Combination Of Combretastatin A4 Nanodrugs With BLZ945 Nanoparticles For Tumor Therapy

Cancer is a serious threat to human health.Chemotherapy is one of the most common treatments to cancer.However,many small-molecule chemotherapy drugs have problems,such as poor water solubility,low targeting,and high toxicity and side effects,which hinders their further clinical application.Nanodrugs can improve these shortcomings including enhancing water solubility,facilitating tumor targeting and reducing toxicity and side effects.Vascular disrupting agents(VDAs)are one of the potential anti-tumor therapeutics which can restrain tumor growth through destroying tumors blood vessels and blocking oxygen and nutrient supply for tumors.Combretastatin A4 nanoparticles(CA4-NPs)are polymeric VDAs which notably inhibit tumor growth with stronger tumor vessel targeting and low side effects.CA4-NPs are anti-tumor nanodrugs with great potential.However,CA4-NPs were found to cause tumor regrowth due to the intratumoral enrichment of immunosuppressive M2-type macrophages which led to immunosuppressive microenvironment of tumors.Since BLZ945,an inhibitor of CSF-1 receptor(CSF-1R),depletes and inhibits the proliferation of M2-type macrophages whose survival and proliferation rely on CSF-1R,it has the potential to relieve immunosuppressive microenvironment and improve anti-tumor therapy of CA4-NPs.However,CSF-1R exists widely,and BLZ945 could cause potential hepatotoxicity.It is necessary to establish a tumor-targeting drug delivery system to enhance the target of BLZ945 to tumors and reduce the off-target and side effect of BLZ945.In this study,coagulation-targeting BLZ945-loaded nanoparticles(A15-BLZ-NPs)were developed,and combined with CA4-NPs for anti-tumor therapy,aiming to tumor-targeted deliver BLZ945,specifically regulate tumor immunity,improve anti-tumor effects and reverse immunosuppressive microenvironment.The main research contents and conclusions of this dissertation are summarized as follows:(1)Firstly,we developed coagulation-targeting BLZ945-loaded nanoparticles(A15-BLZ-NPs).To improve the loading capacity of PEG5k-PLA5k to BLZ945,we synthesized BLZ945-poly(D,L-lactide)(BLZ945-PLA)through ring-opening polymerization of D,L-lactide.Then A15-BLZ-NPs were prepared by encapsulating BLZ945-PLA into poly(ethylene glycol)-poly(D,L-lactide)(PEG5k-PLA5k),and decorating A15,a substrate of activated blood coagulation factor XIII(FXIIIa),on the surface PEG segment.A15-BLZ-NPs could crosslink to fibrin through elevated FXIIIa and target specifically intratumoral coagulation spots induced by CA4-NPs.It was confirmed that A15-BLZ-NPs had suitable diameters and good stability in vitro,and BLZ945 was continuously released from A15-BLZ-NPs in different condition(pH 7.4 and pH 6.8).In vitro cytotoxicity indicated that the survival and proliferation of macrophages could be suppressed by A15-BLZ-NPs.(2)Then we combined A15-BLZ-NPs with CA4-NPs for anti-tumor therapy.CA4-NPs induced the enhanced distribution of BLZ945 in tumors,as the BLZ945 concentration was 3.75-fold in CA4-NPs+A15-BLZ-NPs group than that of A15-BLZ-NPs single treatment.The anti-tumor evaluation indicated that the combined treatment effectively improved the tumor inhibition rate to 73.4%,significantly,which was higher than that of CA4-NPs(15.5%)or A15-BLZ-NPs(23.9%)single treatment.Finally,the changes of immune cells in tumors were analyzed at 48 h post-injection.Compared to CA4-NPs group,the combined treatment significantly reduced the proportion of immunosuppressive M2-type macrophages and enriched immune activated M1-type macrophages and cytotoxic T lymphocytes,suggesting the A15-BLZ-NPs remodeled and activated tumor immunity after CA4-NPs treatment,which controlled tumor progression and improved anti-tumor therapy.Through the investigation of this dissertation,the results were expected to provide the basic experimental evidence and a new strategy for developing nanodrugs to specifically regulate tumor microenvironment,and also provide the theoretical and experimental basis for further research and application of polymeric vascular disrupting agents.