Abstract 3108: Gemcitabine nanoparticles showin vitroefficacy in murine pancreatic ductal adenocarcinoma

Our goal is to develop nanotherapeutics for the treatment of pancreatic ductal adenocarcinoma (PC). Squalenoylated Gem (SqGemNPs) and Gem-loaded temperature sensitive liposomes (GemTSLs) were synthesized and the resulting efficacy was compared to that of gemcitabine (Gem) and Abraxane®. Squalenoylation is the conjugation of squalene, a cholesterol precursor, to a drug and enhances in vivo delivery, half-life, and therapeutic efficacy [1]. All particles were evaluated in vitro in both a monolayer and organoid culture of the KrasLSL-G12D/+; Trp53LSL-R172H/+; Pdx-Cre (KPC) model. The organoid culture allows for phenotypic maintenance that is otherwise lost with monolayer culturing [2]. SqGem and Cholesterol-PEG2k co-assembled into SqGemNPs via nanoprecipitation to yield particles of 210 ± 150 nm with 35 wt% Gem. Gem was loaded into TSLs by complexing copper to Gem inside multilamellar liposomes comprised of DPPC:DSPE-PEG2K:DSPC (50:5:15) to yield particles of 110 ± 26 nm with 1.7 wt% Gem. KPC cells were plated as both monolayers and Matrigel™ suspensions and organoid-cultured cells were plated in Matrigel. Cells were incubated with free Gem, SqGemNPs, pre-heated Gem-TSLs, or Abraxane. At 48h, cell survival was assessed using an MTT assay (Invitrogen, Carlsbad, CA). In monolayer-cultured cells, SqGemNPs was the only tested therapeutic to achieve 100% cell death (which occurred at a concentration of 50 uM). All other treatments reached a plateau of efficacy as a function of concentration. Two anticipated trends were confirmed; monolayer-cultured cells were more responsive to all treatments than organoid-cultured cells, and cells plated in Matrigel were less responsive to therapy than those plated as a monolayer. We found that the efficacy of preheated GemTSLs was similar to free Gem in all cell cultures and thus release from the TSLs was validated. In the organoid culture, the IC50 of SqGemNPs was 0.12 ± 0.04 uM compared to 0.19 ± 0.04 uM for free Gem, although both reached a plateau of efficacy at 70% cell death. The efficacy of Abraxane, GemTSLs and Gem plateaued at 45%, 77% and 70% cell death, respectively in organoids. In future studies, two techniques to increase drug availability in PC tumors will be evaluated: SqGemNPs plus high intensity ultrasound ablation, which can increase drug accumulation by 50-fold [3] and GemTSLs plus ultrasound hyperthermia to locally release Gem at a high concentration within the tumor vasculature. 1 Couvreur, P. et al. Nano Lett 6, 2544-2548, doi:10.1021/nl061942q (2006). 2 Boj, S. F. et al. Cell 160, 324-338, doi:10.1016/j.cell.2014.12.021 (2015). 3 Wong, A. W. et al. J Clin Invest 126, 99-111, doi:10.1172/Jci83312 (2016). Citation Format: Samantha T. Tucci, Hamilton Kakwere, Azadeh Kheirolomoom, Jai W. Seo, Elizabeth Ingham, Chang-Il Hwang, Katherine Ferrara. Gemcitabine nanoparticles show in vitro efficacy in murine pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3108. doi:10.1158/1538-7445.AM2017-3108