Injectable Supramolecular Hydrogels for In Situ Programming of Car-T Cells toward Solid Tumor Immunotherapy

Chimeric antigen receptor (CAR)-T cell immunotherapy is approved in the treatment of hematological malignancies, but remains far from satisfactory in solid tumor treatment due to inadequate intra-tumor CAR-T cell infiltration. Herein, an injectable supramolecular hydrogel system, based on self-assembly between cationic polymer mPEG-PCL-PEI (PPP) conjugated with T cell targeting anti-CD3e f(ab')2 fragment and alpha-cyclodextrin (alpha-CD), is designed to load plasmid CAR (pCAR) with a T cell specific CD2 promoter, which successfully achieves in situ fabrication and effective accumulation of CAR-T cells at the tumor site in humanized mice models. More importantly, due to this tumor microenvironment reprogramming, secretion of cellular inflammatory cytokines (interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma)) or tumor killer protein granzyme B is significantly promoted, which reverses the immunosuppressive microenvironment and significantly enhances the intra-tumor CAR-T cells and cytotoxic T cells infiltration. To the best of the current knowledge, this is a pioneer report of using injectable supramolecular hydrogel for in situ reprogramming CAR-T cells, which might be beneficial for solid tumor CAR-T immunotherapy. An injectable CAR plasmid (pCAR)-loaded supramolecular hydrogel system for long-term and sustained reprogramming of CAR-T cells in situ for solid tumor immunotherapy is introduced. After injection locally adjacent to a solid tumor, the supramolecular hydrogel platform produces in situ CAR-T cells by sustaining release of T cell-targeting nanocomplexes-carrying pCAR and significantly diminishes the immunosuppressive microenvironment or facilitates the clearance of solid tumors.image