ABSTRACT
BACKGROUND: SN-38, 7-ethyl-10-hydroxycamptothecin, is a biologically active metabolite of irinotecan. Its poor solubility restricted its development as an anticancer agent. We have developed an easy-to-use liposome-entrapped SN-38 (LE-SN38) and evaluated its toxicology, pharmacokinetics and antitumor efficacy profile. MATERIALS AND METHODS: Toxicity and pharmacokinetics studies were conducted in CD2F1 mice and beagle dogs. Therapeutic efficacy studies were performed in murine leukemia (P388 and P388/ADR) and in a human pancreatic (Capan-1) tumor models. RESULTS: Multiple dose administration (i.v. x 5) of LE-SN38 indicated a maximum tolerated dose (MTD) of 5.0 and 7.5 mg/kg/day for male and female mice, respectively. The MTD of LE-SN38 in dogs was 1.2 mg/kg. The elimination half-life (t1/2) of SN-38 in mouse plasma was 6.38 h with volume of distribution (VdSS) 2.55 L/kg. In dogs, t1/2 and VdSS were 1.38-6.42 h and 1.69-5.01 L/kg; respectively. P388 tumor-bearing mice dosed with LE-SN38 at 5.5 mg/kg (i.v. x 5) showed 100% survival. LE-SN38 at 4 or 8 mg/kg (i. v. x 5) inhibited 65% and 98% tumor growth, respectively, in a human pancreatic tumor model. CONCLUSION: LE-SN38 showed a favorable pharmacokinetics profile and can be administered safely at therapeutically effective doses.
Subject(s)
Antineoplastic Agents, Phytogenic/administration & dosage , Camptothecin/analogs & derivatives , Camptothecin/administration & dosage , Leukemia P388/drug therapy , Pancreatic Neoplasms/drug therapy , Animals , Antineoplastic Agents, Phytogenic/adverse effects , Antineoplastic Agents, Phytogenic/pharmacokinetics , Camptothecin/adverse effects , Camptothecin/pharmacokinetics , Dogs , Dose-Response Relationship, Drug , Female , Humans , Irinotecan , Leukemia P388/metabolism , Liposomes , Male , Mice , Mice, SCID , Pancreatic Neoplasms/metabolism , Xenograft Model Antitumor AssaysABSTRACT
Cationic liposomes have been successfully used as an alternative approach to viral systems to deliver nucleic acids. However, high toxicity and inconsistent transfection efficiency have been associated with the currently available liposomes. Therefore, a novel cationic liposome was developed based on a synthetic cationic cardiolipin analogue (CCLA) to test the DNA transfection efficiency. This CCLA-based liposome was also used to determine the therapeutic efficacy of c-raf small interfering RNA (siRNA) in mice. In this report, we showed that the CCLA-based liposome was less toxic and effectively transfected reporter genes in vitro and in vivo. The transfection efficiency in mice was seven-fold higher than the commercially available DOTAP-based liposome. In addition, c-raf siRNA in the presence of CCLA-based liposome induced up to 62% of growth inhibition in cancer cells. Treatment of c-raf siRNA/CCLA complex in SCID mice bearing human breast xenograft tumors resulted in 73% of tumor growth suppression as compared to free c-raf siRNA group. In conclusion, a novel CCLA-based liposome showed less toxicity and broad usage both in vitro and in vivo with DNA and siRNA.
