Poly(lactic‐co‐glycolic acid) Nanoparticles for IL‐12 Self‐Amplifying RNA Delivery in Glioblastoma Models

ABSTRACT Glioblastoma (GBM) remains one of the most lethal brain cancers, with median survival rarely exceeding 15 months after diagnosis. Interleukin‐12 (IL‐12) is a potent immunostimulatory cytokine capable of reshaping the tumor microenvironment (TME), yet its clinical translation is hindered by systemic toxicity and short half‐life. RNA‐based local immunotherapies offer a promising alternative, with self‐amplifying RNA (saRNA) enabling sustained protein expression at low doses. However, its large size and susceptibility to degradation demand a delivery system capable of providing protection, stability, and sustained activity. Here, we report a poly(lactic‐co‐glycolic acid) (PLGA) nanoparticle platform engineered to deliver intact, large saRNA encoding IL‐12. This innovative PLGA NP platform preserved the saRNA structural integrity and drove strong IL‐12 expression in SB28 glioma monolayers and 3D spheroids for at least 72 h. In a zebrafish xenograft model, a single in situ administration of saRNA‐loaded PLGA nanoparticles induced significant macrophage recruitment to the tumor site after 92 h, demonstrating an early immunomodulatory response to the RNA therapeutic. This work establishes a robust PLGA‐based platform for the delivery of large saRNA molecules and provides a foundation for next‐generation RNA immunotherapeutic strategies against GBM.