Periodic Reporting for period 1 - grabRNA (Smart RNA delivery for therapy and diagnostic)
Reporting period: 2023-04-01 to 2024-09-30
Major bottlenecks in drug development are the identification of disease-relevant cellular targets and the subsequent development of safe and selective modulators of these targets. Since the vast majority of approved drugs addresses protein targets, it is curial to expand the space of targetable biomolecules, e.g. to Ribonucleic acids (RNA). RNA is highly under-represented drug targets and moved into the focus of drug discovery efforts, in particular, certain messenger RNAs (mRNA). RNA interference (RNAi) is an essential, post- transcriptional mechanism capable of degrading or blocking particular RNA sequences using short interfering RNA (siRNA) as starting point. Offering a specific and efficient means to suppress virtually any target gene, RNAi has become an indispensable research tool and has attracted significant interest as a therapeutic strategy. Despite considerable efforts, the widespread application of siRNA-based therapies has been limited due to a lack of effective intracellular delivery methods. Moreover, siRNA is degraded by ribonucleases which are omnipresent in cellular systems. These undesirable characteristics have fuelled efforts to develop delivery systems which disguise siRNA and facilitate its translocation and presentation to the RNAi machinery. However, so far a general solution that enables in vivo applications is lacking.
We have developed synthetic peptide-based molecules which facilitate structure-specific RNA binding and served as starting point for the design and synthesis of siRNA carriers. These carriers are composed of two RNA binding peptides that only bind their double-stranded RNA target in a homo-dimeric form. This is important as RNA cargo needs to be released once shuttled into the target cells. In our system, this is facilitated by a redox-sensitive disulfide bond between the two monomers which is cleaved upon reaching the reducing intracellular environment. We demonstrate that the stability and cellular permeability of RNA can be remarkably enhanced through complexation with the carrier molecules. The project aims to further demonstrate performance in a relevant environment thereby identifying a lead candidate. In addition, we aim to evaluate different exploitation strategies.
We have developed synthetic peptide-based molecules which facilitate structure-specific RNA binding and served as starting point for the design and synthesis of siRNA carriers. These carriers are composed of two RNA binding peptides that only bind their double-stranded RNA target in a homo-dimeric form. This is important as RNA cargo needs to be released once shuttled into the target cells. In our system, this is facilitated by a redox-sensitive disulfide bond between the two monomers which is cleaved upon reaching the reducing intracellular environment. We demonstrate that the stability and cellular permeability of RNA can be remarkably enhanced through complexation with the carrier molecules. The project aims to further demonstrate performance in a relevant environment thereby identifying a lead candidate. In addition, we aim to evaluate different exploitation strategies.
The scientific activities involved the synthesis and testing of additional peptide derivatives and the further characterization of the panel members. These tests confirmed to homo-dimeric structures, one with non-modified and one with stapled peptide sequence as best performing candidates. For those, we showed specific and high-high affinity binding of double-stranded RNA resulting in stabilization in medium. In addition, monomerization both in presence and absence of RNA under reducing conditions (as they can be found in the cytosol) was observed. Taken together these finding highlight the potential of this RNA stabilization and delivery approach. We have further refined our commercialization strategy now involves depending on the field of application, either the option to licence the technology to commercial partner and/or pursue the formation of a spin-off company.
With the project, we have extended the data set for our lead candidates enabling the search for follow-up funding and academic as well as industry partners. We have identified both out licensing and internal development via spin-off formation as potentially suitable commercialization strategies. For examples, we have already engaged in collaborations with two biotech companies to test our technology in their application fields. Importantly, not only medical RNA applications but also the use of RNA technologies for crop protection was identified as potential market.