Capitalizing on the messenger: Intra-tumoral delivery of RNA with a systemic effect.

As reported recently in Science Translational Medicine, intra-tumoral administration of mRNAs that encode four cytokines formulated in saline mediates regression of injected and distant murine tumors. The anti-tumor effect, which is also seen in the anti-PD-1-resistant setting and enhanced by checkpoint blockade, is mediated by tumor-specific T cells and natural killer cells.