title: Optimization of (1,2-diamino-cyclohexane)platinum(II)-loaded polymeric micelles directed to improved tumor targeting and enhanced antitumor activity.
abstract: Polymeric micelles are promising nanocarriers, which might enhance the efficacy of antitumor drugs. Herein, polymeric micelles incorporating dichloro(1,2-diamino-cyclohexane)platinum(II) (DACHPt), the oxaliplatin parent complex, were prepared through the polymer-metal complex formation of DACHPt with poly(ethylene glycol)-b-poly(glutamic acid) [PEG-b-P(Glu)] block copolymer having different lengths of the poly(glutamic acid) block [p(Glu): 20, 40, and 70 U]. The resulting micelles were studied with the aim of optimizing the system's biological performance. DACHPt-loaded micelles (DACHPt/m) were approximately 40 nm in diameter and had a narrow size distribution. In vivo biodistribution and antitumor activity experiments (CDF1 mice bearing the murine colon adenocarcinoma C-26 inoculated subcutaneously) showed 20-fold greater accumulation of DACHPt/m at the tumor site than free oxaliplatin to achieve substantially higher antitumor efficacy. Moreover, the micelles prepared from PEG-b-P(Glu) with 20 U of P(Glu) exhibited the lowest non-specific accumulation in the liver and spleen to critically reduce non-specific accumulation, resulting in higher specificity to solid tumors. The antitumor effect of DACHPt/m was also evaluated on multiple metastases generated from intraperitoneally injected bioluminescent HeLa (HeLa-Luc) cells. The in vivo bioluminescent data indicated that DACHPt/m decreased the signal 10-to 50-fold compared to the control indicating a very strong antitumor activity. These results suggest that DACHPt/m could be an outstanding drug delivery system for oxaliplatin in the treatment of solid tumors.
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Horacio
authors.initials: H
authors.lastname: Cabral
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D004337:Drug Carriers / Q000008:administration & dosage*; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D008823:Micelles; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D009944:Organoplatinum Compounds / Q000008:administration & dosage*; D010984:Platinum / Q000008:administration & dosage; D011108:Polymers / Q000008:administration & dosage; D023041:Xenograft Model Antitumor Assays / Q000379:methods
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D008823:Micelles; D009944:Organoplatinum Compounds; D011108:Polymers; D010984:Platinum