TransNAT: Transforming delivery, safety and efficacy of nucleic acid therapeutics: from intracellular uptake to targeting brain and muscle.

Nucleic acid therapies (NATs) are genetic medicines that address the root cause of disease and have the potential to transform healthcare and provide life changing solutions for numerous areas of unmet need. Neurological, neuromuscular and cardiovascular diseases in particular devastate lives and create a very significant economic and social burden across the entire global population. While NATs have begun to be a reality over the last decade with multiple medicines being approved for use in the US and Europe many challenges remain particularly for diseases outside the liver and for those not easily addressed by local drug delivery solutions. Moreover, recent clinical trial results indicate that safety considerations should be addressed in parallel with the development of delivery solutions. The challenge of NAT delivery put simply is to deliver the drug effectively across the cell membrane into the appropriate sub-cellular compartment at a sufficient concentration required for activity in the absence of significant safety signals - so called 'productive' delivery. Our proposed solution is therefore to understand the requirements for productive delivery of NATs and to exploit this knowledge base for the development of NAT conjugates - our technical solution. Building on extensive experience of our consortium of academic and industry scientists, we will take two independent approaches to NAT conjugates, where delivery agents are directly chemically attached to the NAT drug. First, we will study and optimise lipid conjugates, where a range of lipid entities are directly attached to the NAT via a series of chemical linkers with different properties. In the first instance the NAT is one targeting a common gene of no therapeutic relevance. Our second approach of high potential will be to study and optimise antibody conjugates, where an antibody (or antibody fragment or antibody derived peptide) that binds to a specific cell membrane ligand is conjugated chemically again via chemical linkers. In each case, we will have starting points with conjugates that have already emerged through the work of consortium members, and in the case of antibodies we will have two independent approaches for identifying and prioritising new ligands for antibody targeting, again building on pre-existing work in the consortium. Our extensive chemistry capabilities will generate conjugate materials and control compounds for study and first step of which will be extensive in vitro studies in cells to develop mechanism-based knowledge on productive cell uptake allowing us to select lead compounds for more detailed study based on cell uptake/efficacy/safety properties, and to iterate compound structure and chemistry based on new knowledge, know-how and data generated. Further study will comprise translational studies in ex vivo human model systems based on human cells and stem cells and also based on human three dimensional organ like systems that provide cell diversity and architectural arrangements more closely mimicking human tissues. Further translational studies in established and new rodent models will allow delivery to cells and tissues of brain, heart and muscle to be studied in detail at singe cell resolution permitting cell/tissue biodistribution to be correlated with efficacy and safety measures. Finally, a small number of lead NAT compounds will be studied in disease models related to Huntington's disease and muscular dystrophy. We will maximise the potential of data by analysing and integrating across the programme and implementing machine-learning approaches to exploit our data. We will deliver fundamental knowledge, know-how, data and IP on productive uptake and novel lipid/antibody NATs of high therapeutic potential for further study. We will also engage the broader NAT community via reports/meetings/conferences and develop training opportunities, all of the above working in close collaboration with the NATA Hub.

CNS and neuromuscular diseases devastate lives and create vast global economic costs (>$817Bn in 2021). Nucleic acid therapeutics (NAT) have huge potential to treat such disorders by addressing the disease cause. Despite recent advances, significant challenges in NAT delivery to many cell/tissue types remain. Recent clinical trials have identified toxicity issues, emphasising the need to consider safety in parallel with efforts to improve delivery. Our aim is to achieve productive, safe NAT delivery, leading to the intended activity, and this can only be accomplished by advancing mechanism-based understanding and developing NAT bioconjugates that address the technical demands. Here we establish a world-leading consortium to address the NAT delivery challenge, advancing the study of improved NAT compounds to understand the mechanistic basis of productive NAT uptake and its implications for intracellular/in vivo delivery, trafficking, safety, and delivery to CNS, heart, and muscle. We will develop and study a range of next-generation NAT compounds (focussing on lipid and antibody/peptide bioconjugates) to be evaluated as follows:
1 Mechanistic in vitro studies of cell uptake, endosomal escape, compartment (cytoplasm/nucleus/mitochondria) localisation - quantifying productive cell uptake, distribution, safety and efficacy readouts.
2 Development of novel ex vivo human tissue organoid models to screen and evaluate cell/tissue delivery, safety, and efficacy.
3 Translational in vivo studies in wild-type and novel reporter rodent species to investigate CNS and heart/muscle delivery, using available consortium tool compounds against reporter/other targets e.g. MALAT1 and quantifying distribution and efficacy at single cell resolution.
4 Selection of lead NAT compounds to study in clinically relevant disease models e.g. HD and DMD.
5 All data will be analysed and integrated computationally to allow machine-learning-based advances in NAT development to be made.