Study On Dasatinib Liposomes With Anti-tumor Effect In Prostate Cancer

Dasatinib is a tyrosine protein kinase inhibitor clinically used in the therapy of accelerated,myeloid or lymphoid chronic myelogenous leukemia(CML)in adults resistant or intolerant to former treatments.Dasatinib is also under investigation for the treatment of solid tumors,including prostate cancer,lung cancer and pancreatic cancer.Because SRC and LYN,the two target enzymes of Dasatinib highly expressed in prostate cancer,therefore Dasatinib showed promising effect in prostate cancer in phase II clinical research.However,the therapeutic efficiency of dasatinib is liminted to its poor water solubility and severe gastrointestinal adverse effects resulted from high dosing regimen.In this thesis,we therefore selected liposome as the delivery vehicle for Dasatinib to improve its bioavailablity via intravenous injection,and studied the preliminary anti-tumor effect of the liposomal Dasatinib in PC-3 prostate cancer in nude mice model.Based on the p H-dependant solubility of Dasatinib,we screened several buffers and selected acetate buffer at p H 3.6 as the solvent of Dasatinib.The solulibity of Dasatinib in the acetate buffer is increased to10mg/m L.We also studied the precipitates of Dasatinib with different counter ions and selected two ions,sulfate and methylsulfonate for the remote loading of Dasatinib.Blank liposomes composed of HSPC/cholesterol/DSPE-PEG2k(3:1:1,w/w)in the mean size of 90 nm were prepared by ethanol injection method.Dasatinib was remote loaded into the blank liposomes using ammonium sulfate and ammonium methanesulfonate as the intraliposomal gradient,respectively.Both formulations achieved encapsulation efficiency higher than 95% with drug concentration of 3.2mg/m L.The two Dasatinib lipsomes showed very similar slow release behavior in saline.The cumulant release was less than 5% at 48 hr.While,in the 40%albumin-saline solution(w/v),the liposomes using ammoniumn sulfate as the internal aqueous phase showed much slower release.There was only20% Dasatinib released from the ammonium sulfate liposomes at 48 hr in the albumin solution.We hyphothezied that the different physical state(arrangement)of the Dasatinib salt with sulfate or methysulfonate inside lipsomes may attribute to the difference in vitro release behavior.The inhibition effect in PC-3 cells proved that the Dasatinib liposomes inhibited the cell proliferation at concentrations lower than10 n M.The inhibition effect did not increase as Dasatinib concentrations were higher than 1μM.Lipo-Dasatinib showed long circulation profile and sustained drug release in the healthy SD rats after intravenous injection with significantly increased bioavailability than that of the Dasatinib solution.The results of tissue distribution showed that Dasatinib could be detected in the heart,liver,spleen and kidney after intravenous injection of Lipo-Dasatinib.The two Lipo-Dasatinib also showed a significant anti-tumor effect in prostate cancer nude mice compared with the control.In conclusion,Dasatinib liposomes prepared in this thesis achieved high encapsulation efficiency,high drug loading and sustained in vivo release of Dasatinib.They significantly increased the the bioavailability of Dasatinib and showed good inhibition effect on tumor growth in prostate cancer nude mice.The study provides a delivery vehicle of Dasatinib with high bioavailability in solid tumors therapy.It may also serve as an example for the formulation design,prepearation and controlled-release of liposomes for poorly water-soluble drugs.