Immunotherapeutic Hydrogel with Photothermal Induced Immunogenic Cell Death and STING Activation for Post-Surgical Treatment

Post-surgical tumor recurrence remains a major clinical concern for patients with malignant solid tumors. Herein, an immunotherapeutic hydrogel (SA PBA /ZMC/ICG) is developed by incorporating metal ion-cyclic dinucleotide (CDN) nanoparticles (Zn-Mn-CDN, ZMC) and a photosensitizer (indocyanine green, ICG) into phenylboronic acid (PBA)-conjugated sodium alginate (SA PBA ) for photothermal therapy (PTT)-triggered in situ vaccination to inhibit post-surgical recurrence and metastasis of malignant tumors. The gelation of SA PBA /ZMC/ICG in the residual tumors can achieve accurate local PTT and the local sustained release of CDN and Mn 2+ with minimal detrimental off-target toxic effects. Furthermore, CDN, which is an agonist of the stimulator of interferon genes (STING), along with Mn 2+ can activate the STING pathway and trigger type-I-IFN-driven immune responses against tumors. Therefore, the immunotherapeutic hydrogel with enhanced immune response by STING agonist and PTT-induced immunogenic cell death (ICD) reprograms the post-surgical immunosuppressive microenvironment, substantially decreasing the post-surgical recurrence and metastasis of solid tumors in multiple murine tumor models when administered during surgical resection. Taken together, PTT-triggered and STING-mediated in situ cancer vaccination is an effective therapeutic intervention for post-surgical recurrence and metastasis of tumors.