Radiation-primed TGF-β trapping by engineered extracellular vesicles for targeted glioblastoma therapy

Abstract

The poor outcome of glioblastoma multiforme (GBM) treated with immunotherapy is attributed to the profound immunosuppressive tumor microenvironment (TME) and the lack of effective delivery across the blood-brain barrier. Radiation therapy (RT) induces an immunogenic antitumor response that is counteracted by evasive mechanisms, among which transforming growth factor-β (TGF-β) activation is the most prominent factor. We report an extracellular vesicle (EV)-based nanotherapeutic that traps TGF-β by expressing the extracellular domain of the TGF-β type II receptor and targets GBM by decorating the EV surface with RGD peptide. We show that short-burst radiation dramatically enhanced the targeting efficiency of RGD peptide-conjugated EVs to GBM, while the displayed TGF-β trap reversed radiation-stimulated TGF-β activation in the TME, offering a synergistic effect in the murine GBM model. The combined therapy significantly increased CD8⁺ cytotoxic T cells infiltration and M1/M2 macrophage ratio, resulting in the regression of tumor growth and prolongation of overall survival. These results provide an EV-based therapeutic strategy for immune remodeling of the GBM TME and eradication of therapy-resistant tumors, further supporting its clinical translation.

Keywords: Extracellular vesicles; Glioblastoma multiforme; Immunotherapy; Radiation therapy; Targeted delivery.