Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Stabilized synthetic RNA oligonucleotides (ORN) and protected messenger RNA (mRNA) were recently discovered to possess an immunostimulatory capacity through their recognition by TLR 7 and 8. We wanted to find out whether this danger signal is capable of triggering anti‐tumor immunity when injected locally into an established tumor. Using the mouse glioma tumor cell line SMA‐560 in syngenic VM/Dk mice, we were able to show that intra‐tumor injections of protamine‐stabilized mRNA do indeed induce tumor regression and long‐term anti‐tumor immunity. Residual RNA‐injected tumors show CD8 infiltration. Distant injections of protamine‐protected mRNA and intra‐tumor injection of naked mRNA also result in anti‐tumor immunity. Although they are strong danger signals, RNA are labile molecules with a short half‐life: they do not trigger side effects such as long‐term, uncontrolled immunostimulation evidenced by splenomegaly in CpG DNA‐treated mice. In conclusion, RNA molecules are potent and safe danger signals that are relevant for active immunotherapy strategies aimed at the eradication of solid tumors.</jats:p>