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Abstract 4060: Discovery and preclinical development of KRAS-targeting siRNA therapeutic modality for the treatment of pancreatic cancer

Pancreatic cancer is the third most common cause of death from cancer in the US. The disease has a poor prognosis with a five-year survival rate under 10%. Mutations in KRAS are driving tumor growth in about 95% of patients with pancreatic cancer. Currently there are no approved drugs that target KRAS. Recently there has been progress targeting a specific mutation, KRAS G12C with small molecules in lung cancer, but this mutation accounts for only 1% of patients with Pancreatic Ductal Adenocarcinoma (PDAC). RNA interference has the potential to directly target KRAS, but delivery to pancreas has been challenging. We have developed a lipid nanoparticle formulation that is able to distribute to pancreatic tumor tissue. The proprietary lipid nanoparticle (LNP) is comprised of an ionizable, non-immunogenic, biodegradable lipid and the composition has been tuned to favor enrichment in pancreatic tumor by screening in orthotopic pancreatic tumor mouse models. A potent siRNA with IC50 in the range of 10pM targeting KRAS directly has been identified and the activity on downstream pathways and kinetics have been demonstrated. Transfection of ND-05-1192 led to more impeded cell growth in pancreatic cancer cells (PANC-1, AsPC-1, Capan-1, SW1990 and BxPC-3) than normal cells (human hepatocyte, pancreatic cells and HUVEC cells). Western blot results demonstrated effective downregulations of key proteins involved in MAPK and PI3K signaling pathways and upregulated activities of proteins involved in apoptotic signaling pathways, such as BIM, caspase 3/7 and cleaved-PARP following inhibition of KRAS protein expression. In vivo biodistribution and tumor cell uptake study results demonstrated that LNP transported ND-05-1192 siRNA molecules to the pancreas site and pancreatic orthotopic tumor tissues with the majority of tumor cells showing LNP product uptake. The application of ND-05-1192/LNP product significantly suppressed tumor growth in PANC-1 and AsPC-1 bioluminescent orthotopic pancreatic xenograft models. Inhibition efficiency revealed by tumor weight and bioluminescent response (BLR) as the treatment end points reached up to 50% in the PANC-1 orthotopic xenografts following once weekly intravenous administration. In the orthotopic AsPC-1 model, the average BLR was significantly reduced in a dose-dependent manner. Additionally, in AsPC-1 orthotopic xenografts, the survival rate of the ND-05-1192/LNP treatment group was significantly prolonged at a 4 mg/kg dose compared to the vehicle control group. In summary, we conclude that ND-05-1192/LNP is delivered to the orthotopic pancreatic tumor and its considerable uptake by tumor cells results in KRAS target downregulation, tumor growth inhibition and overall survival benefit as demonstrated in our orthotopic xenograft models. Citation Format: Zhihong (Julie) OBrien, Li Wang, Cima Cina, Bharat Majeti, James Chu, Xiaoen Wang, Robiel Baclig, James Lin, Jose Ibarra, Dhrubamitra Chatterjee, Jung-Kang Jin, Jean-Pierre Clamme, Jennifer Daniels, Hai Wang, Jens Harborth, Wenbin Ying. Discovery and preclinical development of KRAS-targeting siRNA therapeutic modality for the treatment of pancreatic cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4060.