Immune therapies based on direct injection of GMP- quality stabilised messenger RNA

F. von der Mülbe1, S. Soltwedel1, J.-P. Carralot1,3, B. Scheel1, R. Teuffel1, B. Weide2, K. Garbe2, T. Ketterer1, G. Jung1, H.-G. Rammensee3, I. Hörr1 and Steve Pascolo1

1-CureVac the RNA people GmbH, Tübingen, Germany, 2-Hautklinik, Tübingen, Germany, 3-Institut for Cell Biology, Tübingen, Germany

e-mail: sp@curevac.de

We showed that direct injection in mice of ß-globin stabilised messenger RNA (ßg-mRNA) either naked or associated to the cationic peptide protamine triggers an immune response against the antigen encoded by the ßg-mRNA (Hörr et al, EJI, 2000). Towards the characterisation and improvement of the ßg-mRNA-based vaccination we found that the injection of naked or protamine-protected RNA triggers a Th2 type of response. When GM-CSF is used as an adjuvant, it can shift the ßg-mRNA-induced immune response towards a Th1 type of response. Besides, studying the intrinsic adjuvant capacities of RNA, we discovered that protected RNA (protamine-associated or containing a phosphorothioate backbone) is a very powerful danger signal that can activate through Toll Like Receptor several cell types including mouse and human dendritic cells. We also show that such a new danger signal is efficient as an anti-tumour treatment when injected directly intra-tumour in mice. In order to transfer these ßg-mRNA-based vaccination and anti-tumor treatments from pre-clinical to clinical applications (in human) we established the method and the facilities necessary to produce mRNA under GMP (Good Manufacturing Practice) conditions. The whole process starts from fermentation and goes through in vitro transcription before chromatography purification (according to the mRNA size) and packaging. We will present our pre-clinical data in mice, the GMP production process and the preliminary results of the ongoing clinical trials where direct injection of ßg-mRNA are used for anti-tumour therapies.