Effect of Rho/ROCK pathway inhibition on metastasis-free and overall survival in biomarker selected, orthotopic, patient-derived models of pancreatic cancer.

Abstract

e15759 Background: PC is a highly lethal disease which metastasises early. The sequencing efforts of the Australian Pancreatic Cancer Genome Initiative (APGI) identified ROCK-1 as a target of interest. The Rho/ROCK pathway is essential in cellular movement, metastasis, vasculogenesis and stromal signaling. Fasudil (F) is a ROCK inhibitor which has been shown to be safe for human use. Using unique, patient derived models, we have previously shown that F plus gemcitabine (G) does not reduce cellular proliferation in vitro but reduces tumour size and improves overall survival (OS) in subcutaneous patient-derived xenografts (PDX). However, PDXs are critisised for not fully recapitulating the human condition. Here we aimed to generate a patient-derived orthotopic xenograft (O-PDX) which could be used to assess the effects of F + G on metastasis formation and OS. Methods: One patient-derived cell line (PDCL) was labled with firefly luciferase. This was injected into the pancreas of NOD/Shi- scid/IL-2Rγnull (NSG) mice to generate the O-PDX model. The O-PDX was imaged weekly with the IVIS imaging system. The O-PDXs were treated with saline control (S) (n = 8), gemcitabine (G) (n = 10) fasudil (F) (n = 6) or gemcitabine + fasudil (GF) (n = 10). Mice were culled once radiographic or clinical evidence of ascites was detected. Metastasis free (MFS) and OS were recorded. Vessel quantification was performed via CD-31 staining. Results: Metastases seen (spleen, liver, lung, ovary) on imaging were confirmed using GFP stains on immunohistochemistry. F prolonged MFS but not OS when compared with S. GF significantly prolonged MFS (33.5 versus 43 days; p = 0.0339) and OS (51.5 versus 64 days; p = 0.0035). CD-31 staining showed that treatment with F resulted in increased vascularity in the liver metastases and normal liver tissue but not in the pancreas tumour. Conclusions: The addition of Fasudil to gemcitabine improves MFS and OS in an orthotopic model of PC and is a promising new therapeutic option. The increase in vascularity of the metastases and normal liver tissue suggest that changes in vascularity are important and may result in improved delivery of gemcitabine.