Abstract A59: Block/homo polyplex micelle-based GM-CSF gene therapy via intraperitoneal administration elicits antitumor immunity against peritoneal dissemination and exhibits safety potentials in mice and monkeys.

Abstract

Abstract A block/homo-mixed polyplex micelle, comprising of cationic homo polymer: {N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} P[Asp(DET)] and block copolymer: polyethylene glycol (PEG) -P[Asp(DET)], has been reported to exhibit the efficient transgene expression in vivo by intratracheal and systemic administration. In the present study, we investigated the potential of immunogene therapy by intraperitoneal (i.p.) administration of block/homo polyplex micelles for peritoneal dissemination. For evaluation of transgene expression in vivo, block/homo polyplex micelles showed 12-fold higher level in luciferase expression evaluated by bioluminescence imaging system at 24 h after the i.p. administration compared with block polyplex micelles in nude mice bearing peritoneal dissemination. The distribution of polyplex micelles in tumor nodules was similarly present for both polyplex micelles, where the intracellular uptake of plasmid DNA was detected for block/home polyplex micelles but little for block polyplex micelles. The i.p. administration of block/homo polyplex micelles encapsulating granulocyte macrophage colony stimulating factor (GM-CSF) gene elicited GM-CSF expression dominantly in tumors and less in normal organs (liver and spleen), inhibited the tumor growth and prolonged survival rate for the mice harboring disseminated pancreatic cancer more significantly compared with the mock. The antitumor effect of GM-CSF gene therapy was mediated via the activation of natural killer cells. For safety evaluation, block/homo polyplex micelles indicated almost no adverse events for patho-physical findings and blood examinations in mice and cynomolgus monkeys, although slight increases in serum fibrinogen were observed in the monkey model. In conclusion, block/homo polyplex micelle-based immunogene therapy via i.p. administration may be a safe and effective approach for suppressing intractable peritoneal dissemination. Citation Format: Masahiro Ohgidani, Koichi Furugaki, Shinkai Kentaro, Yumi Kunisawa, Keiji Itaka, Kazunori Kataoka, Kenji Nakano. Block/homo polyplex micelle-based GM-CSF gene therapy via intraperitoneal administration elicits antitumor immunity against peritoneal dissemination and exhibits safety potentials in mice and monkeys. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A59.