title: In vivo antitumor activity of cis-bis-neodecanoato-trans-R,R-1, 2-diaminocyclohexane platinum(II) formulated in long-circulating liposomes.
abstract: A lipophilic cisplatin derivative, cis-bis-neodecanoato-trans- R,R-1,2-diaminocyclohexane platinum (II) (NDDP), was formulated in liposomes composed of phosphatidylcholine (PC) and cholesterol (Chol) additionally containing monosialoganglioside (Gm1) or polyethyleneglycol conjugated to phosphatidylethanolamine (PEG-PE). These NDDP-containing long-circulating liposomes were examined for in vivo antitumor activity using the mouse RIF-1 solid tumor as a target residing outside the reticuloendothelial system (RES). Biodistribution studies, using C3H/HeJ mice and 111In-labelled DTPA-SA as a lipid marker, showed that the activity of GM1 and PEG-PE in prolonging the circulation times of liposomes was preserved in the presence of 3.0 mol% of NDDP in the liposome membranes. The high levels of liposomes remaining in the blood for PC/Chol/GM1 and PC/Chol/PEG3000-PE liposomes were associated with high levels of platinum in the blood as determined by atomic absorption spectrophotometry. These NDDP-containing long-circulating liposomes showed approximately a three-fold increase in tumor accumulation as compared to the conventional PC/Chol liposomes. In vitro cytotoxicity studies using RIF-1 tumor cells showed that the presence of PEG-PE, but not Gm1, significantly enhanced the cytotoxicity of liposomal NDDP. RIF-1 tumor-bearing C3H/HeJ mice were treated twice with 25 mg/kp NDDP in various liposomal formulations on days 12 and 16 after tumor cell inoculation. A significant reduction in the tumor growth rate was observed when NDDP was formulated in PC/Chol/PEG3000-PE liposomes which support both efficient tumor accumulation and enhanced cytotoxicity of liposomal NDDP. On the other hand, NDDP formulated in PC/Chol/GM1 liposomes, which display only a high tumor accumulation, had no effect on the tumor growth rate. Furthermore, NDDP formulated in dimyristoylphosphatidylglycerol (DMPG)-containing liposomes, exhibiting in vitro cytotoxicity comparable to NDDP formulated in PC/Chol/PEG3000-PE liposomes, but showing poor tumor accumulation, was also not effective. These results indicate a potential effectiveness of NDDP formulated in PEG-PE-containing liposomes for therapy of tumors in non-RES organs.
authors.affiliation: Department of Pharmacology, University of Pittsburgh School of Medicine, Pennsylvania 15261, USA.
authors.forename: A
authors.initials: A
authors.lastname: Mori
authors.forename: S P
authors.initials: SP
authors.lastname: Wu
authors.forename: I
authors.initials: I
authors.lastname: Han
authors.forename: A R
authors.initials: AR
authors.lastname: Khokhar
authors.forename: R
authors.initials: R
authors.lastname: Perez-Soler
authors.forename: L
authors.initials: L
authors.lastname: Huang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D002470:Cell Survival / Q000187:drug effects; D002784:Cholesterol; D004337:Drug Carriers; D005260:Female; D005354:Fibrosarcoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005677:G(M1) Ganglioside; D008081:Liposomes; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D009944:Organoplatinum Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010984:Platinum / Q000032:analysis; D011092:Polyethylene Glycols; D012995:Solubility; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D008081:Liposomes; D009944:Organoplatinum Compounds; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C054367:bis-neodecanoato-1,2-diaminocyclohexaneplatinum(II); C067972:dioleoyl-N-(monomethoxypolyethylene glycol succinyl)phosphatidylethanolamine; D005677:G(M1) Ganglioside; D011092:Polyethylene Glycols; D010984:Platinum; D002784:Cholesterol