Study On Injectable Enzyme-responsive Hydrogel For Tumor Chemoimmunotherapy

Background: Targeting immune checkpoint pathways have shown remarkable success in various cancer types due to the immunosuppressive tumor microenvironment,low tumor immunogenicity and high cost,the application of immune checkpoint inhibitors is limited,not all patients benefit from this treatment approach.T cell immunoglobulin and immune receptor tyrosine-based inhibitory motif domain(TIGIT)has recently entered the limelight as a promising immune checkpoint due to its prominent innate and adaptive immune responses.Injectable hydrogels have attracted considerable attention as vehicles for localized and sustained drug delivery,due to a minimally invasive administration procedure,good syringeability and biocompatible.Aim: Intratumorally implanted hydrogel would go through a gradual enzymaticdegradation process to sustainably liberate doxorubicin(DOX)and a TIGIT.After being stimulated by released DOX,the immunogenic tumor would recruit the infiltration of NK cells and effector T cells which could be further aroused by the subsequently released a TIGIT to boost multilayered innate and adaptive immune responses.Methods: First of all,the injectable enzyme-responsive GAB hydrogel was prepared by cross-linking the ε-amino groups of lysine or hydroxylysine side groups of gelatin and available aldehyde groups of Alginate dialdehyde(ADA)molecules through Schiff’s base formation.The rheological dynamics test confirmed that GAB hydrogel has good injectable and self-healing properties.It is proved that GAB hydrogel has good biocompatibility at cell level and animal level respectively.The released DOX and a TIGIT was detected by its own fluorescence or the Rat Ig G Total ELISA Kit,respectively.To study the antitumor effect of enzyme-degrading GAB hydrogel combined with chemotherapy and immunotherapy in breast cancer-bearing mouse models,and to explore its mechanism of action.Results: We have engineered an enzyme-responsive hydrogel that can respond to the abundant matrix metalloproteinase 2/9(MMP2/9)within the tumor microenvironment(TME)for controlled sequential release of doxorubicin(DOX)and a TIGIT.The combination drugs increase the numbers of T cells and natural killer(NK)cells and reduces the frequency of immunosuppressive cells in tumors,which contributes to improving the efficacy of tumor immunotherapy.Therapeutic advantage of this DOXa TIGIT-GAB hydrogel based localized chemoimmunotherapy was further demonstrated in not only inducing systemic immunity to inhibit metastatic tumor but also promoting the development of long-lasting immune memory effect in the relatively lowimmunogenic 4T1 breast tumor mouse model.Conclusion: Our findings revealed that this combination therapy inhibits the local tumor growth,metastasis and recurrence in 4T1 breast cancer-bearing mice.