Objective:This study aimed to develop a new polyethylene glycol (PEG)ylated β-elemene liposome (PEG-Lipo-β-E) and evaluate its characterization,pharmacokinetics,antitumor effects and safety in vitro and in vivo.Methods:The liposomes were prepared by ethanol injection and high-pressure micro-jet homogenization.Characterization of the liposomes was conducted,and drug content,entrapment efficiency (EE),in vitro release and stability were studied by ultra-fast liquid chromatography (UFLC) and a liquid surface method.Blood was drawn from rats to establish the pharmacokinetic parameters.The anticancer effect was evaluated in a KU-19-19 bladder cancer xenograft model.Histological analyses were performed to evaluate safety.Results:The PEG-Lipo-β-E showed good stability and was characterized as 83.31 ± 0.181 nm in size,0.279 ± 0.004 in polydispersity index (PDI),-21.4 ± 1.06 mV in zeta potential,6.65 ± 0.02 in pH,5.024 ± 0.107 mg/mL in β-elemene (β-E) content,and 95.53 ±1.712％ in average EE.The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated the formation of PEG-Lipo-β-E.Compared to elemene injection,PEG-Lipo-β-E demonstrated a 1.75-fold decrease in clearance,a 1.62-fold increase in half-life,and a 1.76-fold increase in area under the concentration-time curves (AUCs) from 0 hour to 1.5 hours (P ＜ 0.05).PEG-Lipo-β-E also showed an enhanced anticancer effect in vivo.Histological analyses showed that there was no evidence of toxicity to the heart,kidney,liver,lung or spleen.Conclusions:The present study demonstrates PEG-Lipo-β-E as a new formulation with ease of preparation,high EE,good stability,improved bioavailability and antitumor effects.