Systemic Administration Of Oncolytic Adenovirus Complexes Coated With Lipids And Calcium Phosphate For Hepatic Carcinoma Therapy

Objective Oncolytic adenovirus(OncoAd)is a promising therapeutic agent for treating cancer.The advantages of using OncoAd in cancer gene therapy include not only cancer cell-specific replication and the destruction of infected cells,but also the high expression of inserted therapeutic genes,leading to potent antitumor efficacy.Several human clinical trials have reported the successful usage of OncoAd in local cancer gene therapy.Systemic administration is importance to treat cancer metastases.However,the efficacy of intravenously administering OncoAd is compromised by non-specific sequestration in the liver,pre-existing anti-adenovirus immunity and the innate immune response.To overcome these problems and achieve efficient antitumor effects,more efforts are needed to re-design the OncoAd.In this study,we developed an oncolytic adenovirus delivery system for ZD55-IL-24,an oncolytic adenovirus that carries the IL-24 gene,and applied it for hepatic carcinoma therapy.Study strategy Design of oncolytic adenovirus systemic delivery system: Ca P and ZD55-IL-24 were coprecipitated at first.Then,an amphiphilic phospholipid,Dioleoylphosphatydic acid(DOPA)which is known to strongly interact with cations,formed lipid bilayer spheres around Ca P / ZD55-IL-24.The outer m PEG2000 could form a hydrophilic protective layer around the DOPA/Ca P/ZD55-IL-24 complexes,which could facilitate longer circulation times after intravenous administration.Function evaluation and antitumor efficacy validation of the systemic delivery system: Firstly,the systemic delivery system was characterized and optimized.The function evaluation include stability,long circulation,liver toxicity and immune escape.The bio-distribution and tumor target delivery efficiency were examined to confirm the antitumor efficiency and the safety in vivo.Methods and Results In this study,we developed an oncolytic adenovirus delivery system coated with lipids and calcium phosphate for ZD55-IL-24(PLC-ZD55-IL-24).The mean size of PLC-ZD55-IL-24 was 121 nm.PLC-ZD55-IL-24 were dispersed with with a zeta potential of-10.1 m V.Function evaluation was performed in vitro and in vivo.After a 10 day-storage at 4?,the average size of PLC-ZD55-IL-24 did not change,and the cytotoxicity of PLC-ZD55-IL-24 was scarcely decreased.Serum stability assay showed that PLC-ZD55-IL-24 resisted the serum-induced aggregation,which could result in prolonged circulation time.In BALB/c mice,systemic administration of PLC-ZD55-IL-24 did not increase the serum level of IL-6,ALT,AST,and no obvious pathological signs of hepatotoxicity was observed.PLC-ZD55-IL-24 efficiently evaded the pre-existing immunity in vivo and achieved tumor target delivery in pre-existing immunity mice bearing Hepa1-6 tumors.PLC-ZD55-IL-24 inhibited hepatocellular carcinoma cell proliferation by induction of apoptosis,harbouring the same antitumor mechanism with ZD55-IL-24.After systemic administrated the PLC-ZD55-IL-24 in mice bearing Huh-7 tumors,Real-time quantitative PCR(q PCR)was used to detect the copy number of adenovirus.The results demonstrated that the systemic administration of the ZD55-IL-24 could reduce sequestration,prolong the circulation time and achieve efficient tumor-target delivery in vivo.In addition,a fluorescence imaging system was utilized to monitor GFP intensity in tissues to confirm the targeting delivery capacity.An increased injection dose of PLC-ZD55-GFP could enhance the fluorescence intensity,with the tumor-to-liver ratio did not significantly change.Mice bearing Huh-7 tumors were systemic administrated PLC-ZD55-IL-24.The expression level of IL-24 in tumors was significantly increased compared to that of naked ZD55-IL-24-treated tumors.The percentage of tumor growth inhibition in high dose PLC-ZD55-IL-24-treated group and low dose PLC-ZD55-IL-24-treated group were 54.62% and 37.40%,respectively.The results suggested that an increased therapeutic dose of PLC-ZD55-IL-24 enhanced antitumor efficiency in vivo.At the end of treatment,both serum biochemistry assay and tissue section HE staining showed no significant organ functional lesion.Conclusion In this study,we successfully constructed an oncolytic adenovirus(OncoAd)systemic delivery system(PLC-ZD55-IL-24).Masking the surface of OncoAd shielded it from sequestration in liver,prolonged circulation time,and protected it from neutralization by pre-existing neutralizing antibodies.After systemic administration,PLC-ZD55-IL-24 induced negligible hepatic toxicity and a negligible innate immune response.The efficient tumor-targeting ability and anti-tumor effect were observed.Increasing the dose of PLC-ZD55-IL-24 dramaticlly improved the therapeutic efficacy and prognosis without inducing severe toxicity.These results indicated that PLC-OncoAd might be a safe and effective platform to improve the delivery efficiency of OncoAd via systemic administration for cancer gene therapy.