for more than 80 percent of the patients with PDA surgery is not an option. For these patients palliative chemotherapy using gemcitabine, or most recently FOLFIRINOX, is considered standard of care. Even with palliative chemotherapy the median overall survival for patients with metastatic PDA is dismal and improved therapeutic strategies are a clear unmet medical need. Heparins may be of interest for the treatment of PDA. They play an important role in tumor progression and metastasis by binding at heparin binding domains, thereby preventing growth factor gradients created along proteoglycan heparan sulfates and thus disrupting signaling. We used a novel heparan sulfate mimetic, M402, which binds to multiple growth factors, adhesion molecules, and chemokines. We previously showed that M402 decreases both epithelial-to-mesynchymal transition and chemotherapy resistance in PDA. Here we further evaluated the underlying mechanisms of M402 in EMT.
Results: We studied the effects of M402 on PDA using a genetically engineered mouse model (GEMM) for PDA (LSL-KRASG12D/+; Trp53 LSL-R172H/flox; pdx-CRE), which recapitulates human PDA. Combination therapy of M402 with gemcitabine significantly prolonged the average survival of the mice when compared to mice treated with gemcitabine monotherapy (87 days versus 78 days) and significantly reduced metastasis and local invasion into the small intestine. These data suggest an effect of M402 on invasiveness and EMT. Gemcitabine treatment increased EMT as determined by staining for E-cadherin and Fsp1 double positive cells. In contrast, M402 treatment resulted in a decrease in E-cadherin and Fsp1 double positive cells in pancreatic tumors. We next sought to determine whether M402 affects cancer cells or stromal cells. In vitro experiments show that cell lines derived from our model respond to M402 by decreasing their invasive behavior in 3D culture and scratch assays. Moreover, we found that M402 augments the gemcitabine effect in vitro. These data suggest that M402 affects both EMT and gemcitabine response. Further identification by whole transcriptome microarray analysis of treated tumors hints towards a role of M402 in affecting multiple signaling pathways involved in the regulation of EMT. These data will undoubtedly lead to better insight into the mechanism of action of M402 and will increase our understanding of the pathways PDA cells use to evade the effects of chemotherapy. M402 is currently being investigated in a phase 1/2 M402 gemcitabine combination study to assess if these findings can be translated into a clinical benefit in pancreatic cancer patients.
Conclusion: These data suggest that M402 reduces acquired chemotherapy resistance in a GEMM for PDA by decreasing EMT.
Citation Format: Ilse Oosterom, Birgit C. Schultes, Chia Lin Chu, Zoya Galcheva-Gargova, Elma Kurtagic, He Zhou, Jay Duffner, Emile E. Voest, David A. Tuveson, Martijn Lolkema. Characterization of effects of M402 on EMT in 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 302. doi:10.1158/1538-7445.AM2013-302