Development of stealth liposome formulation of 2'-deoxyinosine as 5-fluorouracil modulator: in vitro and in vivo study

• Published in: Pharmaceutical research 2005-12, Vol.22 (12), p.2051-2057
• Main Authors: Fanciullino, Raphaelle, Giacometti, Sarah, Aubert, Claude, Fina, Frederic, Martin, Pierre-Marie, Piccerelle, Philippe, Ciccolini, Joseph
• Format: Article
• Language: English
• Subjects: Animals; Antimetabolites, Antineoplastic - pharmacology; Apoptosis - drug effects; Cell Line, Tumor; Cell Proliferation - drug effects; Chemistry, Pharmaceutical; Chromatography, High Pressure Liquid; Cytotoxicity; Drug Delivery Systems; Drug Synergism; Enzyme Inhibitors - pharmacology; Fluorouracil - pharmacology; Inosine - administration & dosage; Inosine - analogs & derivatives; Inosine - pharmacology; Lasers; Lipids; Liposomes; Male; Mice; Mice, Nude; Neoplasm Transplantation; Oncology; Pharmacokinetics; Polyethylene glycol; Rats; Rats, Wistar; Scattering, Radiation; Thymidylate Synthase - antagonists & inhibitors
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1007/s11095-005-8355-9

The aims of this study were to develop a stealth, pegylated liposomal formulation of 2'-deoxyinosine (d-Ino), a 5-fluorouracil (5-FU) modulator, to evaluate its efficacy in vitro and in tumor-bearing mice, and to study its pharmacokinetics in rats. After designing a pegylated liposome encapsulating d-Ino (L-d-Ino), we evaluated its efficacy as 5-FU modulator in vitro. Antiproliferative assays, thymidylate synthase (TS) inhibition, and apoptosis studies were carried out to check whether an optimization of 5-FU action was achieved on the 5-FU-resistant SW620 cell line. Animal pharmacokinetic and ex vivo studies were next performed to confirm that L-d-Ino displayed a slower plasma elimination pattern than free d-Ino. Finally, effects on tumor growth of L-d-Ino + 5-FU combination was evaluated in xenografted mice. We developed a stable, sterile, and homogenous 100-nm population of pegylated liposomes encapsulating 30% of d-Ino. Liposomal d-Ino exhibited a strong potential as 5-FU modulator in vitro by enhancing TS inhibition and subsequent apoptosis induction, while displaying a better pharmacokinetic profile in animals, with a near seven times clearance reduction as compared with the free form. When used in tumor-bearing mice in combination with 5-FU, our results showed next that the association led to 70% of tumor reduction with a doubling median survival time as compared with untreated animals, whereas 5-FU alone was ineffective. Our data show that liposomal d-Ino, through an optimized pharmacokinetic profile, displays a potent effect as fluoropyrimidines modulator, both in vitro and in xenografted mice. Besides, we showed here that it is possible to reverse a resistant phenotype to 5-FU, a major drug extensively described in clinical oncology.