Rationally Engineered Coronavirus-mimicking Protein Nanocage Platform for Glioblastoma Targeted Delivery and Immunity Regulation

Glioblastoma (GBM) is one of the most aggressive and treatment-resistant brain tumors, owing to the dual challenges of the blood-brain barrier (BBB) and a profoundly immunosuppressive tumor microenvironment. However, few existing strategies are capable of simultaneously overcoming these two barriers, underscoring a critical scientific gap and the need for innovative therapeutic platforms that enable both effective BBB traversal and tumor immune reprogramming. Here, we present a coronavirus-mimicking protein nanocage platform (EcomPC) derived from Thermotoga maritima encapsulin, rationally engineered for the targeted and sustained delivery of interferon- (IFN-) to GBM lesions. Through strategic insertion of flexible linkers, cysteine-to-serine mutations, and modular surface functionalization via SpyTag/SpyCatcher chemistry, EcomPC enables intracellular self-assembly of IFN- and glioma-specific targeting. In orthotopic GBM models, EcomPC-IFN demonstrates efficient BBB translocation, selective tumor accumulation, and potent anti-tumor efficacy. Mechanistically, localized IFN- release induces tumor cell apoptosis and reprograms the immune microenvironment--characterized by increased CD8 T cell infiltration, decreased Foxp3 regulatory T cells, and a favorable chemokine shift. These therapeutic effects are not recapitulated by free IFN- or untargeted nanocages, underscoring the essential role of both structural mimicry and ligand-guided delivery. Collectively, this work establishes EcomPC as a programmable, virus-inspired protein delivery platform capable of overcoming key physiological barriers in brain tumor immunotherapy, and lays the foundation for its broader application in CNS-targeted biologic delivery.