Injectable adhesive hydrogel-drug complexes synchronize the release of chemoimmunotherapy to treat brain tumors in mice

Brain tumor therapy remains limited by an immunosuppressive, monotherapy-resistant tumor microenvironment and by a paucity of technologies capable of controlling therapy delivery kinetics to the tumor. Here, we describe tissue-adhesive hydrogel-drug complexes (HDCs) for the controlled release of combination therapies synchronized with immune cycle responses following intracranial administration. Injected adhesive HDCs enabled the controlled co-delivery of multiple payloads (chemotherapy, stimulator of interferon genes agonist cyclic dinucleotide nanoparticles, immune checkpoint blockade antibodies), leading to enhanced long-term survival (>80%) and protection from contralateral hemisphere rechallenge after a single dose in multiple syngeneic orthotopic glioblastoma mouse models. Mechanistic studies revealed that tumor rejection is a consequence of reprogramming the tumor microenvironment, driven by three key phases: the initial rapid expression of inflammatory cytokines, notably IFN-{gamma}, and tumor sensitization with antigen exposure during chemoimmunotherapy release, followed by the recruitment and subsequent sustained activation of antigen-presenting and effector cells facilitated by the hydrogels multiweek delivery period. These findings point to tissue-adhesive HDCs, and therapeutic release synchronized with biological responses as key considerations for realizing robust immune activation without provoking toxicity in the treatment of solid tumors.