Synergistic Chemoimmunotherapy Augmentation via Sequential Nanocomposite Hydrogel-Mediated Reprogramming of Cancer-Associated Fibroblasts in Osteosarcoma.

In osteosarcoma, immunotherapy often faces hurdles posed by cancer-associated fibroblasts (CAFs) that secrete dense extracellular matrix components and cytokines. Directly removing CAFs may prove ineffective and even promote tumor metastasis. To address this challenge, we developed a sequential nanocomposite hydrogel that reshaped CAF behavior, enhancing tumor-infiltrating T cells in osteosarcoma. Our approach utilized an injectable blend of carboxymethyl chitosan and tetrabasic polyethylene glycol, forming a nano hydrogel for controlled release of a potent CAF suppressor (Nox4 inhibitor, Nox4i) and liposomal Doxorubicin (L-Dox) to induce immunogenic cell death (ICD) upon in situ administration. Nox4i effectively counters CAF activation, overcoming T-cell exclusion mechanisms, followed by programmed L-Dox release for ICD in stroma-rich osteosarcoma models. Combining the co-delivery gel with αPD-1 checkpoint inhibitor further enhanced its effectiveness in an orthotopic osteosarcoma model. Immunophenotyping data underscored a significant boost in tumor T cell infiltration and favorable anti-tumor immunity at the whole-animal level. This article is protected by copyright. All rights reserved.