title: Enhanced anti-tumor efficacy and safety profile of tumor microenvironment-responsive oncolytic adenovirus nanocomplex by systemic administration.
abstract: Oncolytic adenovirus (Ad) holds great promise as a potential gene therapy for cancer. However, intravenously administered Ad may encounter difficulties due to unfavorable host responses, non-specific interactions, and the heterogeneity of the tumor cell population. As an approach to combine the advantages of oncolytic Ad and synthetic polymers and to address the associated difficulties, Ad was physically complexed with a pH-sensitive block copolymer, methoxy poly(ethylene glycol)-b-poly(l-histidine) (mPEG-b-pHis). The in vitro transduction efficiency at an acidic extracellular pH was remarkably enhanced in cancer cells when treated with the Ad expressing green fluorescent protein (GFP) coated with mPEG-b-pHis (c-dE1/GFP) as compared to that of naked Ad (n-dE1/GFP). Time-lapse total internal reflection fluorescence microscopic imaging revealed a significantly enhanced cellular uptake rate of c-dE1/GFP at acidic tumor pH when compared with that at neutral pH or naked cognate Ad (n-dE1/GFP). In addition, c-dE1/GFP remained relatively stable in human serum-containing media, and considerably reduced both the innate and adaptive immune response against Ad. Moreover, the therapeutic efficacy and survival benefit of mPEG-b-pHis-complexed oncolytic Ad (c-H5mT/Luc) by systemic treatment was significantly enhanced compared to that with naked oncolytic Ad (n-H5mT/Luc) in both coxsackie and adenovirus receptor-positive and -negative tumors. Whole-body bioluminescence imaging showed 7.3-fold higher luciferase expression at the tumor site and 23.0-fold less luciferase expression in liver tissue for c-H5mT/Luc relative to that for naked oncolytic Ad (n-H5mT/Luc). Considering the heterogeneity of tumor tissue, these results are important for guiding the development of more potent and specific treatment of devastating metastatic cancers using this viral system.
  
  
  CONCLUSIONS
  Although adenoviral systems have shown considerable promise and undergone extensive evaluation attempts to specifically target Ad vectors to cancer cells have met limited success. This shortcoming is due to the strong immune response stimulated by Ad and the hepatotoxicity of the viral particles. To overcome restricted vector issues, we generated Ad/mPEG-b-pHis for tumor microenvironment-targeting hybrid vector systems, an oncolytic Ad coated with a pH-responsive polymer, mPEG-b-pHis. The Ad/mPEG-b-pHis exhibited pH-dependent transduction efficiency and cancer-cell killing effects. Moreover, systemic administration of oncolytic Ad/mPEG-b-pHis led to marked suppression of tumor growth and tumor-specific viral replication. Ad successfully avoided the innate and adaptive immune responses and liver accumulation with the help of mPEG-b-pHis on its surface.
authors.affiliation: Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
authors.forename: Joung-Woo
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
authors.forename: Kasala
authors.initials: K
authors.lastname: Dayananda
authors.affiliation: Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
authors.forename: Soo-Jung
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea.
authors.forename: Soo-Hwan
authors.initials: SH
authors.lastname: Lee
authors.affiliation: School of Electrical and Electronic Engineering, Yonsei Institute of Medical Instruments Technology, Seoul 120-749, Republic of Korea.
authors.forename: Donghyun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, The University of Utah, 30 S 2000 E, Room 2972, Salt Lake City, UT 84112, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, The University of Utah, 30 S 2000 E, Room 2972, Salt Lake City, UT 84112, USA; Utah-Inha Drug Delivery Systems (DDS) and Advanced Therapeutics Research Center, 7-50 Songdo-dong, Yeonsu-gu, Incheon 406-840, Republic of Korea. Electronic address: you.bae@utah.edu.
authors.forename: You Han
authors.initials: YH
authors.lastname: Bae
authors.affiliation: Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea. Electronic address: chaeok@hanyang.ac.kr.
authors.forename: Chae-Ok
authors.initials: CO
authors.lastname: Yun
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D006801:Humans; D006863:Hydrogen-Ion Concentration; D051379:Mice; D009369:Neoplasms / Q000628:therapy*; D050130:Oncolytic Virotherapy; D059016:Tumor Microenvironment; D023041:Xenograft Model Antitumor Assays
keywords: Cancer gene therapy; Oncolytic adenovirus; Systemic administration; pH-sensitive polymers