title: Encapsulation, controlled release, and antitumor efficacy of cisplatin delivered in liposomes composed of sterol-modified phospholipids.
abstract: We employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shorter acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well-studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.
authors.affiliation: Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA; Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California, San Francisco, CA 94143-0912, USA.
authors.forename: Heidi M
authors.initials: HM
authors.lastname: Kieler-Ferguson
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California, San Francisco, CA 94143-0912, USA.
authors.forename: Darren
authors.initials: D
authors.lastname: Chan
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California, San Francisco, CA 94143-0912, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sockolosky
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Lydia
authors.initials: L
authors.lastname: Finney
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Maxey
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vogt
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, School of Pharmacy, University of California, San Francisco, CA 94143-0912, USA. Electronic address: szoka@cgl.ucsf.edu.
authors.forename: Francis C
authors.initials: FC
authors.lastname: Szoka
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D002784:Cholesterol / Q000737:chemistry*; D002945:Cisplatin / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000188:drug therapy; D003692:Delayed-Action Preparations; D005260:Female; D006207:Half-Life; D006801:Humans; D008081:Liposomes; D020714:Maximum Tolerated Dose; D008807:Mice, Inbred BALB C; D010743:Phospholipids / Q000737:chemistry*; D014018:Tissue Distribution
chemical_list: D000970:Antineoplastic Agents; D003692:Delayed-Action Preparations; D008081:Liposomes; D010743:Phospholipids; D002784:Cholesterol; D002945:Cisplatin
keywords: C26 colon carcinoma; Cisplatin; Liposome; Sterol-modified phospholipid; X-ray fluorescence microscopy