Orchestrated metal-coordinated carrier-free celastrol hydrogel intensifies T cell activation and regulates response to immune checkpoint blockade for synergistic chemo-immunotherapy

The challenges generated by insufficient T cell activation and infiltration have constrained the application of immunotherapy. Making matters worse, the complex tumor microenvironment (TME), resistance to apoptosis collectively poses obstacles for cancer treatment. The carrier-free small molecular self-assembly strategy is a current research hotspot to overcome these challenges. This strategy can transform multiple functional agents into sustain-released hydrogel without the addition of any excipients. Herein, a coordination and hydrogen bond mediated tricomponent hydrogel (Cel hydrogel) composed of glycyrrhizic acid (GA), copper ions (Cu2+) and celastrol (Cel) was initially constructed. The hydrogel can regulate TME by chemo-dynamic therapy (CDT), which increases reactive oxygen species (ROS) in conjunction with GA and Cel, synergistically expediting cellular apoptosis. What's more, copper induced cuproptosis also contributes to the anti-tumor effect. In terms of regulating immunity, ROS generated by Cel hydrogel can polarize tumor-associated macrophages (TAMs) into M1-TAMs, Cel can induce T cell proliferation as well as activate DC mediated antigen presentation, which subsequently induce T cell proliferation, elevate T cell infiltration and enhance the specific killing of tumor cells, along with the upregulation of PD-L1 expression. Upon co-administration with aPD-L1, this synergy mitigated both primary and metastasis tumors, showing promising clinical translational value.